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Apr 13, 2022 15:20:28 GMT
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Eek! My mate's bought a twin master setup for his NA MX5 that looked similar. I reckoned it was oversized masters relative to the caliper pistons, although not tested it yet. How did he get on with it ? Mine still needs a lot of pedal effort to stop the car quickly, they clearly work though as the brake test roller jumped the car out of if when testing them on that. My setup is this, I'd really like still to try and get a pedal with less effort needed. obp 5:1 pedal 0.625 front master 0.7 rear master All braided or copper lines 4x 38.1mm pistons (x2) Willwood fronts with 282mm discs Ds2500 pads 1x 34mm piston (x2) Corsa C rears with 240mm discs EBC yellow stuff pads Bias valve in the rear line before the T I'm still not sure if I can lock the front wheels, next step could be change to a 0.5 master on the front or even a remote servo, but thats more fitting effort. Still not fitted I'm afraid, but it came off another car with the same brake setup so it should be the same in this car. Not sure about the pedal ratio or pads I'm afraid. 0.7 front master 0.625 rear master 4x 31.75mm fronts with 298mm discs 1x 32mm rears with 276mm discs This setup was apparently a bit hard on the pedal as the pushrod was bent! I've plugged your numbers into my little brake bias calculator spreadsheet and they're coming out pretty good TBH. The spreadsheet's missing some key variables to work out the actual braking torque (things like pad height and friction coefficient of the pads), but the numbers on the far right show a comparison between the different setups for a given weight on the pedal and a given pad friction coefficient. It's skewed a little in that I've applied the rule of thumb that manual brakes take about twice the force on the pedal of servo'd ones. If you'd like less pedal effort than that's fine though! In terms of the numbers, I don't think I have enough of a database of known good braking setups (without bias valves as that futzes things up in the formulas) to know how much braking force is reasonable for a non-servo system. Best I have is Caterhams and my X1/9, both of which have under half the braking power of your setup for a given weight on the pedal. I wouldn't say my X1/9 had particularly stellar brakes though! Interestingly, you're coming out at 85% front bias. I expect you don't need that rear bias valve as that seems fine to me for a FWD, although I haven't driven one with quite as beefy brakes as yours. Might be leaving some braking performance on the table if it's set to cut the rears prematurely. Not sure on the relative pad friction of the fronts/rears though so that might be throwing it off. If you're up for a bit of experimentation you could swap your front and rear masters around. It actually reduces your braking power for a given weight on the pedal, but puts the bias at 78% front. If it feels more competent then perhaps your rears are underutilised. If it starts locking the rears then perhaps 85% is the way to go. Swapping to the 7:1 pedal looks like it'll produce a 29% reduction in pedal effort for a given amount of braking. If that's too much and the pedal feels spongy then swapping to a 7:1 pedal and switching the master cylinders around gives you a 13% reduction in pedal effort, but might need the bias bar re-adjusting if you're locking the rears. |
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Last Edit: Apr 13, 2022 15:27:39 GMT by biturbo228
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Apr 13, 2022 15:32:17 GMT
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The 3-4mm offset on the balance bar sets the brake bias at approx 65% to the front which is the pedal bias you roughly need. If the rears lock up then tweak it a turn for more bias to the front until the fronts lock up first.
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Apr 13, 2022 15:50:33 GMT
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Is 65% what you want on a front wheel drive? The static weight distribution might be pretty close to that already!
Process is good though. Tweak it until the fronts lock first, from wherever it starts at.
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Apr 13, 2022 18:10:47 GMT
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Two different things.
PEDAL bias should be somewhere around 65% ish.
BRAKE bias is determined by caliper & disc size.
Front or rear wheel drive I don't believe makes any difference, inertia will load all the static weight to the front under braking regardless of which wheels propel the car.
i think you will find static weight is far nearer 50/50 than you might think - no manufacturer would deliberately build a front or rear heavy vehicle - it would handle horribly.
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edk83
Part of things
Posts: 862 
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Apr 14, 2022 11:25:50 GMT
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I have roughly 500kg front and 400kg rear, slightly different when I'm sat in the car of course, I sit under the B pillar.
To me it seems like rwd cars have slightly larger rear brakes than fwd as they have more mass on the rear axle to deal with but stopping the car wouldn't be massivly different.
I do actualy have the valve in the rear line pretty much open, if the rears lock I'll close it slightly until they don't.
I've set the balence bar / pushrods to favour the front by 5mm ish and it feels like there is slightly more travel since doing that, needs road testing but noticed a slight improvement.
I'm still not confident that I'll be able to lock the fronts yet, but now it's on the road properly I'll be able to do more testing. I was told before that the pedal ratio is poor, I'm assuming the way to go is just change the pedal for a longer one, could be quite easy but might be an odd driving position as I have my cylinders floor mounted.
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Last Edit: Apr 14, 2022 12:37:45 GMT by edk83
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Apr 14, 2022 12:38:13 GMT
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Yes longer pedal or change the pivot point.
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edk83
Part of things
Posts: 862
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Apr 25, 2022 15:50:57 GMT
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I'd only be able to lengthen the pedal with it being floor mount, that would mean an odd lift your leg up sort of position.  Managed to bag a Funk turbo blanket from a mate, it's for a Ford T3 but made it fit   |
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Last Edit: Apr 25, 2022 15:51:33 GMT by edk83
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Apr 25, 2022 18:42:05 GMT
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If you can weld up the holes for the balance bar and then re drill them a bit nearer the base pivot point it would help.
