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#455557 - 09/23/12 9:49 pm Front fork upgrade for a OIF Triumph?  
Joined: Jan 2012
Posts: 421
Pete Suchawreck Offline
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Pete Suchawreck  Offline
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Western NY
I'm looking to improve the performance of my front end. The frame is a '72 with the stock 35 mm forks. What period options work with the minimum amount of futzing?
What forks and triples swap the easiest?
I want to continue using the conical drum brake.
The end result of the the project is a scrambler.
Thanks all!

#455737 - 09/24/12 7:56 pm Re: Front fork upgrade for a OIF Triumph? [Re: ]  
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Pete Suchawreck Offline
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Pete Suchawreck  Offline
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Western NY
It's an option- also could put in the race tech cartridge emulators. What fork brace have you seen cheap?

#455777 - 09/25/12 1:26 am Re: Front fork upgrade for a OIF Triumph? [Re: Pete Suchawreck]  
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Mike Baker Offline
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Mike Baker  Offline
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Asheville, NC
OIF forks aren't 35mm, they are just a bit smaller. You'd have to bore the triple trees fo fit 35's

#455866 - 09/25/12 6:12 pm Re: Front fork upgrade for a OIF Triumph? [Re: Mike Baker]  
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Tri74x Offline
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XS 650 forks slide right into triumph clamps. You'd have some work to do to keep the conical hub though, and I can't say it's superior to the Triumph's...
If you'd want maybe some extra length as per a scrambler/trail bike, look for late 70's Honda XR/XL off road bikes. Street versions also in 35mm would be your CB's, and Suzuki GT's/GS's of the era as well. Just note axle placement (leading/trailing)when on the hunt as to not upset current steering geometry- unless of course, you want to.

#455918 - 09/26/12 12:20 am Re: Front fork upgrade for a OIF Triumph? [Re: Pete Suchawreck]  
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Mike Baker Offline
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Triumph OIF tubes according to my trusty caliper - 1.360" = 34.54mm
Honda cb750 tubes 1.377" = 34.97mm

#455946 - 09/26/12 3:13 am Re: Front fork upgrade for a OIF Triumph? [Re: Pete Suchawreck]  
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DMadigan Online content
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ca, us
The basic problem with the OIF forks is the damper. The slots in the side of the damper tube allow the oil to flow from the bottom of the stanchion up the tube and down through the damper head into the space between the damper tube and inner stanchion, at first. Then the slot opens above the stanchion seal plug allowing the oil to bypass the damper head so it is only the small restriction of the slot making any damping force.

As the slider extends, the volume between the damper head and stanchion seal plug decreases pushing the oil back into the tube and the restriction washer up against the damper head. Unfortunately, it is only after the slot is covered by the stanchion seal plug does the damper head do any good.

You need a new damper tube with only slots in the bottom and an adjustable damper head.

#455989 - 09/26/12 11:52 am Re: Front fork upgrade for a OIF Triumph? [Re: DMadigan]  
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Pete Suchawreck Offline
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Western NY
Thanks for the replies gents!
-"cheap"-The fork emulators cost about the same as fork braces I've seen.
(Is it correct the XS650 emulators work in the Triumph forks?)
-Nice visuals D! So welding up the slots(or new damping rods) and installing emulators should significantly improve the forks. I also understand progressive springs help a lot.
How many people run a fork brace too?
As an off road racer I've done a lot of suspension fettling.

Contrasting between my Buell Uly and my Husqvarna the Triumph forks are very spindly and flex a bit (I know apples and oranges). I wondered if there were period upgrades involving 38mm forks and triples that were relatively simple.

#455992 - 09/26/12 12:22 pm Re: Front fork upgrade for a OIF Triumph? [Re: Pete Suchawreck]  
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kommando Online content
kommando  Online Content


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(Is it correct the XS650 emulators work in the Triumph forks?)

