Track day highlighted some problems

[rmaurer]

Hi Everyone,
 
I need some advice on some problems at an Easytrack day at Bedford Autodrome yesterday. Apologies if this is a long post but please bear with me as a I would value some advice/experienced views...
 
I bought the car as a track toy and so the first job was new bushes all round (pillowball and OEM), new suspension and a general going over of the engine etc by Kerim at Powergains (Tiger catback, PFC, remap, full service, a/c removal to improve cooling etc).
 
The main problem - ever since I bought the car, the brake pedal has had a long travel but if you lift and then reapply quickly, this goes away. The pedal is firm once braking force is felt and does not drop to the floor. Lifting off the brakes, waiting maybe 10 secs and then reapplying results again in a long pedal. I have always put this down to air in the system, and yet have now had this bled 3 times by 3 separate garages and each time the pedal travel has improved but not totally fixed the problem. However it was much improved after the 3rd bleeding attempt... until Bedford.
 
Within 5 mins of spirited driving on track, the pedal started dropping again (my dad was out in the first session) and when I went to use the car after a 20-30 min cool down, the pedal was dropping a loooong way (almost to the floor) . Double pumps were giving a better feel/response but this is simply not practical on track and I called it a day after only 2 laps :mad: of gentle braking.
 
Strangely after lunch, I went to use the car to see how it felt and the pedal feel was returning now the car was fully cool. Having chatted with a few friends/guys on the day, we noticed how hot the cat was getting (silenced midpipe is the top item on my list of things to buy) and wondered if the rear brake lines run near the cat resulting in excessive heat soak/fluid boiling. I remembered that garages commented when bleeding the brakes that there seemed to be quite a bit of air in the rear brake lines on each occasion - maybe backing this up...?
 
So, I have a few queries...
 
- I have read that the standard brakes are supposed to be superb despite the small disks but does this really apply for track work?
 
- I\'m ready to go straight for the 929 Master Cylinder upgrade (no brainer) and am also strongly considering ABS removal but what happens with brake balance if you do this? Is the balance valve not part of the ABS pump?
 
- Could the ABS pump have air in the system that gets into the lines in any way (I have no idea how ABS works, presume it\'s just a bypass that relieves pressure when triggered... If so, can air be in the bypass and can you bleed this?!)
 
- Is it worth trying to patch the existing setup or just dive straight in and go for a BBK upgrade? Must admit I\'d rather try to find the problem one step at a time (personal satisfaction and confidence going forwards).
 
A mate of mine was there with an Impreza P1 with monster AP brakes and I have to say they were phenomenal... He\'s running around 360-380bhp, topping ~145mph on the back straight and yet could really lean on the brakes lap after lap with no fade and amazing response. I was rather jealous by the end of the day!
 
Having read a lot of "forum chatter" on RX7s, I was fully prepared for overheating problems, high oil usage etc but following Kerim\'s work and with the PFC lower fan settings, I never saw over 90 degrees coolant temp and that\'s with a standard rad and AST (removal imminent). I backed off when intake temps peaked around 65 degrees but have a 2nd hand Trust/Greddy SMIC ready to bolt on to tackle that.
 
I have to comment on the handling... My dad normally drives a Boxster and was surprised at how much the car "moves" in the bends rather than just sticking. Surprised by this comment, I really pushed on through a few bends and found an amazingly well balanced car that breaks away really smoothly/progressively when under hard power in the bends. If I came away with 1 big positive from the day, it was that the handling is awesome and I put the amount of sideways action down to the fairly new Goodyear Eagle F1 tyres - too much tread depth and I understand they overheat quickly on track. I bought some cheapish Tokico adjustable shocks and H&R springs from the US (<£450 all in!) and they really do seem to respond remarkably well considering how little I spent (wasn\'t sure if engine work/rebuild would be needed at the time).
 
Oh and if you\'re interested, with the standard cat, Tiger catback and leaky downpipe gasket I was only reading 93db on the static noise test which was a relief as I know Bedford have the tightest restrictions in the UK at the moment.
 
Cheers,
Ross

[shaunwil]

Did they flush the original brake fluid out of the system ?

Also are you running stock pads and discs or are they aftermarket. The stock stuff does get too hot but not that quick !

Shaun

[rmaurer]

Did they flush the original brake fluid out of the system ?
 
Also are you running stock pads and discs or are they aftermarket. The stock stuff does get too hot but not that quick !
 
Shaun

Yeah was told the fluid was flushed and ~0.5-1 litre added each time they were bled... The 3rd garage said they went round the car 3 times to ensure no air in the system. I\'m wondering if the master cylinder seals could be on the way out as originally it looked like the car was only braking on the fronts (rears were rusty, even after a run with some hard barking) so think the 929 cylinder will at least prove/disprove that.
 
I\'m running stock disks but the pads are Black Diamond track day spec front and rear... Thing is the bite is always good when they do eventually start to work, just the pedal travel seems to be the issue and that has to be fluid/air surely...?

[rmaurer]

Oh and had braided brake lines fitted as well with no improvement...

[vest_racing]

Would change the master cylinder...

[shaunwil]

Got to be that or the seals have gone on the calipers !!

Shaun

[Papercup]

- I have read that the standard brakes are supposed to be superb despite the small disks but does this really apply for track work?
No, standard brakes are ....e for track work. Even with new disks and pads you\'ll get about three laps before they give up. Or you aren\'t in a hurry. If the car is meant to be a serious track tool you want APs or Brembos. Budget 2-3000.
 
