Reply With Quotewell that's 143lb/in so I've doubled them.... maybeOriginally Posted by sambb
Volkswagenist
Stock rear spring rate is 25 N/mm which google will convert to lb/in for you. To work out the number of free coulsvi normally look at them fitted to the car. You can see where the coil first peels away from the coil bound/captive ones. Mark that with a marker and then count how many complete coils +?whatever fractions of coils until the free coils bind again near the spring seat. You can get a fair idea of that off the car though so don't stress too much over that. You can often see where the seated parts of the springs bind up as there will be witness marks on them where they rub against each other. All the above gets very muddy trying to work out springs that are progressive or designed to be coil bound at rest like the H and R's.
Volkswagen Enthusiast
well that's 143lb/in so I've doubled them.... maybe
Volkswagenist
If you are still running that beast of a rear bar it might be enough.
Volkswagen Enthusiast
lol, yep, still there... rethinking having a similar thing on the mini though
Volkswagenist
Which springs did you end up with in the front, the stockers?
Volkswagen Enthusiast
yeah, I had a dig around last night for something the same length but a bit stiffer, but I don't really know what I'm looking for...
Volkswagenist
the fronts are 25 N/mm too, so 143lb/in, x 0.9 motion ratio and 0.9 again for leverage ratio (gary) and you are looking at 115lb/in at the wheel. The rears will be 143 x 0.8 x 0.8 = only 91lb/in due to different linkage ratio in the rear beam. By having 7kg front and 8kg rears my spring balance at the WHEEL ends up being square all round (based on those same calcs) , not inc bars. From what I remember Gary had suggested 7kg fronts as a starting point for me given how rough our tracks are etc and considering also that I was on 15in/205 mediums and after a track focussed setup. It could be that the tyres you intend to run would never develop the lateral G's to make running anything that stiff worth it. But on the flip side Gary also said that the spring rates you have in there now (same as what I'd had previously) were barely sporty street rates. The problem with the rear beam is that it is just so uncomfortable with stiff springs in there. You can remove the rear anti roll bar for the street to help make it tolerable and then beef it up for when you attack a track as a compromise but then you are left with an understeerer on the street.
Overall I think achieving that square balance in the wheel rate spring rates is a god starting point, but whether that model can work with soft spring rates the way its worked with my stiffer rates (340lb/in ish square at the wheel) I don't know,
Volkswagenist
I can send down my front weitecs 27N/mm and 8-10mm lower riding than the OE ones so roll centre still in a good spot. They measured only slightly stiffer than stock (in a press) but did feel a tad stiffer.
So with my rears, I went from 143 lb/in to 450 lb/in from memory which is about 3 times. I can tell you it is freaking hard, like stupidly rough on some roads. I bought the kids some icecream the other day and the poor things ended up with more on their faces than in their mouths the way the car jiggles around in the back. I dont know what your threshold for pain is but its barely streetable. You could aim to come back from that with say 7kg rears and then set the fronts up relative to what you can tolerate at the back. But having said tha, following what Gary has suggested I've definitely learnt that it is all in the back when it comes to going fast in a FWD. The transformation when you play with rear damper rates (that was worth 2 seconds to me at the dub nats), rear bar and proper spring rates is insane. You could even run the real stiff springs at the track and then the H and R's for the street because finding a happy comfort medium sort of compromises both if you know what I mean. Its a bit one or the other with the rear beam.
Dub Crazy
VWwA Super Moderator
I like the ride of my MCA coilovers, fronts are 10kg and the rears are 8. I do have some 6s for the back. For "comfort" but tbh, they arent that much more comfy and I'm too lazy to swap them in and out.
I added 50 series tyres to soften it up a bit though.
Volkswagenist
yeah I found the same Gav. I had some 6kg rears to use for the road. They didnt handle as well as the 8's with 7kg fronts but the discomfort was nearly the same. Thats why I think with the rear beam you either need to go focussed or comfort and its hard to find an area in between that will do both. Same as you gav I changed to 195/55/15's on the street to take the edge off Sydney potholes.
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