Front wheel arch liner/protection

[SCElan]

Hi Guys - nearly time for getting it back on the road CVDS fitted MOT next.

Whats folk using now to protect the inner liner from stones star cracking the paint/gel above???

Pretty sure it had some bitumen type sheet fitted similar to the 60's 70's stuff used to sound proof door panels etc...

Raptor bed liner seems popular but not sure if thats to hard for GRP and wont absorb an impact..

Any ideas before i just make something up and blast on!!!

[Ray419G]

When I rebuilt my Elan, about thirty years ago, I just applied a spray on rubberised under body coating on what I thought were the most vulnerable parts under the arches. I can't remember the exact product I used but it was the sort of thing stocked by most automotive paint suppliers and was the type that can be over painted. As I haven't had any star cracks come through this approach seems to have been effective up to now.

Ray.

[JonB]

This is interesting and I've had the same thoughts myself. For example, on the Elise S1, there is a plastic inner wheel arch that protects the wing underside from stonechips. It is formed to fit, and I think this is an important consideration if we want to do something similar on the Elan. Question is, how to do it (for a home mechanic)?

Meanwhile, my shell, recently painted, has had Raptor applied under the wheelarches, front and rear. My paint man said it is very expensive stuff, but the best. I have some bitumen paint which I may apply on top, any thoughts about that approach?

[berni29]

Hi

I don't particularly like bitumen paint, its actually quite thin. or at least the stuff I have used is.

I have just this week started to apply Gravitex Plus to the underside of my +2 and that stuff is excellent.

If you do want something truly shock absorbing then felt or the stick on sound proofing material would work. Then just paint the Gravitex over that

In either case, Gravitex Plus.

All the best

Berni

[alan.barker]

Jon,
Is raptor with a solvent and is it a problem for the grp. I would think something soft is better to absorb shocks from stones.
Alan

[JonB]

Jon,
Is raptor with a solvent and is it a problem for the grp. I would think something soft is better to absorb shocks from stones.
Alan

No idea, Alan. There's been no problem so far, and the respray was completed before Christmas '23. On the other hand, it's not on the road yet so not tested under road conditions.

[Edit: It seems to be a 2k paint product and there is guidance on their website as to how to apply it to GRP: https://raptorcoatings.com/en/asset/raptor-on-grp/ - moreover they say it is ok for GRP here https://raptorcoatings.com/en/product/r ... g-aerosol/ and that is an aerosol can.]

[alan.barker]

Thanks Jon,
My Sprint was painted in Nov but not used yet.
I spent alot of time on star cracks which i would like not to happen again.
I'll look for something to absorb stone impacts.
Cheers
Alan

[JonB]

A Ford puma and Focus I owned both used a sort of fibrous mat as underarch protection. It was clipped to the body with plastic trim poppers. I suppose we could use something similar only glued with contact adhesive. WOuld also cut down a bit of road noise, perhaps.

[jono]

I've used Gravitex on both Plus 2 restorations and its perfect for this application - the last one I did 15,000 hard road miles inc NC500 and never got a single star crack.

On the latest work in progress I put 8 litres on the underside of the shell then overpainted with 2 coats of synthetic paint - its bullet proof and makes a really nice finish too

PS: I investigated Raptor but it provides no technical benefits over Gravitex for this use other than it can be tinted and sprayed on body colour so I gave it a miss.

[alan.barker]

Thanks Jono,
That looks and sounds like a good idea.
I suppose you can brush or small roller it on.
Alan

[jono]

I just stippled it on with a brush Alan, then you get a 'shutz' gun look but without the mess!

It goes off quickly too as it's a heavy solvent base so you can get a few coats on in day, very high build. It really is excellent stuff and not too dear - lots of offers on Ebay, 6 litres for £40 or so.

[disquek]

I used to race tube frame fiberglass/carbon bodied GT cars. With their thin layup bodies, they were tough on their finish from rock dings in the fender wells.

I saw many approaches from a high end of using a hollow hex-core kevlar inner layer to using common silicone bathroom caulk applied with a bondo spreader in a 1/8" thick layer. Having tried both, in my opinion, the caulk was the best solution. Although the hex-core filler layer is very light, once it's gets ding'd on the inside, it starts to collect water/oil/debris.

This was applied in limited areas based on where it had previously developed crazing. The racer in me hated adding that weight above the COG, but it eliminated the crazing issue for very little money/effort.

FWIW, I have not experienced any issues on my Elan (knock wood). Production bodies are many times thicker than race bodies.

[StressCraxx]

Many years ago, we used 1/2" closed cell foam sheet glued in place using carpet adhesive. The underside of the wings must be cleaned well to ensure the adhesive will stick. It lasted over 10 years and I just bought new, stripped off the old and reapplied again. Cost was less than $30 for all.

[Vic]

I use a layer of "Coremat" and an additional layer of fiberglass (on the inside) to create double skin, with the inner skin taking the impacts. Here is a link to the manufacturer: https://www.lantorcomposites.com/textil ... s/coremat/

[reb53]

I went cheap when I did mine 35 years ago.
Glued some common old bubble wrap under there, then glassed over the top.
Added maybe 6mm, and I noticed the other day the first little chip had arrived, but we have some pretty rough roads here in NZ, and I vaguely recall running over a biggish rock a while back, with a resulting "crack" !

Ralph.