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The dealer replaced my transmission and claims the driveshaft is worn out
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? |
It's plausible, although not a certainty.
If it's under warranty, why not? |
Assuming it's a warranty claim, let 'em do it. If the sound is still there, then it's BS, and the dealer has more work to do. If not, problem solved.
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I guess there's no harm, as it is under warranty. But I have very little confidence in the people doing the work. Therefore I want them touching the car as little as possible. It seems to me it is more likely the transmission replacement was not done properly and that is the real cause of this new noise.
Maybe the mechanic damaged the shaft when mating it with the tranny, or it just wasn't in all the way. [insert "is it in yet?" joke here] |
I agree with your theory of them damaging it. Driveshafts and transmissions are interchangeable; they don't come as a matched set. And if the u-joints on the driveshaft were wearing out, you'd have heard it with the old transmission too. They didn't magically develop increased wear to the point of making noise just because the driveshaft was removed and reinstalled.
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Is it a sound or a vibration?
I haven't looked under these cars yet, are they a 2-piece driveshaft with a Center Support Bearing? Perhaps he just pulled the front half to do the trans and installed the front half clocked wrong and now it's out of balance. *From the old BMW days* |
Is it at engine speed, or road speed? Ie, if you throw the car in neutral does it go away? Or if you have it in neutral and rev the engine does the sound change?
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I only hear it in first gear soon after the clutch is released. At dealer now waiting for them to pull the car around.
I believe it is a sound caused by a vibration. |
If the dealers theory about wearing out together then why didn't he replace the driveshaft also? Id tell him to put in a new driveshaft if it's under warranty, if not they may have just installed the driveshaft out of phase if it's a slip joint driveshaft or the u-joints are bad or even possibly it just needs to be balanced.
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They put in a new driveshaft, looked at it multiple times and the noise is still there. Going to have another dealer look at it tomorrow.
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Then maybe the noise is being caused by the new transmission. Maybe they installed it wrong (shift linkage goes up!) or maybe it had issues before they put it in.
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New shaft, and the plot thickens, geez.
You did a great job clearing up the drama and just stating the raw facts, Pat. Nice job! lol I was under the impression these transmissions were simply replaced with new units, it takes more time and expense to pay a tech to rebuild it and replace individual parts. If this is untrue, then please let me know. This also makes me wonder, if instead of receiving new transmissions, if we're actually getting transmissions rebuilt at some factory service center. They get pulled apart, inspected, "repaired", and rebuilt. Just my own personal suspicion, but it would explain why a "new" tranny is noisy. Unless a bearing or something was somehow damaged during install. If the sound comes from/after clutch action, could it possibly be clutch related? Quote:
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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. |
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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. |
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. |
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. |
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 |
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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. |
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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. |
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 :) |
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The engine is bogging because of the load at that RPM... |
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LoL Evo owners |
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