Race Harnesses and Wheel Studs Questions

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dantheman
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Race Harnesses and Wheel Studs Questions

Post by dantheman »

Right the buckets are in, but i sense that is the easy part

where on earth do you mount the race harnesses to? the ones i have came with bolts that go through a hole in the triangular brace at the end of the harness. the bolt has a metal (brass?) unthreaded tube on it that is removable and slides freely over the bolt.

they look like this: Harnesses

so where and how is best to mount them? do i need to drill holes somewhere, make threads in those holes and bolt the screws in? what are the tubes for? do i need to weld them in? are pressure plates needed? whats the best solution?


also i was changing the alloys on the car from the 18's they came with to 15's (ET38). i put the front left on first, went on as expected. when i took the left rear off it had 2 spacers on it, i removed them, put my new alloy on, and the stud was so long it protruded through the wheel nut forcing nut key out. the rear studs were over an inch longer than the front ones. is this normal/stock on MR2's or do you think someone has installed longer studs on the rears?

i bought spigot rings for the alloys, but because i needed to use one of the spacers to effectively shorten the studs the spigots cant be used. what exactly is the point of spigots, ive heard 2 arguements: to locate the wheel or to distribute the weight of the car from the hub over the alloy. is it ok that the wheel is only held on by the studs and not the hub?
Last edited by dantheman on Sat Jan 30, 2010 10:15 am, edited 1 time in total.
ashley
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Re: Race Harnesses and Wheel Studs Questions

Post by ashley »

I'm guessing the sliders go on the bolts and allow the harnesses to rotate on the mounting bolts once you've tightened everything up.

You can probably bolt straight into the standard belt mounting point on the sill below the door for one point.

Image

Then I drilled a hole through the floor near the centre of the car (where it looked strongest), you will need a spreader plate on the other side to bolt into and this does not have to be welded in (although it can be if you like):
Image

Then it depends on how much trim you are keeping, and whether you mind making holes in things! You can either put two mounting points through the sill bulkhead behind your seats, and again a spreader plate on the back of each:
Image

Or you could consider a harness bar, but this usually means removing the cubby-box between the seats...

Hope that helps some :thumleft:
dantheman
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Re: Race Harnesses and Wheel Studs Questions

Post by dantheman »

ye thats great thanks. i dont have any trim so i can follow that pretty well. so the spreader plates dont need welding in? thats good. what size do you make the spreader plates? is 2mm sheet steel is sufficient?
jonb-
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Re: Race Harnesses and Wheel Studs Questions

Post by jonb- »

You can buy spreader plates and eyes from demon tweaks pretty cheaply.
loudandproud205
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Re: Race Harnesses and Wheel Studs Questions

Post by loudandproud205 »

or be daft like me, get drunk and buy a ferrari 275 gtb rollcage and make it fit as they have harnesses attactments lol
Slarty
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Re: Race Harnesses and Wheel Studs Questions

Post by Slarty »

dantheman wrote:ye thats great thanks. i dont have any trim so i can follow that pretty well. so the spreader plates dont need welding in? thats good. what size do you make the spreader plates? is 2mm sheet steel is sufficient?


If you do make them yourself, make it from something like 5mm boiler plate. 2mm would be a little too thin for my liking, plus it wouldn't take a thread very well.

Unless you have access to boiler plate, taps, work bench etc just buy them, they're not overly expensive.
dantheman
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Re: Race Harnesses and Wheel Studs Questions

Post by dantheman »

having thought about im planning on cutting 4 ~A5 sized squares of 2 mm sheet steel, to be doubled up. i will find some nuts that fit the bolts i have, or get new nuts and bolts, weld the nuts to the sheet steel and bobs your uncle. 4mm sheet steel over that area should be sufficient and secure enough.

i dont wanna buy those items off demon tweeks as i need to get working on this asap and they are really basic items that arent hard to recreate.
ashley
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Re: Race Harnesses and Wheel Studs Questions

Post by ashley »

These are the ones I went for:
http://rallynuts.com/motorsport/Interio ... es_304.asp

They are either 2mm thick, 5.5cms square or 3mm thick, 6.5cms square:

Image
Image

Gives you an idea how big to aim for buddy :thumleft:
dantheman
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Re: Race Harnesses and Wheel Studs Questions

Post by dantheman »

wow thats quite a lot smaller than i expected. doesnt hurt to make the sheets of steel bigger though i guess
ashley
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Re: Race Harnesses and Wheel Studs Questions

Post by ashley »

TBH if you need them to be much bigger/ thicker to stop the bolts pulling through you are probably already dead from the forces involved :(

But- yes, I hear what you're saying :thumleft:
dantheman
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Location: NW London

Re: Race Harnesses and Wheel Studs Questions

Post by dantheman »

disaster...the harnesses i have are too long. on their shortest setting theres too much slack if they are mounted lever with the shoulders. as i understand it you cant mount them low down or they will crush the seat and break your back in an accident. if there any simple solutions? things ive thought of so far is to sew up the extra length, but i cant do that myself, or to mount low and have a bar welded to the firewall higher up that the harnesses wrap around. but neither seem satisfactory and i need a solution by friday evening....
ashley
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Re: Race Harnesses and Wheel Studs Questions

Post by ashley »

Nightmare ](*,)

Choices:

- Use a harness bar (as you said- a bar across the car behind your shoulders for the straps to run over).
- Get new harnesses
Rogue
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Re: Race Harnesses and Wheel Studs Questions

Post by Rogue »

If you've bought the harness in your link then you've got the wrong one anyway. You need the type with the hooks on the end otherwise you end up mounting the shoulder straps in shear.

For racing we always use a six point harness, mainly because it stops the buckle riding up when you tighten the shoulder straps. The cheapest one I'd recommend is the Schroth Clubman II-6:

http://www.demon-tweeks.co.uk/products/ ... SSP91152-0

If you definitely want to go four point then this one's reasonably priced:

http://www.demon-tweeks.co.uk/products/ ... MH540-5002
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