Warped iron discs on a S1 Elise

[Mike.Mc]

Hi. I'm new to the forum and have been browsing the pages to find and answer to my problems.

I have a S1 Elise Sport 135 which comes fitted with the cross-drilled iron discs as fitted standard to the S1 Exige and other Sport Elises.

 

My problem arises on track days at Castle Combe. At the 2012 Club Lotus day I managed to warp my front and rear discs. They were admittedly old and worn so this year I returned with new discs all round, new Brembo Sport pads, Castrol SRF brake fluid and the already fitted Goodridge SS braided hoses.

 

After running everything in for a couple hundred miles prior to the track day all seemed well. Yet yesterday at Combe (25/05/13) I started to feel the tell-tale signs after 7 laps. Even when my girlfriend ventured out for her first track driving experience after I had let the car cool it was still noticeable after a few laps when brake temperatures increased. When I went back out in the afternoon 4 laps was enough to throw the towel in. I pulled a front wheel off and you could see the hot spots on the disc with a lot of blueing even inside the webs.

 

The orange S3 Elise S which was impressively hammered around all day by Dan from Lotus suffered no such problems on it's standard brakes so I'm at a loose end really.. I am admittedly a little hard on the car and the Yoko A048s allow heavier braking but I'm sure they should survive a lot better!

 

Any advice would be hugely appreciated.

Mike.

[Bentzion]

When you expose a single piece cast iron disk to extreme temps it tends to warp.  That is why in racing they use a two piece (usually curved vein) rotor.  That being said, your choice in pads may be a bit aggressive for the stock rotors, maybe.  Your calipers MAY need rebuilding as well.  You want the piston in the caliper to retract when you release the pedal but as the temps rise you may be experiencing some sticking.  Oh and DO NOT use silicon based fluids!  It has several totally unacceptable characteristics for auto racing. Silicone expands at elevated temperatures, which causes a spongy pedal. This expansion can be so severe that total system brake lockup can result. Some silicone fluids can attack seals in your system, stay with Dot 3, 4, or 5.1 fluids. Try to buy a fluid that is rated at 600deg + dry.  I recommend you flush a fresh bottle of brake fluid after each racing event you attend. One bottle of fluid before the event will give you a great brake pedal all day, and bleeding the system at each caliper after the event removes the fluid that has seen the most heat during the event [near the caliper and rotor] and replaces it with fresh fluid

 

 

 

Full disclosure:  I am in the braking industry and I may have solutions that will work on a stock style rotor but only if you follow some of the advise above (rebuild calipers and stop using silicon brake fluid) You can contact me by PM if you like. 

 

Hope this helped a bit.

Edited May 26, 2013 by Bentzion

[Bibs]

Top response

[ramjet]

Welcome to TLF Mike Mc.

 

Duck over to the Introductions thread and say hi in there as well.

[Mike.Mc]

Hello Ramjet and sorry for missing the Introductions thread, I will on there straight after.

 

A massive thank you for your time Bentzion for your time and advice. I will also PM you later.

 

Regarding your feedback, I do use the two piece (sandwich) discs which measure about an inch wide. I believe they are Lotus Part Number: A111J0141F. I was surprised they managed to get quite so hot with such a large cooling void in the middle for such a light car. http://wiki.seloc.org/images/2/22/A111J0141F.JPG

 

Pad wise I wasn't sure what to go for and the advice from many was varied. The stock pads that were fitted to the car new I found quite good actually. After that I was suggested to try some of the EBC range but I found them to be quite poor. Not great in the cold, bad squeal, accelerated disc wear and when used hard they over heated and glazed both pad face and discs. To be blunt, I found that a lot of advice comes from people that might not venture onto the track where the brakes receive punishment the public road will never provide! I then tried the standard Brembo pads which were a huge all round improvement. Last year at Combe, when I had similar problems, I thought I just used the pads outside of their intended use so went for Brembo's Sport range as full race pads would be over the top for me.http://www.eliseparts.com/products/show/22/1150/brembo-hp-sport-brake-pads/

Up until Combe I found them to be spot on and I'm not pointing the finger at them to be the cause of the problem either but I'm open to suggestions for different ones to try.

