1938 3.615 Rear End Ratio Gear Set Available

[Only Buicks]

I am restoring a 1938 - 40C. The rear end ratio is 4.44/1 I really want to change this to a more road freindly ratio without having to cut the torque tube etc.... My understanding is finding other ratio 1938 is almost an impossibilty. Does anyone know of someone who has had experiance with having new ring and pinion gears made? I would think there would be a decent market for this type of service..... what do you think? <img src="http://forums.aaca.org/images/graemlins/confused.gif" alt="" />

[Guest ZondaC12]

ahh, this discussion has come up before... <img src="http://forums.aaca.org/images/graemlins/smirk.gif" alt="" />

i know how you feel! i got the same thing in mine. generally people like to look for the 3.9 gearset from a century, or maybe the elusive 3.6 from a '38 with a self-shifter if you can find one in a junkyard! good luck with that. i guess theres very few of em out there. i dont think anyone makes em currently, but ill bet if youve got the money...someone will do it! i seem to remember reading here that gears from a 50s buick will interchange? people who know specifically will chime in. i personally am not sure if i would want to do it! i wonder how much acceleration would be lost, or if that might also be too much load on the engine at take off. as we both know, our cars have the 248 not the massive 320 so torque is not as plentiful.

i think i still might do it someday. sure would like to be able to drop the rpms! someone with a buick torque tube needs to go to that company "gears" something or other like "gears unlimited" i forgot but they make overdrives someone needs to go and pay the exorbitant price to have a custom one engineered, then the rest of us can buy o/d's for our torque tubes cheaper! <img src="http://forums.aaca.org/images/graemlins/smile.gif" alt="" />

[mlander]

Have you tried to measure any part of the Ring Gear? I will make a guess as to the how many of the old GM cars used the same basic Ring Gear and Pinion. My guess that most if not all used the same basic setup, that is Cadillac, Oldsmobile, Buick, Pontiac and Chevrolet have the same units that are interchangeable parts. Very likely in 3 different sizes. The trick may be to find someone with a Parts Interchange Catalog first. Just how you can do this for that car I don?t know as Hemmings doesn?t have a list of people who do this service. One must also remember that these Gears/Pinions were all made on Gear machines made by the Gleason Gear Works of New York State. Since there were millions of them made even during the Great Depression and just how long they were manufactured in that particular style is also an unknown. My advice is to find someone with the aforementioned catalog.

The two firms I called <img src="http://forums.aaca.org/images/graemlins/smile.gif" alt="" />

[The Old Guy]

The 37-38 Buick club had an article in their monthly paper a few years ago about reworking later gear set to fit in the 37-38 Buick. I am sure if you contact a member of that group you will find the info.

[Guest DaveCorbin]

Dear Glenn:

You might check with Dave Tachney out in Minnesota for a self-shifter gear set. Also, there's a company named "Orf" who comes to Hershey every year. Last year, I asked them if they would need a sample (like the one from my self-shifter) to make that ring and pinion gear set. Much to my surprise, they said no, that they could make one from a different ratio gear set and diff carrier.

It's amazing what an outfit with a great measuring machine, a good set of gear cutting equipment, and a computer for "reverse engineering" can accomplish in this day and age.

The ratio is 47/13 or 3.615 in a self shifter. My 1938 Model 48 2 door will cruise at 75 with no strain. A quick math check says it's about 22% faster than your 4.44

Regards, Dave Corbin

[Guest DaveCorbin]

Dear Glenn:

I think I've got the ORF card at home, with address & phone number. We might consider trying to get together enough people for 10 sets of gears.

Regards, Dave Corbin

[Guest DaveCorbin]

Dear Glenn:

Orf is at 734-676-5520, address is Orf Corp.,8858 Ferry Road, Grosse Isle, MI. 48138

Regards, Dave Corbin

[Only Buicks]

Hi Dave,

I will give these guys a call on Tuesday and see what they need for info. and see if they will give me an estimate. I'll post back here Tuesday night.

Thanks for the info. <img src="http://forums.aaca.org/images/graemlins/laugh.gif" alt="" />

[Guest bdl38s]

If anything comes from these inquiries I'll definately sign up for a new set of gears.

Brian

[scott12180]

There is a company called "Gear Vendors" who makes planetary overdrive units for a wide variety of applications --- most of them modern stuff, but they do work for vintage and restoration applications, too. They specifically say that they have a unit that can be fitted into a torque tube. I have no idea of the cost. Of course, you need to give them a torque tube cadaver.

My opinion is that if you really want to drive your car, and especially in hilly counrty, an overdrve is the best option. It preserves the low end grunt of the standard gears yet with the flick of a switch gives you a fourth gear when you want to cruise on the highway.

I have a Mitchell overdrive unit in my 1926 Packard, and I wouldn't be without it. (Although I am not happy with the Mitchell.) I am planning to install a Gear Vendors on my 1932 Packard.

--Scott

[Only Buicks]

Ok everyone, here is what I found out. I had a nice conversation with the owner at ORF.

Bottom line is for one set of 3.615/1 gears (ring & pinion) he would charge $2,450.00 <img src="http://forums.aaca.org/images/graemlins/shocked.gif" alt="" /> For a multiple order of 4 or 5 sets he would charge us $1,800.00 per set.

He would need a set to work from, any ratio is fine he just needs them to reverse engineer. From that point it would take about 12 weeks to make them.

Let me know your thoughts on this. <img src="http://forums.aaca.org/images/graemlins/smile.gif" alt="" />

[Guest Straight eight]

I have a ring gear and pinion, brand new old stock, no wear, no pits, they show the part number stamped on them as 1336832 and 51-13 as the gear ratio. Can anybody use them?

