UHMW Mark VIII LCA Spring Perches

DLF

Registered User
I'm starting to make spring perches for the Mark VIII LCA's.

The current aluminum version (that I recently put in my SC) has a few problems, in my opinion.

The height of the inner perch, at 1.6" is too short (shorter than the stock MN-12 LCA's), and renders the air bags I have installed useless.

They're heavy.

They raise the ride height.

My design will not have a tilt to the base, I don't see the need for it, and it raises the ride height unnecessarily.

They'll be made out of black UHMW (other colors may be available), with a drilled hole for air bags, and sell for $150 shipped (lower 48) per pair.

I've got one request so far, and the first 3 sets will be ready to ship in 1-2 weeks.

Any interest?
 
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I thought we needed these to raise the ride height to match the height that the stockers provide. Is that not the case?
 
I thought we needed these to raise the ride height to match the height that the stockers provide. Is that not the case?

They're needed to position the springs, and a 1/2" base is all that I believe is required to match the ride height. Additionally, the center of the perch is used as a base for air bags to push against.
 
Measurements

I just installed both the stock MN-12 and Mark VIII LCA's in one of my cars and took some measurements.

When both are at the same ride height, a couple of inches compressed, as measured at the lower knuckle pivot points......

The Mark VIII spring pockets are 10" from the frame rail, both inside and outside.

The Stock LCA's are 9" from the frame rail on the inside and 10" on the outside.

So there is a difference of about 1/2" (on average) between the spring pocket depths.
 
How can it be two different measurements on the inside and outside on the stock ones. Are they at a different angle then the stockers?
 
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Not to hurt sales because thats not what I want to do, but do you really need these spring perches to run Mark8 LCA's on our birds? I know the perches are for locating the spring in the LCA but even without then the spring cant move around inside the arms when the car is siting on them. My '92 in my signature has the mark8 LCA with cut stock SC springs without perches and I autox'ed the tar out of it to the tune of a championship last season without any problems.

Shane
Glynn Motorsports
 
My SC has the Mark VIII LCA's and aluminum spring perches and my rear sits lower (just a little) than the front. I was told it was because of the LCA's and perches. :confused:
 
How can it be two different measurements on the inside and outside on the stock ones. Are they at a different angle then the stockers?

The spring perch is, but the pivot point for the lower knuckle bolts was at the same height.
 
Not to hurt sales because thats not what I want to do, but do you really need these spring perches to run Mark8 LCA's on our birds? I know the perches are for locating the spring in the LCA but even without then the spring cant move around inside the arms when the car is siting on them. My '92 in my signature has the mark8 LCA with cut stock SC springs without perches and I autox'ed the tar out of it to the tune of a championship last season without any problems.

Shane
Glynn Motorsports

I'm sure that you can get away with it, but the airbag pocket in the Mark VIII LCA's is quite a bit bigger than the springs, and there's no inner perch for the aftermarket airbags that I, and others, use for drag racing.
 
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How much lighter is the UMHW ?

- Dan

I haven't had a chance yet to weigh the completed UHMW perches, as well as the aluminum perches, but I will.

UHMW floats in water if that gives you any idea, it's specific gravity is less than 1.
 
My SC has the Mark VIII LCA's and aluminum spring perches and my rear sits lower (just a little) than the front. I was told it was because of the LCA's and perches. :confused:

But does the rear sit higher or lower now than it did with the stock LCA's (not compared to the front, but before and after at the rear)?
 
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I'm interested in a set. FWIW the aluminum perches weigh 3.45 pounds each. I attacked my set with a drill press and shaved a pound of that. Also, depending on the exact alloy in question aluminum weighs about 2.8 times as much as high density UHMW, so judging by what Doug is saying of his design I would assume each new perch to weigh right around 1 pound each.

And black would be fine with me, but I really don't care so long as they're not pink or something.
 
My SC has the Mark VIII LCA's and aluminum spring perches and my rear sits lower (just a little) than the front. I was told it was because of the LCA's and perches. :confused:

Are you sure your springs were not cut? I believe they were due to the car sitting way too high in the back.

Shane, your application hasn't seen 1000 miles since it was installed. That it "works" in your application has no real reflection on how it would hold up on the street, subjected to all sorts of impacts, etc. If the spring were ground flat on the bottom I'd feel a little bit differently about letting the spring sit on the aluminum, but with the spring cup in the control arm being comparatively thin and the spring putting extreme pressure on it at it's unground/formed end, leaves me very uncomfortable.

I never plan to run airbags so I'm not worried about that. I just want a properly formed and fitting spring perch, that's all. Using plastic between the aluminum and steel gives me warm fuzzies too. :D
 
Pictures

Here are three pics.

The first is a poly spring isolator centered in the pocket.

The other two show how much movement there could be without a perch. :eek:

Not on my car :)
 

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I had mine with no insert for about 20-30k street miles. ;)

Damon were is the metal on metal contact you are talking about. There is a rubber isolator that separates the two. The spring once it is seated does not move around. The only reason for this upgrade that I can see is for correct ride height.
 
Rico,

I wouldnt be to sure about the side to side movement. It can happen. And without the spring being located or centered and only relying on the force of the spring itself...I think that exces movement may lead to premature wear of the poly isolators. WHen my tax refund check comes in I may just get me a set of these for a rainy day. I have teh aluminum ones but they do weight a bit and my car is now a bit higher in the rear
 
What a PITA!

Because UHMW is so resistant to abrasion, it heats up the tool bits, and as a result, it's very difficult, and time consuming, to machine. Then there's the fact that soooo much material needs to be removed from a 6" diameter rod to make a perch.

I'm sorry, but no one, other than the one person who's already paid, is going to get these from me for $150.

Expect me to offer these for closer to $175.

If no one is interested, I'll certainly understand.

Pics of a piece on the lathe, and a couple of pics of a prototype (bare and with a poly isolator).

Regards,
 

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Doug, I think many people would be interested in these perches if you only made them so as to locate the spring. I know I would buy a 2nd set that was made only an inch or so high if that would save on materials and machining costs.
 
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