Matt Harwood

1941 Buick Limited Limousine

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Thanks for all the awesome discussion on shocks. There are a lot of factors to consider and I think simple trial-and-error will be the best path to seeing what might be "wrong" with the suspension.

 

Also, isn't the big thing about "gas charged" shocks not to change the damping rate but rather to reduce the foaming of the oil and keep the shock performance more consistent over a wider spectrum of conditions? I seem to recall that's what the commercials in the '70s were telling me.

 

Anyway, I think it's important to point out that the Limited rides rather well and most people wouldn't complain. The only reason I noticed is because I drove that all-original 1942 Packard sedan I bought a few weeks ago, and it was notably more supple over the big, sharp bumps. My 1941 Cadillac 60S was also better at going over those sharp bumps than the Buick. 


The Packard is on ancient Lester bias-plys. My Cadillac 60S was on radials. The radials on the Limited are Hercules truck radials, and maybe they're a bit more heavy-duty than a regular tire, but surely if they were too stiff, truck owners would complain, too, no? I'm going to try to find their specifications and see how they compare to the radials I used on the Cadillac.

 

When I first bought the Buick it was on Firestone bias-plys and it CRASHED over bumps. I mean, I thought the glass was going to pop out of the windshield it hit bumps so hard. The steering column would shake side-to-side in my hands. ka-BOOOM! I changed to radials after driving the car to Allentown for the BCA National Meet a few years ago and ride quality improved in every way, although there was still a sharp impact going over larger bumps. Was going over a large, sharp bump better or worse? Hard to say, but it wasn't different enough for me to note a change. I usually run the tires at about 32 PSI, but the manual suggests 25 PSI, so I could air them down even more. That would surely improve ride quality but at the expense of tire life, but would it improve it dramatically? Additionally, these tires are rated to 60 PSI, so running them at less than half their designed pressure may not be good for them. That's a long way to say I'm not 100% convinced that the tires are 100% of the problem. When I get the car back from the exhaust shop, I'll air them down to 25 PSI as recommended and see how they feel.

 

Two years ago, I had the shocks rebuilt by Apple Hydraulics and the impact harshness improved dramatically. The secondary crashes that were shaking the steering wheel were diminished but not gone. As I said, I really only noticed it most recently when I had another car to which I could compare it. 

 

There's an expansion strip in the road where it transitions between pavement and a bridge, and I have to cross it to get home every day. I cringed in anticipation of that bump when I first bought the car, I cringed after I changed to radials, and I still cringe today. Bias-ply tires, good shocks or bad shocks, regardless of air pressure in the tires, the suspension struggles to manage that kind of bump. My Cadillac CTS wagon feels it, Melanie's Focus ST really feels it, but that Packard largely ignored it. A clue?

 

When my rear suspension was bottoming out, I called Lazar at Apple Hydraulics and he told me that all the shocks they rebuild get ISO 32 hydraulic oil. He recommended a change to the ISO 100 I'm using now and it made a VERY positive difference in the behavior of the rear end. No more floating and the bottoming-out was greatly diminished. I have not verified, but I currently suspect that one of the shocks is not working properly and I'll send it back this winter if it's bad. When I changed the oil, one shock was notably stiffer than the other. Damping is still much improved and I sometimes think it could be even better--maybe if that second shock were pulling its weight, it would be perfect. It is worth noting that on the Limited, the rear shocks are identical to the fronts except they have only one arm instead of two. The valve body is identical and it is secured to the frame, not the brake backing plate, which is why they're unique.

 

Up front, I still have ISO 32 oil in the shocks. My first instinct was to put in some thinner oil thinking that the wheel/tire assembly wasn't moving fast enough in response to a bump. I ordered up some 5 weight motorcycle shock oil which is the thinnest stuff available. I haven't changed it yet, mostly because I'm now thinking about MORE damping, not less. I do not currently believe the impact harshness is because the shocks are so stiff that the wheel/tire assembly is immobile when it hits a bump, I think it is because the wheel/tire is permitted to move TOO MUCH and continues to move around even after the bump, causing the secondary vibrations that rattle the steering column. So now I'm thinking that heavier oil in the front shocks will help damp the wheel/tire assembly much better. It was a HUGE improvement in the back, passengers or no passengers, without any increase in ride harshness or impact sharpness. I think after testing air pressure in the tires, thicker shock oil should be the next step. 

