G/S swingarm + driveshaft extension 50mm

[Padmei]

Originally Posted by Rucksta

I've tried a few different lenghts including shorter.
I'm back to stock length swingarm and wheelbase after puting the steering head rake back to stock.

This is where I'm at now. It's a setup I've been playing with for 5 years and will get it right one day.



The weight bias is slightly to the rear and the trail is long due to only 20mm offset on the triples.
I think I'd like 25mm offset but the straight line stability is everything a longer swing arm produced without as much reduction in turning ability.
I'd just like a lttle bit better turn and am prepared to sacrifice an equal or slightly greater amount of straight line stability to get it.
Maybe this year if I get a milling machine lathe combo for Christmas I'll have a crack at a new set of clamps.

When I think about doing another swing arm mod 60-75mm looks attractive but it's already hard to get my ageing legs over the seat even without a swag on so I probably won't bother given how happy I am with the current setup.

Here's what I found mucking around with longer swingarms.

Longer swingarms reduce shaft jacking improving traction under power over rough ground especialy rutted uphills.
Under power the longer swing arms steer better and more predictably once you cross it up but you have to push that bit harder on corner entrty to get the front to break loose.
If you're not a cross up style rider the long swing arm will take more power input on corner exit before it starts to break loose. (slower turn rate higher exit speed - complete more of your turn on entry usually at a lower entry speed can be a positive or a negative depending how you ride.)

There was a noticable gap between the two styles that I did not find away to get the transition smooth with extended swing arms.
I've come closer to the smooth transition since going back to stock but not as good as the seamless transition between tracking and sliding that the stock bike delivers. (maybe the 25mm triple clamp offset would improve that)

Long improves straight line stability especially on loose surfaces e.g. sand but the forward bias of the mass centre means the front buries more easily and a more agressive riding style is required to keep the front floating.

Long also improves comfort as the suspension just seems more progressive and the load carrying capability is improved as you don't have heaps of gear behind the rear axel even when fully loaded.

In tight going I noticed a reduced willingness to turn.
The increased ground clearance was partially or totally discounted by the longer wheelbase resulting in getting hung up on the same rocks and trees the improved stock setup.
Long also makes it harder to loft the front end.

On the sealed twisties long gave a tendancy to understeer or push in corners.
Without as much shaft jack effect I found it hard to hold the bike down under power to stop it running wide but power down on exit was great just like in the dirt.

Long also helps get you over the saggy arse look that all G/Ss have especially those with a stock rear end and an enhanced front end.

In the end you have to decide what you want from the bike as well as where and how you're going to ride.
If I was hauling luggage down red dirt roads more often than doing day rides and weekends along the East Coast Ranges I'd go the 100mm extension for sure.

Awesome stuff Rucksta. Thats the most comprehensive review of the extended swingarms I've read. Cheers.

Brotownboy - you suck

[ontic]

Originally Posted by Padmei

Awesome stuff Rucksta. Thats the most comprehensive review of the extended swingarms I've read. Cheers.

What he said^^

Nice one Rucksta. One day someone needs to trawl through all your posts and collate these pearls of wisdom together somehow.
I'm still not sure which way I'll go on this. It will either be stock swing arm with possibly a increased travel mod (like you wrote up in the past), or the 50mm extension kit from Paul Rooney.
For my luggage hauling and long distance traveling inclinations, from your write up, it looks like a swing arm extension might be the better option.

First off I think I've got to see how this front end rides.

For those of us with the Rdubb triple clamps we've got the same bmw offset at the triple clamps (38mm), however for those of us with the WP extreme 50mm forks in these triples, with the leading axle and the huge increase in the diameter of the forks (compared to the G/S forks), by my back of the napkin calculations (due to keeping the 38mm offset at the clamps and the 14(ish)mm increase in offset at the axle) we seem to have decreased our trail kinda significantly.
I'm not sure though, and I am not very good at understanding all this- Rdubb seems to have put a lot of thought and calculations into this back when he designed them- he was however looking at a 100mm swing arm extension and utilising a lot of extra front end travel and changing the whole angle of the frame thus rake...
it is a bit too complicated for me to theorize out and will no doubt just require riding and testing.

