The Stovebolt Site Forums The Shop Area Engine Shop T5 transmission

I am writing to see if anyone can tell me more about my transmission. I bought a T5 from a 2wd Chevy S10. Near as I can figure it is a 1989 model. There is a tag on it, but it is so thoroughly rusted that nothing can be read on it. Here is a picture:

T5 transmission

Here are some other numbers.

The case Basic 4 1352-065-916 cast Aug 88
The lid Basic 2A 1352-097-917 cast Aug 88
The tail housing 1352-066-931
Shifter plate 1352-598-044
Serial number on case CK2106112

I measured and calculated ratios to be:

1 4.00:1
2 2.38:1
3 1.48:1
4 1.00:1
5 0.86:1

On a chart Inliners T5 page I found some numbers. The chart shows ratios of 4.03, 2.37, 1.49, 1.00 and 0.86 for early S10 transmissions.

With the casting dates and the fact that I have an electrical connector for both the backup light and the electronic speedometer, I am guessing that I have a T5 from a 1989 2WD Chevy S10.

There are 2 model numbers that I have found. I think one of these is what was on the rusted tag.

1352-191 is a 1989 GM T-truck 4 cyl
1352-193 is a 1989 GM S-Truck 4 cyl

Can anybody tell me what a T-Truck is vs an S-Truck? Was the T-Truck the S10 Blazer?

I have figured out that it is a NWC (non-world-class) vs a WC (world class) transmission.

I found a table somewhere that listed the gear ratios in a 1989 S-10 and I just can't find it. However, they were completely different than what I have listed above.

Can anyone shed some light on this?

I can't really tell you much about the trans, but as to the "S" and "T" thing, the S truck/Blazer is the 2wd, T is the 4x4.

The tag #1352-191 specs out to be a "Light truck" 4.03, 2.37, 1.49, 1.00 and a .72 5th gear. This came from:

http://www.ttcautomotive.com/English/products/T-5.asp

However, I find from another source that tag #1352-191 lists as a 3.76, 2.18, 1.41, 1.0, and .72 5th. This source also shows the same ratios from an S-truck for the 1352-193. I think these chart came from the Tremec site....doesn't have any url on my copies.

Dave

I can,t tell from the photo but if it has the electronic speedo drive it is 88 up. This creates a problem if you are useing it in one of the older trucks. You have to use a custom gauge or a special converter. Or you have to change the rear houseing & speedo drive gear.

Thanks for the info. Fla54Chevy3100, the table was great. It looks like I might have either a 1352-000-216 or 1352-000-257. Is there any way to figure out what year they were produced? Mine says Borg Warner on the case. I know that Tremec took over production at one point and may have either used the Borg Warner cases or had part numbers for overlapping production. My guess is that that lower number (216) makes most sense.

Thanks again to everyone for the help.

Todd, a tag 1352-216 indicates a 93 S10 behind a 2.2L while a tag 1352-257 is from a late model Nissan 4wd w/transfer case. Doubt that you have one of those!!! A 93 s10 will have an electronic speedo setup....on page 10 of my Webshots "shoebox" I have pictures of both the mechanical and electronic setups.

I wouldn't discount an electronic setup....granted, the converter box @ $300 is pricey, but so is rebuilding an older high-mileage T5 with a mechanical speedo. You might get lucky and get a T5 that is in better shape internally.

Dave

Dave,

I am not too concerned that mine is the electronic speedo. My gages would need totally rebuilt or replaced anyhow. I may just buy aftermarket electronic gages as I would like to have a tachometer as well. I really suspect that I have a 1989 T-5 because it has the Aug 1988 casting date on two of the parts. It just seems that from the information I have seen, the 1989 S-10 2WD T-5 did not seem to come with the .86 5th gear that I seem to have. I am going to try to calculate it out again, but that is what I get so far. I will eventually take it to a shop to haveit looked over and maybe have the synchros replaced. I will check the number of teeth on the gears as well. That should give me an accurate calculation.

I saw how you modified the splines in the T-5. I assume that you cut back on the outer collar as well. It covers up part of the splins on mine. I am going to try to use the Vega hub / Astro Van clutch disk combo. That may negate the need to extend the spline grooves.

What rear end ratio did you end up with? I had been thinking aobut 3.55 gears. I bought a 12-bolt posi, but it has 2.73 gears. (Too tall) If I really do have the .86 overdrive, I might be better off with something like the 3.42 gear.

