Rear uprated ("race") brake upgrade finally done

[KnifeySpoony]

So after pondering this for a couple years, then my hand being forced by the abysmal quality of the stock Sierra calipers and shockingly short pad life in the rear, I finally upgraded the Caterham uprated brake kit. The hard part of this is installing the (supposedly mandatory) bias valve. Most of my trepidation was due to my complete ignorance and fear of brake line fittings/flares etc. Thankfully DPR Motorsports in the UK agreed to sell me their flexible line kit with all premade lines to simplify the install. Still need to bleed and leak check but it's all in. Pics below. Will give updates on braking performance and pad life as I go.

 

Edited March 3, 2025 by KnifeySpoony

[slowdude]

Slick install. Looking forward to how you enjoy it.

[KnifeySpoony]

I can confirm, the valve is indeed necessary. It easily locks the rears in 4 of the 7 more "open" positions on the valve. Ended up on position 3, but that was just on the street. With different tire/brake temps and after they're fully bedded, that may change.

[KnifeySpoony]

First day on track yesterday (Sonoma) with the new setup. Was cold in AM, hard to get temp in tires so took 2 sessions to get them fully bedded. As they bedded, pedal feel improved more - it is much firmer now. Upon initial install I was slightly disappointed, thinking that it would be much firmer than prior. Now it actually is. With the pedal travelling less, heal and toe is much easier. 

 

Overall the brakes have way more power now, better pedal feel, much more confidence. The car was definitely overbraked at front in standard form (4 pot uprated brakes in front, sierra sliders in rear). Huge upgrade in braking performance - I could brake so much later and harder. Easy to dial in balance with the lever. If you're ok with giving up the handbrake, I highly recommend it. And that's just on the performance alone, which was not at all my reason for doing it- that was durability. Will report back on that after further outings. 

[KnifeySpoony]

Oh and just to clarify - when I say the car brakes harder, I don't just mean it brakes harder for a given pedal pressure. I mean that previously the fronts were locking so early, I couldn't slow the car well. Now the car is using all available traction front AND rear to slow the car.

[SK400]

KnifeySpoony

I’m installing the updated rear brake calipers as we speak.  I had read and heard from Roger at Meteor not to install a bias valve because it destroyed the brake feel and rather adjust the bias and rear locking risk using different rear pads with lower friction than the RS pagid pads that come with the kit.   What are your thoughts? 
 

also would you mind showing how you connected the biais valve to your master cylinder?  
 

thank you 

 

[KnifeySpoony]

Does the bias valve negatively affect pedal feel in some way? I suppose it's possible but it's still dramatically improved over stock. The pedal is much firmer and with much less dead zone. It's a huge upgrade in feel alone.

 

I suppose it's possible to find a lower friction pad that could balance with the front, but the increase in braking power with the new hardware is dramatic, so you would need to make sure you're running a very high friction pad up front. And if you run a low friction pad in rear, it may not be able to cope with the heat. Even with the larger/vented rotors, the rear brakes still run quite a bit hotter than the fronts. 

 

Re: connection - the connectors look the same as they do going into the bias valve in my photo.

[Croc]

@KnifeySpoony  I never understood your issues with rear bias causing rear pad wear. It had never been my experience after decades with Caterhams on track. I have always followed the accepted wisdom described by @SK400 of you run differential pads front and rear.  A correctly working Caterham brake system should give you years (or decades in my case) on pads both front and rear.  But I did believe you were seeing a real problem on your car and now you are not alone.

 

Recently a 2021 Caterham landed in my garage needing attention.  The former owner would use rear pads up in 6 days at Mid-Ohio - very similar complaint to you.  His solution was a Wilwood brake bias valve installed off the Caterham race master cylinder - adjustment knob under the dash.  Front brakes are the upgraded 4 pots and rears are standard Sierra.

 

 

 

It does work in this set up albeit lacking feel but running two proportioning valves just feels really wrong - the Caterham race MC does have a screw adjustable proportioning valve - at least the one in the photo does

 

So I am now going through the logical decision tree for what might be going on.  