 

I am not sure if the front springs on my car are too firm, but I don't think so. The front end bounces pretty easily when you jump on the bumper and as I said, 90% of the time, ride quality is excellent. It's  the large, single, staccato bumps that really upset the car. That's why I think about replacing body mount bushings and new weather seals and things like that in an attempt to stop the crash that runs through the entire body. Maybe that's caused by secondary rebounding of the front wheels when they hit a big bump. 

 

This is a lot of words and mostly me thinking out loud. I'm willing to believe it's the tires, but the radials didn't create the crash and nothing I've upgraded has changed it much. I do know that the shocks were shot when I got the car and it got A LOT better with the shocks rebuilt (a much greater difference than any tire change).

 

We'll experiment with tire pressures and oils and see what we can do. Thank you for the awesome expertise, I hope this is helpful for others as well!

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Benefits of AACA Membership.

As for gas charged shocks 70's marketing, yes as pressurizing most fluids increases the boiling temperature and same would be true of shock fluid though in the case of road shocks no significant risk of boiling but more gas pressure decreases the likelihood of cavitation (which in effect is boiling but in a different manner) during use thus aerating the fluid decreasing it's effectiveness.  

 

As for the rest of your thinking out loud

 

Basically you can boil it down to three areas of experimentation

1. Springing ( in the form of actual springs, spring rate of the tires (which can be adjust down with less air pressure and up with more)(and the tire construction itself creates spring rate) and in theory gas pressure of the shock though not adjustable on road cars typically.

2. damping which as you will not be altering piston design is only controlled by fluid viscosity in this case. I believe the shop manual spec's a oil to use you may want to determine the factory viscosity is what the engineers of the time designed the system around

3. Mass - so weight  of the system. As Willie noted the tires may be adding significant amount of unsprung weight effecting the spring mass damper system.

 

You change any one of these: spring, mass, damper you effect the ride handling.

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Doing some checking, the Hercules 7.50R16LT radials weigh 38 pounds each. The 750-16 Firestone bias-ply whitewalls weigh 32. Six pounds is not insignificant. I did not run tubes in the Firestones, so that's a non-issue.

 

Both the load range D radials and the Firestone bias-ply tires are advertised as "8-ply." Since the construction type is different, I don't know whether this is an apples-to-apples comparison. Unlikely.

 

Comparing the relative stiffness of the sidewalls is probably not possible. The Hercules radials are LT tires (light truck) so they're thicker in every way than a P-metric (passenger car) tire. There is surely some additional sidewall stiffness because of its construction. Less air pressure probably won't hurt anything, although it will generate additional heat at highway speeds. 

 

1795432669_IMG_20160817_1308464691a.thumb.jpg.a72fcc292743546d42c13aca9321cdbd.jpg

 

Doing a little more looking, it seems that any radial is going to be slightly heavier-duty than any bias-ply tire. Even Diamondback's new Auburn radial has what appears to be a D load rating, which is ~2400 pounds. That compares with the bias-ply Firestone at 1660 pounds. The Limited weighs about 5000 pounds.

 

The Limited's wheels are unique, but I'm going to see if perhaps that Packard's wheels might bolt on to the Buick. Probably not, but a few measurements will tell me and then perhaps I can try different combinations and see what the effect might be.

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 My '50 has essentially the same suspension as the Limited, I think.  It, too is a little harsh on some "bumps".  I did not remove and clean the inner A arm  bushings. Sure wish I had. I am not sure if I cleaned the lower outer ones. Outer uppers were cleaned  when removing/replacing the shocks.   So what am I  saying?   Wondering if the lube is getting to the entire bushing, or just bypassing and exiting the side away from the zerk,  giving false assurances that the bushing is well lubed?

 

  Ben

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Tim works fast! Dropped the car off yesterday (Saturday) and just got word that it's ready to go. I'll pick it up tomorrow and we'll see how it sounds and then start doing some suspension experiments.

 

I guess I should get back to work on that Lincoln sooner or later, too...

 

And the '29 Cadillac needs fuel lines and leaf springs rebuilt...

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2 hours ago, Matt Harwood said:

Tim works fast! Dropped the car off yesterday (Saturday) and just got word that it's ready to go. I'll pick it up tomorrow and we'll see how it sounds and then start doing some suspension experiments.

 

I guess I should get back to work on that Lincoln sooner or later, too...

