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4T65E "Clunk" when re-engaging from a roll

S

spencertimm

New member
Hi all,

I am new to the forums, and I am not actually a Grand Prix owner (I have a 2006 Buick Rendezvous), but the people on this forum seem to be much more knowledgeable than those on the Buick forum.

Anyway, I have been having a couple issues with the transmission in my vehicle, but I installed a Trans-Go shift kit that seemed to do some good. However, for a while I have had this issue (not yet sure if it is an issue or not) where the transmission clunks back into engagement after I let off the throttle and get back on it at low speeds, i.e. slowing down approaching a red light and then the light turns green and I am back on the throttle.

Is this normal? Or is something amiss here?

Thanks!
 


How many miles? Sounds like the input clutch piston issue, that will require a full rebuild to fix. It usually starts off as feeling a little bump on takeoff, like it wasn't fully engaged at first. Then over time it gets worse as it seems it's completely in neutral til you give it gas. This seems to be a common thing lately. Every time I see it, it's on a 03+ 4t65e or an impala of 00-05, although I don't know of any changes in that particular area of the transmission.

You can try adding like half a bottle of lucas transmission stop slip, thickens up the fluid a bit (and does things to the seals) and should lower the amount of leakdown on the input clutch piston sealing area. Eventually it will get worse unfortunately.

Does the way I described it sound like your case? If it's just a clunk noise and that's it, check your motor and transmission mounts as they might be pretty loose. Have someone shift from reverse to drive and watch the engine for excessive movement.
 
It has almost 127,000 miles on it. It does sound like that, although that bump on takeoff happens very infrequently, but it does happen. I just had a motor mount replaced about 7 months ago and they just tightened up the engine and subframe mounts about 2 weeks ago.
 
Yeah, it seems like the transmission issue I was talking about then. Our impala does it pretty infrequently as well, but it's noticeable. It will get worse unfortunately. I don't usually drive it but the few times I do, it happens at least twice on every drive I go for. It hasn't done a complete neutral start yet.
 
So does that mean that it needs to be rebuilt immediately? Or do I have a little bit of time? I have a couple trips planned to go down to California (each about 1,000 miles round trip) and one up to Seattle within the next month. Do you think I'm safe taking those before I have the work done? I am just not sure I will have time to get it in. Thanks for all the info! Nobody has ever understood so well what I was describing.
 
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