T5 transmission

[Robin7TFour]

Greetings, has anyone put a used T5 tranny in their Corvette? how much adapting to use one from a late 80's early 90's S-10 truck?

Robin

 

[MMM]

Robin,
I would not use a T-5 out of an S-10. The gearing stinks (second gear is nearly as low as first) and for the most part they are the non "World Class" type. The "World Class" model was a performance upgrade from the original T-5 design and used in high performance applications. I am very familiar with T-5's from S-10's having owned two Blazers with T-5's and rebuilding the transmissions in both vehicles. Use a T-5 from a Camaro or Firebird and make sure you use the World Class version.
Mike

 

[AdvancedAutoCC]

T5 trans

ANY T5 out of a production vehicle is a colossal waste of time and money..T5's are notoriously weak units that break with stock horsepower levels (from 4 to 8 cylinders). Your best bet is a Tremec transmission (5 or 6 speed). Tremec is the upgraded "World Class" version of the T5/T56, and is available in several versions.

Ask yourself this question: Does a transmission rated for a 4 or 6 cylinder engine belong behind ANY V8? I didn't think so...

Issues to consider include clutch linkage, driveshaft length, etc.... not for the faint of heart or mechanically challenged... Refer to the "Project Rule of Thumb" (hmmm..sounds like a good sticky!)

 

[Ripp 73]

Speaking about switching transmissions... What do people recommend for a 76? I've thought about putting in a rebuilt 700R4 or something along those lines. This would not be a project until spring but I guess now is as good as anytime to bring this up. Has anyone tried this? How much transforming is involved in this process? Thanks for any input.

 

[Pancho]

Hmmmmm. You ready for a little story?

When it came time to decide what to do with the turbo 350 trans in my '76 a few years ago, I decided I'd really like to switch to a manual. I did a lot of research, and while the T-5's had a bad reputation I decided if cared for and driven 'not too hard' it would make a good choice considering the availability, size, OD, etc. I bought all the parts to convert my auto to a manual (most parts purchased off EBay), and over the course of a summer I had it in. It was not a quick and easy job by any means, but most of that was because of the swap from auto to manual (regardless of manual tranny type). I had to cut a hole for the shifter in the tunnel (...somewhere along the way they closed up the hole in the tunnel on auto cars), weld in the bracket for the Z-bar support, you name it. I used a late-80's Camaro (world-class) T-5, rebuilt it just in case, used a mechanical clutch bellhousing from an '83 F-body (the only one with the tilted T-5 pattern that wasn't hydraulic), and shortened the driveshaft 3" or so. I fabricated a trans-mount (which happened to be pretty close to the stock one, just 'streched' a bit). The shifter (I used a Hurst Competition-Plus) poked through in just the right spot, and with some finagling of the dust/moisture boots, was even able to get the console plate (.... a 4-speed top plate) to fit.

It drove fine, the clutch was no problem, and life was good.... the only problem was I was always afraid I was going to break it. Maybe it was thinking about all the bad stories, but I found it hard to bring myself to push it very hard.

Last summer, I was looking for another project and..... I decided to swap the trans out for a 700R4 from BowTie overdrives. I 'undid' all the auto-to-manual swap parts (sold them all, including the T-5, on EBay and got 'most' of my money back....hey, I said this was a project, not an investment..... ), used BowTie's transmission crossmember, and everything slid right in. They sell a kit to modify the stock shifter which adds the extra detent for the 4-speed 700R4. The TV cable setup is a little picky, but is no problem with a pressure gauge. Bowtie Overdrives is also very particular about making sure the system is being cooled adequately before they warranty it, that's still something I'm working on (..... it's been 15+ years since I've had to do anything with the radiator, maybe now's a good time for an aluminim replacement....) The shortened driveshaft from the T-5 project fit with the 700R4.

The car drives great with the 700R4, the only exception being I find that in-town, I leave it in 3rd to keep the RPMs up enough or else it upshifts to 4th pretty early and I end up going 40 MPH just off idle..... playing with the system to delay 4th engagement also affects 1-2 and 2-3, which are where I want them for the moment.... so will play with the governor and/or TCC lockup circuit to at least prevent 4th (and TCC lockup) from occuring below a certain speed. For now leaving it in 3rd is no big issue until I get on the highway.

If I had it to do over again...... hmmmmmm.

Sorry for the drawn-out story..... if anyone wants more details let me know.

 

[Robin7TFour]

Robert, i was wondering about the S-10 T5 only because a Tremec is way out of my budget right now. i figured i could pick up a 'salvage yard' unit and then do the install myself. i see how wrong i was. hope i didn't look too stupid to you!

Pancho, i do enjoy hearing your story on how you swapped. do you miss not manually shifting you Corvette? i really would prefer a manual just for that reason. plus, the previous Teenager put a good cam and Crane roller rockers in,but no stall converter. so i have to idle (in neutral) at 1500. that's just to get a decent 700rpm in drive.
i may just do more reading to see what i can do to my TH400 to make it more interesting to drive..

Robin

 

[goingballistic]

Tremac is the way to go if you're gonna do it.

