LotusGTR

I might have already asked this, but I have some 355mm 2 piece rotors that need very light machining and need to find a brake shop that has experience with large rotors / big brakes and has a good quality set up. The brake kit supplier warned me not to go near the 'high st' places to get this work done. I guess there is Race Brakes but that's over on the west side. Any located in the SE that you guys have used and know to be recommended. Thanks.

Hello. Agreed. I'm doing the wheel bearing and light machining thing to see if that sorts it. I'll get every moving part up front wiggled and jiggled and anything with any slop we'll get sorted too. Soon I will have the $6m car.

Mum's the word . See you on the track next time.

Righto, we spoke in hushed tones about my mods right?

Gunmetal 32 with gold 5 spokes?

I've just got off the phone to the guy who supplied the brake kit and he suggested the following. Worn wheel bearings under lateral load will move (though still not making any noise or outward signs of wear). The disk then moves too. This disc movement then causes part of the disc to be in contact with the pads. The disc then picks up pad material in certain spots and causes the steering wheel judder. He said it's more likely to be picked up in the steering wheel than the pedal. The fix in his opinion is to very lightly machine the discs, whilst they're off check the hub prep, replace wheel bearings (said go Nissan not ANOther brand) and re-grease with something better than what they come with.

Thanks Gary. I would say it ain't the track as it's just not that kind of thing. You can tell by how it feels and where how it happens. Well I've spoken to the guy who fitted the brakes who said it's possible the hub prep issue exists but highly doubts that's it. I also paid him to mechanically inspect the car before it went onto the track i.e. on the hoist, wheels off, check bolts, suspension, brakes, fluids, etc and whilst he did not specifically check for the wheel bearing or lower ball joint issues he said based on that check and his general knowledge of the car there are no obvious signs of these components needing replacing (to solve this issue) He did agree with the wheel bearings possibly being the culprit, but with there being no real sign they are needing replacement (other than they are 20 years old.....) it comes back to the game of replace a part and see if it's that........Expensive, time consuming & frustrating. I could invest in having the rotors pulled off and do all the checks but if that turns up nothing then I'm back at sq 1 having invested in labour that could be fitting a part that could fix the problem......Damn old fast cars! Front and rear Nissan bearings with seals are the best part of $1,000 plus fitting so it's not a cheap exercise (yes I could do the fronts only & and funnily enough they are much cheaper than the rears). Lower ball joints are nearly $500 plus fitting. Do you know of other wheel bearing options that are not Nissan that are worth considering?

Thanks Gary. Some further thoughts. The hub issue you mention, I'd be disappointed if this was the case as the guy who fitted them does great work and is an ex racer so should have done the right thing. I will ask him. He's decent enough to be honest if he remembers there being any issues. I'd not considered the wheel bearing issue so will keep an open mind on this, especially as my brake kit supplier had mentioned in some detail (at the time of purchase) that worn wheel bearings could be a cause of pad knock off, of which I reckon I had a bit of, the first time I went out with them. The vibration has happened with vary degrees of severity with 2 totally different brake set ups. So the hub issue is either common to both separate set ups, or it isn't the brakes, and is something to do with the wheel bearing or suspension. The first time was at PI with std brakes and no mods done to the suspension. The second time at Sandown with all the suspension mods done. The problem was far less of an issue after the suspension mods were done. At PI I had to give up driving fast, at Sandown if was a little annoying but didn't stop me. I guess if I could eliminate each part as a potential cause that would be the most logical way to approach the problem. So, in what order and how should I approach it? Inspect / test the lower ball joints for wear? How? Inspect / test the wheel bearings for wear? How? Remove rotors and inspect the rear of the hat / hub for good prep. Perhaps machine the friction surface to make 1000% sure it is not some sort of rotor distortion issue Clearly I do not want to replace lower ball joints, wheel bearings, and machine rotors as it's a bit of a blunt and expensive way to solve a problem. Any other thoughts as to possible causes not discussed yet?

Perhaps this helps in the discussion (that might ensue). I've circled the areas it seem possible that might be the culprit(s). Front_Suspension.pdf

Well I never adjusted the suspension as it was a very wet and cold day and it seemed sticking with the softer setting was most prudent. First time on the track with the DMS fitted and I was really happy. Sandown has some nasty bumps coming onto the main straight and a fairly large dip just prior to the braking point for turn 1 and I was really impressed with the compliance and control in these areas. Understeer was really under control and oversteer only happened if you applied the throttle and was very controlable (your choice). Body roll was pretty respectable as judged by the pit lane. I was keeping pace with a 997 GT3 and a few other good cars so I'll assume my overall speed wasn't too bad (no timing). I did get convincingly munched by an R35 GTR though...

