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Brake pedal travel after laps?
speedster356 - July 1st, 2008 at 06:41 PM

I had the Spyder at Wakefield Park yesterday. Plenty of laps but I did notice the pedal went off after about 6 laps. Thought I had good quality fluid in it but has been there for quite some time.
Stock beetle front with drilled disc and Mitsubishi disc rear, all steel brake lines.
What's happening and how do I fix?
Just one other car out in my session and that was a Challenge series Ferrari F fu#king expensive, very nearly became implated in his rear defuser due to poor brake performance on my part at the Hair Pin.


MickH - July 1st, 2008 at 06:54 PM

Are you using silicon fluid??? Old fluid might be boiling if it is standard less than DOT 4 fluid.Try bleeding the brakes,there might be some moisture in the lines..


The Bigfella - July 1st, 2008 at 07:21 PM

When I track the M5, the brakes go off, the tyres go off - so what's new? Time to stop setting times and have some fun drifting... I changed brake fluid on Sunday. It should be done once a year if you are tracking the car - as it absorbs moisture the boiling temp lowers.

My worst experience with boiling fluid was in a TD Cortina 4.1. I went through a set of front pads in 3,500km - and the pedal went to the floor on the way down the Dorrigo Mountain, accompanied by a very helpful red light on the dash that said "Brake Fail" Yep - boiled fluid. Company car of course.


hellbugged - July 1st, 2008 at 07:24 PM

yep, he more racey/expensive the fluid, the more often you change it...........:crazy:

..........sometimes if boiled then left, it will resemble gel like snot! YUCK


colin - July 1st, 2008 at 07:43 PM

Gday pete, from my experience you simply had brake fade from working your brakes hard.
Probably best to check your lines for air and change fluid,make sure your pedal is adjusted spot on.
After that maybe run some duct to the calipers to direct some air to try and cool them.
But remember to take the ducts of for hillclimbing were heat in our brakes is our friend.

Cheers Col


mactaylor - July 1st, 2008 at 08:12 PM

time to increase the swept area to cope with all that fun!!!!


speedster356 - July 1st, 2008 at 08:13 PM

Cheers guys. I'll get hold of some race fluid during the week for a change.
Next question....
The rear outside corner drops in a turn, if you can understand that? is this a rear spring rate thing (coil overs 914 rear) or do I require a stiffer anti roll bar?


Craig Torrens - July 1st, 2008 at 08:22 PM

spring rate


1303Steve - July 2nd, 2008 at 08:57 AM

Hi Peter

Good to hear your back in the seat. If you want to do cheap upgrade with your front brakes, find a pair of early model Type 3 cailpers, these are the ones with a single bleed screw, they have a 42 mm piston rather than 40 mm and the biggest pad area made for a bug.

Have you ever corner weighted the car?

Steve


speedster356 - July 2nd, 2008 at 11:06 AM

Hi Steve, no haven't done a corner weight......should have by now. :crazy:

I have a set of aluminium Brembo twin piston calipers that will fit with some mods, only had them for about 2 years!
Had a ball the other day at the track.


westi - July 8th, 2008 at 09:32 PM

silly question,do you have braided lines or standard rubber.
standard will give brake fade.


VWCOOL - July 8th, 2008 at 10:36 PM

You need a set of my big fat vented ones! :cool:

Seriously, not much survives the punishment of laps at a track. Pads get hot before fluid does; if the pad overheats because it and the disc can't shed heat quick enough, it doesn't matter what brand of brake fluid you are using. Physically bigger brakes (pads and disc) can mop up more heat before fading and a vented disc (with an air cooling channel down its guts) gets rid of that heat quicker. Cross drilling of a non-vented disc reduces surface area for the pad to 'bite' on and reduces the amount of metal present to soak up heat.

I too was at Wakefield last week and part of my job there was to try and 'save' the brakes of two VEII SS Commodores and two FG XR6 Turbos, a WRX and an STi... plus some others. The Mitsi Evo X and FG FPV F6 have very nice brakes... but they all suffer after a while


colin - July 9th, 2008 at 12:57 PM

Good point westi ,standard rubber hoses in old or poor condition will swell with a big brake application giving you the feeling that your pedal is getting long and your brakes fading.
I replaced my lines with standard new ones which under heavy braking still keeps a firm reassuring pedal.
Is your car registered?, if so check with rta before changing to braided lines. Got a feeling there illegal but maybe wrong, best to check.

Cheers Col


BiX - July 9th, 2008 at 02:35 PM

Also it might be worth jsut bleeding the caliper after every event. Normally the fluid in the caliper will get the hottest and overheat. I know the Evo6Rs rally car is bled normally once, sometimes twice a day at an event and the targa cars including the 911's and Gt3 etc are bled after every day. Plus they have good brakes with good cooling!! Not a full bleed just the fluid from the caliper that has been cooked.


speedster356 - July 9th, 2008 at 04:46 PM

Yip braided lines all round.
VWcool, Had a look at your vented disc setup. Are they 4 x 130mm pcd discs? Are the hubs steel?
Save me some time and give me the part numbers of the discs:cool:
Had purchased some billet aluminium to manufacture a new set of front hubs and bolt up a new disc to the Brembos but it's still sitting on the shelf! (was going to wide 5)
The other is to machine the old disc off the original hubs, use that as a hub for the new hat type disc to slip over. This will increase the track slightly but should be only about 13mm.
I'll bleed again over the weekend and see what happens.


bat69 - July 9th, 2008 at 07:28 PM

Your brake travel could be a number of things. It could be as simple as the brakes getting hot and pads going off, fluid getting hot. It could also be pad knock off. What I mean by that is as the pad wears and with the vibration, braking etc the piston moves back into the piston causing the pedal to get longer or you could be running out of gas in our booster (after excessive braking) if you run a booster. I have had these problem on my suby rally car. I had a spring clips which use to sit in behind the pad/caliper. They use to not allow them in group N in the late 90's. I had a an extra (large) booster cansiter to over come the lage of booster pressure.


speedster356 - July 9th, 2008 at 07:58 PM

Thanks for the replies.
Nathan.Thought I might do Bathurst at the end of August. Conrod Straight Saturday and the Esses on Sunday. You heading there? Been a long time since I've had the Spyder out, would be good to catch up with everyone again. Alan Barlow has had it to easy in the Sprite for too long I think.:blush:


VWCOOL - July 9th, 2008 at 08:23 PM

Quote:
Originally posted by speedster356
Yip braided lines all round.
VWcool, Had a look at your vented disc setup. Are they 4 x 130mm pcd discs? Are the hubs steel?
Save me some time and give me the part numbers of the discs:cool:
Had purchased some billet aluminium to manufacture a new set of front hubs and bolt up a new disc to the Brembos but it's still sitting on the shelf! (was going to wide 5)
The other is to machine the old disc off the original hubs, use that as a hub for the new hat type disc to slip over. This will increase the track slightly but should be only about 13mm.
I'll bleed again over the weekend and see what happens.


yeah I do VW 4x130m and Porsche 5x130, all studded. Yep the hubs are steel


bat69 - July 11th, 2008 at 06:17 PM

It would be great to see you back racing again in your little rocket. I loooove your car. I wont be there in August. August is a bit of a busy month for me. I will be going to Bathurst for the Australianas in Nov. Hope to see you at that one.