KnifeySpoony Posted November 5, 2022 Share Posted November 5, 2022 My car is mostly a track car, I really only drive it to/from the track. I had considered this upgrade for maximum performance during my 420R build last year, but decided to see how the stock setup was. I found it a little over-braked in the front, but upgrading the rear pads to DS3000 has pushed the bias rearward enough that I am happy with the braking performance. However given my recent issues with interference between my rear calipers and watts linkage arms (https://www.caterhamlotus7.club/forum/techtalk/rear-brake-caliper-contacting-radius-armwatts-link), I am thinking about this upgrade yet again. Presumably the lower profile rear calipers won't have any interference issues. I'm OK with the handbrake delete (I'm in the US and in my state the car will never be inspected again). This setup seems to need a proportioning valve, although my calculations of brake bias don't seem to suggest the bias moves all that far rearward compared to the standard setup. I'm wondering if anyone has done this upgrade, or driven one of the R300/420R race cars with this setup and can comment on performance. I have never plumbed brake lines, and I would have to get the appropriated line flaring tools etc, but it seems not too difficult to learn. Also I would need to decide on a cockpit-mounted prop valve vs one in the engine bay (much easier to install). Wondering if the easy adjustability is really necessary, as I won't racing in the race. Link to comment Share on other sites More sharing options...
KnifeySpoony Posted November 19, 2022 Author Share Posted November 19, 2022 Really, nobody? Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted November 19, 2022 Member Share Posted November 19, 2022 I can't find anything in the archives. Are they referred to by another name?Jonathan Link to comment Share on other sites More sharing options...
KnifeySpoony Posted November 20, 2022 Author Share Posted November 20, 2022 I guess CC refers to them as "uprated" brakes. https://caterhamparts.co.uk/calipers-pads-discs/2976-rear-brake-upgrade-kit-race-only-no-handbrake.html?search_query=brake+pad&results=251 Link to comment Share on other sites More sharing options...
21jigsaw Posted November 21, 2022 Share Posted November 21, 2022 I have the earlier version of solid discs and ap racing calipers and a spot handbrake caliper(mot compliant once a year!!!). The earlier version was developed on Vauxhall race cars running slicks they then changed to vented discs (front vented disc on the rear) for a performance improvement( wear or retardation??). I run it on my 21 which is 695 kgs which is enclosed due to the bodywork and runs around 400deg c . I intend to upgrade to vented discs due to high pad wear on the existing setup. If you change you will need new uprated hubs, ears, caliper spacers, calipers, disc spacer, specific rear discs ( as front but bigger internal dia) and if you wish to run on the road a mechanical handbrake caliper / mounting. The rear track will increase by approx 25mm. Hope this helps. Dave Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted November 21, 2022 Member Share Posted November 21, 2022 Thanks: searching the archives for uprated + rear + brake gives;https://duckduckgo.com/?q=site:caterhamlotus7.club+uprated+rear+brakeJonathan Link to comment Share on other sites More sharing options...
KnifeySpoony Posted November 24, 2022 Author Share Posted November 24, 2022 Hmm interesting that it increases the rear track by so much. I wonder if that would affect handling balance enough to require change in other setup. Link to comment Share on other sites More sharing options...
Area Representative Geoff Brown Posted November 25, 2022 Area Representative Share Posted November 25, 2022 I do believe that upgrading to the rear race calipers requires an upgraded hub as well........REAR HUB UPRATED BRAKES ONLY - Caterham Parts Link to comment Share on other sites More sharing options...
aerobod - near CYYC Posted November 25, 2022 Share Posted November 25, 2022 Looks like the kit from Caterham includes the upgraded hubs, together with the adapters to modify the race ear caliper mounting points: https://caterhamparts.co.uk/calipers-pads-discs/2976-rear-brake-upgrade-kit-race-only-no-handbrake.html?search_query=brake+pad&results=251 Link to comment Share on other sites More sharing options...
mic Posted November 25, 2022 Share Posted November 25, 2022 You will have to fit new ears also. The mounting for the caliper plate is totally different. Link to comment Share on other sites More sharing options...
KnifeySpoony Posted November 25, 2022 Author Share Posted November 25, 2022 Yes, the whole assembly lateral to the DeDion tube changes with this setup. I just didn't realize that the track changed so much. I already get some tire rubbing on my rear wings, so I'm not sure how things will all fit if that track width change is indeed a thing. Link to comment Share on other sites More sharing options...
21jigsaw Posted November 25, 2022 Share Posted November 25, 2022 , I also run 2,5 deg negative camber on the rear.Dave Link to comment Share on other sites More sharing options...
7 wonders of the world Posted November 25, 2022 Share Posted November 25, 2022 Whats the piston diameter on the AP race rear calipers please ? Link to comment Share on other sites More sharing options...
