Olythekid Posted October 9, 2019 Report Share Posted October 9, 2019 I called Ground Control to install their coilover kit on my 86 635CSI. They advised 650lb on 6' front and 500lb on 8' back. 635s are heavy cars at 3,000lb-ish but do these rates/lenght look 'ok' for you? I so some guys on forums going as high as 800lb square. Quote Link to comment Share on other sites More sharing options...
Originalsterm Posted October 10, 2019 Report Share Posted October 10, 2019 Have you corner weighed your car? What sways are you running? Do you have dampers to match those spring rates? The numbers might be fine for a track 635, maybe not a full on race car though. Quote Link to comment Share on other sites More sharing options...
Olythekid Posted October 10, 2019 Author Report Share Posted October 10, 2019 The sway bars are stock for now. The Blistein shocks B8 will be re-valved. I read 800lb on a website somewhere of a guy running a 635, but when I talked to Ireland they said it's too stiff. Everyone seems to have their own truth, that's why I'm asking here before I pulled the trigger on some setting good enough as a baseline. Quote Link to comment Share on other sites More sharing options...
Technical Advisory Committee Chris Huggins Posted October 10, 2019 Technical Advisory Committee Report Share Posted October 10, 2019 Not many people run E24's in champ. I know of two really - @Jim and a team in florida with an M6. Spring rates are specific to chassis, not car brand, because each vehicle has different motion ratios, suspension designs, etc. Spring rates are also different depending on tracks raced at. They can be dependent on Aero, Tires, Bushings, Brakes, etc. They are very dependent on vehicle weight, so how much stuff are you stripping out of the car? Lastly, they can be dependent on driving style. So, honestly, everyone has their own truth because everyone actually has their own truth. For street cars or HPDE work, or for a "for fun" champcar, almost any spring rate will be good enough. If you are looking to be super competitive, your team will need to do some experimenting to determine your optimal spring/shock package with your build. 1 Quote Link to comment Share on other sites More sharing options...
Technical Advisory Committee Andrew D Johnson Posted October 10, 2019 Technical Advisory Committee Report Share Posted October 10, 2019 There is no "right" spring rate. I would measure the stock spring rates, and go 25 - 33% stiffer than stock and give that a try. 1 Quote Link to comment Share on other sites More sharing options...
theblue Posted October 10, 2019 Report Share Posted October 10, 2019 (edited) +1 everything you're reading about online for a car like this is probably dealing with street weight / setup cars. I expect there will need to be some development work for this platform in terms of finding a good balance. Billy B8s are probably great out of the box as they effective goes up and the weight goes down. They're magically perfect as is on our E36. Edited October 10, 2019 by theblue Quote Link to comment Share on other sites More sharing options...
wvumtnbkr Posted October 10, 2019 Report Share Posted October 10, 2019 1 hour ago, red0 said: There is no "right" spring rate. I would measure the stock spring rates, and go 25 - 33% stiffer than stock and give that a try. Whoa. That would be interesting on my rx7. That would mean about 130# springs front and rear. Quote Link to comment Share on other sites More sharing options...
Technical Advisory Committee Andrew D Johnson Posted October 10, 2019 Technical Advisory Committee Report Share Posted October 10, 2019 35 minutes ago, wvumtnbkr said: Whoa. That would be interesting on my rx7. That would mean about 130# springs front and rear. I can't imagine it would be too interesting, the RX7 was the top of the line mazda sports car with springs designed for the car at full weight. Lightening the car and then stiffening the rates 25-33% would be where I would have started. Just my thoughts....... Quote Link to comment Share on other sites More sharing options...
