choosing spring rates

Welcome to the Mercedes 190 forum

Welcome to the Mercedes 190 owners forum, the place to be for all owners and lovers of the Mercedes 190E, 190 and 190D cars. Including Cosworth (2.3 16v and 2.5 16v), EVO 1 and EVO 2 models. Modified and concourse, track cars and daily drivers, all are welcome.

This free UK based club was started back in November 2005 to serve the w201 community and now has over 4000 members from all around the world and 340,000 + posts.

The members welcome you and encourage you to stay a while and have a look around. We offer you friendly chat and access to some very useful information as well as tutorials with photos and videos for many common repair and maintenance jobs. Whatever your needs there is a good chance you will be able to find what your looking for. Such as our Mercedes 190 buyers guide

Sign up to gain access to all areas including for sale / classified areas and country wide meetings and events. Many forum features and sections are only available once you sign up.

Join our us at mercedes190.co.uk!

If you're already a member please log in to your account:

choosing spring rates
Topic Started: Mon Jun 8, 2009 9:29 pm (335 Views)
dave_irl	Mon Jun 8, 2009 9:29 pm Post #1
I love offset. Posts: 8,729 Group: Admin Member #6 Joined: November 2, 2005	Okay, In my journey of car tuning/modification I have learned that springs should be purchased with spring rates in mind, not just ride height drop, which is a limited view. When I bought my H&R -60 springs who knows how many months years ago, I was mainly concerned with getting the car on the deck and I naively assumed they would be "hard enough". If course this is a long learning journey (90% the hard way..) and It now turns out with their soft rates of 70 & 75N/mm f&r that they are too soft altogether for my car, causing axle tramp on the rear and ALOT of bottoming out on the front. Even though I have mated them to special ultrashort (for beyond 50mm lowering) Spax dampers, these two problems are wrecking my head, especially on the front end. When I first dropped the car, I thought all was peachy, but it turns out the car was riding on the front bumpstops all along, it felt lovely and stiff for weeks until the left one eventually cracked and was pushed down around the damper body. The car lost another 10mm ride height but also gained alot more suspension travel, causing the 9J to at long last meet the arch. When I discovered this I removed the stop on the drivers side to equalise, and then both wheels rubbed like crazy. I since swapped to the steelies on the front but it has now become very clear that the springs are far too soft for these short stroke dampers as most bumps in the road are causing bottoming out and the damper body is knocking against my monster top mounts. It also caused a spectacular self flaring arch incident on saturday when I was out drifting in the rain.. On a nice long left hand bend, with plenty of oppo-lock, there was a nasty crunch: 185/65 & his friend -80mm ride height said a big f*** you to the arch and pulled it wayy out That arch was starting to rust anyway but hey... Luckily I had my estimate at the body shop today. Annyway I would like to discuss spring rates so I can order some new springs from Faulkners.. Mikael has some mega high rates in his proper H&R Nordschleife kit, Quote: Spring rate is 220nm/mm rear and 320nm/mm front = super stiff... and the Gorilla has some fairly stiff coils in his E30 too. Bearing in mind the slightly lighter 8V, I need to find the best rate for my car. For now I'm thinking of doubling it at least, or even matching Johans rates, as I would easily live with harder springs if my car handles better. I wouldnt feel great taking it on track as it is.. Should I be weighing each corner of the car or is there a good rule of thumb to go by?



Richy190E	Mon Jun 8, 2009 9:31 pm Post #2
Sales Rep Posts: 1,822 Group: Members Member #1,387 Joined: June 9, 2007	hasnt the nordschleife kit got like 3 free coils or something mad?



dave_irl	Mon Jun 8, 2009 9:36 pm Post #3
I love offset. Posts: 8,729 Group: Admin Member #6 Joined: November 2, 2005	Almost: Had I known about it at the time I would have saved for it, but I think if I can sort out my spring problem I will still have a very respectable set up, as the PSX tubes are adjustable and seem to be doing a good job, despite the soft H&Rs.. At least Faulkners springs are cheap. And the the nice lady at H&R emailed me back with the dimensions of my springs so I dont have to take them out to measure them!



