Sunday, July 29, 2012 - 08:39 pm, by: Ben Lipman(Ben12a)
I bolted the car back together and went out to open practice yesterday with it as is. I just wanted to drive the thing so I remember why it is in the shed.
Had a good day. Only did three sessions of the six due to the fact I spun off into the gravel and filled the bead of one tyre full of rocks and crap. The rears were shot, but a Mazda dumping the contents of its sump on the track didn't help.
The good news is my wing and dodgy end plates all held together with no signs of 'wobble' that I was afraid of. The side skirts and undertrays all stayed on and appear to have no damage on cursory inspection.
The bad news is the rear end 'chattering' under brakes is back. I had it softened up for the wet session. Every time I went hard for the brakes the rear would get what can be best described as axle tramp and try to turn the car around. I went back to a regular setup for the next dry session however it was as bad, if not worse. I did not get to the bottom of it as once the mazda oiled the track and I damaged my tyre I decided to call it a day rather than chance the tyre going flat (it hasn't yet, LOL)
Some pics:
Andrew McKellar DieHard NSW Soarer Sports Sedan (well, nearly)
Monday, July 30, 2012 - 08:25 pm, by: Allan Langford(Allan)
I found pushing mine till the front brakes cooked the back brakes where still ok causing the rears to try and lock... thankfully still got ABS on mine, I just did a couple of cool down laps and the front's come back.
do you have any data logging on the car?
Ben Lipman Goo Roo SA Soarer TT manual, plus TT track car
Monday, July 30, 2012 - 10:26 pm, by: Ben Lipman(Ben12a)
I think the wing needs some more angle of attack. It sits quite flat as is. I was hoping it would be enough, but with no data on the wing it is all guesses. I'll make up some more adaptors with more adjustment range. Currently I am using the ones that West threw in (the uprights sit more vertical in their application). Did it help? Despite the ruined rear tyres I am up about 4kph from testing earlier in the year through the kink(to 196kph) on the same tune.
I went back to my original idea of making a ladder frame out of steel down to that rear box section. That combined with the threaded rod cross pieces have made it a lot more sturdy. Is it the final solution? No. I just wanted to go drive the car so used scrap lying around the shed.
Lap times are comparable to last year (1:22 ish) before my break through to 1:19. I haven't driven much so there is probably a lot more gains in the driver to be had. Plus there is no confidence to go deep with braking when the rear is playing up so bad.
Yes that is my back yard. It does look a bit like a park from that angle. The missus would be flattered. She does most of that work.
I think I may have broken a few Sports Sedan rules. Bonnet, skirts, front bar, guards...
Allan- no data aquisition beyond the racechrono lap timer. I can get a speed trace and overlay laps with that, but that is it. The Haltech PS2000 has some data logging capability, but I do not know how to access it. I was going to get the racepak dash (plug and play with the Haltech) for my birthday but after some recent criticism from guys out at the track about the lap timer/GPS function I have decided to wait to see if Haltech improve it. Apparently no one is getting reliable signal, even in open wheeler cars. I get 7-10 satellites when parked in the garage at the track with my trusty nokia/Qstarz setup. All for less than $160 too...
I am going to check the mechanicals at the rear of the car for obvious faults first, but I am wondering if the tune might be causing the chattering. There have been a lot of changes to the front undertrays, splitters, and a harder pad as well between my nice, deep, reliable, predictable braking package when I ran 1:19 and what I am experiencing now.
I was going to change back to the old faithful Intima SR6300 pads but went off and called it a day. I'd have to go back and look at my notes, but I think the rear end was playing up with the old pads in last test day also.
I'll post up some photos of the wing mounting when I find them on this 'puter. The data drive seems to randomly appear and disappear when it feels like it. Very annoying.
Dan McColl Goo Roo Victoria (The Nazi State) Pretty Red Thing and The Black Rattler
Tuesday, July 31, 2012 - 08:20 pm, by: Ben Lipman(Ben12a)
All good suggestions as usual Dan.
The problem is I am not that good a driver to be able to just change the way I downshift. Years of doing it one way. I know I should try, but always get lost in the heat of the moment with those higher skills, LOL.
Decel fuel cut- might have to talk to Morpowa about that. If I adjust my throttle stop so it remains partially open next time I am at the track, could I test this out without a trip to the dyno?
As for the stiffer front dampers- The settings are within a click or so from last year. Surely they can't have that much effect? Maybe the more efficient and much larger front diffusers are affecting this also?
One suggestion from a spectator on Saturday: he thought the front splitter was getting bloody close to the ground when the chattering was occurring. There is some small possibility the splitter/diffusers are getting stalled when the gap closes too much causing a sudden loss in front downforce. From what I have read this can lead to 'porpoising'. I can't feel any porpoising, just the rear end chattering before trying to overtake the car.
Wednesday, August 01, 2012 - 09:32 pm, by: Dan McColl(Hoon)
You'll need to learn heel/toe. I'd say this is the main part of the problem.
When you downshift without blipping or revving the engine up, when you let the clutch out after the downshift the engine is working like a handbrake and basically trying to slow the rear wheels down to whatever speed they'd be doing at idle (20-30km/h) while the car is doing 100+.
Combine this with the forward weight transfer under braking while the rears are already light then it's not hard for the engine braking effect to overcome the rear traction and therin lies the issue.
What you've got is basically like reverse axle tramp.
What you need to do is sorta roll your foot off the side of the brake pedal so the side of your foot presses the throttle during the downshift (while the clutch is depressed).
If you have a G25 or 27 you can practice this pretty well at home playing games.
