How to get lower axle ratio on 1937 40 series

[sleeve-valve]

My friend has a 1937 40 series and would like to be able to drive at highway speeds with less rpms. We can't find aftermarket ring and pinion, and am not sure about fitting an overdrive unit with the torque tube. What options are there to lower the rear axle ratio? Thanks.

[jeff]

I'd like to find a solution for my '38.

Best fix, find a ring and pinion for a 60 series. Good luck, they are pretty scarce.

Second best, find an entire rear - some guys on the forum made some recommendations for post war axles recently, but I think they implied that the post war choices only would retrofit to a '40 or later.

Maybe someone can clarify.

[Guest ZondaC12]

Yeah I think presently the only option is to go the way member "38Buick" went (at least I think???) he found someone to custom make a ring and pinion. I think it was real expensive, as in like $2k or something but kinda neat that someones makin em!

[Dave_B]

Lloyd Young of Canal Winchester, Ohio can install a Borg Warner overdrive in cars with torque tubes. He does nice work and you get about 30% reduction in high gear. I put one of his units in my '28 and I just love it. 55 mph is now a comfortable speed. In your case I'll bet 65 would be easy all day long. Plus you are not holding up traffic when the light turns green, cause you still have that low first gear. I sent him the third member via UPS, he spliced in the overdrive unit and sent it back. I don't know what he charges now but it was about $1300 when he did mine last year. Very reasonable, I thought. His ph# is 614-837-7832. It might be worth looking into. Oh yeah and one more thing, with one these guys in the car you don't have to pull the rear to change the clutch. Now ain't that great!

Dave

[Guest bdl38s]

Dave,

An O.D. unit looks like it would be the way to go. I have a 38 coupe that could stand to have a lower rpm at cruise. Looks like you shorted us on Lloyds phone number though. Cough up the last digit.

[Dave_B]

Oops, sorry. I edited my last entry with the whole number. But just to be sure the number is 614-837-7832.

[Only Buicks]

Hi,

As Zonda recalls I did in fact have a new ring & pinion made for my 38 along with one other guy. Zonda is also correct on the money end of it, not cheap. I ended up selling the car before swaping it out as it was going to be my winter project. I am not sure how the other buyer made out with his set. My original ratio was 4.4/1 the new set is 3.6/1 which should have made a very nice change. If your interested in the set let me know, I'll let it go at a decent price. If I had known about the OD units I probably would have taken that route.

[Guest ZondaC12]

Wow I dont know why I somehow missed the price of that overdrive...thats amazing. Still not an option for me but nonetheless thats far less than I would have imagined. Im thinking thats the route I'll go...someday haha. One particular thing I like about it is it would turn a 3 speed car into a 6 speed car if used the right way in addition to helping with the rpms on the highway.

[Guest imported_Thriller]

If interested, there is a '41 rear end on eBay...it is the 3.9 ratio. I can't be absolutely sure, but from what I've seen on the forum, I believe it should fit.

[Guest bdl38s]

I just talked to Lloyd Young and he certainly does install an OD in the 38 buicks. $1375 is the price. You take out the drive shaft and housing and ring and pinion gears and he'll send it back with the OD unit. Now all I have to figure out is how to take out the parts he wants. I'll most likely find someone who knows what he's doing.

Brian

[Guest imported_JPIndusi]

The complete pumpkin from 1940 to 1955 are all able to be bolted in to the rear end housing for these same years.

For the earlier years, as the other posts suggest, one can get an overdrive unit installed or find another pumpkin from another model such as a Century or Roadmaster, or find a complete post war rear end assembly and fit it to the springs and rear suspension. In the case of my 1948 Series 40, the pumpkin was replaced with a 3.40 to 1 and we used my original drive shaft and torque tube.

Good luck.

Joe, BCA 33493

[Dave_B]

Brian, All those parts come out as a single unit, from the back of the universal joint to the rear. You have to pull the axels to get the third member out with the ring and pinion still in place. When you get it back Lloyd will have set up the ring and pinion so no adjustment is needed. Just do it all in reverse. Yer gonna love it. When you get up on the interstate and drop that baby into overdrive and listen to that big straight eight hummin' along at 65 mph. Oh Yeah

Dave

[Guest ZondaC12]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: JPIndusi</div><div class="ubbcode-body">The complete pumpkin from 1940 to 1955 are all able to be bolted in to the rear end housing for these same years.

For the earlier years, as the other posts suggest, one can get an overdrive unit installed or find another pumpkin from another model such as a Century or Roadmaster, or find a complete post war rear end assembly and fit it to the springs and rear suspension. In the case of my 1948 Series 40, the pumpkin was replaced with a 3.40 to 1 and we used my original drive shaft and torque tube.

Good luck.

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

With a 3.4:1 gear, how is your acceleration? Is the torque of even the small 248 engine enough to make the tradeoff not too painful? Granted these don't accelerate like modern traffic anyway but I do alright if I let her wind up a little in first and second, maybe to almost 3k rpm each, and she has good torque in both. Easing on up to no more than 1/3, MAYBE 1/2 pedal, 30 even 40 mph ccmes up in well under 10 seconds, and the engine doesn't seem overburdened.

Also, one thing I thought of just recently. With an overdrive OR new gears out back, what happens to the speedometer? Won't that be thrown way off, as well as the odometer and trip?

[Guest imported_JPIndusi]

The 3.40 in the 48 Special seems to run OK. First gear and reverse don't seem to be affected much, plenty of torque to get going. Second seems a little flat sometimes in local traffic. High gear is great for going down the road. I would have preferred a 3.6 but I was shipped a 3.36, so that is what I had swapped the 4.45 for. It makes a good driver and allows me to keep up with the other cars without straining the engine. Not a good parade car though, with the old rear end I could let the clutch out at idle in first and walk next to it.

Yes, the speedometer is off, but I mark the 55 mph spot with a small piece of tape. There are gears available to convert but I don't feel its worth the money.

Joe, BCA 33493

[Dave_B]

Yes the speedo is off when in overdrive. It is off by a percentage so you can do the math, you can refer to a convertion table stuck to the dash or.... you can get a cable made up to connect the speedo to the od unit. There are also devices to correct for the various gears involved. I am looking into connecting the speedo to the od mostly because I want the odometer reading to stay true. But then it is a good thing to know how fast yer going too.

Dave