matsalleh76	Tue Jun 9, 2009 2:14 am Post #4
Matsalleh76 Posts: 140 Group: Members Member #447 Joined: August 9, 2006	Springs and sway bars are an interesting and often frustrating subject. I have been through various iterations and have the car fairly well tuned to my style but it is still not "there". I like a neutral handling car with very little understeer, just on the verge of oversteer, quick turn-in, and little bump steer. The standard 16V set-up is actually quite good and when fitted with an EVO rear bar, very good with less understeer. Problems start when the car is lowered resulting in increased camber all around (within limits, not bad a bad thing except in extreme cases) and a little bit of bump-steer. But you will need stiffer springs to keep the tires from the body work and secondly careful choice of sway bars to keep your now relatively flat cornering car from plowing with increased understeer. Here is a sample of a progressive "up-grade" with 215X40X17 tires & the results: -- Factory 16V: nice handling w/understeer -- Same w/EVO rear bar: less understeer -- Same lowered (63cm ground to fender lip) with H&R springs all round:flatter cornering, same understeer, slight rubbing, increased front & rear neg camber. Rolled fender lips and spaced out front spoiler forward 2-3cm to cure rubbing. All in all an improvement in handling but increased tire wear due to camber. -- Same with 500E front sway bar: Flatter cornering but much too much understeer. -- Same with cut 129/500SL springs all round: Same ride height (63cm), no rubbing, livable but slightly harsh ride, flatter cornering, same (possibly more) understeer. -- Removed 500E bar and refitted 16V front bar: reduced understeer, same flat cornering. -- Alignment set to: Front:camber 1.5, caster 11.0, toe 0.6. Rear: camber1.5, toe 0.12: slightly reduced understeer, good turn in. Tire pressure: 36 front, 34 rear. The increased caster does increase steering effort but the increased directional stability >180kph is reassuring. That is where the car stands now. I am still not 100% happy with the remaining understeer so will pick up a set of 400E front springs, cut them and install them to reduce the front spring rate. This should reduce the cornering load on the outside front tire which should pull back some understeer. The alternate is making and fitting a larger rear bar. I have tried to attach a PDF file of 124 spring specs & part numbers. If it is here fine, if not I will send it to anyone who knows how to attach these things. Regards, bobf. Edited by matsalleh76, Tue Jun 9, 2009 1:58 pm.



dave_irl	Tue Jun 9, 2009 6:34 am Post #5
I love offset. Posts: 8,729 Group: Admin Member #6 Joined: November 2, 2005	Hi Bobf, you can email me the file and I will attach it, thanks. Does it include some spring rates? My car only has occasional understeer at quite slow speeds on more or less full lock on slippy surfaces, otherwise the car tends to oversteer which I am happy enough with. The car feels stable through corners and roundabouts (when grip driving), but I still preferred the stiffer feel when the car was pretty much riding on the bumpstops, so there was very little suspension travel, only whatever flex the stops gave. They were pretty big stops however:



alogaparaloga	Tue Jun 9, 2009 6:59 am Post #6
crazy mind Posts: 602 Group: Members Member #2,419 Joined: March 14, 2008	I am no expert on suspension setup, but to move the car towards oversteer, the rear ARB needs to be much stronger. Additionally we have to keep in mind that 15 years old or more ARBs become softer as they work throughout the years and they loose some of the material due to rust, which changes their mean radius and their mechanical properties. I think it would be ideal to custom build cold formed ARB from spring material. Another option that needs very good planing and I have seen it applied in VW type 2 vans, is to use one more ARB fixed to the original ends. This method is not easy for the 190 rear end but nothing is impossible.



dave_irl	Tue Jun 9, 2009 7:10 am Post #7
I love offset. Posts: 8,729 Group: Admin Member #6 Joined: November 2, 2005	Well I have a new EvoII ARB with the TE metal endlinks, so I'm happy enough with that set up for now, but I really need to get some stiffer springs in there.



Martrider	Tue Jun 9, 2009 7:57 am Post #8
Longest build time in history? Posts: 1,523 Group: Members Member #2 Joined: November 2, 2005	Have you checked out the extra shorts and made sre there is no damage from them hitting the topmounts? You may have done a fair bit of damage/weakening to the strut tops if you've been basically just riding on them as they're not technically designed for it. I really think it would be worth taking it all off and having a proper look dude.



dave_irl	Tue Jun 9, 2009 8:42 am Post #9
I love offset. Posts: 8,729 Group: Admin Member #6 Joined: November 2, 2005	I've had the wheels off and had a look, all seems ok. The rdmtek top mounts seem insanely strong, so I doubt any damage there, and the sheet metal of the car itself is still attached to the chassis so no harm done! Worst case scenario the tube of the damper will be damaged but I doubt it. I've sent a mail to Faulkners to get a rough quote, and I'll come back to them with a spring rate. Does anybody else know any other custom spring manufacturers that are worth checking out for a bit of shopping around?



alogaparaloga	Tue Jun 9, 2009 8:50 am Post #10
crazy mind Posts: 602 Group: Members Member #2,419 Joined: March 14, 2008	UK SPRING MANUFACTURERS ASSOCIATION http://www.uksma.org.uk/ Go to Members and you can browse from there. Hope that helps Edited by alogaparaloga, Tue Jun 9, 2009 8:51 am.



