The Stovebolt Site Forums The Shop Area Driveline T-5's Question

Is the GM T-5 transmission out of an S-10 have the proven strength to handle a reasonable built GMC 270? I have a few different flavors of T-5's, Astro from a 4.3, Camaro from a 4.3, Camaro from a 5.7 and several S-10's. I have not thought of using one on an older pick-up but am now considering a future project. Your thoughts please...
Al
PS: NO FORD T-5's!

Lugnutz, You pose a very valid question regarding the ft-lb and HP of a 270. I am not sure, but I would guess a good target would be 125 to 150 HP? I have run more than a few of the T-5's and do like that they shift nicely though may not be the strongest.
Al

The higher rated boxes have closer ratio gears with 1st., etc., being higher.

Ed

HMMMM....I thought all T-5's have a wide jump between 1st and 2nd.

Hello Lugnutz, The potential project would be based on a 1946 Chev. 1/2 ton pickup (not good or complete or I would restore it). I have a rebuilt IHC 239 CID, 65 hp Diesel that I have contemplated using as the power and couple an S-10 or Astro T-5 to it. I would end up building a bell housing and of course doing all of the other adaptions. This project is down the list to about number 10, so it will not get any attention for a while.

The S-10 trans. have wide ratios but the V-8 Cameros are close ratio.

I have owned many different T5s so what I say is first hand knowledge from opening and inspecting them.

V8 Camaro/Firebird T5
1st gear = 2.95
2nd gear = 1.94
3rd gear = 1.34
4th gear = 1.00
5th gear = 0.72 (but 0.63 is more common)

V6 Camaro/Firebird T5 (these come in several versions but the most common is
1st gear = 3.758
2nd gear = 2.275
3rd gear = 1.42
4th gear = 1.0
5th gear = 0.72

A less common V6 Camaro/firebird version is
1st gear = 4.03
2nd gear = 2.37
3rd gear = 1.49
4th gear = 1.0
5th gear = 0.76

T5 from a V6 S10 or GMC Sonoma (this is the common gearing but not absolute)
1st gear = 3.758
2nd gear = 2.275
3rd gear = 1.42
4th gear = 1.0
5th gear = 0.72

T5 from a 4 cylinder Astro van
1st gear = 4.03
2nd gear = 2.37
3rd gear = 1.49
4th gear = 1.0
5th gear = 0.72

I want to make sure my thinking is straight. You have written the transmission gear ratios as a decimal per Astro:
1st gear 4.03 to 1
2nd gear 2.73 to 1
3rd gear 1.49 to 1
4th gear 1.00 to 1
5th gear 0.72 to 1
Does that mean in 5th gear that the out put of the transmission will see about a 25% over drive over 1 to 1 (direct drive) of fourth gear? I get confused with the gear ratio and what it means.
I bought new, in 1986, and special ordered a 4.3 Astro with a T-5. After many miles, a transmission reb. and my teenage son rolling/totaling it, I bought back the salvage just to keep the T-5. This transmission I still have stored, with only a few miles on it! I junked the rest of the Van for at least double what the salvage was and still was able to keep the T-5!

Ok, I scanned over your T-5 pages. Thanks for sharing your information. I will be using some of your ideas as I build my several transmissions.

Im using tag 145 right now. Thinking about changing to tag 148 or 149.

This is a good link for tags and ratios.

T5 info

Or possibly a 179 would be nice.

This question is for you lugnutz. I can see where the GM derivatives of the T-5 are compatible. Does much interchange between the WC and typical T-5? My last question, how about the internal parts interchangeability between Ford and GM derivatives? One last thought, the bell housing bolt pattern on the T-5, that came off my 1986 4.3 Astro, must be a Ford Pattern. Was that a typical trick GM pulled in those days? I kept the Bell housing so I could use the trans. in the future on a Chev. project.
Al

Has anyone put a T-5 behind a 350? I have a '55 with 350 with a 4 speed leading into a rear end (4:11 ratio)out of the same Camaro. It really turns many rpm at road speed. I would like to know if the T5 will stand up to the 350 for cruises and highway driving; no racing!

I have a s-10 NWC T-5 in my 56 with a 350. It works great. I don't race it or do burnouts or such but I'm not afraid to get on it occasionaly. I have the 3:38 gears in the original rear end.

