Transmission "Bump" at stop
 

Fellas,

After I put in a new crate 350 about 3K miles ago, I've noticed something little odd with the transmission - which is a TH350 auto with the standard 3 on the tree for a 64.

It shifts fine and smooth, kick-down is perfect - but sometimes when I get to a stoplight, I feel a very slight bump - like it's "resetting" into 1st gear - after it's already dropped to 1st.

Performance is great, fluid level is good - it's just a new thang. I'm curious if this is a sign of bad things to come, torque converter related (?), or the classic "Nothing to see here...".

Any thoughts/comments appreciated - as always.

Re: Transmission "Bump" at stop
 

Couple of things to check:

Vacuum modulator hoses are in good condition and vacuum port in manifold is not clogged...

Engine idle speed a tad too high

Trans fluid a little low...how long since trans filter and fluid was changed?

I doubt the convertor is an issue....

:chevy::chevy::chevy:

Re: Transmission "Bump" at stop
 

Driveline/driveshaft bind up like that's has been so common in modern trucks?

Re: Transmission "Bump" at stop
 

Three on the tree is a 3 speed manual shift on the steering column. It is not a automatic transmission

Re: Transmission "Bump" at stop
 

Kind of confusing... but I'm guessing you have an automatic.

Check to see if the torque converter bolts are tight at the flex plate.

Gary

Re: Transmission "Bump" at stop
 

What carb?
Maybe fuel level isn’t ‘great’ once in awhile. Could be A very slight bit of sloshed fuel. Gives a little surge.
What distributor?
Weights could be hanging up.
And is vac advance hooked to ported or manifold vacuum port?

Re: Transmission "Bump" at stop
 

Yeah, automatic. Don't know why I keep thinking that...sounds pretty cool though, right?

Re: Transmission "Bump" at stop
 

Might double check the motor and trans mounts for tightness. Several hundred pounds of engine/trans settling back into place can often be felt.

Also check the bolts holding the engine/trans together plus the bolts on the flex plate.

Something loose/worn in the rear end/spring shackles?

Re: Transmission "Bump" at stop
 

Like has been suggested I would remove the driveshafts and check out the U joints.