 

And the '29 Cadillac needs fuel lines and leaf springs rebuilt...

 

 "No rest for the wicked"  I have heard.

 

  Ben

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Picked up the Limited from Tim Shaffer at the exhaust shop this morning and as pleased as I was with the first round of exhaust upgrades, I am just as pleased with these modifications. The car is nearly silent with the addition of that second little muffler at the back. The idle, which was already pretty muscular, has taken on a deeper baritone sound but is quieter, so it sounds wonderful. There's a video below but it's so quiet that you can barely hear the idle above the ambient noises. Nice!

 

On the highway (of course I had to test it) the drone is COMPLETELY gone. You can't even hear anything but the wooshing wind anymore, and maybe a little bit of that noisy fan belt singing, but that seems to be getting better. The drone, which sounded like a bad wheel bearing rumbling along, has vanished. Very pleased with that.

 


Tim also changed the pipe going over the axle so it won't be in danger of bottoming-out ever again. Beautiful work as always, and he only charged me $150. The guy is superbly talented and very reasonable. If you ever need exhaust work in Ohio, I can't recommend him highly enough. He's an artist of the highest order!

 

ExhaustFinal1.thumb.jpg.8cabbc139ca4c27ac370dc391a72677c.jpg  ExhaustRev2-1.thumb.jpg.bd3bb7a8adabb9ad81d5229817c08cc4.jpg

Before and after of the over-axle pipe.

 

ExhaustRev2-2.thumb.jpg.24c8dbf52b407ef085f814d2c6ed10f7.jpg

Mini muffler installed. I think it's too shiny, but it

isn't very visible unless you're under the car. I may

paint it hi-temp satin black anyway.

 

And as I pulled into the parking lot this morning coming back from Tim's shop, I found this waiting for me, fresh off the trailer:

 

51RoadmasterWoody1.thumb.jpg.4caca410149afec673b2d7d7ecbc1e79.jpg

 

1951 Buick Roadmaster 79R wagon. A real-deal one owner all original car with just 59,000 original miles. Totally untouched time capsule of a car and a desirable big series wagon. I mean, it still has its original T3 headlights! Starts and runs effortlessly and sounds like a sewing machine with those hydraulic lifters. So smooth! We're going to service it and then I'll get better acquainted with it. New arrivals are always exciting, but I've been expecting this car for a while so it was a very pleasant surprise to see it in my parking lot when I arrived this morning. Too cool!

 

20200701_105311a.thumb.jpg.a2d05b3c895c964e8eb075e3f25d7915.jpg20200701_105421a.thumb.jpg.ed027d0297ea56b9285aebae16efe020.jpg

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Just noticed the speedometer reads to 110 mph like Buick did in 1940.  But, Buick changed the speedometer to read to 120 beginning in 1941.  Why the flopping around?

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Matt.....it can take endless amounts of time and money to get a car right......but once it's done, you never have to pound your head against the wall ever again. Then you have the "new" problem...........time goes by faster than you realize, and milage adds up......all of a sudden you realize its been five years and you haven't touched a thing except air in the tires........been there, done that. It's time to enjoy the car with your family.......

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On 7/1/2020 at 3:20 PM, edinmass said:

......all of a sudden you realize its been five years and you haven't touched a thing except air in the tires........

And then about 10-12 years you get to do a lot of it all over again.

 

I always liked dad's mentality of car purchasing:  "is that a serviceable product ?"

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Posted (edited)

Took the Buick and Melanie's Chrysler to a 4th of July car show that a friend asked us to attend. No problem. Easy drive there in the morning on surface streets, 35-45 MPH. Car stayed nice and cool even though temperatures were already well into the '80s at 10 AM. Show was decent, although it was filled with mostly garden-variety stuff and  a bunch of home-built hot rods. We stayed for about three hours but it just got too hot so we headed home with temperatures in the low '90s. Buick was fine, showing about 195 at long stop lights but 180-185 on the roll. That seems to be normal now. And now that I'm paying attention to the ride, I feel that the front end is VERY floaty. I wasn't paying much attention, but now that I am, it feels like the front of the car is bobbing up and down all the time. More [anecdotal] evidence that I probably need thicker oil in the front shocks.

