Johneturbo
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| posted on 22/7/08 at 05:55 PM |
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correct suspension setup!?
I've done a fair few miles with the car now, and i know it might take a while for it to settle, but i feel like the front of the car just skips
over bumps at any decent speed on B roads (ie 60mph)
no matter what i try with the adjustment on the front shocks its the same.
the car has been fully laser tracked with 0 front toe to make it a bit more bearable and 1.5 neg front camber, as in the set up instructions.
i've tried different tyre pressures, i'm now on 15psi all round.
i'm at a loss really with what to try and knowing if this is normal, i've driven cars with hard suspension before, but it feels like there
is no give at the front at all.
there is no delfection at the front if i push down on the front of the chassis, is this a trait of inboard suspension?
any advice would be great 
[Edited on 25/7/08 by Johneturbo]
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coozer
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| posted on 22/7/08 at 05:57 PM |
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Have the shocks got plenty travel left or are they riding on the bump stops?
1972 V8 Jago
1980 Z750
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CRAIGR
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| posted on 22/7/08 at 05:58 PM |
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What poundage springs are they John????
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mr henderson
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| posted on 22/7/08 at 05:59 PM |
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Sounds like the springs are far too stiff (as they frequently are in LSIS's)
Do you know what the spring rate is?
John
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TimC
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| posted on 22/7/08 at 06:11 PM |
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I had the same thought on spring rates as Mr H. In comparison, mine deflects relatively well in the static position. Is it possible that you have
CEC-spec springs rather than BEC-spec?
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miikae
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| posted on 22/7/08 at 06:13 PM |
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On my RH S7 i have inboard Gaz shocks and 130 lb springs and tie bars , (ARB thrown away ), suspension works great now , sounds to me that your
springs are far too stiff , what poundage are they ?
Mike
If it can be done it i will be done .
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mookaloid
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| posted on 22/7/08 at 06:21 PM |
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As above - springs too stiff
"That thing you're thinking - it wont be that."
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worX
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| posted on 22/7/08 at 06:26 PM |
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Hi John'
What ride height are you running front and rear?
What's the poundage of the springs front and rear?
What setting do you have the shock absorbers on, all round?
What uprights do you have on the front?
Steve.
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Mark Allanson
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| posted on 22/7/08 at 06:31 PM |
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Static zero toe will give you toe out when in motion - problem solved!
I have 30' static toe in and the ride is superb
If you can keep you head, whilst all others around you are losing theirs, you are not fully aware of the situation
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Paul (Notts)
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| posted on 22/7/08 at 06:33 PM |
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First thing I would check in this situation is whether the front wishbones move freely on the bushes.
Disconect the shock with the front end jacked up ( wheel removed ) and check the wishbones are free to move.
Had the same problem at first with my Viento. Turned out to be a problem with the bushes and crush tubes.
Paul
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Davey D
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| posted on 22/7/08 at 06:41 PM |
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i noticed that it is quite hard on mine, but never thought anything of it, as i havent seen anyone else bring it up until now, and i also havent yet
driven the car to know how it rides.
mine is so hard that if i remove the nose cone, and stand on the frame at the front, and jump up and down, the suspension barely moves 
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Johneturbo
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| posted on 22/7/08 at 06:44 PM |
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Ok guys first of thanks for the replys, it's nice to know help is out there
i've taken a few pics and i'll try ans answer the Qs
the front springs are 175
i've tried all the settings on the shocks to no effect really.
front uprights are mnr cortina type.
ride hight is front 150mm
rear about 165mm
i can't get the front much lower as the springs are near the platforms and the pushrods are fully wound in
if i jack the car up the suspesion does droop down, but i will check the bushes as another thing to try.
here's some pics as it sits
 
Rescued attachment 22072008463.jpg
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Johneturbo
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| posted on 22/7/08 at 06:45 PM |
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.
 
Rescued attachment 22072008464.jpg
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Johneturbo
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| posted on 22/7/08 at 06:45 PM |
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.
 
