Metallic sound going into gear

tkruger

Greasemonkey
May 6, 2015
221
43
NY
Have a 1987 Monte Carlo LS 4.3L stock. ~130,000 original miles. Floor shifter, also stock. There is a metallic clunk when it is shifted into gear from park. Forward or reverse does not matter. This sound occurs when the lever reaches the gear it is to go into. The car is not moving yet when this is heard. I leave the car at idle when shifting. Car idles at the correct RPM. There is no issue with drivability. The indicator is off a bit and does not point directly at the gear but has been since I replaced the bulbs in the dash prior to this problem. It sounds like two steel bars hitting against each other. transmission shifts fine when driving with no unusual sounds.
 

fleming442

Captain Tenneal
Supporting Member
Dec 26, 2013
13,085
113
Check the cross bar where the shift linkage hits the transmission. There is a "sacrificial" nylon bushing on the frame side, and the bushings are still available. If it's not that, check the linkage at the firewall where the column comes through. Or, check for play in the u-joints.




you can use an open end lug nut in place of the bushing
 
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69hurstolds

Geezer
Supporting Member
Jan 2, 2006
5,414
113
Video? Anything to record the actual sound?

My money would be on U-joints going out, or the ring gear/pinion clearances in the rear end are a bit wide, or maybe both. When the "slop" is taken up and stops the driveshaft from turning, it suddenly stops and a metal sounding tone is sometimes heard throughout the driveshaft. Almost like a hammer tapping a bell sound. The reason it doesn't make the sound when driving is that the slop is already taken up. There's a super-far-out-in-left-field chance that the flywheel/torque converter may be loose (it has happened) and can make a similar sound.

With the engine off and in park, and car in the air enough to get under it, and all safety precautions taken to keep it from falling on your head, grab the driveshaft and push it up and down, side to side on each end and check the U-joints. If it moves, they're toast. Check the rear end by rotating the rear tires (make sure both are in the air). It should move a little because even when new there's a little clearance, but if it's really loose, you'll know it. If everything seems good there, pop the flywheel/flexplate cover and check the TC bolts and flywheel to engine bolts.
 

tkruger

Greasemonkey
Thread starter
May 6, 2015
221
43
NY
The sound is from right near the front seat. Not saying it is not the Ujoint but would that sound come from the rear of the vehicle? The sound occurs when the brake is on and the car does not move when I shift. I tried this on flat ground.
 

69hurstolds

Geezer
Supporting Member
Jan 2, 2006
5,414
113
Front U-joint is in the general location. Still, sound will travel through the shaft. We're still just shooting in the dark here because these are guesses from EXPERIENCE. No evidence other than a description is hard to diagnose accurately.
 

bracketchev1221

G-Body Guru
Jan 18, 2018
965
93
This can be in the trans as well. There is an anti clunk spring in the trans that keeps tension on the parts to prevent this. If it has fatigued and broken there is not much you can do other than rebuild the trans.
 

tkruger

Greasemonkey
Thread starter
May 6, 2015
221
43
NY
I realize these are just educated guesses. What I was looking for was a starting point and that is what I now have. One thing experience has taught me is ask others prior to searching too deeply for the answers since there may be that extra common item on model X for only year Y that only people that have been there may know. I will check the u-joints. I was thinking they would not make noise until I started to move since I had the brake on but not considering that the car 'creeps' with the brakes off.
 

tkruger

Greasemonkey
Thread starter
May 6, 2015
221
43
NY
This can be in the trans as well. There is an anti clunk spring in the trans that keeps tension on the parts to prevent this. If it has fatigued and broken there is not much you can do other than rebuild the trans.
If it is that I hope it is just an annoyance. I would not rebuild a smooth shifting transmission just because of a clunk going into gear. I will have to look at the drive u-joints when I get a chance.
 

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