 

I'm going to buy all relevant parts to rebuild all four calipers as they have never been done and will replace the fluid with a 5.1 variant then. I tried the Castrol SRF from recommendations and saw it on Elise Parts and other sites with a glowing write ups. My clutch slave cylinder failed recently so that might have been the fluid attacking those seals. http://www.eliseparts.com/products/show/23/14/castrol-srf-brake-fluid/

 

Basically I don't want to have to needlessly upgrade the brakes as I'm sure their ability is greater than mine when everything is working as it should, but if that is what's needed then again, I'm open to ideas! After the drive with the Lotus test driver in a standard Elise I was totally impressed with the factory standard set-up and considering it was on the track more often than not from 9am to 5pm it was still going (and stopping) strong.

 

Once again, thank you for your time and advice and until it's sorted I'll just carry on banging my head against the wall.  

 

Cheers, Mike.

[Bentzion]

Mike,

 

The rotors you are referring to are what I speak of as a one piece rotor.  The two piece is :

Where the hub is bolted on.  As you can see from the photo above. As well the the rotor in the picture on the elise parts link you pasted for the pads.  If you go that route DO NOT GET floating hub rotors.  Strictly two piece

 

The best thing to do is to call a "real racing" distributor and tell them what your running as a kit and someone with knowledge should be able to point you towards the right product.  Racing pads are a whole different breed.  They can be noisy and very dusty but their temp rating are very different from a street pad.  I would suggest you swap pads for the track and you will enjoy them tremendously! 

Good advise should come from a pro who does the business day in day out. 

 

I would like to add that your ability to brake is just as important you ability to accelerate.  Most people spend many thousands to obtain more horsepower yet a great brake system will allow you to CONSISTENTLY brake hard into a corner and when the pedal is released not drag a single wheel that may upset the handling balance and not drag on the way out of the corner.  That is cheap horsepower and speed compared to building an entire motor. 

 

Sooo... when getting the calipers rebuilt find a good machine shop that can measure the caliper body and see if the piston cavity is nice and round as well as the piston.  Just like a motor's piston, if they fit well together you get less resistance and better reaction from the brake system.  If they find that they are not, buy new.  In England you have a great many resources in motorsport.  I'm sure you can find someone who can help.  As before you can PM me and I'll try to help where I can. 

Bentzion

 

P.S.  You don't need drilled rotors.  That is something that has not been needed for years with good "baked" or "out-gassed" pads.  The slots cant hurt.

[Mike.Mc]

Again, thanks for the replies everyone and the PM's Bentzion. Based on advice I have decided to upgrade to the two-piece discs from Elise Parts, matched with my existing new Brembo Sport pads, renew master cylinder and will replace the fluid for AP's own best DOT 4 fluid.

Also I will be checking and rebuilding the calipers. Which presents me with the opportunity to have a little switch around! I think the front AP calipers are a cracking bit of kit, but the rears seem a little under powered and awkward with the combined handbrake when it comes to swapping pads out compared to the fronts. (Only my opinion)

I could either rebuild existing calipers with above mentioned parts.

Or replace rear calipers with matching AP front ones with available conversion bracket. Change handbrake to a hydraulic one with ratchet mechanism and fit to match standard one. Plumb the brake line from master cylinder on pedal, through a bias valve, through handbrake master cylinder and split to rear calipers (Same as my 205 rally car). I would of thought that would provide me with a base 50/50 brake split and adjustment to increase bias to front, a better handbrake when needed and the same pads all round that can be changed much easier during an event as calipers stay in place. If I wanted to increase disc diameter I would only need to make eight matching spacers to raise calipers. Also I can ditch the handbrake cables!

Has anyone tried this? Would be quite affordable by sourcing the parts on eBay and I don't like the idea of throwing money at big fancy calipers when the standard AP parts should do me fine!

Your advice would be appreciated again. Cheers, Mike.

[Bentzion]

You could see up to 30% increase in brake capacity by choosing the correct pads the Brembo street pads are made by Jurid (not great pads.)  Their track motorsport stuff is made by them.  Most people dont want to get rid of their standard e-brake.  But by doing so many options are available to you with the rear set up.  The standard AP stuff is great for the occasional track day!  Good luck!

