fork oil seal holders and sliders

[Rex]

Might be a bit cheaper to buy some paste if you can't find the stuff you have though?

[Richard Hinton]

Hi Guys, i have found a company who have a Tap and Die for the forks and oil seal holders in the UK. However the cost is expensive. but they have asked me if its really BSW. another question was is it the American version of Whit which has a finer cut. So i Don't know there was reference to a service sheet 711A in the forum which i will try and down load.

Many thanks Guys

[JulianS]

Below a copy of part of service sheet 711 showing the thread as 1 7/8 inch x 28 tpi Whit.

Also a copy of Parts Bulletin 30 from December 1955 showing the thread as 1 7/8 x 28 tpi CEI.

711 also shows an illustration of the bench die holder. I imaging in would be very easy to cross thread a fine pitch thfead of 1 7/8 inch diamter.

[limeyrob]

Curious that its 28 tpi not 26 as cycle. also that its Whitworth form (55) when CEI is (I believe) 60. 
Be interesting to see if there's any archive footage from the factory, they would be making these threads by the thousand. Can we tell from the thread run out whether they are die cut or turned?  I put all mine together a few weeks ago, with all the fettling and working that entails so I'm not keen to take them apart again.  I wouldn't dare touch these with a tap or die, far to easy to cross thread and with a sharp tap or die you won't feel it.  I used the seal holder tool, packed it on the stanchion to make sure it was in line and worked it slowly like that using the stanchion as a guide.
I avoided stainless as I find it more trouble than its worth where threads are concerned (as said above, it galls something horrible) and there seem to be some quite badly made aftermarket seal holders around that have the wrong metal thickness.

[Swarfcut]

 Reckon it has to be CEI. Cock-Up's and Errors must always be borne in mind even from trusted sources. It has to be a Typo. Part No for the die is the same, Whit thread is out of place in this fork slider application. Well done to Julian for finding this in the archives. No wonder some aftermarket ones don't fit, all made perfectly with the wrong thread?

 Swarfy.

[groily]

If this is just a clean-up job, maybe the answer is to find someone with a lathe that will take the bits (and has gearing for 28tpi, not rare) and then clean the parts up?
Starting with a 55° tool if that's Popular Wisdom Version 1. and if necessary running a 60° one, 'PopWis V 2.' afterwards? That maintains 'straight' and no excess removal of either metal. (I'd wind by hand as opposed to under power, to avoid possible catastrophe.)

A mega tap and mega die at that pitch are almost guaranteed to run off and bugger things up if the first turn is wonky. The seal holder doesn't matter much - but the slider??

Otherwise, a single-pointy hooky thingy on the internal threads as suggested already (with several beers to alleviate the boredom of microscopic progress by hand) and a needle file of tiny triangular section for the male threads?
This is what I've done with mullered threads on messed up alloy hubs and their steel annular (taper roller) bearing adjuster rings. Similar problem at typically 20tpi and inch and three-quarters-ish. With success (one soon forgets the extreme boredom).

[chaterlea25]

Hi All,
For repairs like these I find "thread chasers" invaluable
A search on ebay showed up these,  one of each will set you back about £20 total
Either scrape away by hand or use in a lathe, I set up a rest and use the same method as used on a wood lathe
Fit the pointed end with a file handle to avoid injury 
Careful use will give good results careless use will scrap the part

John

[BagONails]

We've not seen a photo yet of the parts in question but I recently cleaned up a very dubious fork leg (slider) for the A65. I had to weld lugs for stays to build them up then file back to the correct shape and file the bolt hole back to accept a bolt from a half round half closed condition. (someone had been hammering on these to presumably get the slider off the corroded stanchion) Same with the pinch bolt threads, requiring re tapping etc.  The fine threads for the seal holders looked terrible but after a good long soak in diesel and a very gentle wire brushing they've come up OK.  Finally refinished the bore with a brake hone and plenty more diesel as cutting fluid and rinsing medium.

If the threads have been mechanically damaged rather than just filled with rust and crud then yes thread chaser, thread file, sharp picky thing turning the slider by hand in a lathe if possible and just follow the thread until you come to the next obstruction and work on it until the thread form is restored or at least the seal holder will go past. Being a very fine thread a few 'gaps' where the male thread has crumbled away won't matter ...rinse and repeat!

Finally the new seal holders require to be sealed in the threads to the slider, I used a few turns of PTFE tape as this helps to prevent galling too.

[Joolstacho]

Surely these threads would have been cut on a lathe BITD?

[BagONails]

Surely these threads would have been cut on a lathe BITD?

Almost certainly cut on a special purpose machine to do the diameters on both ends and cut the threads using something like a Coventry Die box. Not single point thread cutting as you would on your home machine and not using a hand held die either!

[Richard Hinton]

Thanks all for info on this, a biker friend who has machine shop company is willing to have a look and see what he can do. So now i wait for the original holders to come back from chroming then take the lot to him.
The new stainless steel ones i will scrap them. I think people who make pattern stuff should find a bike and try fitting the bits to them before selling.

[Swarfcut]

 If those new holders were boughtn new, don't fit and you are not a happy fella, don't just junk them. The supplier needs to be made aware that his reputation can be more than just tarnished by the poor quality and lack of redress if no refund is forthcoming. You've bought in good faith, he needs to get it sorted. Ebay, PayPal and Credit Card chargebacks all offer some buyer protection, make it work for you.

 As a caution to others, a rough geographical location is all we need to avoid something similar.  Somewhere some fat *astard is enjoying a champagne lifestyle off the backs of folks like us. Spoil his day, use every mean trick in the book to get your smile back.

 Swarfy

[Rex]

Thanks all for info on this, a biker friend who has machine shop company is willing to have a look and see what he can do. So now i wait for the original holders to come back from chroming then take the lot to him.
The new stainless steel ones i will scrap them. I think people who make pattern stuff should find a bike and try fitting the bits to them before selling.

Scrap them? Really?
Let's hope the chromers masked the internal threads of your holders or you'll be back to the same problem of being unable to screw them on.
I don't know what your mate's going to be able to do machine shop wise now they've been chromed. How will he hold them without damage?

[limeyrob]

A previous owner of my A10 must have had access to cheap chrome plating so a lot of nuts and bolts are chromed.  I've had to buy a set of BSC taps and dies and re-cut every thread.

[berger]

when a chromed thread picks up in my opinion it's worse than a stainless steel one, i had this problem years ago with a bolt someone had put on a mates honda 500t. what a job to undo it