The Stovebolt Site Forums The Shop Area The HiPo Shop driveline and gearing ?

Hello all, I'm picking up a stock 1954 3100, 235 4 speed sm420. I'm looking for any advice or words of thought on the vehicle and the driveline setup..

I plan to drop it with a 4" beam from Sids and a combo of blocks and spring for the rear.. I will be adding front discs and a dual master. I'm still on the fence on whether to go 5 lug or keep the 6 lug..

I'd be running a 27 to 29" rear tire depending on the rear gear ratios.. not really looking to run a V8 , I do want to tool around town and occasional highway driving 20 - 30 miles max..


My first question what is the spring pad width center to center pin ? I know the max width wsm should be 60-62" I'm trying to find in a bolt in solution for the rear axle.



I know the engine is not running, but it turns free. The vehicle is not in my possession yet.. That engine may be a runner,but I don't know.. Can I use a 12v battery to do compression checks and try to get it running? before I convert it from 6v

I'm in the north east with a lot of hills locally. I've had 3 speeds and I6's before and they are not fun in my local area. In my youth I'd just swap in a V8 and make up for the lack of gearing but it would loose some of the fun factor in one way but gain in the other...this is why I want to swap in the saginaw 4spd or t5

from least to most work..

option #1; get the unknown 235 up and running.. ( I would have trust issues with this option) adding hei, cast header and maybe a bigger carb or cam

I have a 4 speed saginaw 2 line here to toss on the rear of it..

2a swap rear to open drive line gears? 3.50?
2b swap in 3.32 gears and keep torque tube.
2c swap in t5 from s10 I'm not made of money so I'll prob have the crappy 4cyl gear set and open rear with 3.75 or 4.10



option #2; I can get a 1958 235 with low miles in running condition of $400 out of a truck.. (would add headers hei, cam ect..)

I have a 4 speed saginaw 2 line here to toss on the rear of it..

2a swap rear to open drive line gears? 3.50?
2b swap in 3.32 gears and keep torque tube.
2c swap in t5 from s10 I'm not made of money so I'll prob have the crappy 4cyl gear set and open rear with 3.75 or 4.10


option #3 I have on a stand a 60k mile running 250 (would add headers cam hei ect..) I have a V8 bell housing here

I have a 4 speed saginaw 2 line here to toss on the rear of it..

3a swap rear to open drive line gears? 3.50?
3b swap in 3.32 gears and keep torque tube.
3c swap in t5 from s10 I'm not made of money so I'll prob have the crappy 4cyl gear set and open rear with 3.75 or 4.10


option #4 I can pick up a rebuilt 292 with 4bbl and th400 for $800 then swap rear to open drive line gears? 3.50? not sure if the 292 is worth the extra work to fit with offset mounts or electric fuel pump..



My next question running the numbers is a cruising speed of 2800 (3.75 with 29" tires) OK for the 235 or 250/292 I do live in hilly PA. I thought about going with 3.08 and 27" tires which lowers the rpm for the high gears..2500rpm @ 65

I guess the question should be where in the RPM range do I want the 235 vs 250/292?

I'm reluctant to grab a t5 as most with mechanical speedo are running $500!! and that's with the low first and high OD. If I set my max rpm and mph to that trans the first gear is almost useless .. so why bother it's only a 4 speed and I have one here... I seem to be finding a lot of 3.08's and 3.75 not much in between that will bolt in..

If you keep the original axle, torque tube, I believe 3.55 is as fast as you can get?
If you keep axle housing and swap center section, open drive line, what ratio choices do you have? 3.73 I'm pretty sure, and 4.10, but anything faster?
You speak of 3.08 and 3.32 ratios, but what rear axle would you get those in, a Ford 9"?

I believe to help narrow your choices you can weed out the impossible ones, and the expensive ones if budget is a contributing factor.

This is a nice gear calculator
http://www.onlineconversion.com/bigger_tires.htm

In my experience with the old Stovebolts 2500 or there about is a comfortable RPM on the road, and they will do more but not as fun on long trips at higher RPM.

First though, just get running and driving with what you have (or another 235 or 261, easy swap) and drive it for a good while, perhaps years.
Then you'll better know and understand what changes you desire based on actually driving the truck, not guesstimating and hearing different versions of what works for different people in different situations.

Grigg

I agree, get it running and get some road miles on it. As far as 250's go, mine likes 2300-2500 on the road. Thats 65 to 70 mph with a 3.08 gear and 28" tires. It pulls just fine off idle and around town. I had a 3.55 for awhile, it was much quicker from a dead stop, but highway speeds were terrible.

In my '50 3100, I put a completely rebuilt high pressure 235, a T-5 out of an S10 which had a 4 cylinder in it. I have a 4.64 limited slip rear end out of a Nissan Xterra. 28 inch tires.
1st gear is nearly a granny gear. 65 MPH is the max I am comfortable with. I need to get some 31 inch tires to make 1st gear more usable and lower the RPM in 5th gear. All and all, I am very pleased with what I have.
A 3.73 rear end would probably be the ultimate choice for this application, but I could not find one at the time.
I would stay away from a 3.08 rear end with a 3 speed transmission. The 235 does not have enough power to get out of its own way with 1st gear being too high. A four speed with granny gear would probably work with the 3.08 out of the hole and at highway speed.

Thanks all, I will try to get the 235 I have in it going for sure and either way if that one works or not I may pick up the spare. If I decide to stay with the engine setup..

Unless I can be convinced to keep the torque tube setup I will be changing the rear. I see I can use my saginaw 4 speed with the TT with a conversion kit. The area I live is filled with hills and the last 5 vehicles I've had with 3 speeds were terrible and not fun to drive. I either swapped motors or trans to make for something I wanted to drive..

I found a nova rear in 3.08 or I have a truck rear in 3.75 or I'll just keep looking for the "right " gear ratio in an early FB/camaro as I'm leaning to the 5 lug setup..

I know this is all a bit fluid right now. I just have time, I love the hunt and if I can get a direction I'll go with it.. Great info on the RPM range for both motors at lease I know a sweet spot..

I just don't want to toss money into the 235 only to desire the 250 or 292 later on .

The Firebird / Camaro rear axle from '71-'79 use the 8.5" ring and pinion in the 10 bolts. GM used the same ring and pinion size up through the '90s so finding a different gear ratio is pretty easy once you determine which cars and trucks used them. There is a difference in the u-joint size, but nothing to hard to over come.

Well I picked up a 1988 S10 T5 with mechanical speedometer drive it was local and under market value... It's the 3.76 first and .72 OD . not ideal but should work. I'm searching now for either a bolt in 3.73 or 4.10 camaro/ nova rear or if I found a 55 - 64 center section in the 3.90 range I'd keep the 6 lug setup and use my rear.. not finding anything local...


I still need to decide to keep the 235 , foot starter, vintage look and convert to 12 v or go with the hot rod 250 .. I have the bell housing , I'd just need to add new motor mounts. This would make easy AC down the road and off the shelf parts and more power...