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Ben Lipman
Goo Roo
SA
Soarer TT manual, plus TT track car, plus a spare shell

Posts: 3764
Reg: 04-2006

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Wednesday, July 02, 2014 - 12:16 pm, by:  Ben Lipman (Ben12a) Edit Post Delete Post Print Post   View Post/Check IP (Moderator/Admin Only) Move Post (Moderator/Admin Only)

As if I have the skills to photoshop something. As if I even have photoshop. Haven't you seen my MS Paint renderings, LOL?

The car is now pretty much ready for a test day at Wakefield park tomorrow at their 'speed off the streets' day. Weather is mostly fine, however if today is anything to go by...it is lunch and the fog still hasn't lifted here in Canberra. Hopefully get some decent weather at Wakey tomorrow.

Had a little setback: not long after the photo above was taken the car fell off a faulty jack. The front wheels were on the car, and I was about to put the rears on. In the process of transferring the stands at the rear the jack failed, causing the car to come off the stands at the front. I destroyed my nice new oil cooler, the intercooler pipe, and the headlight/radiator subframe is a bit bent.


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On the upside, I got to do some panel beating using a tow ball, jammer, and parts from the offending jack.

The oil cooler does not leak, however I cannot risk an engine failure due to the cooler failing out on the track, so I have retro fitted an older, smaller cheapie oil cooler.


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I also put the gearbox back together with a new gasket, shifter bush, and shifter seat. It turns out I did not have much of a shifter seat at all, only the washer from the bottom. Needless to say the shifter feels great now. I thought it was pretty good already compared to the red car so I guess I should have a look at the road car at some stage...


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Matthew Salkeld
TryHard
South Australia
1JZ powered 180sx

Posts: 229
Reg: 07-2008

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Thursday, July 03, 2014 - 08:30 am, by:  Matthew Salkeld (Munkymatt) Edit Post Delete Post Print Post   View Post/Check IP (Moderator/Admin Only) Move Post (Moderator/Admin Only)

got any pics of the 1nz coilpacks installed? I was hoping for any feedback that you might have had from that.
Michael McKellar
TryHard
NSW
Mini

Posts: 125
Reg: 08-2008

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Thursday, July 03, 2014 - 07:56 pm, by:  Michael McKellar (Mickmini) Edit Post Delete Post Print Post   View Post/Check IP (Moderator/Admin Only) Move Post (Moderator/Admin Only)

Lucky it was not your head!
Ben Lipman
Goo Roo
SA
Soarer TT manual, plus TT track car, plus a spare shell

Posts: 3765
Reg: 04-2006

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Thursday, July 03, 2014 - 08:10 pm, by:  Ben Lipman (Ben12a) Edit Post Delete Post Print Post   View Post/Check IP (Moderator/Admin Only) Move Post (Moderator/Admin Only)

Matt, I haven't fitted them yet. When the engine let go I put all my effort into getting that sorted. That means I am still running the supersparks, with plugs gapped down to 0.5mm. This is working, but you would have to imagine it is costing me some performance. I think I'll put them in when I have a bit of cash to throw it on the dyno at Ultimate Tunes so they can adjust the tune if there is any advantages to be had.

I expect they will be fine, and I have noted Goleby's etc are selling them as a kit now.

Michael - yes. I have a sore shoulder. I am not sure if part of the car hit me, or if I just tried to shoulder press it when it started to fall. I know of three people who have died under cars supported by jacks this year. Mine was on stands, but I was using a jack that had failed previously, which in my mind is just as stupid.
Andrew McKellar
DieHard
NSW
V8 Soarer Sports Sedan

Posts: 735
Reg: 06-2008

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Thursday, July 03, 2014 - 08:59 pm, by:  Andrew McKellar (Toymax) Edit Post Delete Post Print Post   View Post/Check IP (Moderator/Admin Only) Move Post (Moderator/Admin Only)

Some photos from today. Ben, up to you to describe what went on each session, based on your notes. I will send you all 1035 photos from today in high resolution so you can analyse them with your data.