The Gorilla	Tue Jun 9, 2009 10:07 am Post #11
Member Posts: 307 Group: Members Member #3,610 Joined: December 10, 2008	Hi, Dave_Irl- In the real world there is no half way house with regard suspension that is good on the Road and Track. All the requirements for a decent road set up will work for pottering around any Track but as soon as you start to load up the suspension the shortcomings soon become evident. The set up on the JM Motorsport car the Nords 320nm kit will make a daily driver almost undriveable at speed on some UK Roads. Notice that the Nords kit is also a progressive spring so it will allow the car to roll in settle and then roll out agin on corner entry and exit. Road surfaces in mainland Europe fair a little better than here. On my CSL if you push it really hard on the back roads you have a problem that the car starts diving and skiting all over the place, due to its Intrax spring and damper rates, on the Track it comes alive. Even a standard CSL which goes quite well at the Ring, is way to harsh for some folks daily driving. Its a Trade off. I think if you aimed at a Grp N type set up, which if your car is say 55/45 weight split and runs around 1200kg then 180nm front with 140 nm rear would be quite stiff for the raod and keep you honest at speed on most Tracks. You could then always advance to say 200/220 nm fronts but would have tp alter damper rates to make this effective. The Merc 190 suffers from no Front Drop links as such, on the front ARB. So the front ARB is always slightly pre loaded, which means that any inbalance in your spring and damper rates will be instantly felt on turn in. I would keep ther rear bar as small as possible to start with and get the front right, and then introduce a stiffer rear as you go. As Bobf said as well it also depends on how you like your car set up, most aim for neutral or slight understeer, so that understeer increases during corners and can be corrected easily on the throttle. I personally prefer some oversteer so that the car hopefully becomes more neutral in the faster bends. Regards, The Gorilla.



alogaparaloga	Tue Jun 9, 2009 11:31 am Post #12
crazy mind Posts: 602 Group: Members Member #2,419 Joined: March 14, 2008	The Gorilla Tue Jun 9, 2009 10:07 am The Merc 190 suffers from no Front Drop links as such, on the front ARB. So the front ARB is always slightly pre loaded, which means that any inbalance in your spring and damper rates will be instantly felt on turn in. Hi Gorilla, Could you please give some more info on the front ARB? How that preload can be reduced? new mounting points? different shape ARB? Would that preload reduction introduce an increase in the body roll or pitch and yaw? and in what way? Thanks



dave_irl	Tue Jun 9, 2009 11:56 am Post #13
I love offset. Posts: 8,729 Group: Admin Member #6 Joined: November 2, 2005	The Gorilla Tue Jun 9, 2009 10:07 am I think if you aimed at a Grp N type set up, which if your car is say 55/45 weight split and runs around 1200kg then 180nm front with 140 nm rear would be quite stiff for the raod and keep you honest at speed on most Tracks. You could then always advance to say 200/220 nm fronts but would have to alter damper rates to make this effective. Thanks for the advice. When you say alter damping rates, is this the compression/rebound damping that I can adjust on my current dampers? Or is it a more thorough modification by stripping them and revalving their insides etc? I got a reply from Faulkners: Quote: Dave, Not sure if we can help ,If you double spring rate and try to give car that -60 mm drop the springs would be very short can you work with that. You would have to send us one front and rear with fitted lengths of springs on car we would design a spring but being very short it may not give spring travel required Regards Peter I think I know what he's getting at, the car could sit higher than before? As what I'm aiming to do is reduce the suspension travel to stop the damper bottoming out.. But maybe he doesn't know what I'm trying to say. If the stronger springs were of the same free length as mine, then the installed length couldn't be less than the current ones as they would be a stronger spring and therefore harder to compress? Unless the problem is that the stronger spring means more coils, and if the spring is already relatively short, the coils would bind earlier and I would have very little travel, which is just as bad I guess... Though I thought some springs had very open "windings" with lots of space between the coils, can you not get those in high spring rates?



bri957	Tue Jun 9, 2009 12:56 pm Post #14
Member Posts: 1,468 Group: Members Member #1,134 Joined: April 2, 2007	Dave I think it may be worth buying a set of standard 500SL R129 springs and chopping them... Not ideal, but as a short term ghetto solution, may be what you need.



