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Post by raychappo on Jun 25, 2012 9:31:08 GMT -5
I'm going to renew the bearings in the headstock during the current restoration.
I was going to change to tapered roller bearings but I've heard someone else on the forum saying that tapered roller bearings that are supplied off the shelf have an overall thickness that is a couple of mm greater than the stock ball races and this makes the distance between the yokes a couple of mm greater which causes the headlamp ears to be slightly loose. They suggested getting a couple of mm ground off the tapered bearing to make it thinner.
I'm wondering whether I should buy a set of standard ball races or a tapered set.
Any comments?
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Post by snowrench on Jun 25, 2012 13:19:03 GMT -5
Well, a couple of thoughts from a former motorcycle tech... First, either ball or roller will suffer from the inherent fault of the application, which is that the bearings never really get to turn, which would spread lube and distribute wear. The result is "burnelling" which is essentially wearing a divot into the race, which can actually result in the bearing favoring that spot, causing the front end to stick slightly in the straight ahead position. Running the bearings too loose accelerates this process. This problem was very pronounced in the newer Harley springer front ends. If other adjustments weren't made correctly, the front end was too stiff, not soaking up shock, and the bearings took all the abuse. Harley issued a special neck bearing grease to address this. It had special mineral additives which resisted wear at high pressure and strong film strength. I use it on all neck bearings.
Balls vs. Rollers... Rollers are stronger and truer. Balls would be an easier installation. Balls will require that bearing preload be maintained more carefully. The REAL solution would be sealed bearings. I don't know if the RE5 neck lends itself to fitting a grease zerk. If there are no frame openings in the neck, drill and tap a zerk into the neck. Makes greasing a piece of cake. Frequent adjustment and grease will make either bearing last a long time, just be careful with the pressure washer.... If it were me, I just replace the ball bearings and races, and do what I can to keep water out. Tapered rollers will provide better handling, but only to someone really pushing their bike. Grinding rollers down is an interesting idea, and feasible, but I wouldn't do it to a wheel bearing.
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Post by wayne on Jun 25, 2012 18:47:37 GMT -5
I fitted tapered bearings that I bought from Rotary Recycle.
The bearings were too fat but only because there is a step on the triple clamp shaft that prevents the bearing from sliding down the shaft that little bit more.
This is a "known" issue for GT750's as well.
I fixed it on the RE5 by machining the step on the triple clamp shaft down a few mm. Some people apparently just grind it down but I think that's a bit risky if you go too far.
This allows the bearing to seat properly and as far as I can see, I have no gap and rattling headlight ears which some people seem to end up with (perhaps they didn't machine the shaft, I don't know).
The mod has been on for around 5,000 miles. Tapered bearings have an initial bedding in which requires re torquing within a few hundred miles and I just recently found them loose again so tightened it a bit more.
Just an aside, I have a seat-of-the-pants feel that the original ball bearing bikes actually handle better. But they are a lot more finicky to torque correctly and keep correct.
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