Edited June 5, 2013 by Bentzion

[Mike.Mc]

I wish I spent some more time researching pad choice before I forked out for the Brembo ones! I haven't had any problems with them and they've only been on the car for 400 miles and half of that was up the motorway and back for the track day!

Going by a few suggestions for a good fast road/track day choice and with reference to http://wiki.seloc.org/a/Brake_pads I think the Pagid RS 4-2 Blue, or Mintex 1144 would be a good choice. They also are recommended for my future discs.

With regards to the calipers, I like the idea of the APs all round unless there is a good reason why not. Especially as I can add in the parking brake. With the available bias adjustment I could add slightly more to the rear, and a little more again for the wet.

And I guess another plus would be taking advantage of the quick pad change with calipers in place. I could swap for more aggressive track pads at an event easily, then back to road pads for the trip home!

Thanks, Mike.

[Bibs]

I'm sure Lotus were selling the Elise AP calipers off cheap in a parts sale not so long ago...

[Mike.Mc]

Typical.. Who were they sold through?

[Bibs]

Any dealer would be able to supply them if they're still available.

[gt111]

Before throwing too much money at this problem I would try another set of pads - give Pagid RS14 or RS4-2 ago.

 

I'm running Pagid plain discs with CL RC5+ pads, SRF fluid (although I haven't had any issues with SRF fluid I wont be getting it again as its too expensive and doesn't last very long) and the standard calipers and do not have any issues on road or track with really good performance.

 

If you want to change your rear brake balance you can put different compound pads in the back. i.e for CL use RC5 front RC6 rear, for Pagid RS14 front and RS15 rear might work?

 

Most people that have stuck the AP's on the back have put 4 pot big brake kits on the front.

[jimbo2]

Brake fade & disc warping.

 

General rules for looking after your brakes on track days include:

Always do a cooling down lap at the end of  session, medium speed, minimum use of brakes. Park in gear with the handbrake off & let the car roll slightly on stopping so the pads release properly. If you can be bothered, roll the car a foot every 5 minutes until the brakes have fully cooled.

Braking later and firmer than you would on the road reduces heat build up – breaking gentler & longer is not good on track.

Discs – AP racing are obviously the ultimate but I have just replaced Ultimax Turbo rear discs (EliseParts) on my S1 after an amazing 40,000 miles including lots of track days. I’m not a fan of drilled discs (apart from cracking, they only improve cooling if you routinely clean out the holes which is quite tedious).

Pads – lots of personal preference & I’ve tried most. An excellent compromise for working from cold on road & being good on track with good feel & bite is Carbone Lorraine RC5+. And bed any pads in properly. My opinion of EBC pads is not really printable. Mintex are very hard on discs & lots of brake dust. Pagid are excellent but noisy & hard.

Calipers. The standard calipers are fine & well balanced, especially the rears with a powerful  handbrake – sticking cables are common but easy to change. Fitting adjustable brake bias isn’t necessary & just gives another variable to add to the confusion.

As ever this is my personal opinion but based on tens of thousands of track miles.

[Mike.Mc]

Thanks again for the advice as it's been a great guide!

 

I MOT'd the car yesterday and had a play on the brake tester. No problems and passed the brake test with flying colours! 93% brake efficiency which would have be more if the car didn't jump out of the test rollers! Different story when at the track though..

 

During a track-day, especially the last one, I was trying to be kind to the brakes by using the first lap as warm up for the brakes and tyres before engaging warp drive. I am quite a 'late-braker' and was always impressed with the previous stopping power with the car especially after fitting the A048 tyres. My favourite part of Combe is seeing how late you can brake after the Avon Rise leading into Quarry! 125+mph to I guess 60-70mph during a slight left heading towards a barrier certainly raises the pulse!

It was the feeling of doing the above on a cobbled stone road that put a stop to my track duties that day, and my pants use by date.

 

After the chequered flag I do a 60-70mph cool down lap in 5th gear without touching the brakes. Once in the paddock I leave the car in gear with the handbrake off but must admit I do not move the car every now and again whilst not in use.

