The Stovebolt Site Forums The Shop Area Driveline T5 upgrade

Will a T5 tranny ( 1990 S10 Borg Warner with gear ratios :1st 3.76, 2nd 2.18, 3rd 1.42, 4th 1.0, 5 th .72) paired with an Easton HO Rear end From a 1958 1/2 PU (probably a 3.90 rear) be a good combo to get me down the highway at 55 to 60 mph? After researching I know The speedo cable will require a converter, will need to modify the rear end including an open drive shaft and switch out the third member utilizing my current axles. I have the Tranny and am looking at purchasing the rear end.

Thanks for any input.

What engine and tires size do you have?

Pretty much any of these trucks will do 55-60 all day long in their stock form. Is there a specific concern you have about yours that you think you need a change?

Note: I have no issues with the T5 swap, it can be great. I just want to make it will help with the problem you are trying to solve.

Current engine is a 235 with hydraulic lifters from a 52 passenger car. I have a spare 235 from a 62 truck that I plan to swap in when I convert the tranny Tires are 235-85-16
The original 420 4 speed with a 411 rear end will do 50 mph but really is wound up in 4th gear.

Using this calculator and figuring your tires are 31" tall, your babying your engine. At 3000 rpm (way below the 4000 rpm limit) you should be in the 69 mph range. These engines were made to run all day long at 3000+ rpm.

https://spicerparts.com/calculators/transmission-ratio-rpm-calculator

Mike B

Yes.

But your stock combination should easily be capable of 60. I used to cruise my 216 close to 60 on the highway at 2700-2800 rpm, 3 speed and 4.11, no problems at all, just noisy. A tach really helps put into perspective how wound up it sounds versus how wound up it actually is. That, or the gear ratio calculator.

I have had a T5 in it for several years and it's nice. Attached is a snapshot of my current highway cruising conditions. Stock 216 in a 50 half ton with a Task Force rear center section.

An 0.72 5th gear with a 3.9 is going to be a rough combo for a 235.

Lugnutz has a good analysis of recommended ratio combinations for different engines, but the short version is that will struggle.

As others have said, you can wind that engine up to 60MPH all day long with no issues. The fan is the greatest majority of the noise at higher RPM.

Going to the 3.9 with the stock transmission would give you a bit of a boost without being a huge job.

.72 overdrive with a 3.90 rear gear ratio and 28" high tires would be a good combination.
I have a '50 3100 with a 4.64 rear gear ratio, but had to go with 30.5" tires to dial it in.
I can pull stumps in first gear and drag it down the road at 65 MPH. Any faster than that and the stump tends to bounce around too much to be considered safe by many.

Hi Swami,
I have a 3.07 rear end, a .86 fifth gear and 27 inch diameter tires and it works great. Nice, quiet and efficient. At 65 I'm around 2100 rpm and the engine is just humming. If you're using a 235 made between 1959 and the end of production in 1962, you get a bonus. You get the camshaft that produced maximum torque at the lowest rpm...that being 217 at 2000 rpm. The 1958 235 required 20% more rpm to hit max torque which was only 215. And if you look at the torque curve for 1959-1962 you'll see it is a nice flat line starting around 1600 rpm going all the way over to 2500 rpm before it starts the decline. That's an impressive line, by the way.

Here is something for you to consider: When your truck was made the engineers wanted it to have an overall first gear ratio of 12.08. That's 4.11 x 2.94 (your stock 3 speed first gear ratio) and they knew what they were doing...it works well for the engine power to weight and ratios like that were used in almost all 1/2 ton pickups. That overall ratio will let you put 1000 pounds of stuff in the bed and drive around without burning out your clutch. It will also let you travel through a city intersection without having to shift to second. If you use a 3.90 rear end and a 3.76 first gear ratio you'll have an overall first gear ratio of 14.66. That's over 20% higher and what that extra ratio means is you'll be needing to shift from first to second sooner than you might enjoy, second to third a little sooner and on and on. Not a condemnation but just something for you to think about before you pull the trigger. The stock overall ratios were 12.08 (first gear), 6.90 (second gear) and 4.11 (third gear). Your ratios will be 14.66 (first), 8.50 (second), 5.54 (third), 3.90 (fourth) and 2.80 (fifth). First and second gears are where I think you may not enjoy that ratio chain as much. May not be a concern in Prineville but in a city like Dallas, that much shifting all the time can get old and I think you might be looking for something that would let your engine wind out more slowly and have you shifting less frequently. Good luck no matter what you choose!

Great info guys. I think it`s best to continue studying my options prior to making a choice about the tranny and rear end. This truck has been a great work horse over the years hauling firewood, gravel and yard debris. Every time I drive it I think "I should spend more time in it rather than my other vehicles" but for longer trips I choose the more modern vehicles, quieter, smoother, etc. Probably should just accept it for what it is and what it was designed for! Half the fun for me is spending the time in the shop tinkering with this or that, learning mechanics in my golden years. Believe me, I have plenty of other jobs to tackle on `Ol Buzz` so you will probably continue finding me lurking around the forums. Cheers....

The number one benefit of the T-5 is the availability of two more shifts in the mix. No more lugging, then screaming, then more lugging and more screaming. Every time you shift gears with a T-5, you will be at the optimal power band of the 235 engine.
It is by far the best way to get all of the performance that you can get from a Stovebolt engine, and as a bonus, it's easier on the engine, not to mention comfortable, real highway speed in fifth gear.

What Carl said.

I gotta find me one of those T5's. Or the TKX.

If by chance you talk yourself into getting a T5 . . . .
A 235ci will like the 0.86 fifth gear better than 0.72 (assuming you drive it where hills exist).
Don’t even THINK of using one with a 0.63 fifth gear.

A T5 can be converted to cable speedo output. You’d need the repop S10 tail housing and a correct length shift rail if by chance the T5 shift rail isn’t correct already.

Stay away from the Ford Mustang T5. The 1994-95 S10 has a Ford bolt pattern but an adapter plate can be used to get it to bolt to almost any GM bell.

Overall, a T5 might be a “long run for a short gain” so consider your options carefully.

Mine is out of and Chevy S10. The axle is out of a 1979 Nova and I was told 2.73 gears.

T5 differences explained IN THIS VIDEO.