Rescued attachment 22072008466.jpg
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Paul (Notts)
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| posted on 22/7/08 at 07:03 PM |
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You should be able to bounce the front end up and down. I can do mine even with 300lb springs on the front and back!
Paul
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mr henderson
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| posted on 22/7/08 at 07:08 PM |
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quote:
Originally posted by Mark Allanson
Static zero toe will give you toe out when in motion - problem solved!
I have 30' static toe in and the ride is superb
Are you serious, tune the ride by adjusting the toe?
John
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MikeR
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| posted on 22/7/08 at 07:20 PM |
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i've got 220 (or is it 240lbs) springs with a crossflow engine, when i stand on the chassis and bounce i can watch the wheels angle inwards and
the car body drops (made me smile the first time i saw it).
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Paul (Notts)
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| posted on 22/7/08 at 07:27 PM |
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Dont know anything about inboard suspension set up so ignore my thoughts ...
Something must be too tight to move you would be able to move the front end.
+ seems a big difference in moment of A compared to B - I would have expected it to be the other way round...
As I said ignore my thoughts as I dont have an MNR or inboard suspension set up
Paul
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mr henderson
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| posted on 22/7/08 at 07:30 PM |
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As Paul points out, the force required to move your wheels up and down is much higher than the 175lbs required for an inchof movement at the
springs.
Obviously you need to check for something making the suspension reluctant to move, but if no fault is found then you are off to the spring shop
John
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mark chandler
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| posted on 22/7/08 at 07:40 PM |
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That triangle changing direction of the movement must be gearing you shock up 3:1 maybe more as its past right angles so the amount of energy to move
increases even more, your 175lb springs are effectively 525lb. Thats your problem!
So you need less manly springs, and in the ideal world try and shorten the rod from the wishbone up to this to stop it going over centre.
Here's a crude drwaing hopefully showing what I am on about
[Edited on 22/7/08 by mark chandler]
 
Rescued attachment drawing1.jpg
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mikeb
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| posted on 22/7/08 at 07:46 PM |
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heh lots of advice,
I concur with the last post.
Using a bell crank for the inboard shocks will give you a rising rate shown by the ratio increasing with suspension movement in the last diagram.
If you have the spring and damper rates as for an outboard setup you'll be way to stiff might want to check what you asked for when you ordered
your coilovers. you should be able to bounce on the front and get some movement.
Just a note why does everyone stiff refer to spring stiffness in pounds? I though we'd been metric for a few decades now (Nm) but saying that my
springs came with force in pounds.
[Edited on 22/7/08 by mikeb]
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Johneturbo
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| posted on 22/7/08 at 08:18 PM |
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Paul/Mark
i did wonder about the angle of the rocker, thats why i posted a pic of it.
my problem is the pushrod is as short as possible and my lower wishbone is still a nats wisker below horizontal.
so i've had to drop the springs down to get it as close as possible, but then that's made the rockers sit a lot lower than ideal i
guess!?.
maybe a solution would be shorter pushrods?
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stuart_g
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| posted on 22/7/08 at 08:24 PM |
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My suspension is exactly the same as yours John and I have the same problem.
I was told to set the car up slightly different to the geometry in the build manual.
-1 to 1.5 degree camber all round.
1mm toe in all round.
This will not make any difference to the suspension not moving though. It does seem very hard.
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Andy W
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| posted on 22/7/08 at 08:34 PM |
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which way round is the bottom wishbone, is the push rod mounted on the top or bottom of the bone? this will alter the angle of the rocker
Andy
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David Jenkins
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| posted on 22/7/08 at 08:39 PM |
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I'm with Paul (Notts) - that poundage, with that ratio, would make for a huge spring rate. My conventional (external) coil-over setup uses
180lb springs, and I consider them to be as stiff as I'd want - no more.
If that does work out to over 500lb spring rate then it's WAY too high!
Perhaps you should talk to MNR as other people say that they're happy with this setup, which suggests that something's amiss with yours.
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