So... get ready, long read.

I recently toasted 4th gear in my stock 99 GSR trans. It has an OBX in it that I installed, so everything else is stock.

I decided to use my little brothers spare 93 LS trans gear set to replace my broken parts with. So we bastard-ized it.

I used the GSR Final drive (4.40 I believe) on the GSR LSD (OBX), with the GSR main and counter shafts. I changed over the 3rd, 4th, and 5th gear sets from the LS to the GSR shafts.

Problem I ran into was the 3 to 4th on the main shaft has to use the LS fork. But it's loose and it seems to be holding the case up making it super tight. And when assembled the gears don't shift at all. I'm thinking something is up with the cable LS 3-4 shift fork.

Is there a difference between the cable and hydro LS 3-4 shift forks??

Thanks for your help!!!
Russ

 

well I did some searching and from what I can find the cable and hydro LS 3-4 shift fork have the same part #s. Not sure what to do now, any ideas would be GREATLY appreciated!!


Should I also use the reverse gear and reverse selector from the LS or keep the GSR?

Thanks guys.

 

did you use both gears for 3,4,5, the main and counter shaft gears?

 

Yes both the main and counter shaft gears from the LS. I learned that pretty quick, I had originally thought I could use just the counter shaft 3rd from the LS. But once I counted the teeth I knew they both had to be used.

So they are 3rd, 4th, and 5th Main and counter shaft gears from an LS trans. In a GSR using the GSR shafts and LSD/Final drive. Only other thing changed is the 3-4 shift fork is from the LS trans.

 

You may have installed the 3-4 hub upside down. The GSR has the opening to the U shaped lock towards 3rd gear and the LS has the hub installed with the U opening towards 4th.

Did you use both the countershaft and ring gear as a set from the GSR?

 

well I believe we fixed that last night actually. 3-4 sleeve is opposite of the GSR one we took off just as you described.

I used the GSR shafts, GSR ring gear and GSR diff (OBX). Only things changed were the gears (3,4,5) and the 3-4 shift fork. I believe.

 

Here's some pics of how it sits right now, and a pic of the 3-4 collar/sleeve.

They should show in this order, Main shaft (input), then counter shaft, then the 3-4 collar/sleeve showing the U opening upward toward 4th.

 

3rd/3th fork doesn't look right at all in terms of how it fits with the sleeve. Also did you replace the aluminum crush washers for the detent bolts?

 

that's what I'm talking about. Its the Stock LS 3-4 fork, with the LS sleeve/cuff. And it fits really loose. Which I believe is causing it to not change in'out of gear properly. It also makes it VERY hard to get the case together. Where, if I leave that one fork out the case will drop on very easily and all the way down ready for the snap ring. With the 3-4 LS fork we have to force the case down to get it snug against the C/S bearing and flip the trans to make the C/S drop so we can get the snap ring around it. Really frustrating.


As far as washers, not sure which ones you're talking about, or how that would effect anything. Please elaborate. Thanks for your help.

 

The GSR 3-4 shift fork is much wider and doesn't fit on the cuff/sleeve at all.

Would it hurt me much to use the GSR 3rd gear set with only the 4th and 5th from the LS. Is that possible to do?

 

The dentent bolts (12mm head, they're hollow and have a spring inside that pushes up against a steel ball, that ball fits in a notch in the shift fork shafts/poles and is what keeps the transmission in gear. If you don't replace the crush washers when you remove the bolts it can cause the shift forks to bind.

 

oh yeah, that should've been obvious. I'll look into getting new washers. But I don't believe that is the real issue we're having. Since we don't even have those ***** in when installing the case and it's still binding with just that fork. Without that one fork the case seems to go on much easier.

 

The forcing is not normal but getting the lock ring to snap in, you have to flip the case over, sometimes even "bounce" it for it to seat in properly.

My preffered methods are either the belly roll or HeMan method.

HeMan method: Pick up tranny quickly then quickly snap it back down.

Belly Roll method: Pick up tranny of workbench rolling it onto your stomach and chest, listen for the click.

I might be a redneck......but it works!

 

Flippng it is alright. But forcing the case down to get it snug againt the c/s bearing isn't right. Something is off.

 

I use the "old man" method and lift up on the countershaft nut with a prybar.

 

so is there any reason the LS 304 shift fork shouldn't work? Any suggestions there?

Should I try to only use the LS 4th and 5th gears and leave 3rd the GSR and use the GSR shift fork?

This is making my head hurt.

 

The LS and GSR have two different size gear cones, synchros, hubs, sleeves, and forks. You must use both C/S and M/S gears from the same model along with the other parts listed. Check again to make sure you are using the correct fork for the LS sleeve. The sleeve should fit in the fork like the 1-2 and 5-R fit. If it is looser, you have the wrong fork. If you are sure you have the correct fork and all the related parts are from the same model transmission, something is assembled wrong or bent.

Hope this helps a little.

 

Yup, I'm sure the sleeve and fork are the correct ones. This picture is how it is currently assembled. As far as I can see they are perfect by every picture I have found. They were in a box with the whole LS gear set. It is possible that the box was dropped hard enough to slight bend the fork. Just seems very strange that is looser than the others.

So using the GSR 3rd with LS 4th and 5th sets will not work, it it will?
I think I tried that and the 3/4 sets have to stay together due to sizing of syncros and cones like you mentioned. Just wanting to clarify.

 

I don't think you would have bent the fork by dropping it to close the cases. The picture looks like the fork is too large for the sleeve. Measure the opening of the fork: LS= 75mm GSR=81mm. It is possible that someone was into the LS transmission before you opened it. Was it an operational transmission that worked? You can not mix and match the 3-4 gears between GSR and LS. They must all be used a a match set with the correct related parts.

 

that's what I thought on the 3-4 sets.


The LS trans the gear set came from was fully functional and we believe to be bone stock before removed. I'll measure the sleeve and the fork tonight and see what we find. I just want my damn car back!!!!!!!!!!!!!! arghhhhhh!

 

anybody got a 4th gear set just the gears c/s and m/s from a GSR they want to sell on the cheap. Or know anyone with them?

 

I might, but I'm not sure. I junked out a LS and GSR tranny. Customer wanted two POS made into a shiny turd. After I told him it would be $600 in parts I never heard back about what to do.

It sat for about 1.5 years, parts got mixed up, I'm scrapping all the unknown gears.

 

Well let me know what you find out there. I'm def interested in them. Even if you just put them all in a box mixed up and send 'em to me. I'll sort through them, count it and identify them. And see what I can use. If you're just going to toss em.


Thanks for the help guys. Something is def up with the 3/4 shift fork. I just don't know what, or why!

 

alrighty... I just picked up a Hydro LS gear set. The 3-4 shift fork, and sleeve/cuff are totally different than the cable set I got. So I'm gonna try using the hydro gears and 3-4 fork and see if it works better. I'll update tonight or tomorrow. Got something other crap to get done to day, I'll try to slap it together tonight though, sometime.

I'm gonna use the GSR shafts, with the hydro LS 3-4 set on both shafts, and the cable LS 5th set from the cable since its a hair shorter. Gotta keep it somewhat close ratio so I can stay in boost between shifts hopefully.

Updates coming.

 

Well... After some teeth counting and mark checking and lots of head scratching its back together. Used the 3rd, and 4th from the hydro ls and 5th from the cable ls. On the GSR shafts with GSR diff.

Will be putting it all back in the car tomorow and testing it.

Thanks for all the help guys!!!!