Lotus Ap 2-pot Front Brake Conversion

[benlilly 0]

This came up in another topic so I thought I'd post some details here.

The AP Racing 2-pots as used on the Elise/Exige pop up on ebay quite a bit as owners uprate to the AP 4-pots for track use. This is where I found mine and decided to design a front braking system around them.

 

The calipers are quite a good match to a 205 GTi setup as the pistons are only a mm or so smaller than standard. When mounted on a larger disc, the braking force is increased and makes up for the force lost in piston area. I don't know how to do the exact calculations for this.

 

The calipers needed mounting a fair way inboard on custom brackets to clear my std 1.9Gi Speedlines. Alternatively, you can use wheel spacers. I didn't want to use spacers in order to preserve the suspension geometry. There is lots of info on this in one of the pinned suspension topics. The downside of not using spacers is that the choice of discs is resticted to rotors and custom bells which, obviously costs more.

 

The discs I used were from Elise Parts. They weren't too expensive and the disc was a perfect match to the pad area. Only downside was the weight.

 

The final system weighs 250g less that the std 1.9GTi front setup. If you wanted to better this you would need to use discs from a munufacturer such as AP racing or Alcons which, are expensive.

 

Here are some pictures:

[benlilly 0]

Here are the drawings for the parts I had made. PM me if you want other formats.

B. G. Developments in Bromsgrove took care of the manufacturing. Really good service and I'd recommend them to anyone needing any custom brake parts machining.

I'm no mechanical engineer and can't accept responsibility for any breakage or accident resulting from the use of these parts! If you want to use them, have a look over them and decide if you think they are up to scratch.

Having said that, I didn't skimp on material thickness and B. G. Developments seemed to think they were good.

 

Bell_and_Lotus___AP_Bracket_Drawings.pdf

 

Ben

Edited February 25, 2010 by benlilly

[custard-rallye 25]

any chance they would go under 106 rallye steelies the wider ones and how much roughly does it cost to get everything??

[swordfish210 20]

Looks really nice and looks like you've put a lot of thought in to it.

[welshpug 1,645]

possibly being blind, but I can only see the height of the bell and no total height or thickness of the disc?

 

does look good as mentioned, fitting them as far inboard as possible seems to be the key to get clearance from the centre of the wheel.

 

at 290mm dia I'd be surprised if they fit under a 14" rim, that's 11.4" without taking into account the caliper and the difference between the bead seat and the inner diameter of the wheel.

[Cameron 16]

Excellent work! And some pretty nice quality machining too.

 

What size rotors did you go for?

 

Oh and how much did the machining cost if you don't mind me asking?

Edited February 25, 2010 by Cameron

[benlilly 0]

any chance they would go under 106 rallye steelies the wider ones and how much roughly does it cost to get everything??

Hi Custard,

No idea if this setup would go under 106 Rallye steelies. Never looked at them up close. Based on clearance with the 1.9 Speedlines, I'd say no. I think you could get the AP 2-pots under the wheels though but you would need different brackets, bells, rotors.

 

Whole setup was about £550 but I haven't got the brake lines yet. Quite alot but by the time I'd done all the work, no turning back really.

 

Ben

[benlilly 0]

What size rotors did you go for?

 

Oh and how much did the machining cost if you don't mind me asking?

 

Hi Cameron,

 

Rotors are 288mm x 25mm

Bells were £80 +VAT. Brackets £85 +VAT. Both in anodised 6082 alloy.

 

Ben

[Tom Fenton 1,536]

Looks a really nice job Ben, I'm interested to hear what the braking performance is like when you have them on the car. What are pad prices like for the usual suspects uprated pads (Mintex 1144/Ferodo DS2500 etc)?

[benlilly 0]

Looks a really nice job Ben, I'm interested to hear what the braking performance is like when you have them on the car. What are pad prices like for the usual suspects uprated pads (Mintex 1144/Ferodo DS2500 etc)?

Hi Tom,

 

Me to! Need to put some hours in and get it finished.

 

About £60 for Mintex 1144's.

 

Ben

[craig_007 1]

Excellent write up there mate.

 

Craig

[benlilly 0]

possibly being blind, but I can only see the height of the bell and no total height or thickness of the disc?

 

does look good as mentioned, fitting them as far inboard as possible seems to be the key to get clearance from the centre of the wheel.

 

at 290mm dia I'd be surprised if they fit under a 14" rim, that's 11.4" without taking into account the caliper and the difference between the bead seat and the inner diameter of the wheel.

 

Hi Welshpug,

 

I haven't included the disc in any of the drawings. I'll add a few more drawings when I have time. I also have a simple 3D model of the hub which I can add to a drawing. This might be helpful to show offset between the hub face and the brake mounting points.

 

Ben

[Batfink 201]

great stuff. Any chance these could be used with smaller discs as I want to keep my 13" PTS wheels if possible.

[benlilly 0]

great stuff. Any chance these could be used with smaller discs as I want to keep my 13" PTS wheels if possible.

 

Can't see why not. Just need to come up with a mounting bracket to suit.

[craig_007 1]

I asked the same question regarding disc size and apparantly these calipers need a 25/26mm thick disc,I also wanted to use smaller discs but looks like I'll need to stick with the 283x26.

[welshpug 1,645]

just a few thinking aloud thoughts here;

 

I think you'd struggle to get them under a 13" wheel as a smaller diameter disc would necessitate placing the caliper a lot closer to the hub, this is the main area you'll have issues with wheel clearance.

 

To get around that you could offset the bell, but with a small disc like that you're quite limited (with a larger disc you can place them over the lower balljoint)

 

A 1.6 gti hub might actually be ideal for this due to the extra offset, otherwise using a wheel spacer to gain the clearance on the wheel would be necessary, using something like a Ford offset wheel might actually be beneficial as they need a spacer anyway, you might get loads of clearance then.

 

 

As for the thicker discs, might be worth looking at other manufacturers and adapting them to suit, i.e re-drilling to match the PCD and machining the centre bore to suit Peugeot, as long as they have a suitable offset and the bell will fit over a pug hub.

 

 

 

 

All total theory based on what I've seen from other brake kits and arrangements I've seen on pugs over the last few years though, so some may be dead ends!

[benlilly 0]

Here's a rough hub drawing that may also come in handy. It's only very basic but does show the caliper mounting points.

 

As Welshpug mentions, the lower balljoint is a problem is you need to use a disc or disc/bell combination with lots of offset. Even with my 290mm discs, the inner face of the disc could hit the balljoint if the disc offset needed to be greater.

 

205_GTi_HUB___ROUGH.PDF