littlesk8cracker

i did a search and found that its a common problem, but didnt find anything on how to fix it. some of you may have seen my recent thread that i finally got my car. its a white 94 6 speed convertible. everything on the car is pretty much perfect but the motor mounts are shot. everytime you get on the car the whole shifter lifts up a good inch or 2 and u can hear the thing slamming around. the guy who sold me it said one of the motor mounts was bad. so i got 2 new motor mounts today from my uncle. now im trying to find out what is required to change them, and if its something i could do myself. i have access to an engine lift and im damn good with cars. whats it take to change these mounts? thanks! cant wait to get these fixed so i can really see what this baby can do!

pianoguy

They have a stud on the bottom, just remove the nut that holds them to the frame. There is a horizontal bolt that holds the top of the mount to a bracket on the engine - loosen those up. You should then be able to jack the engine up enough to remove the bolts and slip the mounts out. I just used a floor jack with a 2x8 between the jack and the oil pan.

In this pic you can see the bracket on the side of the engine that the horizontal bolt passes through:



Here's the mounts with the covers on (I made new covers, old one on the left):

littlesk8cracker

awsome that helps alot. so u can take the bottom bolts out from underneath the car, then jack the engine up, then get the side bolts out and just remove the mounts? sounds easy enough

littlesk8cracker

bump, what has to be removed to jack the engine high enough up? guessing the radiator hoses? what else? thank youuu!!

pianoguy

I didn't have any hoses, etc., attached when I was messing with mine, but I'd think there would be plenty of give. Maybe unscrew the air cleaner box from the radiator shroud. You should only have to jack it up an inch or so.

littlesk8cracker

cool, once the motor is lifted up how easy is it to get to the mounts? do you get them from underneath or above? thanks man, i really wanna get these done

pianoguy

I put mine in from above, but I have headers, so you'll have to see which way you have more clearance. I had the car up on ramps. The covers make it a little putzy to get the mounts installed.

littlesk8cracker

cool looks like ill be doing them myself then. the car has shorty headers so ill have to see which side is easier. no damage to the oil pan by using it to jack the engine up?

pianoguy

The oil pan is plenty strong, just lay a piece of 2x6 or 2x8 on the jack pad to spread the load.

96GS#007

How do you know the mounts are bad? LT1/4 use hydraulic mounts and unless the mount is leaking, it's rare they fail.

Based on your description it sounds like the c-beam bolts are loose vs bad engine mounts.

littlesk8cracker

well i looked into the problem of the shifter movement, i had about 90% of people tell me mounts and its a common problem, then the other 10% said the c beam. i guess when im under the car ill check the c beam but most people are telling me its the mounts

96GS#007

Just remember that L98 cars have conventional engine mounts. In other words, if the opinions came from people with '91 and older cars it really doesn't apply to yours. FWIW. New parts never hurt. I'll be curious what your results are

Mr Mojo

How are people breaking these mounts? In the old days I broke plenty of motor mounts but never on the vettes and I've been racing one for 9 years and the other for 8. Not to mention all the hard driving on the streets.

aboatguy

LT1 mounts are pretty stout


IMO this is why there should be two techs (one for LT1 and another for L98)

PLRX

I didn't know that, no leak-good mount

pr0zac

i second the c beam mount for what you say. i would buy new lock nuts and be sure not to overtighten those bolts. you can easily crack the tailshaft housing and they aren't cheap.

littlesk8cracker

ok, what size bolts do i need and what should they be torqued at? maybe ill give the c-beam a shot first since that seems like the easier repair

littlesk8cracker

got under the car today, grabbed hold of the c beam and pulled on it and it didnt seem lose. checked the rear bolts and they were tight, couldnt get to the fronts because i couldnt get the car up high enough, still need to get some ramps (any recomendations?), but the bar didnt seem loose

96GS#007

You're not going to shake the thing by hand unless it's practically ready to fall off. It is the lone load bearing connection between the back of the tranny (and hence the engine) and the differential. In a static state, it'll feel tight. You need to actually put a wrench on the nuts on the top of the C-beam and then torque the nuts to spec.

The bolts/nuts are available from GM but it's rare to need to replace them. If you find the existing ones loose, add a little blue Loctite to the threads and you'll be fine. The bolts are not something you can buy at an autoparts store or hardware store.

You'll also want to check all the bolts around the tailshaft of the transmission. The threads in the transmission body have been known to fail. A tell-tale sign will be evidence of gear lube leaking.

littlesk8cracker

ok, whats the torque ratings on the bolts?