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Discussion Starter · #1 ·
Are the threads on whitworth nuts and bolts different from standard or metric bolts?
The reason I'm asking is I'm putting new fork tubes on & the threads holding the clamps to the bottom of the tubes are a little chewed.
I've checked the bolts with the thread gauges laying around here and (if this makes any sense) they kind of sorta match up to 8mm x 1.0 but not exactly.
I wanted to use a tap to just clean up the threads in the forks alittle...but want to make sure I'm using the correct size.
Any help, as always, is appreciated.
Thanks
 

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Richie said:
Are the threads on whitworth nuts and bolts different from standard or metric bolts?
The reason I'm asking is I'm putting new fork tubes on & the threads holding the clamps to the bottom of the tubes are a little chewed.
I've checked the bolts with the thread gauges laying around here and (if this makes any sense) they kind of sorta match up to 8mm x 1.0 but not exactly.
I wanted to use a tap to just clean up the threads in the forks alittle...but want to make sure I'm using the correct size.
Any help, as always, is appreciated.
Thanks
Yes, up to a certain year, dependent on make. Different makes adjusted to a more regular thread pattern at different times. You can buy Whitworth thread kits, or you can retap the holes to newer standard threads (I did this to my 66, too use anodized allen screws).
 

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Yes, the threads are different. The Whitworth thread (or British Standard Whitworth) is its own system that dates back to 1841. I'm looking at the formula for cutting Whitworth threads and it is rediculous compared to S.A.E.

The angle between the sides of the thread in the axial plane is 65 degrees for Whitworth, 60 for American Standard. Also where the root and crest of an American Standard thread is flat, the Whitworth thread is radiused.

International Metric threads are similar to American Standard, except that the depth is greater. The crest is flat, but the root is usually radiused. Same angle between sides as American Standard, though.

Hope this helps. Don't know where you can find a tap, though.
 

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I had many damaged threaded holes for the cam/tranny/primmary covers on the basket case 65 Tri that I built a while back. I tried to find helicoils to no avail. Most nut/bolt shops just had that deer in the headlights stare. Once in a while an old timer yould know what I was asking for but still couldn't help. We've got European members, maybe they can help. I gave up and tapped all the case holes 1/4-20 and 5/16-18. It worked out good and they cleaned up good and have held up good.
 

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I know there are a few british car and bike shops stateside that carry Whitworth taps and dies. If you're gonna be dealing with Brits on a regular basis, get the set, then make you're own pieces. Whitworth bolts can get pricey. I see the tap and die sets on Ebay a lot.

I don't know what kind of time frame you're in, but I'm gonna have to get some whitworth cutters soon to rebuild my one BSA and the AJS (the other BSA is rebuilt standard thread, and the Triumph I luckily didn't need anything). We could probably work a deal for any connectors you need.
 

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Discussion Starter · #7 ·
Thanks for all the info...this is a huge help!
At the moment I am a little pressed for time because I'm kind of in the process of moving...so the bike has to be "rollable".

there's a guy down the street that works on old Jags so I'm going to run down at lunch and see if he has what I need to clean up these holes....but I've come to the realization that I have to invest in some whitworth tools.

Scratch, thanks for the links....I'll check them out when the boss man is gone (I'm in work) & I'll pm you about maybe setting something up?

Thanks again!
 
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