I need advice on this fork issue

crazydave58 · Aug 21, 2023

I acquired this Amp Research fork in near mint condition. Unfortunately the fork steering tube is 1/2 inch or so too short for the frame I wanted to use it on. Im wondering if I can cut/weld extend the tube or what my best options are. Any help is appreciated.

Captain Awesome · Aug 21, 2023

#1 - awesome fork. Jealous!
#2 - you can absolutely extend it out just make sure it’s sleeved inside the union for strength

Is it a 1.125 threaded model?

crazydave58 · Aug 21, 2023

Captain Awesome said:
#1 - awesome fork. Jealous!
#2 - you can absolutely extend it out just make sure it’s sleeved inside the union for strength

Is it a 1.125 threaded model?

Thanks for that info!..its a 1 inch threaded. 6.10 inch length...I may consider selling if someone wants it.

crazydave58 · Aug 21, 2023

could I use a threadless stem extender? Would that work?

Wildcat · Aug 21, 2023

Just a half inch? If the cone nut will thread on to the fork then there's a way. I have left off the cap nut and used the handlebar stem to secure the cone nut and washer. The stem needs to be all the way down to hold it in place.

GuitarlCarl · Aug 22, 2023

Depending on the frame clearance at the cups... You may be able to trim a quarter inch off, top and bottom, of the headtube. Maybe more at one and less of the other, like I said depends on the headtube, just a half inch total.

Son of Kradus · Aug 22, 2023

GuitarlCarl said:
Depending on the frame clearance at the cups... You may be able to trim a quarter inch off, top and bottom, of the headtube. Maybe more at one and less of the other, like I said depends on the headtube, just a half inch total.

thats a good idea, and would work,
The biggest problem I found with lengthening a fork is the steering tube has to be welded really good, I mean the weld has to be ground down so the fork will still fit inside the head tube! this means grinding away the weld which weakens it, so to fix this ,a really good welder will bevel out the two joins and weld right through into the middle, we talkin 1.4mm steel here maybe less, so its a very fine line,
the suggestion of the threadless stem is better!
if you do chuck on a threadless tube just make sure the weld is in the middle away from the thread and bottom bearing, should be good to go!

MattiThundrrr · Aug 23, 2023

crazydave58 said:
I may consider selling if someone wants it.

I am the guy you are looking for. I'll have to take a measurement or two when I get home, see if I can fit it in the bike I'm thinking about.

crazydave58 · Aug 23, 2023

MattiThundrrr said:
I am the guy you are looking for. I'll have to take a measurement or two when I get home, see if I can fit it in the bike I'm thinking about.

Ok...if I can't use it..u have first crack at it

curtisfox · Aug 23, 2023

Son of Kradus said:
thats a good idea, and would work,
The biggest problem I found with lengthening a fork is the steering tube has to be welded really good, I mean the weld has to be ground down so the fork will still fit inside the head tube! this means grinding away the weld which weakens it, so to fix this ,a really good welder will bevel out the two joins and weld right through into the middle, we talkin 1.4mm steel here maybe less, so its a very fine line,
the suggestion of the threadless stem is better!
if you do chuck on a threadless tube just make sure the weld is in the middle away from the thread and bottom bearing, should be good to go!

What makes it really strong is rosette welds above and below the seam, to the inner sleeve, actually strong then the seem weld itself........Curt

crazydave58 · Aug 23, 2023

I don't really want to chop and weld this fork at this point. I'm going to explore all other options first. I have acquired another frame that should fit, but I wanted to use this Ruff Lucky frame to complete this trail bike.. I really appreciate all the great advice and input

crazydave58 · Aug 23, 2023

Son of Kradus said:
thats a good idea, and would work,
The biggest problem I found with lengthening a fork is the steering tube has to be welded really good, I mean the weld has to be ground down so the fork will still fit inside the head tube! this means grinding away the weld which weakens it, so to fix this ,a really good welder will bevel out the two joins and weld right through into the middle, we talkin 1.4mm steel here maybe less, so its a very fine line,
the suggestion of the threadless stem is better!
if you do chuck on a threadless tube just make sure the weld is in the middle away from the thread and bottom bearing, should be good to go!

Trimming the head tube is somehing I have considered. Thank you

crazydave58 · Sep 3, 2023

I took the amp research fork to a welder and he told me he could extend the stem for me but of course it would be costly. For now I picked up this steel GT transit bike for $60 a couple weeks ago. I think its from the 90s. I liked the style of the frame and it had a shorter head tube that would fit my amp research suspension fork. The steering stem and the seatpost were completely seized so that took some time to resolve. The frame is a tad smaller than my Ruff frame but I think it should be ok for my purpose. I put it together and I am testing it out . The fork has a nice feel to it. If I keep this setup I will disassemble and paint the frame and work on all the fit and finish details.