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Gear Linkage Bodge
By Ren Withnell
Any bike with linkage between the gearshift and the engine seems to suffer with slack. Even new motorcycles have a little excess movement but my aged CBF125 gear change had more freeplay than a 6 year old in the summer holidays.
You don't notice. You don't notice how bad your chain feels until you fit a new one. You don't notice how bad your tyres feel until you fit new ones. And you don't notice how slack your gear linkage has become over the last 40,000 miles until you wonder why it's hard to get into gear these days. I was just rattling around the bike and noticed an awful lot of rattle in the linkage. I figured it's about time I looked behind those rubber covers to see what horrors I can find.
What will I find beneath those rubber covers?
What I found was everything was worn! Gee whizz, I'm a genius I should do this for a living. The linkage on the cheap CBF 125 has no fancy ball-and-socket joints, just a bent piece of metal that passes through a hole in each end secured with a couple of split pins. This is low tech and even when new I doubt it ever had the chance to be a slick mechanism. However like most things on the CBF it has proven "good enough" for the last 40,000 miles and you can't argue with that. I decide that the split pins are almost worn through and the link bar could be "upgraded" - Ren style.
Out with the tools...what could possibly go wrong?
Have I fixed it yet?
I...I must say that for once I feel that my bodge is an actual improvement on the original item. Each bolt is double-locked by putting threads in the link bar and also using nylock nuts. With just a tiny bit of filing the 8mm bolts are a snug fit in the worn out holes of the lever and the actuator. Riding the bike is a revelation and selecting gears a lot easier with a lot less movement of my left foot. It has brought to light though the amount of wear of the gears inside the engine. Neutral is still hard to find and the whole gear change certainly does feel "worn in" if not "worn out".
The bar is threaded too so the nut locks everything into place.
I hope my new linkage will last for many more miles, I can't see any reason why it shouldn't.
Reader's Comments
Carl said :-
Think I need to do something similar with my CBF 500.
01/01/2000 00:00:00 UTC
P said :-
Thats a nice simple mod. My CBF125's gear linkage at just 860miles when i bought it was very sloppy. I have been thinking of making a linkage with bearings but tbh little to be gained over something much simplier like yours.
28/01/2017 09:51:27 UTC
Ian Soady said :-
You can actually get rose type joints very cheap these days which would get rid of all the slop. A bit of 6mm allthread and a couple of nuts and job's done.
I intend to lengthen the gear lever on my Super Four as it seems to have been made for people with ballet dancers' feet (although waiting till I've ridden it seriously) and will be using a couple of these to replace the peened in existing ones. The Honda of course is very sensible having left hand threads in one end so allowing the length of the linkage rod hence the lever position to be easily adjusted.
www.ebay.co.uk/itm/282020032405?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AM...
28/01/2017 10:20:09 UTC
Ren - The Ed said :-
Hi P and Ian.
P, the original linkage on the CBF is basic to say the least. I'm not convinced my simple bodge would make it much better at a low mileage - its just that at the high mileage on my 125 it was VERY sloppy.
Much as it pains to admit it Ian's rose joints off ebay seem cheap and are probably the most effective. That said with smart rose joints and stainless threaded bar it would look far too smart and professional for for my dirty old dog.
28/01/2017 14:35:43 UTC
Ian Soady said :-
I have a spare rusty link rod (proper Honda with left and right hand threads) you can have but of course as it's "classic" it won't be cheap......
28/01/2017 15:18:51 UTC
Ren - The Ed said :-
OH Ian you're just too kind. Unfortunately it is against my religious and cultural beliefs to actually spend my own money on something I can create out of scrap items.
28/01/2017 15:44:36 UTC
Ren - The Ed said :-
P and Ian - the part that is most warn isn't the linkage any more but the bushing where the lever rotates. Circled red.
28/01/2017 15:48:46 UTC
Ian Soady said :-
Bodged loads of things like that in my time (but don't tell the VMCC!). Basically all you need is some thin (.005" - .010" or so) steel shim - cut a strip to take up the wear and assemble with plenty of grease. Got me through several MoTs in the good old days......
Shim steel is usually quite hard and lasts reasonably well in this sort of application.
Of course I don't do things like that any more now I have a lathe.
And of course if you'd greased it in the first place it wouldn't have worn. Easy enough to pop the bolt out and slather everything when you do a service.
29/01/2017 14:37:51 UTC
Ren - The Ed said :-
Due to a lack of seals if I were to grease this pivot point the grease collects road dirt and becomes grinding paste.
Unfortunately we all seasons commuter types aren't afforded the luxury of a full strip and rebuild after every ride.
I shall acquire some shim steel and give it a shot.
29/01/2017 18:00:28 UTC
Borsuk said :-
Once you have slathered it in grease wrap some Denzo tape (or similar) around it. The amount of movement in the linkage is only a few mm so a good wrap with Denzo will keep the road crap off of it. horrible stuff to fart around with but works wonders. We cover all sorts of bits with it at work and that is an extreme high humidity salt environment.
29/01/2017 19:14:28 UTC
Ren - The Ed said :-
Denzo tape? That's a new one on me I'll have to look that one up. I wonder if it would be possible to create some kind of rubber cover. I've seen this mouldable rubber putty that sets yet remains rubbery and flexible. I'll add a link to one example product.
www.versimold.com...
30/01/2017 11:19:39 UTC
Ian Soady said :-
I've never heard of denzo tape but I would use something like self-amalgamating tape if I was bothered about grit getting in (TBH if there's enough grease there won't be room for it!)
The good thing about this tape is it's very conformable (stretchy to you) and sticks only to itself not the substrate so it's easy to make a boot.
To remove it you need to cut it.
I always have a roll in the car for emergency repairs of hoses etc as well as a superior form of insulating tape, and one in the garage for various odd jobs on the bike.
Like this:
uk.rs-online.com/web/c/adhesives-sealants-tapes/tapes/self-amalgamating-tapes/...
30/01/2017 12:58:11 UTC
Borsuk said :-
Misspelled it. Denso tape. Hated it as an apprentice but love it now some other poor sod has to put the stuff on. ??
30/01/2017 13:24:28 UTC
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