1956 Buick Differential Rebuild

[Janousek]

I spent 8 years changing 3-5 ring and pinions a day in a test lab.   The spider gears rarely give any trouble and I'd leave them alone.   A noisy rear end will always be noisy.  No way to quite gears that have lapped together and make noise.  I've switched out a couple used pigs into a 53' Buick and they were all noisy.  This was after I replaced the carrier and pinion bearings setting them to stock specs and running a pattern on them.

 

I don't feel that a lot of shops really understand setting up a differential.  It can be a pain and very time consuming if the pattern isn't right.  300 bucks wouldn't be enough to really dial one in if was way out.  If you have to pull the bearings a few times for setup then it takes a while.  We used to have slip on pinion and side bearings to speed the setup up.  Once the pattern was good then you replaced the slip on bearings with press on ones.   But... Most of the times taking a rear end and just putting bearings in doesn't effect the pattern.  Swapping ring gears on different carriers is where the tolerances usually go out.   

 

I'm surprised their isn't a solid effort for a bunch of new gears to be ran.   Seems like a lot of guys could benefit from a 3.42 gear ratio.   If I ever get around to finish my 48' special I'll probably have a set cut.  Unfortunately that runs around 3k for one set, but I don't want to mess around with a bunch of crap which seems to be all that is left in differential land.  

 

I run a high quality mineral based 140 wt in the cars I setup but I don't drive in the cold.  It is thinner than a lot of the junk that pours out of the originals. 

[JohnD1956]

Noisy rear axles are no problem when you hit my age.  CHP ( can't hear crap) can be an asset.  But just for entertainment here is a true story from my personal experiences:

In the summer of 1973, I had the chance to ride with my future In-laws in the back seat of their 70 Chevelle convertible.  It was one of the few times I actually rode in the back seat, and I was amazed at the howl coming from the rear axle area.  I asked about it and must have set my father in law thinking about the possibility of a breakdown.  This car was well under 100K at the time and as luck would have it an Uncle happened to have a wrecked 70 Skylark, which they thought would be a bolt in swap.

One day I was surprised to find out that the Uncle and F-I-L spent the last two days swapping the rear ends over, just to find out the Skylark rear end also howled!  Turned out to be the low cost recapped tires my F-I-L was running!  Once they put a set of new tires on the howl disappeared.

[Guest]

On 12/28/2016 at 5:32 PM, Beemon said:

Thanks for the offer! I'll definitely PM you about that rear end if the one I habe doesn't work out for me. Do you know what the gears are by chance? I know highway gears are always preferred but the differential also absorbs a lot of moment forces and if you go too light, you run risk of mechanical failure. 

Just to be fair, not every rear cover I've removed presents rusty gears. Mostly looking for that holy grail of 3.6 from the 38's with early automatic. Prized by folks with those cars and not much else fits. Just shopped at a yard I thought was doomed! Another yard bought it from the family of the owner who passed.Took off Dual left ex. Manifold '56, goin back for the '57. Spark plug covers, front fender stainless54-56. 5-600 cars, not all Buicks but a lot. Woohoo. Is this heaven? No you fool it's midwinter in "southern" Minni-snow-dah! Gets up to like 15 or 20. Balmy with no wind. Best of all no snakes chiggers or mosquitos, I'm also usually the only one there. Imagine that!

[Beemon]

While yes, the main goal of swapping gears is to get rid of the noise, the other issue is that the case hardening on my original gears have been worn off. This means the metal is extremely brittle and can blow at any time. Anything is an upgrade, sound or not, though I hope it's not noisy.

 

I've also looked into having my own guts cut for a pretty penny, but for the same price you can do a driveline swap and gain other added benefits of upgrading, such as a more efficient transmission and a rear end that's new and not "lightly used."

 

John, I think I'm still a few years away from that milestone.

Edited January 10, 2017 by Beemon (see edit history)

[Janousek]

Quote

 

I've also looked into having my own guts cut for a pretty penny, but for the same price you can do a driveline swap and gain other added benefits of upgrading, such as a more efficient transmission and a rear end that's new and not "lightly used."

