'85 GMC S15-4WD, 2.8L 4 SPD Transmission

[pullmyefinger]

I have a B/W 4 speed manual transmission in this thing, and people are telling me my mileage would be alot better if I put a 5 speed in because of the overdrive.

1. I was told by a local dealer that a 5 speed tranny would bolt up to where the 4 speed was with no problems?

2. What about the transfer case, does that need to be adapters? If so, what are they, where might i get them, etc.?

3. The only bad part about that is that those trannys are very old and i may be lucky to fine a working one and/or have to have it rebuilt very soon?

4. Since my 4 speed BW works fine, should i just forget about the 5 speed and maintain the 4spd till it dies?

Thank you for any comments you may post.

[lilpoindexter]

I don't know about 4x4's but i got a T5 out of an '83 S10 so i could get the tailshaft and shift rods that moved the lever forward, away from a bench seat. i put the Tailshaft from the S10 on a T5 from an 83 Z28. when i took the box apart i did see that rollers from a bearing had fallen out of a bearing cage...but it appeared to have happened after the truck stopped rolling because there was no damage to any other components from the rollers banging into anything. If the lack of over drive doesn't bother you, i would leave it alone.

[dragonball98312]

You dont have to swap out the 4 speed if you dont want to. Ive had a ton of s10s over the years. As long as the t5 you get was from a 4wd it should be a direct swap. Theyre transfer cases are the same. Tho make sure you get a 5 speed from a 82-88 s10 as 89-93 (94 blazers) use an electronic speedometer and 82-88 uses a cable. If you do alot of freeway driving the 5th gear will help alot.

[pullmyefinger]

Originally Posted by dragonball98312

You dont have to swap out the 4 speed if you dont want to. Ive had a ton of s10s over the years. As long as the t5 you get was from a 4wd it should be a direct swap. Theyre transfer cases are the same. Tho make sure you get a 5 speed from a 82-88 s10 as 89-93 (94 blazers) use an electronic speedometer and 82-88 uses a cable. If you do alot of freeway driving the 5th gear will help alot.

OK, so having the S15 4WD 4 spd Borg Warner should swap out direct with a 5 speed BW that had 4WD? The transfer cases are the same so they need no modifications?

I appreciate all the comments. I just wondered about keeping the 4 vs getting the 5 and getting a lemon that would be more money and headaches than it was worth. I understand that the 5th gear/overdrive would help mileage alot, and that is what I want to do cuz I do very little highway driving because the mileage stinks. Please let me know if what I said is true above and thank you all again!

[barry1982]

Hi There, Does your truck have a tach? What are you revving at 60 MPH? I had an 87 S15 4 x 4 Jimmy with a 2.8 V6 a a 5 speed standard. I don't know about yours, but mine was extremely "under powered" I almost couldn't drive it in 5 th gear. The slightest wind, or hill I had to shift to 4 th just to hold the speed limit.

[pullmyefinger]

Originally Posted by barry1982

Hi There, Does your truck have a tach? What are you revving at 60 MPH? I had an 87 S15 4 x 4 Jimmy with a 2.8 V6 a a 5 speed standard. I don't know about yours, but mine was extremely "under powered" I almost couldn't drive it in 5 th gear. The slightest wind, or hill I had to shift to 4 th just to hold the speed limit.

Interesting. I find myself downshifting alot just to get up to speed because that truck has no pickup. I have to watch getting off onramps because the pickup isn't there and it takes forever to get up to 55 or 65 to stay ahead of traffic. It's actually scary, wondering if highway traffic is going to run up my butt before I can get to 55+. No tach in the truck. Are you saying that truck isn't really meant for highway driving? That's fine, I can deal with it as long as I know. If that's what you are saying I think you are right.

[Warrens69GMC]

Well, gm had a 3.4L High Torque engine as a replacement for the 2.8L as many were complaining the 2.8L was underpowered.....


http://www.summitracing.com/parts/nal-12363230

[barry1982]

Yes, I don't believe the 80's S10, S15 4 x 4's had enough "grunt" with the 2.8 V6. It's funny, I had an 85 S10 2WD shortbox with the 2.8 / 5-speed standard and it wasn't too bad. I imagine the extra weight of the 4 x 4 equipment killed them. Not sure about the "smog" laws in your area, but you can get quite a bit more "juice" out of your 2.8 if you remove the Cat. converter. I did this on both of mine. Welded in a straight pipe, it helped but they are still not powerhouses by any means.....