First session was bedding in brakes only. Second session:


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Third session:


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Fourth session:


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Lots of photos from sessions in between, but not much noticeable change from the outside. Skip to last session:


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We need to look at ride height, rake and roll centres next. I'm not happy with the sunlight seen under the car.

Some good work today with rethink of which gear to be in at certain places. Go through your data carefully and you will find a bunch of good segments that will add up to a great theoretical fast lap. Then think about apexes, lines and left foot braking in places.

A good and productive day, thanks for the entertainment.
Ben Lipman
Goo Roo
SA
Soarer TT manual, plus TT track car, plus a spare shell

Posts: 3766
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Thursday, July 03, 2014 - 09:32 pm, by:  Ben Lipman (Ben12a) Edit Post Delete Post Print Post   View Post/Check IP (Moderator/Admin Only) Move Post (Moderator/Admin Only)

I have a brake light out....




I have been sitting here trying to figure out the Haltech Data. I have a Haltech Data Log Viewer but can't get it to work. I can see the data in the RacePak DataLink program, but I am assuming the Data Log viewer is more user friendly...if you can work out how to use it.
Ben Lipman
Goo Roo
SA
Soarer TT manual, plus TT track car, plus a spare shell

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Thursday, July 03, 2014 - 10:06 pm, by:  Ben Lipman (Ben12a) Edit Post Delete Post Print Post   View Post/Check IP (Moderator/Admin Only) Move Post (Moderator/Admin Only)

Not sure how this will turn out, but this is the data from me bedding in the brakes during the first session, and then deciding to go for it in lap 4 and 5. Theoretical fastest lap is 1:07.647. The actual fastest lap is 108.979.

If you look at the theoretical fastest lap segments, a lot of them are from that lap number 5. If sector 2-3 had of been better she would have been a good lap.

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Andrew McKellar
DieHard
NSW
V8 Soarer Sports Sedan

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Friday, July 04, 2014 - 07:16 am, by:  Andrew McKellar (Toymax) Edit Post Delete Post Print Post   View Post/Check IP (Moderator/Admin Only) Move Post (Moderator/Admin Only)

What I see there is a heap of throttle applications that are not related to car speed. They're the bits where you're power sliding out of nearly every corner. We got rid of the power sliding by balancing the car better and using different gears. Now the driver has to get used to a new way of driving. You'll go faster with the car balanced and maintaining traction, I promise.

Don't forget that with each new session I loaded you up with new things to think about. You achieved new gear selections in places you never have before, you achieved throttle blipping, you started getting deeper under brakes and not rolling out of the throttle, you achieved some excellent lines and apexes. The lap times will come when you get used to driving this way.

Go through all of your data for the later sessions and you will see quick segments there. Check your speeds at various points on the circuit and you will see that you were quicker in lots of places.
Paul Kalie
TryHard
NSW
TT

Posts: 151
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Friday, July 04, 2014 - 03:33 pm, by:  Paul Kalie (Ajzs) Edit Post Delete Post Print Post   View Post/Check IP (Moderator/Admin Only) Move Post (Moderator/Admin Only)

Ben have you played much with rear ride height ? Alot of the pictures show a nose down attitude be it under heavy brake application. Just thinking back how the early RX7's like a bum dragger ride height and was wondering if this is something that might help settle the rear on turn in ?.
Ben Lipman
Goo Roo
SA
Soarer TT manual, plus TT track car, plus a spare shell

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Friday, July 04, 2014 - 05:12 pm, by:  Ben Lipman (Ben12a) Edit Post Delete Post Print Post   View Post/Check IP (Moderator/Admin Only) Move Post (Moderator/Admin Only)

I am running a small amount of rake front to rear for the free downforce/reduction of lift. The comparison to early Rx-7s is problematic as they had a live axle/coil spring rear end. I think if I moved to a nose up attitude the weight shift from rear to front under braking might actually increase. You are correct in that it might aid in weight transfer over the rear wheels though.