 

 

That is why the ford 9" from Curry and all those other aftermarket vendors are so popular.   Wouldn't be as easy with the Torque tube Buick but any other car it makes sense.  For a lot less money you can have a premium drivetrain.   I hate to say it but a 700r4 and a 9" would be a heck of an upgrade for a cost of getting a set of gears cut.  I'd never do it in my 48' because it's a stick and I want it original.  

 

 In another club a guy had 10 sets cut and the price dropped down to 2,200 a set.  

[Beemon]

I'm reviving this thread because I'm hoping to tackle this over the weekend if the weather permits. We're back in the 50s again and I want to have the rear end in before the 26th of March, where the car will make its first pilgrimage over Snoqualmie pass on the 5 hour trip to Pullman, WA (Basically driving from Seattle to the Idaho border).

 

This is what I have to work with. The driveway is actually pretty level for never been grated since the house has been in the family ('91). The lowest point on the car aft the axel is the exhaust at 9 inches off the ground. The frame is approximately 6 inches so I'm going to only need to lift it 4 inches to pull the rear out with the tires off. A buddy is coming over to pull it out while I lay on a yoga mat to catch the driveline on my stomach before it hits anything. I feel like this is some really ugly backyard mechanic stuff so please feel free to chime in before you look me up in an obituary lol. 

 

Also I would like to hear some oil preferences. I know we discussed weights before, but should I go synthetic or conventional? Synthetics range between 75W-90 to 70W-140 and conventional fluids are usually 80W-90 and 80W-140. Found some interesting articles about Amsoil with affidavits to confirm a truthful, undoctored test, but it sounds too good to be true. I've also been told Royal Purple and Redline diff fluids, but in the Amsoil tests they're usually dead last.

Edited February 16, 2017 by Beemon (see edit history)

[old-tank]

Think and plan way ahead with jack stands on heavy plywood.

I usually roll the assembly out on some empty rims.  And use a small floor jack under the front of the torque tube as a roller.

[Janousek]

Here is some probably outdated info that was from the mid to late 90's.  GM switched the trucks axle lube from mineral to synthetic.  Probably 80-90 weight but I'm not positive anymore.  This was a fuel milage change.   The gear testing that I ran back then would show the backsides of the pinions and thrust washers with more gauling than with mineral lube.  It didn't affect the life of gear testing it just show more abrasive wear like it didn't protect as much under load.   It didn't matter for our testing it was just something I noticed but my "production part approval process" parts passed the durability tests with either oil.  

 

I'm sure this could be and has been addressed with additives to the synthetic oil.  

 

Another huge problem we had was with limited slip packs squeeking during that testing.  We had to use their synthetic gear lube during the clutch pack testing.  The machines would start chirping after the wear pattern was established.  I didn't run those particular machines unless someone went on vacation or such.  They were trying different additives to the base syn. lube to stop this chirping.  We found that regular mineral lube would stop this chirping instantly.  But... that wasn't an option and they had to develop additives that wouldn't chirp.  The customer complaint would amount to an SUV turning into a parking spot the limited slip would chirp around the corner.  

 

For these reasons I use a premium mineral based 140 weight in our diffs and transmission and haven't had any trouble.  We run the cars in Michigan from april to November so their is some 40 degrees operation.  I see no need to run a thinner oil and the 140 keeps some of the drips away.  

[NTX5467]

GM is still using syn rear axle lube in most everything.  There's got to be a reason other than fuel economy, I suspect, as I know of one rear axle that fried ([pulling a trailer) when somebody put normal lube in the pickup truck rear axle.  Type of oil shouldn't cause that issue, but it sounded strange, anyway.  I believe there are a few different syn rear axle lubes, depending upon application . . . another mystery!

 

The ltd slip units are "unlocked until they lock", as a governor weight has to swing out to engage the clutches (with different wheel speeds happening), unlike the old PTrac units with springs (either 4 separate springs or one S-shaped spring) that were "locked until they unlocked/slipped to go around tighter corners.  It was usually a lh turn that would cause issues as the clutches tried to slip but usually didn't.  That's what the old PTrac additive was supposed to fix.  GM had a special pn lube for the PTracs, but went to "normal lube + PTrac additive by the later 1960s-early 1970s.  Then a "universal rear axle lube" later on.

