E30 with SR20DET

[keri-WMS]

Soon to be fitted to a track car near me....!!!!







It's so top secret it's not even got a WMS logo yet (pre-production caliper)! 290x19mm vented rear which retains the E30 handbrake, and a 2-pot CNC WMS caliper - all fits inside the 15" BBS.

[Theo]

Looks great! What's the 290mm disc from? I thought it was going to be a 294mm jobby from an e46 325i?

[GeoffBob]

Very nice indeed Keri

[keri-WMS]

Looks great! What's the 290mm disc from? I thought it was going to be a 294mm jobby from an e46 325i?

It's the same disc, turned down to 290mm so it will match the biggest disc I can get in a BBS at the front....

Very nice indeed Keri

Thanks!

[Theo]

They're on

They fit perfectly, kudos to Keri! Thanks a lot for all your hard work you put into developing the kit, I'm hugely impressed. I really do admire the attention to detail you put into your kits - for anyone reading this who's interested in some uprated brakes, I would strongly recommend having a chat with Keri.

Initial impressions are very positive, shame that the roads are so slippery at the moment as it's preventing me from really getting some heat into them. Pedal feel is superb, whether this is down to the new caliper, new pad compound or new master cylinder diameter I don't know. Probably a combination of the above.

Thanks also to Geoff for running the calculations and prescribing a .75" master cylinder. I'm really happy with the brake pedal now, by far the best it's ever been.

[keri-WMS]

Sweeeeet!

Ta for the feedback, glad you like them. Looks like the brake line etc is clear of the shock ok?

[Theo]

Yeah, plenty of clearance to the shock. No fitment problems whatsoever.

[winx]

as per my pm to Keri on Friday - very interested

[GeoffBob]

They're on

They fit perfectly, kudos to Keri! Thanks a lot for all your hard work you put into developing the kit, I'm hugely impressed. I really do admire the attention to detail you put into your kits - for anyone reading this who's interested in some uprated brakes, I would strongly recommend having a chat with Keri.

Initial impressions are very positive, shame that the roads are so slippery at the moment as it's preventing me from really getting some heat into them. Pedal feel is superb, whether this is down to the new caliper, new pad compound or new master cylinder diameter I don't know. Probably a combination of the above.

Thanks also to Geoff for running the calculations and prescribing a .75" master cylinder. I'm really happy with the brake pedal now, by far the best it's ever been.

Stunning work Theo. Congrats to both yourself and Keri.

Also pleased to hear that the 3/4" M/C gets the job done. Do keep in mind that (compared to your prior setup) you will need to set your prop-valve to a lower value. Around position-2 if I remember correctly from stuff I posted up earlier. But then I am sure you will verify the exact position for yourself during dry/warm weather. Pity you can't pop down here - Hot as 'ell at the moment. Actually too warm TBH. No where near enough rain for the time of year.

Better get ready to sell lots more keri!

[Theo]

Thanks Geoff. All credit needs to go to Keri, I just bolted the bits on to my car!

Regarding bias, I need to spend some time in the car getting it to a good setting. I need to centralise the bias bar and then take it from there. I've finally swapped the lever style proportioning valve in favour of a screw type which gives me the same maximum reduction in pressure (57%) but allows for much finer adjustments.

I calculated the rear brake line pressure as being 544.6psi with 35kg (77 lbs) or pedal force with a ratio of 6.25:1. How exactly do I achieve the desired knee pressure of 300psi? To be honest, I'm not even sure what is meant by 'knee pressure' could you explain it to me please? (apologies if you have already done so in the past!)

Don't get me started on the weather. I HATE cold weather, it's pissing down with snow and meant to drop to -10 on friday night. If Silverstone does go ahead the daytime maximum temperature is forecast to be -1

[keri-WMS]

as per my pm to Keri on Friday - very interested

Cheers Henry, sorry for not replying! I'll let you know as and when we manage to get them in production....