I rebuilt the T5 on my I wife's Stang last summer. My oldest son shattered 2nd gear and the third gear synchro. Direct replacments are available but hard to come by and NO ONE recommends using them. The reason is that the original design was ( if I remember) 24 tooth on second, they redesigned to 23 which meant the entire shaft had to be replaced to accomodate it. It was no big deal in this as the shaft was shot as well ( 3rd had a tooth missing). I upgraded everything and it runs strong but if I had to do it again, I wouldn't run the risk and would go directly for something else. They knew they had a problem and hence the reduction in tooth count ( stronger gearing) and moved to the tremac 6 speed.

In my humble opinion, I'd stay away from the T5 if possible and certainly wouldn't even entertain the idea of an S-10 T5. As was said, anything below a "WC" (world class) rating is a waste of time and money.

I also wouldn't be messin' with Ford stuff anyhow ...just kidding, I own 6 fords and a vette......actually seven including my Ford 2000 Diesel....

 

[AdvancedAutoCC]

Robin,

No worries, the only stupid question is the one you don't ask. That's one of the many reasons this forum exists. I've always believed in telling the truth about car building, etc, and not blow sunshine up anybody's skirt. There's enough misinformation out there already about the supposed "ease" of car building ("reality TV", anyone?), and I just try to keep things in perspective.

T5s are cheap for a reason...they're like Doritos - "Crunch all you want, we'll make more.." :L

From the sound of it, you'd probably be happier with a good converter and shift kit for your TH400 (which is pretty much bulletproof), and that would likely be your most cost effective option.

 

[MMM]

Does anybody make a Switch Pitch replacement converter for a TH400 these days? Used to be able to get them from Kenne-Bell when they were selling Buick high performance parts. They came standard with factory TH400's in Buicks, Olds, and I think Cads in '66 & '67. I installed one in an '80 Chevy pickup that had been converted from a 350 diesel to a 350 Olds gas. The owner went thru 4 TH350's and wanted something stronger. I rebuilt a switch pitch 400 out of a '67 Dynamic 88 and installed it. Wired the converter to operate as designed from the switch on the throttle linkage (combined with the kick-down switch) or from an override switch which locked it either in high slip or low slip. Worked great. Was a great high performance add on.

Mike

 

[Robin7TFour]

mike enlighten me... what's a switch pitch?

R

 

[bossvette]

there is a 70's GM truck trans that is a direct replacement for the 4 speed the only fabrication needed is the shift linkage. It is a 4-speed used in suburbans and pickups and 4th is overdrive; one of our local Corvette club members has had one behind a 454 for quite a while. a real low budget alternative.

 

[MMM]

Robin,
The "switch pitch" TH400 was built by GM for BOP and Cad use from '65 to '67. I understood the reason it was discontinued was economics only, it was just too expensive to manufacture. As a side note, the two-speed TH300 (also used in BOP cars) also used the switch pitch converter in the same years.
What is it? A torque converter with two stall speeds. A low slip with little torque multiplication and very little slip and high stall with increased torque multiplication and more slip. The angle of the stator blades in the converter was electrically controlled. When the converter switchs pitch, it feels like a gear change. Almost created a six speed transmission, but with no OD. The best you could do (for economy) was the low slip setting which was almost as efficient as a lock up converter. But for drag and street racing it was great. You could have a high stall converter for great launches then switch the pitch for top end. Kenne-Bell sold remanufactured converters with greater high-stall capability then stock. The off-roaders loved them because of the enhanced torque conversion and power application offered by the high-slip setting. In the stock installation the stator pitch was controlled by a micro-switch on the throttle linkage. But it could be easily overridden for manual control. One person I knew installed a manual switch on his '66 Buick Special SW. He swore it was the best snow vehicle he ever had. Just switched to high slip whenever it began to spin the wheels.
Mike

 

[norvalwilhelm]

After blowing 3 700R-4's in one summer I decide to go standard. As a test I started with a T5. While everyone says they are weak one has stood up for 15 hears behind my nitrous 355 89 mustang running slicks and carrying the front end on launch.
I DO NOT POWER SHIFT. 3rd gear is the weak gear and no amount of burnouts in first will break it.
Power shifting is the problem. Make fast positive shifts and it will live.
Anyway behind my blown big block one lived for a whole summer, I didn't care if I blew it or not , agian never power shifting but lots of burnouts even in 3rd.
I sold it at the end of the summer and installed a tremec for reliability.
I wouldn't hesitate to go to a T5 and the old 4 speed without an overdrive is out for me.
Yes I used the Ford T5 because they are cheap and plentiful while the camaro T5 cost $300 to $400 more and are hard to find.
The cases are almost the same, Some parts are interchangable , they are almost the same transmission with different mounting and input and output shafts.
So if it lived in my nitrous 355 mustang and my 460 blown vet it isn't that weak.
If I didn't want to spend the money on the tremec I would not hesitate to go T5
Same as already stated. NO to the S10 unit and the 6 cylinder T'5s while having a great low low 1st are a touch longer input shaft and push the thrust bearing too far forward as well as the pilot bearing being too small.
A good T5 from a V8 camaro will live IF you do not POWER shift.
A idiot with a nitrous 350 camaro who goes through 3 or 4 pairs of tires a year uses the 6 cylinder version and blows about 1 a year of those cheap T5's but every shift is a power shift.

 

[Robin7TFour]

Norval, thank you for the detailed analysis. i have seen the pictures of your car,and it looks powerful in the pictures.
i don't expect to do any powershift. i want a manual,because a Corvette deserves to be shifted when driven.
thank you ALL for the info. will definate spend more time asking questions.

Robin