Triumphrat

Tumbleweed · 08-09-2005

Guys,

I've been thinking of changing the stock fork springs to something stiffer, and have some questions:

Can I do this with the fork legs in situ, meaning just taking off the handlebars and work from the top of the legs?

I've been reading the "sticky", but can't find the answer there. Oh, and any suggestion for types/brands of springs would be appreciated...!

There has been something written about improving the fork action simply by adding some washers on top of the stock spring, but how many/how thick?

thanks,

T'Weed

legend21 · 08-09-2005

If you remove the spring, then you will have to adjust the oil level..

However, it is recommanded to remove completly the fork tube..and change the oil... operation take 2 to 3 hours..

Personnaly I succeed to improve the fork just with replacement of the oil, and using Ã* higner viscosity (20 w).

Concerning the washer to preload the spring 1 to 2 cm seems a good start..

cafetbird · 08-09-2005

The length of the washer will depend on the weight of the rider.... so you'll need to experiment. This will increase preload and stiffen the front end up. You can also use a longer tube for this.

Race Tech and Progressive Suspension are the springs that most people use.

Keep in mind that changing your fork oil to a heavier weight slows down your suspension - which might be O.K. until you get into a particularly bumpy curve...

jimmyj900 · 08-09-2005

OK, you've got a few things to deal with here.

Preload adjustment (shims, washers, spacers) determine the initial compression rate of the spring but don't change the overall spring rate.

For preload, use a piece of Schedule 40 (thick walled) PVC pipe that fits snugly in the tube and with the forks installed and fully extended draw a pencil line on the tube. Cut the PVC on that line and you'll have about 3/4" of preload with the tube caps installed. You can increase this with washers later if you need more preload.

If you don't have adjustable damping then changing the oil to a higher viscosity will increase the damping rate of the system. I'm using 20-weight in preference to the stock 15-weight oil because it reduces the rebound and keeps the wheel on the road.

The stock springs are constant-rate so you might want to install Progressive Suspension 11-1144 front springs. The deal with those is that under small compressions the rate is pretty similar to stock but as the suspension compression increases the spring rate increases proportionately. Race Tech (and other) constant-rate springs are available, but I personally prefer the variable-rate PS springs.

Triumph specs the oil level with the springs removed and the tube fully compressed. I set the fork oil level to 120 mm from the top of the fork tube with the PS springs installed and the tubes fully extended.

As far as doing this in situ; I duuno. If you've got drain screws on the bottom of the forks then it's possible to pump out the old oil. If you don't have the drains you'll have to pull the tubes to dump the oil.

Don't even consider leaving the old oil there: the stuff probably looks like aluminum paint by now.

Jim

cafetbird · 08-09-2005

Quote:

On 2005-08-09 09:33, jimmyj900 wrote:

The stock springs are constant-rate so you might want to install Progressive Suspension 11-1144 front springs. Jim

FYI - The early T-Birds and Adventurers had progressive springs, and recommended 10 weight oil.... or at least my '96 did.

Scot

Tumbleweed · 08-10-2005

Thanks guys!

I would think it was possible to siphon out the old oil with the fork legs mounted....you know, using the pump I use to change gear- and differential oil on my cage. It's just a matter of using a longer tube...?

T'Weed

JWoodsie · 08-10-2005

Its probably better to take them out, and drain them completely. I have a habit of draining them overnight. Get all that shiny stuff out.