 

About half way home we ran into some construction and there was one of those steps in the pavement between the old surface and the new area where they're working--you know, one of those cliff faces about five inches high. Ka-BOOOM! I thought both front tires had exploded. A new significant thump under the car presented itself afterwards, so we hustled home and parked it. No visible damage to the wheels and tires, but man, that was a hard hit. Maybe I should be glad for these heavy truck tires. 

 

This afternoon I put the car up in the air and poked around underneath. Nothing visible damaged or loose. I found a few loose fasteners, like those holding the front fender speed ornament in place, but I doubt that's a source of such a big rattle. I used rubber hoses and wrapped the brake lines that run along the trailing arms to the rear brakes, as they seemed to be making one of the "small loose part" sounds. Still not the source of the loud thump that started with that big bump yesterday. Hmmm...

 

Then I noticed a sliver of light in the right rear wheel well that I hadn't noticed before. Looking closely, I saw that the fender skirt's forward hook was just barely holding on to the fender. By shaking it a bit, I could cause it to make something akin to the booming sound I heard. It appears that a combination of the fender edge being a bit flexible and that massive bump allowed the bracket to work itself loose. I'm glad it didn't fall off while I was driving; it was just barely holding on by a thread.

 

7-5-20-1.thumb.jpg.aad81424bee1da2af08241767545fbf9.jpg  7-5-20-2.thumb.jpg.0df78899d9fe8f38476c7d8fa2cf3408.jpg

Things moved around enough at the fender skirt's forward bracket

mounting point that it was just barely holding on.

 

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Here's how it should fit.

 

The metal of the fender is in good condition, but obviously my rubber gravel guard is coming apart. While taking these photos, I noticed that the gravel guard doesn't even hug the contours of the fender very well, leading me to believe that it is for a Super or Roadmaster, whose fenders are much more rounded in this area. I've been aiming to replace them anyway, but a set of new gravel guards is more than $500. Ouch. I've been putting it off for obvious reasons.

 

Anyway, I assumed that the fender skirt's bracket would be adjustable, but it was solidly riveted in place. I drilled out the rivets and re-positioned the bracket so that it would pull the fender skirt tight against the fender (you'll recall I installed new fender skirt gaskets last year). Interestingly enough, the bracket is slotted like it's supposed to be adjustable, but the holes in the skirt only line up one way, so there's no point to the slots and no real adjustment. Instead, I just tack-welded the bracket in place--as strong as the rivets, semi-permanent, but removable if I need to adjust it in the future. Once the welds cooled, I painted the area black and reinstalled the skirt. Voila! Tight fit that's far more secure than it was before.

 

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Before and after: I drilled out the rivets and relocated the

bracket to hold the skirt tight to the fender. 

 

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Cleaned the bracket and tack welded it in place. Ground the welds a bit and painted the area.

 

 

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Now the skirt fits tightly  and is no longer in danger of falling off. You

can see how the shape of the gravel guard isn't even close to the shape

of the fender. I guess should spend the money to replace them.

 

As long as I had the car up in the air, I removed the rear shocks and re-tested them on the vice. I believed one was a little limp but both seemed to be working properly. I topped them up with the ISO 100 oil, and the one I thought was weak took a little more, so that may have been the problem. Removing and installing the rear shocks is not a big job, although it does take a bit of muscle to shove the heavy shock into the frame and hold it in place while you line up and install a bolt from the outside. A bit of work, but all good. 


Tomorrow I plan to drain the front shocks and fill them with ISO 100 oil as well, hopefully improving ride and handling. Will report back when I have results...

Edited by Matt Harwood (see edit history)
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Posted (edited)

So tonight my plan was to change the oil in my front shocks. According to the guys at Apple Hydraulics, there's ISO 32 hydraulic oil in there, so my plan was to suck it out with my little vacuum pump and fill it up with some ISO 100, same as I used in the rear shocks. Step one was opening up the fill plug on the driver's side shock, and even though these shocks were "rebuilt," the plug was a little chewed up. That seems odd--I know I didn't chew it up, especially since it's just a 7/16" hex head. Anyway, I managed to get the plug out and cleaned up the flats with a file so a 7/16" socket would fit easily, like it should.

 

Then I spent some time making some little fittings for my vacuum pump, tapering down to a tiny plastic capillary tube about 1/16" in diameter, which I figured would slide into the depths of the shock body and suck out that thin oil. So I did just that--I snaked it down in there and turned on the pump. Then I waited. And waited. And waited. And no oil came out. I checked the suction by putting it in a cup of water and sure enough, it sucked up that water with no problems. Hmmm...

