Aluminum Cradle

[aaron88]

Preview

[can machine]

Any idea of what the weight savings will be?

[dguy]

Pre-88 by the shape, I think?

[aaron88]

Universal actually, since the rear control arm and possibly(not sure yet) knuckle are custom.

I'm not sure what the weight savings will be because I didn't weigh the stock components. I haven't actually done any weight calculations.  All my calculations have been for strength and corrosion.  I know what the cradle weighs but I don't know what anything else weighs.

Basically I do custom so I can change anything to match whatever the customer wants.  But in this economy and the tight wallets of most Fiero owners I don't expect to sell many.

I'm going to make a second one for myself that will be considerably lighter though.  Without the exhaust humps and for Northstar/F23 combo.

Aaron

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[aaron88]

Why is it that when you think you have all the kinks worked out something comes up and bites you in the but.

It turns out that fixing the geometry is the really easy part.  Figuring out how to do it cheep is really hard.  I'm having trouble with the stiffness of the knuckle and can't seem to figure it out without replacing the knuckle.  Needless to say a custom knuckle isn't exactly a cheep solution.

Does anyone know of a rear knuckle in existence similar to the 88 rear?

Aaron

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[falcon_ca]

Aaron

Did you read this :

http://www.fiero.nl/forum/Forum2/HTML/120882.html

[aaron88]

I saw that, but Heim joints are not street legal, so I'm trying to use ball joints.  Also the 88 knuckle mounting location is a bit high and I will not be using a trailing link.  All the geometry just screams custom knuckle to me.

I also can't expect everyone to just go out a acquire 88 suspension c/w coil over kit.  Not to mention that the 88 rear suspension is, itself way out of date and doesn't track true anyway.

I'm trying to figure this out without making too much stuff to try and keep some of the cost down or I can expect to never sell a kit.

Aaron

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[can machine]

Is the aluminum cradle going to be street legal? I'm not sure what kind of inspection/certification you would need to use it legally. Have you looked into that? Or can you just slap a "For off road use only" sticker on it to cover yourself?

[aaron88]

The whole thing is kind of a grey area.  There are so many kits and hot rods out there they can't deny something because it was fabricated.  All it has to do is pass the safety inspection.  Lots of aluminum cars out there so I don't see why it wouldn't pass.

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[can machine]

It seems it is a very grey area. I guess it would depend on who does the safety inspection. If they went by the book the mechanic I think would have to fail it since it is a non OEM part. There are lots of cars with aluminum cradles but they have passed certain design/fabrication standards. You or the owner of the vehicle could be liable if something failed. With that being said the one you are designing could be stronger and more durable that the original one. It's kinda a tough call since this is such a integeral part of the car.

[aaron88]

It's a bit more straight forward than that.  There are tons of kits available that have moving parts.  That is where the grey area is.  Moving parts (only the ones safety related) and safety equipment need to be tested.  Non moving parts need nothing passed a safety check.  That's why I'm using actual motor/trans mounts, control arm mounts and ball joints.  Ball joints are from chev 1/2 ton.

My knuckles on the other hand are a toss up.  Even though those west end boys have been selling welded front knuckles and all, they also advertise them as auto-cross (ie. off road use).  One of the reasons I'm looking for something a little more "OE".  That and to keep the cost down.  I'm sure if I did billet aluminum nobody would give it a second thought.

My cradle is more rigid than stock, and stronger.  Especially stronger that all those rusted falling apart cradles.

BTW: I also can make steel cradles using the same fixture so if there is a problem I can pop off a steel unit in half the time.

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[can machine]

Really? I'm really surprised if what you are saying is true, and I'm not doubting that you have researched this. I would of thought that a piece like the cradle would have to be inspected by an engineer and have some sort of testing done on the welds to ensure it would not fail under normal wear and tear. Interesting and scary to think of what people could by and use on there vehicles.

[aaron88]

Control arms.  No bump steer.

[lsixtyseven]

Looking good, I like.   

[dguy]

Are those ball joints at the control arm/cradle connection?