Loud Clunk During Downshifts

[SYTECH]

I had my 2004r rebuilt last week by a local Socal Shop (CPT in H.B).

My 87 GN was running low 12's (12.2 @ 113 mph)110 octane fuel, 24 lbs boost, TA-49, 009's before the tranny shifts started acting up (started flairing / slipping)

Tranny was given a Hi-Performance re-build along with a 9inch non-L/U torque convertor (3200 stall)

I have had the car back for 4 days and have driven it about 200 miles (street / highway - no track yet)

Up-shifts feel good but when coasting or decelerating to a slower speed, the tranny has a definate clunk as it engages the lower gears

It only happens with light to no throtttle application

Tranny temp is 150 - 175 (hot). Tranny cooler is a large Hayden unit.

I have had the car for 1 year and I have never felt this clunk before. It seems loud enough that a car along side of me will hear it if he has his window down

Is this normal?

Is the non-L/U stall convertor adding to this ?

Billet Servo?

Can high line pressures cause this ?

I have changed the driveshaft & universals in the past 3 months, but other than servicing the Auburn posi, the differential is stock

Any advice would be appreciated before I take the car back to the shop

Thanks

Ray

 

[Kevin Turch]

Mine does that also, ive gotten used to it as being normal.

 

[ITSAV6]

clunk

Was valve body modified for firmer shifts? Some shift kits have this "feature". My tranny used to do this when in D but not in OD.

 

[SYTECH]

Billet Servo

Seems the kind folks at CPT (Art Carr's new Group) had installed a billet servo thinking I was going for big HP (600 plus)

Art Carr himself knew what was up the minute I spoke to him

His guys switched out the Billet Servo and vila...the clunking is gone

Took less than 1 hr

Most of the time was letting the car cool down before the popped off the servo cover, and fixed me right up

Thanks for the advice everyone

Later

Ray