99 manual transmission mount-vibrations?

[feta]

i have been chasing an annoying vibration/shaky shifter for a while:
-more noticeable under load at highway speeds in 5th 65mph+
-slight rear view mirror vibration through gears under hard acceleration
-sometimes vibration in steering wheel (might do rack bushings next)

done:
-replaced all u-joints in drive shaft
-balanced/rotated all wheels

99, 5 speed, ~100k miles prev owner towed a big boat sometimes

I will continue down the list of most likely issues, however I examined the mount and saw this, notice the gap below the washer that looks suspect.

Does the mount look shot? My research tells me that it is.

 

[Hesk11dog]

is it hard to get into any gear? Is there shinny metal around any of the mounts? Vibrations are tough things to narrow down because it could be anything from gears, axles, transmission, joints and a lot more. Check the fluid in the diffs and transmission. try to tighten down that mount if you can. I'll check mine on my break and see if it looks any different. I'll snap a pic if i can.

 

[feta]

easy to get into gear, however there is a slight whine to the transmission

no shiny metal

fluids changed recently to redline, no improvement

tried to tighten when I saw it, I think there is some spacer or something going on in there.

 

[Hesk11dog]

the picture of mine. Looks about the same, with the gap on top. My gap looks a lot larger though. The rubber on mine is good and pulling and pushing on everything doesn't show any play. Normally I feel bad posting pictures of PA rust but you are from the burgh so it is not as bad. :fro:

 

[feta]

Thanks, I think both of ours are bad. Mine might have additional issues with something else out of balance or worn from towing. I believe it should be tight under that washer, since it has a set space allotted underneath there with a spacer. I think if one were to jack up transmission a little, it would move up instead of stay braced by the cross member.

My research on other sites seem to point to mounts as a possibility. Engine mounts could be a suspect as well if this rubber has deteriorated.

I think everyone is a bit envious of the rust-free trucks, after I took the pic I thought the same thing about PA rust.

I just make sure the frame is fine, the rest can be replaced. My 96 frame suffered from the rust monster, I have taken counter measures with the frame on this one.

 

[Hesk11dog]

i've done some cutting and welding on mine. had a spot completely rot out and had to be replaced. I clean with a wire wheel and paint every fall.

A new transmission mount (beck/arnley) from rockauto is $47. Have to pay some shipping. Might be able to search around and find a better deal. Not sure what it would take to replace. Maybe just have to brace the transmission and unbolt. I would definitely soak that sucker a couple times before wrenching on it.

 

[feta]

ordered a new one and some other maintenance stuff, I will update after with results

 

[Chuckles89]

the picture of mine. Looks about the same, with the gap on top. My gap looks a lot larger though. The rubber on mine is good and pulling and pushing on everything doesn't show any play. Normally I feel bad posting pictures of PA rust but you are from the burgh so it is not as bad. :fro:

Mine looks like this, but I inspected it when I had the transmission pulled and it appeared to be fine. I also don't have any excessive movement in the shifters. I'm leaving it 'till they start to move excessively.

 

[BetterontheMtn]

the picture of mine. Looks about the same, with the gap on top. My gap looks a lot larger though. The rubber on mine is good and pulling and pushing on everything doesn't show any play. Normally I feel bad posting pictures of PA rust but you are from the burgh so it is not as bad. :fro:

Bringing this thread back from the grave because I can not find any information about what this bolt/bushing combo on the transmission mount ACTUALLY does.

Just swapped a new mount in on my wife's 97 Auto and the bolt was loose, so after installation I tightened it up with a wrench.

Is there a torque spec? Is there a purpose? Will my skin ever grow back on my knuckles?

 

[phattyduck]

Bringing this thread back from the grave because I can not find any information about what this bolt/bushing combo on the transmission mount ACTUALLY does.

Just swapped a new mount in on my wife's 97 Auto and the bolt was loose, so after installation I tightened it up with a wrench.

Is there a torque spec? Is there a purpose? Will my skin ever grow back on my knuckles?

It is a travel limiter for two purposes: Keep the drivetrain from moving too much that it damages the mount (4Lo, 1st gear can put massive torque on the drivetrain!), and to keep the mount together in case the rubber fails on the mount (accident or age).

All motor/trans mounts should have a secondary fail-safe retention mechanism. (the engine mounts have bent-over metal tabs for the same purpose - other vehicles use a bushing-sleeve arrangement)

-Charlie

 

[BetterontheMtn]

It is a travel limiter for two purposes: Keep the drivetrain from moving too much that it damages the mount (4Lo, 1st gear can put massive torque on the drivetrain!), and to keep the mount together in case the rubber fails on the mount (accident or age).

All motor/trans mounts should have a secondary fail-safe retention mechanism. (the engine mounts have bent-over metal tabs for the same purpose - other vehicles use a bushing-sleeve arrangement)

-Charlie

This makes sense.
Thanks Charlie!