JDChristianson Posted October 10, 2019 Report Share Posted October 10, 2019 13 minutes ago, red0 said: I can't imagine it would be too interesting, the RX7 was the top of the line mazda sports car with springs designed for the car at full weight. Lightening the car and then stiffening the rates 25-33% would be where I would have started. Just my thoughts....... Not bad logic, and it would probably work but not be optimum. In Miata land that I have a bit of experience with you end up more like 4 or 5 times the original rate. It’s also very platform specific and then driver preference specific. (My experience is mostly following recipes that others have developed over the last 3 decades of Miata’s) Quote Link to comment Share on other sites More sharing options...
tommytipover Posted October 10, 2019 Report Share Posted October 10, 2019 47 minutes ago, JDChristianson said: (My experience is mostly following recipes that others have developed over the last 3 decades of Miata’s) OMG it has been that long... man, that makes me feel old. "30 years ago" sounded a lot longer when I was young. 2 Quote Link to comment Share on other sites More sharing options...
Olythekid Posted October 10, 2019 Author Report Share Posted October 10, 2019 (edited) I understand it is car specific. My question was more on the principle as the values provided by the coilover provider means nothing to me. Let's take an E30 then. Do you guys run heavier springs on the front? What is the difference between front and back? Is it the same? 50lb? 300lb? Did you had to revalve when you got 30% stiffer springs? Edited October 10, 2019 by Olythekid Quote Link to comment Share on other sites More sharing options...
jakks Posted October 10, 2019 Report Share Posted October 10, 2019 9 minutes ago, Olythekid said: I understand it is car specific. My question was more on the principle as the values provided by the coilover provider means nothing to me. Let's take an E30 then. Do you guys run heavier springs on the front? What is the difference between front and back? Is it the same? 50lb? 300lb? Did you had to revalve when you got 30% stiffer springs? Front/Rear 118/265-stock 315/570- H&R race/old spece30 535/700- new SpecE30 Ground Control GC and Bisltein says the Bilstein sports can handle the new suspension just fine. Whether that would be true for you Billy’s I’m not sure. E24 is probably more front heavy so you need the extra rate up front. They are also maybe taking into account stock sway bars and such. There are many different variables. I would try their rates, if you don’t like them then go up another 50-100#. Quote Link to comment Share on other sites More sharing options...
enginerd Posted October 10, 2019 Report Share Posted October 10, 2019 24 minutes ago, Olythekid said: I understand it is car specific. My question was more on the principle as the values provided means nothing to me. Let's take an E30 then. Do you guys run heavier springs on the front? What is the difference between front and back? Is it the same? 50lb? 300lb? Did you had to revalve when you got 30% stiffer springs? The e30 is an odd duck for suspension geometry, rear spring sits halfway along the moment arm. Rear spring rates are probably double the front rates, even if the wheel rates are similar. I don’t know our e30 spring rates... we reached our current settings over seasons of racing and tweaking rather than picking rate numbers from the get-go. Also, our setup isn’t optimized either. We got the suspension / handling to a point that we all liked and that’s where we stayed. 1 Quote Link to comment Share on other sites More sharing options...
Olythekid Posted October 10, 2019 Author Report Share Posted October 10, 2019 Wow Jakks, so much softer on the front. I think I need stiffer on the front due to the weight of that 3.5L. Like Enginerd said, I need to start with something and see what works and doesn't. I hope I will not have to $$$ revalve everytime. I wished the rules were kinder on the points for adjustable shocks to save on money. Quote Link to comment Share on other sites More sharing options...
enginerd Posted October 10, 2019 Report Share Posted October 10, 2019 (edited) 45 minutes ago, Olythekid said: Wow Jakks, so much softer on the front. I think I need stiffer on the front due to the weight of that 3.5L. Like Enginerd said, I need to start with something and see what works and doesn't. I hope I will not have to $$$ revalve everytime. I wished the rules were kinder on the points for adjustable shocks to save on money. Simple, don’t revalve. Put in bilsteins and then tune solely with spring rates. That’s what we did and we’re pretty quick. Also, the motion ratio is the reason why e30 spring rates are they way they are. It’s like .80 front and .50 rear. If the e24 motion ratios are closer to equal, then your spring rates should be closer to equal than the e30 rates. Edited October 10, 2019 by enginerd Quote Link to comment Share on other sites More sharing options...
