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Friday, December 9, 2016

Improving your Royal Enfield four-speed shift linkage

The nylon shift linkage bushings, new (left) and used, and the bronze bushing
(with a flange) I used to replace them in my left-shift Royal Enfield Bullet.
Part 2

I've called it "the worst part of a Royal Enfield."

Lucky for you that you probably will never have to replace Part No. 113066. That's because, unless you have a Royal Enfield Bullet imported to the United States in the 1990s with the left-shift, four-speed Albion transmission, your motorcycle doesn't have it.

No. 113066 is a nylon bushing that helps hold together the crummy shift linkage behind and below the transmission on these Royal Enfields. The linkage transfers shifting from the right — where Redditch put it and Madras kept it on Bullets that stayed in India — to the left, where the U.S. Department of Transportation required it be.

Being essentially just a bit of plastic, these bushings eventually succumb to heat, oil, dirt and wear. Shifting, already sloppy because of the complicated linkage, gets worse. My experience is that first gear disappears, forcing you to make second-gear starts to get home.




More bad news: those little white nylon bushings (you need two of them) are now out of stock at Classic Motorworks and Hitchcock's Motorcycles. The new Royal Enfield North America isn't likely to bother offering 50-cent pieces of nylon that fit only Royal Enfields sold before its time.

Fifty cents? I would have paid $25 apiece for the little buggers, rather than have my Bullet become a very large and stationary garage ornament. Sooner or later, all the U.S. Royal Enfields with the left-shift bodge will become motionless thanks to Part No. 113066 wearing out.

The bronze bushings I purchased to replace the stock nylon bushings.
They cost me $1.31 each. Hopefully I'll never need to replace them.
So here's what I did. I replaced the little nylon losers with stout looking bronze bushings, purchased from Miller Bearings for a buck-thirty each. These have a flange, which will eliminate the need for one of the washers used in the stock linkage, eliminating some wiggle motion. The stock center pivot pins fit into the bronze bushings perfectly.

The metal bushings, Part No. EF060808, are a bit bigger, requiring that I enlarge the holes in the linkage arms slightly. But that was OK because it was a chance to make the holes the tightest fit possible for the bushings, eliminating more of the monkey motion in the linkage.

Remove the rear wheel to ease access to the bolt holding
the top of the shift linkage to the crossover mechanism,
then "fish out" the linkage without removing the primary covers.
Yeah — but only some of the wasted motion was eliminated. Here's why:

Once you fish the linkage out from behind the inner primary case, you'll be confronted with a very sorry looking piece of homemade wishful thinking. The arms are crudely made, to say the least, and they are held together by cotter pins. This mechanism is never going to give precision results.

No need to remove the lowest arm of the linkage as you can
reach it under the primary. I had to file the holes to get
the bronze bushings to fit (yes, this link has a mystery extra hole).
But I'm not in this to prove I'm a better engineer than Dilbert. I just want the motorcycle to move under its own power.

So the fact that my new bushings are metal instead of plastic, have a flange the nylon ones didn't, and fit precisely in their custom filed holes, is the best I can do.

Bronze bushing in place holding the top two arms together.
Flange eliminates the washer usually needed under the cotter pin.
I re-used the stock center pivot pins, which have a flange of their own
holding things together on the other side.
Oh. And I even used brand new cotter pins. Talk about your Brough Superior workmanship!

So, did it work? Does my Royal Enfield now snap from gear-to-gear with a smart salute?

Well. No. But it does change gears, if I'm careful and patient.

In other words, the metal bushings are not noticeably better than the old nylon ones at insuring accurate shifting. But perhaps they will not need to be replaced as often. I hope so.

Follow along in coming episodes as I continue to address the woes of "the bodge" with my own admittedly amateurish efforts to improve it.

Part 1: Improving the gearshift action.

Part 3: Improving the linkage connection to the gearbox.

Part 4: Improving the linkage fit.

4 comments:

  1. A "cob-job" doesn't negate a "bodge-job." Get the right side conversion kit or a new left side 5 speed tranny. Either way, you'll be happier riding it and have a far easier time when it's time to sell it.

    ReplyDelete
  2. You certainly didn't 'beat about the bush' on this article then!

    ReplyDelete
  3. I did a similar mod on my 2000 Bullet and the difference is amazing!I got 3/8 x 1/2 bronze bushes at Ace Hardware and spent time drilling and fitting the linkage with 3/8 lock nuts and bolts with thin brass washers. I turned the nuts and bolt heads thinner on the lathe for clearance and adjusted the side play and tolerances by lapping on 400 grit. Blue Loctite secures it all. I can almost find neutral while stopped and at any speed can change gears freely. I might try to find a castoff LH linkage as a backup just in case, but I'll skip the $$$ RH conversion.

    ReplyDelete
    Replies
    1. I like the idea of using bolts and nuts instead of cotter pins. And, like you, I would like to round up a spare LH linkage. I could modify and improve it at leisure instead of having to take the bike out of service.

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