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Rear suspension height?

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SuperOwen Fahrvergnugen

868 posts · joined Jan 2009 ·

#878278
I just did my first track day at wakefield today and had a blast, so I think I might make the car a bit more track orientated. The car will still be driven to and from the track though as I dont have a trailer.
I dont want to change too much on the car yet as it's the driver that needs work but was considering lowering the back a bit before the next outing.
The car didn't handle too badly but the rear end felt a bit loose, hard to describe as I dont have much seat time yet.

Current setup is as follows
1971 1302
Topline Maxx Struts set at their highest setting (pretty low still)
bugpack heavier front sway bar 7/8
empi rear bar 3/4
stock torsions rear, stockish height. kyb shocks
16x6 and 16x7 wheels, 195/50 front 225/55 rear, waiting for rears to wear out to put a 205 on.

The car does have a bit of rake to it at the moment, mainly to make life easier when it was my everyday car. I was thinking either leave everything alone and just lower ther rear or put some heavier torsions in and remove the rear sway bar? Obviously I prefer the lowering option as its free!! It did understeer on the street before I put the rear bar on to match the front.

The pic below gives an idea of the current height, it's fairly raked, probably more than the pic suggests.

Any ideas??

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hellbugged 48's and straight cuts

5,080 posts · joined Apr 2003 ·

#878284
Yes rake sucks on corners!

matberry Moderator Go hard or go home

8,114 posts · joined Mar 2006 ·

#878308
By all means lower the rear a tad, but why not put a set of torsion bars in too. Even type 3 torsions will be an improvement, then a bigger rear sway bar.....
Matt Berry Motorsports...air cooled advice, repairs and mods Ph 0408 704 662
OFF-ROAD,CIRCUIT,DRAG,STREET,ENDURANCE

SuperOwen Fahrvergnugen

868 posts · joined Jan 2009 ·

#878313
I already have a 3/4 inch rear sway bar. Just not sure heavier torsions are necessary.

mactaylor Custom Title Time!

1,005 posts · joined Aug 2007 ·

#878322
heavier rear torsion bars will help lessen understeer. tyre pressure is very important aswell. have a read of ct or jaks posts to see what they have done they both love a punt and ct has tyre know how!
EVERLAST CONCRETE TANKS
1800 552 123

matberry Moderator Go hard or go home

8,114 posts · joined Mar 2006 ·

#878337
SuperOwen wrote:I already have a 3/4 inch rear sway bar. Just not sure heavier torsions are necessary.
yes I read that, bigger rear bars and better/bigger rear sway bar would be my recommendation, unless you have some MAJOR weight reduction plans.
Matt Berry Motorsports...air cooled advice, repairs and mods Ph 0408 704 662
OFF-ROAD,CIRCUIT,DRAG,STREET,ENDURANCE

SuperOwen Fahrvergnugen

868 posts · joined Jan 2009 ·

#878349
No worries, ill keep my eyes out for some wagon torsions.

colin Fahrvergnugen

984 posts · joined Mar 2007 ·

#878546
Aussie Dubbin wrote:Find some thIcker bars out of a type 3 then as you lower it all stays flat. Sounds like great fun. Inch lOwer at the rear is what I keep hearing
Sorry Aussie, but Owen, do not lower the rear below the front height you will induce massive understeer.
For starters you are running to larger tyre ie 225 on a 7 inch rim. Max for 7 inch rim for racing is a 205. The tyre would be walking around on the rim giving you the feeling of a loose rear end.
What tyre pressure were you running and what tyres.

Cheers Col

SuperOwen Fahrvergnugen

868 posts · joined Jan 2009 ·

#878566
The only reason I have a 225 is because that's what came on the porsche boxster wheels, factory fitment I think. The plan was always to replace it with something more appropriate, but figured I would wear them out a bit first, ill be looking at street/track tyres soon but not yet.
I do run low tyre pressure, 18psi front and dropped the rear a few psi to 22psi, which actually seemed to settle the car?
Just in case anyone had the wrong impression the car is currently NOT setup for any racing, I just drove the car to the track and ran some laps to see if I liked circuit stuff. I would now like to make small and affordable changes to improve the fun factor and hopefully go quicker as my driving improves. Car has to remain able to drive from sydney to wakefield and the occasional daily driver duty.
Thanks for all the suggestions so far, can anyone recommend a good handling theory book? Ilike to know how stuff works when making changes.

bigrudi Wolfsburg Wizard

401 posts · joined Apr 2005 ·

#878575
gday owen dont go maad changing things yet thre supposed to go side ways when u push them its called driving .dont go any thicker on the rear bar put it on the softest seting,put some more track time in first and try changing tyre pressures to get the balance right presures seam very low ,when u wear ur tyres out get a set of r spec tyres or federal performance the differance will be increadable,then when ur at that stage start stiffening ur suspension cheers Rudi

colin Fahrvergnugen

984 posts · joined Mar 2007 ·

#878610
bigrudi wrote:gday owen dont go maad changing things yet thre supposed to go side ways when u push them its called driving .dont go any thicker on the rear bar put it on the softest seting,put some more track time in first and try changing tyre pressures to get the balance right presures seam very low ,when u wear ur tyres out get a set of r spec tyres or federal performance the differance will be increadable,then when ur at that stage start stiffening ur suspension cheers Rudi
100% spot on Rudi, your tyre pressures are way to low, for a street tyre.
With pressures that low the car will be soggy and floating around corners with the front tyre trying to roll off the rim and the rear breaking out from underneath you.
Front tyre pressure cold start at 30psi then after a few laps come in and check, rear start with 34psi cold.
After getting some heat in them adjust up and down until you feel okay. This may take lots of laps and maybe a few track days to work out.
As far as the rear sway bar is concerned, slow tight tracks = stiff rear bar. Fast open tracks ie Wakefield Park = soft rear bar.
Forget books, learn youself from your own experiences, picking up little pieces of info from others and have fun.

Cheers Col

SuperOwen Fahrvergnugen

868 posts · joined Jan 2009 ·

#878612
Sounds like a good plan plan Rudi, I'll bump the tyre pressures up before I run it next on the 12th jan. I've got time so I'll drop the rear a little as well and then leave it alone for a while. Looks like I've found a set of 40mm throttle bodies as well so I might throw together a cheap motor with a bit more poke to play with, the motor in it is essentially stock, dont need a lot more power for now but a a bit more would make things a lot more fun.