For this reason though I have also been working on a set of 24mm offest clamps (sourced from a WR/YZ bike with Kayaba USD forks) that I will sleeve down to fit my WP50mm forks and compare- from my calculations, before any other swing arm/fork height/travel changes, the 24mm offset at the triples combined with the WP50's should give me a very similar trail to a stock G/S.
We'll see.

[Rucksta]

Ontic .

Your napkin is a pretty good drafting tool but it may be time to flip it over to a clean page.

I think you'll find the changes to the axle lead aren't that great. (+14mm)
Axle lead is measured from the centreline of the forks to the centreline of the axle.
With the USDs the axle hangs off the skinny end of the fork unlike conventionals where it hangs off the fat end.

When I went USD I had less lead than on my conventional forks but I didn't feel the need to go 50mm

[ontic]

a fresh napkin page will require some new more accurite measurements.
I'll try to do that tonight after work.

As it was I did measure that 14mm (actually, looking at the 'napkin' it was 13mm) from the centreline of the fork to the center of the axle.
This is with the conventional 50mm white power monsters compared to the skinny little G/S ones. The 13mm (ish) was the difference between this measurement on both forks.
I'm not sure how the 4860 or 43mm WP USD forks (which were also intended to use these triple clamps) compare, from images on the net, like you say with the skinny end down the bottom they appear to do a bit better in this regard.

here's what I am dealing with.

[Rucksta]

Sorry Ontic.
I thought you were using USD.
The napkin rules

[BMBoy]

In regard to the 50mm extended swingarm...

It would appear the easy way would be the 50mm bolt in block onto the end of the swingarm

Rather than the cut and extend.

How do you then get around the clearance for a decent tyre?

I'm familiar with the 6mm spacer to move the wheel away from the swingarm shaft but you would still never
fit a E07 tyre in there. Off set wheel lacing the only way?

[SOLO LOBO]

Originally Posted by BMBoy

In regard to the 50mm extended swingarm...

It would appear the easy way would be the 50mm bolt in block onto the end of the swingarm

There are at least two companies that sell a 50mm extenstion that is bolt-on.

As to the larger tire, I believe that relacing with a larger offset is possible, a member here had two for sale a while ago.

His site is here:

http://www.desertpistons.com/4stroke...le/forsale.htm

[LoJack]

I remember seeing a thread or post of someone documenting a swing arm extension. They cut the drive shaft, bored out the cuts and welded in the extensions that plugged into the two halves, and then drilled and welded in pins through the plugged portions. Seemed a great way to do it, and have been looking for it, but haven't found it yet. Anyone remember it and know where it is?

Is there any difference in length between a standard LWB twin-shock swing arm and the G/S lengths?

Anyone know of a shop that will extend swing arms?

Just curious... thanks, Lojack

[rediRrakaD]

Originally Posted by LoJack

I remember seeing a thread or post of someone documenting a swing arm extension. They cut the drive shaft, bored out the cuts and welded in the extensions that plugged into the two halves, and then drilled and welded in pins through the plugged portions. Seemed a great way to do it, and have been looking for it, but haven't found it yet. Anyone remember it and know where it is?

Is there any difference in length between a standard LWB twin-shock swing arm and the G/S lengths?

Anyone know of a shop that will extend swing arms?

Just curious... thanks, Lojack

http://www.advrider.com/forums/showt...=forked+rubber
Mine was done that way...

[LoJack]

Originally Posted by rediRrakaD

http://www.advrider.com/forums/showt...=forked+rubber
Mine was done that way...

