40's rearend gears

[Jyrki]

Anyone know which model years of rearend gears interchange with my 46 Roadmaster? Fred Rawling told me that at least those from 1937 to 53 interchange, but how about 54-56?

[Guest]

My parts book only list as far back as 53 on the gears, although I have heard of putting later 3rd members in earlier cars to boost things a bit...pinion brg is same 40-55..beware as 55 they changed that puppy..rear pinion brg is same and Buick farm has a few, side brgs, I would again look at Buick Farm and if no luck, go to OlCarBearing in N.C., he had my stuff for my 55....My parts book shows 4 different gear ratios for 53-6, 3.4,3.6,3.9 and mid yr 55 they boosted the 3.4 to an actual 3.42, the reasoning was better gear mesh, these sets are identifiable by nuts holding the 3rd member to hsg vs. bolts on the others, the hsg is beefier too to help with the torque...this is from my 55 product svc. bulliten book...<BR> If you do go with the later 3rd member/driveshaft, let us know how things go....I am still with a shortblock awaiting the correct pistons...<P> don55

[critterpainter]

Freds information sounds about right.<BR> I have helped change out the "pumpkin" in a couple of 48 supers to get a better gear ratio. The hardest part was changing the driveshaft as it is pinned to the pinion gear in addition to being splined, and can be quite difficult to get off. <BR> Bill

[The Old Guy]

I have a 55 Century rear end in my 40 and I love it! The rear ends from 40 through 55 will interchange,even the side gears have the same spline ,so the axles will all fit with no problem. My 40 had a 4.40 axle and it was winding way to high on the interstate,so I put in the 3.42 and it works fine.

[Jyrki]

Thanks for all the info. The more I know, the more I seem to doubt if changing gears is worth it (provided I'd even find a suitable set). I have now understood that separating the pinion and driveshaft is rather tricky, so maybe I'd better settle with the high-winding 4.1:1 gears, unless I'm able to find a complete 50's axle with decent gears to swap into. <BR>Thanks again,<BR>Jyrki<BR>Finland <BR>(we have -70F right now, in case you were wondering)

[The Old Guy]

Finding a complete 50s axle will still leave you with the drive shaft problem. The only way you can put a complete unit in ,is to find one with the proper length drive shaft and torque tube

[Jyrki]

You're right of course. Somehow it didn't came to mind. Since the axle is hung by the tube and trailing arms, I quess a plusminus 1/2" variation in lenght would be tolerable, as the springs, shocks or panhard bar wouldn't mind it. However I think I'll leave this subject to be considered again once the car is otherwise completed...

[Fred Rawling]

It was my understanding that 54 and 55 ring and pinion was a bolt in situation on earlier carriers but that you needed the 54-55 cover for some reason. Does anyone have any info on this?

[palbuick]

In my 40 Century, I discovered that I had a 54 Dynaflow ring and pinion gear, can't remenber the ratio, and I believe that it has the 54 cover.<BR>The hardest part will be finding a rear end, with a good ratio.<P>Jim Schilf / palbuick

[Jyrki]

I purchased a good set of 3.42 gears (12-41 teeth)from Wheatbelt Antique Auto. It appears this set came from a 1955 Buick. So, now I'm asking you once more, what do I need to make it fit my 1946 Roadie? Do I need different pinion bearings? And what do you guys actually mean when you say I need a "cover" from a 54-55 rear? Thanks in advance!

[Guest]

By cover I think they mean the half spherical cover that bolts to the back of the diff housing.<BR>For bearings I thnk you would have to pull out the old gears / bearings and carefully measure both.<BR>Good luck<BR>Allan

[Fred Rawling]

I was told that the cover plate on the back of the carrier was deeper on 54-55 than on the earlier ones. I have not been able to verify that. The biggest problem that I had in changing the ring and pinion in my 50 Roadmaster was seperating the pinion gear from the drive shaft. The second most difficult problem was getting the run out at the transmission end of the drive tube to factory specs. I had to take it to a drive line service because I could not get it right with what I have to work with.<P>Another problem that surfaced was a leaking torque ball. There is a section in the shop manual that tells how to adjust it but it is in the standard trans section and I never saw it. If it is not adjusted correctly, it pumps trans oil out.

[Guest]

Jyrki<BR>This may interest you <A HREF="http://www.aaca.org/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=2&t=002132" TARGET=_blank>http://www.aaca.org/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=2&t=002132</A>

[Jyrki]

Attention everyone! I just measured the 46 pinion bearings, and it appears that the rear (roller) bearing of 1955 is 0.08" wider than that of 37-54. Both the ID and OD are same. Moreover, the front pinion (ball) bearing of 1955 is otherwise the same as 37-54, but the pre-55 bearing is a sealed type (to prevent oil from flowing into the torque tube?), while 1955 is unsealed for some reason. <BR>I could not find a supplier for the 1955 REAR pinion bearing, but I can use the narrower 37-54 bearing - I just have to use the spacer between front and rear bearings from the old pinion.<BR>The ring gear: both the old 4.10 and the new 3.43 ring gears have 41 teeth - the difference is in the pinion - 10 vs 12 teeth. I had to drill the rivet holes in the carrier a bit larger to accept 3/8" UNF bolts of the new ring gear. Anyone with a newer shop manual please let me know the correct ring gear bolt torque - my 1946 shop manual only tells how to use rivets...<BR>Once I get the new bearings, and are able to proceed, I will let you know how it turns out.

[Guest]

Hi <BR>Have you got any bearing numbers from the bearings?<BR>Somewhere I have an old Timken bearing book.<BR>Cross reference interchange numbers between manufactures are also avialable.<P>While both ring gears may have 41 teeth they could be machined slightly different to match the pinion gear. <P>Good luck<P>Allan

[Jyrki]

Allan, I don't have the numbers on hand while reading this forum, but I will look up for them when I have time - we just got a baby girl last night

[Fred Rawling]

My 1950 shop manuel says to rivet the new gear to the carrier. There is nothing about bolting it together. I do know someone who put a 1950 gear un a 1937 and he bolted it in and it worked fine. I do not know what torque he used.

[Guest]

I lost my computer's hard drive, no backups anywhere, all gone, guru's say $1000 to purge it manually. No way. Now I'm back with a new hard drive, but have lost all my pics, files, emails, addresses, links, everything. I remember just before my PC went down, Fred Rawling asked me if I'm interested in a canister filter. I lost your mail and address, so I'm replying here. Thanks but I think I will try to make a better oiling system. I have an extra "remote filter kit" from Summit, and will try that. I got a NOS 1946 Owner's Manual Package from Buick Farm, and it says nothing about changing the filter nor cleaning it, and in the pics of an engine there's no filter. So I would say that 1946 models came without filter.<P>By the way, who's the webmaster? Now that I have all software re-installed, thi darn forum asks me to login all the time, then "thanks for logging in", only to find I'm not a registered user, which I am.

[Guest]

Allan, are you able to find a cross-reference for a Hyatt 1529T ?<BR>That's the 1955 rear bearing.<BR>How about New Departure 5607, or 5307, or 5307WM ?

[Jyrki]

Finally I'm in a dead end. The 1954-55 ring & pinion are not a bolt-on swap to an earlier axle. The pinion gear is too large in diameter to fit. So you'd need the complete carrier (third member) from a 1954-55 Buick. For instance in my case, the 55 pinion gear is some 0.63" larger than my original, thus the ring gear needs to move 0.32" away from the pinion. The differential side bearing webs won't allow that much side movement. So I wasted $300 on a gearset I can't use.