Only seen them fitted to Pre OIF Triumph forks and Norton forks, as long as you can get a good seal on the sides they will work but the added friction with the seal causes it own problems where the emulator is moving up and down inside a tube.

#455999 - 09/26/12 1:36 pm Re: Front fork upgrade for a OIF Triumph? [Re: kommando]  
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Tri74x Offline
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They'll work but you got to make a bushing for the cartridge to sit on, which in turn will make the spring a bit longer. Could be a benefit, really. Late 70/early 80's RM/PE, KDX/KX, YZ/IT's, etc.. were 38mm if you want to go that route. Other important geometry of these I don't know- best to go to bone yard with a mic and a tape measure.
Agree- good information on the triumph tubes!

#456060 - 09/26/12 10:02 pm Re: Front fork upgrade for a OIF Triumph? [Re: Tri74x]  
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Pete Suchawreck Offline
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Western NY
I have a 85 KDX donor bike. Worth looking at for sure.
I'll research the emulators some more-is there somewhere either of you can send me for more info?
Thanks!

#459326 - 10/18/12 4:39 pm Re: Front fork upgrade for a OIF Triumph? [Re: Pete Suchawreck]  
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Webby Offline
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Webby  Offline
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Belgium
You could try the Landsdowne Damper kit. Cheaper than other options (around 300 USD). I know John has listed Triumph kits on his site but I've not heard any feedback for them. He's sold a lot of kits to Norton guys and they all seem very happy with the upgrade and the customer service.
Have a look here http://www.lansdowne-engineering.com/

Webby

#459902 - 10/21/12 11:38 pm Re: Front fork upgrade for a OIF Triumph? [Re: Webby]  
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Pete Suchawreck Offline
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Pete Suchawreck  Offline
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Western NY
thanks Webby I'll give it a look.

#485588 - 04/13/13 10:18 am Re: Front fork upgrade for a OIF Triumph? [Re: Pete Suchawreck]  
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British Ironwork Offline
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England
Glad I stumbled on this thread.
I need to drop the overall length on a set of '72 conical hub forks. Until I read this thread I was simply going to fit a 50 mm spacer above the rebound spring. Now it seems I have to ensure the oil can flow smoothly through and around such a spacer.
Do you think leaving extra clearance between the damper tube and the spacer, and then milling 4 slots of, say, 6 mm down the length would be sufficient?

Cheers
Brian

#485760 - 04/14/13 10:27 pm Re: Front fork upgrade for a OIF Triumph? [Re: British Ironwork]  
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Juan Offline
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Juan  Offline
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Puerto Rico USA
I`m glad that I looked at this thread also,I have a 1972 conical fork and would like to upgrade it. The landsdowne dampers are what I need. I sent him an email because I didn`t see anything for Triumphs,
Juan

Update: I received an answer from John Bould and he said,
I can provide a damper kit to suit a T120/140 conicial hub , cost is 345 inc postage to the USA
Lead time is approx 20 days.
Regards
John Lansdowne-Eng

Last edited by Juan; 04/15/13 12:42 pm.

Juan
1978 T140V Boneville
1969 T120R Boneville
1967 TR6R Tiger
2014 Triumph Thruxton
#486554 - 04/20/13 3:01 am Re: Front fork upgrade for a OIF Triumph? [Re: Juan]  
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Pete Suchawreck Offline
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Pete Suchawreck  Offline
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Western NY
Well, I went a different route because Triumph forks are not rebuildable (bushings.
I decided with a better set of forks combined with the emulators. I bought a set of Betors from a Can Am.
1-The triples are alloy lighter and they will look great polished
2-Better damping.
Emulators are plan B. Rickman on this site will sell me fork seals.
re the landsdowne- I bought the forks for $50, seals will be $20-30. I can add preloader slugs for my fabrication costs- and fork oil. I will have to get a steering stem bushing fabricated so the Triumph steering stem will fit the Betor triple clamps but I have friends smile



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