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Rear Spring

Which rear spring should I test?


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TeeLew

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I've got a set of the kel-trac studs or more accurately all thread.

I don't trust them since there is no way to tighten them to the car.
They're a better steel than all-thread, by a good chunk. This about the same for all studs. Thread lock or even a dab of silicone does wonders. There's not much torque on the stud when loosening/tightening the nut.
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K4fxd

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They're a better steel than all-thread, by a good chunk.
Maybe he changed vendors but the set I have is just regular all thread. Even if hardened I would prefer a real stud like an ARP headstud.

Using something like red locktite wouldn't work unless you are comfortable with 4 inches of the stud hanging out in the air.

It takes an extra minuet to swap the bolts to the studs and back but I get a warm fuzzy feeling doing it this way.
 

bnightstar

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TeeLew

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That's real coilover on the rear though so 600 is more like 1200 at the OEM location.
Exactly, and we know that it's more common to run a stiff rear spring like that. I just don't like the rear of the car stiff and want to 'bracket' a range that works well for me. I suspect the 500 is going to be too soft, but it will be an interesting test, regardless.

The rear end subframe is back assembled and under the car. Now I have to get it all bolted into place. I've taken a couple big swings on this one. I hope it's not a disaster, lol!
 

bnightstar

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Exactly, and we know that it's more common to run a stiff rear spring like that. I just don't like the rear of the car stiff and want to 'bracket' a range that works well for me. I suspect the 500 is going to be too soft, but it will be an interesting test, regardless.

The rear end subframe is back assembled and under the car. Now I have to get it all bolted into place. I've taken a couple big swings on this one. I hope it's not a disaster, lol!
I consider everything bellow 800 provided you have a reasonable front spring too soft.

Spring rates should be based on what tires you run. As stickier tires require more spring which is why race cars on slicks have 1200 lbs springs or more.
 

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K4fxd

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I consider everything bellow 800 provided you have a reasonable front spring too soft.
I go by lap times. Have you tested with lighter springs?
 

bnightstar

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I go by lap times. Have you tested with lighter springs?
I have tested a lot of times with PP1 shocks and springs package I can assure you 515/800 is much much faster. For example I was doing 1:09.9 on Stock PZero's (5 years old) 255/275 with the Ohlins while I needed 275/35/19 140TW semi slicks to run a best time of 1:09.77 with the Stock PP1 suspension.

I have a best of 1:06.39 with 305/30/19 AR-1's. So yeah I could guarantee that first 515 front is much better than 163 lbs stock and that 800 is better 740 PP1 rates. Considering springs didn't changed locations with the Ohlins.
 
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TeeLew

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The project has been a bit of a slog. I guess I need to do a separate write up about it. I'll do that after I know if it works. Anyway, after all sorts of playing around today, I finally have everything where it's supposed to be and almost all together. I'll have first impressions tomorrow.

BNight -
I think conventional wisdom would agree that the Ohlins dampers and spring rates are miles above the Ford PP package. The point is that you haven't tried the *Ohlins* with diffferent rates on just one end. You've tried their entire package, which we know is really good.

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.

The 7" rear spring is the perfect length for easy spring changes on my setup. I've got my fingers crossed that ride height won't be too far off. I don't like the idea of the spring platform jack-screw excessively exposed. I'll probably make spring spacers for ride height tuning if I need.
 

K4fxd

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These are heavy pigs but you won't know till you try.

Schumacher's setup was miles away from Barrichello's
 

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I've been out of town too long. I think you are going to be way too soft. With out going to coil overs, I think 600-650 is about as soft as I would want to go. But I am looking forward to another datapoint.

The perk is, you get the wild opposite end of the spectrum, and can work your way back. I will be looking forward to your takeaways once you get the 500 tested out. What are you doing with your dampers? IIRC, you have 500 dampers, can they handle a 500 lb spring rate?
 

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TeeLew

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I've been out of town too long. I think you are going to be way too soft. With out going to coil overs, I think 600-650 is about as soft as I would want to go. But I am looking forward to another datapoint.

The perk is, you get the wild opposite end of the spectrum, and can work your way back. I will be looking forward to your takeaways once you get the 500 tested out. What are you doing with your dampers? IIRC, you have 500 dampers, can they handle a 500 lb spring rate?
I only have the Shelby Struts, not shocks. The rears are stock. It's kind of a lark. Let's see what we find.
 

WItoTX

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I only have the Shelby Struts, not shocks. The rears are stock. It's kind of a lark. Let's see what we find.
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.
 
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TeeLew

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Quick update, it's on the ground and I've been around the block. It's got a gear whine that's concerning me. The diff groans a little turning in a cul-de-sac, but it's fine. No real read on the springs, but it drives.
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