I have spent the day pouring over the data and referring back to texts. Quite a few hours were spent last night making the data mean something to me. I have now got the racepak breaking the track into segments that resemble the track map. That is: there are now 10 corners in the data, as per the official Wakefield park track map unlike the four corners that were generated by the Racepak automatically based off g loadings. Now I can look at a sector and immediately relate it to part of the track.

The frustrating thing about the day yesterday was that the times didn't vary a great deal from one setting to another. It was hard to get a read on what effect the changes were having. For example: session number 4 had the most consistently fast laps - 5 out of the six fast laps were 1:09s with three of them being 1:09.2 or better. Other sessions had fast laps, but only 1 or 2 out of 10 laps were in the 1:09 range and the rest were 1:12 etc.

Today I built/repaired/modified a new alignment rig as my old one was cumbersome and fragile - it was somewhat bent when I went to use it at the track on Thursday. Here are the figures I pulled from the car today.

FRONT
Total toe: 5mm toe out.
Camber Left: -2.0 deg, Right: -2.5 deg
Ride height L: 355mm , Right: 350mm

REAR
Toe total: 1.5mm toe in (1mm left, 0.5mm right)
Camber Left: -0.5 deg, Right: -1.5 deg
Ride height L: 347mm , Right: 351mm

You will note the right front and left rear ride heights are the lowest. This makes no sense. Generally if the right front is low, it would tend to raise the left rear. Due to the amount of fabrication that has occurred I no longer trust the CWG method of measuring ride height. I have three carbon guards and one flared steel one, all built to unexacting standards. I need to come up with a new way to measure the ride height to ensure it is even. Suspension mounting points make sense, but are not easily accessible. the chassis rails are not really accessible either. I need points that were built by Toyota and have not been molested by me or 21 years of abuse.

Something we did not play with were toe settings. I have always run approximately 4mm total toe out at the front. I liked the feel of it and it helped with turn in back when the front aero was minimal, and there was no power causing issues with rear traction. It might be time to either reduce front toe out, or go to a tiny bit of toe in to try and reduce the oversteer issue that I now have.

The results with the rear sway bar disconnected are interesting. Compared to the fastest lap of the day in the morning; my corner speed was up 8-10 kph through turns 1,2,3 and 4 but down in turn 5. Turn 6/7 (down the hill into the fish hook) was considerably slower, approximately 10kph. The straight between 9 and 10 was 15kph faster and the rest was about the same. I am going to fit the factory rear bar before I head to the track next.

The next outing will be a way off. It appears I have been ripped off by the 'business' that I purchased new front pads through. This combined with the damaged oil cooler means I effectively lost $800 in a week. I don't have any cash left in the budget...I could afford the 100L of fuel and entry fee for a test day but could not afford to buy lunch with the change. Time to save some dollars. It is a pity, as I feel that I need to be in the seat as I am just getting myself back up to speed, let alone the car.

screen shot of session 1 best lap (green) compared to session 7 best lap (red).

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Spencer Cameron
TryHard
NSW
JZZ30

Posts: 327
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Friday, July 04, 2014 - 06:06 pm, by:  Spencer Cameron (Switchio) Edit Post Delete Post Print Post   View Post/Check IP (Moderator/Admin Only) Move Post (Moderator/Admin Only)


Ben Lipman wrote on Friday, July 04, 2014 - 05:12 pm:

I have spent the day pouring over the data and referring back to texts. Quite a few hours were spent last night making the data mean something to me.




It'd probably be a lot easier to use the data log to simply quantify what you see in the video (assuming there is some) rather than trying to interpret raw data. At least to begin with..
Ben Lipman
Goo Roo
SA
Soarer TT manual, plus TT track car, plus a spare shell

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Friday, July 04, 2014 - 09:53 pm, by:  Ben Lipman (Ben12a) Edit Post Delete Post Print Post   View Post/Check IP (Moderator/Admin Only) Move Post (Moderator/Admin Only)

I only have video of two and a bit sessions. I am out of practice with track day administrative requirements.

