Anyone know why the factory didn’t open these on the Exiges? Any pro’s cons to know about?
Carttman
They were put in by the stylists of the Motorsport Elise just in case they were needed. At first, the motorsport team didn’t even bother opening them for the race cars.
They certainly aren’t needed for road use on the Exige.
I know a number of people have opened theirs. Maybe they can tell us whether they have any trouble getting their brakes up to temperature in day to day road use?
I’ve been thinking about doing this too…
Uldis has a load of info on them, about opening the middle of you brake hubs so air flows out.
He also made some mould to go in there but I don’t know if this:
http://www.demon-tweeks.co.uk/catalogue/product_detail.asp?PCODE=SAMSFD-031&GRP=MP109&PGRP=M008&CLS=MSPORT&code=SAMSFD&from=search
Would be just as suitable?
Had a search Udlis’ ducts but not found 'em
Would say that with road use and standard pads it would not really be necessary to open them up, the blacked out bits are different sizes l and r, so if you do decide to run some ducting be prepared for some fabricating. I have run some ducting to the wheelarch from the front ducts, cutting some round bumper ducts to fit into the holes. That is for track use though and would not really bother for general road use as it does not look as nice as the fake ones unless you can mould fibreglass and do a really decent job. Then you also need to make a cover for the cold rainy days. Just replace your brake fluid with srf and you will have a much higher boiling point and it should not be necessary to open them up.
Jason, Carttman,
check out this thread , we talk about it in depth:
Check out specially the Bokkatrack picture gallery on page 2.
I am fairly heavy on the brakes (late and hard), so the stock setup just wouldn’t do. After 2 warranty disk and pad replacement I decided to go my own way and have arrived to something that works.
Also, this winter will go for the final iteration of the brake mods and install my own design of twin brake master cylinders.
But let’s say, you only need this mod if your setup is currently a limitation.
Also, this winter will go for the final iteration of the brake mods and install my own design of twin brake master cylinders.
I assume this will be with abias bar between the two
Exactly.
There are a couple of guys selling complete pedal boxes with twin master cyls, (Plans and Kelvedon for those of you who want to go that way) but I feel I could do a very simple one, using most of the existing setup.
All the mods I’m doing are with a view of making the stock items work whenever possible, and I truly believe that the original calipers are up to the work, it’s just that the braking bias is wrong, and after talking to some Lotus guy (don’t remember who but he works now at the Motorsports dept) it was due to parts availability, that rear caliper is the one that more closely approximated the design parameters. Couldnt find any other that displaced slightly more fluid, either this or too much more.
Just needs a balance bar.
Check out specially the Bokkatrack picture gallery on page 2
Thanks Uldis had checked that out before when i was researching opening them up, i however do not have the fibreglass expertise to make the ducts quite as well as that. I just put the ducting for a bit of general cold air flow, they might not be of much use but will be better than none at all.
In a year of racing, average of 30km per race i never experienced brake fade using pagids, and running on slicks the brakes were in my opinion providing quite enough stopping power. And no i wasn’t going slowly, 5th behind 2 porsche gt3 supercups, a 993 gt2 le mans car, and a race tvr. Do you find that with your brake upgrades you have improved braking power or consistency. Be it consistency i quite agree. Have ordered the Lotus sport 4 piston calipers for the front, as we will be entering the endurance series next year and require consistency over a long period. I have taken the larger master cylinder and brake bias valve to get the job done properly. And depending on performance over 3 hours would look at doing a proper job for front and rear cooling. Granted the standard disks will not stand up to a year of endurance and series racing, but i consider them a consumeable part at the moment and budget on replacing them twice a year. Have been looking around for around for some other discs, perhaps AP or wilwood, but need to get around to the local guy who makes bells to see which will be the most cost effective solution. However after being quoted 1200 pounds per corner from the AP agent for calipers that fit and paying 350 pounds each for the lotus products i’d rather continue to replace discs without re engineering the whole system and still save money. The 4 pistons are going to give more feel and hopefully extended performance time.
Everyone however has different styles of driving and ambient temperature, track etc all effect how hot or not the bakes will get. And should they be overheating you would definitely need a decent setup for venting from the inside of the disc, as well as providing a cool air inlet in the front of the wheelarch and a hot air exit at the back of the wheelarch over and above, far to much engineering for me.
The moulded vents are great if only i could work with fibreglass mine look quite s**t compared, ok very.