Ben Lipman Goo Roo SA Soarer TT manual, plus TT track car
Wednesday, August 01, 2012 - 10:11 pm, by: Ben Lipman(Ben12a)
WTF is G25 or 27? I don't play games.
I can 'heel toe'. Not great in the Soarer as the pedals are awkward, and I'll admit it gets missed under duress a bit.
My issue is: why has it all of a sudden become an problem? Why, in the same car is it now causing me so much grief?
After Googling for a couple of hours there are some areas to look at: broken component in the suspension; worn cradle/diff bushes; deceleration tune issue; brake balance (not sure how this could have changed); tyres (the rears are worn); and of course, me.
I simply don't have the time at the track to sort out a lot of things like I did in Darwin. I had very good access to Hidden Valley up there as I was 'in' with a few of the IPRA guys and our club ran the events there. Getting the keys for private practice was not a problem.
I don't even have time to get under the car at the moment with work, sport, kids, house. It is like a reverse mid-life crisis (where my irrational, selfish pastimes make way for proper, responsible living, LOL) I am seriously considering shelving it all until I can find the time to do it justice. Save my dollars in the meantime. Or find a club that does Motorkhana again.
Dan McColl Goo Roo Victoria (The Nazi State) Pretty Red Thing and The Black Rattler
Tuesday, August 14, 2012 - 03:11 pm, by: Paul Kalie(Ajzs)
Mate , spoke to Simon at WTAC and the guys at the Haltech stand both said that the rear locking has nothing to do with the Decel 100% adamant about it.
P.S come and finish my car !!
Dan McColl Goo Roo Victoria (The Nazi State) Pretty Red Thing and The Black Rattler
Tuesday, August 14, 2012 - 06:52 pm, by: Ben Lipman(Ben12a)
Cheers Paul and Andrew. I would happily come and spend your money working on your car. I did offer last time I was over there, but your were all caught up with getting married...
A set of Costa's aluminium diff and cradle bushed arrived today. Might help. So might new tyres, but I CBFed until I finish fiddling around with everything else.
I have also taken to heel toeing every down shift in the road car regardless of where and when I am driving to try and build that 'muscle memory' so that it becomes an automatic action.
I'll work through the problem until it is resolved.
Peter Nitschke Junk Filterer South Australia UZZ30 UZZ31
Saturday, August 18, 2012 - 07:53 pm, by: Ben Lipman(Ben12a)
Thanks Peter.
I made up some new end plates for the wing from a sheet of 3mm pure carbon fibre I bought from China. Dodgy buggers tried to sting me a $30 fee to "avoid big tax for you". I told Johnny Chinaman he could refund the cash and I'd report him as a scam. He decided I didn't need to pay a $30 fee after all.
I got under the car today with the intention of fitting the rear diff and subframe bushes I bought from Costa. Whilst under there I decided to check every thing I could. Unfortunately the left traction rod is loose as all buggery. That is, the bushes are kaput. There is 1-2mm of forwards backwards movement in the hub/upright and traction rod. It can't have been helping the axel tramp.
I have decided I'll replace the traction and toe rods with Costa's bits. I am also looking at that big heavy twin exhaust system and wondering what a 3 inch single with one/no muffler would go like. Turned a weekend job into an epic build again...
Ben Lipman Goo Roo SA Soarer TT manual, plus TT track car
Saturday, August 18, 2012 - 08:00 pm, by: Ben Lipman(Ben12a)
Dan McColl wrote on Tuesday, August 14, 2012 - 06:51 pm:
I thought you'd have long(ish) hair for some reason.
LOL. I just read this. Mum never let me have long hair as a kid, and I just got used to it. I would wear a crew cut if the missus would let me. She reckons having my hair so short makes me look old. I tell her she has long hair and still looks old
Monday, August 20, 2012 - 07:35 pm, by: Ben Lipman(Ben12a)
G'day Daniel.
Mallala don't seem fussed with noise levels. Darwin had a rule, but never enforced it. Sydney tracks were more strict, being a 92 or 96Db limit. Qld is the same I believe. One of the track I visited (Wakefield or Darwin) had some policy about needing a muffler to prevent grass fires...
Most events I have entered state either 92 or 96Db measured at 30m, so I would aim to meet that standard.
I currently have custom dumps, 3 inch front pipe, 3 inch mid pipe into twin 2.5 inch pipes and Trust straight through mufflers. No cat. About as high flow as you'll get on a twin system.
I want to go 3 inch all the way through a single muffler. Mostly to save weight and increase noise. The car would easily pass emissions (noise) testing as a streeter, LOL. (this system plus a cat used to be on the road car).
Ben Lipman Goo Roo SA Soarer TT manual, plus TT track car
Sunday, August 26, 2012 - 06:11 pm, by: Ben Lipman(Ben12a)
So I got out the welder today and made up a 'new' 3" straight through exhaust. I had to buy a 90deg mandrel bend, an new 2 bolt flange, and found a second hand 3" Apexi cannon locally for $50. All up I spent less than $100. The bige bonus: The twin 2.5" system with Trust mufflers weighed 21.5kg. The 3" single with the Apexi weighs 9.5kg. The actual muffler is the heaviest piece. Stainless is heavy.
It is bloody loud. Not much quieter than it was with no exhaust. I might have to actually buy a decent straight through muffler, perhaps one of the Hooker Aero Chamber currently on ebay for $100.
I should have been doing the diff and subframe bushes, but that was too much like hard work. I got the diff out, burnt out the old bushes and fitted the new ones, but the rear diff bushes in the subframe need some more effort.