After some more playing around tonight I have realised you can import video straight from your SD card (out of a GoPro for example) into the Racepak Datalink Program and then with some fiddling synchronise it with your data. You can then watch your video and have the data graph play in real time. So best of both words. I can see what I am doing inside the car, hear the engine, and see the data all at once.

If I buy the trackvision software ($149) I can superimpose the dash, a trackmap, g meter and lap times ect onto the video footage. It might be worth the investment.
Ben Lipman
Goo Roo
SA
Soarer TT manual, plus TT track car, plus a spare shell

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Saturday, July 12, 2014 - 12:10 pm, by:  Ben Lipman (Ben12a) Edit Post Delete Post Print Post   View Post/Check IP (Moderator/Admin Only) Move Post (Moderator/Admin Only)

After re-reading the spring rate section of a couple of text books I decided to work out the 'motion ratio' and 'wheel rate' for the front and rear suspension. The authors focus on wheel rate, not spring rate. To find the wheel rate you need to know the motion ratio of the wheel to spring. I measured the movement of the wheels for 10mm of movement of the shock/spring. For the front (bearing in mind I have longer than stock LCAs) I came up with a motion ratio of 17mm wheel travel for 10mm shock travel, or 1.7. The rear was 12mm wheel travel for 10mm of shock travel, or 1.2.

The wheel rate is determined by the formula:

wheel rate = spring rate/(motion ratio)squared

for the front I got: WR = 18/2.89 = 6.22kg/mm

for the rear I got: WR = 9/1.44 = 6.25kg/mm

If you like your rates in lbs/in it is 350lbs/in front and 348lbs/in rear.

Either way it is pretty damn close to even front and rear. I will do a bit more reading over the next few days to determine if there is a desired or magic balance front to rear with wheel rate. My intuition is that you would probably want the wheel rate a bit higher at the front, lower at the rear. If the preference is even front to rear, it seems we have 'fluked it'. Carroll Smith simply says he uses the softest rear spring that keeps the car of the ground and balances the handling with the optimum front springs. Food for thought.

I have also measured the ride heights using the procedure specified in the workshop manual, namely measuring from the centre of the LCA pivot to the ground. (front pivot on the front suspension).

Factory ride heights are: 194mm front, and 252mm rear. Note there is a 58mm difference front to rear.

My current ride heights are: RF161, LF 162, RR 228, LR 226mm. The average front is 161.5mm and average rear is 227mm, with a 65.5mm difference front to rear. This means I am running 7.5mm more rake front to rear than the factory specs.

Now that I know the motion ration of the shock to wheel, I can accurately predict the amount of adjustment to get the ride heights even, reducing the tiresome procedure of measure, jack up, adjust, drop, measure...

The next step it to get the left to right level (with my 90kg in the seat) and then take some of the rake out of the car - maybe 7mm so I end up with the factory specs. This should help weight transfer to the rear under acceleration, and may help with some of the dive experienced previously.

After looking at the data, I think removing the sway bar did not help, so the current bar can stay on for the moment. This is also influenced by the fact the rear diffuser is riveted to the diff cradle, making it impossible to remove the roll bar without removing the front of the diffuser.

I am looking at getting some more springs to try as there is a guy in Adelaide selling off a whole bunch at $80 a pair. Might get a slightly stiffer rear spring and a slightly softer rear spring to try. Changing springs at the rear is about a 30-45 min job, meaning it is do-able between sessions on your average track day.
Andrew McKellar
DieHard
NSW
V8 Soarer Sports Sedan

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Tuesday, July 15, 2014 - 05:09 am, by:  Andrew McKellar (Toymax) Edit Post Delete Post Print Post   View Post/Check IP (Moderator/Admin Only) Move Post (Moderator/Admin Only)

Excellent work. You love your formulas, huh. And if all that fails you could always just drive faster...
Michael McKellar
TryHard
NSW
Mini

