Author Topic: Fork 2 way damper drawing  (Read 9964 times)

Offline dpaddock

  • NC, USA
  • Valued Contributor
  • ****
  • Join Date: Jul 2006
  • Posts: 429
  • Karma: 5
Re: Fork 2 way damper drawing
« Reply #15 on: 29.07. 2010 00:04 »
OK, John; thanks.
BTW, I used threaded rod to ensure the valve was properly centered in the fork ID. Using a die on plain rod resulted in an off-axis thread, and my lathe needs to have its threading ability restored. Also BTW, I used 5/16 rod; seems to work fine.

David
David
'57 Spitfire


Online chaterlea25

  • Wise & Enlightened
  • *
  • Join Date: Jun 2009
  • Posts: 3376
  • Karma: 48
Re: Fork 2 way damper drawing
« Reply #16 on: 29.07. 2010 21:19 »
HI All
David, a trick or 2 you can use to keep the threads straight is
1) hold the rod in the lathe chuck and use the tailstock hollow spindle up against the diestock to keep it square, advancing the tailstock as you turn the chuck by hand
2) make up a dieholder which has a morse taper that suits your lathe tailstock *smile*

A lot of the time I screwcut the required thread finishing a tad oversize and then clean with the die.
This gives the dies a much easier life especially on stainless

I found a photo of the complete "Dow" fork setup

"Enjoy the ride"

Cheers
John O R
1961 Super Rocket
1963 RGS (ongoing)

Offline dpaddock

  • NC, USA
  • Valued Contributor
  • ****
  • Join Date: Jul 2006
  • Posts: 429
  • Karma: 5
Re: Fork 2 way damper drawing
« Reply #17 on: 30.07. 2010 15:08 »
Good tips, John; thanks.

David
David
'57 Spitfire


Offline bonny

  • Valued Contributor
  • ****
  • Join Date: May 2010
  • Posts: 262
  • Karma: 1
Re: Fork 2 way damper drawing
« Reply #18 on: 30.07. 2010 16:00 »
just to say thanks for the drawing chaterlea , i have some nice 316 stainless steel bar and will turn up a couple . any other nice mods for the a10 ?

Online muskrat

  • Global Moderator
  • Wise & Enlightened
  • **
  • Join Date: Jul 2009
  • Posts: 8511
  • Karma: 112
  • Lithgow NSW Oz
    • Shoalhaven Classic Motorcycle Club Inc
Re: Fork 2 way damper drawing
« Reply #19 on: 30.07. 2010 20:33 »
G'day John O R,
                          Just fitted 1st set to the cafe, with 15 weight oil it feels great in the shed pumping up and down. Will have to wait to road test as I still can't get long pants on after last weeks little slide down the road. I made mine from duralium (high tensile aluminium) 19" O/A. Cost $30 and 3 hours to make 3 sets, the balls came from an old ball race.
 Fix one thing, find another. When checking the fork oil height on the '51 (2 1/2" on cafe) I was horrified. 8" of white GOOP. It's been a few years, lots of wash's and many wet rides since I looked at them. Water must get in on top of the seal and slowly work it's way in. Must be time for new seals and a small hole in the holders just above the seal.
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
Muskys Plunger A7

Online chaterlea25

  • Wise & Enlightened
  • *
  • Join Date: Jun 2009
  • Posts: 3376
  • Karma: 48
Re: Fork 2 way damper drawing
« Reply #20 on: 31.07. 2010 00:11 »
Hi All,
bonny, 316 is very hard on taps and dies!!!
Yup, lots more trick bits on my bikes!! (search for head steady)

muskrat, I believe most bikes will suck some water down the seals, I have gotten sealy which have a wee lip on top as well, this helps keep out the water!
I change the fork oil every year or so (or when I think of it  *conf*)

Hope your hide is mending well!!

Cheers
John
1961 Super Rocket
1963 RGS (ongoing)

Offline bonny

  • Valued Contributor
  • ****
  • Join Date: May 2010
  • Posts: 262
  • Karma: 1
Re: Fork 2 way damper drawing
« Reply #21 on: 31.07. 2010 00:15 »
well i normally use the carbide tools in the lathe for cutting male threads and use taps for the female , and i have stacks of taps because we were supplied with them in my old job. so costs me nowt.