 

At this point I figured the worst and grabbed my little oil can full of ISO 100 oil and started pumping fresh oil into the shock. A few pumps, then I bounced the car up and down to move the shock valves, a few more pumps. Repeat until the little oil can was empty. Refill and continue until the little oil can was about half-empty again. Once the oil started bubbling up through the fill opening, I figured it was full and reinstalled the plug.

 

I didn't get to the passenger side since tonight was family dinner night and the passenger side is particularly difficult to reach, but I'm wondering: did they forget to fill my shocks when they rebuilt them or did they rebuild them poorly and all the oil leaked out? There were trace amounts of oil around the shock on the frame, but I can't be sure that it was fresh and it wasn't a lot--certainly not enough to fill a large shock. I don't think I would have installed the rebuilt shocks without cleaning the frame, so I'm leaning towards my expensive newly rebuilt shocks are leaking, just not quite as badly as before. 

 

I cleaned up the area around the shock with brake cleaner and some rags so I'll be able to see if it gets wet again. I'll change the oil in the passenger side shock tomorrow and we'll see what we see.

 

Who else rebuilds shocks beyond Apple? I suspect we're headed into the "guess we'll just throw money at the problem" stage once again.

 

 

Edited by Matt Harwood (see edit history)

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31 minutes ago, Matt Harwood said:

 

Who else rebuilds shocks beyond Apple? I suspect we're headed into the "guess we'll just throw money at the problem" stage once again.

 

 

5 Points did mine

https://fivepointsclassicautoshocks.com/

 

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58 minutes ago, 38Buick 80C said:

Highly endorse these guys, they rebuilt mine.  I had also asked them to photograph the shock fully disassembled so I could see the guts and learn where the wear points were.  I asked them questions and came away very satisfied that they were indeed working on my shocks and doing them correctly.  I've heard your complaint about AH from others as well.

 

 

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Sidenote:  I know $500 is a lot for the rubber gravel guards, but with certain things like these I tend to get them while the getting is good (not something you want to find out is discontinued in reproduction when you want them).   Same argument applies to hubcaps, emblems, lenses, plastic interior parts, certain die cast trim pieces, limited run mechanical parts that are know problematic, and ...  

 

The 1939 LaSalle was really frustrating to do as many of the more specialized parts were in the realm of very ancient people who were also very retired - and we were trying to do car on a business schedule.  It all came together, but the timing was dicey.  That said, it sounded like the fellow who made all the dash plastic died while sitting at his workbench putting my parts in the box to ship to me (his family could not been more helpful though).  And, a fellow who made me a couple RR PI parts got lost via his Alzheimers on his way to the post office and took a day to find him (again the family could have not been more helpful). 

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In the Ka-Boom department - I will always recall the story of a friend who had the spare tire of his 50 Packard explode and shoot a poorly installed radio speaker into the back of his head - he was in the middle of nowhere and fortunately ran off the road and there was nothing to hit  (more or less - the car eventually was stopped by a fence post while moving at idle) 

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In the 1941 Buick, the ka-Boom department was usually caused by bottoming out of rear shocks.

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Driver's side shock and the surrounding area are still dry so it's not leaking seriously, if at all. I guess a long drive will tell us for sure.

 

I tried to service the passenger front shock tonight and got mixed results. One, the filler plug is hidden under the heater plenum on the front fender, a Limited-only problem. I was able to get it unscrewed with a small ignition wrench and it was a different type of plug than the driver's side, but whatever. I tried my little vacuum pump and fed the capillary tube into the shock, but again, it wasn't able to pull any oil out. I tried filling it and it took one or two pumps of oil from the can, then started overflowing when I bounced it. So that shock was full. I sealed it back up.

 

It's pouring rain tonight so no test drive, but I'm hopeful that ride will be significantly improved just with oil in the driver's side shock. Not sure if there will be any issue with light oil in one shock and heavy oil in the other, but I'm curious to see how it feels on the road. And hopefully the big thunk under the car is gone, too.

 

Maybe it'll be dry in the morning and I can try it out.

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Matt......did you buy a set of chassis ears?

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10 hours ago, edinmass said:

Matt......did you buy a set of chassis ears?

 

Sure did! Sitting here next to my desk as I write this.

