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Restoring Chassis - FU Tube woes, Suspension bracket questions...
edthedrummer - 27/2/14 at 10:21 PM

Hello all!!

I am currently in the process of rebuilding an old Locost. The said car has allegedly competed in hillclimbs in the past, but never been on the road.

The problem is, I think Stevie Wonder welded on the front brackets. Not one correctly aligns with its respective rear partner, so this weekend I plan on re-doing them. I have new brackets on order, and have made up a Jig to align everything correctly. Having searched for more information, it appears the FU tubes on the car are part of the problem, so these will be removed and re-made as part of the alignment process.

So on to my questions:

1) What is the correct way of finding the centreline of the chassis? I have so far measured the widest points of the main spaceframe, front and rear, and found the centre of that, then using fluorescent fishing line to give me something to measure from. Is this an accurate way?

2) Edit: Created a new topic in Running Gear Section for this question...

3) The front section, incorporating the LA tubes, seems to measure correctly. If however, I can't place the wishbone brackets where they need to go, is it acceptable to reposition the LA tubes further towards the centreline by a few mm?

Pictures available on request.

Many thanks,

A Confused Ed.

[Edited on 27/2/14 by edthedrummer]

brum_gustavo - 28/2/14 at 12:57 AM

quote:

1) What is the correct way of finding the centreline of the chassis? I have so far measured the widest points of the main spaceframe, front and rear, and found the centre of that, then using fluorescent fishing line to give me something to measure from. Is this an accurate way?



Yes, but only if you can be sure that the those tubes are 90 degrees with the real centerline. IŽd suggest you to put the chassis on a sheet of plywood, draw the base of the chassis on it, and use it to take measurements, and even use as a jig for future modifications, if necessary. There is no problem, I believe, in making modifications to the chassis, as long as all the structure is the same. My chassis uses Caterham dimensions (shorter cockpit, longer engine well) in an otherwise book chassis.
Cheers

Slimy38 - 28/2/14 at 08:44 AM

quote:
Originally posted by edthedrummer

3) The front section, incorporating the LA tubes, seems to measure correctly. If however, I can't place the wishbone brackets where they need to go, is it acceptable to reposition the LA tubes further towards the centreline by a few mm?



Personally I wouldn't move the tubes, they are meant to attach to the other tubes at the ends, and if you move them inward you're moving the stress points. To do it properly I think you'd also need to shorten LD, change the angles of F1/F2, and then that would mess up FU again.

Is it both LA brackets that are causing the issue? Can you move the rear brackets to compensate?

Not Anumber - 28/2/14 at 11:52 AM

Not wanting to sound negative but is it worth it against the cost of making or buying a replacement chassis. If the car has not been through the IVA there seems little benefit in sticking with the same chassis.
I would be concerned about the effects of removing and relocating the brackets as the extra heating and cooling could weaken the metal.