KnifeySpoony Posted November 26, 2022 Author Share Posted November 26, 2022 10" vented discs. Which is the same as the factory option for uprated front 4 pot brakes. But it uses a 2 piston (fixed) caliper. Link to comment Share on other sites More sharing options...
7 wonders of the world Posted November 26, 2022 Share Posted November 26, 2022 I'm looking for the piston diameter in the caliper please Link to comment Share on other sites More sharing options...
KnifeySpoony Posted November 26, 2022 Author Share Posted November 26, 2022 The caliper is a CP5119 with 44.5mm pistons (unless the Caterham piston spec is something different somehow). The standard Sierra rear is a 42.8mm piston, so minimal increase in size. The rotor does go from 232mm to 254mm, so there is some additional torque there. I'm kinda surprised it needs a prop valve tbh. https://caterhamparts.co.uk/15252-thickbox_default/brake-caliper-rear-race-10-lh.jpg https://apracing.com/race-car/brake-calipers/formula-car-range/2-piston-fia-f4-cp5119 Link to comment Share on other sites More sharing options...
Leadership Team SLR No.77 Posted November 26, 2022 Leadership Team Share Posted November 26, 2022 Is all this work purely to achieve more clearance between the caliper and the Watts link assembly? Link to comment Share on other sites More sharing options...
KnifeySpoony Posted November 26, 2022 Author Share Posted November 26, 2022 My initial interest (pre-build even) was to improve braking performance. Then, after upgrading rear pads I was content. Now that I'm having the clearance issue, I'm considering the upgrade again, as apparently that would eliminate the issue as well. Link to comment Share on other sites More sharing options...
alan c Posted November 26, 2022 Share Posted November 26, 2022 Sorry for slight thread high jack but question for jigsaw - what are you using as the handbrake caliper?i have the old AP set up and the handbrake caliper is useless so a good replacement would be nice. Link to comment Share on other sites More sharing options...
21jigsaw Posted November 26, 2022 Share Posted November 26, 2022 Its a Hi Spec spot caliper . Not very effective. I looked into this a few years ,you need a lever ratio of approx 15/1 for a good mechanical handbrake this system along with a modified hand brake lever was about 9/1. To get a higher lever ratio the caliper installation required redesign. This problem has been visited before E Type Jag ,Lotus Elan these types of design would provide adequate leverage put packaging might be the issue. Willwood might be worth a look. Dave Link to comment Share on other sites More sharing options...
Area Representative Geoff Brown Posted November 27, 2022 Area Representative Share Posted November 27, 2022 'However given my recent issues with interference between my rear calipers and watts linkage arms' - Getting back to the original issue I cannot understand how this is occurring ?Or am I missing something obvious.Seems to be an expensive & time consuming way of trying to get over a simple problem.I know that inboard movement of the caliper during pad wear creates a decreasing clearance but not to the extreme.The clearances on my R400 are fine as is the rear anti roll bar connection to the de Dion ear. Later cars have a different connection setup of the AR to the ear which if the adjustment is not correct causes interference with the inside of the rear wheel.The only time that the Watts Linkage & calipers would cause an obstruction is if they have both been assembled incorrectly. Are the caliper spacers correctly fitted? Are the linkages assembled correctly though this is almost impossible not to do correctly? Link to comment Share on other sites More sharing options...
KnifeySpoony Posted November 27, 2022 Author Share Posted November 27, 2022 The problem arose after changing my DeDion ears from 1.5 to 2.0 deg. This apparently brought the calipers in closer to the linkage. Before the upgrade there was no contact. I'm not sure how/why Caterham sells the 2.0deg plates if they cause this issue, but I guess Caterham gonna Caterham. related thread: https://www.caterhamlotus7.club/forum/techtalk/rear-brake-caliper-contacting-radius-armwatts-link Link to comment Share on other sites More sharing options...
Area Representative Geoff Brown Posted November 30, 2022 Area Representative Share Posted November 30, 2022 If CC endorse the 2.0 degree ears by having them on sale then they either are not aware of the problem, ignore it or have an 'easy fix'.Of course the cheapest & easiest course of action is to revert to 1.5 degree ears........ Link to comment Share on other sites More sharing options...
Leadership Team SLR No.77 Posted November 30, 2022 Leadership Team Share Posted November 30, 2022 Re #22 Are you aware as to whether there's a contact issue with the 2 degree ears if using standard radius arms rather than a Watts link setup? A swap to radius arms might be the easiest solution to your problem and you definitely wouldn't be the first to go that route, myself included.Stu. Link to comment Share on other sites More sharing options...
rgrigsby Posted November 30, 2022 Share Posted November 30, 2022 I ran this setup years ago for a while, combined with the AP uprated front calipers. It was the best brake setup I've ever had on the car but the handbrake caliper is hopeless and just kept eating itself. I gave up in the end and moved to a 2 pot Hi-spec rear caliper, it's effective in terms of ultimate braking performance but the pedal feel has never been as a good as the AP setup. Link to comment Share on other sites More sharing options...
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