Stripped one down at lunch time, bit of heat on the spring perch to free it up, I got carried away and started to melt it Derr, that's alloy, Gary The threads will clean up with a wire brush, I'll shot blast the lower parts of the bodies and treat them to a lick of whatever. Inserts are fecked, rebound of the damper is like a pogo stick, *doing doing doing* no wonder it was a bit bouncy Someone stated in my widetrack thread, now i've added extra static camber, this will reduce the spring rate - I don't fully understand it to be honest.. anyone? I'm trying to find out the rate of the springs, I've mailed Dubsport who I bought the FKs from originally and FK themselves I'll be suprised if they release the spec TBH, if they don't, I hear a local race car prep firm Randall motorsport ( specialise in short oval stuff ) have a spring tester to check the rates, prolly worth a trip over there ( only about 5 miles or so ) so I can see where I need to be with the spring rates. On the FK supplied front springs they just have a code FK1866 The fronts are 180mm free length (7") and 60mm ID - Wonder if the last 6 of the code works out as a metric equivalent of lbs...?
the final digit of the number is the spring rate in N/mm x10 So 6 is 60N/mm Thats from the FK catalogue The reduction in spring rate is cos of the altered angle and/or the extra leverage i believe
Nice one Andy, there was a vague post on Vortex about the codes, sounds about right. So, how to convert 60N/mm into lbs???? Edited by: GVK
(N/mm x 5.709 =pounds/inch) So, 60N/mm = 342lbs Didn't think they would be as stiff as that. Edited by: GVK
Bloomin' Germans, 60mm ID coil over springs are about double the price of the popular 2.25" 'spose the top adjustable damper needs a wider body to fit all the gubbins inside..
G- I cant imagine they are really 342Lb springs tho surely? thats really pretty hard for a road car ,I'd whip a rear off & nip to the spring measuing place, be good to know for sure what the front & rear rates are & you have to know the exact rate if you are consdiering getting some harder ones made up. Edited by: iguana
Yep,that's what I'll probably do. I found the claimed rates for FKs BMW 3 series coil overs and they were 420 f 400r .. If I undertand correctly though, if they're a 342, by pushing out the hub/ball joint 'wide track' blah de blah, it reduces the spring rate.
Backs up the metric conversion.. "H&R also carries a complete line of 60mm I.D. main and tender springs. Main springs range from 100 mm to 300 mm in length and 30 N to 700 N (N/mm x 5.709 =pounds/inch) in spring rate. Tender springs vary in length from 40 mm to 130 mm, with numerous spring rates available." DT catalogue list KW springs in 60mmID for 35 + vat each - bet they're not a stock item, though.
Never tried it, but might be able to buy top and bottom collars to convert over to 2.25". A pair of 2.25" springs is ~ 55. Saving half may get you a good way towards the new collars. Difference in diameter is 2.85mm...BTW
I'll see if a 2.25" spring will fit over the shock body, they seem quite a bit larger diameter than the other coil overs I've seen.
Hate to mention "Avo" and me in the same sentance...but. They had everything i needed in stock when i had them revalved. they also had the main tubes, spare collars and grub screws and a full rebuild was turned around inside a week DELIVERD there and back !! Great service - pooe shocks.
Avo have a good range of springs in both sizes Try faulkner race springs - see keiths mk1 suspension thread - i'm sure they do the full range from stock. Avo spring rates where 9" fr @250lbs 10" rr @200lbs They for some reason recommend uping the front to 300 for track. 340+ Sounds a bit "odd" for road rates
They (faulkners) do 2.25s from stock, but other diameters are special order B. 340 does seem odd, but that's what the code works them out to be. If I get chance and they're still open at lunch tomorrow, i'll go to Randalls and get them tested. Edited by: GVK
ahh bum - cant really remember but that time at stealth when i stole your car, did i comment on the suspension ?
The spring rate would effectively be reduced as the strut body is now at a greater angle with respect to vertical. To make this clearer, if the strut was absolutely vertical, any movement of the car body up/down will equate to exactly the same movement in the top of the spring in the vertical dimension. Now say the strut is at 45, for every inch the body moves down, the spring only compresses by 0.7 inches so the poundage is effectively reduced. This really all applies to kit cars etc. where you have those small coilovers at 45 so it makes a big difference. On yours gary the difference will be bugger all so in short, forget about it. Hope this is what you meant/were talking about, if not, ignore my ramblings Joe
Joe, boss said the same thing, when they built short oval cars, with the shocks mounted at, as you say a 45 deg angle, it required springs up to twice the rate to make them work. He said, for the amount of angle I'm adding to it the difference will be minimal. Had chance to nip down to Randall motorsport and have the FK front springs tested - 225 lbs force required to compress them 1" So, WTF does that 6 mean on the code ? Also on my travels dropped into short oval racer Dick Hillard's place, he's lent me a 2.25" and a 2.5" spring to see if they'll fit over the bodies, which they do, but the top hat and adjusting collar,...... don't. Stripped the other coil over down today, the damper in the OSF was double fecked Shot blasted the lower part of the casings and etch primed them, will get the lads to blow some colour on them this week. collection of springs, fat little dumpy one on the left 700 lbs Shot blasted / etch primed coil over body Bonrath poly top mount, supplied nuts won't fit the Koni damper, so having to source some M14x1.5 'half nuts' to do the job. Edited by: GVK
