rear cab mounts instead of shackles

[swizzlestick]

http://www.ebay.com/itm/CUSTOM-REAR-...aaf12e&vxp=mtr

This is not my listing but thought someone might be interested in this. they are rear cab mounts instead of original shackle style mount. Are the shackle style mounts a problem area? otherwise why would you change them?

[mr48chev]

Thanks, that idea is worth stealing but any one of us here can do it with under 20 dollars worth of material and an hour's time.

It will work great for trucks with independent suspension and boxed or semi boxed frames but I think I would rather run the shackles with stock suspension and no stiffening on the frame.

Since I am stretching my cab 9-1/4 inches that will come in real handy and something like a Tri 5 Chevy biscuit motor mount or a Ford flathead biscuit motor mount might just work as the mount part.

[dwcsr]

I agree on a boxed frame it may be OK but on a stock frames the frame flexes to much to lock down the cab. You'll start popping spot welds and buckling the panels. As for why, because people will change things because they can even if it doesn't need it.

[mr48chev]

I have tossing the idea of using a second set of shackles on mine when stretch the ear cab and as I am planning on boxing the frame somewhat that idea might work better. I'd agree that it might put a lot of stress on a cab on a truck with a stock frame and running gear though. I've had my truck in to some real twists over the years but don't plan to drive it like that once I get it back together and once I get out of my tanktrap of a driveway.

[whitedog76]

I've been thinking about using hydaulic motor mounts instead of body shackles.

They should cushion the ride and provide some vibration dampening also.

GM uses hydraulic mounts on it's new 2500 and 3500 trucks. Supposedly they help the ride quality immensely.

You'd would want ones like these Volvo mounts with a limiting strap, in case you were ever in an accident.

[MARTINSR]

I can't imagine a problem with the shackles. I have mine rebuilt with new bushings and it's good to go. It allows a little movement of the cab but certainly not much. You can't have much movement or something is going to pay for it, like the fenders or hood mounting. The body was designed to move a little all the way up to the rad support. If the cab was made to "float" on those rubber mounts I just can't imagine not having some failure in the fender to cab mounting and hood fit.

Brian

[mr48chev]

I doubt if those mounts would float any more than the stock shackle mounts. The stock mounts are pretty simple and they are inexpensive to redo.

To me the brackets on Ebay look like a 20,00 max investment along with a half hour of time with the power band saw. They do look like a viable option when you have the frame boxed and run an independent front end and possibly independent rear end.

[whitedog76]

The cab is already "floating" per se' on the shackles.

The front cab mounts are only sitting on a 1/4" of rubber anyhow, so I can't see how there would be any more cab movement than normal. You would definately want to have your cab weighted when setting your mount height.

The 1 tons and larger only use a center mount radiator support vs the 2 mounts the 1/2 ton and 3/4 ton use. I'm sure it has to do with frame and body flex. You can lift the fender on one side and make the whole frontend move on a 1 ton.

The front fenders and fender wells are basically just floating there anyway. I'm willing to bet there is alot of strain on the cowels from the factory setup to begin with. It's no wonder the cowel doesn't hold up well to begin with.

[MARTINSR]

You guys make valid points, I know the rear cab mount on 49 (?) and earlier had a center rear mount to allow the cab to rock side to side. Yeah, I am thinking you guys are right.

Brian

[msaintg]

my '47 had only the single cab mount in the rear. I built 4 solid mounts on the S10 frame for each corner of the cab and used the 1" thick S10 bushings. Working well so far.

[mr48chev]

[QUOTE=msaintg;6621872]my '47 had only the single cab mount in the rear. I built 4 solid mounts on the S10 frame for each corner of the cab and used the 1" thick S10 bushings. Working well so far.[/QUOTE

The S-10 frame isn't the issue as it should be quite a bit stiffer than a stock frame. The discussion hinges on the concept that a stock AD truck is designed so that you have a lot of give between the frame and cab and box so that when you cross uneven ground the whole truck flexes but there isn't an undue stress put on the cab it's self.

The general consensus is that with a stock frame and I beam front suspension it's probably better to run the stock mounts but if you have installed an independent front end and boxed the frame and otherwise stiffened the frame the more solid mounts will work fine.

With the Jag front suspension and boxed rails back to the center crossmember I shouldn't have a problem if I mount the cab with more solid mounts than the shackles. Since my cab is going to be highly modified having the cab mounts be a bit more solid may work in my favor. And the simple fact that the truck will never see any serious rough terrain outside of maybe a Utah grocery store parking lot entrance on a road trip. I got hung up on one in Bountiful Utah in 1982 and had to have my wife and kids get out of the truck so I could clear the hump on the parking lot exit with my front bumper.

[cwii]

Glad to see this subject come up, I am trying to build a 47 longbed with the single point rear cab attachment.
I am working in an LS3 with a TR 6060 and it appears to be going to cause the driveshaft to hit the stock K crossmember under the rear cab mount. I have been wondering how I could fab up a new cross member for rigidity and support and still box the frame /support the cab. I see more work in my future.

Thanks,
Chuck