 

1) Crimp from manufacturing or build in front brake lines - Visual inspection reveals nothing but I plan to blow out and pressure test the brake lines to check.  Quite possible as I have seen damaged brake lines new from factory before

 

2) Handbrake is dragging with rear brake on even though lever shows disengaged - no not here

 

3) Brakes lines plumbed into MC incorrectly i.e. swapped - no not here.

 

4) Calipers blocked brake fluid galley or piston actuation faulty - no it tests out fine on all 4 wheels

 

5) Race master cylinder assembled backwards - This is my betting winner - waiting on a new one from Josh to swap in and check.

 

 

 

  

[KnifeySpoony]

While certainly some people get long life from the standard rear brakes, there are many people that have the same issues I've had. Comes down to the usual variables, of course (pace, power, circuit, weather, etc). But also, caliper quality may have declined over the years. There was a thread on blatchat I took part in debating this issue. Various posters telling me I'm doing something wrong lol. Tell me they are fast, but their rear brakes last forever. Then post videos to prove it showing tracks that have no real hard braking zones. 

 

Check out this quote from the DPR Motorsports website regarding the uprate rear brake upgrade: "This upgrade provides far better rear brake pad longevity, much improved brake pedal compliance and a more robust and leak free system as found with the standard rear Caterham calipers.  If you are tired of going through so many rear standard pads and discs after only a few track days this is a ‘must have’ upgrade!"

 

This exactly describes my problems - pads that disintegrate after a few days on track, and failing caliper seals. I clearly was not the only one... The firm pedal and greatly improved braking performance by optimizing bias are the icing on the cake really.

[KnifeySpoony]

Re: the 2021 car you're looking at. I'm not sure I understand why putting a bias valve on the stock setup makes any sense. Sure, you could reduce the contribution of the rear brakes and make them last longer, but at the expense of massive performance loss. The car with that setup is already overbraked at the front. Making it worse doesn't make any sense to me. The solution is to upgrade the rear hardware. The problem was solved by Caterham years ago when they developed the race rear setup.

[S1Steve]

42 minutes ago, KnifeySpoony said:

Re: the 2021 car you're looking at. I'm not sure I understand why putting a bias valve on the stock setup makes any sense. Sure, you could reduce the contribution of the rear brakes and make them last longer, but at the expense of massive performance loss. The car with that setup is already overbraked at the front. Making it worse doesn't make any sense to me. The solution is to upgrade the rear hardware. The problem was solved by Caterham years ago when they developed the race rear setup.

Croc and I discussed this few weeks ago. I couldn’t get my head around it then and still don’t. Now that Mike is getting into it, we’ll find out the final solution. My thoughts to Mike were why.. WTF, they did what..🤔🤔🤣🤣

[11Budlite]

I just thought I would add one more data point to this discussion. I've done a little over 15 trackdays with my 2019 310S with the standard brakes and standard M/C over the last 4 years. I'm still on the original brake pads and have only done a yearly brake bleed for maintenance. The only time I use the parking brake is when it's on the trailer and I haven't noticed any unusual drag on the rear brakes. I'll admit that I was real easy on the brakes for the first couple of years, and only in the last couple have I started braking harder and deeper into corners.

I just measured my brake pads and the fronts have between 7-8mm of pad remaining and the rears have around 2mm of pad left. YMMV, but I'm definitely getting more wear on the rear brakes with my setup.

[BruceBe]

That’s a bunch of brake hose in that install. Is the entire rear circuit now hose? 
 

Brake component wear is very much a function of the circuits you drive, and more importantly, the driver’s approach to the braking event. This kit allows you to decelerate faster, earlier in the brake event, rather than waiting for the weight transfer to the front of the car in the “pedal squeezing” phase. And because the rear is doing more work early in the brake event, before the front is doing much, overall braking distances are shorter. To maximize the benefit of this kit, you’ll need to change the way you brake a bit, becoming a bit more aggressive early in the brake event, and remembering to modulate out a little as the weight transfer takes place. 

 

Cheers,

-Bruce

[KnifeySpoony]

Yes the rear circuit is all hose. I had my concerns about about pedal feel/etc, but was reassured it would be fine. I guess this setup is popular with 7 racers in the UK/europe. I'm sure having more solid line would improve pedal feel even further but even with this setup the improvement over stock is dramatic. Certainly the caliper improvement more than makes up for any downside to the soft lines.