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Tuesday, July 15, 2014 - 09:07 pm, by:  Michael McKellar (Mickmini) Edit Post Delete Post Print Post   View Post/Check IP (Moderator/Admin Only) Move Post (Moderator/Admin Only)

Also make a note of how many turns of the adjusters result in how many mm of ride height. This makes changes at the track easy and scientific too. I also noted that Carroll Smith (or was it one of the others) advocates the idea of going too far past the ideal to make sure it gets worse again to eliminate the subjectiveness. Of course that is assuming you have the money and time to do that much testing.

i agree, and i know i am in the same boat, that at this stage it is all about track time. Mine amounts to zero for several years now. at least you are out there.

cheers
michael
Ben Lipman
Goo Roo
SA
Soarer TT manual, plus TT track car, plus a spare shell

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Tuesday, July 15, 2014 - 11:02 pm, by:  Ben Lipman (Ben12a) Edit Post Delete Post Print Post   View Post/Check IP (Moderator/Admin Only) Move Post (Moderator/Admin Only)


Andrew McKellar wrote on Tuesday, July 15, 2014 - 05:09 am:

And if all that fails you could always just drive faster...



I don't need to be faster to make a giant leap forwards, just more consistent. In any one of those sessions when we were testing I should have run a 1:07 if I put 10 good corners together.

Since the last post I have had the car up on stands again. I zeroed all the springs and shocks and re set them to be exactly the same left to right. Every detail was measured, spring seat, preload (2mm) spring length captive, spring length loaded, spring perch and shock body length. When it was all put back together the ride height was a lot closer to dead level, with only 1mm discrepancy at the rear.

I then did an alignment, now running 4mm toe in at the rear to try taming the oversteer, and reducing front toe out to virtually nothing (0.6mm total). Camber, castor remain the same.

I

Michael McKellar wrote on Tuesday, July 15, 2014 - 09:07 pm:

Also make a note of how many turns of the adjusters result in how many mm of ride height



I did this for toe and ride height, at the front and rear. I haven't figured out the effect of lengthening or shortening the traction rod on handling, so haven't measured a 'turn' yet.

All I need to do now is adjust the ride height so it is level with me on board.

I am borrowing a set of corner weight scales soon, so will finally get an accurate weight for the car. I will also see what the corner weights are, and maybe be able to make some adjustments to get that even too.

Not exactly exciting work...could post pics of rulers, strings and callipers, but wont.
Ben Lipman
Goo Roo
SA
Soarer TT manual, plus TT track car, plus a spare shell

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Sunday, July 20, 2014 - 02:45 pm, by:  Ben Lipman (Ben12a) Edit Post Delete Post Print Post   View Post/Check IP (Moderator/Admin Only) Move Post (Moderator/Admin Only)

I have borrowed some corner weight scales. The table below is the current weight of the car with me and all my kit sitting in the drivers seat. (plus the control box). All weights are in Kg.

I also used the centre of gravity function to find both the horizontal CG(116cm rear of front wheels), lateral CG(94.1cm from left wheel edge) and vertical CG(54.8cm above the ground). This means the CG of the car is about my left knee when I am sitting in the seat.

Left FrontRight Front
Wheel weight + driver397443.5Wheel weight + driver
% of total2730.2% of total
Weight front + driver840.5
% front of total 57.2
Total Weight + driver1470
L-R cross weight705
R-L cross weight765.5
Weight rear + driver630
% rear of total 42.8
Left RearRight Rear
Wheel weight + driver322308Wheel weight + driver
% of total21.920.9% of total
Factory Kerb weight1560
Current weight1374
Weight loss186
% loss11.92
Target (85% Kerb)1326
Still to lose48


The table at the bottom shows the minimum Open class weight (15%of the factory kerb weight FOR THAT MODEL). Using the JZZ30 weight I can afford to lose another 48kg. Now to find it...
Paul Kalie
TryHard
NSW
TT

