Anti-roll bar setscrews

S

smudger

Member
To anyone who has replaced their front ARB for any reason.......
......I'm going to do the uprated ARB swap soon but would like to order 4 new setscrews for the retaining caps before I start. To save me taking one out to find out, are these threaded all the way up the shank to the head or partially threaded? If partial, how long is the unthreaded section? Thanks in advance for any info.
 
When I bought my sway bar - Mal Clark the instigator - gave me a handful of HT bolts that were threaded up the whole shank . He also said " Nip em up again after 100kms"
Gerald
 
They're 5/16 x 1 3/8 set bolts. I am sure they were threaded along the whole length, but more importantly they must be high tensile.

Richard
 
And more importantly, so you know you are getting the right hi-tensile bolts they need to be marked on the bolt head with lines radiating to the centre (so called "star" markings for imperial hi-tensile bolts) three "star" lines indicating "hi-tensile".

Metric bolts use a number stamp on the top of the bolt head ie 8.8 (hi-tensile metric bolt) just so you don't try to fit metric bolts to imperial threads.

http://www.boltmasters.com.au/webfiles/ ... _Chart.pdf

(The BM letters is the manufacturers name)

Apologies if this is common knowledge to you, but it helps for those who are unsure,
Regards,
Scott
 
westOz74P6B said:
And more importantly, so you know you are getting the right hi-tensile bolts they need to be marked on the bolt head with lines radiating to the centre (so called "star" markings for imperial hi-tensile bolts) three "star" lines indicating "hi-tensile".

Metric bolts use a number stamp on the top of the bolt head ie 8.8 (hi-tensile metric bolt) just so you don't try to fit metric bolts to imperial threads.

http://www.boltmasters.com.au/webfiles/ ... _Chart.pdf

(The BM letters is the manufacturers name)

Apologies if this is common knowledge to you, but it helps for those who are unsure,
Regards,
Scott
Click to expand...

Three lines indicate a Grade 5 fastener, which I'd call medium tensile. Six lines indicate Grade 8, which I would call high tensile.

Yours
Vern
 
Thanks for the info, not all of it was common knowledge to me so you always learn something. The bit I did know, the length, seems to be the problem. Plenty of suppliers stock 1 1/4" or 1 1/2" but 1 3/8" seems to be nearly extinct. Just waiting on one stockist to get back to me on whether his are HT or not but that does seem to be a rare size nowadays.
 
smudger said:
Thanks for the info, not all of it was common knowledge to me so you always learn something. The bit I did know, the length, seems to be the problem. Plenty of suppliers stock 1 1/4" or 1 1/2" but 1 3/8" seems to be nearly extinct. Just waiting on one stockist to get back to me on whether his are HT or not but that does seem to be a rare size nowadays.
Click to expand...

Always has been rare really. 30 years ago when I was buying bolts, stocked sizes generally were in 1/8 inch increments up to 1 inch, then 1/4 inch steps up to about 4 inches and then 1/2 inch after that. Of course, if you were buying thousands any length was available. The easiest thing is of course just file the extra 1/8 in off. But that exposes the end to rust.

Another thought is to find a supplier of AN (aircraft) hardware. Those bolts are available in "grip ranges" in 1/8 inch increments. The down side of a AN bolt, said from finding it, is that they are not threaded the entire length of the shaft and the amount of thread may not be long enough in this application.

Yours
Vern
 
The original bolts fitted (on my '74 and '76 P6B) for this purpose have three "star" lines with the manufacturer identifier being GKN and have 1/2" of shank and 7/8" of thread. Three of the bolts from the parts car were 1.3/8" long and one being 1.1/2" which indicates there should be enough thread there to take 1.1/2" long bolts (with a spring washer) I would prefer a bolt with some shank as set bolts (those with thread all the way to the hex head) are really for adjusting bolt type applications and as the arb clamp does not contact the arm completely, using bolts with shank offer a stronger option as per factory setup. The clamp itself is 5/8" thick at the bolt holes and as mentioned above longer bolts can always be cut shorter if the depth of thread in the pivot arm requires this and apply anti seize to prevent rusting.