 

ONE issue with using syn fluids where they never were spec'd is SEAL COMPATIBILITY as some syn fluids can degrade the rubber seals over time.  THAT can cause longevity issues, big time.  One reason why Dex VI is a semi-syn atf that is backward compatible to the first HydraMatic produced (as prior Dex fluids were).  I'd recommend finding a good, quality OEM-type dino rear axle fluid of whatever weight you might desire and use that.

 

Personally, I'd start with the lighter viscosity variation of 90"weight" rather than the heavier ones.  Main reason is power consumption with the heavier viscosities.  The lighter fluid can also help wash into all areas of the rear axle guts.  Then if it all works well and quietly, change the oil and see how it goes.  I have read Old-Tank's recommendation of the heavier viscosities, which I completely respect as he normally does "what works for him", but I'm thinking about how much precious power and fuel that heavier oil must be requiring.   More "drag" with that heavier rear axle fluid might make the DynaFlow think it's always running slightly uphill?  Just my theory.

 

Hoping you have a successful venture!

 

NTX5467

Edited February 19, 2017 by NTX5467 (see edit history)

[Beemon]

Just wanted to chime in: we got it out, swapped diff carriers and got the rear back under the car. At about 8 PM it started raining Friday and we called it quits. As it sits, the coils are mounted but the axle still needs to mate to the Dynaflow. Before, I ran Royal Purple 75W-90 and it didn't leak at all except at the backing plate, but that was because when they did the rear end, they used the old gaskets. I just found out about it yesterday, too, and I've been driving the car probably 7 months like that now. Not a huge leak as the diff case was still full to the plug, but it ruined the shoes so now I'm into a full rear brake overhaul. There wasn't any fluid in the torque tube and the front seal looked good so I didn't replace it. It probably took us a good half hour to figure out that if you flip the rear axle upside down, there's a good flat spot to pound the torque tube off the carrier... lol. This time I opted for Mobil 1 75W-90 Synthetic and I'll see how that goes. While a lot of people don't regard the Amsoil test papers as proof of quality oils, there are several affidavits supplied that show if they were to be challenged and found guilty of forgery, they could be sued. I was surprised to see that the RP wasn't that great of an oil, but upon closer inspection, Amsoil didn't rig their numbers to put their competetor in last place, they just used arbitrary tests that have nothing to do with differential wear to get them lower scores. Interesting enough, the Mobil 1 oil Synthetic was just as good as the Amsoil product to a degree, with the Castrol LSD conventional being the best dino oil. They didn't have the Castrol oil on the shelf so I went with the Mobil 1 synthetic.

 

Also I suckered in a colleague to help. He said "hey that sounds pretty cool I think I would enjoy working on old cars." Couldn't have been more wrong.

 

Today was rainy. Tomorrow I plan on mating the two up, then re-attaching all the small stuff. I bought some 5" 3/8 bolts and I cut the heads off them because it was cheaper than buying 2 feet of round stock. I'm going to use them as pegs and screw them in to the Dynaflow so I can properly guide the driveline in. I'm really excited to drive down the road and the only sound the car makes is vroom noises.

[NTX5467]

Thanks for that update and additional information!  The exuberance of youth!!  And propensity to do new things!!  And devising new strategies to confront old situations to make things work better!!

 

Glad that things have worked well for y'all AND I hope it continues!

 

Please keep us posted.

 

NTX5467

 

[Janousek]

12 hours ago, NTX5467 said:

 

 

Quote

 

The ltd slip units are "unlocked until they lock", as a governor weight has to swing out to engage the clutches (with different wheel speeds happening), unlike the old PTrac units with springs (either 4 separate springs or one S-shaped spring) that were "locked until they unlocked/slipped to go around tighter corners.  It was usually a lh turn that would cause issues as the clutches tried to slip but usually didn't.  That's what the old PTrac additive was supposed to fix.  GM had a special pn lube for the PTracs, but went to "normal lube + PTrac additive by the later 1960s-early 1970s.  Then a "universal rear axle lube" later on.

