T5 advice

[V8COOPMAN]

Originally Posted by KJ714

So I’ve read the T5 threads, I’m looking to have one built.

It sounds like to me I want a WC pre 93 S10 Chevy bolt pattern 14 spline input 26 spline output 3.76 mechanical speedo box to go behind a 36 flattie using a speedway conversion kit. Is this right? Or did I get something wrong? There’s so much info out there it gets kinda confusing reading through it.

Edit - since I’m having it built, what would be the best 1st gear? Not looking to do burnouts, 21 stud driveability is key.

You're right, there are truckloads of information available about T5s on the internet and not all of it is necessarily accurate info, and there is also misleading info out there.

One of the most-misunderstood aspects of T5 in these old cars is the idea of the need to use an "S-10" T5. Way back when, someone realized that the shifter on an "S-10" T5 was quite a few inches forward of most other T5 shifters. That's a great discovery as it makes it possible to have the shifter located quite a bit forward of a bench seat, or at least in a comfortable spot of the floor in your project car. BUT ..... "S-10" T5 transmissions all came out of little, wimpy 4-cylinder or V6 pick-ups that had very little grunt. For that reason, the GM folks stipulated that they wanted what was essentially a "GRANDMA" first gear of either a 4.03 or 3.76 ratio so that the things had a chance of reasonable acceleration when taking off from a stop light. You should realize that most old Ford V8 3-speed transmissions with a 28-tooth cluster gear had a 2.82 1st gear ratio, and that when you take off from a stop light in 1st gear, the speed and acceleration realized seems abundantly normal. If you use an "S-10" trans as-is in your project, you will more than likely find 1st gear to be almost useless in everyday driving. Gears and gear ratios in these old cars can make or break a project when swapping major parts like this. Planning and understanding of gear ratios and tire diameters should be of paramount importance.

The best of both worlds can be had with this T5 basic design. The Borg-Warner engineers made it almost TOO easy with this T5. It is such a forgiving basic transmission as far as swapping factory parts to come-up with different configurations. B-W T5s were originally built with only TWO different main cases ..... one with a GM bolt pattern like a Muncie has, and the other with the later Ford pattern like seen in a billion Mustangs. They are BOTH 9-1/4" front to rear. Both will readily accept ANY T5 gearset internally. This means that the "S-10" parts will readily bolt to the rear of any T5 case to locate that shifter right where you want it, yet with the option to use a gearset that is user-friendly for almost any kind of driving you have in mind.

If you're going to have one of the T5 rebuilding services to BUILD a transmission for you, you're way ahead of the game. Those guys have all of the parts available to them to build your "DREAM Trans". I just worked with another FordBarner that had a "DREAM" trans built by a rebuilder in Vancouver. He had a GM case mated with an "S-10" tail shaft housing and shift rod. He had them use an S-10 main shaft so that the speedometer gear located in the correct position with relation to the speedo hole on the tail shaft housing. Most importantly, he had the rebuilder use a "close ratio" gearset out of a V8 Camaro which has a 26-spline input shaft and a 2.95 1st gear. That 2.95 is only slightly higher numerically than that 2.82 Ford gear that we all use for 1st gear take-offs. Not only that, but the rebuilder happened to have on hand the relatively rare pair of 5th gear O/D gears to give him a .76 O/D ratio rather than the usual .63 O/D with that close ratio gearset. One more thing many don't realize about the 1st gear ratios we're talking about. The 1st gear ratio in any transmission is going to determine the overall torque rating of the transmission. Those T5s with 4.03 & 3.76 1st gears have a much lower torque rating than the 2.95 1st gear boxes.

Don't be afraid of a NWC (Non World Class) T5 as the only real difference between WC and NWC is the bearing type used to support the cluster gear as well as the type of friction material used on the synchronizers. NOTHING wrong with NWC T5s.

And going by your original post, I know of no "26-spline" output shaft. GM output shafts are 27-spline and Ford shafts are 28-spline. Hoping this helps you make an educated choice.

Coop


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