My 2 cents....it all depends on the driver. I have two T5 vehicles, one is my stock (ish) 51 3600 driver. It's running a 93 WC T5 from a S10, it's a great tranny that I doubt I could destroy with my 85 hp engine on a dare. The other's in my Guy toy...a 1990 Mazda Miata with a warmed up Ford 302. The V8 Miata is making around 300 hp to the rear wheels and I've had zero issues over 4 years and 10,000 miles of sometimes spirited sideways driving.

The hard-to-fathom part of the story is the Miata's T5 is from a four cylinder Mustang with the small input shaft (have to run a pilot shaft bearing for a 87 diesel Ford Ranger in the crank). It's survived many many full throttle power shifts...The only reason it's still alive I suspect is a general lack of traction in the first few gears.

The above said, I'd have no problems with any T5 in a normally driven 350 powered truck. Of course I'd much rather have a WC unit from a later model vehicle.

Good Luck!

Been trying to read up on the T5 swap as Dad and I are researching what it takes, transmission wise for the drivetrain swap.

The stock driveline will come out to be replaced with a 283 SBC and I have a spare 2nd gen Camaro rear axle (need to measure to see if that will work).

But the million dollar question, what "general" year trans should we target? I know it dep new on the overall combo but looking to see what we should look for or what cars/truck years we should stay away from too. What is too new, too old, etc.

I assume the S10 T5s are hydraulic clutch? Is that any issue for the 50s trucks? And do you use he stock truck pedals??

Thanks!

Also, what is a "good" price for a T5?

I'd like to have an idea so if I run across one that sounds good, it would be good to know if we should jump on the deal or not.

Read everything that Lugnutz has written. You need an S10 tailshaft and I'd get a 14-spline Jeep input shaft. Speedway has a 14 spline clutch that works well. You'll probably have to custom make your shifter.

I bought a used T5 out of a mid 80s Camaro for $80 and it was in good shape. I spent $50 on an S10 tailshaft and labor for a local shop to check it out, shim it and bolt on the tailshaft.

Jeep shafts come in 14 spline or 10 spline versions. The 10 spline version allows you to use the common 10 spline clutch package (same as the factory clutch). Speedway sells a 14 spline clutch which according to everything I have read, is the best choice if you want to stay with the S10 or V6 Camaro 14 spline input shaft.

My preference is to do a 10 spline Jeep shaft swap for an S10 T5. For a V6 Camaro, it's a toss up. The input shaft splines are cut along the shaft much further than the S10. Therefore the clutch disc won't bind. Just cut a little off the pilot tip and install a Speedway clutch disc and away you go. Of course a tail housing swap and case cover is needed too.

That's all for now.

Any certain year S10 transmissions that you prefer?

Just trying to figure out how to narrow the search!

Perfect info!!!

You bring up super good points. We want to keep the stock bench seat and stock speedo. So that helps a lot, as I'll see for a 1988-earlier S10/S15.

For one in unknown condition, what would you consider a price that you would jump on? Saw a few early 90's ones where locals wanted $500 which I thought was a little high, but can't use those anyway.

If the S10 T5 has a cable speedo output then $250 is fair if condition is unknown. If the same cable speedo S10 T5 has been gone through and has a guarantee then $500. Rebuilt then add another $200.

I suggest that you find an S10 T5 with a 0.72 OD even if it has a VSS speedo output. Drive it and use a GPS unit to know your speed. Later you might find a rare 1988 or earlier S10 T5 with a cable speedo. That would be a good time to swap. I look for those 1988 and earlier units almost daily on CL and I usually only find 2 a year.

I sometimes find a decent S10 T5 at my local Pull-a-Part for about $130 plus I have 30 days to return it for any reason.

When I find them on CL it's more of a gamble. Maybe less of a gamble for me since I usually can repair simple stuff. I have extra parts in case you need something. Just ask.

I am always amazed how much people want for a transmission even though they have no idea if it's ready to be put into service. For the T5's with a VSS speedo and being sold "as is", I won't pay more than $100.

Would this still be a 1988 - or earlier unit, or what year are you referring to here?

The S10 T5 from 1983 - 1993 have the Muncie style case. The VSS speedo is found on 1989-1993.
The Cable style speedo connection is 1988 and earlier. I suppose there are rare exceptions within the 1988-89 time period.