Stunning work Theo. Congrats to both yourself and Keri.
.............
Better get ready to sell lots more keri!

Thanks Geoff! Re more, it would be nice but it'll need a large batch of the calipers to be made with custom small (E30 spec) pistons - I'll need to do some juggling to make that happen so it'll be a while.

Don't get me started on the weather. I HATE cold weather, it's pissing down with snow and meant to drop to -10 on friday night. If Silverstone does go ahead the daytime maximum temperature is forecast to be -1

You'll be fiiiiiiine.......(just make sure you post up some in-car footage!!! )

Have you got a spare set of BBS's with normal road tyres? Loads of small cuts are what you'll need if there's any ice about....assuming they open the track?

[Theo]

I have no road tyres! several r888s, a pair of Avon ZZRs (which are more or less identical to the r888) and a pair of Michelin pilot sport cups.

I drove the car with r888s yesterday and it was ok with a gentle foot.

[GeoffBob]

Regarding bias, I need to spend some time in the car getting it to a good setting. I need to centralise the bias bar and then take it from there. I've finally swapped the lever style proportioning valve in favour of a screw type which gives me the same maximum reduction in pressure (57%) but allows for much finer adjustments.

I calculated the rear brake line pressure as being 544.6psi with 35kg (77 lbs) or pedal force with a ratio of 6.25:1. How exactly do I achieve the desired knee pressure of 300psi? To be honest, I'm not even sure what is meant by 'knee pressure' could you explain it to me please? (apologies if you have already done so in the past!)

Theo, what you need to understand is that a proportioning valve doesn’t cap (regulate) your rear line pressure to some static (fixed) value. What is does is limit the rate of increase in rear pressure, typically by a factor of around 3 (66%). You state a value of 57% (I assume you got this from your data sheet for your new valve?) which means that your valve specifically reduces your M/C pressure to the rear calipers (after the knee pressure has been reached) by a factor of 2.3.

The knee pressure is defined by adjusting the prop-valve (mine is also a knob type BTW). At any pressure (from the rear M/C) below the knee pressure, the pressure at the outlet of the prop valve will be the same as that at its inlet. In other words, the prop valve functions as an open valve (no restriction). However, when the inlet pressure reaches the knee pressure (defined by adjusting the knob) any further increase in pressure (above and beyond the knee pressure) will be reduced by a factor of 2.3.

Consider the graph below for some arbitrary valve (a Willwood I think?) where the pressure (after the knee pressure) is reduced by a factor of 3.0.



Lets say the knee pressure is set to 30bar (for arguments sake). As you press the pedal the pressure at the inlet and outlet of the prop valve will rise in unison. However, above the knee pressure (30bar), the prop-valve outlet (caliper) pressure will rise at a rate of roughly 33bar per 100bar of inlet pressure (from the M/C). Thus, to achieve a caliper pressure of say 40bar (10bar more than the knee pressure) you will need to raise the prop-valve inlet (M/C outlet) pressure to 30bar + (3*10bar)=60bar.

In your specific case, however, you will need to raise the inlet pressure to 30bar + (2.3*10bar)=53bar to get 40bar at the outlet of the prop valve. The difference between the inlet and outlet pressure is taken up by the effort required to displace the sprung loaded plunger inside the device. By turning the knob you simply adjust the tension on the spring.

HTH
Geoff

[GeoffBob]

BTW, your test procedure will be as follows (assuming your brakes are warmed up)

1) Set your bias bar to 50%.

2) Wind the prop-valve all the way out, raising the knee-pressure as high as possible.

3) Undertake several straight-line threshold braking manoeuvres and verify for yourself that your rears lock-up (as the cars weight shifts forwards) well ahead of the rears. Do each at around 40 to 50 mph. Don’t be shy to press the pedal.

4) Start winding the prop-valve in until the front brakes lock up ahead of the rears. At this point you have wound the valve too far and you need to wind it back in a tad. The objective is to get the front and rears to lock up simultaneously.

