Landracing Forum
Tech Information => Technical Discussion => Topic started by: neandethal on December 27, 2019, 12:35:37 PM
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Hi Folks,
Don't suppose there is anyone on here who saw the Buddfab team race and could share with me how they solved the gear shift issues. Have looked into pneumatics and it looks too hard, trying direct rod but the "All breaches of the firewall must be above halfway up the wall" makes it all difficult to ratio the movement, and cable is so fussy about absolute correct adjustment.
Those boys seemed to get most things pretty darn good, so wondered what their solution was. No photos i can find show a system.
Thanks for any help, cheers Ian
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Don't know what they did, but electric, pneumatic or morse cable are all things I've done or seen. My preference is pneumatic because we up and down shift, but these days electric might be easier. Both of those don't really require a penetration other than an electrical connector.
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I don't know what BuddFab did either. My shifting option on a custom bike I am building uses the Pingel electric shift. It shifts up and down with two buttons, like an F1 car. It enables you to shift manually or with the push button. The kit has options for shift-cut, etc. Not cheap at $1000 new but it is used in a lot of race bikes.
Don
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... "All breaches of the firewall must be above halfway up the wall"...
To what vehicle category does that rule pertain?
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AMA or FIM is my guess Jack.... no worries it's not a car rule :cheers:
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its SCTA streamliner class.
Thanks for responses, the Pingel set up is too rich for my garage build, looked into pneumatics but have decided to try cable to start with cheapest and simple to understand. Thanks for views.
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Cables will work, we had one on our lakester the first year we ran. It shifted but the shifts were some what vague and slow so we (Duke) changed over to a direct connection with a polished 1/2 inch chrome moly rod and oil lite bearings to guide the shaft, longer and stiffer shift handle and now it works much better than the cable but not a good as Stainless's air shifter.
When using a cable be sure to constrain the cable shield as much as possible especially in areas that may be loops. The more you constrain the cable the better it works and feels.
Rex
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Rex;
I am switching over to 3/4" ground & polished RC60 shaft running in Thomson linear ball bearings. A 1/2" shaft might be OK if it is short. My layout is mid-engine so it needs a stiffer shift mechanism due to its length.
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Rule 7.H.1 ... why is a m?cycle streamliner expected to have fuel sloshing about on the floor?
Ian
When I had the Europa I used Morse push / pull cables (teflex 33c) from Hindle controls (UK). Other suppliers exist, often in the marine space. They have 5mm ball threaded ends and I used small ball joints to attach to the levers.
That car had a 5 speed H gate; I used two cables (MR2 shifter is a brilliant option in the cockpit): one cable for across the gate and one forward and back. I assume on a bike box you only need one - those cables were really long but the shift was as good or better than any modern.
I had no alignment issues (need good outer cable location at front and rear). I just snaked the cables through the backbone chassis and around the motor to the very rear; any additional P clip attachments were to stop them fouling on things, not to locate them.
For the Lakester I am using tube with short lengths of 12mm ground silver steel rod attached for passing through rod ends where the run changes direction as that allows some misalignment, and milspec UJs.
John
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cable option it is, will make a mock up with bowden cable, and probably get Venhill to make the real thing with nice slippery liners in place, cheers lads.
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I use a Morse push/pull cable to actuate my sequential shifter. It works well but normal stiction in the cable requires use of a heavier spring to bring the barrel shifter back to neutral for the next gear selection. Haven?t ruled out air or electric but trying to sort out other more pressing gremlins first.
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cable option it is, will make a mock up with bowden cable, and probably get Venhill to make the real thing with nice slippery liners in place, cheers lads.
I have seen cables lined with nylon get too hot in a small area around the motor. When it cooled the cable was stuck
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Ian
Strongly recommend Hindle being worth a look.
John
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Will phone Hindle in new year, marine stuff might cope with salty Bonneville better than Venhill, cheers Ian.
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I hadn't looked at Landracing for a while.
I'm flattered but I'm not sure that any of it should be considered the gold standard of design solutions. The Buddfab Streamliner was our first Bonneville effort. We designed and built it before spending much time looking at how others solved similar problems.
Shifting was with the rider's left foot pressing (for next higher gear) on a shift lever, the lever was connected to a short link bolted to a spherical rod end. That rod end was screwed into a threaded insert that was glued into a PVC pipe, the PVC pipe ran inside one of the curved longitudinal frame rails. The other end of the PVC pipe also had a rod end that was screwed into a threaded insert. The second rod end was bolted to another short link that was bolted to a lever arm on the transmission shift shaft. So, it was kind of like turning a Bowden cable inside out.
I'm not sure I would do it the same way again, but it always worked without problems.
Eric
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Thanks for the reply Eric,much appreciated, and an interesting solution to the firewall issue, running inside the chassis tubes. Think i will try cable to start with as i didnt dial that sort of solution into my chassis and may be to hard retrospectively. Cheers Ian