clunking when it downshifts

[TIMS87GN]

Hey guys, I got my tranny rebuilt right before the Nationals. Great job with it too. Nice and firm and no slippage. I haven't talked to the builder yet but....

Ever since we put it in it clunks during downshifts at low speed. Sounds just like the noise it makes when it is put in gear. You know the sound, bad u-joint. It has a new tranny mount and u-joints are fine. So what could it be?
The noise is getting on my nerves now and I'm sure it sounds great to people standing around when I drive by.

Any ideas, or adjustments maybe?

Thanks.

 

[Otto J]

Does it only happen when it goes from 3-2 while slowing down?

 

[turbojimmy]

Mine's done that ever since I put my Level10-built trans in it. Works great but downshifts from 3-2 are harsh. I'd get a clunk and could hear the driveshaft ringing. I put new U-joints in it a few weeks ago and that's taken care of most of it. Still harsh but feels/sounds tighter. Plus, the U-joints appeared to be original - figured 100k was enough for them.

Jim

 

[Otto J]

DO you have billet servos in these trannies? If so that is the culprit of teh 3-2 downshift clunk, Contact Chris at CK he has the GM early 200 servos which are just as big but give a better 2-3 and no clunk on the 3-2 shifts

 

[turbojimmy]

Originally posted by KLHAMMETT
DO you have billet servos in these trannies? If so that is the culprit of teh 3-2 downshift clunk, Contact Chris at CK he has the GM early 200 servos which are just as big but give a better 2-3 and no clunk on the 3-2 shifts

Yes mine has a billet servo. It doesn't really bother me enough to mess with it. If (when?) I have it out again I'll look into it.

Thanks.

Jim

 

[Otto J]

Billet servos are notorious for the 3-2 bang, Change it out, I believe Chris get around 55bucks for the good one

 

[GNTOIT]

I have same problem. How do I know if my UJoints are bad? I know my tranny mounts are.

 

[chris718]

hammet is correct .it is a rough band apply when the valvwe body backshifts.at closed throttle there is no cushion for the back shifting with that servo due to poor engineering and removal of the cushion spring.what were they thinking?

 

[Phatman]

I went back to the stocker and it made quite a difference in the 3/2 shift. Still a little rougher than I'd like, but when the car sits in the shop a year at a pop I can live with it.....

 

[TIMS87GN]

Thanks for the response guys. I admit, I should replace the u-joints and will get around to it. So it is the billet servo? I thought that was the big deal to have the billet servo? So its not? Sheesh! I was just imagining damage being done every time I hear it. I was having visions of tiny metal fragments circulating through my new trans.

As little as I drive it, if its not damaging anything, I can live with it.

Thanks guys!

 

[chris718]

a wise man once said a penny saved is a penny earned.

 

[HellOnWheels]

Chris,

What size are the "early" servos that help to eliminate the harsh 3-2 downshift? Guess that could be my problem as it "bangs" pretty hard on the downshift.

TIA
HOW

 

[chris718]

before spending any mony reinstall the cushion springs and road test.

 

[87GN_70GS]

Increasing the servo endplay (shorten the pin) will reduce the clunk, but also slow the band apply.

 

[d0n_3d]

my tranny with about 500 highway miles on it from Vince Janis downshifts hard on the 3-2 also and you can hear a clank or clunk or whatever you call it...figured it was just part of the shift kit that he does...I have just a billet forward drum...not sure what else he does to the trannies...it was a street performance rebuild...