Symptoms I was at Sandown this weekend and whilst braking from speed (say 100km/h plus, but on the back and front straight at Sandown so 200+ there I’d guess) there is a vibration evident. The faster you’re braking from, the larger the vibration. It does not manifest its self through the pedal, but through the steering column. There is no specific pedal feedback at any speed so it is not warped rotors. I’ve had this before at Philip Island with a totally standard set up (i.e. before all the mods mentioned below), but much more severely, and only braking from high speed (i.e. long straights). Set Up I have new (perhaps 2000 kms and 2 track days old) AP CP5555 calipers front and rear with 2 piece rotors (355mm and 343mm). Suspension set up new adjustable upper control arms, new castor rods with spherical bearings, an aftermarket swaybar, and DMS 50mm coilovers. I’m running a bit of castor and camber and about 1mm of toe in. Tyres are RE55 245/40/18 on a 9” rim. The Question I need a diagnosis. I’m thinking I need to look at the bits that have not been replaced or upgraded as the culprit here (I’m assuming the new bits are the right quality and have been fitted right). What’s left? Lower ball joints? What else? I’ll eventually end up giving this to a suspension specialist to fix, but I’d rather go into that conversation with some better ideas than I have now, so any assistance would be gratefully received. I need to get rid of this vibration as it shits me and saps confidence whilst under hard brakes. Could be safety and wear issues lurking in there too. Cheers, Nick.

My RE01Rs look, feel (to the touch) and drive nothing like my RE55s. Add to that different sidewall construction and I'd argue they are very different tyres and not comparable at all. I'd say an RE01 is simply a high performance road tyre. RE55s etc are a road legal track specific tyre, which IMHO are the most appropriate choice on all but a flooded track (based on a trackday I did on Sat). 5-7 fast laps on a soddent track with ambient at about 8 degres and they were very warm to the touch and generated heaps of grip. R compunds all the way at the track.

Just in case someone searches for this later I've done the trackday and the r compounds were great in the wet. It was amazing how much heat I got into them. It took a couple of laps to get the heat in but once done they gripped a treat. I'd highly recommend them if available.

Lots of lolling going on at your end! Must be having a good time Cheers for the advice, it's sort of patchy rain so I'll go for 32.

Bumping it guys. Need to hear from you as I'm leaving for the track at 8.00 tomorrow.

OK, lay it on me brothers. I need to be told directly what psi to set my tyres at tomorrow. __psi for a wet track. I'd just whack 30 in em without any further guidance so if that aint the figure, can you give me one? It'll be wet and cold at the track tomorrow so I'll not be stuffing around with pressures whilst I'm there - yes, I'm weak as piss. I'm also fiddling with the suspension so will only have time for that. Cheers.

Thanks. Can you tell me off what base? e.g. normally set to 28psi cold for dry conditions. Run 28+4 for wet. etc etc.

Suggested tyre pressures gentlemen?

Good shot. Nice camber at the front there. You under brakes?

Yup. That's consistent with my experience with R specs in the wet (on the road). Always been pleasantly suprised how good they were. Thanks for all the feedback.

Great. Mine are 1 track day old and have plenty left. I'll watch the braking. I guess depending on the day, dry lines might appear so all the better for the RE55s.

Thanks guys. I'll take a look at the forecast the day before and perhaps speak to someone who knows the track and see what their view is. Wish me luck as iIm nervous being on the track in the wet! I guess I'll have to slow down, feed the speed in, and not take any risks on the faster corners.

Well I'm off to the track this weekend and will be adjusting the suspension to see what difference the settings make in this environment. Any suggestions about how to progress from a point of view of softer to harder on both bump and rebound and perhaps how these relate to each other i.e. I'm it's not recommended to have the slowest rebound with the fastest bump etc. I'm thinking full soft bump, to medium to near to full hard (kersnip) with the rebound following 'to suit'. I'm going to do large adjustments to the bump as I suspect a couple of clicks (out of 21) will not really be felt (by my ass anyway). Any suggestions appreciated. I'll probably ring DMS and ask them for their opinion too. EDIT. DMS say to have it on 12 for bump and 1 for rebound. Progress bump by 2 clicks at a time and leave rebound alone. Said 12 was good for the dry and 14-15 good for the wet (getting softer. The softest is 20). If you're at full hard on the bump he said you need harder springs as body roll should be mostly controlled by this and not the damper. Hopefully I'll not find that happens.

I've got a track day on Sat at Sandown and the forecast looks to be wet. I have RE01Rs for the road and RE55 (SR2s? - can't see the car now to confirm but not wet weather ones, just normal) for the track so not sure what's best for the day. I've run the RE55s and some Dunlop D01Js in the wet (road) and was always pleasantly suprised by the grip on offer. Any thoughts on the best way to go? My guess would be that other than large amounts of standing water, the RE55s would be a better bet. Commnets and suggestions please. Cheers.

Well I've still hardly driven it but my initial impression was it was still a little too hard for my journey to work. I've been at Techsport this morning and they took me through how to adjust the set up. Very simple once shown. We took the bump settng from 15 (tarmac rally setting) to 20 (softest). We left the rebound on 1 (0 softest, 3 the hardest). The difference is massive. The car rides like a limo, but lacks the lovely controlled feel of the 15 setting. It's still more than enough for suburban driving and for Sunday drives and the track it's no more than a careful half hour of adjustment to set things up for higher speeds. I'm happier than ever with my choice of adjustable suspension, and the support that's come along with them. I'll keep fiddling with the settings and post up any results. The pity is I don't drive it enough......