The Stovebolt Site Forums The Shop Area Driveline 1946 1/2 ton higher top speed options

Sorry if this has been addressed before and I missed it. I have a mostly stock pickup (235 was added by previous owner) and I’d sure like a bit higher top speed.
Anyone have any experience here? It has 410 gears and maybe a different ratio is available? I’ve read a bit about a S10 5 speed swap but I’m not sure that’s my answer. Overdrive available? Two speed rear end? I just don’t know what’s out there.
Thanks in advance for any input.

What's your top speed now? What do you want your top speed to be in a 77 year old truck?

I drive a 1950 3100, 216 3spd with 4.11:1 rear end. It has stock 16" wheels with correct sized tires. It tops out at 65 but I drive it 55 - 60mph a couple hundred miles every week. That seems fine to me for a 73 year old truck.

Otto I’ve owned this truck for just a month now. I’ve had it up to 50 and it just needs another gear in my opinion. 60-65 would be great. I understand what you’re saying. It’s just a question in case it’s an available option somehow. My 37 Pontiac is even slower. Still looking for options in that one too. Thanks for your reply.

Going faster is fine- - - -as long as stopping and steering get a corresponding improvement. How big a hurry are you in to get to your funeral?
Jerry

You say you've had it up to 50. Does that mean it will go faster but you're afraid to push it? You won't hurt it. See what it will do. With a 235 you ought to get up to 60 pretty easily.

I assume you have stock diameter tires. If someone put dinky 15" fat tires on it, install 16" wheels and 225x85x16 tires. Larger diameter tires will give you higher top speed at lower rpm than smaller diameter tires.

The S10 5 speed (also known as a T5 transmission) IS overdrive in 5th gear. Ratios vary between 0.86 and 0.72 depending on year.

A 0.72 OD would get you to 69 MPH at the same engine speed you are currently running 50 MPH IF your 235 could get back to that RPM with the higher speed gearing and IF you had the intestinal fortitude to drive it that fast.

Yep, stock 16’s and skinny rubber. Admittedly I haven’t taken it over 50 just because… I really love driving it and don’t want to mess anything up. Thanks Otto. I’ll feed it the onions and see what we get.

Bill I’m sensing from and another fellow that I should not drive my stock truck any faster than maybe 55? It stops great. No worries there. I suppose that it may not handle “evasive “ maneuvers all that well with the stock little tires. Can’t blame me for asking and just wanting to putt along a little faster.

Bob: Not at all. On highway trips I typically drive my '52 GMC 3/4 ton around 63-65 MPH. I've had it to 75 (with a tailwind). It has the original 228 GMC engine. Updates include a 3.55:1 rear gear and disk brakes. Engine specs say max HP is at 3400 RPM. If I could get it spinning that fast it would go 83 MPH. I'm not THAT stupid.

I don't know your tire diameter, but if it were 29" at your current 50MPH top speed you would only be turning the 235 to just under 2400 RPM. 60 MPH would be 2858 RPM.

If you install larger tires, you will not know any difference on the speedometer unless you change speedo gears, so find some mileposts 10 miles apart to determine your true speed. Then remember which percentage your speedo is off, keep it in your memory. Other speedo gears may not be available.

Ed

Are the tires on your truck radials or bias ply?

If they're radials, don't worry about the skinniness and handling. I don't put modern fat tires on anything and the skinny radials on my cars handle perfectly fine - much better than skinny bias ply tires.

Anything you do to get more speed and or slow the engine RPM's down is going to require a gear change of some sort.
T-5's and other overdrive units are going to require a change to an open driveline. Since you have a later engine with the stock
driveline, a later bellhousing will probably be needed as the trans mounting pattern is different. So add up the changes,
rear end assembly (6 lug to match the front), modified rear springs, bellhousing, transmission, driveshaft, and possibly mounts.
In my opinion any vehicle with a gear ratio in the 3:90 to 4:10 range needs something higher for better drive ability
but how to get there can be time consuming and costly.
Fred

The last three 4x4 GM trucks that I used for daily drivers all had 4.10 axles, these were 3/4 or 1 tons and were not available with a higher gear. I would prefer a 3.73 but that was not an option on the 4x4's. My 1976 K20 with a 350 and SM465 had no problem on the highway, the other 2 trucks had/have overdrive. My current 2011 2500HD 4x4 with the 6.0 gas motor could easily pull a 3.73 axle, I would opt for that in a heartbeat if it was available. I'm in the slow process of acquiring a 2 speed pig for my '57 2 ton and it should be a good addition, currently the rear is a single speed 7.20:1, the 2 speed will have a higher high and a lower low. I'm not expecting to ever take this truck on the interstate but it might do 55-60 against the governor.