Online muskrat

  • Global Moderator
  • Wise & Enlightened
  • **
  • Join Date: Jul 2009
  • Posts: 8511
  • Karma: 112
  • Lithgow NSW Oz
    • Shoalhaven Classic Motorcycle Club Inc
Re: Fork 2 way damper drawing
« Reply #22 on: 31.07. 2010 08:23 »
Bonny, why add more weight when you don't have to. I also did away with the lock nut, just tapped and cut the threads to the right length and used loctite. Yes the alloy might wear faster but we would be talking many years.
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
Muskys Plunger A7

Offline bonny

  • Valued Contributor
  • ****
  • Join Date: May 2010
  • Posts: 262
  • Karma: 1
Re: Fork 2 way damper drawing
« Reply #23 on: 31.07. 2010 12:29 »
cos i simply don't have any on the shelf muskrat, i used to work as a fitter and turner for a company that made machinery for sewerage works all over the world , any stainless scrap was thrown into a basket under my bench and when full , dumped ! i started to feel sorry for all this stainless being dumped so decided to give it a good home ;)

Online muskrat

  • Global Moderator
  • Wise & Enlightened
  • **
  • Join Date: Jul 2009
  • Posts: 8511
  • Karma: 112
  • Lithgow NSW Oz
    • Shoalhaven Classic Motorcycle Club Inc
Re: Fork 2 way damper drawing
« Reply #24 on: 31.07. 2010 14:30 »
 *smile* No worries mate, I'm a alloyaddict. Less weight there, more weight here (pats tummy).
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
Muskys Plunger A7

Online chaterlea25

  • Wise & Enlightened
  • *
  • Join Date: Jun 2009
  • Posts: 3376
  • Karma: 48
Re: Fork 2 way damper drawing
« Reply #25 on: 01.08. 2010 00:22 »
Hi All,
I suppose I should have stated the valve bodies were/are made from alloy
I have seen a pattern set with alloy rods as well

Cheers
John O R
1961 Super Rocket
1963 RGS (ongoing)

Kees

  • Guest
Re: Fork 2 way damper drawing
« Reply #26 on: 04.08. 2010 09:58 »
Hello John,

I have one question, I have a B31 do y outhink it also fits on my bike?
The inner diameter of my front tube is about 1" and the diameter of valve is .90" so the is a lot of space between those parts.
I think this will give no demping at all, maybe the inner diameter of your front tube is smaller?

Kind regards,
Kees
The Netherlands

Online muskrat

  • Global Moderator
  • Wise & Enlightened
  • **
  • Join Date: Jul 2009
  • Posts: 8511
  • Karma: 112
  • Lithgow NSW Oz
    • Shoalhaven Classic Motorcycle Club Inc
Re: Fork 2 way damper drawing
« Reply #27 on: 04.08. 2010 10:34 »
G'day Kees, Welcome to the forum.
                                                       I don't think John O R will mind if I answer.The OD of the valve is 0.950", giving 25 thou" clearance all the way round. Your forks would be similar to the A's and should work. Just check the length of the rod so that the valve is in the oil with the forks fully extended. Also make sure the forks have the correct amount of oil in them.
I just made 3 sets for my '51 and '57 and a mates '56 Goldie, they all work a treat.
Cheers
How many Karma's can I give John for the one post?
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
Muskys Plunger A7

Online bsa-bill

  • Wise & Enlightened
  • *
  • Join Date: Mar 2006
  • Posts: 5565
  • Karma: 65
Re: Fork 2 way damper drawing
« Reply #28 on: 04.08. 2010 11:17 »
You've just fired up my grey matter Muskrat.
I'm guessing the oil level should remain the same with the double damper installed, so would that mean the oil capacity should be the stated capacity (213 cc) less the volume of the damper valve.
Or maybe it's not that critical
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Online chaterlea25

  • Wise & Enlightened
  • *
  • Join Date: Jun 2009
  • Posts: 3376
  • Karma: 48
Re: Fork 2 way damper drawing
« Reply #29 on: 04.08. 2010 11:20 »
Cheers Muskrat,
couldnt have put it better *smile*
"design" will work for  A, B and C models

One thing though The rod should not be too long or it will clash with the "spike" in the bottom slider on full compression of the forks *sad2*
I am sticking to the "Dow" length originally quoted and just add some more oil!!

BTY the damper makes a huge improvement to the early type forks that didnt have bleed holes in the fork stanchions
Cheers
John O R
1961 Super Rocket
1963 RGS (ongoing)