R33 Gtst Track Build

[Dale FZ1]

Anytime you're in Queensland, no problem.

This thing still exhibits some understeer. Setup helps to dial quite a bit of that out but the physics of a nose heavy barge won't be ignored when it comes to direction change and holding a tight line.

Rear end tyre slip can be addressed without too much problem (I think) so the first port of call will be ride height and a little bit more toe-in.

[Dale FZ1]

Edited June 9, 2015 by Dale FZ1

[Dale FZ1]

Mighty quick tarmac rally car that Subaru, traction on launch, and drive off every corner.

Thanks to Duncan for his tech advice on how to post this youtube stuff. Edited June 9, 2015 by Dale FZ1

[Dale FZ1]

Practice laps Morgan Park Circuit K

more practice, trying out the QStarz data logger. Relatively easy tool to use but painfully slow process to combine the data with video and create the end product.

I think the real benefit of the logger is to use the software to compare laps and driver behaviour. $200 makes it a cheap addition to the race kit, and accuracy is fine for club motorsport purposes. Edited July 23, 2015 by Dale FZ1

[Dale FZ1]

Setup for this event wasn't changed by a large amount. Rear ride height was dropped 15mm and we trialed sway bar spec to see what worked. Ended up dropping a link out of the rear bar to effectively remove its impact on suspension and handling.

All relatively small changes that have given a pretty noticeable increase in both front and rear end grip. Not much understeer or oversteer, pretty good as far as barges go.

[Dale FZ1]

Final round of the QSSS A Series ran 2 weeks ago, far better weather than experienced for Round 3 in July. No arctic chill this time around.

Decided to play more with suspension setup to see if we can achieve better drive off corners and dial out a bit of oversteer. Following advice from MCA, reconnected the rear sway bar and used Friday practice to experiment with rear spring rates. Tried out 2 lighter spec and the overwhelming characteristic was understeer. So we reverted to the 5kg rears for a better overall balance and decent mid corner front end grip but and just drive around the relative lack of rear grip. The lighter rear springs did give improved rear grip but just couldn't work with the heavy fronts we are currently using.

Saturday brought consistent times and predictable handling but the rear traction and stability was costing time.

Previous experiment by disconnecting the rear sway bar was good, so decided to leave it in place and drop rear ride height by 5mm to see what happened. Doesn't sound much, but it really hurt the good turn in and mid corner front grip. And the oversteer on exit was still there...

Just drove to what it was doing, with a bit of commitment. Despite the handling being worse, the car was 2.5 seconds/lap quicker than Round 1 earlier in the year, or just over 1 sec/km for the rally-minded. The extra speed I attribute to newer rubber and more driving consistency. But we have identified the next spec to trial which will be slightly lighter springs both front/rear, and lifting the rear ride height that 5mm.

Got one of the final runs uploaded with data overlay from Sunday, couple more to come.

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[Dale FZ1]

Here's Saturday, run 3 on a warmer track. Car responded to the helm much better in that trim.

Steady improvement to car and the driver's head will see times fall, and consistency between laps lift.

[Dale FZ1]

Got a few updates on plans and experiences following season's end:

Decided to go testing at Queensland Raceway, resolve what can/should be done to get closer to the desired suspension setup. Tried a 13kg/4.5kg spring combination with same ride height and alignment as we last ran the car. Stock sway bars. And a set of Hankook Z221 front (nearly new), and rear (brand new) both soft compound.

Learned that QR is not an inspiring place to drive, fairly sterile. I don't think it places huge emphasis on agility and direction change but the straights allow bigger hp cars to shine.

Also learned that the 13/4.5kg combination isn't as good as the 14/5kg setup. Seems to kneel over on the outside front tyre in corners. Might go to a 0.5 - 1kg increase front/rear because we need to maintain balance. Those numbers are nowhere near looking like they're in sync with what other R chassis runners are using, but I am taking advice/recommendations directly from MCA. Who better to advise than the man who's designing and building the shocks?

Brakes finally had enough of track work. The front rotors had been showing signs of heat. Stress cracks throughout the swept area, although did not look unusable. The rears however, did not survive the day. A crack right through the swept area was enough to encourage us to pull the pin. And discuss brake spec. The Winmax W7/W3 pad combination were exceptionally good, well worth the spend. The W7 tend to be quite "bitey" and require progressive pedal application to get results without causing them to nip up. No ABS on this car, and even with bone stock OEM spec rotors and calipers, the brakes are very very strong but maybe lacking the tendency to telegraph any impending lockup.

Result: front braking hardware upgrading to Evo 5 Brembos and Evo 10 Rotors 350mm. Fitted up using Alpha Omega bracketry. Brake bias adjustability to happen via a pedal box arrangement with balance bar. Researching options on that one ATM, will post up a bit more when it becomes evident what line we go. Again, taking advice rather than try to muddle my way through it. Rear brake hardware spec not changing. Stock R33 rotors, calipers, and some new W3 pads.

Engine-wise, it has run sweetly. But did some testing on dyno to gauge what might be a good thing. Acquired United E85 race spec fuel. Fitted a 10 micron filter to replace the Z200 filter. Homework told me that the fuel system may struggle to feed the fire especially with "decent" boost levels. Bosch 044 with big wiring and 14.0 volts at the pump, and some 700cc injectors. On pump 98, going from 16.5psi to 21psi lifted output by a consistent 75hp across 4000-7000. There were issues getting the car tied down on the rollers correctly for a pretty print out, but that's going to be a fairly repeatable 460-470rwhp. The physical size of the 0.6A/R compressor cover showed as a limiting factor but I was happy with how effortless the extra hp was made.