Did you have any concern of axle tube warpage when welding on your spring perches?

What size tires are you running. I am 90% planning to buy the Jim Meyers IFS with a manual steering rack. On another thread it was suggested that I shouldn't use a tire wider than 215. I would like to use a 225 or 235 tire on all four corners, but am concerned about the steering. I guess I should get around to callin Jim Meyers and asking what they think.

The chart I use shows all 88-89 S-10s as haveing 3.76 first & 0.72 fifth.

Hi Todd,

There are 2 common S10 OD ratios in the NWC T5's, the .72 and .86. I found the easiest way to differentiate was to put the transmission in 5th gear, mark both the input and output shaft at the 12:00 position. Rotate the OUTPUT shaft (rear) 360 degrees and observe the position of the mark on the input (front) shaft. If the input shaft has rotated less than 270 degrees your ratio is more than likely .72, if it's rotated more than 270 degrees it's more than likely .86. Not an exact science by any means, but able to be done at the j-yard before you pay for the box.

Based on what I'm running....the .72 OD, 3.42 R&P, and a 28.5" tall rear tire. Most of my driving is either around town or on the 4 lane...not much 55 mph stuff. First through fourth are great in town...you don't stay in 1st gear long even with the 3.76 ratio and you can putz around at 35 mph in 4th with no lugging. OD for my 70 mph cruise has me spinning a conservative 2000 rpm's and have no problem dropping down to 45-50 and accelerating with traffic. Fourth gear at 70 mph is well under 3000 rpms.

I'm very happy with my Camaro 3.42....tried the 3.08 but it was way too tall for the .72. You'll just have to run the numbers, keeping in mind that the 235 sweet spot is between 1700 and 2400 rpms for a basically stock engine. I think I mentioned before that a 3.73 might be a viable alternative with a .72 if you lived in the hills/mountains or were wanting to pull a trailer.

As for axle tube warpage, I used a stick welder, ran short beads and used a wet towel to control the heat. I've noted no problems.

I used 255/70/15's on 5 lug 4-3/4" pattern 15X8 with 4" backspacing (62" wide Camaro diff) and 235/70/15's on 15X7 with 4" BS on the front. I have no clearance issues but would recommend 235/70/15's on 15X7 with 4" BS all the way around. This would allow you to rotate your tires and give you a more level stance. BTW...the 15" rims clear the front 5 lug disc conversion and tie rod ends with room to spare.

As for the steering, I am still running the stock steering box, 18" steering wheel, and 32 psi tire pressure. Power steering (Toyota) is down the road. I also lube every 1000 miles.

Hope this helps.

Dave

Wrenchbender,

That is what is confusing to me. I don't know if castings made in August of 1988 could have been used in 1990 or later transmissions.

I will have to go and check the rotation in 5th gear again.

Dave,

Thanks for all the info. I agree that I would like to use the same size tires all around. With my planned use of the rack & pinion steering, I will have less turns lock-to-lock and thus less leverage to turn the tires. I don't know if anyone elase here has had experience. Like I said I have had one person tell me that 215 would be the max width, but I would rather have a 225 or 235 width and don't know if that will necessitate power steering. I am using a 235 6-cylinder and not a small block so it might be complicated to add power steering.

I ordered a clutch with the Vega hub for clearance purposes. Here is a picture of my input shaft.
T-5 input shaft

I have seen others where the collar around the shaft is not as long. Can anyone tell me whater I will need a spacer plate or maybe have to cut this collar back to avoid interference?

Hi Todd,

I just noticed your pic showing the throw-out bearing pilot shaft in it's stock length. Hopefully, if you're not going to use a spacer it's going to have to be trimmed 1-1/4 to 1-3/8". I have a picture (#57) in my webshots "Shoebox album" that shows the bearing pilot after trimming and some things I learned about getting the clutch pack to function flawlessly. I took the time to document the process so others won't have to do the R&D. I hope it helps with your modifications and install.

To trim the pilot bearing retainer shaft, you want to remove it (4 bolts) from the transmission. There is a little seal that needs to be cleaned of cutting debris after the pilot shaft is cut. If you use an air cutoff tool you'll contaminate this seal and can have gear oil residue on the input shaft.

BTW...my T5 has been on the road for 16 months and is driven every day, so this is not an opinion....but a fact.

