Coil overs springs rate for a street?

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John V
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Re: Coil overs springs rate for a street?

Post by John V » Wed Dec 23, 2015 4:22 pm

Late to the part but it has to be said: One day you guys here will stop acting like its sane to talk about any spring without referencing what the damper is that is controlling it..

And of course without knowing what the damper actually makes for resistance means talking of that in isolation is meaningless..

And finally, how much travel? That goes to spriing rate---and that bears on the damping needs...


And without having a baseline, everything becomes speculation and fapping.

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Re: Coil overs springs rate for a street?

Post by GPz11 » Wed Dec 23, 2015 4:27 pm

I'm running 300's with Koni Yellows.

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Re: Coil overs springs rate for a street?

Post by In XS 7 » Wed Dec 23, 2015 5:19 pm

Yes, me to, I got koni yellows and will have the 300 springs.
Miguel.
89 XR4Ti Monique; Waking up a real "Night/Mare-Coor".
T5, NPR IC, PIMP ECU, Walbro 255, Dual piston BOV, Manual BC, 3" exhaust, One piece Aluminum drive-shaft, mc2 LSD, Boport 1.5 cam, Ported and polish head, big valves, 80# injectors, Bob's log, (soon HY35).

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Re: Coil overs springs rate for a street?

Post by Ghost » Thu Dec 31, 2015 6:47 pm

I'm running 250lb Eibach springs with koni yellows up front. IIRC the springs are 10" long to allow the full travel on the struts - I had 8" 225lb springs before and ran into coil bind as well as the upper mount & threaded sleeve bind.
'85 XR4Ti: 8.8+T56 swap, AEM standalone, HY35 on a full rebuild... What's the bluebook on these cars again?
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Re: Coil overs springs rate for a street?

Post by xr4x4ti » Wed Jan 06, 2016 10:27 am

Ghost wrote:I'm running 250lb Eibach springs with koni yellows up front. IIRC the springs are 10" long to allow the full travel on the struts - I had 8" 225lb springs before and ran into coil bind as well as the upper mount & threaded sleeve bind.

This is VERY important! Please read this again.

I got burned by this bad. I really don't want to through MC2 racing under the bus, but quite a few years ago I purchased a coil over conversion kit from them with a 8in - 225lb/in spring and I was shocked when the ride was extremely harsh. After looking at it installed, it was quite obvious that the spring was near its solid height sitting still. Just because a 300 or 350lb/in spring works at a certain free length, doesn't mean a softer spring will. You have to do the math based on the corner weight, the desired compression travel and the advertised solid height of the spring.

On my current setup, I wanted lots of travel and still wanted the spring completely above the tire and I ended up with some Swift barrel shaped springs that have a lot more travel for any given free length. Another option is to buy the adapters and use 5in diameter springs. The larger the od of the spring is, the more travel it will have for any given spring rate and free length.

Just trying to share,
Tim
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James Wieler
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Re: Coil overs springs rate for a street?

Post by James Wieler » Wed Jan 06, 2016 10:48 am

Yes, thanks for making that clear Tim, you're right you have to do some calculations. My 350's were 7" long and went solid over the slightest bump. I could reduce this by going to full stiff with the Koni yellows. My 300's are 8" long and bind much less often even though they are softer. I did the calculation and figured the compressed height difference was about 0.3" so I am only gaining 0.7" of travel, but this makes a difference.
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Re: Coil overs springs rate for a street?

Post by hEaT » Wed Jan 06, 2016 11:10 am

That's interesting...how tall are the stock springs at 97lb/in?
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Re: Coil overs springs rate for a street?

Post by In XS 7 » Wed Jan 06, 2016 1:04 pm

What if you use the "helpers" (spring helpers) that are offered from mc2? did they help? or, it doesn't matter if you use them or not? the problem is that the main springs are only 8" instead of 10" long?
Thanks for the tips.
:cheers
Miguel.
89 XR4Ti Monique; Waking up a real "Night/Mare-Coor".
T5, NPR IC, PIMP ECU, Walbro 255, Dual piston BOV, Manual BC, 3" exhaust, One piece Aluminum drive-shaft, mc2 LSD, Boport 1.5 cam, Ported and polish head, big valves, 80# injectors, Bob's log, (soon HY35).

