RMC Owners & body mounting ?

[Rob. Smith]

G'Day folks,
My little project is progressing along ok, but it has been mentioned by my engineer that I should have a "gasket" between the body and the chassis.
In my enthusiasm I have cut out these "gaskets" from silicone rubber which doesn't compress. They are dove tail interlocked and will be glued to the chassis with a similar silicone compound. The doubt has arisen...do I really need these "gaskets" ? Has anyone else done this ? Does anyone with a separate body / chassis set-up have any problem with body squeaks ?
I have a second thought that unless the body is a perfect fit. The "gasket" would let the body move around and lead to stress fatigue in the fibreglass around the mounting bolts. After this little rant I'm pretty well convinced that I don't need to fit the "gaskets" but I'm curious to any one else's opinion.
What do you think ?
Smithy.

[stephen low]

Rob

Even in the short time I had my GForce on the road I'd wished I'd remembered to fit rubber between body and chassis. You can definitely hear noises.

Have ridden a few times in a cobra mate's 2nd GF with rubber in place and it is dead quiet.

Don't waste too much money on seriously expensive silicon rubbers though, I am sure my mate just visited clark rubber for something fairly inexpensive. I'll try to find out this weekend and let you know what he used.

Short story, use some form of rubber spacer!

Hope this helps.

Steve

[Rebel1]

Yep, fit a gasket. I have ridden in RMC's with and without gaskets ..some without gaskets are dead quiet...some are not. All with gaskets are dead quiet.

The body ( moreso the inner tub) on an RMC and I suspect a G-force do not fit well to the chassis. Hence in places the tub is off the chassis..other places it fits tightly.

No need for expensive gaskets. The easiest and best to fit is the 50mm wide bitumen impregnated builders foam. The black sticky stuff which is quite thick (maybe 12mm) but compresses to nothing.

The only problem with it is that it does collect dust on any exposed edges so make an effort to trim any foam which is exposed after fitting.

Cheers

[OZVENOM]

I have built a few rmc cobras and i would recomend putting in the rubber gasket . I use self adhesive sela rubber from bunnings it comes in 3 grades of hardness i use the medium ands its dead easy to fit its an inch wide so i run to strips side by side on the wider chassis parts .
no glueing it takes about 1/2 an hour to fit it up.
Another tip for you on rmc is to trim all your edges before you fit the body i trim the wheel arches down to 10mm wide it still keeps the strength but allows more tyre clearance.
oz.

[Baz]

Rob,

Rebel is spot on regarding the manner in which the RMC tub sits on the chassis. I found that the securing bolts around the front and rear of the vehicle pulled the body down tight, whereas the mounting bolts along the chassis under the drivers compartment sat up , sometimes as high as 5mm. I even had to purchase longer bolts so they could reach.

I don't think it's the fault of RMC, as in my case, I removed the body from the chassis and baked it in the summer son for a couple of weeks tio condition the gel-coat. Some days it was over 40 degrees. No doubt this 'baking' tended to slightly alter the shape of the body shell.

As I hate any type of squeak or rattle in my cars, I placed spacers throughout the body.

I don't think that the engineer you spoke to was stating a Regulation Requirement, but simply advising you of something which he knows would please you in the long run and something that would be relatively easy to fix now, but a bugger to do further down the track.

Do yourself a favour and fit the spacers throughout the car.

[LoBelly]

Well, I didn't put any type of gasket between the body and chassis of my RMC and I can't hear any squeaks at all when my car is running.

However, if I were doing it over again it is something I would consider.

Like the others I found a degree of inconsistency in gap/fit through various parts of the body and ended up using large washers and tightening the down the bolts over time to get a firm fit (certainly heard a few creaks then)

Good luck with your build

LoBelly

[stephen low]

Michael

With your engine and side pipes I don't think you would even be able to hear a stereo should you ever fit one let alone the creaks of protest from the body on chassis.

[Rob. Smith]

WOW
Thanks to everyone for the reply info. I've got all the gaskets cut out and the "glue" is supplied by my employer. My main worry is whether the body will fatigue around the bolt holes.
A bit of history...I bought the kit through a dealer in sydney. "Ted the tuner" and he was a slick salesman. He swapped the bodies from his kit to my kit. Later it became obvious that my purchased body was far better than the one I received. (most likely a deal he did with the supplier to get an original buck for a cheap price) I was originally pi$$ed but in the long run I got a "seasoned" body that only took a few mods to fit the chassis properly. I only found out the body was wrong when the windscreen frame didn't fit at all. Any way after all the mods that I have done to the body work, flat floor, round tunnel, heater ducts and oil cooler ducting. I'm not too concerned.

[Aussie Mike]

Hi Rob,

If you are woried about damaging the glass around the bolts you could always make up some crush bushes. I guess that's what you'd call them?

The floor of my CR has a foam core between 2 layers of glass. Very strong construction over all but weak when you bolt through it as it's easy to crush the foam core. I machined up these bushes for my seat mountings which also hold the body on. They sandwich the glass in place but dont let you over tighten it and crush it. They also provide a solid connection between the seat base and the chassis.





Cheers

[Rob. Smith]

MIKE ! Great Idea. I've got a few of these on the body. Seatbelt mounts and I've removed the glass completely under the fuel tank mounts. I might look at some of the main body mounts too. Holey Dooley what is the front seat track bolt going through ?
Smithy