# Is an auto tranny shift kit supposed to "clunk" into the next gear? THUD! **URL:** \ **Category:** General Discussion\ **Created:** [September 16, 2014, 5:51am UTC](https://community.cartalk.com/t/is-an-auto-tranny-shift-kit-supposed-to-clunk-into-the-next-gear-thud/87208 "2014-09-16T05:51:01Z")\ **Posts on this page:** 14\ **Page:** 1
**Author:** ![UsedEconobox\_2\_UsedBMW](https://avatars.discourse-cdn.com/v4/letter/u/8491ac/32.png) [@UsedEconobox\_2\_UsedBMW](https://community.cartalk.com/u/UsedEconobox_2_UsedBMW)\ **Post date:** [September 16, 2014, 5:51am UTC](https://community.cartalk.com/t/is-an-auto-tranny-shift-kit-supposed-to-clunk-into-the-next-gear-thud/87208/1 "2014-09-16T05:51:01Z")
Friend has one of these. When it shifts, there is a loud jarring THUD. Is that what its supposed to do? ---
**Author:** ![Caddyman](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/caddyman/32/23_2.png) [@Caddyman](https://community.cartalk.com/u/Caddyman)\ **Post date:** [September 16, 2014, 6:33am UTC](https://community.cartalk.com/t/is-an-auto-tranny-shift-kit-supposed-to-clunk-into-the-next-gear-thud/87208/2 "2014-09-16T06:33:26Z")
Read the box it came in to see what it’s supposed to do…If it promises “Firm, solid shifts” then that’s what it’s doing…But they forgot to tell you, at low throttle settings, the hard shifts can be very annoying… ---
**Author:** ![wesw](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/wesw/32/2713_2.png) [@wesw](https://community.cartalk.com/u/wesw)\ **Post date:** [September 16, 2014, 6:40am UTC](https://community.cartalk.com/t/is-an-auto-tranny-shift-kit-supposed-to-clunk-into-the-next-gear-thud/87208/3 "2014-09-16T06:40:05Z")
so floor it man! ---
**Author:** ![Caddyman](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/caddyman/32/23_2.png) [@Caddyman](https://community.cartalk.com/u/Caddyman)\ **Post date:** [September 16, 2014, 6:46am UTC](https://community.cartalk.com/t/is-an-auto-tranny-shift-kit-supposed-to-clunk-into-the-next-gear-thud/87208/4 "2014-09-16T06:46:40Z")
Yeah! Get some satisfying second gear scratch! ---
**Author:** ![UsedEconobox\_2\_UsedBMW](https://avatars.discourse-cdn.com/v4/letter/u/8491ac/32.png) [@UsedEconobox\_2\_UsedBMW](https://community.cartalk.com/u/UsedEconobox_2_UsedBMW)\ **Post date:** [September 16, 2014, 7:13am UTC](https://community.cartalk.com/t/is-an-auto-tranny-shift-kit-supposed-to-clunk-into-the-next-gear-thud/87208/5 "2014-09-16T07:13:15Z")
Friend bought it like that. No box. ---
**Author:** ![the\_same\_mountainbike](https://avatars.discourse-cdn.com/v4/letter/t/c89c15/32.png) [@the\_same\_mountainbike](https://community.cartalk.com/u/the_same_mountainbike)\ **Post date:** [September 16, 2014, 8:20am UTC](https://community.cartalk.com/t/is-an-auto-tranny-shift-kit-supposed-to-clunk-into-the-next-gear-thud/87208/6 "2014-09-16T08:20:07Z")
I suggest that you not take automotive advice from your friend. No, that is probably not supposed to happen, but if one puts unknown secondhand stuff on one’s car, one gets what one gets. So, now, does your friend know why he probably got this thing secondhand for such a great price? ---
**Author:** ![Cavell](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/cavell/32/43396_2.png) [@Cavell](https://community.cartalk.com/u/Cavell)\ **Post date:** [September 16, 2014, 5:24pm UTC](https://community.cartalk.com/t/is-an-auto-tranny-shift-kit-supposed-to-clunk-into-the-next-gear-thud/87208/7 "2014-09-16T17:24:40Z")
Describe car. Year, model. ---
**Author:** ![circuitsmith](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/circuitsmith/32/40376_2.png) [@circuitsmith](https://community.cartalk.com/u/circuitsmith)\ **Post date:** [September 16, 2014, 7:23pm UTC](https://community.cartalk.com/t/is-an-auto-tranny-shift-kit-supposed-to-clunk-into-the-next-gear-thud/87208/8 "2014-09-16T19:23:38Z")
This is the downside of setting up a street car with racing stuff. ---
