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Old 09-13-2018, 07:51 AM
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Changing to lightweight brake calipers?

In higher speeds when passing short, sharp bumps, it sometimes feels like the front wheels loose contact with the surface.

I have changed to aluminum rims, and those made a huge, positiv difference on the road handling from the wire wheels I had earlier.

What's the weight saving if I change the GM metric iron calipers to a pair of Wilwood direct relacement light weigth aluminum calipers?

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Old 09-13-2018, 10:46 AM
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You reduce weight an oz at a time. There is a bit but much other areas to look at first.

If this is independent move the brakes inboard. Less sprung weight.

Lots of weight can be lost by going with oval tubing and pressing material into a die to make a stiff brace around trangular shaped tubing forming say a lower arm.

Coil over shocks weigh less and take up less room. Generally.
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Old 09-13-2018, 11:28 AM
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This is an independent front suspension. I already have tubular A-arms with coilovers. I don't want to mess with the A-arms tubing.

It would also reduce the unsprung weight to turn the coilovers upside down, but do they work properly if I do so?
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Old 09-13-2018, 12:45 PM
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I would not mess with mounting them upside down. But you can use a cantilever linkage or mount them midway on a trailing arm to keep that weight towards the center.
Really more of an aerodynamic and packaging thing.


What are you working with?
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Old 09-13-2018, 02:31 PM
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Quote:
Originally Posted by staleg View Post
In higher speeds when passing short, sharp bumps, it sometimes feels like the front wheels loose contact with the surface.

I have changed to aluminum rims, and those made a huge, positiv difference on the road handling from the wire wheels I had earlier.

What's the weight saving if I change the GM metric iron calipers to a pair of Wilwood direct relacement light weigth aluminum calipers?
I'd get the shock valving right before getting all up into this.
Reducing the weight of the rim tells me the shocks are worn out or need different valving to control it.
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Old 09-14-2018, 05:48 AM
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Quote:
Originally Posted by johnsongrass1 View Post
I'd get the shock valving right before getting all up into this.
Reducing the weight of the rim tells me the shocks are worn out or need different valving to control it.
I would even say, not only the shocks but also the springs need to be spot-on first!
Especially as I see another thread of yours where you were worried about your springs being "too compressed" and switching to stiffer springs with fewer coils, in order to have more space between coils: wheels loosing contact with the ground typically sounds like your springs are too stiff...

Last edited by wave1957; 09-14-2018 at 05:57 AM.
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Old 09-24-2018, 12:59 AM
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I have not changed to stiffer spings with fewer coils.
I have changed to stiffer springs with the same amount coils.
On the old springs I had to move the adjustment nut very high up to achieve proper ride hight and correct suspension geometry with lower a-arms level with the ground. The suspension is a Fat Man kit.

The new springs looks very correct, as the correct ride height is acieved with a lot less adjustment on the coilovers, but still enough "spring stretch" left.
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Old 09-24-2018, 04:23 AM
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Quote:
Originally Posted by staleg View Post
I have not changed to stiffer spings with fewer coils.
I have changed to stiffer springs with the same amount coils.
On the old springs I had to move the adjustment nut very high up to achieve proper ride hight and correct suspension geometry with lower a-arms level with the ground. The suspension is a Fat Man kit.

The new springs looks very correct, as the correct ride height is acieved with a lot less adjustment on the coilovers, but still enough "spring stretch" left.
OK, my mistake, you did not go with fewer coils, but I still think the same way, you have moved to stiffer springs that "look very correct", but now, these springs are too stiff for the car, not responsive enough, and therefore, as you said in your first post, it seems like the wheels loose contact with the road. You are going to have to find springs better suited, and that can be difficult, trail and error... Some companies selling coilovers explain on their website how to pick the correct spring rate, but a problem you will find is that the roads and the way we drive are very different between the US and Europe. So, a good spring in the US may not work as well in Europe, not being adapted to traffic, road conditions...
How was the car behaving with the other springs, the ones looking wrong? This may help steer you in the right direction, too.
In theory, for good road holding, you want soft springs and stiff shocks: softer springs are more reactive and allow the wheels to better follow the road surface (the problem you have), while stiff shocks control better the spring movements.
Get the correct springs for your car before you touch anything else. Buying light-weight brake calipers will not make your springs more responsive when they are too stiff in the first place.

And inboard shocks are another can of worms!
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Old 09-24-2018, 01:10 PM
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Ok. I'll just wait for the summer to test it.
I have kept the old springs and can switch back, if necessary.
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Old 09-24-2018, 03:40 PM
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Fatman suspension video'se

brent (fatman) has some good videos and says the softest spring is best

google SEMA HIRA FATMAN FABRICATIONS
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Old 09-26-2018, 01:55 AM
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Thanks for your inputs.

QUA1 hompage recommends 500 lbs springs for Mustang II IFS on cars with front axle weight 1350-1525 lbs.
Recommended spring rates wary a lot between different brands.
QUA1 also lists 1400 lbs as an average front axle weight for 32-34 Ford, which is close to the 1430 lbs actual weight on my car (scroll down a bit on the enclosed link for this information).

The reason I think the 500 lbs springs "looks correct" is based measurents of the distance between each coil at free length compared to the same distance when the spring is mounted on the car.
The 475 lbs springs was compressed app 60%. the 500 lbs springs are compressed app 40% when the car is at correct ride heigth.

But I'm aware that live testing only, will give the final answers.
I also appreciate discussions like this as they reveals a lot of knowledge and different experiences!

https://www.qa1.net/tech/documents/S...le-Weights.pdf
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