 

 

These limited slips were the old school limited slips with clutch paks and spring paks.  The force of the gear teeth act as ramps and put pressure against the clutch discs to keep power on both wheels.  They acted like a regular diff around the corner unless you stomped it to get the gear teeth ramping up against the clutch discs.  They ran them for a short period in the Trailblazer/Sabb/Bravada platform on certain packages.  The GM limited slip additive wouldn't fix the chirping.   Mineral oil would right away.   They were playing around with different stability systems and the G80 locker wasn't that compatible back then.  I have now idea now but I know the pickups still offer the g80.  That is the one with the flyweights that lock the rear end up completely under 30 mph.   Nice unit for a pickup and I bet I could still build one blindfolded.  

 

Early on the switch to synthetic caused the front pigs to weap at the axle seals.  One of the fixes was to lower the lube height under the fill hole by 10mm.  That helped.  The synthetic seems to weap in the old cars even more than regular lube.    Most the seals are single lip or felt and not as effective as the seals designed for it.   

 

We were told fuel milage was the reason for the synthetic lube.  Could very well be other reasons but everything about every part was cost.  They wouldn't have done it if they didn't have to.  I wish I could go back and spend some time on the tester that would tear up ring and pinions.  We weren't testing those but several would fail before our parts would.  The mineral was going away when I was there early on.  Shortly after it went all synthetic.  Synthetic probably took higher heat but our temperatures were controlled with heat exchangers.  I can still smell that stink when the synthetic went up in smoke.  

 

Our 31' Buick with 140 in the trans and differential gets 14 mpg running 55-60 mph for hours on end.  I can't complain about that and wouldn't run something thinner to try for better.  Maybe getting into the 50's the thinner oils might be better designed?  Tolerances are still the same though.  .006 ring and pinion backlash has been a rough rule of thumb throught the decades.  

 

Enough babbling, I'm glad to see you progressed this far on the project.  That torque tube is a pia for the Buick mechanic.  Great ride though.  

[NTX5467]

Thanks for that information!  Down here in moderate-temp (usually) TX, PTracs are an "order" item rather than "necessary" for many.  I can certainly understand how an "open" differential would work better with the then-coming (now standard) StabiliTrac systems.  I found a video on the current "flyweight" limited slip in GM pickups.  The wheel speed differential amount makes the flyweight engage the clutches, that that OTHER set of flyweights disengages it at about 45mph (another mystery solved!).  Most of the TrailBlazer vehicles were sold were not Ptrac vehicles.

 

GM has had a sales training video of how THEIR "locker" is better than what others offer.  One of the first ones was of a pickup towing a normal ski boat up an incline, with one wheel on a traction-compromised surface and the other one on a good surface.  The Chevy made it to the top as the others lost momentum and stopped mid-track.  The other one is a pickup going across a concrete drainage ditch (sloped sides rather than vertical).  The others get to where only one wheel can move the vehicle, which is where they need a tow, but as the Chevy eases to that point, one wheel spins about one revolution, the whole truck shakes as the "locker" engages, and then it continues onward through the ditch.  The same G80 option code, but apparently different differential guts.  In the above comparisons, each pickup had their manufacturer's "limited slip" rear axle option.  This was when Chevy started calling theirs "lockers", on the 1/2 tons.

 

In prior times, a "locker" manually engaged "dogs" to lock the two axle shafts together with no slip between them.  Think "Power Lok" from the later 1960s muscle cars and 3/4 ton pickups.  The "limited" in "limited slip" allegedly means "limited slip between the two axle shafts" rather than, as we always perceived, "limiting slippage of rear wheels as both wheels would drive the vehicle when one wheel had compromised traction.  Some of the European magazines claimed about a 75% "locking" rate for clutch-type "limited slip" axles.

 

The torque bias of the limited slip axle also means that the left rear wheel rises rather than the right one, under hard acceleration situations.  I found that out on our ;69 CST-10 when I'd punch it in a parking lot and more wheelspin was evident from the left side.  Open rear axles only spun on the rh rr wheel by comparison.  The above percentage also explained why the two tire tracks left by our pickup were not equal, but heavier on the lh than rh.

 

Personally, I tend to have more confidence in the old spring-loaded PTrac rather than electronic systems for added traction.  At least the old PTracs won't put additional wear in rear brake friction elements when such systems are "on" and rear wheelspin happens.  My orientation might change as I get older, though.