**Author:** ![the\_same\_mountainbike](https://avatars.discourse-cdn.com/v4/letter/t/c89c15/32.png) [@the\_same\_mountainbike](https://community.cartalk.com/u/the_same_mountainbike)\ **Post date:** [September 16, 2014, 7:31pm UTC](https://community.cartalk.com/t/is-an-auto-tranny-shift-kit-supposed-to-clunk-into-the-next-gear-thud/87208/9 "2014-09-16T19:31:08Z")
And used racing stuff of unknown history at that… ---
**Author:** ![researcher](https://avatars.discourse-cdn.com/v4/letter/r/edb3f5/32.png) [@researcher](https://community.cartalk.com/u/researcher)\ **Post date:** [September 16, 2014, 10:19pm UTC](https://community.cartalk.com/t/is-an-auto-tranny-shift-kit-supposed-to-clunk-into-the-next-gear-thud/87208/10 "2014-09-16T22:19:49Z")
I think what the OP is saying is that the shift kit was in the trans at the time of the purchase of the car. You might go back to the seller and see if the original parts were kept. Shift kits usually involve stiffer accumulator springs, blocked accumulator passages, altered valve body plates, removal of select passage balls, etc. So for the price of a few gaskets the original kit can be reinstalled. ---
**Author:** ![ken\_green](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/ken_green/32/816_2.png) [@ken\_green](https://community.cartalk.com/u/ken_green)\ **Post date:** [September 17, 2014, 1:54am UTC](https://community.cartalk.com/t/is-an-auto-tranny-shift-kit-supposed-to-clunk-into-the-next-gear-thud/87208/11 "2014-09-17T01:54:00Z")
Here’s the answer to smooth shifts. put a 27’ trailer on it ! My79 shifts…uhm…’‘decisevely’’ unless you load it up. Then it shifts as smooth as glass. 27’ trailer, pallet of pellets, bed full of sod. ---
**Author:** ![UsedEconobox\_2\_UsedBMW](https://avatars.discourse-cdn.com/v4/letter/u/8491ac/32.png) [@UsedEconobox\_2\_UsedBMW](https://community.cartalk.com/u/UsedEconobox_2_UsedBMW)\ **Post date:** [September 17, 2014, 5:40am UTC](https://community.cartalk.com/t/is-an-auto-tranny-shift-kit-supposed-to-clunk-into-the-next-gear-thud/87208/12 "2014-09-17T05:40:26Z")
Ok, let me ask the question again, b/c I don’t think I was clear. When a car like a 1990s Firebird has an AUTO TRANNY SHIFT KIT installed, is it supposed to THUD into the next gear? Yes or no? Thanks! ---
**Author:** ![keith](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/keith/32/5518_2.png) [@keith](https://community.cartalk.com/u/keith)\ **Post date:** [September 17, 2014, 6:11am UTC](https://community.cartalk.com/t/is-an-auto-tranny-shift-kit-supposed-to-clunk-into-the-next-gear-thud/87208/13 "2014-09-17T06:11:14Z")
A shift kit does provide firm shifts, enough to chirp the tires sometimes. The hard shifts do take their toll on the drivetrain, especially U joints. You could have a bad U joint or driveshaft bearing causing the loud thud. It could also be a loose gearset in the differential. ---
**Author:** ![ok4450](https://avatars.discourse-cdn.com/v4/letter/o/e9bcb4/32.png) [@ok4450](https://community.cartalk.com/u/ok4450)\ **Post date:** [September 17, 2014, 6:18am UTC](https://community.cartalk.com/t/is-an-auto-tranny-shift-kit-supposed-to-clunk-into-the-next-gear-thud/87208/14 "2014-09-17T06:18:11Z")
There are different types of shift kits. Some are mild and meant for the ho-hum daily drivers. The high performance kits are for those who race (street or strip) and want those gears banging with driver comfort not a factor. So yes, a shift kit can cause a firm/harsh/thud shift but so can an internal transmission fault or a broken transmission mount. What year Firebird? I seem to remember a transmission hard shifting bulletin about Camaros/Firebirds of the 90s era. Thinking it was 96 up; just not sure.