Short Top Link

[rapcom]

For a variety of good reasons which involve a Knight and a sidecar, I am investigating the short top link option. There is little definitive information about fitting, eccentric position, and their overall effect, so if anyone can offer information and advice about them, I would be grateful.
The short top link is not mentioned in KTB, not in the Riders Handbook, not in the Instruction Sheets, not in Richardson, and the only brief mention is in the Temple Press/BMS book.
In BMS it states that with a short top link one should leave the eccentics in the solo position, but one current sidecar rider uses his in the sidecar position, and a note in MPH 240 January 1969 from a sidecar rider also says he uses the sidecar position. Which should it be?
I have already discovered that I will have to remove the shroud on the damper to fit the short link.
I have found the following written data in various books:
Standard Link, Solo Eccentric 3.25" trail
Standard Link, Sidecar Eccentric 2.5" trail
Short Link, Solo Eccentric ??????
Short Link, Sidecar Eccentric 1.25" trail
Another query is that BMS states that standard links are 4" centre to centre, and short links are 3.25", but the short link I have is 3.625".
Any info on fitting, handling differences, or any other tips gratefully received....

 

[nobby]

I have oirdered one from the batch that will be produced by the spares company. I have never seen any literature about it, so I will be gratefull for some enlightment too...

cheers

 

[ET43]

There are a few references to short top links in Fourty Year On. I cannot see that a short link in the solo position would give less trail than Rapcon's last measurement. I would hazard a guess and say that the short link/solo position would give a trail of around 1.75", assuming that a 20 inch wheel was fitted. Smaller wheels steepen the steering head angle and reduce the trail. The more the trail is reduced, the more likely it is that one will require a hydraulic damper especially adapted for sidecar use as the self centering action of long trail is reduced.. Solo dampers are soon destroyed if your outfit has the shakes!!
I was commisioned to ride the pre prototype Wasp leading link outfit in 1975. It had around 1/4" of trail and if one passed wind, you changed direction. It was that bad. Wasp eventually arrived at a figure of 3/4" which all their forks use today. However, I must stress that this is a L/L fork where the pivot for the fork is at least 1" below the wheel spindle, similar to what the Earle Fork B.M.Ws' use. I am not qualified to say what the effect of using the last suggested arrangement would be even assuming that one has an outfit which fits all normal parameters for sidecar wheel lead, width of the outfit and toe in respecting the type and weight of chair fitted, but I guess that it would be lively to say the least! It helps the handling if the tyre is run at 20psi so as to absorb some of the road shocks, as a hard tyre will impart some wobble to the handlebars as it rides over bumps, etc.
Good Luck, ET43

 

[john998]

Hello,
Standard top link is 4", my home made one is 3.5". Have always used side-car setting on eccentric, this with 13" wheels, and latterly 15" wheels.
It shakes it's head on take off, as all outfits appear to do, but other wise it makes for a good handling stable outfit.

Regards John.

 

[deejay499]

Hi Dick.

I have a short top link on the Shadow outfit, sidecar eccentics and 19" wheel with sidecar tyre. This outfit does not shake its head even with only a small amout of damper on. I have also ordered one for the Prince outfit and we may both have to do a bit of modding to the fairings and damper. We can compare notes. I found that with small wheels previously, I had to use the eccentrics in the solo position as it went into negative trail with the short top link, and I can assure you it is pretty frightening, as Phil says.

 

[rapcom]

deejay499
What length of short top link is fitted on your Shadow ?
Anyone know what length the new VOC Spares Co short top links will be ?

 

[nobby]

Would it be still possible to ride the Vincent with the short top link solo? Any experiences on that please?

Cheers

 

[deejay499]

Hi Cornelis.

I have no experience of trying a solo with short top link, only presume it is not a good idea. Maybe changing back to solo eccentrics will be ok - hope someone has tried it and lets us know.

Dave

 

[rapcom]

Further meditation on the subject leads me to raise two more points.
1. On an enclosed D, the altered angle of the fork blades may mean re-aligning the headlamp, as the headcowl angle will be altered along with the blades.
2. Altering the eccentric from solo to sidecar trail shortens the springbox length. Fitting a short top link will increase the springbox length, thus altering the preload in the opposite direction to the eccentric movement, and perhaps the ride height of the front of the bike, and thus needing adjustment of the sidecar fittings.....
Barrel of bricks, anyone ?

 

[mercurycrest]

Further meditation on the subject leads me to raise two more points.
1. On an enclosed D, the altered angle of the fork blades may mean re-aligning the headlamp, as the headcowl angle will be altered along with the blades.
QUOTE]

I wish I had an enclosed D handy as I've been wondering all the same things. My usual solution to making a sidecar behave on a Vincent is to replace the handlebars with a set of "sportbike" bars (similar to, but longer than BMW /7 bars) and use the sidecar position for the forks. I tried Vincent sidecar bars and they didn't work very well for me. The only short link I've seen was on Bob Haines' outfit and he loved it. Can you even use "sportbike" bars on an enclosed D? Would the instrument panel even fit? I wrestled a BMW/7 RS100 around Australia for five weeks with lovely leading link forks, but standard RS bars (because that's all that would fit the fairing) and it sucked! Your only choice may be a short top link. I'd recomend 14" or 15" wheels too.
Cheers, John