Hello,

After last weeks debacle of a wobbling 5th gear mainshaft gear, I have made a new discovery and I am kinda at a crossroads of where to go.

I took my 5th gear off and found the number to be 1352-070-022 which turns out to be a 28 spline, 27 Tooth 5th gear for a 1985-95 Ford Mustang 5.0L. So it seems that my main-shaft is actually a 28 spline unit. The guy I bought the tranny from showed me the thirdgen he took it out of and he said that he had rebuilt it before. I went ahead and counted the input shaft and it does indeed come out to match a Chevrolet input.

My question is should I go ahead and continue trying to get the replacement t5 mustang gears or should I just go all out and get the correct GM Mainshaft and 5th gear. If I go the GM route will I also have to buy the corresponding 1&2 gears if they are mustang gears, or are they interchangeable?

Is it common for people to rebuild the t5 with a mustang output? I know that the mustang unit is supposedly stronger.

 

It is not stronger except in two ways.
When they used the V8 third gen gear ratios and made a big deal of it as if it was new.

And only in the T5-Z sold through FMS ( and one production model around 93) the use of a tapered bearing for the pocket bearing between mainshaft and input. That mainshaft is 28 spline and machined differently at its front end. I believe the 28 apline yokes have the same o.d. as the 27. Would I change slip yoke and machine a GM input in order to do this mod? Yeah but that's me. LOL. That bearing is the sole reason to use Ford T 5 parts.

Since yours has a GM input, it's probably a put-together from spares. But it would be cool if it hadvthe tapered.beariing.

 

Well, looks like I was wrong about the main-shaft, and I also found out why the original owner sold the transmission.

I didn't do what I should have done right away, and that was to trace all of the part numbers on my cores, gears, etc.

Come to find out my mainshaft is a 27 spline mainshaft. Apparently, a 28 spline gear will fit on the 27 spline mainshaft. In my last thread I found out that my 5th main-gear was wobbling. After checking, I found out that my shaft was straight. It was then I found out that the 5th gearset was out of a mustang, and I assumed that the mainshaft was of of a Mustang as well. I was wrong. While the 28 spline gear goes on the 27 spline shaft it doesn't seat correctly, which makes the wobble that I was seeing and feeling in it.

After going through the cores I have three separate transmissions. The 1989 WC T5, which is the one I'm going to use, just gotta get a 5th gear. The second transmission is a non WC T5 out of an S-10, the third transmission is a WC out of a Mustang.

Here is what I figure happened. The original owner told me that the lock ring came off the the main-shaft and ruined the original 5th gear set. However, I see no evidence of this on the rear of the case or the tail-housing. Whatever the issue was, the rest of the transmission works well, (shifting and spinning it by hand, checking endplay, and a visual inspection of the internal rings, etc.). At this point I believe the original owner went out and bought the s-10 T-5 to replace the 5th gear. Since it was a non-WC unit, it didn't work. He then bought the WC Mustang TV and assumed that the 5th would work, as I did. I'm guessing at this point he just gave up and sold it to me.

Fortunately, with the internet, and everyone's help I have been able to figure this whole thing out. I will say though, it seems like a T5 is a hard transmission to get good, straight information on. The variety and model changes (WC to non-wc) makes research into parts and what works and does a headache. Hopefully, I finally have the answer I need and can get this tranny back onto the road.