[Theo]

Thanks for the explanation about proportioning valves and knee pressures, I think I understand now.

Your recommended proceedure for setting up the brake balance is what I had intended to - I'll have to remind myself how many turns there are from one extreme of adjustment on the balance bar to the other so I can set it at exactly 50/50. I had far too much front bias yesterday, but then again I've bedded the front pads in, but not the rears.

[GeoffBob]

Theo, in your specific case, if you dont adjust your prop valve knee pressure down to around the 300psi mark you'll find that you'll need to substantially adjust your pedal bias forwards to prevent your rear wheels from locking up. I suspect that this is the direction that you were heading in. Given that your rear discs and calipers are of comparable size to the fronts, it will take very little pressure to get your rear wheels to lock up as the cars weight shifts over the front wheels while braking, so you need to get that knee pressure down fairly low, as I showed in one of the earlier calculations I did for you. If you do go the route of setting your prop valve higher, but with more forward pedal bias you will find yourself in the situation where your rear traction fraction will lag behind the front at low pedal forces, and then rapidly catch up as you push the pedal harder. This is not the situation you want. You ideally want those two curves (front and rear) dead bang on top of each at any pedal force.

Also, keep in mind the difference between how your prop valve and your pedal bias work. Whatever pedal bias you set, that bias is fixed regardless of how hard you push the pedal. The prop valve, on the other hand is a dynamic device, meaning that the way it affects your bias is a function of how hard you push the pedal. It needs to work this way in order to ensure that the rearward bias diminishes as your cars weight shifts forwards. Don't let anyone ever tell you that a bias bar and prop-valve do the same thing. They are similar, but also very different.

Also, don't forget to remind yourself not to forget which direction you need to turn the prop valve to either increase or decrease the knee pressure. Else you'll be out there fiddling blindly. Have fun in the snow

[Theo]

Thanks for the further info, I'll be sure to carefully dial in the braking balance with the correct procedure.

I've chickened out of Silverstone this Friday, I'm sorry to report. As soon as is possible, I'll be making a late booking on another track day where I can be sure of some decent weather.

[keri-WMS]

Bummer! Are they giving you a refund or anything?

[Theo]

They're giving me a full credit against another trackday, so I'm booking the the same track for Feb 5th. Hopefully the snow will have fecked off by then.

[Theo]

I was meant to be doing a track day at Brands Hatch tomorrow but it's been cancelled. Really annoying as I am desperate to try out the new brakes on track.

I'd also spent a while fitting a spare VDO temperature gauge for the differential and wiring everything up. Plan is to see what peak temperature I get with a standard backplate versus a Z3M backplate which has the additional cooling fins. What sort of temperature range is ok? I'm using Castrol B373, which is apparently what was originally used in these diffs before SAF-XJ. Incidentally, on the bottle it says 'for competition use only, not for normal road use' - why is this?

Come to think of it, if it transpires that the diff is not overheating with the standard backplate, there's little point in faffing about fitting the Z3M plate. Instead I would think more seriously about fitting an E36 backplate with twin hangers. The following photos show the three backplates as a comparison, and secondly someone with an e36 backplate fitted.

[gareth]

There's one at brands hatch on the 22nd december for £119... but that's still a fair way off.

If you decide to fit a E36 backplate, don't mess about spacing it off, just whip the spool out of the diff, knock the trigger wheel off and fit a E36 one. They're a straight swap. I may have on kicking about here if you need one (trigger wheel, not backplate). The E36 plate is flatter and has a suitable reduced trigger wheel diameter

[Theo]

I think I've given up on the idea of a December track day. Had Silverstone booked for the 3rd - cancelled. So I used the credit to book a day at the same track on the 5th February.

With Brands Hatch being cancelled I now have a credit for 'Focused Events' so I'm limited to booking one of their future events. I quite like the look of the new Snetterton layout, which makes it the 2nd longest circuit in the UK.