ABR-Glen Posted October 10, 2019 Report Share Posted October 10, 2019 Actually, the motion ratio gets gets squared so, if the spring were moved half way closer to the pivot you would need to quadruple the spring rate to keep everything else the same. Point being, spring rates alone mean almost nothing unless you know the layout of the suspension geometry (although I assume it's still struts in front so that is relatively strainghtforward) 2 1 Quote Link to comment Share on other sites More sharing options...
wvumtnbkr Posted October 10, 2019 Report Share Posted October 10, 2019 3 hours ago, red0 said: I can't imagine it would be too interesting, the RX7 was the top of the line mazda sports car with springs designed for the car at full weight. Lightening the car and then stiffening the rates 25-33% would be where I would have started. Just my thoughts....... The car rolls an awful lot on sport type springs. It is also harder to drive at the limit. We are about 4.5 x stock in (macstrut) front and about 3x stock in the rear. Car is still considered soft by some people's standards when. They drive it. Quote Link to comment Share on other sites More sharing options...
Olythekid Posted October 10, 2019 Author Report Share Posted October 10, 2019 1 hour ago, enginerd said: Simple, don’t revalve. Put in bilsteins and then tune solely with spring rates. That’s what we did and we’re pretty quick. Also, the motion ratio is the reason why e30 spring rates are they way they are. It’s like .80 front and .50 rear. If the e24 motion ratios are closer to equal, then your spring rates should be closer to equal than the e30 rates. The GC guy said if I don't revalve I'll tear up the Blisteins pretty quickly. The heck I know. I guess I'll have to start by finding what is the weight distribution of the 635 then figure out how to find that 'motion ratio' thingy. Thank you for the insight s. Quote Link to comment Share on other sites More sharing options...
jakks Posted October 10, 2019 Report Share Posted October 10, 2019 10 minutes ago, Olythekid said: The GC guy said if I don't revalve I'll tear up the Blisteins pretty quickly. The heck I know. I guess I'll have to start by finding what is the weight distribution of the 635 then figure out how to find that 'motion ratio' thingy. Thank you for the insight s. Talk to a Bilstein rep. They will tell you what your specific Sports are allowed to handle. Quote Link to comment Share on other sites More sharing options...
Olythekid Posted October 10, 2019 Author Report Share Posted October 10, 2019 Good point. Quote Link to comment Share on other sites More sharing options...
Jim Posted November 13, 2019 Report Share Posted November 13, 2019 On 10/9/2019 at 4:07 PM, Olythekid said: I called Ground Control to install their coilover kit on my 86 635CSI. They advised 650lb on 6' front and 500lb on 8' back. 635s are heavy cars at 3,000lb-ish but do these rates/lenght look 'ok' for you? I so some guys on forums going as high as 800lb square. Baby lasershark has 600 lbs up front. I'm not sure about the rear. Racebar has 200 lbs all around with blown out shocks and it races just fine. It has at times been faster than e30's, such as the winsome racing e30 with @bendawson3 driving Racebar. My opinion is your way overthinking it. But what do I know, I drive a car with a bar on it. 3 Quote Link to comment Share on other sites More sharing options...
Guest E. Tyler Pedersen Posted November 13, 2019 Report Share Posted November 13, 2019 I've never measured but I've tested a lot of setups. I'm testing another one soon to make sure our E30 is magical. Start with something stiffer than adjust from there. Also I had no clue where to start and got some good advice from rental drivers. Really I've had about 10-15 people help setup the car Quote Link to comment Share on other sites More sharing options...
wvumtnbkr Posted November 13, 2019 Report Share Posted November 13, 2019 Find out what good sport spring values are. Double that. Good starting point. Quote Link to comment Share on other sites More sharing options...
frankrehnelt Posted November 14, 2019 Report Share Posted November 14, 2019 We have gone from cut stock springs to 700/1000 and the cars get better and better. Quote Link to comment Share on other sites More sharing options...
Originalsterm Posted November 14, 2019 Report Share Posted November 14, 2019 23 minutes ago, frankrehnelt said: We have gone from cut stock springs to 700/1000 and the cars get better and better. What dampers do you run with those spring rates? Quote Link to comment Share on other sites More sharing options...
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