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E1EXG

Alcon rear discs

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Hi all 

Any one used Alcon rear discs ? & have views on theme 

Thinking about a Seriously Lotus 288m/m rear set 

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considered them, but went with AP (308mm) and Seriously Lotus floating bells in the end. this is on an S1 elise, using 4 pot calipers at front and the 2 pot AP calipers from the front on the rear. Not a track car.

elise brakes front right 1.jpg

elise discs rear 3.jpg

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Yes, used them on a couple of builds, no problems and have just fit a set to a 2-11. They work and fit well with the std calipers. I'm a bit of a fanny when it comes to "looks", has to be balanced and look right. They are about the only 2piece rear disc/ bell combo you can buy that you can get a set of fronts that match in appearance(I'm talking about the grooves cut into the face). I'm using Alcon 295 front, 288 rear, std calipers.

IMG_20171219_1805062.thumb.jpg.24128d76b0d20ead59e3d4f1df5b01d8.jpg

 

 

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1 hour ago, stratosboy said:

considered them, but went with AP (308mm) and Seriously Lotus floating bells in the end. this is on an S1 elise, using 4 pot calipers at front and the 2 pot AP calipers from the front on the rear. Not a track car.

elise brakes front right 1.jpg

elise discs rear 3.jpg

Looks nice and tidy! Think I've got a gear mech sitting here for you thru Stu unless I'm somewhat mistaken??

Personally with that set up, I'd look to run another set of the 2 pots upfront instead of the caparo 4pots. The caparo calipers were  designed to work on a disc with a narrower face, you can see in the first picture you've posted that you have about 5-8mm of upswept disc face on the inside where the pad doesn't run down to the edge of the disc. That's obviously lost performance in terms of the disc itself but it can also (in extreme cases) cause the disc to crack in a violent fashion due to the difference in thermal expansion across the disc face. The disc wants to be heated up evenly across its entire width, applying the brakes puts a lot of heat into the disc very quickly, if the inside of the disc is not being touched by the pad then it runs much cooler than the outside where the pad does touch. I've seen it happen on more than one occasion, but to be fair they had probably about 10-12mm of upswept disc face showing. By rights the pad should sit on the disc with about 1mm of disc face still showing on the inner and outer edge of the pad.

If you look at the 2nd pic of the same disc but with the 2pot sitting over it, the pad sits much nicer on the disc as it runs further down covering more area.

The overall size of the pistons in the 2pot and the 4pot caparo's are not far off each other in terms of surface area being applied upon, the 2pots have 2 large pistons, the 4pots 4 much smaller ones, no change to master cylinder is require between the two. The 4 pots do have a larger pad surface area over the 2pot pads but given the choice, id rather have 100% of the disc face covered by a smaller pad than 85% of the disc face cover by a slightly larger one. I don't believe you'll lose any braking force over the 4's using the 2pots upfront and it will have a much nicer finished look to the car being the same front and rear (the fanny in me again....).

 

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cheers Gav, appreciate your advice, hadn't considered this.

Do you think it matters that much on a non track car? - I will be using this for the road primarily, with lots of times tootling between blasts. so discs will have plenty of time to cool again. I know they might be a bit clacky - noisy.

Yes I have been negotiating with Stu from Scottish Elises to buy his 211 gear linkage, so it's with you now is it? - I've just sent him a message asking for an update.

is it all back together again and working ok? - this is going into this S1 elise project with VAG engine.

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It will work okay if for road use only, I doubt you'll spank them enough for them to destroy themselves. The two times I've seen it happen have both been on 308 discs using the 4pot calipers that were used originally used on the S1 Motorsport cars with a AP 295 disc. It left about 10+mm of upswept area on the inside of the disc face simply because the caliper was far too small for the size of disc being used. The ones I physically saw were brand new discs and had only done a couple of track sessions that day when they went, they had cracked (and I mean right the way through!!) from the outside edge of the disc and it stopped Exactly where the inside edge of the pad had ran up to. Obviously the outer part of the dics has got hot much quicker than the inside,  it has wanted to expand but the inner rim of disc still cold has said f++k you!! 

Again for a road car, I'd have to go for the beauty aspect over outright performance. Another set of the 2 pots in the same finish as you have on the rears would just make the car look right when viewed from the side on at a distance, at the minute you have black calipers up front and silver rear. Going into the closer detail you see (well I would anyway) that  the caliper sits nicely over the disc and it's a good marriage between disc and pad. When in use the majority of disc face will always be kept clean from rust as the pad runs on most of it. The upswept area of disc you have now with the caparo will go rusty in no time at all and will look a bit, well, it will look a bit, you know! But that's just me in all fairness...

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would a deeper pad help? if I can get one,,,,sorry to E1EXG the OP, for the thread drift - but this is all good brake info stuff.

you can tell I'm a bit resistive to give up my new Caparo's easily. I get what you say about the overall aesthetics though.

 

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Dave

Is there a reason that the bolts holding the discs onto the bells have the nuts on the outside on the rear discs???

They should be the other way round like the fronts

 

Re the caparo pads, there are a couple or three different depth pads available, cant see which ones you have there, sorry

Edited by Seriouslylotus

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Thanks Dave,

I realised after I'd bolted the first one (rear) that the bolts needed to be reversed (but there were examples bolted like this on line too). I've changed them now.

Appreciate your advice re: Caparo pads, do you know what they are? and where I might get a deeper pad from. I'll measure the ones I've got later and post on here (sorry again OP).

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