Shift clunks to 3rd gear

[Mark1972]

So got the 3.55's in with the new Yukon DuraGrip. I picked it up yesterday. The shop told me to do three heat cycles with the car to break in the rear end. Drive the car normally, with no hard acceleration 15-20 minutes on, 30 minutes off, three times. Then they said drive for about 500 miles, and then drain the oil and replace. But, while driving the car the shift from 2nd to 3rd would make a "clunk" noise and feel, even though the 1st to 2nd shift was fine. I'm not sure else how to describe it. The shop was already closed when I drove it home. Can anyone offer any thoughts on what it could be? The driveshaft is new. The 727 is totally rebuilt. I'd love to drive the car this weekend but don't want to damage anything. The shop test drove it before they called me to come get it. They certainly would have felt it. Just a little nervous is all. Thanks guys.

 

[Bad B-rad]

It could be band adjustment for 2nd gear if not adjusted properly will either cause slip or harsh engagement.
Easy to do, but it should have been done by trans shop.

 

[turbine68rt]

Did you have a shift kit installed during the rebuild such as a TF-2?

 

[furious70]

First time driving the trans too? With shift kits and easy driving TF's often bang into 3rd

 

[idrivemopar]

Its shift overlap. Happens with shift kits. I have the same issue, and its because i had a kit, then rebuilt without the kit, so at low speeds its clunky, but when i stand on it, it shifts tight.

 

[dvw]

Shift overlap. KD band releases slower than the high/rev clutch applies. On heavy acceleration th e trans will shift well and prevent flare on the 2/3 shift. At slow speed it actually locks the trans in 2nd and 3rd at the same time. This is the clunk you feel. Really no big deal.
Doug

 

[Ron H]

I installed a kit some 15 years ago on my '63 727 set it to a medium shift and the 3rd up shift engagement is like what is being posted here, don't really like it; but is what it is.

 

[Ron H]

To add, if this is a concern, take it to your shop to have them drive it and let us know what they say...

 

[toolmanmike]

My Swinger does that when driving it easy. I adjusted the bands and tightened up the kickdown when I serviced it. It doesn't do it if I manually shift it or if I stand on it like you guys said.

 

[Bighead440]

Shift overlap. KD band releases slower than the high/rev clutch applies. On heavy acceleration th e trans will shift well and prevent flare on the 2/3 shift. At slow speed it actually locks the trans in 2nd and 3rd at the same time. This is the clunk you feel. Really no big deal.
Doug

Using a rigid band (relined original 60s band core), a early servo (no inner piston O-ring type), and keeping .090-.110" front clutch clearance with a flat snap ring seems to work well for me. 9 clutch piston return springs in the drum and a 3.8-4.2 max band apply lever really help as well. Too tight on the front clutch clearance, 6 return springs and a flexy kickdown band with a 5.0 lever is the worst of all worlds. LOL

 

[Mark1972]

Well after finally getting out the last two weekends and stretching her legs, I now know the 2nd to 3rd gear clunk I hear during moderate city driving is a much tighter shift when you're leaning on it hard. So thank you for the responses.