ADVrider (
-   Airheads (
-   -   airhead front crank bearing (

JonnyCash 12-10-2012 06:07 AM

airhead front crank bearing
On a junk crank I have laying around, I went to pull off the front bearing to then remove the timing gear. I has not been my impression that this bearing is usually much trouble to remove. This crank has been out of service for 8 years, but isn't rusty. I put my three legged puller on the bearing and started putting the pressure to it, but got nothing. I then got out the propane torch and gave the bearing more and more heat, but still got nowhere. Since this is a junk crank, and will never again be used as a crankshaft, I went for the OA torch, surely that will get it. More and more heat, tightening my puller harder than seemed prudent. The balls and inner race were glowing brightly but still not budging. The puller's hub broke, and the bearing is still in place.

This was all very interesting, and an eye-opener. I have been planning to replace the timing chain and crank gear on my /5 this winter, but after this, I'm worried that this sort of thing will happen, and I'm not willing to destroy good parts, like I have this junk crank. I guess if it came to this on my /5 I'd be removing the crank from the engine and cutting the bearing off, but I sure don't want to have to do this.

Is this bearing often this kind of trouble to remove? I just can't believe how hard it is stuck on there. For the record, generally speaking, I am a patient worker who does not break things. I've done a fair bit of this sort of thing, but this seems to be a special case. Thanks for any insight.

bmwrench 12-10-2012 06:19 AM

I pull the front bearing and crank sprocket simultaneously by pulling against the back side of the sprocket. They are sometimes quite difficult, and you need a good puller.

disston 12-10-2012 07:18 AM

A bigger puller will probably get it off. If you were pulling the bearing and not the gear/bearing combo I can't see it not coming off tho. Are you pulling the two parts or just the bearing? What sort of backing part did you break? I use a bearing splitter for this.

Sounds like you are using a steering wheel type puller. Too small anyway, what ever it is.

DiabloADV 12-10-2012 07:30 AM

A proper splitter and a press will get anything off. I broke a puller trying to get a timing sprocket off (and tore up a tooth on the sprocket). Took it to the shop where they have a press. Bink. Came right off with no fuss. Pushing is better than pulling...

But yes, that means taking the crank out of the motor.

Cordless 12-10-2012 08:58 AM

I took that bearing off a junk /5 crank with my 20 ton HF press. I set it in the press then squirted Kroil into it for a day. Worked very well.

Upon closer look, I think that crank could be reused.

The press was fairly cheap when I used a 20% off coupon and a sale price. The press does take up some room in the shop, though.

hardwaregrrl 12-10-2012 09:18 AM

Did you hit the puller with an impact wrench?

photomd 12-10-2012 09:35 AM

Here's how I did it

Look at post #24. :1drink

brocktoon 12-10-2012 11:16 AM

I tried a decent-sized bearing puller. The Clymer manual recommends putting a penny on the nose of the crankshaft to prevent the bearing puller from damaging the threads. I ended up pushing the penny right into the nose. :puke1 Bye-bye crankshaft (it was damaged anyway).

I ended up biting the bullet and bought the Airhead multi tool set from Cycleworks. Not cheap, but everything came apart and went back together smoooooooooothly.

supershaft 12-10-2012 12:29 PM

I guess you mean that the crank is in the case and the front bearing web is stuck in the case? Not the bearing stuck on the crank? If that's the case, heat the case more.

JonnyCash 12-10-2012 12:59 PM

On my /5, the crank is still in the bike. The crank I fought with yesterday was out of a junk engine. I got the crank out of the case by unbolting the front main bearing carrier from the case. That all came out very easily, it's the bal bearing that goes into the timing cover that I cant get off of the crank.

Someone asked if I used an impoact driver on the puller bolt. No I didn't, but I did give it a few smart whacks with a hammer while it had a good strain on it.

I'm glad to have this as a preview of what I might encounter when I deal with the timing chain on my /5.

disston 12-10-2012 01:29 PM


There are many different types and sizes of bearing splitters. This is a small one;

Here is a puller and bearing splitter. Looks big and strong enough but with nothing for size comparison it's kinda hard to say.

You will pay hundreds if not thousands of dollars for these tools if you get quality stuff. The "Tool Trucks" like Snap On or Matco are the most expensive. Mail order you can find good quality from OTC and for just a little less than the Tool Truck tools.

Some of the stuff at Harbor Freight is OK but I don't like most of it. I do own some Chinese. Can't argue with the price.

After you take into account the cost and number of tools you would have to acquire it is probably more prudent to get the tool made by Cycle works;

I don't own this because I have all the other odds and ends enough to do the job. This looks like #1 quality and reports are that it will do a good job.

Stan_R80/7 12-10-2012 02:00 PM

It seems to me that the airheads cycleworks tool set ( and a can of Kroil are the tools needed. Sometimes trying to save a dime can cost $500.00. YMMV.

Humboldt Airhead 12-10-2012 04:29 PM

It sounds like your 3 jaw puller was on the outside race of the bearing. With this set up you will fight the bearing comming off as it will dish slightly forcing the inner race into the crank.
If you are able to get behind the inner race it would probably come off. That is why it is better to grab behind the sprocket with a splitter.

JonnyCash 12-10-2012 04:49 PM


Originally Posted by Humboldt Airhead (Post 20220790)
It sounds like your 3 jaw puller was on the outside race of the bearing. With this set up you will fight the bearing comming off as it will dish slightly forcing the inner race into the crank.
If you are able to get behind the inner race it would probably come off. That is why it is better to grab behind the sprocket with a splitter.

It was indeed under the outer race.That makes perfect sense, and I hadn't considered that. Thank you. I've got another larger gear puller, whose legs I can alter a bit to let me get under the gear. Its nice to have this junk crank to experiment with. Tomorrow, I'll work on it and check back in. Thanks all for your suggestions.

bmwrench 12-10-2012 06:19 PM

I never heard of using a penny in the end of the crank until recently. I screw a short 8mm socket head bolt into it. This protects the end of the crank and helps keep the puller screw centered.

Times are GMT -7.   It's 08:05 PM.

Powered by vBulletin® Version 3.8.5
Copyright ©2000 - 2015, Jelsoft Enterprises Ltd.
Copyright ADVrider 2011-2015