Dunc
Hey guys...just bought some second hand Protech shocks for my front wishbone conversion on a robinhood...My questions is....they have 6mm holes though
the rosejoints/eyelets....is this really big enough to support the weight of the car?
Dunc
I have 1/2" on my car and I wouldn't go smaller than that
Yeas...that was my thought...they are pretty much useless that small arnt they 
The joys of buying second hand stuff 
Dunc
Wow - that sounds small. Iwould check on previous application, if this was an owner modification I would upgrade to 12 mm, if original Protech I
would contact them to discuss size and new application.
Sounds like they were made for a mountain bike!!!!!!!!
LOL...No..my mountain bike uses 8mm bushes
Quarter inch is what I use on my hill climb single seater, plenty strong enough if you use NAS bolts (the mountings will rip off before the bolts
shear), but for the road I think 5/16 NAS is as small as I would go.
Phil
Just another thought, F1 cars don't use anything over 1/4 inch in their suspensions, sometimes smaller, and the dynamic and shock loads they
experience will far exceed anything you will see on a road car. With a road car you just need to build in a factor for corrosion and neglect!
Phil
im using 1/2" too
From rough calcs you're looking at about 5 tonnes to break a 12.9 grade 6mm bolt in double shear. So plenty man enough if you use a decent bolt
and keep an eye on it. 12mm is rediculous overkill - your chassis will be pulled to bits before one breaks. But that is what 'looks right'
to us untrained folks with only production cars to compare to. I'm using M12s though simply cos that's what are needed with my MK
brackets/bushes etc etc 
.
Liam
duncan, i got them originally off nick skidmore.
http://www.locostbuilders.co.uk/viewthread.php?tid=48012
I can guarantee that you will find a 6mm bolt up to the job. You just need to change the brackets, or weld over the existing holes and redrill to
6mm.
If you're not happy, send them back for a refund.
And P.S. - dont underestimate the requirements of mountain bike shocks! It's not uncommon to have rear suspension linkages with leverages in
the region of 5:1, and the shocks wearing 500lb springs. So the shock mountings in these cases are taking more load than in a typical car.
Liam
Remember any bolt loaded in shear is also subject to tensile load --- ie from the nut being tightened, also it is subject to torsional shear e when the nut is being slackened.
They are pretty nice shocks so would be a shame to see them go....As I have not actually fabricated the mounts accomodating any size bolt would be
fine...
It might be possible to take the rose joints appart and machine out the eyelets to 8mm......
Seriously though...will 6mm really take a road car with some abuse?......:0
Where can I get suitably solid bolts from?
The bores are actually 1/4" so don't get using a 6mm bolt or you will feck it up.
There are actually 1/2" bore joints in the shocks top and bottom and Goldline ones at that (the joints are worth more than the shocks) so all you
need to do is knock the ally inserts I made as bore reducers out and you will have a 1/2" hole.
8mm or 5/16 would be plenty and 1/4" NAS would do it, people are obsessed with huge bolts, they are not needed if used in the right manner.
[Edited on 10/11/06 by Nick Skidmore]
I have 5/16 on the back of my car with 2 ZX10 engines & gearboxes sitting on them, also 12 inch tyres & 274bhp, that transmits plenty of
ooomph thro' those bolts in torque/shear/push/pull rotational moments & anything else you can think of - I ain't broke one yet, but
I'll keep trying!
I've known the 3/8" bolts as fitted on the front of Caterhams to shear.....
quote:
Originally posted by Phil.J
Just another thought, F1 cars don't use anything over 1/4 inch in their suspensions, sometimes smaller, and the dynamic and shock loads they experience will far exceed anything you will see on a road car. With a road car you just need to build in a factor for corrosion and neglect!
Phil
quote:
And that's fine if you want to pay £25.00+ for every bolt in Titanium.
Thought this forum was Locost?
The important point is to specify the correct fastner and installation. As has been said a correctly installed 1/4" NAS bolt will be fine for a
light weight car.
But bear in mind that race car components are normally lifed and inspected.
John
And that's fine if you want to pay £25.00+ for every bolt in Titanium.
Thought this forum was Locost?
NAS bolts for this application are steel and would cost about a £1ea from me, so for what you get they are Locost.
Tip tops weighting twice the weight of the average kitcar will be hung on 1/2 or 12mm bolts.
These weight much more and will be over engineered to last the 150000 miles that the car will be expected to drive.
I would be nervous at 6mm but would happily work on 5/16 or 13mm providing a high spec bolt is used.