Trans questions

[LokiZ34]

Trying to figure out what the best route to go would be I have a 96 Monte Carlo z34 I'm fixing to replace this transmission for a second time and I'm curious as whether it would be easier to rebuild a 4t60e with 4t65hd clutch packs if this is even possible I am coming up empty trying to find information on this if someone could please steer me in the right direction I would greatly appreciate the information

[55trucker]

How many miles on the current rebuild?

How many miles on the previous rebuild?

in both situations was the trans professionally rebuilt by a qualified rebuilder?

Behind the LQ1 that trans should be able to hold up to anything that engine can throw at it.

 

[LokiZ34]

The first transmission that was pulled as far as I know it was original to the car and one of the odometer quit which was before I purchased the vehicle it read 98,000 miles shortly after I got it the drive chain started slipping on the output shaft and it was having a little bit of issues before that.

The current transmission was bought from a junkyard with reported 85,000 MI and it lasted another roughly 35,000 MI before the third gear clutch pack let go so theoretically both Transmissions had over 100,000 miles each

Edited December 18, 2023 by LokiZ34

[55trucker]

Generally speaking there *part-in-parcel* is the issue when purchasing used items (such as a trans) from a salvage yard. One doesn't know what the history is on said purchase.

You have no idea as to how that trans was treated by the previous owner. Most vehicle owners do not maintain the proper service schedule on a trans, therefore it is more often than not neglected.

As for your situation, the clutches have shown to be slipping in both the trans that were/are in the car. Why are the clutches slipping?  More often than not the clutches are NOT the source of the problem but the result of a problem elsewhere. The 4t60-e makes use of a vacuum modulator to control the shift application of the band/clutches, the 4t65e did away with the modulator & shift control is electronic. The accumulators are the first source to look at where slipping is concerned, after extended use & lack of servicing the accumulator piston & the pin it rides on inside the accumulator assembly wears. 

Once the wear takes place the clearance around the pin opens up & the piston now wobbles due to the lost tight clearance & fluid pressure needed to apply the clutches is lost. Now the clutches begin to slip, then overheat & burn out, upshift/downshift becomes erratic, if left unchecked the trans eventually fails (which is where you are right now). Servicing the modulator now is too late as the damage is already done.

My personal advice is to get the trans rebuilt (assuming the car is worth it) or pick up a rebuilt trans & converter *across the counter* on an exchange basis & install it yourself if you can. 

Edited December 18, 2023 by 55trucker

[LokiZ34]

Thank you for all the information.

Now my question is would I be able to use 4t65HD components for the rebuild or am I still stuck with the 4t60 clutches?

Edited December 18, 2023 by LokiZ34

[55trucker]

No, you're not stuck with the 4t60 clutches at all, nowadays the rebuild kits for the 4t60 would include the latest clutch plates upgrades that can be had.

Suggest that you give Sonnax, Global Transmission parts a call or Transmission Parts USA on a 4t65 rebuild kit (assuming you want to purchase the master rebuild kit yourself).

You'll want a prior to 2002 rebuild kit, 2002-03 the valve body for the 4t65e was redesigned & improved.

Edited December 18, 2023 by 55trucker

[LokiZ34]

Thank you again ... I honestly  didn't know where to start. You have helped  lift the weight of a bus off my shoulders 

[55trucker]

Sonnax Oversized Accumulator Pin - 84573-01K

this is the part in question that wears out causing the headache...

if one was to do the work themselves this kit is what one needs, if one purchases a rebuilt trans this issue should be taken care of

[LokiZ34]

This is a discontinued part not avaliable from the mfg... this is getting  more and more hopeless lol 

[55trucker]

LOL...don't give up so quickly,

the oversized pin is a common item,

the reamer   84573-02K which is used to bore the centre of the piston is discontinued but a 3/8" drill bit that has had the end blunted will do the job (one makes use of a drill press to do this work)