 

As GT111 said, I don't want to spend unnecessary money on the brakes especially when it could just be a simple and affordable fix. I've put the idea of using another pair of AP calipers on the rear to bed as I found out that a hydraulic handbrake is illegal for road use if it is the only parking brake available. There has to be a mechanical handbrake in place. So, I will now just rebuild my existing calipers, replace my aging master cylinder, fresh DOT 4 fluid and replace front discs.

 

One thing I would like some past experience on is between my two disc options. Either Elise Parts own two-piece discs http://www.eliseparts.com/products/show/21/1/aluminium-belled-discs-s1/ for £300 inc. VAT a pair.

Or the cars original Lotus Motorsport discs which have now been superseded by a grooved design for £266 inc. VAT a pair. I like the idea of a two-piece disc but worry about the quality of the steel rotor considering the AP discs are £642 a pair. I also prefer grooved discs as opposed to drilled even though I have never experienced cracking with the Lotus Motorsport OE drilled ones. I am happy to see they have switched to grooved though!

 

Finally I have now, with your help  , narrowed my pad choice down to either Carbone Lorraine RC5+ or Pagid RS42. I am starting to lean towards the CL RC5+ choice but again, I am basing my choices on others experience with them and online write-ups.

 

Thank you all again and hope you enjoy the sunny weekend. I'll be down Tregrehan Hill Climb and Car Show on Sunday so might see some of you there. If you see a silver Elise with blue brake discs, come and say hello!   

[Bibs]

If you want AP discs (or 2 piece bells/rotors) let me know. I know the company that make the castings for AP and they'll sell via us at considerable savings eg Esprit Sport350 discs at £600ish rather than £1800ish/pair.

[Mike.Mc]

Wow that is a saving and a half! If you wouldn't mind finding out a price for me that would be much appreciated! Both the two-piece and standard for a comparison please. Cheers, Mike.

[gt111]

I think your right to leave the Brembo's on the rear until you have tried new pads and discs, but just to say if you were thinking of putting the AP's at the back most people relocate the original Brembo caliper and use this just for the handbrake.

[jimbo2]

" I know the company that make the castings for AP" - the castings are only the start for good discs.
They then need to be machined, heat treated and most importantly, surface ground to achieve the correct "grain" in the metal - and that's not cheap.

[Bibs]

They do all that for them too! BG Developments.

[Mike.Mc]

Just thought I'd post a little update after all the advice I received.

I recently removed the calipers and flushed them all out, replaced all of the front caliper seals and rebuilt with new nipples and pad retainers, cleaned and regreased the rear caliper sliders and renewed pad retainers, reused the rear discs (about 1000 miles of use) and fitted the Elise Parts two-piece front discs, new set of Pagid RS14 pads, flushed brake and clutch lines out and refilled with Motul 660 DOT 4 racing fluid.

I drove up to Castle Combe and used my first session to bed the discs and pads in as per instructed by Pagid, then allowed to cool. My next session I brought everything up to temperature carefully then with fingers crossed worked them hard.. Success!! No juddering, heat spots, glazing or warped discs. Massive improvement indeed and especially during my later fast sessions. Everything has obviously gotten hot but has a nice even colouring with no dreaded heat spots.

When I have time I'll fully rebuild the rear calipers with the new seals I've already bought, but as my car has done little mileage and is dry stored for 6 months of the year the calipers were in remarkably good shape really. I would like to upgrade at some point as I still feel the rear is under braked, but for now I'm more than happy. My only slight moan would be the horrendous squealing from the pads during slow road use! It's like dragging your nails down a blackboard through a megaphone!

I'm not sure what was the actual fix but thanks again for the invaluable advice.

[Bentzion]

Ahhh The metalic pads squeal.....

 

That's a tough one.   The company I work with uses special thermal processes to abate some of the squealing.  When the pads a cold they squeal for the first two stops and then it ceases to happen...

 

The best solution is to swap the pads for street when not at the track.  That will allow you much longer life on your more expensive track pads and resolve the higher temp rated pad squealing.  Remember, you have to scuff the rotors when you do that as the different compound material left on the rotor may not play nice either way.  Also, it's better to give the pads a fresh surface to bite into.