greenwood03
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| posted on 15/8/11 at 01:27 PM |
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Rear Spring ' poundage' - spring rate??
OK this is a bit of a generic post - basically looking for 2 things please.
a/ some guidance as to what others are using spring wise on their 7esque cars ( rate + length ).
b/ a bit of sanity checking of my likely flawed logic.
So, i had a Tiger Cat which i think is overly sprung. As standard they come with 9inch springs of 300lb. Many have gone further to 350lb to alleviate
bottoming out when there's a hefty passenger in teh co-pilot seat. The resultant ride (imho ) is a tad harsh, brilliant on a smooth road/track,
but difficult to drive swiftly over a bumpy surface as the rear of teh car isnt in contact with teh black stuff.
My simplistic thoughts were, instead of raising the poundage, wouldnt it be more effective to lower the poundage and lengthen the spring, ie/ 275 and
10 inch. The extra length could soak up part of teh driver/passenger + car weight and hopefully give enough travel for the springs to work
effectively.
i've tried both 300 + 350's in the 9 inch. the 350lbs make the car very very firm, the 300's feel better and soak up more of the
bumps, but i still think there's room to soften it a little further, although i imagine that that in turn may mean changing teh front springs so
that they aren't out of whack with teh rears?
anyway, as a starying point grateful if a few folks can post up what they're using and from that may get a bit of a feel for what i could trial
on mine.
cheers
Mark
http://southernkitcars.comIntermarque Club for owners in the South/South East
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myke pocock
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| posted on 15/8/11 at 02:54 PM |
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Well, I originally built mine with ex Lotus 7 coil over units front and back. One was leaking so I bought replacement Gaz units for that king of car
and the back springs are rated at 190 lbs ( cant remember what the fronts are). I have been told that they may be a bit soft but with the adjusters
backed right off it only bottoms out at the back very, very occasionally and rides nicely. As you say, heavier poundage is OK for billiard smooth
roads but life aint like that, certainly not in Cumbria anyway!!!
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Mal
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| posted on 15/8/11 at 03:15 PM |
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If it helps, commonly used spring rates on a Westfield with IRS is 275 lb/in( 7" free length) on the front and 180 lb/in (9" free length)
on the rear.
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greenwood03
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| posted on 15/8/11 at 03:48 PM |
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thx guys.....anymore care to shed light on what they're using ???
http://southernkitcars.comIntermarque Club for owners in the South/South East
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pewe
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| posted on 15/8/11 at 05:01 PM |
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Matt at Procomp on here is always very helpful.
If yours is a live axle set-up it requires different poundage springs and specific valving in the shocks due to higher unsprung weight.
Mine is a live axle with 150lb springs and Matt supplied the Protech shocks suitably re-valved.
Suggest you sort it out prior to the Northern trip as some of the roads are pretty undulating!
HTH.
Cheers, Pewe 
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GeoffT
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| posted on 15/8/11 at 05:07 PM |
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My car is a 'book' live axle Locost - originally had 150lb rears (8" ) but I found I needed the shocks a bit harder than was
comfortable to prevent bottoming, so just recently upped them to 200lb and backed off the shock settings. This gives a nice compliant ride with no
bottoming out.
I also felt that on a recent trackday the rear end breakaway was a bit more progressive, it would snap out very suddenly with the previous
setup......faster than my grey haired reactions could keep up with most times....
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macc man
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| posted on 15/8/11 at 05:56 PM |
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An alternative to high spring rates is to fit a rear anti roll bar. This will stiffen up the handling in the corners and allow lower spring rates.
Just a thought.
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Surrey Dave
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| posted on 15/8/11 at 07:08 PM |
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140 lbs
Originally fitted 140lbs ride was good but not enough travel in the damper, so they bottom out , so I fitted 225lbs to limit travel.
Ideally it would be nice to re do the mounts to fit a longer damper or the other option is to angle the damper to give more travel from the shorter
damper.
Jon Ison angled his in towards the centre of the car.
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franky
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| posted on 15/8/11 at 07:24 PM |
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quote:
Originally posted by macc man
An alternative to high spring rates is to fit a rear anti roll bar. This will stiffen up the handling in the corners and allow lower spring rates.
Just a thought.
My understanding is that if you've got the right spring rates/dampening there's no real need for an ARB.
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Marcus
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| posted on 15/8/11 at 08:13 PM |
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I use 150lb 9" on the back of my live axle Locost with Gaz shocks. Don't think I've bottomed out yet, but may change them next year
when I hope to go hillclimbing 
Marcus
Because kits are for girls!!
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