 

The synthetic fluids probably help with the EPA "treadmill" emissions (and related fuel economy) testing.  They flow immediately as a part of their nature so that's less drag on the engine, which equates to fewer emissions from the tail pipe in those tests.  This is just ONE of many strategies to minimize emissions during that test.  The benefits of each one might be very minimal, but all together, can make some things good enough to be an advertising "crowing" point.  In our older carbureted vehicles, more of a slight dulling affect upon throttle response might be more noticeable than any savings in fuel usage, I suspect.

 

Whatever works best . . . .

 

NTX5467

Edited February 19, 2017 by NTX5467 (see edit history)

[Janousek]

Thanks for dragging up old memories NTX.  We used to help with those promotional videos at the proving grounds.  Dog and Pony shows is what we called them.   The locker always outperformed the limited slip since 100% torque was transferred.  The limited slips will lock the rear wheels in a straight line on pavement but usually would smoke the clutch packs in the events the videos show.   In the winter states the g80 was a better bet because a posi can cause the rear end to come around on ice.  Normal dry roads it's fine but ice can screw with a posi if the rear traction can't overcome the bias torque required to get the pinions spinning.  

 

The g80 will not unlock unless your turn your steering wheel lightly one way or the other to move the spider gears to unlock it.  The flyweight can't disengage unless the pressure is taken off of it.  It's not a problem as a slight turn of the wheel does the job.   It's a good performer that has been around since the 70's in GM trucks.  It was really the only viable candidate for a locker from the 70's - 2000's.  It had good manners where some of the other ratchet ones were noisy.   Most of the aftermarket designs were more rugged offroad but weren't acceptable on the street.  

 

They were playing with electronic lockers and such back then.  Basically pins would be controlled with a magnet (basically an A/C clutch magnet).  They worked good off-road and all the Hummer lines either came standard or an option.  (can't remember which).  

 

They had some neat hydraulic controlled ones that worked well with the stability systems.  Grand Cherokees used those.  A pump was used in the differential and controlled by an electronic soleniod.  Sounded good on paper but my complaint was contaminents from the ring and pinion.   The differential always makes a lot of wear in crap as the magnets on the cover always show.  This junk would cause problems on the pump.   I always thought it was a good paper idea but not in a real world 100k mile application.  External pump might have gotten me on board.

 

Back then the stability stuff was supposedly going to take over and obsolete the g80 and other systems.  I don't think we moved as fast what everybody thought 12+ years ago.  That is fine with me as their is to much crap on new cars.   

 

I don't mean to hijack the post,  you just sent me down memory lane in between block sanding parts today.  Not sure If I'm the smart one to replace gear lube with restoring old cars but that is what I did back in 05'.   

[Beemon]

Good read guys. I figured if at some point this rear end doesn't work out and I'm forced to go a slightly different route, it would definitely be a LSD open drive mod with a more modern transmission. I suppose it's just the way things go. Parts get more and more scarce to the point where classic cars turn into Cuban cars.

 

Anyways, I'm having some difficulty aligning the driveshaft the the tailshaft of the Dynaflow. I have a 4" bolt going through the driveshaft into the tailshaft flange and I have one dowel pin on the opposite side. Should have thought about leveling the car out on stands before starting... I've got a jack under the diff, a jack under the driveshaft, and since the drive shaft wants to gravitate towards the driver side of the car, I'm thinking maybe a ratcheting strap on the passenger side. My time ran out and the rains came so I'm getting wet tomorrow. At some point the tailshaft on the Dynaflow got stuck in an upwards position, so I had to loosen the torque ball retainer until there was a slight drip to get it to flex. Maybe not enough shims? It moved freely afterwards, like it was just dry and needed some wetting. The diff is free floating suspended only by the jack and the coil springs and the wheels are off the ground. I'm so close, I feel if I can get the third pin or bolt to line up on the driveshaft/tailshaft bolt holes, I'll have enough triangulation to get it in there.

[JohnD1956]

Bring the rear axle up by temporary attachment of the rear shock absorbers.  That should make the axle on the same plane that the vehicle is on.  Just slide the lower bolts to the shocks in place, and leave the attaching nuts off till the torque tube is seated at the trans.

