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Rear Suspension

Started by _BULEBOSS_ , Dec 09 2011 08:43 AM

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54 replies to this topic

#1 _BULEBOSS_

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Posted 09 December 2011 - 08:43 AM

I am new to the forum and I am sure this would have been covered before.
A few questions.

What works better?
Rear springs softer or harder ?
Shocks softer or harder ?

Is it worth boxing the lower control arms ?

Cheers and Thanks

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#2 wot179

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Posted 09 December 2011 - 08:57 AM

Welcome to the forum.

There are a few guys on here that go fast,take their advice as they have been there and done that.

Uncle festa and Mumbo are a couple that spring to mind,as Im guessing this is for a dragrace application

What I would try first,
RHR spring harder
50-50 shocks in the rear
soft springs(6cyl) and 90-10s in the front
Flick the swaybar
Yes,box the control arms.
Im happy to be corrected,cheers,Craig.

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#3 dattoman

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Posted 09 December 2011 - 10:00 AM

Removing one of the top arms seemed to be an old trick too one
Made the car squat alot harder on the launch

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#4 _CHOPPER_

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Posted 09 December 2011 - 09:16 PM

Box the arms or spend about $600 on new tubular adjustable ones.

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#5 _OLC383_

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Posted 13 December 2011 - 08:45 PM

_{Yes box the arms, also get some double adjustable rear shocks QA1 (11-1517) from McDonald Bros $415 each (when i got mine back in June) & they will bolt straight in to any early Holden, then you'll have all the adjustment you need, insted of swopping different rate shocks to find the right ones, also if you can adjustable upper control arms (11-1170) also from McDonald Bros $315 the set.}
_{Flick the sway bar if you are drag racing , it made no difference to mine, if you have serious horse power get a rear torsion bar set up, they are more adjustable & are alot better for drag racing.}
_{just my thoughts, hope it helps}
_Wayne

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#6 _injlc304_

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Posted 14 December 2011 - 04:34 PM

when you guys say flick the sway bar do you mean front or rear?

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#7 dattoman

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Posted 14 December 2011 - 07:13 PM

rear

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#8 Hell34

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Posted 14 December 2011 - 07:56 PM

when you guys say flick the sway bar do you mean front or rear?

Remove both front and rear less drag on all the bushes will let the front end lift faster for more weight transfer to the rear tyres plus the weight loss from removing them every little bit helps in the end .

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#9 warrenm

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Posted 15 December 2011 - 07:56 AM

_{Yes box the arms, also get some double adjustable rear shocks QA1 (11-1517) from McDonald Bros $415 each (when i got mine back in June) & they will bolt straight in to any early Holden, then you'll have all the adjustment you need, insted of swopping different rate shocks to find the right ones, also if you can adjustable upper control arms (11-1170) also from McDonald Bros $315 the set.}
_{Flick the sway bar if you are drag racing , it made no difference to mine, if you have serious horse power get a rear torsion bar set up, they are more adjustable & are alot better for drag racing.}
_{just my thoughts, hope it helps}
_Wayne

Are those QA1 part # or McDonald Bros?

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#10 _injlc304_

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Posted 15 December 2011 - 04:34 PM

Remove both front and rear less drag on all the bushes will let the front end lift faster for more weight transfer to the rear tyres plus the weight loss from removing them every little bit helps in the end .

doest the rear sway bar stop diff roll and side movement and make both springs compress at the same time? wouldnt this be to an advantage?

i have no idea... so im not being a smart ass...just putting it out their

Edited by injlc304, 15 December 2011 - 04:39 PM.

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#11 _BULEBOSS_

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Posted 15 December 2011 - 05:02 PM

I thought a rear bar was a good Idea

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#12 _OLC383_

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Posted 15 December 2011 - 06:55 PM

Hey Warrenm,

Thats the part number that McDonald Bros used, got a mate currently over in the USA who just recently brought the same shocks over there part # was QA1 TD-501 hope that helps,

Remove the rear sway bar it made no inprovements on my launches at all

Wayne

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#13 EunUCh

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Posted 15 December 2011 - 10:19 PM

I have never been involved in drag racing in any way shape or form but from my limited research i would suggest that
you look into squat/anti squat and centre of gravity points on the car u r modifying,basically the 4 bar rear susp.is pretty good.
If u can imagine or somehow put on paper the 4 bar system and draw lines through rear uppr/lwr arms and make the lines from the centre
of the bushes of both upper & lwr arms u will find that they intersect somwhere towards the front of the car.ideally those lines will
intersect at the COG of car.this is good,,,buut, when u plant it and the front lifts up under torque where those lines meet(called the instant centre)
it all changes,,and this causes problems,not only does ur inst.cntr change but the whole car is now being twisted as well.some info on this is
on page 145 onwards..book is Modifying Your Holden..probly heaps more on i/net.

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#14 _injlc304_

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Posted 16 December 2011 - 09:20 AM

Search a user called toryoda (Craig). He has helped me heaps with my suspension. I haven't finished it yet but he is really helpful and explains it all well and on a tight budget.

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#15 _nos 598_

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Posted 22 December 2011 - 06:39 PM

a rear sway bar ,bolt on is beneficial. Wayne torsion bar is better but if you are going to be doing true street style racing at apsa events they are not allowed.

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#16 _OLC383_

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Posted 22 December 2011 - 06:59 PM

BUGGER, bloody rules, problem is, i dont think the 9" tyres will like it without the torsion bar, arewell looks like we stay in DYO, (for now), blower not going on until after winters, Kays doing to good in the points to pull the car off the road now.

Thanks Col

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#17 _nos 598_

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Posted 30 December 2011 - 02:09 PM

<p>

a pic of our car with a rear bar, leaves pretty flat. Posted Image

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#18 _injlc304_

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Posted 02 January 2012 - 12:14 PM

What rear springs are you lot running? I've got 4cyl LC springs in ATM but it sits too low. Will it make much difference if I put 6cyl springs in the rear?

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#19 _CHOPPER_

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Posted 02 January 2012 - 12:24 PM

Rear spring rates are very similar, as most of the extra weight is between the front wheels.

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#20 _injlc304_

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Posted 02 January 2012 - 01:23 PM

Oh ok. I've just gone from Lovell sports low all round to 6cyl front n 4 cyl rear but she scrubs hard all round now n my exhaust it almost on the ground

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#21 warrenm

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Posted 08 January 2012 - 10:35 AM

Oh ok. I've just gone from Lovell sports low all round to 6cyl front n 4 cyl rear but she scrubs hard all round now n my exhaust it almost on the ground

Fit some spacers on top/underneath the springs to lift the car to the required height.