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Re: Coil overs springs rate for a street?

Post by hEaT » Wed Jan 06, 2016 1:13 pm

In XS 7 wrote:What if you use the "helpers" (spring helpers) that are offered from mc2? did they help? or, it doesn't matter if you use them or not? the problem is that the main springs are only 8" instead of 10" long?
Thanks for the tips.
:cheers

I don't think it would do much. They're completely compressed at static ride height. They only do anything when the suspension becomes unloaded. They add maybe 1/2" of ride height.
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Re: Coil overs springs rate for a street?

Post by GPz11 » Wed Jan 06, 2016 2:19 pm

What spring are you looking for? I've got a few sets on the shelf in the basement. I might have what you are looking for.

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Re: Coil overs springs rate for a street?

Post by hEaT » Wed Jan 06, 2016 2:37 pm

I have two set here too, 350lb and 500lb if anyone is interested.
Joe
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Re: Coil overs springs rate for a street?

Post by In XS 7 » Wed Jan 06, 2016 4:37 pm

Hi guys, I already order the coil over kit with 300# springs and helpers on Dic the 23rd, but since they were on vacations I have to wait, they will ship the kit this weekend, which is fine with me cause I am in no hurry, but I keep looking to the replies and learn from the tips and experience of all of you. Thank you very much.
:cheers
Miguel.
89 XR4Ti Monique; Waking up a real "Night/Mare-Coor".
T5, NPR IC, PIMP ECU, Walbro 255, Dual piston BOV, Manual BC, 3" exhaust, One piece Aluminum drive-shaft, mc2 LSD, Boport 1.5 cam, Ported and polish head, big valves, 80# injectors, Bob's log, (soon HY35).

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Re: Coil overs springs rate for a street?

Post by In XS 7 » Wed Jan 06, 2016 4:41 pm

Ghost wrote: I had 8" 225lb springs before and ran into coil bind as well as the upper mount & threaded sleeve bind.
I have a question: What means "Coil binds" and "Sleeves binds". Sorry about my poor English. :notworthy :cheers
Miguel.
89 XR4Ti Monique; Waking up a real "Night/Mare-Coor".
T5, NPR IC, PIMP ECU, Walbro 255, Dual piston BOV, Manual BC, 3" exhaust, One piece Aluminum drive-shaft, mc2 LSD, Boport 1.5 cam, Ported and polish head, big valves, 80# injectors, Bob's log, (soon HY35).

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Re: Coil overs springs rate for a street?

Post by GPz11 » Wed Jan 06, 2016 4:45 pm

Well, coil bind is when the spring is totally collapsed. Not sure what sleeve bind is.

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Re: Coil overs springs rate for a street?

Post by xr4x4ti » Thu Jan 07, 2016 2:08 pm

hEaT wrote:That's interesting...how tall are the stock springs at 97lb/in?

The stock springs are much larger in diameter which helps the situation out tremendously.

The solid height of the spring is nothing more then the diameter of the spring wire multiplied by the number of turns (coils). To make a spring softer (lower spring rate) you have to do one of three things:
-Increase the number of turns
-Decrease the wire diameter
-increase its diameter.

If you take a standard 2.5in coil over style spring and go from say 350lb/in to 225lb/in while keeping the same free length, you have two things giving you issues. The 225lb/in spring has more turns and thus a taller solid height and the spring will compress more both statically and dynamically.

The stock springs are much larger in diameter and don't have this issue. That is one of the drawbacks of the small diameter springs used on coil overs. Especially if you are like me and are trying to run really wide tires and you want the spring totally above the tire. I seriously thought about either making or buying 5.0in diameter spring adapter to be able to use a really short spring and still have plenty of travel.

Tim
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