Jump to content

3.90 rear gear assembly for Buicks


Recommended Posts

I know this set will fit ‘37’ and ‘38’ rear ends.  I pulled it from my ‘37’ coupe.  I changed mine over to a 3.41 third member from a  ‘54’  century or roadmaster.  This is a factory matched set (must be) for quiet operation.  I know this has very low use - long story.  

Link to post
Share on other sites

BTW, I love the 34 / 35 design that Biick had.   Is yours a sedan or coupe ?   I’d love to see it.  Where are you located.  I’m in the Tamps / St Pete area.  Roght now I have a ‘37’ and ‘38’ coupe.   I have this thing for two door cars.    Oldbuickjim@ gmail.com. 

Link to post
Share on other sites

I now have two different solutions to the problem.  My first is the Borg Warner over drive.  The second is to replace the third member with a later rear.  The first has just become more difficult because Lloyd Young passed away early in January.  I am trying to find out how to gather up his stock  of OD’s and items he produced to adapt the OD to our Buicks.   That was a reasonable option.  Plus, the OD provided a nice spread of gearing with the OD making a ‘fourth’ gear for crusing.  The second is adapting a later rear end in place of the 4.44 rear ends.  I just finished changing the rear on my ‘37’ Buick.   This change is more expensive as machining is required.  But I  used the original  1937 banjo housing and axels.  The next  mod would require finding a 1940  or later rear  ( I am not accurate on the year)  with a 3.90 or better - 3.6 rear and swapping the complete rear.   Mine is a ‘54’ rear with a 3.41 ratio.    That also may require  mod’s to the torque tube and drive shaft.  I used a ‘54’  third member, machined the housing and modified the torque tube and drive shaft and put it in my ‘37’.  I know that works very nice but more expensive than the OD I put in my ‘38’.   

         I should probably should start a seperate  line with info and  answers to questions on how to solve the high 4.44 rear ratio for todays cars..  e-mail me at. ‘Oldbuickjim@gmail.com.    

  • Like 1
Link to post
Share on other sites

My 35 is a four door sedan with the trunk and rear spare tire carrier. Its currently being stripped down to bare metal and repainted, I'll be soo glad when its finished. Last time it was done was in the mid 70's. I live on the east coast of Fl.just south of Titusville. Many someday you can do or help me with my rear end. Thanks, Greg.

Link to post
Share on other sites
On 2/10/2018 at 8:28 PM, Jim Nelson said:

$500 plus freight.  Are you familiar with rear ead swap’s? 

Jim, I just sold a third member assembly w/3:60 gears and all new bearings/seal/spyders, plus the axles for $500(to cheap?) It went to Amsterdam..

Link to post
Share on other sites

I spent $500 on getting the complete '54' rear.  Then, about another 100 for bearings etc.  So I think I had about $600 in my costs.   I drove to the Atlanta area for the rear.   You get what you can where you can.   I wanted the 3.41 ratio.  I could have gotten a 3.6 from other car rears.   The 3.41 was not as available.  ( 1954 road masters and centurys with Dynaflow had 3.41 rears,  most were made that way.  You could get the 3.6 with a stick tranny).    So began the transition to automatic trannys over stick's.   I always had standard trans until my last car  - got an auto.  Don't like it at all.   It shifts when it wants to and not when I NEED it to  :-((

Link to post
Share on other sites
On 2/10/2018 at 9:40 PM, tyler searle said:

Been reading up on it some. Have a '38 Special so this will fit, correct? I'll contact you tomorrow and see if we can work something out . 

 

  I'm up past my bedtime and will soon stop making any sense.

 

  Tyler

 

Link to post
Share on other sites
On 2/10/2018 at 9:40 PM, tyler searle said:

Been reading up on it some. Have a '38 Special so this will fit, correct? I'll contact you tomorrow and see if we can work something out . 

 

  I'm up past my bedtime and will soon stop making any sense.

 

  Tyler

 

I have a 38 special also, built on a 45 frame. It shoots tombstone bullets but can also take smith and wesson longs.

Link to post
Share on other sites

Buick35,  IMHO,  the easiest way to change your rear to a more comfortable ratio is to replace the rear completely.   That is a long way to get there but I  think early Buicks (36 and earlier) would need to do it that way.  IF we can get someone to pick up Lloyd Young’s  over drive systems, that would be the easiest mod.  That way you can have youe cake and eat it to.   Time will tell.   Changing the third member and mod of the torque tube drive works but is a bit more expensive.  Just some thoughts.  The ‘37’ rear had leaf springs so changing to that year makes it easy in that part.   Ole Bob Pipkin also moditied later rear ends by cutting off the coil spring supports and replacing them with leaf spring mounting parts.  As time goes by, the options get fewer and more expensive.  But they still are there  and we have to adjust to 2018 reality.  IMHO, I think its still worth it.  Our cars are part of history and we need to keep them where folks can see our past.  

Link to post
Share on other sites
  • 2 weeks later...