[Beemon]

Following John's advice, it indeed leveled the rear end enough for me to put two ratchet straps on the tip of the driveline behind the x frame to align the drive shaft side to side. I then used another jack to set elevation. The old man came up today to be my wheel expert and he turned the drove wheel for me to set the spline. Was quite a shock when the driveline went thunk and fell right in to place. The torque tube flange is still 1 inch away from the torque ball flange but at least it's in. We double checked: put the car in park, I held the driver side wheel and he couldn't turn the passenger side,  put the car in neutral and he could turn it. 

 

Thursday is supposed to be clear of rain so I'll pick up there, but I'm glad the hard part is over. Not sure why it won't budge on the last inch. I know it's in because the spline is about an inch and a half and we did the wheel test. 

[JohnD1956]

If the axle is still hanging at the max travel position I would suggest raising it a few more notches on the jack.  Trying to get it to the regular ride height before bringing it together with the bolts at the torque ball flange.

 

Just a question though,  I presume you made sure the driveshaft and torque tube was the same length as your original right?  Just in case your replacement axle ame from a big bodied Buick, which is about an inch longer.

[Beemon]

The drive shaft and torque tube are unchanged, I just swapped the carrier only. I'll try that next John. I was thinking it night have to do with the car sitting. 

[JohnD1956]

One more thing, make sure your jack under the rear axle can roll easily.  If need be, put the tires back on and let the assembly roll on them while tightening

[Beemon]

Just wanted to let you guys know after during the forum hiatus, I got everything put back together.

 

 

 

John, you must have done this before... lol. Put two 3 feet long 2x2s under the tires and with one ratchet pull, it slid all the way flush. For the entire ordeal, I used one small bottle jack, two 56 Buick floor jacks and a 4 ton floor jack. One of the axle seals also blew on the driver's side, so before I got into bleeding, I replaced the rear set of shoes. It's been cold up here. Crawled out from underneath the car the last night after tightening everything up, only to find all the windows covered in ice. I guess it was 28 degrees outside, but I didn't feel a thing. I got my girlfriend a blanket and used her foot (please no jokes lol) for brake bleeding. The final verdict? The car is dead quiet, except the engine of course. On initial takeoff, there is a small whine that disappears after 15 MPH. I'm not sure if it's the torque converter in the Dynaflow spooling up or if it is the rear end. Over the next couple days, I'll  watch the oil level since the differential front seal was suspect. If the wine is the diff, then I would think the oil is maybe too thin and is making a little bit of noise until properly lubed? If so, I'll just put some of that sticky Lucas additive in there... I took the car down the interstate to check the driveline, and there was a vibration at about 65MPH, so per the shop manual, I tested the car in Low at about 40MPH and there wasn't any vibration at all. I'm thinking it's maybe my front drums since one of them was oblonged. That's for another topic.

 

Thanks everyone for all your help. The car feels very refreshed and I'm just ecstatic I can have conversations in the car without talking over the diff, or driving in fear that one day it'll blow. Speedometer is still off, but closer to the real values so much that 65 is 60. and 70 is 65. I'm thinking of trying to put a reducer in there, when I was under the car, there seemed to be more room than I thought.

 

[old-tank]

9 hours ago, Beemon said:

Speedometer is still off, but closer to the real values so much that 65 is 60. and 70 is 65.

Check both the speedometer and odometer with a GPS.  If the odometer is reading more miles than actual, leave it alone since your gas mileage will seem better than it is  .  No, really if both are off, then it can be corrected with a driven gear with one more tooth than what is there now; or with larger diameter tires.  Report back with the number on yours...I may have a replacement.

Good work under much less than ideal conditions!

You will probably learn to ignore those small noises, since you are listening for any little thing.  When I rebuilt my first 55 rear, I noticed a whine on float (maintaining steady speed on level ground) at around 55 mph...I found that all my 55's had that whine that I never noticed!

[NTX5467]

Beemon, ONE of these days, you'll get "a shelter" and one of the requisite "rocket ship" space heaters and THEN you can really enjoy what you're doing in the off season!

 

I knew you were focused on what you were doing, but that was proven when you discovered the ice on the car!  I hope that didn't make you feel cold all of a sudden!

 

I'm very glad that you've gotten one more significant improvement to your Buick completed.  As mentioned, when things "get quiet", you hear lots of other things you hadn't heard before.  Many "normal" sounds that are a part of the uniqueness of cars from one brand to another, or model year to model year.  Embrace and enjoy them for what they might be and where they come from!