JM Motorsport	Wed Jun 10, 2009 8:16 am Post #15
Member Posts: 902 Group: Members Member #398 Joined: July 11, 2006	Dave, if you contact H&R they can supply springs for the w201 in a wide range of spring rates. Just ask for the Gruppe G range of springs.



The Gorilla	Wed Jun 10, 2009 8:44 am Post #16
Member Posts: 307 Group: Members Member #3,610 Joined: December 10, 2008	Hi, Dave_irl- correct, the adjustment you have is for the rate it reacts at, not the rates at which it works. You would require a re-valve, which might not be possible on your current set up, or new dampers etc. Alogaparaloga- the Merc 190 ARB's I would guess are neutral at the car's original ride height. When you then lower car you will load up the Front ARB as the wishbones it attaches to are now sat up higher than standard. When you have drop links you can shorten the drop links to suit the cars new ride height. Many coilover kits come with shorter or adjustable drop links to compensate for the drop in ride height. The Merc 190 rear has drop links, so the easy fix here would be to replace the fixed existing drop links with adjustable ones. On the front, and I have only seen a 2.6 recently, the front ARB is suspended down on extension bars from the main chassis rail and the sump pan has an indent at the front for the ARB to clear and move in. Ideally, the front ARB wants fixing/locating directly onto the chassis rail which will cause sump clearance issues on the 2.6, but I guess not on a 4 pot ? Then you can attach the ends of the ARB to the front wishbones with drop links, that can be adjustable so that when the car is lowered, any pre-load can be removed of the ARB. I would guess that while it seems that some have opted for thicker front ARB's, E500 seems to be mentioned ? on a lowered car, while it will feel much tighter at the front, it is actually working againts the basic princpal of what and how a ARB is supposed to work. The original front ARB if set up correctly with drop links and no pre-load would be more than capable until you start getting into much higher mechanical grip levels, which could only be generated with 2/3 way adjustable suspension for height, bump and rebound, and at least Type R tyre compounds. The stiffer rear bar requirement is more than likely born out by the fact that it requires tightening up due to the increased stiffness of the front now not working correctly. The fact is, take any car, set it up correctly on its existing suspension and correct tyre pressures and it will feel transformed. My son recently did a survey for a new business he is looking at, and of 750 cars checked over a two week period, only 3 had the correct tyre pressures. I can't get the right air pressure in my tyres cost 20p, but 2k of suspension will make it handle better !!! Regards, The Gorilla.



dealgan	Wed Jun 10, 2009 9:04 am Post #17
Member Posts: 961 Group: Members Member #902 Joined: February 4, 2007	This is interesting. I never thought about the front ARB being affected by having shorter springs to start with. where's the "scratches chin" smiley ?



dave_irl	Wed Jun 10, 2009 9:26 am Post #18
I love offset. Posts: 8,729 Group: Admin Member #6 Joined: November 2, 2005	JM Motorsport Wed Jun 10, 2009 8:16 am Dave, if you contact H&R they can supply springs for the w201 in a wide range of spring rates. Just ask for the Gruppe G range of springs. Thats great, thanks Mikael, I didnt know that. I just sent an email to my friendly H&R email girl - and we'll see what happens. I hit a bit of a wall with Faulkners so thats a no go there.. Oh I forgot to attach the file that Bobf. kindly sent me, here it is: Attached to this post: 124_coil_spring_specs.xls (32.5 KB)



dave_irl	Wed Jun 10, 2009 9:31 am Post #19
I love offset. Posts: 8,729 Group: Admin Member #6 Joined: November 2, 2005	dealgan Wed Jun 10, 2009 9:04 am This is interesting. I never thought about the front ARB being affected by having shorter springs to start with. where's the "scratches chin" smiley ? I didn't either, but it soon becomes apparent when try to do some suspension work with the ARB in place! Its under alot of preload - the lower you go the harder it gets. Sometimes I think improving on thing just moves or creates a problem somewhere else



dave_irl	Wed Jun 10, 2009 12:48 pm Post #20
I love offset. Posts: 8,729 Group: Admin Member #6 Joined: November 2, 2005	Hmm, not much joy here either.. Quote: Hi Dave, I chekced and we have no Gruppe G springs for the 4-cylinder models. So no springs based on 29613-1. There are only a few based on 29614-1 which is a spring set for the 2,3l 16V models in different spring rates. Although their shape would fit your car there will be no lowering with these in your car as the 29614-1 springs are a lot stronger for the increased weight of the 2,3l 16V. Sorry, but this time I couldn�t really help. Regards Yvonne ..Unless I got a set designed for a 16v and cut a coil or two off? this is getting frustrating - the car is almost undriveable, Im going to have to get the grinder to remove the damages arch metal tomorrow before it destroys even the 185 tyre..