I put a 50 Special Dynaflow rear gear in my 40 Special sedan. Went from 4.44 to 3.6. Bolted in perfectly even though the torque tube was 1/4 inch longer than my original. Couldn’t see any difference in wheelbase. 50 was in a wrecking yard here in the Northwest. After washing out the third member it appears to be in perfect shape. Google Key motors. Lots of parts cars.

Link to post
Share on other sites

Wow, great change.  Others need to hear of those changes.   Having the 3.6 or 3.4 rear ends make our cars easy on the engine while keeping up with modern cars.   I put a 3.4 third member in my '37' coupe.   It required a bit more machine work but did it.   I spent more than I figured as the extra work costs more.   I had to marry the '37' front half of the  torque tube to the '54' torque tube and third member.    This way I kept the leaf springs.   Looks almost original.    I have a '38' coupe with Over Drive.  Having both that I can drive,  I prefer the over drive.  Less money and more performance sorta.  I have the advantage of the original gearing at the low end and better engine speeds around 65 (2350) mph.   I get 2600 rpm at 65 with the 3.4 swap in my '37'.  Just finished with the  3.4  so  I will start checking mpg later this summer. 

Link to post
Share on other sites

I have a friend who has two 3.90 gear sets available.  One from a Roadmaster and one from a special.   I feel JMHO that the 3.90 is the highest ratio for our old cars today.    It depends where you live and drive.   Driving 45 mph in cruise just won't work today.   If you try to go any place on modern roads,  you get run over.   OK for 1937,8,9 .... etc when roads and traffic were light but not today.   I enjoy driving to visit people and show them what cars were really like "back then".  How far things have come.   Actually, the newer cars - say -  around 2010 and forward are not my 'cup of tea'.    Personally I don't like them.  To much automation / electronics to fail.   Bought my first automatic transmission car back in 09 and don't like it.  I have been a shifter guy from my start.  (just turned 75).    I don't like the transmission telling me what gear to be in.   (The queen drives an auto shift)

Link to post
Share on other sites

Hi Kyle.  I used to run a machine shop and creating new gear set would be quite expensive.  There is not enough people who would want one to justfy machining, hardning and polishing (the area that the roller bearing runs on) and set ups to make the gears run smoothly (low noise) .  If you want a better gear set, the 3.90 set requires the least effort to get our cars running on the roads today.  I have run my ‘37’ with 3.90 gears.  It runs 55 / 60 OK.  I live in a very busy traffic area.  Even 60 mph is slow and you would be a problem much of the time.  I looked over some older mod’s where the third member is changed to a newer one.  Ratio’s of 3.6 and 3.4 are readily available.  Those swaps are not cheep (depending on the year of your car.)  but your car would not show the change except where the torque tube is altered.   I believe if you have a 40/41 or newer, changes are easier and cheeper.    I did the rear change with a ‘54’ third member giving me a 3.4 ratio.  I now run 60 mph with a rpm of ~2600 or 65 rpm @ 2750.  I have this thing that you should NOT run cruise rpm’s of over 3000 rpm.  Our straight 8 engines do not like it and will complaign.  Plus mileage suck’s.  I just finished the 3.4 rear end swap about 2 weeks ago.   I will be updating my  RPM vs gear ratio chart.  This will give you what will work best for you and where you drive.   Chart is available ——

       My ‘38’ coupe has Over Drive.  This option gives you the standard 4.44 rear to get going and after using three gears as normal, around 38 mph,  I shift into OD and accelerate up to 65 and the engine loaf’s along at 2350 all day long.  Last year I took a trip on the Interstate and local state highways for over 1700 miles with ease.  Thus, having both systems on my 37 an 38 coupes, I think I have a pretty good opinion of the advantages and dis-advantages that work today.  

          The Over Drive is cheeper but requires modification of the torque  tube to insert the over drive.   You keep the original ring and pinion that the factory set up.  Quiet and trouble free.  The over drive is the Borg Warner unit that almost every one who used a OD  uses.   Parts are available and people who know them can repair them.  I highly recomend the guy who did Lloyd Youngs units.  Lloyd has passed in Jan (two months ago) and the machinist is continuoing installing Lloyds units.  He did mine the summer of 2015.  I love the OD for my driving flexability.  Slow or fast, my straight 8 just keeps humming along.  You take or send the torque tube and third member to Glen and he will fix it and send it back to you.  Re-assemble and add the controls and electrical and you are back on the raod with minimum mess.

         More effort in swapping third member rear ends.  Machine shop work.  Not dificult but more time.  And you will probably need to rebuild the pinion bearing assembly.  Lots of fun and very educational..

        The rear end swap by changing the third member,  was more expensive.  But, it only shows the change by visual observation of the torque tube.   The interior of the car looks veriually stock.   My ‘37’ has been restored to like new ‘1937’ business coupe interior.   Nothing shows it has been modified .   

        So, those changes that are what is readily available today.   Thus, that is why I would not go to the very expensive job of trying to duplicate the 3.90 set.   I can, right now, purchase a 3.90 from a ‘54’ series 40 Buick.  Also I can get a 3.90 from a Roadmaster.  So, there are some available but in my opinion,  if I wanted to “get up to speed”,  I would go with the over drive opition.  Cost vs performance.  