PLease don’t take offence i don’t mean anything in a funny manner if perhaps it sounds that way. what i meant in my first reply was if you need to open them up then by all means but if it’s only for road use rather leave them be.
No problem at all, this has been my experience and really, I want to keep the car as original as possible and if I modify something is because its limits were reached.
Now, I don’t have that much of fiberglass experience but I had some extra time in my hands and decided to give it a shot.
Unfortunately I haven’t been able to do more, but will eventually.
On the first iteraction I did what you describe though, of dumping the cold air in the wheel well, with no results.
On the second one I routed the hose to the side of the caliper, thinking that it would cool it better, no results other than getting everything dirty in there! You wouldn’t believe the amount of sand, grit, dust and plain shite that went in the caliper and disk. I studied then some of the racing setups and realized that the only way was venting through the vanes of the disk.
For this you need closed alloy bells and a special shielding on the back, so all the air is used to cool.
The result is complete stability with no overheating. To answer your question precisely is consistency. No fade.
Now, the 4 pot setup and 2 pot in the rear is the best setup, but it’s very expensive, and not road legal, as it loses the handbrake. Also, I’m not sure it’s that much better that an well sorted setup like I’m doing.
But the fact is thatm the bigger the friction area, the less work the pad material has to do locally, therefore, less chance of overworking them, therefore less chance of overheating.
But you lose the handbrake.
And in your case I agree with your caliper choice, if I understand well, 4 pistons at the front and the front 2 pistons to the back with either a balance bar or limiting valve.
But definitely for more stopping power you need to give more power to the rear and more work dissipation to the front.
I can’t imagine though why AP is quoting �1200 per corner! Last time I called them it was more like �250 per caliper (don’t really remember, but it didn’t reach �400)
I wouldn’t use the Lotus MS disks though, go for AP, they’ll be cheaper (including the bells) than the Lotus ones, and the venting is in the correct place.
One thing, there is a natural low pressure area on the outside of the wheel, and yes, also at the rear of the wheel arch, but air that has cooled the disks will not be extracted at the rear of the arches. That one could be used to extract other hot air from the front area in the case you didn’t have wheel liners.
Venting from the inside (shield and closed bells) just uses this natural air extraction.
Go for it, but call AP directly first.
Uldis it seems we are both going in exactly the same way, i also do not want to lose the handbrake so am going to use the bias valve, and the 4 pots are for greater area less work more consistency. So we are on the same page
Apparently the calipers were of the solid billet variety hence the price, but the lotus 4 pots are ap anyway so no need to re invent the wheel there at that price. Will investigate the discs in the near future when the calipers have arrived.
Incidently our agent called AP while i was there and they have had several enquiries and are working on a kit for the elise/exige, which will bolt straight on and hopefully inlcude discs.
Will post the part number for discs and bells when i find them, think i have found the right willwood bells but won’t post until i am sure.
Jason, have you seen the AP disks that Uldis found?
I had a look at the Wilwood site and they don’t appear to do a 1" width disk, and their 11.75" dia. (298.5mm) is probably getting close to the maximum amount of spacers you’d want to put inbetween the hub and caliper (that is unless the motorsport calipers are designed for those width disks?).
I’m still interested in getting some hubs (or hats as Wilwood appear to call them) for the AP format. I’ll get round to it one day.
Ian
Although I have just done the maths on the CP3124-894/5 and it doesn’t seem to add up. The wall thicknesses and airgap don’t make the claimed overall thinkness?
The CP3580-2894/5 seems okay though.
Ian
Thanks Ian,
The CP3124-894/5 has the correct disc thickness, perhaps its just the size of machining at the airgap, not sure but as long as the thickness is right. Also could be that the friction surface is thicker hence reducing the airgap.
The Cp3580-2894/5 has been superceded by another part number but AP has no stock at the moment of the new part.
I have ordered the 3124 for the fronts as a preemptive strike while my current discs wear down it gives me time to get some bells made up and the fit the 4 pistons with bigger discs in one go. Perhaps if there are some other people who want bells we can do a group purchase, but over the pond will cost a fortune, will let you know roughly.
Ian, the measurements are ok.
Besides, there is no data on the wall thickness.
Perhaps you’re taking H, the flange thickness as the wall thickness? they’re not the same, this measurement is only the attaching point to the bell, which is easily different from the wall thickness.
Anyway, the one with the bigger airgap is what you want.
