[mtbvfr]

Hi Folks,

I have an AMP B4 with an F4 fork.

I am only getting about an inch of travel.

If I put all my weight on the handlebars, I can just make horizontal the top parallel linkage of the fork. The bottom of the steerer tube doesn't come anywhere close to the rubber bumper which is located on top and at the front of the bottom parallel linkage. There is about another 1.25" inches of travel available between the bottom of the steerer tube and the rubber bumper.

If I put all my weight on the saddle, about 1 cm is exposed of the shaft of the rear shock.

I have no pre-load set at all in either the front or rear.

With one spring removed from the fork, there was about 1 cm more travel. With both springs removed I was able to compress the fork totally which indicates there is no blockage in the dampers.

The Springs for the fork are rated at 350 pounds and I am 130 pounds, what should I go for? Springs with a rating of 325 or 300 pounds? Less?

The spring I currently have for the rear shock is supposed to be the lowest rating at 400 pounds. What rating should I go for for the rear shock?

Besides Pohl, who can you recommend for making custom springs?

What are the specifications I should supply them with?

Would it be possible to find "off the shelf" springs that would be suitable?

Is titanium a viable option or are the weight savings not worth the extra cost?

Thanks in advance for your input, Michael
Cusco Travel Services
http://www.cusco-travel-services.com
Find us on Facebook - http://www.facebook.com/pages/Cusco-Travel-Services/121330787892316

 

[derby]

Dude, are you asking about custom springs for a 15 year old fork? Half of us here weren't even born then!

 

[joshdurston]

Got some pictures?

 

[mtbvfr]

Dude, are you asking about custom springs for a 15 year old fork? Half of us here weren't even born then!

Always someone spouting off to boost their own ego.

 

[mtbvfr]

Got some pictures?

You can see pictures at the following page.

http://community.bike198.com/topic/42-the-mountain-bike-setup-thread/page__st__20

 

[joshdurston]

I just pasted the link here, sweet vintage ride!

 

[derby]

Always someone spouting off to boost their own ego.

Ha! I gave your post a bounce with a little humor since no one had replied for over a day.

It worked. You're welcome!

 

[mtbvfr]

Ha! I gave your post a bounce with a little humor since no one had replied for over a day.

It worked. You're welcome!

Ok, if I had seen a smilie at the end of your post I may have caught on to your humourous intent. :thumbsup:

Thanks, Michael

 

[Birdman]

Have you contacted AMP for lower spring-rate springs? Even though they no longer make the B-4 and F-4, they may have leftover parts inventory.

FWIW, I had the same frame/fork and switched the rear shock to a Risse Genesis air/oil (1 on ebay right now, as a matter of fact). Since I weighed about 165-175lbs when I owned the bike, the stock front fork springs worked great for me.

Best of luck - JMJ

 

[BMJ]

Cool ass bike!
I had one of those forks in the day. Ate up alot of the trail with it. The main problem I had with it was the pivot bushings wore prematurly. Lots of abuse in a small area. Too bad their not still in the market.

Best-O-Luck!

 

[mtbvfr]

Have you contacted AMP for lower spring-rate springs? Even though they no longer make the B-4 and F-4, they may have leftover parts inventory.

FWIW, I had the same frame/fork and switched the rear shock to a Risse Genesis air/oil (1 on ebay right now, as a matter of fact). Since I weighed about 165-175lbs when I owned the bike, the stock front fork springs worked great for me.

Best of luck - JMJ

I already have the lowest rated springs available from AMP. I am hoping that custom coils will be much cheaper than going the Risse route which would only provide a solution for the rear.

What's the Ebay page? I couldn't find anything for Risse Genesis.

 

[mtbvfr]

Cool ass bike!
I had one of those forks in the day. Ate up alot of the trail with it. The main problem I had with it was the pivot bushings wore prematurly. Lots of abuse in a small area. Too bad their not still in the market.

Best-O-Luck!

I haven't had any problems with the bushings.

There is a company in Germany that produces a similar fork if you have the dough.

http://www.german-a.de/en/kilo.html

 

[DeeEight]

The Amp's are a low-leverage design thanks to the long shock stroke of the thrushaft shock design (its a 2" stroke and 3" travel). I'd try something like a 300 pound spring if you can find one in the right length. You might also change the shock fluid weights. The shell spindle hydraulic oil they called for is basically about a 10 weight. ATF fluid which was an approved alternative was about 8 wt. FinishLine and Golden Spectro have offered shock fluids down to 2.5wt. Lower weights of oils will flow faster/smoother under a lighter spring force.

 

[Birdman]

I already have the lowest rated springs available from AMP. I am hoping that custom coils will be much cheaper than going the Risse route which would only provide a solution for the rear.

What's the Ebay page? I couldn't find anything for Risse Genesis.

http://cgi.ebay.com/AMP-RESEARCH-RI...Cycling_Parts_Accessories&hash=item4aa2d464c7

Caveat - the Risse shock is a tad longer than the stock AMP coil-over, so you'll get an increase in BB height.

If you know the front spring wire diameter, OD, and free length, you might be able to find a similar off-the-shelf spring with a lower spring rate through McMaster-Carr or some other spring suppliers.

+1 for also going with a lighter weight shock oil after the switch to lighter springs. I did this on my wife's F-3XC fork and later her Marzocchi Xfly80 forks.

JMJ

 

[mtbvfr]

The Amp's are a low-leverage design thanks to the long shock stroke of the thrushaft shock design (its a 2" stroke and 3" travel). I'd try something like a 300 pound spring if you can find one in the right length. You might also change the shock fluid weights. The shell spindle hydraulic oil they called for is basically about a 10 weight. ATF fluid which was an approved alternative was about 8 wt. FinishLine and Golden Spectro have offered shock fluids down to 2.5wt. Lower weights of oils will flow faster/smoother under a lighter spring force.

What pound rate would you suggest for the springs on the Fork?

I put 5wt Motorcycle suspension fluid in all the dampers and the damper action seems fine. Of course, when I can get softer springs the oil weight may need to be changed slightly.