Grinding During Engine Braking
#1
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Car: 1984 Trans Am
Engine: 5.0
Transmission: Borg-Warner T5
Grinding During Engine Braking
Hey folks,
My 84 TA is making a grinding sound when I take my foot OFF the gas in gear; noise happens in all gears. As soon as I give it the slightest bit of throttle, it goes away. I also get the same grinding at all times in reverse. Noise seems to be coming from the transmission, am I looking at a worn clutch or stripped gearbox? I suppose it could also be a wheel bearing, but that doesn't explain why it disappears so suddenly.
Thanks for any suggestions!
My 84 TA is making a grinding sound when I take my foot OFF the gas in gear; noise happens in all gears. As soon as I give it the slightest bit of throttle, it goes away. I also get the same grinding at all times in reverse. Noise seems to be coming from the transmission, am I looking at a worn clutch or stripped gearbox? I suppose it could also be a wheel bearing, but that doesn't explain why it disappears so suddenly.
Thanks for any suggestions!
#2
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Re: Grinding During Engine Braking
Hey folks,
My 84 TA is making a grinding sound when I take my foot OFF the gas in gear; noise happens in all gears. As soon as I give it the slightest bit of throttle, it goes away. I also get the same grinding at all times in reverse. Noise seems to be coming from the transmission, am I looking at a worn clutch or stripped gearbox? I suppose it could also be a wheel bearing, but that doesn't explain why it disappears so suddenly.
Thanks for any suggestions!
My 84 TA is making a grinding sound when I take my foot OFF the gas in gear; noise happens in all gears. As soon as I give it the slightest bit of throttle, it goes away. I also get the same grinding at all times in reverse. Noise seems to be coming from the transmission, am I looking at a worn clutch or stripped gearbox? I suppose it could also be a wheel bearing, but that doesn't explain why it disappears so suddenly.
Thanks for any suggestions!
#3
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Car: 1984 Trans Am
Engine: 5.0
Transmission: Borg-Warner T5
#5
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Re: Grinding During Engine Braking
It could also be a rear end noise they tend to transmit through the torque arm.
#7
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Re: Grinding During Engine Braking
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#9
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Car: 1984 Trans Am
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#11
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Car: '86 Bird, 96 ImpalaSS, 98 C1500XCab
Engine: LG4, LT1, L31
Transmission: 700R4, 4L60E, 4L60E
Axle/Gears: 3.73 Tors, 4.88 spool, 3.73 Eaton
Re: Grinding During Engine Braking
Hold on, guys.
Throwout bearing typically makes the noise with clutch pushed in.
I'm going with Bob's original statement: pinion bearing.
Symptons are classic.
Throwout bearing typically makes the noise with clutch pushed in.
I'm going with Bob's original statement: pinion bearing.
Symptons are classic.
#12
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Car: 1984 Trans Am
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Transmission: Borg-Warner T5
Re: Grinding During Engine Braking
Thanks for the reply. I'll probably have to replace all the bearings, the car was neglected for a time and they're all in questionable shape, but cheap. What I was really worried about was stripped gears, which it sounds like it isn't.
#13
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Car: 1988 Camaro(92 Z28 clone)
Engine: Forged 383, AFR 195 419/430@wheels
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Axle/Gears: 9in Detroit locker-3.90's,35 spline
Re: Grinding During Engine Braking
You can observe this by watching the crank pulley or harmonic balancer while someone revs up the car or engages/disengages the clutch. If the crank moves too far forward, then the flywheel could be rubbing up against the back of the block.
#14
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Car: 92 Firebird
Engine: 4.8 LR4
Transmission: T56
Axle/Gears: 3.45 9 Bolt
Re: Grinding During Engine Braking
Sounds like the rear gearset, on the coast side since it goes away when he gives it any throttle, my car does the same thing
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#16
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Car: 1984 Trans Am
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Re: Grinding During Engine Braking
UPDATE for you guys:
Pinion bearing was the winner! Bought a rebuild kit, had a shop replace all bearings in the diff, grinding sound is gone. Interestingly, they said that there was no preload on the pinion when they opened it up, so that bearing was set up to destroy everything. Glad I didn't have to learn that one the hard way. Thanks again everyone for your help in diagnosing the issue!
Pinion bearing was the winner! Bought a rebuild kit, had a shop replace all bearings in the diff, grinding sound is gone. Interestingly, they said that there was no preload on the pinion when they opened it up, so that bearing was set up to destroy everything. Glad I didn't have to learn that one the hard way. Thanks again everyone for your help in diagnosing the issue!
#17
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Car: Yes
Engine: Usually
Transmission: Sometimes
Axle/Gears: Behind me somewhere
Re: Grinding During Engine Braking
there was no preload on the pinion when they opened it up
I kinda wish there was a way to reset it periodically, like we do with front wheel bearings. The comparison is actually fairly comparable. Problem is, especially with a crush sleeve, it's REAL hard to measure pinion bearing preload properly, let alone SET it, whereas it's pretty easy w front wheel brgs; but in reality, only a VERY TINY amount of bearing wear, affects it DRAMATICALLY. Again, just like front wheel brgs.
Once it goes away, the bearings start failing MUCH faster, since they are no longer held in proper contact. The small "tail" bearing, the one behind the yoke, usually shows it up first; but sometimes the larger "head" bearing does. Most rear ends that whine under ONLY either acceleration or coast need bearings, not gears.
If there was a way to restore it occasionally, there'd be AHELLUVALOT less wasted rear axles in the world. Unfortunately I have no solution I can offer. I can only state the problem clearly, but not the solution.
had a shop replace
Last edited by sofakingdom; 04-03-2018 at 05:41 PM.
#18
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Car: 92 Firebird
Engine: 4.8 LR4
Transmission: T56
Axle/Gears: 3.45 9 Bolt
Re: Grinding During Engine Braking
Wouldn't a solid pinion spacer solve the problem? Since you put it in with shims, you can just remove shim to tighten it back up.
#19
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Car: 1989-92 FORMULA350 305 92 Hawkclone
Engine: 4++,350 & 305 CIs
Transmission: 700R4 4800 vig 18th700R4 t56 ZF6 T5
Axle/Gears: 3.70 9"ford alum chunk,dana44,9bolt
Re: Grinding During Engine Braking
I us solid pinion spacers in all my rearend rebuilds.
#20
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Car: Yes
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Re: Grinding During Engine Braking
I use those too; but the bearings still wear, and the preload goes away as a result. But since I can tighten the nut MUCH tighter that way than with a crush sleeve, at least it doesn't back off.
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