4T60e Replace or Rebuild

[95MonteZ34]

Hi everyone,
I'm new to the forum and I'm looking at buying a 95 Monte Z34 with a bad Trans. 133k on the car, motor has been maintained well however the trans blew a cooler line and fluid is now black. Not sure if the trans works, but I plan on doing a service and normal flush just to see. However, if there is a bunch of debris in the pan I don't see much point.
I have plenty of experience to do a rebuild however, I was hoping to swap in a good used trans while taking time to rebuild the original. (I don't have the space for the car to be down long)
I have heard its not quite worth doing a swap and that a rebuild with updates would be the best.

I would appreciate some info on:

1. Which transmissions will work in the car to do a swap?
2. Which master kits are folks using for the rebuild?
3. Which upgrades/updates are worth it? (i.e. 3.73 diff gears)

I would appreciate your opinions on what would be best to do with this car. Thanks in advance.

[3400-95-Modified]

I believe you COULD use a 94-99 trans in that car... I've swapped a 99 Buick trans into a 95 Beretta and the only difference was the 3.29 Final drive vs 2.93, Being a 95 it didn't care and didn't have a trans component slip code like the 96 does, You have to update the drive/driven ratio in a 96 when it's changed. Depending on what you pull it from the side cover may differ, which is also an easy swap.

I still tend to get my parts from Bulkpart.com and transmissionpartsusa.com

I also pickup my clutches from Alto dealers as well as WITTrans.com they have the Raybestos red pack if you want to go that route.

Best Master Kit's will be Borg Warner which is mostly what BulkPart deals with, I'm not sure what brand TPA uses.

Best updates are the reverse shell since that was not originally hardened, the 4th clutch hub, same issue... and the TCC teflon ringed valve from TPA as well as the TRANSGO shift kit which is really just a broad range of fixes. I combine the ones they with some of the new valves when I do a trans. Sonnax does offer teflon coated valves for all the shift functions... I do that on ones I want to beef up, they are not 100% necessary.

[95MonteZ34]

"I believe you COULD use a 94-99 trans in that car... I've swapped a 99 Buick trans into a 95 Beretta and the only difference was the 3.29 Final drive vs 2.93, Being a 95 it didn't care and didn't have a trans component slip code like the 96 does, You have to update the drive/driven ratio in a 96 when it's changed. Depending on what you pull it from the side cover may differ, which is also an easy swap"

Great info thanks, So does it matter on the used trans as far as each gear ratio needing to be the same as the original for power band to remain correct. Obviously it would stay the same, but does the engine lug or have other issues(i.e. throwing codes) if the gear ratios get taller. ( I have heard it can, but you know how hear-say goes!) Anything better in the final drive of 2.93 would be good. Also im not sure what you meant by the side cover and swapping, but im assuming if you use a 99 trans you have to change some valve body components.
Sorry for all the questions im totally new at swaps for GM cars in these years. If I could upgrade a bit with a new used trans that would be good and maybe a little easier. Thanks for the reply and I will continue to research myself, but keep the advice coming.

[3400-95-Modified]

You would have to take the side cover type used on your car and possibly put that on whatever donor you get if it's different. There were 2 different versions through the years depending on the body style and mounting used.

No valve body changes are necessary at all... hence why I said Only the cover and drive/driven ratio will be different. The 2.93 ratio to the 3.29 ratio is a gain in gearing and the car will turn more RPM per mph which will give you a snappier feeling... I'm not sure what the ratio is in the current trans, you'd have to post up the tag off the back of it to verify but being a Z34 it may already be 3.33 or 3.29... Most 95's were already converted to the new 3.29 diffs from the 94 and older 3.33's but some models continued to use the 3.33 style. There are really only 3 interchangeable diff's in these transmissions but the 3 drive/driven chain setups give you 9 total gear ratio combinations. There were many other changes in the diffs such as the described 3.33 to 3.29 but the gear cut was also changed so those two are not interchangeable... There are actually 9 different diff's but only 3 per gear cut/direction that can be interchanged. It's confusing to explain on a forum to say the least.

I wouldn't concern yourself too much about the "power band" since you will feel a benefit if you drop from 2.93 to 3.29.

Page 13 of this document has the 2 side cover's listed.

http://www.shinseiauto.com/japanese/transtar/usgm4t60e04.pdf

[95MonteZ34]

Just a quick update for this thread
I did purchase the car for $250. Once I got it home I fill the trans and it worked through second gear. Did not go faster than that to see if the rest of the gears worked due to the extension housing being cracked. The diff pin sheared its roll pin and was thinning the housing as it spun with the carrier, hence the black fluid. I have a new/used carrier and housing I'm putting back on the old trans. With a good flush will see if it works fine or will need more attention. If everything else checks out ok with the car I think I will rebuild a core trans and install it in the spring or summer. Will update.

[3400-95-Modified]

It will need more attention... this happened to one of my transmissions and the VB started to stick after it happened... Just think all that aluminum is making its way through the transmission and jamming everything up.

[95MonteZ34]

It will need more attention... this happened to one of my transmissions and the VB started to stick after it happened... Just think all that aluminum is making its way through the transmission and jamming everything up.

Yeah I would not be surprised if more issues arise, but hopefully at least it will just move around for now until I get a chance to get the transmission rebuilt, replaced, or whatever im going to do with it. I may just drop the vb and clean it out if the trans does not perform ok. Thanks for the heads up on that one. The trans is not the only issue with this car and im not sure what else ill find once rolling. It already has the no idle/runs rough when cold issue. I'm going to tread lightly on the amount of money im putting in it until I know the extent of all repairs. The trans parts were free so I only have time invested so far. I'll post back when I know more.