Dave

I'm in the process of changing my transmission. We have talked on forum before. I noticed on your pictures you have converted the front to disc 5-lug. What is the least expensive way and what bearings did you use. Did you buy the calipers and rotors from AZone? What about the mounting bracket. My truck is a late '55 Task Force.

Dave,

Thanks for the help. I do have a link saved to your webshots. I used the Vega hub in a 10" clutch. That was the first step. I will see how much of the collar I need to trim back. Then if needed I will make a spacer I think. I want to try to avoid any grinding of the shaft itself if possible.

I also bought a 12 bolt. It has 2.73 gears. I think I might want the 3.08 ratio. My T-5 has a .86 overdrive not the 0.72 you have. How did you like the first 4 gears with the 3.08 vs the 3.42 ? I am targeting tires of about 27-28 inch diameter I think.

Todd Maxwell

Hi MBT and Todd,

5 Lug conversion: This conversion uses GM rotor/hub combo with stock bearings and a spacer which comes with the bracket kit from CPP. The rotors, calipers, hoses and pads are specified in the CPP installation instructions and you purchase them from your local parts house. In contrast, with the 6 lug conversion, you have to use a pricey ($119.) custom bearing from the vendor as opposed to the $30. bearings for the 5 lug conversion. Being able to replace a bad wheel bearing without waiting on a mail-order vendor was a major influence on my 5 lug decision. The major downside of the 5 lug kit, is that you will be buying new rims with 3-5/8 to 4" Backspacing. The j-yards don't have them as I hit 3 big yards to come up with one beat-up rim for a spare mount. I was going to buy new rims so the 5 lug worked best and gave me a good selection of reasonably priced rims with the correct BS.

Todd, for your install, you're going to have to trim the bearing pilot regardless of the spacer thickness. If you cut your input shaft and pilot brg shaft, and just gently open up the bottom of the splines so your disc slides another 1/4-3/8" past the end, the clutch pack will fully release. You might be able to trim your disc flange a tad as added protection. As I pointed out in the pictures, the key is to make sure that the disc actually slides past the end of the factory splines to fully release.

Gearing: Based on my truck....basically a 261 grind cam, no HEI, 3.42, .72 OD and 28" rear tire diameter.

My goal was to have gearing so I could use my 5th gear without downshifting when slowing down to 45 mph (1330 rpm's) and to accelerate with normal traffic flow back up to cruise speed without lugging the engine. Keep in mind the 1330 rpm number as being close to the very bottom end of the useable torque curve. For cruising I run at 2000 rpms at 70 mph in 5th gear. In reality, this is a bit lower rpm than the true "sweet spot" on my engine. It really likes to run at 75 mph@2216 rpms. However, that's not really comfortable for me as a lawbiding driver, who isn't really in a big hurry to get anywhere!

IMHO...with a 3.08 R&P and a .86 5th gear you would fall right into the lower end of the torque band (45mph@1483 rpms) and be able to hit your gearing sweet spot at 65 mph@2143 rpms. You would still have plenty left if you wanted to cruise at 70-75 mph@2400 rpms. This would also let you run in 4th gear with a load or trailer at well under 3K.

As for the 2.73 with the .86 OD...it would stretch out your 1st-4th gears but you'd be really flat in 5th gear until you got up to 60 or 70 mph. That's what I faced when I installed the 3.08 diff with the .72. Worked great as a 4 speed, but was just too tall for normal driving without constant downshifting.

I hope this helps you guys with your decisions.

Dave

Dave,

Sounds good. I probably don't have the "optimum" T-5 because it doesn't have the .72 5th gears, but I think that mine will work fine with the 3.08 R&P. Thanks for your analysis.

I had hoped to not have to modify the transmission input shaft based on the tech article that was posted here describing the use of a Vega clutch hub. I am taking my T-5 to Nebraska for Christmas where my father-in-law is building the motor for me. We are going to work out the clearace issues while I am there. I had hoped to bring the motor home with me, but I have been waiting for nearly 2 months for the camshaft. My supplier is reputable, but he has had nearly 30 of the backordered from Iskendarian (sp?) and they keep getting told "Any day now". Oh, well. I don't have the frame done to put it all in yet, so I guess I am in no real hurry.

What would it be with a 3.55 rear?

Using 27 inch tire diameter, 3.55 gears and .72 5th gear, 65mph would be at 2068 RPM.

With the .86 5th gear I have the RPM rises to 2470.

Here is a RPM calculator. It has two ways to enter data. I use the bottom half of the page.

Engine RPM calculator

Thanks, Todd