Newbie requires track car advice

Post Tue Dec 02, 2008 3:52 pm

Hi there everyone.

I'm looking for some advice.

I've just bought an E30 325i for sprints and a few track days. It's had stuff done to it already including suspension, exhaust etc etc so I'm going to start off pretty much as is. I've bought some additional 15" BBSs off of ebay to put race tyres on and I could do with some advice on those - I was thinking soft compund R888s but feel free to disagree.

I also want to put a smaller steering wheel on (but will need a horn to keep it legal) and I also want a pair of seats and 4 point harnesses. I'd like these to bolt straight in rather than doing any welding.

All advice would be very welcome.

Thanks chaps

Iain

Post Tue Dec 02, 2008 6:37 pm

R888's are very good, Wear rate is low but they hold well. Cobra seat's are good prices but then you need to sit in a few and see what is comfortable, Belt's are again ££ oriantated. No one makes a bad belt anymore..I used kruss as I wanted to mount to the cage but sabelt do a good fixing for body..

Post Wed Dec 03, 2008 10:09 am

Sort the seat before you do the steering wheel as you might find you need to change the postition of it if you move the seat back.

The Cobra Evolution and Sebring seats can go straight in on the Cobra mounts if you widen the holes a little. However they are fixed postion and there is at most 3" of adjustment so it will only work if you are comfortable in that position.

To fit harnesses well you really need a cage or at least something welded in to mount them to, just fixing them to the parcel shelf as some do is a dumb idea & wont give you very much if you ever have an accident.

The horn can always be mounted on the dash so that shouldnt be a concern, but there are loads of wheels with center pushes so either way thats easy.

Tyres.. read your regs and see what you are allowed, Toyo R888 are a good call and proabably fall on the 1B list you will be allowed to pick from. If you are only allowed 1A tyres then your back to road tyres and will be looking out for some soft road tyres like Conti Contact Sport 3's

The 2 biggest areas to imrove performance I'd suggest is weight loss as that is quicker every where, more power is just quicker on the straight bits. The second being toe/camber etc... and for that you will want to modify the front turrets or get some adjustable camber top mounts.

Post Wed Dec 03, 2008 12:06 pm

Race seats and harnesses without a cage is somewhere between a waste of time and a serious liability. OE seats are designed to fail in the vertical; if the car rolls and the roof crushes in, the seat will collapse backward limiting the force to which you are exposed. A race seat won't fail in this way, leaving your head supporting the roof. Not good.

I don't know why anyone uses four-point harnesses any more. Six-points are so much safer and only a little more time and expense to buy and fit.

Steering wheel size is a matter of personal choice. I like my old M-Tech 1 wheel; it doesn't obscure the clocks and the leather gives good grip for sweaty hands.
IMO, steering rack speed is far more important.

R888s are a good trackday tyre; if you're doing short sessions on short circuits the soft compound is the one you need. For longer sessions though (>10 minutes) you may find they overheat.

UweM3's adjustable top mounts will give a useful amount of -ve camber at the front, but if the car is to be used only for trackdays you will get away with JimmyC's mod which permanently increases front camber.

Post Thu Dec 04, 2008 10:49 am

Thanks chaps.

Handpaper, I understand your point about the seats, but I feel you get too much movement/insecurity on the track if you're not in a bucket seat with a harness. A cage is fairly high on my list for the future though as I know you're right.

I'm going for 4 point harnesses because they're adequate for what I'm doing and can be fitted to existing seatbelt points - the two lower fronts for the bottom straps and the two lower backs for the top straps - is that not correct?

My regs (ASWMC) allow 1B tyres and it's looking likely that the MSA will allow any road legal tyre for 2010 anyway so R888s should be fine. I was thinking soft compound because of the sprinting but I guess that could cause a problem on track days - has anyone tried both normal and soft? Is the difference significant?

Thanks for the tips on top mounts - I'll add that to my list of things to do.

Cheers

Post Thu Dec 04, 2008 11:10 am

No, 4-points cannot be fitted to existing anchorages.
The top straps must run horizontally back from the seat; some people have attached them to the parcel shelf but this is not strong enough - a harness bar is the only way.
There is no lower seatbelt attachment point at the front - the receptacle is bolted to the seat. Eyebolts would have to be fitted to the sill and transmission tunnel. Two more on the floor and you can fit a six-point - it's that simple.

Believe me, there is no cheap and easy way to do this, half-measures just won't work. I'm building a similarly-specced 'Ring car on a very tight budget and have concluded that I'm just going to have to spend the money in this area.

I take your point about movement, less is always better, but it's still possible to have fun/get results. I've done 9:05 - 9:10 'Ring laps back-to-back in my 325i; the seats are BMW sports, the seatbelts are standard but have a C-G Lock fitted.

Post Thu Dec 04, 2008 12:36 pm

I need to look at the front fixings then - do the seat subframes from Cobra etc not come with harness fixing points? I'll have a look at the 6 point options as well - thanks for that.

I have to disagree about the rear fixings. The MSA blue book states "as near horizontal as possible" and "not to be located on the floor directly behind the driver/co-driver". A scrutineer told me that they accept anything up to 45 degrees which I reckon is more than achievable with the rear seat belt bottom mounts.

Post Thu Dec 04, 2008 4:42 pm

ICSD wrote:I need to look at the front fixings then - do the seat subframes from Cobra etc not come with harness fixing points? I'll have a look at the 6 point options as well - thanks for that.

I have to disagree about the rear fixings. The MSA blue book states "as near horizontal as possible" and "not to be located on the floor directly behind the driver/co-driver". A scrutineer told me that they accept anything up to 45 degrees which I reckon is more than achievable with the rear seat belt bottom mounts.

They will pass scrutineering but are more likely to cause injury, reason being that horizontal belts stop forward movement, angled downwards behind the seat they stop forwards but also pull downwards compressing your spine. We've always got through scrutineering with a spreader plate behind the parcel shelf (a bar running across noy just the 2" spreader plates), there are a couple of holes beside where the rear seat clips in that are about the right place if reamed out a bit. Harness bars qould be better though as the belt run is shorter. It is possible to bolt to the seat mounts but not advisable, a) because scrutineers don't like it and if having a bad day can turn it down, and b) because in a shunt all of the loading goes through the seat to floor mountings. If the belts are seperate the loading is spread between the seat mountings and belt mountings, less likely to be overloaded and break. The extra mounting points for 6 point are just couple of holes in the floor under the seat with spreader plates, literally 5 minutes to do so no biggie.