Major thumping when shifting

[kegard]

I have a 96 Rodeo LS with Auto trans, and recently this thumping has been occuring when the trans shifts. Most of the time the tranny shifts smoothly and occasionaly it would thump when shifting, but now the thumping has gotten louder and is happening more often.

I did a search on this and it seems that the slip-yoke (part of the driveshaft?) sometimes needs lubrication and that will take care of it. But last time my truck was in the shop (a couple weeks ago) they said they did this for me and now it's thumping again.

First of all, is this thumping a problem with the trans or the driveshaft? I bought this vehicle a couple months ago with 120k miles on it, and the first thing I did was take it to a dealer and got the trans flushed. While they were flushing it I got to take a look at the machine as it was pulling the old fluid out and putting the new synthetic in. The mechanic told me that the fluid in the trans looked pretty good. Not very dark at all.

Now my truck is in the shop again (to get the leaf spring bushings replaced) and I'd like them to examine whatever the problem point may be. Any help would be appreciated!!

[rodeo02]

Could be a worn universal joint on the rear drive shaft, a worn pilot bearing (rear drive shaft), broken spring shackle. I would suspect a suspension issue given you are getting no "check transmission" light. Hope you find it!
G/luck
Joel

[kegard]

I had the shop remove the drive shaft and regrease the slip-yoke, which seems to have solved the problem. Still a slight thump from first to second, but nothing I can't live with.

I'm going to take a close look at the U joint and the rest of the driveshaft this weekend. Thanks for the help!

[bnorth76]

Hello,

I've recently purchased an Isuzu Rodeo(1999). I am currently hearing a knocking noise when I accelerate. I am currently using 87 octane gas. Could the knocking noise when I accelerate be a result of using 87 octane gasoline? I was not getting this before I refueled using 87 octane gas. Please help.

Thanks.