Re. the trigger wheel - that would be great if you do have a spare.

[GeoffBob]

I have the E36 backplate on mine Theo. I had to do it after I bent the single mount.

I have a water-jet cutter at my disposal, so making up a spacer was an easier option for me rather than removing the spool to swap the trigger wheels for the speedometer (I didn't even remove the diff from the car). If you would prefer to cut a spacer rather than remove the spool, then I have posted the DXF file on the zone before. Otherwise, exactly as per Gareth's instructions.



I'd be very interested to hear what sort of temperatures you record.

I'm totally guessing, but Castrol B373 may contain chlorinated paraffin which can bring about corrosion issues (iirc), and would thus not be recommended for daily-drivers.

[gareth]

3 miles at snetterton, now that's a fair old length!

I was planning on doing the next trackaction one at brands hatch but it misses my girlie's return from Canada by two days and i want to really scare the hell out of her so will wait for a later one.
Who's the silverstone one booked though?

[Theo]

Geoff, it was your car which got me thinking about the e36 back plate a while back. I've downloaded the DXF file already, should I choose to go that route. Thanks for making that available.

I went for a 10-15 mile drive this morning which was frustratingly slow thanks to traffic. Despite never exceeding 80mph and generally plodding along at 50mph the Diff got up to 70 degrees. I'm suprised it even registered on the gauge.

Gareth - Silverstone is booked through Easy Track if you fancy it. Bit of a trek but always nice to drive on an F1 circuit. Trick is to do a huge wheel spin/donut/skid and see if the black marks are still there on Grand Prix weekend.

[GeoffBob]

[Theo]

I also take one of those infrared heat guns to the track to check tyre temps, but it only goes up to 200 degrees C. I want to measure the temp of my passenger bulkhead as has gone a bit brown and tends to melt peoples shoes. I think some heat reflective material is in order.

I think this is the ideal backplate - twin hangers, increased oil capacity, provision for M10x1 temp sensor and cooling fins.

I wish I had the chance to do things like that! God only knows why I live down here in a 3rd world sh!t-hole. I keep promising to come home one day. Snow wasn't that much of an inconvenience, surely?

The snow isn't too bad. It's the 11.5 months of other shit weather which pisses me off!

[e30topless]

I want to measure the temp of my passenger bulkhead as has gone a bit brown and tends to melt peoples shoes. I think some heat reflective material is in order.

I need one of these in my car, my good lady is always complaining her toes are cold !

[gareth]

Gareth - Silverstone is booked through Easy Track if you fancy it. Bit of a trek but always nice to drive on an F1 circuit. Trick is to do a huge wheel spin/donut/skid and see if the black marks are still there on Grand Prix weekend.

Haha, I hadn't thought of that!

I have one of these:
http://uk.rs-online.com/web/search/sear ... vc=prev_uk
ideal to find out how hot standard size brakes with EBC reds can get a on a M30 touring (a minute or two after pulling intothe paddock...)

Yes, that is in °C!

[Theo]

That's good value, does it come with the probe shown on the website?

[gareth]

Nope, it's just a pointy-gun type affair. I believe the probe can be used on the next model up. Sadly it has now been discontinued It was a proper bargain too

[GeoffBob]

This is what I use.



Available here

Good for up too 800'C.

[gareth]

Nice
Google reckons that converts to around £110. A lot more than the £30 mine cost. Sadly I've not seen any others close to the price of mine while keeping a decent maximum temperature range

Oh well, at least i have one

[keri-WMS]

Oh look, the WMS T30x has landed!

Safe to say this is a "low flex" caliper with a bolted in mono-bridge, now to get it on a 290mm disc and inside a 15" BBS on a car for some testing...anyone round here with 290mm rear brakes game?

[Theo]

Nice!

I may be able to help with the testing side of things