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Sunday, July 20, 2014 - 03:09 pm, by:  Paul Kalie (Ajzs) Edit Post Delete Post Print Post   View Post/Check IP (Moderator/Admin Only) Move Post (Moderator/Admin Only)

With or without full fuel cell ?
57.2 front Vs 42.8 front rear weight bias ?
Blake Gloyn
Goo Roo
manawatu
soarer JZZ30 TT

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Sunday, July 20, 2014 - 03:23 pm, by:  Blake Gloyn (Blakenz) Edit Post Delete Post Print Post   View Post/Check IP (Moderator/Admin Only) Move Post (Moderator/Admin Only)

that weight isn't bad given you are in the car(for a soarer at least!) You seem to have targeted the heavy bits already... oh 48 kgs, where are you?
Ben Lipman
Goo Roo
SA
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Sunday, July 20, 2014 - 03:56 pm, by:  Ben Lipman (Ben12a) Edit Post Delete Post Print Post   View Post/Check IP (Moderator/Admin Only) Move Post (Moderator/Admin Only)

Paul- yep, 57% of the weight is on the front wheels, 43%rear. This is with about a quarter of a tank plus a 10kg weight on top (simulates 1/2 a tank total weight)

The cross weights are pretty bad - with a 60kg difference. I am going to go out and try a few things to see if I can "add" 15 kg to the left front and right rear corners, simultaneously taking 15kg "off" the right front and left rear without destroying the ride heights too much.

Clearly the optimal solution is to find 48kg in the front right corner and bin it. Unfortunately I need the brakes, air filter, turbos, powersteering etc that are located in the front right quadrant of the car. I might save a couple of kilos if I make my own steering column, and Kurts intake piping (made in alloy) might also save a kilo or two. Another kilo might be hiding in a custom pedal box, after ditching the brake booster. There is a couple of grand there for those kilos.

The other option is to see if there is any weight savings in cutting the steel inner guards and radiator supports etc out and replacing them.

I am a bit disappointed with the total weight of 1374 kg. I really hoped it was much closer to 1300kg. Time to rip the cage out and remake using 2 inch thin wall exhaust pipe, LOL.
Blake Gloyn
Goo Roo
manawatu
soarer JZZ30 TT

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Sunday, July 20, 2014 - 06:57 pm, by:  Blake Gloyn (Blakenz) Edit Post Delete Post Print Post   View Post/Check IP (Moderator/Admin Only) Move Post (Moderator/Admin Only)

bin those cast turbo exhaust manifolds. reliability and strength are overrated:-) That right front door hinge is 7kg, also. Are you still running standard hinges?
Have you done corner weights with you sitting back 4 to 6 inches? some guys move the pedal box, and alter the steering column, and move the seat base back. Because that extra weight in front right is you.(35% of drivers weight transfers to the front right corner in a factory positioned Soarer seat)
Ben Lipman
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SA
Soarer TT manual, plus TT track car, plus a spare shell

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Sunday, July 20, 2014 - 07:29 pm, by:  Ben Lipman (Ben12a) Edit Post Delete Post Print Post   View Post/Check IP (Moderator/Admin Only) Move Post (Moderator/Admin Only)

Had a go at getting cross weight (wedge) even. I went 1 turn up on the left front spring perch (effectively increasing preload) and 1.5 turns up on the right rear. The reason for different adjustments on the shock is to actually make an equal adjustment at the wheel taking into account the motion ratios I worked out previously. See, not a wasted effort! This got the cross weights to 742/730 or 50.6/49.4%.

I could have left it there, but thought I would make a slight adjustment (1/8 of a turn up at the front left) and see if that was closer to 50/50. Very happy when I re-weighed it and came back with 736.5/736.5. I can't get it any better than that. The weights are below. Table looks much better on my laptop.