- I\'m ready to go straight for the 929 Master Cylinder upgrade (no brainer) and am also strongly considering ABS removal but what happens with brake balance if you do this? Is the balance valve not part of the ABS pump?
I am running standard ABS system and standard master cylinders. But i have 6-pot APs on the front. My brakes are fantastic, and you can stamp on them all day with no change in performance or feel. I do think that master cylinder upgrades, brake balance, different pads etc are all sticking plaster approaches and a waste of money. Bite the bullet, do it properly, get some proper brakes.  
 
- Could the ABS pump have air in the system that gets into the lines in any way (I have no idea how ABS works, presume it\'s just a bypass that relieves pressure when triggered... If so, can air be in the bypass and can you bleed this?!)
Meh. Dunno!
 
- Is it worth trying to patch the existing setup or just dive straight in and go for a BBK upgrade? Must admit I\'d rather try to find the problem one step at a time (personal satisfaction and confidence going forwards).
No, just get proper brakes
 
A mate of mine was there with an Impreza P1 with monster AP brakes and I have to say they were phenomenal... He\'s running around 360-380bhp, topping ~145mph on the back straight and yet could really lean on the brakes lap after lap with no fade and amazing response. I was rather jealous by the end of the day!
As above...proper brakes. You\'ll never look back.
 
Having read a lot of "forum chatter" on RX7s, I was fully prepared for overheating problems, high oil usage etc but following Kerim\'s work and with the PFC lower fan settings, I never saw over 90 degrees coolant temp and that\'s with a standard rad and AST (removal imminent). I backed off when intake temps peaked around 65 degrees but have a 2nd hand Trust/Greddy SMIC ready to bolt on to tackle that.
 
I have to comment on the handling... My dad normally drives a Boxster and was surprised at how much the car "moves" in the bends rather than just sticking. Surprised by this comment, I really pushed on through a few bends and found an amazingly well balanced car that breaks away really smoothly/progressively when under hard power in the bends. If I came away with 1 big positive from the day, it was that the handling is awesome and I put the amount of sideways action down to the fairly new Goodyear Eagle F1 tyres - too much tread depth and I understand they overheat quickly on track. I bought some cheapish Tokico adjustable shocks and H&R springs from the US (<£450 all in!) and they really do seem to respond remarkably well considering how little I spent (wasn\'t sure if engine work/rebuild would be needed at the time).
 
Oh and if you\'re interested, with the standard cat, Tiger catback and leaky downpipe gasket I was only reading 93db on the static noise test which was a relief as I know Bedford have the tightest restrictions in the UK at the moment.
 
Cheers,
Ross

Andy (track and race RX-7)
 
http://www.pistonheads.com/gassing/topic.asp?h=0&f=47&t=634864&nmt=Papercup\'s%20RX-7&mid=57792

[tinker-27]

i might have a full front ap 6 pot set up for sale soon ,craig 07950399080 if you are interested they dont fade !!!!!!!!

[rmaurer]

i might have a full front ap 6 pot set up for sale soon ,craig 07950399080 if you are interested they dont fade !!!!!!!!

Definitely interested!! What size disks, will they fit under 17" wheels? I\'ll try to give you a call later this morning.
 
Cheers,
Ross

[mar71n]

What the bloody hell are you still doing up at 1 in the morning.

[iaint]

I\'ve only got a slightly upgraded breaks - front discs, pads all round, briaded lines and decent fluid (R600 stuff).

The discs are grooved black diamond.
Front pads Hawk HT10
Rear pads Hawk HP+

I\'ve had no fade at all on track days - even long sessions at Brands and Silverstone.  Not even any issues on the runway at Brunters hauling down to 50 from 170!

If your budget stretches to it then definately go for a big break upgrade but you can have phenominal breaking with modest spend.

The breaks on these things are very very good for their time - 1992!!!

[rmaurer]

Interesting reading, thanks all for advice so far... I\'ve ordered a 929 master cylinder although it\'s a pattern part from Raybestos in the US found on ebay (damn the exchange rate at the moment!). Here\'s a link if anyone else is looking:
 
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=370158734802&sspagename=STRK%3AMEWAX%3AIT&viewitem=
 
Had another look at the car last night and the fluid in the brake reservoir is now a dull grey/black colour. Last time I saw fluid that colour was when the clutch master cylinder seals failed in my TVR and disintegrated, so a fairly good sign this is the main cause of my problems...
 
I\'m leaning towards a BBK as it just means I never need to worry about brakes again, just a matter of finding the right kit at the right price which will fit under my 17" wheels...

[Papercup]

Definitely interested!! What size disks, will they fit under 17" wheels? I\'ll try to give you a call later this morning.
 
Cheers,
Ross

re: disc sizes and wheels. I went for the smallest AP disc (332mm?) as i had not only 17" wheels but they were BBS LMs meaning they are splitties. They fit fine.
 
I also now have a set of Volk TE37s which are monoblock, not a split rim. If i owned only those i could go for the next disc size up (343mm i believe).
 
Largest is 356mm. Forget fitting these in any 17...you\'d need monoblock 18s
 
Also worth mentioning that AP 6-pots come in two caliper sizes, one for the smallest disc, the other for the two larger sizes. Basically less curve. I have the bigger caliper with the smaller disc; availability was an issue so we (me and Re:worx) decided to just go for it. I was sceptical but Re:worx were right; they fit with no issues. The point i am making is that if you bought the larger, less curved caliper and medium disk off Craig you\'d be able to use the calipers with a smaller AP disc if you needed to.
 
I now have three different sets of 17s...when you buy a lot of track tyres it makes a difference! I don\'t regret sticking with them.
 
Andy

[tinker-27]

the brakes have been sold cheers craig,

[AtomicRex]

If you want to have a decent brake balance then use our pedal box