bri957	Wed Jun 10, 2009 1:03 pm Post #21
Member Posts: 1,468 Group: Members Member #1,134 Joined: April 2, 2007	Dave, in the meantime just chop some w124 S6 or V6 springs. Should cost buttons and prevent further damage to tyres and arches.



NEIL	Wed Jun 10, 2009 1:07 pm Post #22
Fewer Posts than Kenny Posts: 16,131 Group: Members Member #63 Joined: November 18, 2005	Dave, you gotta change your Avatar subtitle to read 'Junior Tuner Xtraordinaire'...



dave_irl	Wed Jun 10, 2009 9:23 pm Post #23
I love offset. Posts: 8,729 Group: Admin Member #6 Joined: November 2, 2005	NEIL Wed Jun 10, 2009 1:07 pm Dave, you gotta change your Avatar subtitle to read 'Junior Tuner Xtraordinaire'... Oh if only you saw how I "tuned" my arch tonight! picture rattle can, snips, file, BFH, and a vice grips.. Had to remove the damage, looks mank but should work! Discovered filler too so looks like the wing wasnt the best to begin with anyway.. Passenger side is mostly ok. Now I have my bodyshop quote I have some kind of vision in my head it will make it there some day. So at the mo she is most definitely "rat look drifter" Still have the bottoming out/knocking though. I think you are onto something Bri, time for a cheap solution! F*** it I might just buy another set of bumpstops for the time being - other ones lasted nearly 6 months!



dennisbots	Thu Jun 11, 2009 4:30 am Post #24
Member Posts: 554 Group: Members Member #1,903 Joined: November 10, 2007	Btw my H&R spring rate is 220nm/mm for the rear and 340nm/mm for the front. It will be stiff but my car is also heavier (stock 1290kilo + all the aftermarket stuff that comes on the engine +big brake's etc)



Johnboy Mac	Thu Jun 11, 2009 7:25 am Post #25
Member Posts: 1,608 Group: Members Member #2,771 Joined: June 12, 2008	Dave, worth a shot to contact Leda. www.leda.com sales@leda.com 01332 8718321 Edited by Johnboy Mac, Thu Jun 11, 2009 7:26 am.



tomas	Thu Aug 20, 2009 10:03 pm Post #26
Newbie Posts: 6 Group: Members Member #2,099 Joined: January 2, 2008	Hi, I need some help here. I've been trying to find a good setup for racing, but I haven't found something I like. When I use to drive my car on street I use yellow koni sport on front sls on back and H&R spring all around. The car feel fine, soft in the rear but ok for street driving. Then I get rid of the sls and install make my custom shorter shock, leaving the H&H. As you may know those spring were made for the SLS exclusibly, later I try cut 320e spring and the car feel the same (very very soft). I thought something stupid and unfortunately I do it, I cut OEM front spring and install them on the rear, just to feel it (cut them a lot to bring the weight to the rear). I fell good on the back, seams the spring shock combination work good, but obviously I have planty of overstreering. I need to know if I could go further with these springs? How stiff are front oem to the H&R? If possible to correct the understeering matching the front suspension to the rear with other spring?. I don't know if the oversteering came from the excessive stiffness, I have a lot of camber and my tires aren't sticky. Thanks. edit>oversteer. Edited by tomas, Thu Aug 20, 2009 10:31 pm.



alogaparaloga	Thu Aug 20, 2009 10:10 pm Post #27
crazy mind Posts: 602 Group: Members Member #2,419 Joined: March 14, 2008	Your problem for oversteer - understeer is not due to the springs. You need a thicker antiroll bar at the rear end, or to remove the preload from the front ARB. because when you lower the car you compress the ARBs at front and rear. It is very important to maintain a balance of the load on ARBs. Edited by alogaparaloga, Thu Aug 20, 2009 10:12 pm.



