jimlab

My fabricator would like to do between 5-10 at a time, but we'll do an engine cradle GB before the next Cobra IRS GB to give him a break.

chingon

Jim could you elaborate a little on the motor mount differences btwn 'vette and the f-body ones? I'm familiar w/the f-body ones, but not so w/the 'vette's. Any potential engineering flaws in design that you'd like to share or show..? Thanks..

wptrx7

Bring out the whips and chains, no break for him.

Sigh, either way, I'm in for both.

jimlab

Corvette mounts are aluminum brackets or "stands" (one is shown in the picture below, just in front of the exhaust manifold) which bolt to the block and then rest flat on "biscuit" style rubber bushings. They make it a lot easier to drop in an engine since they can be installed/removed after the engine and transmission are already in the car, and the flat mounting surface makes it much easier to use spacers to adjust the position of the engine vertically, if necessary. They also make it possible to provide more than one engine mounting position on the same cradle.

The F-body "clamshell" mounts are probably fine structurally, but they're bulky, heavy, and because of the design, not as easy to drop into cradle mounting points or easily installed/replaced after the engine/transmission is in the car. They also require mounting brackets on the engine cradle that get in the way of things like turbo exhaust manifolds.

wptrx7

This guy thinks of everything. Does it effect the alternator (f-body).

jimlab

The accessories are far in front of the motor mounts. They only look close because of the angle of the picture. Note how far even the SBC conversion mounts are from the front of the block...

chingon

hmm., thanks for the explanation. so solid mount brackets from the looks of it? I have no experience w/vettes but most solid mounts seem to transmit a good deal of engine noise and vibration to the car, is this the case w/these? Is there a rubber doughnut perhaps sandwished between mount and chassis? What's the going rate for these$$? may consider using them when fabbing the fc mounts..

Again thanks.

just re-read your statement, forget what I said..

dclin

iTrader: (4)

Jim, is there or could there be in what you envision a provision in this tranny brace to tie the differential in too - basically provide the support that the torque arms from Hinson and Granny's provide - in case we should want to keep the OE diff pumpkin?

jimlab

Since a local friend may be going to the dark side also, I'll probably be looking into a support that allows retaining the stock diff, but without a torque arm. Of course, you could always use someone else's torque arm with my engine cradle and save me the hassle.

impactwrench

Jim,I like your old avatar better

dclin

iTrader: (4)

Given that there is no longer any reference to your feelings about the torque arm 'solution' on TC, I take that it is now OK to use one? No, I'd rather have an option. Could you share the rationale against torque arms, BTW? I really want to know why you are against it.

jimlab

It was no longer accurate.

jimlab

Don't need one.

The differential in an IRS car is fixed and is not intended to move. The torque arm in a Camaro is required by the live axle/differential which cycles up and down with the suspension. On an FD, all the torque arm (or PPF) is doing is locating the front of the differential for correct pinion angle. That job done, it's just extra weight and takes up room in the transmission tunnel that could be better used for the exhaust system.

My main objection to the torque arm is that it mounts to the transmission brace and acts like a long lever on that brace, which is why people have had the mounting pads for the transmission brace tear off the floor pan. They're only tack-welded on, with some seam sealer around the edges, and were only meant to work laterally as a brace system to increase the rigidity of the transmission tunnel. They were never meant to support the load of the transmission and differential.

dclin

iTrader: (4)

Thanks, very clear now and makes sense.