Ben280

Cool! For some reason I thought you got a 550. Should make it easy for troubleshooting!

@DuffyMahoneyHow are your injectors wired into the ECU? If i'm not mistaken there are only 4 injector drivers on the haltech board. Are you running 2 batches of 3 injectors? I seem to remember from a few pages back you got a CAS dizzy piece so you'd have a cam signal heading to the ECU for a more sequential system.

Haltech's are a bit different than the MS3 I use, but the injector timing sounds to be fairly out of joint from Duffy's video. If the crank sensor is bad, inconsistent or just something the computer can't figure out, the MS would either not start, or show errors in the Sync gauge. I doubt the Haltech would try an muddle through a bad cranking trigger. I the trigger and home wires are also shielded bundles in the Haltech wiring harness, so unless Duffy isn't using those, noise shouldn't be an issue either. Injectors are behaving badly at a minimum, I'm interested to hear what the report on them is!

It sounds to me like Madkaw has a prop valve installed in the rear circuit, and has it dialed all the way down. You can only "bias" a dual master cylinder system, otherwise you are proportioning the amount of force to the rear. This would be mostly in line with what OP had to do. Would be helpful to know the model Wilwoods you are using, as saying you are running Wilwoods all around is just like saying "I run calipers all around". If you know the MC size and the size of your pistons in the caliper, you can do some pretty simple math to tell you where you should be, and how much prop valve you need to throw at it.

That sounds to me like a few injectors are just going fully open above 1300rpm. I'll be interested to hear what the injector lab place says about them. Were you logging data on the ECU? Should be reasonably easy to see if you had trigger errors or a bad sensor. Good thing to check, but I don't think it's the root cause of your issue here. Another thing would be to try installing a dummy injector and see if you can run through the test modes on the ECU to confirm the ECU is at least sending a good command.

The erratic crank angle signal that would make the injectors that out of whack would result in a no-start condition on an ECU like the Haltech. My money is on the windings in the injectors. ECU might be the issue, but the voltage requirements of a low impedance injector should be within what is possible from the Haltech. Also, just to address some of the statements earlier, the Low/High resistance is a bit of a misnomer. The low impedance injectors, also called "Peak Hold" have a much higher opening voltage, and keep the injector at a base voltage while running. They'll send the injector a 2-4v signal, then sit at 1-2v. High Impedance injectors, also called "Saturated" are a simple on-off signal, at 0.5-1v. Hence how a "High" injector can be overpowered and burnt out by a "Low" signal.

If you want to go racing, go Koni 8610/8611 inserts or MCS. You wallet will be a little sadder in the short term, but you'll be getting a quality product. I've used AZC, they are nothing to write home about, and I saw a HUGE improvement moving to the Koni inserts. Likely the same basic product as the BC, Megan, Tein, Feal etc. A full Koni setup should be a similar price to the AZC stuff.

Interested on how you plan to do this.

Makes sense with how Edan recommended the the caliper situation. Good data for people with the stock brake setups.

Nice work!! That ratio works out nicely with the piston sizing you have. That's some valuable data you've collected as well about the prop valve, thanks for posting that here.

Oh nice! Those will be helpful to tune in the bias. I've seen some gauges that go in between the pads and measure clamp force at the caliper, but haven't used one before. Good luck!!

Depending on what is left in the factory system for the rear circuit, it might be alright. Drum rears use a lot less pressure than calipers, which might be why the rears seem to be oversized. Worth looking into more before cutting in the prop valve. I don't THINK Edan would flat out lie to you, but he might have made some assumptions about what you have going on. Also, it would be worth verifying based on the Wilwood boxes/part numbers your piston size, as the numbers listed on the Silvermine site don't correlate with the numbers on the Wilwood site. But parts change and I'm relying on photos that might be out of date!

Sorry, I know you didn't come here asking about your brake ratios, but the links you posted got me curious. I went through a similar sizing adventure, although I am able to use different sized master cylinders to solve my bias issues.

Ahh ok. You've got WAY too much rear brake. The front pistons are a bit of a mis-matched for the size of the rear pistons, fronts are small, rears are large, relatively speaking. Since the MC equally powers both brake circuits, the clamping force at the rear is higher due to the increased piston area. If you have any of the factory stuff in the brake circuits, this will alter your results. Right now, based off Wilwood's numbers for the Superlite front (4x 1.12" pistons) and the Dynapro rear (4x 1.38" pistons) you have a 60% rear bias. Ideally that would be flipped. If you max out that prop valve and cut the rear pressure in half, you'll end up with a 56% front bias. Couple links included below for further reading on the exciting world of brake pressure math! https://www.tceperformanceproducts.com/bias-calculator/ https://www.joesracing.com/master-cylinder-math/

I can tell you off the bat that you're going to need some serious help to get the rears to come in line, and even with a dual master setup, you might always have a rear bias with this setup. What master cylinder(s) are you using? On edit: You've linked two rear kits. What front kit did you get?