khimani_mohiki	Fri Aug 21, 2009 8:14 am Post #28
Member Posts: 336 Group: Members Member #3,735 Joined: January 16, 2009	so what about fabricating shorter ARB brakets to suit the shorter springs?



alogaparaloga	Fri Aug 21, 2009 8:48 am Post #29
crazy mind Posts: 602 Group: Members Member #2,419 Joined: March 14, 2008	one method can be that, the other method can be adjustable brackets on the wishbones



feoffle	Fri Aug 21, 2009 9:31 am Post #30
Member Posts: 184 Group: Members Member #4,315 Joined: June 23, 2009	Just thought I'd add, choosing spring rates will depend mostly on the dampers you choose, and how well valved they are. if you use spring rates that are beyond the capabilities of the dampers, they'll be overly-harsh, bouncy and horrible.



bolide	Fri Aug 21, 2009 9:28 pm Post #31
Bolide Posts: 193 Group: Members Member #3,828 Joined: February 11, 2009	Hang on a second! I've never seen an ARB setup where the bar is solidly attached. It's always floating in a bush. So how does preload work? If the bar is free to rotate in a bush then lowering the car won't affect the ARB at all unless it fouls or unless the geometry of it changes radically How does lowering the car affect this? Nick Froome Edited by bolide, Fri Aug 21, 2009 9:29 pm.



bolide	Fri Aug 21, 2009 10:17 pm Post #32
Bolide Posts: 193 Group: Members Member #3,828 Joined: February 11, 2009	WRT spring rate, you can't compare rates between dissimilar cars without taking into account the motion ratio MR for a Macpherson strut is nearly 1:1 and for an W124 I estimate is about 0.25. So spring rates for W124s are pretty high. Hence 4" diameter springs that look like they'd support a truck - but a soft ride Spring rate calculator http://www.stockcarproducts.com/pstech9.htm ARB rate calculator http://buildafastercar.com/tech/Sway-Bar-Rate-Calculator Other calculators http://www.swayaway.com/calculators/swayawayCalc.php The lower the motion ratio the harder the spring has to be, all things being equal. Which means thicker wire and, for a given spring length, less travel before being coilbound I did some back-of-an-envelope calculations a while ago. From memory: If a car weighs about 1500 Kg (W124) and has a 60/40 weight distribution, each front spring supports 450 Kg. Free spring length I estimate to be about 15" and spring length at static ride height about 7.5". So 450 Kg (or 990 lbs) compresses the spring 7.5" so logically spring rate is 1584 lb/ft. Except it's not - because of the MR I estimated the wishbone pivot-to-hub length (a) to be twice that of the pivot-to-spring seat (b) MR = (b/a) squared = 0.25. Clearly this estimate doesn't have to be too far out to ruin the estimates or calculations... I estimate a W124 front wheel rate to be 250-300 lb/ft so the spring rate would be 1000-1200 lb/ft - ie a big spring! Going back to my spring length estimates, if we assume the spring is just decompressed at full droop then 7.5" of spring travel = about 15" of wheel travel for 450 Kg. Or 360 lb/ft wheel rate and 1440 lb/ft spring rate. That's not too far off my spring rate estimate Going further, if the coil is 50% shorter at static ride height then quite a lot of available bump travel is already taken up. There's maybe another 2.5" of bump travel left, or about 5" at the wheel (based on an estimate that the spring is 5" long when coilbound) and lots and lots of droop travel. I've never bottomed out the front suspension of a W124 so clearly the fundamental spring rates & travels are well-judged and it has good progressive bump stops! Another thing that came out that I found interesting was that suspension frequency is independent of spring rate. That makes no sense on the face of it - surely a stiffer suspension has a higher frequency? It doesn't, though. Frequency is dictated by suspension travel. So for a low frequency (around 1-2 Hz for a comfortable ride) you need more suspension travel than for a sports car (2-5 Hz). This is why W124s, early Range Rovers and Citroen BXs are comfortable - lots of travel It follows that to keep the natural frequency similar front & rear the travel needs to be similar. As the rear weighs less than the front (of most saloon cars) it follows that the wheel rate must be lower than the front BTW there are some major-league assumptions here and, no doubt, a few mistakes, For example, wheel rate can't be directly calculated off spring rate as it depends on the unsprung weight. Something you guys with 18" rims find out every day... If anyone has accurate figure for any of this I'd love to see them! Nick Froome Edited by bolide, Fri Aug 21, 2009 10:43 pm.



1 user reading this topic (1 Guest and 0 Anonymous)


« Previous Topic · Track/Racing Section · Next Topic »