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What would cause a harsh shift into reverse?


1990lumina

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Alrighty, this problem has been getting worse and worse, and finally I'm gonna post about it.

 

Car: 1990 Lumina 3.1 w/ 4T60

 

The problem: when I shift the car into reverse, when it shifts there is aquite an apparent "Clunk" and almost feels like someone has just rear ended the car.

So I'm thinking some mounts are shot somewhere, but which ones, and where are they?

 

This jolt into reverse happens no matter what gear you are shifting from.

 

The shift into drive is less severe, but it is it getting pretty rough as well.

 

Anyway, any ideas, hints, help??

 

That would be great, thanks guys for putting up with my questions :D

 

- Jeff L.

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Sounds like tranny vacuum modulator, or the vacuum line going to it is plugged. When I completely plugged the line on my 88 GP it was extremely hard shifting into reverse if the car was moving at all, upshifting was very firm, downshifting felt like the tranny wanted to jump out of the car.

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Werd C-BAD....exactly what I'm experiencing. The shifts while increasing speeds is nice a firm, but if Ipunch it, sometimes there will be a "thunk" as it downshifts...

 

Same thing will happen if I have it WOT while accelerating. When it shifts into 3rd from 2nd there is a "thunk".

 

I'll have to check that modulator thing. I still have that PM I sent me C-BAD, just haven't had time to check things lately :(

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Actually, on my Lumina (same year and setup) the bushing inside my dogbone was completely shot. Put a new dogbone on and I was good to go. It would "clunk" as I was shifting it through any gear or if I would use any torque in accelerating.

 

Check out what C-Bad was talking about, I've heard of that happening too.

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Actually, on my Lumina (same year and setup) the bushing inside my dogbone was completely shot. Put a new dogbone on and I was good to go. It would "clunk" as I was shifting it through any gear or if I would use any torque in accelerating.

 

Check out what C-Bad was talking about, I've heard of that happening too.

 

I had that thunk and a metalic noise b/c both of my dogbones were shot a while ago. You might want to check on those first. If I remember correctly they cost $20 a piece at NAPA. Not an expensive repair if you ask me.

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Actually, on my Lumina (same year and setup) the bushing inside my dogbone was completely shot. Put a new dogbone on and I was good to go. It would "clunk" as I was shifting it through any gear or if I would use any torque in accelerating.

 

Check out what C-Bad was talking about, I've heard of that happening too.

 

I had that thunk and a metalic noise b/c both of my dogbones were shot a while ago. You might want to check on those first. If I remember correctly they cost $20 a piece at NAPA. Not an expensive repair if you ask me.

 

 

yes thats what mine cost. between 15-25 bucks at advance auto

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Well if the dog bones are shot I'll replace them with FFP ones since ppl seem to recommend them.

 

I'll check these items tomorrow when I have time.

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