soft front forks

[old slider]

Hope this is the right place to post.
Many will know I have had a sidecar chassis and sub frame built for my little W650 by a very good sidecar man.

The chair suspension is awesome, something you would probably see more in Car racing, I love it.

My problem is after riding it a bit more aggressive than an old grandma the front forks dive way too easily causing the front guard to hit the sub frame which is only about 20mm in front of the original bike frame, also the nose of the chair chassis gets real close to touching the road surface on those right hand turns, so I am picking when the body is fitted and overhanging the front it may/will try to dig in.

Handles ok and I don't want to look at leading link until maybe I find a damaged W front end. So do I go to heavier oil?, spacers? change the springs? any thoughts.



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[OddDuck]

Just some thoughts...

Check what's actually in the forks - oil volume, existing spacers, air pressure if they're air assisted, compare this against parts diagrams and workshop manual.

Check the forums. Is fork dive a known W650 problem, and are there a lot of stories about the fix?

Make your own spacers, after getting the fork springs / spacers out and taking measurements.

Check for aftermarket parts availability - progressive springs might be available.

Just my $0.02

[AllanB]

Contact Robert Taylor for a new set of front fork springs for your set-up. Fresh oil (weight recommended by him) and you'll be a lot better off for a minor $ outlay.

Cool looking build there - keep us posted.


https://www.ohlins.com/distributor/k...ion-solutions/

[mossy1200]

Are the forks as low down on the triples as possible? I cant see very well in photo but they seem to be 20 odd mm above the top triple.

[old slider]

Contact Robert Taylor for a new set of front fork springs for your set-up. Fresh oil (weight recommended by him) and you'll be a lot better off for a minor $ outlay.

Cool looking build there - keep us posted.


https://www.ohlins.com/distributor/k...ion-solutions/

Cheers guys,

Thanks AllanB, yes the less $$ spent the happier the missus, cool I will update as things proceed, its slow going though, about 3 years to this stage .



Yes the Forks are as low as they can go Mossy1200, but thanks for the input.

[malcy25]

Springs.

Spacers are an ineffective band aid that just makes it feel stiffer and harsher through the first part of the stroke. When it overcomes this initial preload, you are still left with an inadequate spring....

[pete-blen]

sounds like stiffer springs are need..may get away with pre-load spacers.. worth a try..

Is there any ride hight/leveling adjustment on the sidecar wheel ?..
It looks level in the pics with out the weight of a body / passanger and other crap...
there could be as much as a 150kg change in load with & with out a passanger & gear etc..
so I imagine it will lean down to the left once the weigh is added.. that will change the bikes lean out...
Easyer to build it in now than later.... will make life easyer to set up...

Here is a ride hight adjuster on the ADV unit i'm buliding... can level the car
for what ever load is in it with out changeing the suspension setting.. just simply
turn a bolt to move the swing arm up or down....
The bike still leans in the corners...

[old slider]

sounds like stiffer springs are need..may get away with pre-load spacers.. worth a try..

Is there any ride hight/leveling adjustment on the sidecar wheel ?..
It looks level in the pics with out the weight of a body / passanger and other crap...
there could be as much as a 150kg change in load with & with out a passanger & gear etc..
so I imagine it will lean down to the left once the weigh is added.. that will change the bikes lean out...
Easyer to build it in now than later.... will make life easyer to set up...

Here is a ride hight adjuster on the ADV unit i'm buliding... can level the car
for what ever load is in it with out changeing the suspension setting.. just simply
turn a bolt to move the swing arm up or down....
The bike still leans in the corners...

That looks awesome Pete, as I understand it, the sidecar wheel is pretty much fixed, but looking at the suspension setup I see it has various holes, so maybe. (sadly I'm pretty much just a rider, rather than an engineer/mechanic) all adjustments are made from the four connection points to the bike. I will show Roger your set up. Once the body is finished He will adjust the plethora of settings that he has built into the chassis mounts.

[Voltaire]

Yes, the spring rate is the spring rate, all preload is doing is adjusting static sag.

Wider handlbars and a VW Beetle steering damper ( between the left fork lower and chair frame ) are also budget ideas for tele forks.

I rode around Europe with a BMW r75/5 Watsonian combination.Horrible to ride a sidecar set up for driving on left to driving

on right.

Make sure you get the toe in and bike lean right as it makes a difference.

[Hemi Makutu]

Yes, the spring rate is the spring rate, all preload is doing is adjusting static sag.

True - however, if the spacer is solid, it may displace some of the air.
If he is real budget-minded...
Can he add air pressure for extra springing - via fork-cap valves?
Or add a suitable-sized engine valve-spring as a 'spacer'?

[AllanB]

Around a couple hundred for front fork springs. Better than fuffing around with spacers on the limp stock ones.

[Voltaire]

True - however, if the spacer is solid, it may displace some of the air.
If he is real budget-minded...
Can he add air pressure for extra springing - via fork-cap valves?
Or add a suitable-sized engine valve-spring as a 'spacer'?

Air pressure of forks was a 70's gimmick, I think fitting valve springs on top is same era.
Air acts as a damper, if the springs are too soft replace them, not expensive.

[Hemi Makutu]

Air pressure of forks was a 70's gimmick, I think fitting valve springs on top is same era.
Air acts as a damper, if the springs are too soft replace them, not expensive.

Air as a spring yes, but it aint much of "a damper" - in suspension systems.

If you doubt the effect of air on forks V, try max allowable pressure on one of your so equipped `70s machines,
& then vacuum pump a -ve pressure & feel the difference..


& O.P. was looking for budget/cheapo solutions, wasn't he?

[Voltaire]

Air as a spring yes, but it aint much of "a damper" - in suspension systems.

If you doubt the effect of air on forks V, try max allowable pressure on one of your so equipped `70s machines,
& then vacuum pump a -ve pressure & feel the difference..


& O.P. was looking for budget/cheapo solutions, wasn't he?

I'm converting my 70's machines to adjustable rebound and compression one at a time.
Budget and cheap generally result in disappointment.
I meant spring not damper....but hey I was at work...

[old slider]

I'm converting my 70's machines to adjustable rebound and compression one at a time.
Budget and cheap generally result in disappointment.
I meant spring not damper....but hey I was at work...

Thanks guys, I am great full for all the advice, only want to do it once and done properly. Upgrading the fork springs by some one competent in suspension is my preferred option, I wont be surprised if all of the suspension will need tweaking.