I see what you mean Vern with the grade 5 bolt being medium tensile, I just commonly call a stronger bolt other than a plain grade as being hi-tensile, when in fact we are referring to a higher tensile strength bolt which is why the factory used a three star bolt of higher tensile strength for the arb clamp application, which the chart linked below gives the grade 5 as you refer to, which may be a better chart of reference than the first one I linked to.

http://www.lippincottsupply.com/bolt-nut_ident.pdf

Regards,
Scott
 
Well if there is enough room for 1.1/2" length screws then that would be a lot easier to be honest.

BTW, hello there Vern, we did correspond about 12 years ago now when I bought an original Series 1 hazard flasher switch and warning light from you. I still have it on the shelf, just got to find the car to put it in - no sense hurrying these things. All the best to you.
 
If all that can be got is the longer 1.1/2" bolts then still check that these will go in and clamp up and that they don't bottom out first in the threaded holes otherwise you will have to shorten them as Vern suggests. You may also want to get some new spring washers as well if the old ones have lost their "spring".
 
After fitting my 23mm sway bar I found I kept breaking grade five bolts (sounds like a gun firing) so drilled and tapped the top arms to take 3/8 ones. No issues since. I suspect part of the problem is that I removed the air con compressor but not the shim behind the spring so the clamps were always cockeyed as the left side sat higher.
 
Having checked with the mail order supplier of the 1.3/8" screws that I found and being assured that they were HT I ordered them. They have arrived and have no head marking lines of any sort. Just the letters ARB on one side of the head and the letter S on the other. Can't find any of these marks on any of the bolt head charts I've looked at. Are they just makers marks or are they HT marks of any sort?
 
Ok, have now discovered that an S mark should represent the same tensile strength as a metric 8.8 mark. So these screws should be the right level of high tensile strength for the ARB clamp bolts. This is the link to where they came from if anyone else needs them and if those who know better than me agree with the S mark being the right grade.

http://www.mgbits.com/contents/en-uk/p3960.html

They are intended for an application on older MG's - MGA, Y type etc or possibly even the Wolseley 4/44 - they just happen to be the only screws of that size advertised anywhere that I can find.
 
If your new bar has a larger than standard hex on it, you will need longer screws than standard to get the same thread depth.
 
Hi smudger, I've only been used to the star markings for hi tensile designation, but maybe the "S" is an older system to specify grade 5 hi tensile bolts as the below link in UK seems to say

https://www.namrick.co.uk/acatalog/Home ... ts_18.html

Another one but pic shows star markings, but length is 1.3/4"

http://www.carbuildersolutions.com/en/5 ... -nyloc-nut

This next one has them at 1.3/8" long, click on the 5/16UNF size

http://www.trfastenings.com/pages/Unifi ... agon+Bolts

Another but only 1.1/2" long

http://www.margnor.co.uk/bolts/8-8bolts/unf/5-16unf

Or grade 5 in zinc plated if you want to bling it up :LOL: :roll: but 1.1/2" long

http://www.westfieldfasteners.co.uk/BZP ... .3125.html

I would still prefer to use bolts with some shank as with set screws you are just transferring a weakness up to the bolt head where it will most likely fail, but in saying that I note some manufacturers don't differentiate between bolts with shank and set screws when testing giving the same failure load for both.
 
Hi Mike,
I have got the Classeparts ARB so I believe the hex is the same size as the original bar.

And hi also Scott,
Thanks for all the links, it does seem that S grade is equal to grade 5 or 8.8 HT. Grade R being the next one down. Can't argue with the logic about shank and thread but you can't get them - unless you go back to the original comment about filing down 1.1/2" bolts with say 1/2" of shank. This would do it but just seems a bit of a bodge to me although I would if there were no choice at all. Hopefully the ones I have found will do the job.

Cheers, Simon.
 
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