Quote:
Originally Posted by FWB
i see scary things here on this thread......
1) you should definitely be using grade 8 bolts on you suspension. with that being said, the correct ones that is,,,,,,the point of shear should not be where any threads are, it should be on a shoulder, a spacer should be used to create a crush or pull on the bolt equal to the downward force.
2) stainless hardware, is the weakest.....look at strengths. you will kill yourself with stainless bolts on your suspension. if designing a suspension is something you have never done...please please please consult with someone who has,.
jus' sayin'
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Fully agree with your comments. NO shear on threads. Would you please explain further your comment "it should be on a shoulder, a spacer should be used to create a crush or pull on the bolt equal to the downward force."
This is how I'm understanding your advice above. If I'm seeing it wrong please comment.
Jag lower control arm has a cross-tube running through it front to back, through which a 5/8" shouldered shaft runs, on which the twin coil-over shocks perch with 3/8" nuts and fender style washers compressing it all together.
My shocks have Poly bushes with a tubular metal sleeve through the bushes. So starting at one end (say Front) of the assembly:
3/8" nut & 3/8" ID flat (fender type) washer about 1 1/8" OD, shock, 5/8" ID flat washer, Jag cross-tube, 5/8" flat washer, shock, flat washer & nut.
When the front & back 3/8" nuts are torqued down the washers will be compressed against the shoulders of the 5/8" shaft and compressing the poly to a point that the inner metal sleeves are in crush.
Jaguar engineers would have figured out the crush equal to the downward force. Original shocks had rubber bushed so getting the rubber to move out of the way to preload the sleeves would have been no problem.
As my shocks are not Jag and bushes are poly, I have to accept that the shock producer designed the shock perch sleeves to be the right length so when torqued down the Poly will yield and all is okay. So I have to figure out how to make my 5/8" shouldered shafts the correct length.
Is my understanding anywhere near sensible engineering?
Some time ago I replaced the rear shocks on my Jeep Wrangler and I was surprised to see that the upper bolts were only 3/8" or 7/16" diameter. So thinking that the Jeep experienced a lot more off road use and the bolts holding the shocks performed fine, I considered that 5/8" stainless on the Cobra should suffice. I don't have the smarts to calculate the Kinetic impact at these sheer points on my IRS, so I love hearing from guys like you that can figure this stuff out.
Whatever I end up using has to be custom made for my application. So all advice is appreciated so I don't have to have do-overs.
Thanks
Arthur
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