 

Thanks for the information on your project.  What's next?

 

Take care,

NTX5467

[Beemon]

2 hours ago, old-tank said:

Check both the speedometer and odometer with a GPS.  If the odometer is reading more miles than actual, leave it alone since your gas mileage will seem better than it is  .  No, really if both are off, then it can be corrected with a driven gear with one more tooth than what is there now; or with larger diameter tires.  Report back with the number on yours...I may have a replacement.

Thanks, Willie! I definitely hear everything else now, that's for sure. When replacing the driving gear, you have to take the torque ball retainer off, correct?

 

3 minutes ago, NTX5467 said:

Thanks for the information on your project.  What's next?

 

Thanks for the kind words Willis. I think mechanically the car is rock solid. I still need new coil springs on the rear but the air shocks are taking the slop for now. In terms of necessity, I would like to swap timing covers with a 57-62 to get away from the dual action pump and find a way to either convert a Newport wiper to bowden cable or find a way to adapt that 55 Chevy wiper motor I rebuilt. And replace the timing chain. I also want to do a top down inspection on the lifter valley because I can't seem to shake one noisy lifter and I want to see how wear in is going. Would also like some late model aluminum rocker arms, adjustable pushrods and stiffer valve springs for additional lift, but I think this is getting into the wishlist. Paint is definitely next, followed by clock and radio. I won't have the money to do door panels and carpets/seats/headliner this year, so I'll probably end up pulling the panels off and scrub them down good with some citrus cleaner or Dawn. It worked out well on my driver panel, until I touched it with filthy hands again... I'm also using a Bosch Sun tach remake, which is nice, but would eventually like the real thing up to 5k RPM with the old tach box mounted to the fender.

 

There's a gentlemen in Shelton, WA which is an hour away from me that does radio conversions using the Aurora solid state chips and that's probably where I'll take it, to avoid shipping damages. He also does quartz conversions to the clock, but I'm hoping the clock is just gunked up from years of retirement and just needs a good point file. I've decided to also thin my tax return by doing most all the body work on my Buick myself. There isn't a whole lot to do, just sand and maybe fill pits around the sweep spear. MAACO said they would fiberglass holes in the car for the time being, all I need to do is cover the car in etching primer. Here's hoping I don't break the windshield or rear window!

[old-tank]

14 minutes ago, Beemon said:

When replacing the driving gear, you have to take the torque ball retainer off, correct?

replace the driven gear...

(on the side of the transmission where the cable is attached)  Count the teeth or read the number.

[Beemon]

Willie, as the rains would let me, I finally got under the car and I have a 19 tooth driven gear. If the speedo is reading more than the GPS, then I should maybe find an 18 tooth gear? I'm going to my favorite yard in the morning since they're specifically open on Saturdays without an appointment to pull one off of a 56 Special. With the radio out, I haven't driven the car since the rear axle swap and the rains have been relentless.

 

I used this calculator. I don't know how accurate it is, but when I put in the 8 tooth driving gear, 3.23 rear end with 225/75R15 tires, it comes up with a driven gear of 18.4.

[old-tank]

7 hours ago, Beemon said:

I have a 19 tooth driven gear. If the speedo is reading more than the GPS, then I should maybe find an 18 tooth gear?

You would need a 20 tooth driven gear.

[Daves1940Buick56S]

If you can't get the gear you need, or if it still isn't right with the proper one, may I suggest getting a ratio translator. They go at the trans end of the speedo cable. You specify the ratio, up or down, and they will get as close as they can. I needed 1.23 increase, was able to get 1.235. Cost is about $90. Several vendors do this, I used Commercial Speedometer in Sacramento. Had it in 2 days. Go out and do a mileage check on your odometer on a marked interstate to get it exact. Don't use the speed readout, just the odometer.

