a306

hey everuone

when driving my 4+3 today I let off the gas completely at around 3 grand and when it fell to 2.6 it made a grinding noise. I tried in every gear and same result about same rpm. What could be causing this? Completely stock 86

a306

Just a quick bump. Still does the noise, if I come off the gas at four grand and let it rev down there’s only noise in that rpm. I also have a weird whining noise you can only hear in the passenger compartment in third gear. Going to try a transmission fluid change

billschroeder5842

Noises are very hard to diagnose on the boards without video. One mans "Whine" is another mans squeal."

It would really help if you added more detail. Noise on deceleration only? What happens if you shift to neutral at 4k and let the rpms wind down natural?

What happens if you drive the car steady at 2600 rpms?

maxxhawk96CE

Does it grind at 2600 in neutral not moving? Does it go way when you push the clutch in? If it grinds sitting still you could pop the hood and let someone bring the RPM's up and listen to see where it's coming from.

a306

good point about the video. I have uploaded one here:
this sound will will only occur when decelerating in any gear including od. In the video I believe I stayed in first, got it up to three grand and “engine brakes” down. You can here it make noise around 2900-2800 and go away

the sound does not happen in neutral, and goes away if I push clutch in. This same noise happens at low rpms in reverse as well I found out. I could make it happen consistently by having the wheel all the way to one side and going in reverse. It feels like anytime it’s under a load it does it

however, nothing above and below that 2800 mark makes zero noise when decelerating

billschroeder5842

Huh, I'd say it sounds a bit like a dual mass fly wheel disengaging but I don't think you have one of those.

This sounds trans related to em Sorry, I can't help you with a 4+3...

maxxhawk96CE

Okay. I have not had this happen to me, but I do like a good mystery. My car has the 6-speed in it, so I have no knowledge of the overdrive unit. That being said, this is what I would do if I were you.

Two more questions, one does vibration seem to be less noticeable when it is 4th gear? Can you feel the vibration in the shifter when it is doing it?

I would lift the rear of the car in the air and start checking the u joints for play and slop. I would check the transmission, rearend and torque arm mounts to make sure that they are not loose, worn, broken or moving. Turn the tires by hand with the transmission in neutral and with it in gear and the clutch in and listen and feel for any strange sounds or vibrations.

To me it sounds like something is rubbing something that it's not supposed to be. I would drain the fluid in the transmission and the overdrive unit. Check the fluid for metal shavings or other contaminants. If your unsure about what your looking for take it to a mechanic or shop that you trust and let them do it. The T 10 is a good transmission, but they can have problems. If nothing else you'll know the trans fluid has been changed. Again I have no experience with that overdrive unit.

With the things you have said and the video, I would be looking at the transmission because it's the main thing that is married to the engine and is partially effected by RPMs. Now it could be many other things, like I fixed a car once that it would grind like that when the guy hit the brakes and the starter gear would slide forward and touch the flex plate because a spring in the starter broke.

There is my two cents.