red-y

After rebuild I have a klunk from 3rd to 2nd gear only when the car is in D. This does not happen when down shifting from OD. What's wrong?
Help is appreciated.. :confused:

JCAIRE2

Didn't quite understand the symptom you describe. If you have the car in D, and jump on the gas while cruising in 3rd gear, you get a clunk on downshift. If cruising in 3rd gear while the stick is in OD, you do not get a clunk. Is this correct?

I have no idea what the solution would be, just making sure I understand what the problem is.

J :seeya :steering: :steering:

vader86

If youre sure this clunk is coming from the transmission, then it sounds like whoever did the rebuild didnt do a good job.

BBA

Sounds like a bad 2-4 servo piston seal or incorrecct band clearance ( too loose will cause it ). If the 3-4 and 4-3 shift is nice, it is only the servo part used for 2nd gear. You should probably notice a hard 1-2 shift as well.


Something wrong in the trans. Take it back.


[Modified by BBA, 11:54 PM 1/2/2003]

red-y

Thanks for your response - the klunk is when the car is slowing down and down shifting from 3rd to 2nd.
Not when accelerating from 2nd to 3rd. :confused:

robertpel9

my 91 does the same exact thing only when going from 2nd to 1st, not 3rd to second. It also only does it in D and not OD. It did this before the rebulid and after the rebuild. I posted something a while back on it and many others said that theirs did too. Strange indeed. I don't even think about it anymore. If your is only after rebuild and it never did it before i would take it back to the shop.

TrplBlk01

I had my rebuilt ad it still does it.
Let us know what the tranny shop says.

red-y

[QUOTE]Sounds like a bad 2-4 servo piston seal or incorrecct band clearance ( too loose will cause it ). If the 3-4 and 4-3 shift is nice, it is only the servo part used for 2nd gear. You should probably notice a hard 1-2 shift as well.


Something wrong in the trans. Take it back.

Response:
I am taking it back next week, thanks for the input. I will post the results.
:seeya

satyr7777

My Suburban did something similar after it's rebuild #2. It blew itself apart on the freeway, dumped tranny fluid on 281 North- and got me into the apartment complex parking lot in first gear doing about 5 mph at 3500 rpm. I'd take it back, and knowing what I know now I'd call around for 2 or 3 days to get quotes on prices and warranties before trusting a tranny rebuild to anyone.

red-y

RESPONSE:
ME TOO !

FD2BLK

If it only does it in D and not 3rd it sounds to me like your TC is staying locked up http://www.700r4.com Im not an expet but contact this guy I think he is the best thier is with GM OD transmisions he is great he has helped me several times.

woodstock

Has anyone experience with these guys http://www.transmissioncenter.net .
My original tranny was replaced with a high altitude trans. and got to go. I’m looking for a new tranny after ’87, open for any
suggestions!

BBA

Not true. The ecm will lock the converter in 2nd, 3rd and 4th. The ecm has no input as to what the gear range selector is as far as l1-OD.

Now...if he had a failed converter, he would have no lockup at all. If the TCC switch was failed, it would stay locked and not unlock until he slows to drop into 1st gear, most noticeable by a lugg-lugg-lugg feeling in the car when slowing to a stop light.

hngacurv

:iagree: It might not sound good, but several people say they have the same clunk, including me.

383LPE

FYI to future tranny shoppers. I found it cheaper and more reliable to buy a "new" rebuild for 1400 and install it than chase around tranny hackers and take a chance on a good rebuild. GM performance parts sells the Hughes performance tranny. They will ship it to your or installers door.

TA

My '91 clunks as well and it also does this only on the 2-1 dowshift when in "D". It did it before the rebuild and it still does it after the rebuild. There have been many threads on it here on the forum and it seems to be a fairly common on C4s of this year (possibly '89 and '90 as well?) so I'm not overly concerned with it.

If yours only did after the rebuild, though, I'd take it back to the shop. :yesnod:


[Modified by TA, 2:40 PM 1/5/2003]

Sharky Guam

Yes, you guys are correct, it is common on the 700r4 to have this symptom. But it should not do that. Take it back and have your trans shop diagnose it. There are a number of things that could cause it to do that. And over time, it could cause the trans to fail.

:seeya

robertpel9

personally i think the noise may not come from the tranny at all but rather the rear end. Mine did this before and after rebuild and the rebuild was done right. The symptom is exactly the same. My old 84 did something similar too. I dont know what do you all think??

BBA

When I have a transmission that clunks...I know what the cause is and I fix it.

Loose clutch packs and/or old hardened or damaged clutch piston seals cause this. Basically, the chain of events in a normal transmission is the pressure is applied to a clutch piston through orifices and valves and is softened by an accumulator piston. In the case of worn clutches of bad seals, the piston either does not start to move ( in the case of seal problems )or the slack in movement ( in the case of incorrect clutch pack/band play) is not taken up in synch with the slow pressure rising of the fluid to the clutch piston, with the result that when the clutch is starting to apply, full holding pressure, not the slow controlled accumulated pressure, causes the clutch element to 'BANG' into the shift. This is the clunk most complain about and can be lived with for long periods of time in some cases. It IS NOT normal acceptable performance.

BTW: I wuz a tranz xpert at 1 time.
:steering:

Slalom4me

You know, I bet this is the most reasonable advice I've seen all day. I'm currently thinking about transmission repairs - thanks.

Here is a link to the GM Performance Parts site,
http://www.gmgoodwrench.com/html/par...erfparts.shtml