Ebisu Extra 6 Hour - Miguel's Perspective

Whilst I’ve got it on the brain, may as well get this mail fired off! Great fun as usual this weekend. Felt like a real team working together and having fun, which is what it’s all about, innit! J

Thanks for being such a great bunch of guys racing. Even though I only drove one warm up lap, one fast lap and one coming in lap (To test how the car felt) I felt like I raced this weekend. Managing was fun and of course socializing was enjoyable as ever too. I think everyone had fun.

I think we all agree the car behaved better now than ever before, which is encouraging – handles better and everybody was able to set consistently faster lap times, but there’s still lots of work to do! We also learnt it’s important to bring the spares we have for the car. Had we say, lost a drive shaft – or had our badly cracked disc failed (Amazingly it lasted the entire race!), we’d have been out of contention – so no storing spares next time please!

Next race will be in April 2010 at Ebisu again (6 hours). We’d like to get dates for this and sign up the next 6 race drivers ASAP. That way, we can bring in the funds needed for the next stage of preparation. I’m quite happy to not race this event, I’d prefer to spend time trying to understand the car and getting feedback from people – and continue improving it. Maybe I can do the race after that… there should be plenty next year.

The suspension is better controlled now and the car pitches and rolls less – but our conservatively chosen spring rates need to be increased. Also, despite setting toe to zero – we had some blistering of the outside of tyres, especially the left side, which came from heavy under steer exiting the downhill chicane and the hairpin as the bottom of the hill. Drivers need to avoid putting so much pressure on the tyres, since it kills them – but in any case it’s a problem we also need to address with handling. Watching our car in the hairpin closest to the back of the pit area with Mike – we noticed when the suspension at the front was set very low, we’d lift a rear wheel – after increasing front ride height, this stopped – and Rod mentioned the car seemed to under steer more as a result. Tom also said the same, having felt the car was different when he first drove it, compared to the end, when the car no longer wanted to turn in. So we can lower the front a little more, but have to be mindful of rubbing tyres on the underside of the inner fender, especially as there’s vertical pieces of metal which could cut the tyre on a larger bump.

Suspension modifications:

I’d like to see if 16kg/mm springs are able to fit the rear shock (Which would give us a choice of 12, 13.4 & 16 to test with) and uprate the front springs to around 18-20 kg/mm.

Camber adjustment kits are available, which are cheap (Eibach or other brands). The outside of the tyres could be made to run cooler if we decrease camber further. We really should be wearing the tyres out evenly, ideally and of course – not getting this blistering. If we can find it, a eurethane bush kit would also add improvements in keeping geometry correct when pushing hard. If available, this too is usually inexpensive.

We actually have 7.5J wheels instead of 7J, so we could fit 225/45/R16 (If size is available?) or 225/50R16 at the front for the next race to also help reduce under steer – although I think our problem is of front end control rather than tyre width…

I don’t think our Prelude will ever become an evil over steer prone car, it’s quite front heavy so I would also like us to also consider fitting a larger rear anti-roll bar to the rear to help turn in too.

To test these modifications, I think Tom’s idea of going to Ebisu one weekend to test & adjust the car after modifications is a good idea. We could then play with spring rates and damping, plus camber settings. Finally testing if the car would be better with or without a thicker rear stabilizer and have the car best prepared for racing. Maybe we could even go up a day before practice.. assuming weather etc. co-operate.

We would need two new front tyres to do this at least, or all 4 ideally – but it would mean the testing and setup is done before the next race, not set during driver practice.

Assuming our damping adjustment range would be enough to accommodate the spring rates we decide on, then all of the above modifications should be comfortably within budget for the next race – if we choose to go with them. I’d like to see under steer become much less of a problem – as this is what’s slowing us down most now.

Lightening modifications:

A. For sure, we’ll need to lighten the car, especially the front (Which should also help turn-in). So we’ll need to remove air conditioning pump, condenser, drier and all piping, make the a/c fan work in combination with the cooling fan if necessary too (although I haven’t noticed any problem with cooling there anyways). Battery should be ditched and replaced with a smaller dry cell (Kinokuni) and a kill switch also fitted, which should be used to isolate the battery when car’s not in use. We can also get rid of: interior sound deadening on the floor, rear wiper and motor and maybe replace the window winders with manual ones and get rid of the electric mirrors replacing with craft square styled ones , if it’s not too much work / expense. Mike also suggested an FRP boot lid with no heavy hinges (bonnet pins instead?) which would be nice if available. Lightening the car is pretty much free for the most part.

Would also be nice to fit wider rims. We noticed the winning N class car (RIRE wide body NB8C) had major bodywork modifications, so there’s nothing stopping us rolling the arches and cutting the front fenders just below to swage line and spacing it out with z shaped pieces of stainless steel and riveting in place. Easy to do, looks cool and enables us to fit wider wheels.
Other desirable modifications:
The brake does seem quite mushy although it’s not air that’s causing the problem. It may be the master cylinder’s seals that are worn, so we could replace the master cylinder (Easier than rebuilding, which can be time consuming) – which can improve brake feel.

We’ve noticed other N class cars openly *take most advantage of* the rules. Most run without catalysts (Judging by their sound) so we should fit a cat replacement pipe(Taking the original cat in case needed), Mugen manifold (When we can afford it) and – we can also fit some form of open induction kit. Not that these will improve power a lot, but will at least sound like it should! We could adapt an old existing induction kit to work with the resonance chamber already on the car. Should cost pennies to do if not free… with parts I may have lying around.

Rear bumper. I’d like to propose the rear bumper be cut with an upside down “D” shape, similar to the back of a 370Z – and black mesh fitted. Doesn’t have to be a huge hole, just enough to allow air to escape rather than creating a parachute effect. This is only very minor though. Remember we also want to refit mirror bracket in a safer position. Aki’s V-Tec controller also needs to go on.

ATS final gear would also be desirable. Don’t really fancy taking out the box to fit it, but it will become a necessary evil… That is, unless we can find a CL1 transmission used and fit a better final to that…. Would make for a very quick Prelude then… We’d all like to see our car be capable of holding it’s own on the uphill against other N/A cars J!

We can also drill and rivet seams, to help stiffen the car… So much can be done yet, guys!

In brief, I propose for the next race preparation would be
New front brake discs:
6 new tyres (Minimum):
Engine oil change
New springs (16gk/mm ): If only two springs:
Camber adjustment links:
Eurethane bush kit (Not essential right now, but desirable at some point):
Rear Stabiliser kit
Brake master cylinder: .
Dry Cell battery & Kill switch..
Cat replacement pipe: .
Replacement belt for use after removing A/C pump – Need to measure and obtain before doing this removal:
Induction kit: 
Replacement brake duct hose : .
Mugen manifold, and perhaps an ATS final drive gear…

I’ll be off now to do some proper work!
L8R
Miguel