Jock straps

[chris.richard]

What underbody protection is considered necessary for tarmac work? Martin, what did you protect on yours? Dave W?

[SUSIT]

Full length front to rear for you chris and then watch the temp soar, and on a serious note does fitting a sump guard have any effect on cooling?

[chris.richard]

It should do - a significant amount of oil cooling occurs from the sump, so reducing airflow over it will reduce cooling.

[rutthenut]

My car has thin (2mm?) ally undertray at the front, from the radiator mounting bar back to the floorwell. It was fitted to try and improve airflow with a smoother underside.

Actually seemed to help keep the front under control when at speed, even though I suspected it may lead to front-end float. Presumably, radiator air is now forced out from the top of the bonnet rather than also going under and around the car from the front compartment.

Further convenience factor - it gave me a surface to mount the extinguisher to.

Anyway, on the 'tarmac' event in Belgium, the 'whites' that they used (concrete roads, or very old broken tarmac), this lightweight panel also served as a form of sump guard. It has got a fair number of dents and scrapes that it did not get from circuit racing!

If rallying, I would recommend that you fit a similar front undertray, perhaps of slightly thicker material, as it can help. And because it overlaps the front chassis crossmember, it means that part of the car won't get caught up on any severe contact and would act as a 'sledge'.

Seems a further recommendation is to fit a metal tray and then mount some Karlan (?) or other tough plastic sheeting over it. More of a requirement for rough stages than smooth tarmac, I guess.

At the rear, a full sump guard could certainly lead to reduced oil cooling from the finned alloy sump - but you do want to protect that as fracturing it would lead to more direct engine cooling than you would desire!

Another mod on my car was to lower the drivers side floor pan, which in my case ended up half-inch lower than the side sills. Not good when running with low suspension settings on the bumps - and you can feel every contact with the ground through the seat mountings that way :(

However, this is now lower than the sump, which is on the same side, so contact with the floorpan has the strange benefit of lifting the car and saving contact with the sump!!!

What I would like to suggest would be at least a couple of fore-and-aft tubes or bars that form a protective cradle under the sump. These could be mounted to the transverse chassis rails at front and rear of the engine bay, and would need a certain amount of clearance from the sump, in case they do get knocked up and into it.

You could choose to fit a full sump guard anyway, but remember that the exhaust pipe also runs through that section, so yet more heat management issues to consider. The guard could always have a number of holes in it for air to get through if that may help.

Think that's enough from me on that subject...

J.R.

PS = picture shows the resultant damage to my lowered floor pan

[rutthenut]

One other thing - if the mounting bolts from your radiator have any excess thread protruding from the base of the mounting point, shorten them.

My 'rallying' trip managed to bend these back, which could potentially wreck the radiator.

J.R.

PS - Another photo of my beat-up floorpan after Boucle de Francorchamps

Moral of this story? Don't go rallying with a lowered floorpan, low suspension and heavy driver + co-driver ;)

[chris.richard]

Karlan (?)

Kaylan ;)

I take it that nobody has done a rear sumpguard then? Hmm, is that coz it's not needed, or coz nobody has put their sump at risk yet? :confused:

[Martin K]

Sorry for the delay in replying.

I used a sheet of dural - 5 or 6mm as I recall - that was fitted to the underside of the rear chassis rails and ran full width and from the rear floor to the rear chassis rail - but with cutouts for the gear linkage.

Oil cooler did the job and I didn't have any over heating problems, though I only used this on rough stuff not on tarmac so it only did a couple of events which were DNFs for other reasons.

[Marmott]

I use 6mm dural front on both tarmac and road tarmac, going from under rad to 300mm back from where your feet are to protect driver also

I have side vents in inner wings to aid cooling but even in traffic no problems, these are for when the light pod is on on long hot stages as air flow can be affected.


Also carefull positioning of mounting points will strengthen chassis for the inevitable crash down from a yump
Stratos does not fly well

At the rear its a must , 6mm dural fron 250mm infront of engine sump and angled up , to 100 mm back from engine, no holes in it for cooling as bricks enter through holes and sponge between sump and guard to keep bricks out

oil cooler in inner wing.
Gary

[chris.richard]

thanks, Gary, thet's very helpful. :)

Also carefull positioning of mounting points will strengthen chassis for the inevitable crash down from a yump

Can you tell us what the best mounting points are? Any photos?

At the rear its a must , 6mm dural fron 250mm infront of engine sump and angled up , to 100 mm back from engine, no holes in it for cooling as bricks enter through holes and sponge between sump and guard to keep bricks out

That's just mounted at the sides?

[SUSIT]

Chris,
We are talking Corse S not Hawk with marmotts car

[Stratos]

I only ever bothered at the front, as I only ever do tarmac rallying, and even on rough stages, it's unlikely that you are going to clout the rear sump, unless you go so far off-road that you run over boulders or tree stumps - and, if you do, you'll have done so much damage under the rest of the car, that potentially hitting the sump on something is going to be the least of your problems.

I've had some fairly horrendous "offs", and never yet done any damage to the sump.

All I have ever bothered doing is fit a sheet of "Kaylan" under the front as a "Skid-plate" - mainly to protect the water pipes where they go into the tunnel.

If you are planning on doing forest rallying, then your car will have different requirements to mine, and you probably need more protection.

Kaylan is quite cheap. Easy to cut. Flexible - so you can bend it into position. And easily replacible.