"O.K.
I'll explain the drive shaft lengthening.
Cut, bevel the edges, bore the ends, cut the extension 100mm, but it has "roller pin handles", bevel the external edges of the extension, bore the original ends, weld it all together (reason for bevels!!), drill perpendicular to the shaft through the pin handles/original bits, countersink holes, pin/weld, turn the whole thing to 3 thousands. Easy right??
Some things are better left to the WAY more experienced."

Yeah, that's exactly it, but I remember seeing "before" picks, too. Funny, I thought I looked through that thread a few days ago. I think the only additional thing that might be helpful is to shot peen the surface to reduce surface tension. Maybe that's over kill, though.

Can this guy handle a twin-shock swingarm? Still not sure if it's something I'd want to do yet. Or how long and extension.

[wirewrkr]

Originally Posted by LoJack

I remember seeing a thread or post of someone documenting a swing arm extension. They cut the drive shaft, bored out the cuts and welded in the extensions that plugged into the two halves, and then drilled and welded in pins through the plugged portions. Seemed a great way to do it, and have been looking for it, but haven't found it yet. Anyone remember it and know where it is?

Is there any difference in length between a standard LWB twin-shock swing arm and the G/S lengths?

Anyone know of a shop that will extend swing arms?

Just curious... thanks, Lojack

same part number

[Prutser]

There are a few ways of extending the drive shaft.

Extending the original mono arm shaft(welding). With the torsion damper.
Lots of people are afraid that the circlip will faill that holds the shaft together.(when doing a lot of off road)

In my bike I'm using the /5 or early /6 shaft with an extended clutch bell housing.
So there is no torsion damper anymore.

Personally I prefer the torsion damper. And I'm not to worried about the clip.
That clip would be a feasible road side repair.
What worries me more is the extra force on the damper in the gearbox not using the one on the drive shaft.
The broken gearbox might be a bigger challenge in exotic counties far from civilization.....!!!!

Would some of you like to share your opinions or experiences ??

Thanks..

[Airhead Wrangler]

Originally Posted by Prutser

Would some of you like to share your opinions or experiences ??

I just put my bike back together with a solid shaft (no damper) and was concerned about the same thing: putting too much stress on the cush damper in the trans which (pre-'85?) is a known weak point. I figure though that if HPN uses solid shafts on all their mono and double sided swingarmed bikes then it probably isn't that big of a problem. The greatest stresses to the driveline usually come on pavement anyway where traction is the highest. I haven't had a chance to ride mine yet, but I guess we'll see how it feels. The vague floaty feeling of the cush damped shaft really bothered me in situations with a lot of on and off the throttle. It was just very lurchy and springy feeling.

[LoJack]

Originally Posted by wirewrkr

same part number

Really? wouldn't have thought that. Thanks.

[Prutser]

Originally Posted by Airhead Wrangler

I just put my bike back together with a solid shaft (no damper) and was concerned about the same thing: putting too much stress on the cush damper in the trans which (pre-'85?) is a known weak point. I figure though that if HPN uses solid shafts on all their mono and double sided swingarmed bikes then it probably isn't that big of a problem. The greatest stresses to the driveline usually come on pavement anyway where traction is the highest. I haven't had a chance to ride mine yet, but I guess we'll see how it feels. The vague floaty feeling of the cush damped shaft really bothered me in situations with a lot of on and off the throttle. It was just very lurchy and springy feeling.

Thank you AW.
I hope it will last. I have seen the one in you're tread. Same as in my ST. Extended in a different way though.
Done about 14000 km(off road) now and still no damage.
I'm not sure if the stress is the worst on pavement. It might be a lot with acceleration and bad roads. But I think the stress on the cush damper is pretty bad driving over rocks, corrugations, potholes and other obstacles.
Hitting something solid with a spinning wheel ALL THE TIME !!!
It might even damp some of the jacking of the monolever ! (my impression is it does)

I'm building another with a damper in the drive shaft. Maybe I need to wait till that one is finished and compare them.