[Only Buicks]

Straight Eight,

Do you know what this gear set fits?

[Guest Straight eight]

I do not know for sure. It was supposed to fit my 47 Super, but there was a complete range of years it fit because this is just a ring gear, and pinion. <img src="http://forums.aaca.org/images/graemlins/confused.gif" alt="" />

[jeff]

If Glenn is not interested, I might like to take a look.

Jeff

[Matt Harwood]

Straight eight, a 51-13 works out to a 3.90 gearset, which was the standard rear for the large series cars (at least in 1941-42). I guess the big question is whether the rear ends in the small and large series cars are interchangeable. Does anyone know for sure? I've seen The Old Guy talk about retrofitting his Super with gears from a later car, so I'm assuming that they are all the same. A 3.90 gear by itself might help the small series cars cruise better, but a 3.60, which was also available from the factory, would be ideal. I'm still trying to find a 3.60 set for my Century.

[Guest imported_JPIndusi]

The pumpkins on Buicks from 1940 to 1955 are interchangeable.

This means that if you have a complete pumpkin from a 53 to 55

with a 3.6 or 3.4 ratio you can bolt it into a 1940 and up,

but not 1956. You cannot take the ring and pinion from out of

a 55 pumpkin and get it to fit into a 4.45 pumpkin from say a 1948.

You must transplant the entire pumpkin. The reason is that the

later taller ratios have a larger diameter pinion that does not

clear the opening in the earlier case assembly. I am not sure

of the interchangeability of rear ends prior to 1940.

Joe, BCA 33493

[jeff]

Interesting footnote...

My Buick service manual mentions a "police package" for the Special that consisted of a higher compression cylinder head and the 3.9:1 ratio from the Century. (plus the speedo gear, I guess) If you discount the higher compression head (couldn't have been worth that much!), this indicates that the Special would run with the 3.9:1 ratio. The only difference will be more 3 - 2 downshifts when taking a turn - usually with the 4.4:1 ratio I can just motor through in high gear. This, I believe, is what people wanted in the days before automatics - less shifting. So, if you are ok with a few more downshifts in your life, I think the Special will run OK with the 3.9.

[Guest ZondaC12]

yes i saw that too in my shop manual!

hmm...higher compression cylinder head...yes indeed.

no just kidding as much as id like to i would NEVER put anything like that to increase power on my engine. 84000 miles, the things probably never been opened. i wanna see how long it will go. if it somehow works out that 20 years from now the engine runs as good as today, no blow-by, loss of compression, bearing wear, whatever, and it doesnt need rebuilding, guess what? it wont be rebuilt.

what a testament to this engine that will be!

[Fred Rawling]

Joe,

I was under the impression that 1940 to1954 ring and pinion gears were interchangeable in any of the rear ends from those years. You mention that 1955 is not interchangeable in your message. Are you referring to only 1955 or does that larger pinion being too big apply to other years?

[The Old Guy]

Zondac12

I have owned my 40 super since 1972,and did the engine in 1976. Since then I have driven it over 100,000 miles and have not done anything except normal maintenance. I had a 3.9 rear end in it until 1995 and then installed a 3.4. That made a whole new car out of it.

I also installed roadmaster brakes as it needed extra stopping ability.

[Guest bdl38s]

$1800 sounds pretty spendy for a set of gears. Is there any info on the cost of a possible overdrive unit ?

[Fred Rawling]

Joe Kreps made gears for the 29 to 35 cars and was selling them for around $800.00 a set. Look him up in the roster and see what information he can help you with.

[Guest imported_JPIndusi]

I said that the 1956 was not interchangeable. In addition, from my experience, the pumpkins with 4:45 ratios had a smaller diameter pinion and therefore the ring gear (and possibly the case) for this pinion was thicker so the pinion drive gear would be in the middle of the pumpkin. The easiest swap is to just replace the whole pumpkin into the rear end housing. Changing just the ring and pinion may require grinding off the rivets that hold the ring gear to the case. On these old Buicks I think they were all reiveted and not bolted.

Joe, BCA 33493

[Guest bdl38s]

Fred, I looked, but being a new member, I couldn't find any info on a membership roster for Joe Kreps. Where would I look ?

Brian Leinon

[Pontiac59]

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">The pumpkins on Buicks from 1940 to 1955 are interchangeable.

This means that if you have a complete pumpkin from a 53 to 55

with a 3.6 or 3.4 ratio you can bolt it into a 1940 and up,

but not 1956. You cannot take the ring and pinion from out of

a 55 pumpkin and get it to fit into a 4.45 pumpkin from say a 1948.

You must transplant the entire pumpkin. The reason is that the

later taller ratios have a larger diameter pinion that does not

clear the opening in the earlier case assembly. I am not sure

of the interchangeability of rear ends prior to 1940.

Joe, BCA 33493 </div></div>

I must have put up three posts asking this. Thanks for the info -

[theDBs]

hi there

overdrive spares in the uk make a possible overdrive unit that will fit but it isnt cheap at the moment at around £700

it is 15" long, 7" wide, 4.5" below centre line of prop & 3" above, this can be adapted to fit in the torque tube easy enough.

see www.odspares.com - conversions for view.

i would be interested in the new ratio at $1800 if we could decide on a spec (ie ring size which i think is 9.375" & ratio) & order as time is running out for me, (car has to be loaded in early May to go to Peking for Peking to Paris rally)

Chris

[Only Buicks]

Ok all,

I have myself and a gentlemen from the UK who is ready to press forward with a new set of gears. We need 2 or 3 more of you to come forward (if you are interested) in order to get the reduced price of $2,450.00 per set.

ANY TAKERS ???

Going once, going twice....... <img src="http://forums.aaca.org/images/graemlins/grin.gif" alt="" />