Fork Extensions

[VAL. H.]

Thinking of making my R80 outfit a little more off road capable.

Has anyone any in for or thoughts about fitting Fork Extensions?

I know the back end and side will need to go up too, but this is about the front just now.



Val.

 

[mikeyboy]

I wouldn’t fit them to a solo bike ,
An outfit would put even more load through them.
What forks/wheel is currently fitted?

 

[Mistacat]

I would be tempted to use leading link forks.
That way you can reduce the trail to 1/2" to 1" which would make it a lot easier to ride.
Any more trail as in stock motorcycle front end, you will get steering shake up to 30 mph and have to fight it around bends.
Someone with a lot more outfit experience will be along to advice you more, My advice is based on trike design which I understand is similar to outfit geometry.

 

[VAL. H.]

I wouldn’t fit them to a solo bike ,
An outfit would put even more load through them.
What forks/wheel is currently fitted?

Get what you mean, ie the join would be a weak point. Only looking at about a two to three inch extension, so join would be between the yokes.

I would be tempted to use leading link forks.
That way you can reduce the trail to 1/2" to 1" which would make it a lot easier to ride.
Any more trail as in stock motorcycle front end, you will get steering shake up to 30 mph and have to fight it around bends.
Someone with a lot more outfit experience will be along to advice you more, My advice is based on trike design which I understand is similar to outfit geometry.

Don't know why, but I'd completely forgotten about leading links. Finding them is a challenge if I remember, when looking for them 6-7 years ago. Could make (have made) a set I suppose. So the thought trail starts to swing west...........hmm!?


Val.

 

[mikeyboy]

What forks are currently fitted,
If standard airhead ones they will definitely flex with extensions as the top steel plate will just bend putting stress on the thin wall threaded section,
Bad!

 

[Mistacat]

Mike is right, slugs in the forks to extend them are a very bad idea.
If you want to stay with telescopic forks then use overlength stations with billet yokes, but you will need to use raked yokes to reduce the trail.
A lot easier to use leading link forks as you can alter the length of the link to alter the trail.

 

[mikeyboy]

Mike is right, slugs in the forks to extend them are a very bad idea.
If you want to stay with telescopic forks then use overlength stations with billet yokes, but you will need to use raked yokes to reduce the trail.
A lot easier to use leading link forks as you can alter the length of the link to alter the trail.

By the time you’ve bought billet yokes and oversized stanchions,price wise it’s got to be close to a set of leading links,
The end result with LL on an outfit will be far better than can be achieved with conv forks

 

[tuftywhite]

Get yourself some Earle's forks. Lots of people with outfits can't be wrong.

 

[Mistacat]

Cost of raked billet yokes and overlength stanchions is over £1k so a very good set of previously enjoyed leading links should be available for less.
I understand that BMW mainly used Earles leading link forks but any other make would do.
All depends on price and availability.

 

[VAL. H.]

Ok, Overwhelming advise against extensions.

My outfit is based on a 1989 80 RT (no fairing these days though) Mono. Built up for the winter treffens, by Keving from Motorworks. So is already quite rugged.
It still has the steel plate top yoke, but iirc I have a cast one in the garage somewhere, along with a matching pir of front callipers.

Think I'll look into leading links a bit more. Doing a google search brings up loads of different options, makes the mind boggle.

Getting the rear end a little higher will be the next thing. A longer shock is obvious (current standard one is way too soft anyway), but might make the swing arm angle a bit too steep I thought. Is the g/s swing arm the same as the RT mono, or longer? Maybe swap it for a paralever....

I only want to lift the outfit up about 2 inches, as it doesn't have a grounding problem anyway. Just to make it look a little more functional.

 

[mikeyboy]

AFAIK,
G/s and mono arms are the same length.
I have a spare one of these extensions if you are interested.

 

[VAL. H.]

AFAIK,
G/s and mono arms are the same length.
I have a spare one of these extensions if you are interested.

Interesting, I've seen this done before. Retaining the rod brake is a prefference over the cable of the paralever, much more posrtive feel.

What has been done to the drive shaft to extend it?

 

[mikeyboy]

The actual drive shaft has not been extended,
The splined hub that drives the bevel has been lengthened by 75mm

 

[Nin]

Interesting, I've seen this done before. Retaining the rod brake is a prefference over the cable of the paralever, much more posrtive feel.

I think that works if you don’t have very long rear suspension travel.

If you do, you’ll need to back off the adjustment loads, in which case a cable might be better. Alternatively, is there a hydraulic rear brake actuator out there?


Sent from my iPhone using Tapatalk Pro

 

[scooter paul]

What forks are currently fitted,
If standard airhead ones they will definitely flex with extensions as the top steel plate will just bend putting stress on the thin wall threaded section,
Bad!

Putting aside all the negative aspects of using extensions and bearing in mind I have an alloy top yoke where the stanchion goes through the yoke, not butting up against the underside, does anyone make a 50mm slug for a ST diameter fork leg?

 

[VAL. H.]

Been looking at the difference between the R and g/s swing arms. Looks like they are the same and it's just the shock mount that has been moved. Interestingly it appears the g/s shock is shorter than the R shock. Is that correct?

Might be just a case of getting a new shock mount welded on, or even a longer shock. Who makes shocks to order? Got to get a stiffer shock anyway, so maybe the better route.

 

[Cheney Triumph]

Have you considered giving these guys a ring for some advice http://www.waspmotorcycles.com/on the road.html whilst I have never had dealings with them, they do come highly recommended.

 

[mikeyboy]

Been looking at the difference between the R and g/s swing arms. Looks like they are the same and it's just the shock mount that has been moved. Interestingly it appears the g/s shock is shorter than the R shock. Is that correct?

Might be just a case of getting a new shock mount welded on, or even a longer shock. Who makes shocks to order? Got to get a stiffer shock anyway, so maybe the better route.

I think the g/ s shock is 315 mm (don’t hold me to this)
Because the shock is mounted further forwards on the swing arm ,the wheel travel is more for a shorter shock stroke.
Shock factory in France can make a bespoke shock for you at a very reasonable price,
If you wanted to spend a fair bit more contact BAZ at hyperpro

 

[VAL. H.]

I think the g/ s shock is 315 mm (don’t hold me to this)
Because the shock is mounted further forwards on the swing arm ,the wheel travel is more for a shorter shock stroke.
Shock factory in France can make a bespoke shock for you at a very reasonable price,
If you wanted to spend a fair bit more contact BAZ at hyperpro

I know the g/s shock is shorter than the R, but would I be right in saying the g/s shock needs to compress more, due to it being more verticle?

I'll checkout the Shock Factory. I have been emailing Falcon shocks. They rebuilt a para shock for me a few years back, did a great job.

Another thought re shock is, does the para shock have the same fittings? (It's going to be another week before I can get back into the garage to have a look the wifes bike). I believe they are longer than the R mono shock, so if the fittings are the same, I might have a spare hiding somewhere iirc and an uprated spring might do.


Edit.
Yes, Remember now. I lowered the wifes para gs, so that means I definately have a para shock hiding in the garage and a bit of google time tells me the para shock is 70mm longer than the RT mono shock, which will give plenty of lift, though hopfully not too much for the shaft, plus the fittings look similar. Goodie.

 

[VAL. H.]

Have you considered giving these guys a ring for some advice http://www.waspmotorcycles.com/on the road.html whilst I have never had dealings with them, they do come highly recommended.

I've been looking at their website and will have to talk to them, but I fear they will be out of my budget. But I do have some ideas that might work as a cheaper alternetive. Need to find out how to work out the extra trail I'll need.