The dealer replaced my transmission and claims the driveshaft is worn out

[wheelhaus]

Originally Posted by Pat

I was told the tranny was new. I have no reason to believe otherwise, but who knows?
It could be clutch related, but the feel makes me think it is driveshaft related. I'm no pro, so I could very well be wrong.
It seems to me as if the driveshaft rotating at a certain speed is what causes the issue. Perhaps it is not balanced properly. That seems like the simplest explanation.

Well if only one part was changed, I'd first suspect that part, in this case it's the transmission. I don't understand how the driveshaft would suddenly start vibrating after simply being removed and reinstalled, unless it was dropped on the floor and was bent when the new tranny was installed. If that were the case, then the new shaft would have eliminated it.

Beside that, you could test the clutch when the vibes are present. Try killing the engine and coasting, both clutch disengaged and in gear, as well as clutch engaged and in gear neutral. These three steps would verify or eliminate the clutch if the vibes stop or persist at any point.

[Pat]

Thanks, wheelhaus. I just drove the car and turned the engine off while coasting:
1. with shifter in neutral and clutch engaged
2. with shifter in gear and clutch disengaged
Nothing felt unusual with either one.
The only time I can get it to vibrate is with the car in gear and engine running while there is load on the drivetrain at low RPM (~1,500). I was able to replicate this in 1st, 2nd and 3rd. I have not tried other gears.

[Wayno]

Any time the wheels are spinning, the drive shafts and tail shaft are also spinning.

So if it's fine in gear with the clutch in, sounds like something wrong with the clutch.

[celek]

Go test drive a brand new 86. If I recall 0 miles has a slight whine like a supercharger to it but then again its been 3 years. After a few 1000 miles it gets quieter as its broken in.

Sound clip would help

[wheelhaus]

Originally Posted by Pat

Thanks, wheelhaus. I just drove the car and turned the engine off while coasting:
1. with shifter in neutral and clutch engaged
2. with shifter in gear and clutch disengaged
Nothing felt unusual with either one.
The only time I can get it to vibrate is with the car in gear and engine running while there is load on the drivetrain at low RPM (~1,500). I was able to replicate this in 1st, 2nd and 3rd. I have not tried other gears.

Originally Posted by Wayno

Any time the wheels are spinning, the drive shafts and tail shaft are also spinning.

So if it's fine in gear with the clutch in, sounds like something wrong with the clutch.

Wayno is correct, anytime the wheels are rolling, the driveshaft (and the output half of the transmission) is spinning as well regardless of gear selection or clutch. So if the driveshaft were causing a vibe, it should be present regardless of engine activity. The only thing on the shaft affected under load would be support bearings or u-joint bearings, but they'd sound like grinding, growling, screeching, or they'd feel like they were filled with rocks and apples more than just a resonant vibe.. And the grind would change with speed.

That points to something ahead of the tranny. The "under load" is the only thing that's strange. I wonder if they loosened the engine mounts to remove the tranny and left one mount loose, and the vibe you're feeling under load is caused by lugging the engine a bit (1500rpm-ish) because everything is allowed to move a little more than it should. Might not be detectable from freely revving the engine because there's no load.

I'm curious to hear what the 2nd opinion is.

[venturaII]

Originally Posted by gramicci101

I would put money on this being the case. It's more cost effective for the manufacturer.

I had second gear synchros let go in a different car with just ~20K miles on it. Instead of replacing with a new or even factory reman unit, the dealership rebuilt the transmission, much to my displeasure, at the direction of the manufacturer. The transmission stayed together just long enough to clear the powertrain warranty, and then the same problem appeared.

[Scott@HKSUSA]

I think every manufacturer and every transmission is different.

Honda rebuilt my Civic Si trans after I took it back for a consistent 3rd gear grind. Turned out to be a bent shift fork from (I presume) a previous test driver.

Nissan replaces suspect GT-R transmissions with complete factory rebuilt units they keep stocked in the US.

And Mitsubishi doesn't take care of anything so Evo owners rebuild their own

[Poodles]

Originally Posted by Pat

Thanks, wheelhaus. I just drove the car and turned the engine off while coasting:
1. with shifter in neutral and clutch engaged
2. with shifter in gear and clutch disengaged
Nothing felt unusual with either one.
The only time I can get it to vibrate is with the car in gear and engine running while there is load on the drivetrain at low RPM (~1,500). I was able to replicate this in 1st, 2nd and 3rd. I have not tried other gears.

The engine is bogging because of the load at that RPM...

[Sammakko]

Originally Posted by Pat

The dealer recently replaced my transmission due to grinding during the 3 to 4 shift at redline. When I picked up the car with the new transmission there was a noise in the drivetrain related to load and speed. This noise was not present before the transmission was replaced. When I told the dealer about it they said the driveshaft now needs to be replaced. They claim the original transmission mated with the original driveshaft in such a way that they wore out together. Therefore, when the new transmission was installed, it didn't mate with the original driveshaft as it should. Because of this, I now need a new driveshaft, too.
Does this make sense to you guys? I've never heard of this happening, and wonder if the mechanic that did the work just wasn't careful and damaged my original driveshaft.
Thoughts?

i was a driveline tech for 3 years, the dealer is feeding you a total line of bullshit.

[chaoskaze]

Originally Posted by Scott@HKSUSA

I think every manufacturer and every transmission is different.

Honda rebuilt my Civic Si trans after I took it back for a consistent 3rd gear grind. Turned out to be a bent shift fork from (I presume) a previous test driver.

Nissan replaces suspect GT-R transmissions with complete factory rebuilt units they keep stocked in the US.

And Mitsubishi doesn't take care of anything so Evo owners rebuild their own

LoL Evo owners