 

Cheers, Dave

 

[NTX5467]

Interesting "calculator" link!  I did something of that nature for friends who had changed tires and rear axle ratios on their cars.  First was to take the OEM production combination and find the number of cable revs/mile for THAT combination.  Then use that formula to plug in other values to see what the new combination would need to maintain the established revs/mile for the cable.  Same with tire size (revs/mile from a spec sheet for tire sizes and such).  To me, it was more accurate and scientific than the old "add a tooth" sort of thing, which put the speed more correct without worrying about the odometer reading.  Before the modern plastic gears, there were metal driven gears.  No "color", but other identifying stamps/marks.  To do all of that, you needed to know where to find the specs you needed.  The linked calculator does it for you.

 

NTX5467

[JohnD1956]

There is a lot of great stuff on the web.  Thanks for pointing it out Ben. 

[Beemon]

So I went for a little jaunt this morning and it seems to be that the odometer is the same as the GPS, but the speedometer is fast. I find this kind of silly because shouldn't speedometer guys calibrate the speedometer to the odometer? Or is this normal for an off speedometer? I'm under the impression, the odometer is also driven by the speedometer cable. In any case, I won't be able to play with speedo parts since I never made it out to the junkyard. Today was my grandmother's birthday, so the family took my grandfather and the car out to see her. Luckily I know the guy who runs the yard on a personal level (friend of a family friend) so I can really go out any time, just at his convenience. There's a few 55s, and one 56 Special - all with the floors rusted out - so I'm hoping I can pull an 18 off the 56 Special and a 20 off the 55.

[Daves1940Buick56S]

It should be, but recall the odometer is geared directly to the cable, and the speedometer is driven by a spinning magnet (also driven by the cable) that induces motion in a speed cup whose action is opposed by a hairspring. Plus 2 pivots which can get dirty and likewise oppose the motion. And the magnets can lose magnetism, I just had to deal with this, I had my speedo in pieces. So lots to get out of whack there. If you can get it to within 5 mph that's good. It's the odometer you want spot on.

[Beemon]

Odometer seems to be spot on, then, but will have to do a long drive on a flat stretch of highway because the GPS doesn't account for elevation. If it is the speedometer only, then maybe I should invest in a dash swap at some point.

[old-tank]

54 minutes ago, Beemon said:

Odometer seems to be spot on

fix the speedometer.

[NTX5467]

Elevation?  I wondered about that, too, but with GPS, as observed Garmin speed on uphill stretches always matched that of the vehicle speedometer, I figured the distance would too.  Elevation can matter (in speed calibrations) as the vehicle speed varies due to terrain, but I suspect distance is minimally-affected.

 

When I did speedometer calibration checks, I'd always work to maintain a constant speed for the duration of the check.  Kind of like a speed/distance rally vehicle needing to maintain a particular speed for "the race".  This CAN be an acquired art!  Texas roads might not be as flat as many perceive, with lots of little ups and downs, so keeping an eye on the speedometer is necessary PLUS being "in tune" to the feel and sounds of the vehicle involved!  It's easier to use a 10 mile stretch of road (makes the numbers work easier), but 5 miles can work, too, for the odometer checks.  Having a digital wristwatch set on "timer" works well, too.  Speed checks should be done a mile at a time, but using two  or more miles can lead to errors, by observation.  You generally have a better focus on speed issues when it's a mile at a time.

 

Have your target speed well-stabilized as you approach the first mile marker, then start the timer.  As you pass the next mile marker, note the time.  60 seconds = 60 mph.  Then set-up for the approaching next mile marker.  Repeat.  If the numbers are pretty close, you're done, IF you did it right and accurately.  Then continue for the completion of the odometer check.  60mph = 88 ft/second.  For higher speeds, you'll need to get the "feet/second" speed to see how many "seconds/mile".     

 

There should be a "speedometer" app for your smartphone, too.  Using the internal gaming accelerometer(s) to determine speed and related distance.  It might be a part of another app that has an "at the wheels" horsepower "dyno" function.

 

NTX5467

[Guest]

Look at this on eBay http://www.ebay.com/itm/292049801822 Hey Beeman!  brand new ring and pinion in Billings MT 159.00

[Beemon]

Wow! Hopefully it's not gone by the time my tax returns hit.

[1956322]

Not to potentially steal this out from anyone but would this work in a 56 special??

[Beemon]

That rear end is only in the 56 Special. You're welcome to it, mine doesn't make any noise after I swapped rear ends.

Edited March 13, 2017 by Beemon (see edit history)

[1956322]

Darn so these gears wouldn't work?