 

ChassisEar.thumb.jpg.3d5f05eb6e872217466c18c0ac8a7e8b.jpg

 

Drove the Buick to the barber shop this morning. There was a terrible noise coming from somewhere ahead of the firewall as I drove, mostly at higher RPM. A grinding, whizzing sound. Totally RPM dependent, depressing the clutch at speed stopped it, so it was definitely engine not clutch or driveline. Drove fine otherwise but I was assuming that something else was knocked loose and was hoping it wasn't something like the fan or throwout bearing or generator. Got back from the barber shop and took a look under the hood and found that the air intake tube--which I moved to access the driver's side shock--was touching the fan belt. Repositioned it and cured the problem.

 

At that point I spiked the football and went inside. A win is a win, right?

 

Ride quality may be improved, but it's still inconclusive. Not dramatically better, but probably better because the secondary reverberations are largely gone and the steering wheel doesn't shake as much. I'll need to drive it home and hit that expansion joint on the bridge to my house to really know whether it's significantly improved. In fact, I find myself wishing for even more damping, as it still feels a bit floaty. The big booming rattle is gone--it was surely the fender skirt. There are two unfamiliar rattles now, but I don't know if they were always there and masked by other sounds or if they're new. Chassis Ear to the rescue! I'm eager to try it out, maybe tonight or, more likely, on Saturday before a day tour on Sunday. Looks like an awesome tool, can't believe nobody thought of it sooner!

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Although the weather was crummy this morning, it cleared up this afternoon and I was able to do some experimenting with the Chassis Ear. What a great tool! I started by putting the car on the lift and clipped the six mics to areas where I suspected rattles were originating--for the record, repairing the fender skirt seems to have cured a big one. I ran the wires safely away from moving or hot parts and connected them to the control unit on the front seat. Although the video below shows me driving with it broadcasting through the radio, that was just to demonstrate the system.

 

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Chassis Ear mics have sturdy clips that hold them in place, nice long wires, and

a self-contained battery-powered control head that's easy to operate. 

 

For actual testing, I used the included headphones which really do let you hear every little detail. For example, I could hear when the clutch started to grab and the meshing of the gears in the rear end (surprisingly loud, but I don't believe it's something to worry about--the mic surely makes it sound worse than it is). Using the worksheets to label which mic was attached where, I was able to identify places where I thought there might be rattles: rear splash apron where the back-up light post touches the bumper bracket (red), the two spring-wrapped brake lines that stretch down the control arms on the rear axle (yellow and blue), the E-brake equalizer just under the differential (pink), the fender skirt (green), and the heater unit under the B-pillar (white). 

 

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Under the rear bumper--you can see where the back-up light

mounting post touches the bracket. This was a definite
YES for rattles.

 

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The two spring-wrapped brake lines. I suspected these were the

source of a "chhhsssh" sound over sharp bumps. The left one
is still a suspect, right one is quiet.

 

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E-brake equalizer. I wasn't sure there was sufficient slack

in the cable to allow the equalizer to hit the housing, but

the Chassis Ear revealed it was doing just that.

 

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Just to be sure, I clipped one to the right rear fender skirt area.
You can really see how poorly my gravel guard fits here.

 

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And one near the heater assembly, which is in need of repair

and offered inconclusive results as to chassis noises.

 

7-11-20-10.thumb.jpg.045fe836fd07a3f07da1cf3e240094db.jpg  7-11-20-11.thumb.jpg.c484c4ebd98e37b3ff8ab03d3b2b84a8.jpg

Connected the wires to the control head on the passenger seat,

plugged in the headphones, and started testing.

 

Once everything was connected, I started driving. I chose the roughest section of road near our shop and made the 1/2-mile drive back and forth on each channel to be sure I was getting all the rattles. Fortunately, it seems that most of them are gone already, the biggest offender seems to have been the fender skirt. A few others are still present and are mostly encouraged by quick, small bumps, not larger ones. I keep going back to the tires, and I'm going to try taking 5 PSI out of each of them to see what happens. There's still a bit of impact harshness, although now that the shocks are all topped off with thicker oil, overall ride quality has definitely improved. I think I can feel that the right front shock has thinner oil, but that might just be the placebo effect. It rides well nevertheless.