Then set about draining the tank, refilling with E85, and tune using a target 16psi due to questionable fuel system flow capacity issues. With E85 friendly ignition mapping wound in, the two curves overlapped nearly exactly. And the signs appeared that the 044 fuel pump wasn't able to keep up. Time to investigate a Walbro setup.

All things being equal, E85 is now likely to be the direction we go for 2016.

I'll try to get a few pics up of the above, when taken/available.

[rcs_888]

How have you gone with MCA? Ive been debating going with them but looking into supashok atm being a local SA company makes it nice for me lol

[Dale FZ1]

For me there's no debate.

MCA do a quality product and the Red spec have worked very well for me. Backup and assistance are first rate. There is an exceptionally broad pool of knowledge/experience drawn on, evidenced in their results with the WTAC Hammerhead.

I reckon it shows through in these products.

[rcs_888]

Yeah that would work for you as mca are local for you arent they? Supashok are local for me so that will be helpful. Im keen to get mine on the track next year this years been a write off just building the car

[Dale FZ1]

Time for pre-season maintenance and a couple of planned upgrades.

Front rotors had really done very good service, and for me there is strong evidence that there is very little wrong with stock R33 braking hardware, provided the well worn path of high quality pads, fluid, braided lines and BMC stopper is followed.

Couple of seasons running and the front rotors were covered in little stress risers, but they sure weren't performing badly.

I did decide to try something different from what I had, and went with the Evo Brembo / Alpha Omega / 350mm rotors up front. I hope they're something pretty good out of the box, because with a 1 piece DBA rotor there is a decent amount of extra weight added. Some good reviews so far says they should do the job a bit better.

The other thing I decided to do was to chase some adjustable bias. Did not feel that the suggested 1 1/16" BMC change was going to achieve anything more than a shorter pedal. I'm not expecting this to go together too quickly but I expect the results will be worth it.

Edited January 27, 2016 by Dale FZ1

[timmy_89]

Nice to see you have rhe fromt kit fitted up. Keen to see your opinion with the brake bias setup

[Dale FZ1]

We felt there were bigger gains to be had from adjustable bias than the rear Brembo kit, considering the relative component costs. My front rotors had obviously had a fairly serious workout, while the rears weren't stressed the same way. So I think the conclusions are fair.

I'll be giving some updates as this kit goes in and run. I expect some teething issues (ie master cylinder sizing) plus a few fabrication challenges just fitting it all up. I will say up front that I don't think this is for everyone. Someone's got to have a go, and plenty of cars other than dirty old R chassis have had pedal boxes fitted before now.

[k_d]

What pedal box did you go with?

[Dale FZ1]

The picture shows it.

Tilton 600 series underfoot MC.

[rcs_888]

Do you know what master cylinder size your going to be going with? I have the underhung reverse mounted tilton pedal box im thinking about getting a pair of 15/16 and pair of 1" masters. The bm44 is 15/16 and the bm50 is 1" and i know that my alcons have a slightly larger piston area than the r34 gtt calipers. What route are you thinking of going?

[Dale FZ1]

I'm going with 7/8 and 3/4 MC. They give a calculated 70:30 bias F:R. We won't know how that translates to pedal travel until it's in and plumbed but it should be a reasonable starting point.

Going to test those two sizes for clutch MC and be a bit more informed when ordering the third unit.

Not sure I would follow the factory BMC sizing particularly because the pedal box will probably have a different movement ratio (leverage) than what the factory specified. It's definitely a juggling act for pedal travel vs weight vs feel.

I'm going through the plumbing process ATM. Necessarily slow because I want to get it right, without buying unnecessary fittings. Earls aren't cheap.

[rcs_888]

Hmm yeah i didnt think about the ratio of the stock pedal... hmm might have to wait till yours is done

[Dale FZ1]

The pedal box was completed the day before practice for this weekend's sprints meeting.

Average quality pics however there's enough detail to show what was done. Cut a hole out of the floor and welded in a box section, stitched to the chassis rail underneath. No flex in that...

Unfortunately, playing with sheet metal required fuel lines to be re-routed so out came the originals and new ones were routed through the cabin along with the required bulk head fittings. Including all fittings and hoses, that added a few hundred $$ to the job.

Fabbing up a throttle linkage used a combination of Tilton bits and a rocker arm made out of aluminium plate. All low friction stuff with proper bearings.

Reservoirs were fitted under the bonnet, due to lack of suitable places to mount them under/behind the dash. Best bet would be to follow the idea of guys ditching the original dash and free up room and do things simpler than I have.

So far, here's my opinion on the setup:

Floor hinge action feels different, but you quickly get used to it. Anybody who's driven old Volkswagens will be right at home. The pedals can be adjusted up/down and sideways to suit preferences and feet sizes. It's an easy way to alter the leverage ratio and it seems this Tilton gear is well thought out.

There are definitely some tricks to getting the balance bar positioned right, bearing in mind that is just a starting point and you will adjust from that point. Tilton offer some good literature, probably enough to get a competent person headed in the right direction. However there's no denying the benefit of experience and I've been fortunate to consult with a very knowledgeable engineer.

In practice, the whole setup works pretty well but I'm thinking the master cylinder sizes may go smaller. Pedal effort is currently very high and you've got to really step on them to get proper braking action. Actually the harder they are stood on, they begin to come into their own from a "feel" point of view. No brake lockups, the system talks to you. Smaller master cylinders, longer pedal travel and improved modulation sounds like a good move. The caliper/rotor/pad combination is a good one, and it just works.

What's good about this setup is that we got a good initial result, but it will get better the more we tweak it.