And dont use locktite.
Dont know if u did...
Dont know if u did...
G: Gearbox (Twin) Layshaft bearing problems
- Thread starter oilyrag
- Start date
. . . . . and don´t punch lock bearings - horrible practice, you don´t really expect to have roundness of an outer race after that, do you ? These gearbox bearings only do max. 3000 rpm so not a critical place regarding internal running clearances in the bearing.
When a bearing is a tad tight when engine cold, I would not care. You cannot possibly operate an internal combustion engine at 20 degreees case temperature in our world for a relevant time, it just heats up soon. I always set the shrink fit of a bearing in an alu case so it will be free at about 120 degrees to drop it out later at that temperature with a little help of a hot air gun while you do repairs eventually. No, I NEVER did punch locks to bearings - miserable bodges when you run out of ideas.
Vic
When a bearing is a tad tight when engine cold, I would not care. You cannot possibly operate an internal combustion engine at 20 degreees case temperature in our world for a relevant time, it just heats up soon. I always set the shrink fit of a bearing in an alu case so it will be free at about 120 degrees to drop it out later at that temperature with a little help of a hot air gun while you do repairs eventually. No, I NEVER did punch locks to bearings - miserable bodges when you run out of ideas.
Vic
There is a definite difference between staking a bearing and punch locking. The original light punch marks done at the factory was to stop the bearings falling out when assembling all the parts into the hot cases, not to actually hold the bearing there permanently. I've had cases where a 1/4" diameter punch was used all around the bearing and this definitely distorts the housing, the inner bearing struggles to enter the outer race. I have repaired about 4 sets of timing side cases in the last couple of months, all with steel sleeves, about 3 thou interference and then the bearing is a nice cold press fit into the steel sleeve with about 3 to 4 tenths of a thou interference. Timing side sleeve is about 2 to 2.5 mm in thickness, drive side a bit more.
Greg, why did you choose steel sleeves ? I know Yam SR and XT have cast iron sleeves for the crank main ball bearings but don´t know the theory behind it. I had pondered over brass sleeves but in the end I took 7075 alu sleeves for the knackered HRD bearings resp. the metric alternatives in my projects, just to have same conditions as standard but certainly with my calculated shrink fits. So I know how to use heat with ease to fit and disassemble when pairing an alu case with steel components like bearings. With a correct fit in the beginning alu cases should last ages - at least longer than my expected life span . . .
Vic
Vic
Vic I'm not sure there is a right or wrong answer. The series "A" machines used a large steel insert in the drive side to support the main bearings. I was a little worried when we first did this that when installing an aluminium alloy type sleeve, that it could expand rapidly as it goes into the case, and grab. I doubt this might happen, but who knows. I have seen brass sleeves before.........I feel that a steel sleeve is actually increasing the size of the outer race, and that seemed to be the best solution to me. We have done probably at least 10 crank cases this way now, and we use to also make the sleeves with a hat section on them, mostly on the drive side. It really involves increasing the surface area of the bearing/case housing without machining the housing too large that you weaken the housing too much. I have seen this done on some engines that can ultimately end in destruction if too much strength is lost, particularly on chopped twin engines where too much of the original primary housing has been completely removed, and main bearing tunnels opened too far. It split the case right through the drive side main bearing housing because of this.
Why would you not just hard chrome the bearing race and regrind to suit? It is a common practice here. No two ways are wrong just curious about peoples thinking.
My Rapide has a steel sleeve on the drive side and is fitted with a pair of (tapers pointing in) Timken tapered rollers bearings. We hold about .003 crush on them by making the hardened spacer between the inner races to suit. Pretty easy for the assembly process as well. When I fist ran the bike some 33 years ago it went 100 miles and rolled a cage in one bearing causing a complete strip. On examining the remaining bearing you could see where the cage was defective and almost stamped through at each of the the little separator strips. They caused a huge discussion on how much crush on the bearings. They were changed at about 55K miles and the second set are still in there. I suspect they will last pretty much forever, or until the Crank wears out, when for 1/4 the price of the correct bearing they will get replaced!
Sorry to side track but the steel sleeve has been just fine there for a longer time than 95% of the engines will ever go nowadays!
Sorry to side track but the steel sleeve has been just fine there for a longer time than 95% of the engines will ever go nowadays!
From the early days on Harley cast in place steel inserts which held up well.
On their modern engines now you can buy a kit to do the same thing.
https://www.hotbikeweb.com/jims-timken-crankcase-bearing-install#page-15
On their modern engines now you can buy a kit to do the same thing.
https://www.hotbikeweb.com/jims-timken-crankcase-bearing-install#page-15
Interesting reading for those who consider doing this kind of conversion on a Vin. When this is done on a Vin then the flange on the taper roller housing is on the outside of the main shaft tunnel, i.e. the primary drive container and the same idea of six screw holes through the flange is used. The outer part of the original crank case tunnel has to be machined down to allow for the thickness of the flange. Additionally a left hand screw thread can be machined into the outer end of the new bore to take an oil seal. As far as I know the Vin conversion does not use any oil holes like the Harley version above but several Canadian users have covered very large distances with no lubrication problems.
Thanks Timetraveller. Mine indeed has the LH screwed in seal holder, but I only knew of one other bike that was like this and it was converted back to stock after my misfortune. Who else?