Either that or extend all of the pedals and fit a floor riser in front of the pedals?
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edk83
Part of things
Posts: 862
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May 20, 2022 11:58:02 GMT
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Mapping on the dyno booked for the 9th June Up at EFI in Warrington so a bit of a trip. I'm going to give it another run out tomorrow on both fuel pumps to make sure no issues there, then change the oil for the posh stuff and larger filter. Now that towing laws have been changed the single axle trailer I built for it has been sold, why have a single axle when you can have two? Shame the new one is too wide for the side of the house but at least now I can hitch and go from the garage.  |
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Last Edit: May 20, 2022 11:59:35 GMT by edk83
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edk83
Part of things
Posts: 862
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May 23, 2022 10:59:14 GMT
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A bit more road testing and oil now changed for the posh stuff, seems to run quite well although all the warmup enrichment etc needs doing as its lean and misfiry for the first min or so, even on hot starts, should all get sorted on the dyno. Did a bit of a 5th gear mini pull, made 4psi and it feels strong even though I'm still way off where the power is going to come in! Also managed to get the best mileage reading ever     |
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edk83
Part of things
Posts: 862
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Well the Dyno happened, drove it the 2 hours each way to Efiparts in Warrington. Did all the midrange response stuff and idle, first power run on wastegate made 255hp at 8psi We were almost ready to start going for power and the oil feed to the turbo decided to feed the dyno instead  Oil pressure stayed up so all ok but clean up time plus taking the oil filter, sandwich plate all off to access the fitting ended play. So it's now all of in bits and I'm redoing the oil cooler and turbo feed, found in the end that the alternator flexing under high power rubbed the an4 fitting and undid it! Grinder will be adjusting the alternator some more. Video link below! |
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Last Edit: Jun 13, 2022 12:49:22 GMT by edk83
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edk83
Part of things
Posts: 862
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Jun 13, 2022 13:01:11 GMT
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While compact, the oil cooler and turbo feed, sensor is a royal pain to get to. Offending AN fitting hidden behind that lot.  Yeah... that sucks, redesign incoming soon. either the feed line is enough to pull on it and undo it or the alternator caught it. Unable to take the an fitting off with the alternator there its that close, so housing off instead.  Adjusted, yes I covered the oil outlet.  Turbo feed will go straight to that now I've decided, getting rid of the horizontal load on the fitting. Changing the oil cooler lines to branded ptfe and AN, the oil P sensor can come off the return of that, as thats the pressure actually going into the engine. |
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Last Edit: Jun 13, 2022 14:16:08 GMT by edk83
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Brigsy
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Posts: 617
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Nightmare at least oil pressure stayed ok so hopefully no damage done. Never find out issues like that until proper load and vibration make them happen under full throttle.
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edk83
Part of things
Posts: 862
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Exactly that, I was being told I should fully test everything before the dyno, but then I was on an untested map and hadn't revved it over 5k or made more than 4psi. So far so good then really, at least now it's safe to put some road miles on and then we'll be back for another go, even starts from cold nicely now too. New fuel pump just arrived, I'm currently running a china 044 copy, which to be fair has run well for the last 4 years and made 212hp Na, made 255hp this time as well with no issues. But if I find its limit is under 300hp I'll be disappointed. I did add a second one with the idea that I could just run 2 pumps, while this would work it overloads the reg and more fuel pressure means hotter fuel. The second china pump works but is very noisy so thats coming back out for the bin, new genuine AEM pump is replacing it, plan is to then run that as the primary and keep the old decent 044 copy plumbed in as spare / failover.  |
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Last Edit: Jun 14, 2022 9:34:58 GMT by edk83
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Brigsy
Part of things
Posts: 617
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Jun 14, 2022 10:30:23 GMT
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All you can really do on an unmapped car is just test the static stuff and low load to confirm if its drivable, its always a fingers crossed that it will work ok. Ive just had a bizarre fuel line resonance issue causing a lean spike at 6k rpm when Chris@Efi was mapping a car for me, could not forecast it beforehand and Chris could not map it out so had no choice but to stop tuning further until rectified.
Good poeer for 8lbs boost though, itll be flying once its been full mapped. Ive been looking at the aem 400 to replace my aging bosch 044, let us know how it goes, i believe its direct replacement.
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Last Edit: Jun 14, 2022 10:31:21 GMT by Brigsy
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edk83
Part of things
Posts: 862
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Well it's in there, not tested yet. New oil cooler fitted, just need to put the braided lines together and figure out a few fittings.  |
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Brigsy
Part of things
Posts: 617
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Regarding oil cooler, whats the main use for this just road use, or potential track use?
Ive logged oil temp with a decent gauge on 3 of my cars and road use they never get hot enough to need a cooler for road use, and all are quite highly modified turbo setups. Usually see a max of 90-100deg when doing a few full throttle pulls, which is no problem on a modern synthetic oil.
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edk83
Part of things
Posts: 862
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Jun 20, 2022 15:31:41 GMT
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Yeah I want to be able to do 10 laps of Blyton without having to worry. New an8 cooler mounted  Just waiting on a few more fittings and I can make the lines, a bit lower than before but at least all the fittings will be easy to access and check.  |
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Jun 21, 2022 12:18:47 GMT
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i reckon the amount of cars that turn up to a dyno, drive straight on and start mapping, are basically zero.
when i had mine done i had a hardon about small niggles like that and they still found an issue (every time the throttle closed it returned to a different voltage) you just cant predict some things nor create the same conditions.
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Last Edit: Jun 21, 2022 12:19:47 GMT by darrenh
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