Auto box or is it.

[BlackWidow]

Guys,

This one is for you auto box specialists out there,.. In general my box is fine it has done 175000 miles now and has developed an odd habbit. On the Colorado it has an overdrive and when it changes from one gear to the next it uses the overdrive chambers as a cushion for the main change thus making the gear change vertually undetectable.

Mine is doing this fine but when it does the last gear change into overdrive and whilst in overdrive for a short time I get a vibration from the drive train. It is similar to having a shaft on the way out or an inbalance on the shafts.

Any one have any ideas what in the box could cause this.

Steve

 

[Jon Wildsmith]

Mine is doing this fine but when it does the last gear change into overdrive and whilst in overdrive for a short time I get a vibration from the drive train. It is similar to having a shaft on the way out or an inbalance on the shafts.

Do you mean the vibration is only there during the gear change Steve?

 

[BlackWidow]

No it does it during the lead up to gear change and after the change is complete. The gear change it self is as smooth as silk.

Steve

 

[Jon Wildsmith]

Could it be that it's at specific road speeds and you have a propshaft UJ starting to go?

 

[uHu]

Could be a bad injector, or even engine mounts.
Those are much more present when the gearbox is in lock-up.
When not in lock-up the converter cushions those vibes nicely.

Have you checked the spindle bearings? (the outer end of the front drive-shafts)

 

[BlackWidow]

Thanks for the help guys, I have been underneath the old girl and I think that I have found a spinning cup. This may mean that I have a UJ on the way out so could be the problem, I have witness marked it and will re-check in a week or so.

Steve