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Rear Spring

Which rear spring should I test?


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bnightstar

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I'm on a 450#/in front spring and I've played around with the rear, all on Magneride. This is just more playing around. If I were going out for qualifying next session, I'd be on your setup. I just wanted to feel what something "too soft" would feel like. If the front is properly supported, then are we *really* sure it's "too soft?" I don't know know the answer to these questions, but I'm going to find out. I've got 650, 750, 850, and 950 pairs sitting in a tote.
With 450 front and 500 rear on conventional spring location you will have like 200 lbs or so wheel rate in the rear the car will understeer and with OEM dumpers will ether be way out of the control settings for the Magneride or bouncing like crazy over bumps. You have to consider that putting to soft springs on a shock may lead to blown shocks as well. Overall I think it's an interesting experiment.

Мy point was that I like my rear feel better with the 800 lbs spring than the 740 spring before it. Sure the Ohlins shocks that are amazing.

I can tell you that the Ohlins setup is faster than a M1 Magneride setup.
I did test against an A10 M1 both cars on 255/275 street tires and the Ohlins setup was faster.
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TeeLew

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BNight- You've got 2 data points in terms of springs/dampers if I'm not mistaken? The change from PP dampers to Ohlins is chalk and cheese. That alone would be a massive change. You also raised the front spring by 300%, which anyone who has tried says gives great benefits. Then you raised the rear spring by 8%, which is not going to be noticeable if you're doing all that other stuff. Don't take this the wrong way, but you don't really know the difference between 740's and 800's rears on your car because you changed so much other stuff at the same time.

Let me suggest that Ohlins are a massive gain, I don't have them so I've got to p-ss with the d-ck I've got and use the Magnerides. Let's also note that the Ohlins package shifted the roll couple significantly towards the front of the car *while reducing understeer*. Books say that doesn't happen. It does.

This is an experiment, because that's the type of stuff I do. 4 years ago on this board most were running around with rear springs roughly 4x the front rate (e.g. 200#/in front and 800#/in rear) and 'Flat Ride' was the Holy Grail. At the very least, I feel I've been able to put that to bed although some still has some who prefer this, which is fine. For a long time, I was the only guy that was stupid enough to put a big front spring on the car. There was another guy that used to do a lot of suspension work here and he was a smart dude. He was just a little inexperienced and a little too into book world, so he was a big fan of soft front/stiff rear spring. I was in the same place 25-30 years ago and have since changed my views.

I'm not making any claims on what the spring will or won't do. I'm just going to go see. I've made a lot of spring changes on I don't know how many cars and I have yet for a softer (or stiffer) one to hurt a damper. Not that it can't happen, but it hasn't, yet.
 

bnightstar

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BNight- You've got 2 data points in terms of springs/dampers if I'm not mistaken? The change from PP dampers to Ohlins is chalk and cheese. That alone would be a massive change. You also raised the front spring by 300%, which anyone who has tried says gives great benefits. Then you raised the rear spring by 8%, which is not going to be noticeable if you're doing all that other stuff. Don't take this the wrong way, but you don't really know the difference between 740's and 800's rears on your car because you changed so much other stuff at the same time.


I'm not making any claims on what the spring will or won't do. I'm just going to go see. I've made a lot of spring changes on I don't know how many cars and I have yet for a softer (or stiffer) one to hurt a damper. Not that it can't happen, but it hasn't, yet.
I actually think a bit more rear spring will be beneficial with my setup but as you said it may be because of the 515 front springs. I think 900's will be better and this is because I'm heaving controlling what is going up in the rear is compliant but not compliant enough over bumps and such. For sure need more spring on the back.
 
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TeeLew

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I actually think a bit more rear spring will be beneficial with my setup but as you said it may be because of the 515 front springs. I think 900's will be better and this is because I'm heaving controlling what is going up in the rear is compliant but not compliant enough over bumps and such. For sure need more spring on the back.
That could very well be. Your home track has a fair bit of elevation change, right?
 

bnightstar

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That could very well be. Your home track has a fair bit of elevation change, right?
Nope my home track is flat but really bumpy the pavement is crap on it so I run the Ohlins very soft. And because of the bumps I need more rear spring to control the rear. The other track near me is with new pavement and there this springs work great as well. But again the rear for me needs a bit more I might test 900 eventually.
 

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TeeLew

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There are 2 types of bumps, rollers where the whole chassis moves and sharp, chatter bumps which just the wheel moves. Which type are the bumps you're talking about?

Stiffer springs over bumps to reduce chassis motion is not my normal path because it tends to hurt grip. Generally, I try to get the car to accept them. Sometimes that's just not an option, though.
 

bnightstar

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There are 2 types of bumps, rollers where the whole chassis moves and sharp, chatter bumps which just the wheel moves. Which type are the bumps you're talking about?

Stiffer springs over bumps to reduce chassis motion is not my normal path because it tends to hurt grip. Generally, I try to get the car to accept them. Sometimes that's just not an option, though.
At my local track we some how have both as the curbs are high and very broken the car literally has to jump over the first turn in order to be fast and you need to do that on throttle if possible. And then you have a lot of bumps in brake zones etc. You need a car that's soft but not too soft to loss control of the body. I'm not sure what track in USA is similar maybe Sebring.
 

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In case I missed it, does anyone know what the front and rear Magneride spring rates are? Wondering how much the BMR SPH767R rear springs, coupled with the factory Magneride struts/springs and front sway bar delete will benefit me on the drag strip? FYI, rear shocks are Ultra Spec Inverted Double Adjustsble Viking shocks.
 
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TeeLew

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In case I missed it, does anyone know what the front and rear Magneride spring rates are? Wondering how much the BMR SPH767R rear springs, coupled with the factory Magneride struts/springs and front sway bar delete will benefit me on the drag strip? FYI, rear shocks are Ultra Spec Inverted Double Adjustsble Viking shocks.

They're the PP rates, so something like 170#/in front and 730#/in rear. You don't want Magneride.
 

NGOT8R

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They're the PP rates, so something like 170#/in front and 730#/in rear. You don't want Magneride.
Oh ok, thanks. I ended up going with the BMR Magneride drag springs to try and keep the PCM happy. I have homemade shock delete sensors on the rear and they seem to be working great. I will also be running Steeda 1/4” spring spacers with the BMR springs, as I don’t really want to lower the rear.

I’m not well versed in suspension setup, but I’m hoping that this hybrid combination would help transfer the weight to the rear and make for better short times.
 
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TeeLew

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Are all they body panels the same color?!

I am only messing with ya. Your car sounds like quite the combination of S550 parts from across the platform. And some custom bits as well.
Ya, a little bit of everything. It looks very stock. The windows are tinted and it has a 15-17 GT350 rear spoiler. I guess it sits a little lower than stock, but it's not dumped. You can' only start noticing things when you jack it up. It's just a lot of little things.

My car is Magnetic Metallic, but I've got a bright yellow decklid in the garage that will carry a big spoiler at some point. I'll probably just put some black wrap on it and only use it for track duty. I have to say, it did make me think about what you wrote, though, because my car *could* have a yellow trunk lid!
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