Boiling ATE TYP200 On Track?

[MRichards99]

I have a 1997 mk1 MX5 1.8 which I use as fast road/track car. I recently did a trackday at Castle Combe and it seems afterwards that the brakes aren't as good. I went out in it this afternoon and under heavy braking the pedal travel is much longer than it was prior to the trackday (implying that the fluid has boiled?) and is a lot harder to lock the wheels up than before the trackday. When stationary, the pedal is still firm (though yet again, not quite as firm as before). It's all safe and does stop at a good rate, just the pedal travel is longer than expected. What I don't understand is how I'm boiling ATE fluid on track? Fresh ATE was put in before the trackday (which was purchased a few days before) so I don't think it's because the fluid had got water in it. I'm aware that it's not the best fluid in the world but I thought it would be able to cope with 6x 20 minute sessions. Has anyone else had bad experiences with ATE fluid? Have others boiled ATE fluid? It's only a light car so I wouldn't have expected it would boil but it looks like it has. Think I might try Motul RBF600 next..

[E-bmw]

Have used it for several years on much heavier cars without the slightest hint of over cooking the fluid.

[Redline88]

Is it possible that you’ve maybe got a very small leak somewhere on the system?

[MRichards99]

Redline88 said:

Is it possible that you’ve maybe got a very small leak somewhere on the system?

Perhaps, I've had this problem for quite a few months and bleeding the system with another litre of ATE (sometimes bleeding it, doing 50/60 miles then bleeding again to remove any remaining air) does the trick but the problem seems to come back after a trackday. I did notice that after the trackday the fluid was down a tad, but I put that down to the caliper pistons being pushed in more because the brake pads had woren? I've checked the brake lines and the connections have no leaks if I put my finger round them, the brake lines that run from the front to the back all look good, couldn't see any visible leaks. Are there any other obscure places I might be missing?

[thebraketester]

I think Castrol SRF has the best spec when I looked a few years ago. Eye-wateringly expensive however.

[nickfrog]

RBF600 is difficult to beat for value and longevity. I never managed to cook it in the Megane.

[veehexx]

I'm running the ATE in mine right now (fk2 typeR). last event i cooked pads, dust seals and got discs over 630c. 2nd time out on track with same fluid and no issues. is it possible you've cooked the pads?
i've RBF600 waiting for next change though but probably not till next spring but that was just because i threw it on a recent order as i thought i didn't have enough ATE fluid.

[Humour]

Im experiencing a similar issue on track and Im using ATE but I suspect the issue isn't only fluid related.

In my case the braking system has been heavily revised using a twin MC setup and no booster. Larger than oem front disks with a proper cooling duct solution into the hubs in the front axle. Have measured temps in the 500-600c without a cool down lap and 200-250c with a cool down lap with an IR gun. Rear axle also has cooling ducts but quite elementary only reaching the inner face of the disk. The usual stainless flexi lines in both axles and std. Calipers running CL6/5+ pads.

In my case the pedal is rock solid for the first session (20-30mins) then gains about an inch of travel and stabilises from that point on. Does it every time no matter if new or used fluid, pads, discs. Obviously more pronounced when the pads are near the end of their life but very noticeable anyway.

Im still trying to figure out if the bias box, or bulkhead is flexing too much when it gets hot, or the ABS pump which is still attached is a contributing factor, difficult to ascertain thats for sure.

Edited by Humour on Monday 17th June 21:16

[MRichards99]

veehexx said:

I'm running the ATE in mine right now (fk2 typeR). last event i cooked pads, dust seals and got discs over 630c. 2nd time out on track with same fluid and no issues. is it possible you've cooked the pads?
i've RBF600 waiting for next change though but probably not till next spring but that was just because i threw it on a recent order as i thought i didn't have enough ATE fluid.

Yeah I definitely got the pads pretty hot! I replaced them with Euro Parts specials (Eicher) for the time being (and roughed up the discs to remove old pad deposits and remove most of the scoring) and the braking performance is better (the pads and discs now have some bite) but the wheels struggle to lock (pedal travel is quite long when I attempt it, though when stationary, pedal still feels quite firm). Got some RBF 600 on order so going to see what that's like. I don't think the amount the pads were glazed helped matters in terms of brake fluid temperature...

[Humour]

MRichards99 said:

Yeah I definitely got the pads pretty hot!

Typically overheated pads will wear prematurely, crack significantly and in some cases separate from the backing plates un pieces.

Other indicators are if the surface of your disks start turning blue/purple (ish). That typically means disks are exceeding their heat transfer capacity. Which means they are overheating and so will the pads as a result.

[nickfrog]

True. Too much heat means that the bonding agent that holds the pad together starts melting and seeping out and there is nothing left to keep it in one piece. The damage and wear rate is exponential too, brakes need cooling off before they reach overheating, however frequent that is.

[Cardo]

Have a look at your pads to see if they've tapered.MX5 calipers flex a lot when using them really hard on track.This leads to uneven wear on the pads and can result in a long pedal and poor braking performance when used normally afterwards.

[Paul_M3]

If you look at all the specs, Gulf RF1000 is very hard to beat in the boiling point / £ stakes.

In fact from memory I’m not sure anything else has a higher dry boiling point.

[MRichards99]

Cardo said:

Have a look at your pads to see if they've tapered.MX5 calipers flex a lot when using them really hard on track.This leads to uneven wear on the pads and can result in a long pedal and poor braking performance when used normally afterwards.

How would you prevent the flex in the caliper? The Mintex 1144 pads I used on the trackday were pretty glazed so I've put a spare set of cheapo pads in for the moment just for road use (waiting for some Roddision pads). All calipers have been replaced with aftermarket units (all from Autolink) so hopefully they're not at fault.

[Cardo]

MRichards99 said:

Cardo said:

Have a look at your pads to see if they've tapered.MX5 calipers flex a lot when using them really hard on track.This leads to uneven wear on the pads and can result in a long pedal and poor braking performance when used normally afterwards.

How would you prevent the flex in the caliper? The Mintex 1144 pads I used on the trackday were pretty glazed so I've put a spare set of cheapo pads in for the moment just for road use (waiting for some Roddision pads). All calipers have been replaced with aftermarket units (all from Autolink) so hopefully they're not at fault.

There's not much you can do apart from change the calipers from a floating single piston to some aftermarket 4 pots.
There'll be nothing wrong with your autolink calipers,they're just getting used a lot harder than they ever would on a road car.
If you get a mate to really stand on the brake pedal you'll see how much flex there is at the calipers mount.

[nickfrog]

Paul_M3 said:

Gulf RF1000 is very hard to beat in the boiling point / £ stakes.

In fact from memory I’m not sure anything else has a higher dry boiling point.

Thanks for the tip, never heard of it but higher boiling point than the RBF600 indeed - will give it a go later this year and see if I can cook it at Snet !