Fork tube diameter

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jseng1

jseng1

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I'm working on sizing for Turkite fork bushings and have measured two sets of fork tubes - one set is 1.357 the other 1.355

Other specs say 1.357 to 1.359" for a tube.

Any other accurate measured specs would be appreciated before I have a batch of these bushings made.

thanks

Jim
 
I have a pair of 7K mile OEM fork tubes 1 @ 1.358" and one @ 1.357"
Both measured at where the bushing slides (they're off the bike as I put new Franks on and they are covered by gaitors)

JD
 
jseng1 said:
I'm working on sizing for Turkite fork bushings and have measured two sets of fork tubes - one set is 1.357 the other 1.355

Other specs say 1.357 to 1.359" for a tube.

Any other accurate measured specs would be appreciated before I have a batch of these bushings made.

thanks

Jim
Click to expand...

Now you know why some parts are undersized and must be fit. Now if the complainers would understand that too.
 
Norton specs them differently in different manuals.

1970 and Up Workshop Manual printed in 1973:

Main tube O.D.: 1.3590/1.3575 in. (34.29 mm/34.467 mm)
Top bush fitted I.D.: 1.3595/1.3605 in. (34.53/34.48 mm)

1970-1973 and 1975 Workshop Manuals:

Main tube O.D.: 1.3589/1.3574
Tob Bush Fitted I.D.: 1.3595/1.3604

Ken
 
lcrken said:
Norton specs them differently in different manuals.

1970 and Up Workshop Manual printed in 1973:

Main tube O.D.: 1.3590/1.3575 in. (34.29 mm/34.467 mm)
Top bush fitted I.D.: 1.3595/1.3605 in. (34.53/34.48 mm)

1970-1973 and 1975 Workshop Manuals:

Main tube O.D.: 1.3589/1.3574
Tob Bush Fitted I.D.: 1.3595/1.3604

Ken
Click to expand...

ANd the difference is .0001 in the specs? It'll change more than that between breakfast and dinner just because of the heat.
 
I measured the tubes on my unmolested 850 Mk3. One is 1.355 and the other is 1.357. And they are not exactly round either. Both tubes on my 74- 850 measure about 1.360 but I doubt that they are OEM. Jim
 
comnoz said:
I measured the tubes on my unmolested 850 Mk3. One is 1.355 and the other is 1.357. And they are not exactly round either. Both tubes on my 74- 850 measure about 1.360 but I doubt that they are OEM. Jim
Click to expand...
Having been in "proper" Engineering for 45 years.i laugh at these quote sizes. Turners turn to .001 grinders .0001 the limits for grinding are NOT plus or minus two thou!

Somebody is taking the pee....its a good job cranks are not produced with stanchion plus/minus limits :lol: I have just received 4 pairs of stanchions from Velocette Ltd..they are all "crack on" but thats the diffo between British trades men and Indian fourteen year olds.
May God have Mercy on our Rebuilds :!: :!:
 
jseng1 said:
I'm working on sizing for Turkite fork bushings and have measured two sets of fork tubes - one set is 1.357 the other 1.355

Other specs say 1.357 to 1.359" for a tube.

Any other accurate measured specs would be appreciated before I have a batch of these bushings made.

thanks

Jim
Click to expand...
Jim,
Be carefull with the finnished bore size, i have made and sent Oilon bush's to customers...Few have complained that they are to tight, others To slack...I turn them to be two thou sliding fit. on my stock mandrill.but with tubes being "all bleedin" size's ..well its pot luck...oilite will yeald with a couple off stiff blows from a hide hammer...but plastic will not! plus the outer dia is important as the plastic bush's will contract if the slider bore is tight...i now insist on having the sliders and stanchions..otherwise its a nightmare :!: :!:
 
I bought a brand new set of forks tubes when I put my race bike together ( OK it was over 20 years ago) and ended up with a great big tankslapper in the second race.
On stripping the forks to find the problem I found the brand new fork tubes were 4 thou below the minimum wear limit quoted in the manual.
They are still on there but I have some bushes made to fit them.
 
john robert bould said:
comnoz said:
I measured the tubes on my unmolested 850 Mk3. One is 1.355 and the other is 1.357. And they are not exactly round either. Both tubes on my 74- 850 measure about 1.360 but I doubt that they are OEM. Jim
Click to expand...
Having been in "proper" Engineering for 45 years.i laugh at these quote sizes. Turners turn to .001 grinders .0001 the limits for grinding are NOT plus or minus two thou!

Somebody is taking the pee....its a good job cranks are not produced with stanchion plus/minus limits :lol: I have just received 4 pairs of stanchions from Velocette Ltd..they are all "crack on" but thats the diffo between British trades men and Indian fourteen year olds.
May God have Mercy on our Rebuilds :!: :!:
Click to expand...

How much did those Velo stanchions cost compared to the Norton ones?
 
Dave ...which Norton Stanchions? Ebay £38 or £100 for British made. They all look the same....well to an un-trained eye they do :shock: Ebay £38 one's are not Hard chromed in the correct sence...our local chromer puts on about ten thou then size's them...they will last out 10 pairs from Indochinese parts. cheapo stanchions have a Flash coat...microns deep. 2000 miles without gaters...thats your lot.
 
john robert bould said:
Dave ...which Norton Stanchions? Ebay £38 or £100 for British made. They all look the same....well to an un-trained eye they do :shock: Ebay £38 one's are not Hard chromed in the correct sence...our local chromer puts on about ten thou then size's them...they will last out 10 pairs from Indochinese parts. cheapo stanchions have a Flash coat...microns deep. 2000 miles without gaters...thats your lot.
Click to expand...

You still didn't say how much the Velos were...
 
Dave,
velocette is a manufacturing name, who make lots of spares for Nortons..the stanchions are long roadholder at £100 a pair. plus tax
 
john robert bould said:
Dave,
velocette is a manufacturing name, who make lots of spares for Nortons..the stanchions are long roadholder at £100 a pair. plus tax
Click to expand...

Sorry, the naming threw me.
 
I just got my (second set) stanchions from "Forking by Frank" . Spot on dimensionally at 1.359". My first set from them was 33 years ago.
Fork tube diameter
 
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