Uldis it seems we are both going in exactly the same way, i also do not want to lose the handbrake so am going to use the bias valve, and the 4 pots are for greater area less work more consistency. So we are on the same page
Oh oh, I see a flaw in your plan.
If you don’t want to lose the handbrake you should not go for a bigger friction area in the front, as the only thing you’ll do is diminish the overall braking power.
Yes, the fronts will have to do less work per sq/mm, but they are going to do MORE work overall, bringing the bias to the front. This is why if you fit 4 pots in the front, you should fit the front 2 pots to the rear, so as to bring the rear braking force up.
But then you lose the handbrake.
The thing is that the bias valve is just a pressure-limiting valve, it will not increase pressure, but diminish it to the rear circuit.
And common practice says you should not use a pressure limiting valve to the front circuit because you will get an inconsistent feel and for safety reasons.
If going 4 pots at the front, go 2 pots at rear, and you can use a bias valve (but better yet a balance bar if you can, for the feeling alone)
If resorting to use the stock calipers (handbrake), you need a balance bar because the rear just needs a bit more pressure, it’s not far off. But each caliper will end up doing more work (than the 4 pot/2 pot choice), so unless you have a good cooling system you risk going over their limit.
You could get the stock calipers to work ok, in fact his is the route I’m taking, but compared to the 4 pot/2 pot you will always make the (smaller) pads work more, therefore heat/wear quicker.
Controlling temperature you control the heating part, but they will wear quicker than the 4/2 setup.
Ah, another thing, you don’t really NEED a vented cooling system in the rear. It would be good to have, but not really needed, as the heavier you brake, the less work the rears do (weight transfer). If anything, some ducting towards the area would be ok, no shielding.
I can imagine you would need shielding if you already have 4 pots front, 2 pots rear, big ducting front and real downforce. If you then feel rear brake fade, then you duct.
What about , shot in the dark here, a hydraulic handbrake setup for the rear when using the front calipers at the back. Alternatively a smaller caliper as a handrake at the rear, but then unsprung weight goes up again and you end up going backwards as far as weight issues go.
Gonna see what i can do about the handbrake situation as i do not want to have 2 pots that fit on the back lying around doing nothing
Bias valve would only be useful if you had to much force in the back which is not gonna happen with the standard rears.
…i’d rather continue to replace discs without re engineering the whole system and still save money.
I read again you rpost and thought of passing on a comment made by one of the Lotus engineers working on the Autobytel series (can’t remember his name, but he knows his stuff). The MS didk you’re talking about came in different sizes through the series, ending in 295mm if I’m not mistaken, but there were several sizes throughout.
Still, they were still shite, and some wanted to go for something better, but as these were the regulations, they stuck with them.
Besides, they were cheap, so as soon as they warped or gave problems, new disks were on.
The brake bias valve was another example, though not as bad. They wanted the balance bar but the pressure limiting valve was simpler/cheaper.
So, to say there was not a lot of engineering there, mainly cost control.
(Hint, is using a pressure limiting valve, choose the turn-screw type, not the lever type. More linear)
What about , shot in the dark here, a hydraulic handbrake setup for the rear when using the front calipers at the back. Alternatively a smaller caliper as a handrake at the rear, but then unsprung weight goes up again and you end up going backwards as far as weight issues go.
Gonna see what i can do about the handbrake situation as i do not want to have 2 pots that fit on the back lying around doing nothing
Bias valve would only be useful if you had to much force in the back which is not gonna happen with the standard rears.
If you can get by using hydraulic rear handbrake, you can use the same 2 pots at the rear as a handbrake, just fit a hydraulic locking valve.
You press the brake pedal hard, turn the hydraulic lock valve and release the brake. That way the rear pistons are pressed and you have a handbrake.
This is, however not road legal here, but if it’s over there…
OTOH, you still have to be careful of not using it after tracking it, as you can still cook the pads or boil the fluid after a session.
Maybe in that case a smaller separate cable operated one would be better. But it’s extra unsprung weight…
All these complications are why some people just forget about handbrake on race cars…
Reading through this, why could you not have a really small seperate calliper as the rear hand brake?
Is it just the extra weight?
Well, yes, mainly that, the extra weight of the caliper and bracket needed.
Not that 1 Kg extra would be that bad, it’s the fact that it’s in the wrong place, unsprung weight.
If I could find a really small one I would be tempted to go that way as well.
I looked into the Wilwood ones but couldn’t find a good one.
Let me know if you find a good one.