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j king
09-09-2009, 08:47 PM
I have a motorcycle that sits too high for my short legs. Is there a way to shorten the rear mono shock spring and it still work properly? I thought about replacing it with a air shock off a different bike but I would think it would be tuff to find what would be heavy enough.

I do see how to take the shock apart and I know I could cu off 3/4 or so but the spring wount have a flat final wrap to support itself. Any ideas?

Thanks Jim

MTNGUN
09-09-2009, 09:04 PM
If you shorten the spring, the suspension will have less travel. But, at least your feet could reach the ground ?

Are there any aftermarket springs available ? (it's been decades since I was a biker, so I'm not up to speed on these things).

Any room for improvement by switching to a smaller or lower profile rear tire ?

Does the monoshock have any means of adjustment ? I remember installing conventional spring/shocks on a bike, that had adjustable spring preload.

gnm109
09-09-2009, 09:20 PM
If you cut the spring off with a nice long angle through the cut, you can use a torch near the end to cause the cut end to lay down and make a flat base again. I've done this on Harley front fork springs with good success.

The torch must be kept away from the rest of the spring. Use it only to flatten the end. In that way, it won't affect the load-bearing qualities of the spring

You should probably do this in small increments to make sure that you don't go too far. Probably about 3/4" as you say would be the maximum before you would start getting coil bound.


Good luck.

Falcon67
09-09-2009, 09:42 PM
Typically, if you torch a spring you take a chance on ruining it. The heat will kill that end of it. Auto springs are cut all the time to adjust - we use a cutoff wheel to keep the heat out of the metal.

Also remember that the law of diminishing returns applies to springs - the more you cut off (reduce the coils) the higher you make the spring rate and the less drop (and give) you get. If you want the same travel and the spring rate is correct for the bike, you have to either source another spring/shock combo that lowers the ride height and maintains the rate or move the attachment points.

flutedchamber
09-10-2009, 12:21 AM
There is a company called Dennis Kirk. They sell street and dirt bike parts and accessories. One of their catalogs or the other sells replacement springs for monoshocks. They also have a great tech department that is very helpful.

IIRC their website is www.denniskirk.com

Peter N
09-10-2009, 02:53 AM
The usual fix for this problem is to recut the seat foam so YOU actually sit lower on the bike.
Another fix - for a monoshock bike - is to make adjustable 'dog bones' for the monoshock linkage so that you can vary the ride height. This does alter the suspension geometry a little bit, but lowering the rear end (as in your case) would give you less rake and more trail at the front, making it a bit more stable, but slightly slower on tight turns.

Peter

gnm109
09-10-2009, 10:28 AM
The usual fix for this problem is to recut the seat foam so YOU actually sit lower on the bike.
Another fix - for a monoshock bike - is to make adjustable 'dog bones' for the monoshock linkage so that you can vary the ride height. This does alter the suspension geometry a little bit, but lowering the rear end (as in your case) would give you less rake and more trail at the front, making it a bit more stable, but slightly slower on tight turns.

Peter

That's an excellent suggestion since the original spiring could be maintained without any cutting or heating.

One complaint I have had about dirt bikes, even though I'm not riding them anymore, is that the modern ones have a very high seat height.

I'm aware that this is primarily because they have a lot of shock movement and ground clearance for obvious reasons, but for vertically-challenged people, it's a chore even to get on one.

EVguru
09-10-2009, 11:01 AM
I have a motorcycle that sits too high for my short legs. Is there a way to shorten the rear mono shock spring and it still work properly?

Find the owners' forum for your bike. There may be a factory lowering kit and if not there might be an aftermarket. People do go the other way and you might be able to pick one up. If you're having the seat thinned, then look at fitting a gel insert at the same time. Here in the UK, Hagon amoungst others will make custom monoshocks and offer lowering options for some bikes.

Being short of shank myself, 5'11", but taking a 30" inside legg, I just own bikes that fit. I could even get both feet down on the early series Morini Kanguro off-roaders.

j king
09-10-2009, 03:24 PM
Thanks for suggestions. Aftermarket shock can cost 500 to 900!!

The bike is a street bike.I like it alot and it rides great but I when I stand still I can only touch with the tips of my toes or slide off to one side. I have a high dollar heated seat on the bike now and wouldnt want to cut it down.I really dont think there is much room to cut it down.I would be sitting on the seat pan!

I should get rid of it and get a shorter bike but this is a great riding bike.


BTW,, its a ST1300 Honda.

I am fairly good at figuring things out but the way the shock is mounted I dont have any way of changing the mount style...

ftl
09-10-2009, 11:15 PM
Check out:

www.st-owners.com

or

www.st1100.org

These are very active ST groups that I used to be pretty active with (I have an ST1100). If there is any way to lower your ST somebody at ST-Owners will know how to do it.

EVguru
09-11-2009, 05:07 AM
Having done a little reading, I'd not want to mess with any of the suspension.

The Pan European range is quite highly reguarded as a touring mototcycle, but there do seem to have been repeated problems with high speed stability, especially when loaded. No single item had been identified as the problem, but weight distribution, tyre types and pressures, suspension settings, screen angle etc. have all been implicated (singly or in combination).

How about a set of stacked boots?

Peter.
09-11-2009, 12:36 PM
Usual way is to change the dogbones but it seems the ST has none to change - looks like the shock acts directly on the swingarm.

If the forked part un-screws off the bottom of the shock you could possibly re-make that part a little shorter, or turn some eccentric bushes to press into it perhaps? Depends on what you have for clearance right now.

j king
09-11-2009, 06:57 PM
Peter. That is kinda what I thinking also. May buy a used one and mess around.Thanks

firbikrhd1
09-11-2009, 07:44 PM
Shorter Springs will work or you can cut the one you have. Two problems (perhaps more), arise from this. First, the shock will bottom out internally unless you shorten the piston as well, eventually internally damaging the shock, second, in cutting off your stock spring the spring rate changes, it gets stiffer. I've seen this combination done on Harleys with fair result, but the ride is much stiffer. Shorter springs are usually progressively wound so proper spring rate will be maintained and require a proper length shock to match. I would think hard before doing this one if a replacement spring/shock assembly is expensive.

kf2qd
09-11-2009, 09:26 PM
Most monoshock setups have a pair of dogbones that connect between the swingarm and the shock toggle. Longer dogbones will lower the rear of the bike. If you have much of a shop you could make a new set. You just have to machine them in pairs.