# Strange Grinding noise



## jtwoods4 (Dec 22, 2011)

69 GTO.

A strange Noise is coming up through the transmission tunnel where my shifter mounts to the transmission. This started happening after I installed a new clutch and M22 Muncie.

We put the rear axles on jack stands and drove through the gears and the noise was not there. When the wheels are on the ground and the car is driving on the road noise comes back.

The noise does not happend all the time. It appears most in 3rd or 4th gear when running around 2000 to 2500 rpm. It is not there during steady driving at a constant rpm, but only during mild acceleration up around 2000 to 2500.

Here is the youtube video of the sound. You will definately know when you hear it. The video was shot at speed less than 40 mph.

Grinding Noise 69 GTO - YouTube


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## geeteeohguy (Feb 2, 2008)

Was the car always a 4 speed? What was in it before? Was the M22 overhauled? It almost sounds like the starter is trying to engage when your driving. Bad bearings can make similar noises, but do it most of the time, usually on deceleration. Does it do it when cold, or when warm, when the oil is thinner? You ARE using regular non-synthetic oil, right? Another thing: check the driveshaft, exhaust, and rear end. It could be a rear end noise telegraphing up the driveshaft. Many moons ago I went to pull my noisy and worn out trans for an overhaul, and when I went to pull the driveshaft, found out it was my rear end that was grenaded, not the trans. It sounded and acted like a grenaded trans, though, driving the car. It happens. What's certain is it's metal to metal contact, and it isn't good. You can buy/borrow/rent electronic and mechanical stethescope style listening devices for just this sort of issue.


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## jtwoods4 (Dec 22, 2011)

Yes car was always 4 speed. I just swapped the old transmission to a brand new and fresh built AutoGear M22 Muncie. I am using the correct amount of 85w90 gear oil. My transmission builder also suggested that the sound may be a rear wheel bearing telegraphing up the drive shaft. I swear to god it sounds like it is coming from the transmission or bell area.


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## jtwoods4 (Dec 22, 2011)

Could it be that is the normal sound of a M22 "rock crusher" transmission?


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## Rukee (Feb 8, 2007)

no, it shouldn't make noise, specially random like that.
You put a pilot bearing in the crank, right?


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## geeteeohguy (Feb 2, 2008)

I agree, Ruk....noise is not normal. Pilot bearing is an excellent point.


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## jtwoods4 (Dec 22, 2011)

Ok guys thanks. Dropping tranny tonight and looking in bellhousing. I did install a piot bearing about 500 miles ago.


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## Rukee (Feb 8, 2007)

Maybe before you drop the tranny drain the fluid out and look for any metal shavings. Might be a bearing coming apart.


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## geeteeohguy (Feb 2, 2008)

Yeah, and if/when you remove it, pull the side cover and check inside for bad ju-ju.


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## jtwoods4 (Dec 22, 2011)

Well I did some research and other guys are reporting a similar sound with a metallic dual disc clutch, Mcleod RXT. Sounds like bolts rattleing in a coffee can in the 1800 to 2000 rpm range. Apparently its normal.

Pulled thr reans and the throw out bearing and pilot bearing are in excellent shape. No strange wear marks on the input shaft.


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## geeteeohguy (Feb 2, 2008)

I would change the clutch, then. Unless you want to deal with the noise.


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## Rukee (Feb 8, 2007)

Yeah, I wouldn't be able to deal with that either.


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