Left FrontFrontRight Front
413.0840.5427.5
57.1%
Cross Weight
736.5
Left50.0%Right
722.0751.0
49.0%Total51.0%
1473.0
Left RearBiteRearRight Rear
309.0-14.5632.5323.5
42.9%

I can't get under the car and measure the ride heights as I am carrying a torn up shoulder. In theory, because the springs were adjusted evenly on the diagonal there should be no ride height variation. There may be a tiny rise in the left front corner because of the second adjustment, but in my hack such a small variation should not be noticeable.
Ben Lipman
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Sunday, July 20, 2014 - 07:38 pm, by:  Ben Lipman (Ben12a) Edit Post Delete Post Print Post   View Post/Check IP (Moderator/Admin Only) Move Post (Moderator/Admin Only)

Blake- missed your post when I posted mine. Actually 43kg of my weight ends up on the right front corner. Only 3kg ends up on the left front.

Andrew wants to move the seat back 5-6 inches to the roll cage, but before I can do that I need a pedal box, steering column, and new seat mounts. The first pedal box I looked at costs $2995 (perusic engineering). I can't afford it. Maybe if something second hand pops up, but even then the kitty is dry due to the engine. This year is for driving, not building.
Andrew McKellar
DieHard
NSW
V8 Soarer Sports Sedan

Posts: 743
Reg: 06-2008

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Monday, July 21, 2014 - 12:01 pm, by:  Andrew McKellar (Toymax) Edit Post Delete Post Print Post   View Post/Check IP (Moderator/Admin Only) Move Post (Moderator/Admin Only)

Did you have the rear wheel weights arse-about in the first table? It made no sense to me that it would be lighter on the side of the car that you are sitting in.

Compare to mine (with driver):

LF = 346
RF = 392
LR = 316
RR = 351

Total = 1405kg

% Front = 52.5

The 70kg difference has got to be the engine - 1UZ = 170kg, 1/2JZ = 240kg.

I concur with Blake's comments, but see the $$$ in changing seat position. The door hinge is a cheap fix though - your doors weigh bugger-all now, so time to get on with designing a 2-stage gate hinge...

The front to rear % is big. Maybe adjust some of that rake out of it to assist with that?
Ben Lipman
Goo Roo
SA
Soarer TT manual, plus TT track car, plus a spare shell

Posts: 3784
Reg: 04-2006

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Monday, July 21, 2014 - 05:41 pm, by:  Ben Lipman (Ben12a) Edit Post Delete Post Print Post   View Post/Check IP (Moderator/Admin Only) Move Post (Moderator/Admin Only)


Andrew McKellar wrote on Monday, July 21, 2014 - 12:01 pm:

Did you have the rear wheel weights arse-about in the first table? It made no sense to me that it would be lighter on the side of the car that you are sitting in.




No. They were correct. I had to adjust the springs on that diagonal to get more weight onto the LF/RR, and get some weight off the other diagonal. The side to side weight doesn't change, neither does the front to rear, but you can change the percentage of it on the diagonal. The only way to change the front/rear or side/side weights is to physically move mass around the car itself. Don't worry, I was sceptical of the theory until I did it myself.

I'll send you the excel spread sheets that shows original, after 1 adjustment, and then after the final adjustment. Apart from the car inexplicably gaining 2.5kg from the first weigh in to the third, the front/rear remains constant as does the left/right percentage.

Basically I was driving a car setup like a three legged chair. Either the left front or right rear leg (wheel) was shorter than the other legs. This explains both the right rear coming off the ground/locking up in the 1/2 braking zone (right hand kink leading into right hander for those playing in other states) and the sensation of the car falling over onto the right rear tyre coming out of the fish hook.

I just calculated your cross weights based on your data. You have a RF/LR of 708kg (50.4%)and a LF/RR of 697kg(49.6%). A difference of 13 kg, meaning your car is pretty nicely balanced, but you could wind some spring into the LF/RR diagonal and make it even if it bothered you. You can also note that your right side of the car is 81kg heavier than the left (L662/47.1% versus R743/52.9%). Like me, you may benefit from moving any mass you can to the passenger side. Alas, like me, you have probably already picked all the low hanging fruit.

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