Hmmm interesting. From racing Z's for a number of years now, I think the idea that the mustache bar + diff mount will transmit a dramatic amount of lateral load under cornering is overblown. I'm sure there is some, and some FEA could probably tell us to a certain degree of certainty, but I'm also sure that there is a huge amount of flex in the rear of these cars from the factory. Once you start tossing V8's and big tires at these cars, all bets are off. I take a lot of reference from how the cars that these parts come out of are used. The S550 Mustang for example from the factory has bushings inset into the front of the diff, and the rear rides in another set of bushings. There are a number of kits for people who track the cars to solid mount the diff (aluminum bushings for the front and rear). A local autox friend of mine has this upgrade in his 2017 Mustang and is making about 850hp. No cracked diffs yet! Good points tho!! This is one of the more radical mods for the rear of the Z car, I'm excited to discuss and see if the community can improve it for V2!

So far the one event we've been able to run was a blast! Need to get used to it. Clutchless shifting is weird, but much faster. I'll have to see if I can find some RPM traces to illustrate. A bit advantage of this box was I get to select ratios. At the moment, it's geared for higher speeds, so a bit of a long first/second. Makes it tough in the little lot we were in, could have probably screamed around in just first gear. More strength, ability to swap gear ratios pretty easily, easy to R&R, and a teensy bit lighter. It is still in a H pattern (Jerico WC-4 if you want to go look at their website), but we aren't allowed to run sequentials is this class anyway. The springs for the 2-3 shift are crazy strong, I don't think there's much advantage to sequential at least for the upshifts here.

Stuck a gopro back there, saw em move. No rubber left in the bottom of my car, closest thing is the LCA pickup bushings which are delrin. I do think these studs are enough to hang the rear frame on as they've done. Most "modern" cars from Nissan (s13, s14, 300zx 350z) have similar methods for mounting their subframes. The only difference would be if the upper plate is thinner than on these newer cars. They also use 4x of these, with the rear frame connecting the points. It looks to me like the Apex piece attempts to solve this with the solid mounting in the front of the original LCA point. If anything, I'd add another brace in the front to finish boxing out the frame. Thanks Leon! I'll agree with you on the hard mount/soft mount business. I imagine the rear soft mounts (unless they are a delrin insert) are designed to accommodate some misalignment in the chassis? Unless they are a delrin or poly bushing they could be swapped out for aluminum. Looking at how the 8.8's are mounted in the S550 mustangs, this diff mount checks out, as the front two mounts on the diff have rubber isolators in them. There are also a number of kits that let you switch these to solid mounts if you want Ultimate Response (tm) haha. Toe out in a corner would be sketchy, but I'm not sure this system would allow for any more than the factory system. Something to test for sure. I still do really like being able to adjust your roll center, something nobody else is doing in the rear of these cars, at least at a retailer level.

I'd be interested to hear a more in depth discussion of why mounting the diff and rear control arms to the two largest pieces of hardware in the rear of the car (that go through the rear frame rails) isn't such a good idea? Maybe something that integrates the locating holes. On my car, the factory dropdowns were woefully inadequate. Pretty flexy in lateral loading, the only real thing preventing shift was pressure from the opposite wheel. It's even been suggested by several members on my build thread to connect the factory mustache bolts to the rear control arm pickup points for added stability in cornering. I've boxed the factory dropdowns, but potentially moving to an Apex style rear subframe for additional stiffness. I'm also intrigued by the rear control arm style this affords, using inner heim joints to free up bind, rather than the traditional bushed mounts. That lower mounting hole is probably too low for most cars, but if you went up with the car for rally use, might be helpful!

Instagram is rife with photos of their knuckles, control arms, front subframes. A little less so with these big rear suspension conversions, but they're out there. Makes sense for a part that costs a couple thousand dollars. https://www.instagram.com/p/B7-IwogJtBi/ https://www.instagram.com/p/B8Eizm5pSz7/ https://www.instagram.com/p/B9j1UvHnyoq/ https://www.instagram.com/p/B-N_tOFHCBG/ https://www.instagram.com/p/B-0kBOXntko/ I am personally using their tie rods and knuckles, after snapping a Arizona Z Car knuckle in half.

I think this is the gear lash in the transmission, new sound this year haha! Straight cut gear whine is a wild sound

I disagree. The different between taking peoples money and running off is and providing a product that people have actually received, installed and used is not subtle whatsoever. If you want to complain about no user install guide or a lack of user available FEA/testing numbers, that's a whole different can of worms that almost every small company in the automotive aftermarket is not going to be able to satisfy.

Mini update! We got one weekend of racing in before the world went into shutdown. Car did real well for both days, had a little bottoming out over some bumps in the front, guess that means we are low enough Getting a chance to do some more mods now. Couple cosmetic things happening, and getting the car ready for some time trial events that will HOPEFULLY be happening in late June.

I think comparing Senza Pari to Apex is a bit of a low blow. Apex has moved a large amount of product and Ohm is actually responsive to customer concerns. They are a business, rather than a guy. As far as documentation, they are on the same level as T3, which has been the standard for a long time in Z car aftermarket. From looking at Instagram and facebook, Apex is mostly selling front subframes, control arms and steering knuckles, makes sense they wouldn't be selling a huge amount of the conversion kits.

The standard flares are VERY thin. I've blown my set up multiple times, I'd go for the special next time. Streeter is great, he'll deal with standard companies in Japan, not just bidding. He's particularly good at making sure you get what you expect to get. Very fast shipping, EMS is usually about 1-2 days to the west coast. Prices can be better than RHD Japan, usually comes in about the same.