Back in October, I had to replace a transmission mount ( Gear shifter jumping ) no big deal and fairly simple.

Well it happened again Thursday.

The mount has a lifetime warranty so that ($7) part was free to replace and just took me the time/labor to do it again.

My thing is ... is this KNOWN issue in 84 Z-28s? Is it a symptom of some other part not functioning or being broken?

Like I said, it's a lifetime warranty part (no wonder .. its a piece of vulcanized rubber with a stud that is attached to a steel plate that bolts to the transmission .. so there really is not much to the part) .... easy enough to replace ... but I'm wondering if there might be something larger I'm missing.

 

You must be a "spirited" driver! Chances are good that if your granny drove the car, the mount wouldn't be tearing up. If it happens again, you'd want to consider using a poly mount instead (Energy Suspension, etc). They're interlocked and can't tear apart.

 

I would check motor mounts and torgue arm also. seems odd to have 1 go that fast

 

only $7 for the mount? thats your issue

 

So you think it's a cheap part then?


Am I a 'spirited' driver?
Meh .. I don't granny gear it .. but I'm not burning rubber at every intersection either.

I do think that maybe getting a 'better' mount may be the thing to do though.

Anyone have a part number or link to a better one?

 

See that was what I thought too and is the main reason for my posting this thread.

 

A quick search and I found this ... what do you think?

Prothane 7-1604 Prothane Motor and Transmission Mounts





Although ... the image provided is off ... but I'm guessin that would just be because it is a stock image ... my mount has a threaded stud in the bottom which is where it attaches to the cross member.



But I like the design .. DEFINITELY better than the one I have ...

 

As you can see in the cutaway, ain't no way you're ever going to separate one of those trans mounts. That one in the picture may be the one, as they are made to be a universal year fit (the reason for the three holes). Instead of a stud, you'd use a bolt in the center hole. Older Chevy models do use two bolts instead of a center stud on a stock mount, and would then use the two outer holes. Places like AutoZone, etc. carry the Energy Suspension brand mount.
To check the motor mount, you're gonna need a buddy to help. Have him do a brake torque while you look at the drivers side motor mount to see if the portion on the engine raises noticeably away from the frame mount. You have clamshell motor mounts, so even if they are worn the engine isn't going to lift a lot, until the cross-bolt whacks the metal. But the upper rubber would have to be torn through or deteriorated away to let the engine move that much.

 

Awesome.
Thanks a ton for all your help .. I really appreciate you taking the time .. especially the bit on the best way to check the motor mounts.

Any intuitive ideas about any other issues that MIGHT have caused this? Like Carguy68 suggested the torque arm.

Someone in the office brought up installing traction bars ... but that seems a little much.

 

Your torque arm is essentially a traction bar of sorts, it keeps the pinion end of the rearend from lifting and wrapping around like a pretzel. The drawback is that upward force is also trying to lift the tail of the trans since the front of the arm is attached to it. That's what contributes to tearing the trans mount. A couple few companies do make a frame mounted torque arm bracket to take the attachment point off the trans, but I think it's a bit overkill for a car like yours.