I have bias ply tires Otto.

Thanks Fred. I believe you’re right. In my mind the simplest is a rear gear change but I can’t find any info on the availability of taller rear gears for my differential.

I won't totally knock bias ply tires. I drove with bias plies on my '56 Cadillac for the first 7-10 years I owned it. I found them to be comfortable and decent handling due to the stiff sidewall. I regularly drove thousands of miles at modern highway speeds with them. Of course the Cadillac weighs 5000 pounds verses a truck like yours that weighs a little over 3000 lbs. I think that has a lot to do with how well the car stuck to the road.

When I switched to radials, however, it was a night and day difference. The car never rode and handled so well as it does with the Diamondback radials I installed. If you're going to be doing a lot of "high speed" driving, I strongly recommend installing them. They are made to look like bias ply tires but have all the advantages of radials.

Both my Cadillac and Packard have them. They are far superior to those offered by Coker Tire.

If you want a wide whitewall, these tires look great and don't have that fat radial tire bulge that looks ridiculous on 70 year old vehicles.

https://dbtires.com/product/auburn-deluxe-radial-15-16-sizes/

www.dbtires.com

What gear ratio 2-speed have you found for your '57 ?

Mike B

Hey Mike, my hope is that it will have the 8.72/6.40 ratios that the GM Heritage specs call out. The doner is a '56 6000 series Chevrolet with the corporate rear end, vacuum shift. I have measured and compared the bolt pattern on the pig and it is the same as mine so I'm hoping it will be plug-n-play. We have been waiting for the weather to cooperate so I can power wash the axle housing and pig before I remove it, I want to keep it as clean as possible so no grit gets into either unit. I'll take one of my axle shafts and compare it to the doner, if that matches then I'll move forward with removing the doner pig.

On the topic of steering, here is a tip: if your steering and drag link balls are worn egg-shaped even a little bit (and if they're original they certainly will be), replace them and use the type of balls that are threaded so as to fasten with a nut. Why use these instead of the welded in type? So you can rotate them 90 degrees a couple of times each year. That will prevent them from wearing in the same spots and becoming egg-shaped. Those balls are pretty soft steel and in a few years you'll be glad you did this. Also check the machined cups. They wear out also even though they're harder steel than the balls. I've seen some of these pickups with more than 1/4 inch of slop in the steering and at 60 mph that is exponentially more dangerous than driving around in the neighborhood. Oh, and also...please follow the shop manual when re-assembling your drag link. Once you have all the stuff out to clean/rebuild it, you may not recall the assembly order (which is important). The sequence is: Steering gear end: first goes the spring, followed by the stepped spring cap followed by the two ball seats followed by the end plug. Control arm end (it is DIFFERENT): first the two ball seats followed by the stepped spring cap followed by the spring followed by the end plug. I'd spend the money on the new style tie rod ends. Years ago you could buy the parts to make an adjustable drag link but at least one of those parts hasn't been made in over 10 years. Even if they were available, the original drag link is better. I made one of these adjustable drag links (using all the right parts) and it lasted exactly 3 years before it developed too much wobble and consequently end play in it. When you adjust the drag link, tighten the end plug all the way using a large screwdriver or flat socket bit. Then back off 1 turn plus any amount needed to locate the cotter pin hole. I've even erred on the conservative side and screwed the end plug back in a bit if the cotter pin hole was very close to 1 turn out. I attached a couple of images of used cups to this post. In the one with 3 cups you can see one is ok, the edge of one is worn almost sharp (like the edge of a knife) and one has a cracked edge. One can be re-used, two need replacing. In the second image you see a close up of the two bad ones. Good luck!

Axle housings should be the same...if you want to discuss further, start a new thread so we don't hijack this one.

Mike B

10-4

When inspecting axle shafts for two speed rears, some two speeds have equal length axles and some single speed axles have different length axles.

Ed