 

There's a lot of ambient noise that the mics can pick up that you won't hear ordinarily. I could hear all kinds of things that were just the car doing its thing and the metal chassis was transmitting sound from all corners. As I mentioned, the most notable one was the rear axle, but I could also hear the transmission, the exhaust, and the brakes. But what I really hoped to hear were sharp, staccato sounds that indicate a loose part moving at high frequency, AKA a rattle. Through the Chassis Ear, loose parts would surely sound different than to my naked ear, but the presence of a quick, sharp sound would suggest a rattle. After testing each channel, I evaluated what I heard using the check sheets that come with the Chassis Ear:

 

7-11-20-4b.thumb.jpg.6c9e94f238594d4f343b82c4248e355f.jpg

My shorthand: X means I believe there's a problem, a check

in the "Good" column obviously means it's OK, and a circle

means inconclusive. 

 

7-11-20-4c.thumb.jpg.8ad47c15ab1ae4b9023db55c8d55683b.jpg

I am amused that they put "the professional" in

quotes. That sums me up, I think. Professional-ish.

 

Once I had taken all my test drives (which added up to about six miles) and evaluated what I'd found, I did some basic noise abatement on the areas where I was fairly certain there were problems. The rear splash shield was definitely bouncing around, so I installed some rubber hose on the bracket to keep it from vibrating. Whomever installed the back-up light drilled that hole in exactly the wrong spot--right above the bumper bracket. There's just no clearance there and the back-up light was actually touching the bracket. The weight of the light would make the sheetmetal splash apron bounce every time the rear suspension hit a bump, then it would clank back into place. 

 

Then I tightened the E-brake cable a bit. Not too much because I don't want the brakes dragging and my E-brake works very well, but just to take out a bit of slack. Again, I added a bit of rubber hose on top of the U-shaped bracket so that if it does bounce up and hit the differential, it won't be metal-to-metal contact. I also added some hose to the brake lines, which are wrapped in protective springs. I think they are vibrating or buzzing, so the hose should attenuate some of that. Another test drive and it was a bit quieter. There's still something in the front suspension and an overall boominess on some larger bumps, but I'm sort of thinking it's just from this thing being a big, hollow metal box moving across an imperfect surface--some interior sound-deadening materials next winter will help with that, I'm sure. My clutch pedal started making a clicking noise along the way, too, so I'll have to take another look at the linkage under there--both the brake and the clutch pedals seem to make a noise that the chassis ear could detect. They're not loose, but maybe there's something in there that's out of alignment or maladjusted.

 

I also made a brief video to demonstrate the system. I connected the Chassis Ear to my Redi-Rad and played it through the radio so you can hear what's going on. Not ideal for diagnostics, but it gives you an idea of what the chassis ear does.  I think I tested it using the mic on the E-brake equalizer, which was by far the noisiest channel. Hope this is useful for someone else!

 

 

Thanks to my friend Ed Minnie for turning me on to the Chassis Ear. What an awesome diagnostic tool for someone who gets nutty about rattles like me! And it's kind of funny--I was driving my Cadillac CTS home afterwards and realized that the driver's seat creaks and groans and I don't particularly care. But one tiny click or buzz in one of my old cars? Maddening! 

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Posted (edited)

I have had a set of chassis ears for over twenty years. My new one is blue tooth so no wires. My old one is identical to Matt’s unit. Trust me, if it rattles you will know it. Long story short......on day I fixed a customer car......complaint was a “noise”. I fixed the bad ball joint about to fall out of the car. Turns out that noise was OK with the owner......they wanted a rattle fixed. Lesson learned. Test drive every noise complaint and ID the noise the customer wants fixed. The chassis ears over time paid for themselves tenfold. You just need a busy shop to justify the cost. They work great for modern wheel bearing noises, you can figure out which one.......often times a car will have two bad wheel bearings. You learn over time using the tool what is too much noise, and what is fine. I have found side mount rattles, trunk rack noise, exhaust system contact, , ect using them. They are a great tool. Matt.......you need to buy a KV ignition tester next. 😎

Edited by edinmass (see edit history)

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Just a brief test drive after doing some rattle abatement. I ran it harder than usual just to show off a little, but it never seems to mind. This sucker pulls hard and just whisks along. And now that it's quiet and almost entirely rattle-free, it's really a pleasure to drive. I really enjoy driving this car more than any other. What an odd thing to love.


Now if I could only get that fan belt to quiet down...

 

 

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