         If someone wants to do the over drive now, the machinist (Glen) has changed Lloyds phone number to his in Hemmings.  We are so lucky to have someone pick up the reins and keep the over drive options available.  

         

 

 

 

 

Link to post
Share on other sites

Kyle,  So sorry that I may not have answered your question on pix desired.  Wow, where do you keep all those neat cars ?   I have pix of the 3.90 ring and pinion gears.  Also the ‘54’  third member and pinion rebuild.  I take lots of pix so I can discuss issues later.  I suffer from ‘old timers disease’ so I resemble that.  

Link to post
Share on other sites

RiKi5156B,  Like your "ID".  ? 1951 and 1956 Buick ? right?    What year did you put the 1950 third member in.   I think that in either 1940 or 1941,   Buick changed the torque tube to the two piece construction.   With that torque tube, changing the rear ratio becomes easier.  You mentioned it was off by 1/4".   That works even tho the factory calls out for   2-1/4" exposed spline shaft to go into the transmission.    The one piece torque tube prior to the two piece makes things more difficult.   Still doable.  Love it when I can go driving in my Buicks and keep up with traffic.   Interestingly, when driving my old Buicks, most cars (people) keep away from me a bit.   Some drive in formation, to just look it over.  Then off they go.

Link to post
Share on other sites
  • 2 weeks later...


I am not a machinist or a mechanic. Although I have done more work on my cars than I ever thought I could , I am still a newbie amateur.




However, I have wondered why someone does not build an overdrive from existing parts that operates constantly. It would bolt to a universal yoke across the frame. It would  attach between one of our universals and raises/lowers(?) the ratio of our stock rear ends to around 3.6. Again, I am not an engineer, but our oldies have plenty of torgue. We might have to shift a little sooner, but we would be able to cruise at highway speeds.




Just my idea..




Please feel free to tell me I just an old guy who does not  now what he is talking about..




Dwight


Link to post
Share on other sites

Well, that is what Lloyd Young did for the many years he made the adapters.  I am a fan of his.  Borg Warner manifactured almost all the OD uniys that the cars and light trucks ised from the early 30’s up until the early 50’s.  I have one of him OD units on my ‘38’ Buick.  GeneralMotors did not partake of the advantages of OverDrive like most of the others did.   Today you can utilize his design from the guy who did the mechanical work for Lloyd.  Lloyd passed back in Jan.  But, his reputation continues.  So I could use the existing rear end gearing in slow traffic and then  when I hot around 38 mph, I could engage the over drive and end up with a final of 3.11.   My original is 4.44  and that is good for only 40 / 45 mph.   Over Drives change the final by giving you a  30% reduction in engine speeds.  You need to figure if the 30% reduction gives you a final that is around 3.11 to 2.90 .   Anything below that and you would be shifting up and down frequently.   You can change the third member to 3.6 ratio which is a nice compromise.   I just changed one to 3.41 and that works nice on flat land and up to modertly hilly ground.  Thus, IMHO the OD is a verygood option.  Cost?  OD system is cheeper than the  change of the third member.   I can give you costs as such.  I’ve done both and they are in my garage right now.

Link to post
Share on other sites

I can give you my chart that shows you the speed changes for each of the  rear ratio changes from a 4.44, 3.90, 3.60, 3.41, and  3.11.   This is based on the 4.44 rear ratio used on many cars.   That my be of help.

Link to post
Share on other sites

Dwight,  If you chose to go to a OD unit, the guy who does it is a bit south of you in Circleville OH.   All you would do it jack it up and remove the torque tube with the third member attached.  Then, drive it to him.   He would take a week to two (depending on the condition of the pinion and carrier bearings) Then you would come and get it and hook it back up.  A fairly easy task for someone who is moderately talented as you seen to be.   Having a person help to move it around is enough.   You would have to remove the axels from the carrier.  That would require removing the spacer and 'C' clips in the ring gear assembly.   Again, not difficult, just different.    Having somebody provide some pix to show you each step would make it easier.    I'm working with a fellow who is changing his 4.44 rear over to a 3.90 rear.   He would be doing many of the tasks you will do.    He is located in SW New Your state.   If you choose that way, let me know .   You might  find there is some body close to you to help you with this.   

Link to post
Share on other sites
On 2/19/2018 at 11:56 AM, Morgan Wright said:

 

I have a 38 special also, built on a 45 frame. It shoots tombstone bullets but can also take smith and wesson longs.

So Morgan,  how do you have your  ‘38’ set up?   Stock or modified rear?   My 3.41 rear in my ‘37’ drives nice in fairly busy traffic.   Trying to find the sweet spot.  If I were in hilly country, I would have probably installed a 3.6 ratio.   JMHO of course.  

Link to post
Share on other sites

The rear is stock walnut. Not modified, just used a little linseed oil that's all.

 

My car, though, is a '40 special. Original rear end so the motor has to rev high, not going to change the rear because I love how it climbs hills, and with the '53 engine it can go 75 on the highway for miles without a problem, just revving like it's going 90. The '53 motor is a 263 and I'm sure cars in '53 has highway rear ends. I'm not worried, my car goes great on the highways.

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...