I have the MNR push-pull gear cable. There is quite a bit of slack on it. That is, if you hold the metal push rod at one end and push / pull the gear lever at the other, the lever moves back and forward several mm before the other end of the cable moves. That, together with the "slop" in my R1 gear change means that you have to mover the lever quite a way before the gear changes. Is this normal?

"""Shudder"""" cable shift.

I've tried it, cables just too slack to get a nice shift in my experience, you really should use a push/pullrod/bellcrank system to get a good shift.
Spoken to a few people who have tried cables in the past, but never again.

Another attractive option is a button shift, solenoid system, these can be homemade, or better still purchased from klicktronic.

Unless this is a proven system that I am unaware of, scrap it and start again is my advice.

Sorry to be so negative!

If anyone has successfully managed cable shift please post some pictures.

cheers, Mark

havent got round to that yet, but could the location where the rosejoint attaches to the gearstick be moved any further away from where the stick pivot is? (wont eliminate 'slop' but would mean less travel overall.. )

hi colin

just checked our zx12 car here and the r1 car and both have about 4mm movement ( at the top of the gear selector end )

are both monting p[lates firmly fixed to the chassis ???

how much free play are you getting on the bike engine lever ?? , you will get some !

we have sold / used 85 + cables so far and only 2 breakages, we have converted many cars too from one of the manufacturers who use a bushed bell crank and rod system that results in travel of anything up to 50mm at the lever end

I've got to agree with Marc, I would be surprised if its the cable. I've got one of his cables and it has been used mercilessly in my brief but aggressive sessions on the track.

I was just asking if it is normal. everything is tightened and firmly fixed. If you hold the pushrod on the cable at the gearbox end you can push the lever backwards and forwards. The reason I queried it is that kit car magazine remarked how little play there was. The gear change itself is quite positive and there is enough feel to get neutral, just, but the throw of the lever is a bit long. I'll happily live with it if it is how it should be, I was just checking.

ian hyne(kitcar magazine) commented on how psitive the cable gear link was compared to the normal pushrod etc,

this was as you know my car,if i wobble(for want of a better word) my stick back and forwards there is minamal movement,but there will always be some on any set up due to the free play in the gearbox of whatever engine is fitted,on mine(blade)it is minamal,and thats after 6000miles and one year

if the throw is too long rather than just slack, sounds like you need to move your pivot point of the lever so it move the cable more.

Shorten the gearbox end lever..

That will reduce the throw

If you can connect the hand lever to the gearbox lever with just one straight rod then that's ultimately the best method, but it's seldom possible. If you need to go around corners, then (apart from using composite rods which add further complications and even more flex) a good quality control cable is the best solution IME.
I have used loads of Morse type cables, but like everything else, you get what you pay for.
All push-pull cables have some degree of lost motion, but the top of the range cables usually have backlash of no more than .005mm x bend angle. The backlash is a product of the clearance between the inner cable and the outer casing. On products using cheaper or inferior materials the clearance is much greater to give the appearance of a smooth action.
Expect to have some sponginess even with a single rod, as other elements in the assembly will flex.

If a rod system is done right there should be minimal slack, so long as you use quality rose bearings such as "Aurora", use lock bolts on them, and keep the rods in best possible allignment with a bellcrank. My system is done this way, and there is no more than 0.5mm slack either way.

And it should be more difficult for me than it is for you front engined guys!! you don't know how good you've got it!

Mark

I should have mentioned;if you ever use rods and have to go around an obstacle (typical with mid-mounted engine installations), what ever you do, don't put bends in the rods. Bends will gaurantee flex in the system. The best way around obstacles is to use bell cranks, though as mentioned above, the more rod ends and bell cranks the more oportunity for slop to creep in.
If you have to use more than two bell cranks, consider using a cable.
If I can't use a single rod, I'll use a cable.

I am using rod ends but the "play" is in the cable not the end. There is a good amount of "straight" in the cable before the ends.

The play, it seems to me, could either be a) that the push rods at one, other or both ends are a bit loose on the cable allowing a few mm or movement between push and pull before any force is transmitted or b) that the cable is snaking up inside the outer when it is being pushed.

Sounds like you have a sloppy cable. Cheapy cables use Nylon liners and opt for greater clearance between cable and liner to achieve a smooth action. High quality cables use Teflon liners and much closer tolerances between cable and liner which results in a much more positive action.

MNR charged me £58 pounds for the cable including rod ends. Not my idea of cheap. Perhaps marc would like to comment again.

hi colin

teflon lined ( same spec as lister gt car )and inc m5 rod ends £58

the rod ends come to £14 of that !!!!!!!!!

next step up from that cable is £98 + rod ends

best regards

marc

p.s dont forget 1mm slop on cable is then multiplied by the length of your lever from the pivot point

best regards


marc

I went and measured the slop in the cable. It was 2 or 3 mm each time I measured it.

cant say ive ever measured on any of the cars i must admit, just going off the two we have fitted on cars here

that from the middle position you move the lever 25mm measured from the top and you engage a gear

i can order you the other one if you like, never had one myself so cant vouch for any difference

or just send the other one back, and we will credit you against last invoice

best regards

marc

Very generous Marc, thanks. If the cable I've got is as it should be then I'll keep it. It would be good if you could measure the slack in one that you have if possible to see if mine is OK.

many thanks,

Colin