replacing my stock shocks

[Guest]

I want to replace my shocks 13.25 in with some 14.25 off a TRIUMPH Thruxton that my friend has laying around, I usually ride 2 up with my gf, and im a big guy 225, I've been bottoming out.

Is there anything I should be worries about, I know the geometry off the bike it gonna be off but how much difference im i gonna see. i use the bike to commute in San Francisco all city riding.

[bwringer]

Which bike?

A shaftie may not have the added swingarm travel ("droop") to accommodate shocks 1.25" longer, and the angle may be somewhat marginal for the u-joint.

Your problem is not that the shocks are too short; the springs are too soft. Suzuki has always set their bikes up for the cadre of anorexic ballerinas they use as test riders.

Shaft or chain, raising the rear that much will quicken the steering a bit, but as long as you've taken care of the fork springs (you HAVE installed better fork springs already, haven't you?) it shouldn't get twitchy. Still, it'll be quite different, so take care on your test ride.

[fer_gloko]

WOW forgot that part 1980 GS850G

[mrbill5491]

Your stock shocks were bad couple years after you got the bike and you have had them on for 35 years? Wow, Not sure the taller shocks are gonna be what you need. Me, I would stick to the stock length and get a good pair of aftermarket shocks with heavier/higher spring rates. This also kind'a tells me you probably should look into replacing the front fork springs as well. Your suspension is in need of some serious updating.

[fer_gloko]

Yes, Im going to be rebuilding my forks this week with progressive heavy duty springs.

The question is, if I do put the bigger shocks is that gonna affect the shaft drive? not engaging on the gear, since essentially the rear tire will have a longer travel?

Im not too worried about the geometry of the bike, but i don't want to ruin the shaft drive.

[Steve]

If you have not yet purchased the springs, don't get Progressive (brand) springs. Get Sonic fork springs, instead, and get the heaviest 1.1 spring rate.

Longer shocks WILL affect the angle of the u-joint, it will offset it a bit from its intended area of travel. You won't necessarily be getting any more wheel travel, it will just be riding a bit higher. Stiffer springs is what you want to look for.

If you want to ride a safe, predictable bike, you SHOULD worry about the geometry, and running the u-joint at the wrong angle can ruin it.

.

[Phred]

I agree on the Sonic springs. I put progressive springs on mine which was an improvement, but then rode another bike with sonic springs. Next time I will go for the Sonic springs.

[fer_gloko]

Thanks, im ordering Sonic Springs, what kind of fork oil should i get? Ive heard the heavier the fork oil, that will make it stiffer ride is accurate?

[theDoktor]

When you get your Sonic springs, they will have instructions on what weight fork oil to start with. You may have to go lighter or heavier on the oil weight. Contact Rich at Sonic Springs if you have any questions. He's a forum member and a wealth of great information.
Something else to keep in mind- the listed viscosity of fork oils varies from actual tested viscosity by varying amounts depending on the brand. Stick with one brand for consistency. For more information go to the Calsci website and educate yourself (or maybe put yourself to sleep...).

[Steve]

Ive heard the heavier the fork oil, that will make it stiffer ride is accurate?

To some degree, that is true. Fork oil only resists the motion of the wheel, it does not prevent it. Some guys will (mistakenly) put in heavier oil to keep the front end from diving when coming to a stop. That is a mistake because the front will still dive, but it will just do it slower. Springs are what it takes to keep the front from diving. With proper-strength springs, you can use a lighter oil, as all it has to do is keep the springs from bouncing.

Progressive Suspension recommends 15w oil for most of their applications. The previous owner of my Wing had the fork springs changed to Progressives and they installed the recommended 15w oil. I found that after an all-day ride, my wrists hurt. Tracked it down to having them get hammered with every little bump on the road, including expansion joints. Drained the 15w oil, installed 10w and can now do several all-day rides back-to-back with no problems. My wife's bike and both sons' bikes have Progressive fork springs. My 850 has Sonic springs. All of them have 10w fork oil, they all ride great, but I think mine is the best, with the Sonic springs.

Keep in mind theDoktor's advice, though, one company's 10w oil is not the same as the next company's 10w oil, so keep your purchases to one brand of oil. I don't have enough personal experience with different brands to be able to tell you that one brand is better than another, so just go with whatever you can get locally.

.

[bwringer]

I am an enormous galoot riding a GS850 at highly necessary velocities, and I use Sonic 1.1 springs up front with 10W fork oil. I usually use Lucas fork oil. Might as well support the local football stadium. My shocks are Progressive with extra-extra-heavy duty springs, but in the stock length.

Anyway, I honestly would not go with the 14.25" shocks. Stick with stock length or at most 1/2" longer.

Had to think about this a little more to remember some examples... I knew a guy working on a custom GS850, and he tried ZRX shocks, which are 14" to 14.25" depending on who you ask. In any case, they put the swingarm and u-joint at a ridiculous angle. He never got the bike running, which was probably for the best.

I know a few people have installed 13.5" shocks on GS850 or GS1000 (exact same frame) shafties and been generally happy with the slightly quickened steering. In one case, we had to grind off part of a tab on the frame that keeps the swingarm from dropping in order to fit the shocks.