Transmission for '85 S-10

I have a 1985 Chevy S-10 pickup truck that is having an argument with 1st gear. The previous owner put a succession of transmissions in it and I believe there is a '94 in there now. I plan to go to the junk yard to get a used one for cheap. How do I now which transmission will fit in this truck? Thanks!

Automatic, right?

What do you mean it’s having an argument with 1st gear? What are the specific symptoms? A possibility might be that it wants some sort of computer input that the computer in your truck (if it has one) isn’t giving it.

I’d have bet against a '94 transmission easily fitting in an '85 truck. Who knows what the previous owner had to do to get the thing in-- this truck might not take an '85 transmission anymore.

I forgot to specify that this is a manual transmission. Sorry. Specifically, the synchros for first gear are probably worn. It does not want to mesh going into first, but I can usually get it to stay in gear after a couple attempts. There is no computer in this truck. The current transmission was obtained by the previous owner from the junkyard and was the third transmission, having replaced it twice. There were no modifications made as far as I can see. Obviously, I don’t have to hunt for an '85 transmision. My original question is, when I go to the junkyard, what am I looking for in a transmission? Do I have to come equipped with measurements of the bellhousing and the length? Or can I find any transmission that is [fill in the blank]? The truck is only used for occasional hauling chores and driven <1000 miles/yr. I can get a used 5 speed transmission at Pull-A-Part for around $45 so I don’t have much to risk. Thanks!

Your complaint is a bit fuzzy to me.
You can get it to “stay in gear after a couple of attempts”. Does this mean it’s jumping out of gear?

Does not want to mesh can point to a dragging clutch. Surely someone did not go to (multiple) transmission replacements without installing a new clutch assembly?

Okay. I’ll be more specific. It grinds going into first. There’s a clear feeling that it is not lining up correctly. It’s fine going into all other gears. I can sometimes slip it into third, engage the clutch slightly, then get it into first. Sometimes that works, sometimes not. Depends on whether I’m holding my tongue right. Sometimes I just have to start in second but that requires more slipping of the clutch than I care for. And yes, it sometimes pops out of first. That used to be the sole symptom until it started becoming stubborn going into first at all. I can’t vouch for what the previous owner did, but he took pretty good care of the truck, did all the work himself, and I assume he would have replaced the clutch when he had the transmission out. The clutch feels fine, grabs appropriately, and doesn’t slip. I even tried the trick of nosing it up to a tree and trying to start it out in 5th. The engine died immediately.

5 speed right? Should be a T5. They were used in tons of stuff. S-10’s from '83ish to '94ish, Camaros from the 80’s, firebirds, etc. If you find a GM car from the 80’s with a 5speed in it, it’s likely a T5. You could get one from another car and use your tailshaft housing if necessary. I’ve got an S10 T5, with a Camaro tailshaft housing, in my vette. Very interchangeable trannies. Run a search for “T5” and see if it looks like your trans. My last one only cost me 50 bucks on craigslist. They’re everywhere.

Popping out of first means an internal transmission fault; worn synchronizer hub, sleeve, hub inserts, etc. or possibly even excessive end play in a main or countershaft.
Any problem in that area could possibly lead to grinding going into 1st gear.

At what points does the clutch disengage and engage?
In other words, how far off the floor is the pedal when you first feel the clutch grabbing.
When depressing the pedal how much free play is present before you can feel the clutch?

(Just trying to determine for sure if the problem is synchronizer assembly related or clutch related)

Ah, nevermind… manual transmissions are a whole other story!

Although, have you ever priced out a new or rebuilt one? You can probably get one for a few hundred bucks and, along with a new clutch, you’ll probably never need to worry about the transmission again. Or have you thought about rebuilding one yourself? Anyone with the mechanical aptitude to actually swap out the transmission should have no problems rebuilding a manual gearbox-- they’re pretty simple little devices.

A heads up on the T-5 transmission. There are plastic inserts over the shifter forks where they engage into the groove on the gear clutch sleeve. These do wear and can crack. Also the metal of the shifter forks where these inserts are attached are rather light and can break off.

If you are not at the point of popping out of gear; if the main complaint is that you have to push hard to get into gear; and if shifting is okey when the engine is stopped, you probably have a dragging clutch. This is different from a slipping clutch. If it grinds going into reverse that is another sign. The cause could be the release linkage (hydraulic) not fully releasing the pressure plate; axial runout of the disc; a disc that does not slip freely on the input shaft splines; a wear step in the input shaft splines; dry or gummed input shaft splines; a dragging pilot shaft bearing; the wrong oil in the transmission; or just a bad syncronizer.

Later model T-5 transmissions had doubled first and second syncronizers. I believe these are called “world class” transmissions.

Give us feed back on this.

Wow! Thanks to everyone for the great replies. I’ll address some of your questions and comments. First, as for the clutch, there’s about an inch of free play and the clutch begins to engage around 2.5" from the floor. The clutch isn’t hard and works fine in all the other gears. I replaced the hydraulic master cylinder within the last couple years. First gear doesn’t always mesh easily. Even when the engine is off, it can be reluctant to fully engage. For example, when I’m parked on a slight hill, have turned off the engine, and slip it into first to park, as I let out the clutch, I can hear and feel the teeth slip past each other. When it goes into gear, there’s a sort of “click” - it’s hard to explain - that I feel when know it’s likely engaged. Even then, if it’s not fully in first, it will pop out of gear, but this is infrequent.

The info about this being a T-5 is invaluable! Indeed, there’s a lot of info out there. Even the service manual which I found here: It is tempting to think about rebuilding the thing myself and I don’t doubt that I can do it (especially now that I’ve found the manual). However, like most DIYers, having the ability doesn’t translate into having the time and, like most others, I have far too many projects going as it is. I appreciate the tip about finding a later model and that’s probably what I’ll look for when I hit the junkyard. I don’t know what kind of shape the clutch is in, so I’d have to pull the transmission to replace it so I might as well pop in one from the junkyard while I’m at it.

The last clutch I replaced was on a Ford Escort. This looks like a piece of cake in comparison. Heck, I can crawl underneath the truck without jacking it up! I had a mysterious problem after reinstalling the Escort transmission which I sent to Car Talk as a puzzler, but they never used it. The solution involved buying a borescope which subsequently has been great fun for looking into birdhouses, down crawdad holes, and into a mysteriously clogged toilet.

Again, many thanks to one and all for your knowledge and experience. It’ll help me keep the old truck running for many more miles.

A couple of heads up comments. If you get a replacement transmission, see if you can hold onto the input shaft of the old one because it makes a great alignment tool for aligning the clutch disc to the pilot bushing. It is easy to remove from the transmission. Just unbolt the four bolts on the input bearing housing; pop that off; and pull out the input shaft.

If you take the transmission apart the front counter shaft bearing has to come out toward the front. If you try to press it to the rear you will crack the case. The overhaul manual recommends only removing the front counter shaft bearing if it needs to be replaced with the warning that it will probably leak afterward. As I remember the removal procedure is to press down on the edge of the input counter gear from the front to dislodge the rear bearing and remove the counter gear cluster then to press the front bearing out from the rear.

If you fiddle with the gear selector, make sure you mark the orientation of the cross over interlock as it seems to have a different cut on each side but I have found no information on which side goes where.

If you are mechanically inclined and willing to experiment this is a good transmission to work on.

Good luck. Let us know what you learn as you progress.