Upper steering head bearing removal?

I need some help figuring out how to remove the upper bearing from the stem.

I drove the stem up from the bottom and it took the bearing up with it.

Is the stem pressed into the upper yoke or is it screwed in? It's a 750 upper...part number 06-0915

I'm afraid of damaging the yoke.


Lesson learned.

I left the original bearings and spacer in when I tore the bike down. They seemed fine and stayed in place when I took the yoke out during disassembly. I thought it would be OK to just re-insert the yoke and draw it down after painting. I had taped everything off but didn't realize that the light coat of paint overspray on the stem would be enough to bind up into the upper bearing. Thinking I could just drive the stem back up and clean up the stem.

Result was the bearing and the stem came up together.

Thanks to OldBritts I have two new bearings...all I have to do is get this one off.

I thought I might draw it off first. If that can't be done I guess I'll have to cut it off unless someone has a better idea.

There are different kinds of bearing removal tools. One is a fork with a ramped surface that can be driven behind the bearing. I think it is actually intended for tie-rods but it might work.

http://www.harborfreight.com/16-inch-ti ... -1759.html

The other is a two piece "dish" such that the two halves are placed on opposite sides of the shaft and pulled together with bolts. It is also an incline plane idea and it forces the bearing away from the surface it rests against. They look like this:

http://www.ebay.com/itm/Bearing-Gear-Se ... 27&vxp=mtr

You could look for or make a wheel puller with long enough arms to reach the length of the stem. Or I would be tempted to drill a hole in a block of soft wood such that the stem was a tight fit. Cut the block in two so that it could be clamped around the stem in a vice. This is to prevent crushing the stem. Then take something like your nail-pulling flat bar and reach in there, and start tapping downward with a hammer on the flat bar, while working around in a circle. My bet it it comes off.

Nice color of paint. Is that a BMW green?



Russ

The stem is welded into the yolk. Non-removable.

A bearing plate and a press or puller would have it off in a few seconds. Jim

Not a bad id to careful flame or heat gun the stem area first. As the bearings are trash anyway I don't bother with a puller to remove but get some sadistic satisfaction as manic BI mechanic by knocking their teeth out with hammer and drift. Heft that steel spacer and think about in being alloy while riding about later.

Nice color of paint. Is that a BMW green?



Russ[/quote]


Thanks

British Racing Green (jaguar) non-metallic for frame and other bits and pieces.

British Racing Green (jaguar) metallic for tank and side panels.



Thanks for the input. I'll be working on it this afternoon. Let you know what I come up with.

comnoz said:

The stem is welded into the yolk. Non-removable.

A bearing plate and a press or puller would have it off in a few seconds. Jim

Click to expand...

Welded in answers my question about options.

I have a couple of different pullers. I'll see what works if anything, otherwise I'll have to fab something up.

Thanks for your help.

hobot said:

Not a bad id to careful flame or heat gun the stem area first. As the bearings are trash anyway I don't bother with a puller to remove but get some sadistic satisfaction as manic BI mechanic by knocking their teeth out with hammer and drift. Heft that steel spacer and think about in being alloy while riding about later.

Click to expand...

"If I can't fix your problem with a hammer, your problem is electrical..."

As an old school airframe mechanic you and I understand each other... :twisted:

I looked at a number of Jag paint codes and found that they differed a lot from year to year. I looked at Jag #254 but ended up going with the BMW color instead. I figured I would be forgiven for using German paint codes on a British bike.

Russ

Regarding the stem in the upper yoke, I have to respectfully disagree with Comnoz : it's not weld . RGM is selling the stem alone http://www.rgmnorton.co.uk/buy/fork-yoke-stems-commando-fits-in-top-yoke_2214.htm.

I had mine replaced on a 72 750 a few years ago because the thread was damaged : it requires an hydraulic press and it retained by a round clip . If I remember well it has to be pushed from the bottom , all along the stem .

JRD said:

Regarding the stem in the upper yoke, I have to respectfully disagree with Comnoz : it's not weld . RGM is selling the stem alone http://www.rgmnorton.co.uk/buy/fork-yoke-stems-commando-fits-in-top-yoke_2214.htm.

I had mine replaced on a 72 750 a few years ago because the thread was damaged : it requires an hydraulic press and it retained by a round clip . If I remember well it has to be pushed from the bottom , all along the stem .

Click to expand...

Thank you for the information. I'll file that away for future reference.

I ended up taking a cutting wheel to the bearing. It's off now.

I did nick the stem with the wheel but nothing drastic.

Thanks for everyone's input and help

JRD said:

Regarding the stem in the upper yoke, I have to respectfully disagree with Comnoz : it's not weld . RGM is selling the stem alone http://www.rgmnorton.co.uk/buy/fork-yoke-stems-commando-fits-in-top-yoke_2214.htm.

I had mine replaced on a 72 750 a few years ago because the thread was damaged : it requires an hydraulic press and it retained by a round clip . If I remember well it has to be pushed from the bottom , all along the stem .

Click to expand...

Well maybe not all of them are welded. I just went and looked at a 2 sets on my shelf. There is clearly a weld bead laid around the inside of the hole. ?? Jim

comnoz said:

Well maybe not all of them are welded. I just went and looked at a 2 sets on my shelf. There is clearly a weld bead laid around the inside of the hole. ??

Click to expand...

I believe the standard stem is a press fit in the yoke, with a circlip at the upper end.

061918 (Norvil part number) STEM - TO FIT 750 & 850 YOKES FROM 141783

Click to expand...

I can see neither circlip or weld on the 71 triples (They look like the L.A.B picture) I have ready to fit new bearings
Why is the bearing so tight on the stem ?
The bearings are supposed to be a interference fit in the frames steering head,the stem with a little grease on the bearing landings should push through nicely before the lower nut pulls the lot up (bearings and spacer tube)

So I didn't think I was dreaming. I had to bead blast one to make sure. Definitely welded. I have another silver set here that looks the same also but I didn't want to blast them.



Then I went to my storage and started pulling rubber plugs. Three of them -with c-clips. Did they start welding the later ones? Jim

comnoz said:

Did they start welding the later ones?

Click to expand...

Well, the two examples shown in my photos are late ones (850 MkIII).

Well I guess I must just be lucky.

I believe both of the welded clamps came from a lot of stuff I bought from a shop that closed some years ago. I guess somebody didn't want them to move. Jim

At one stage when they changed from the old featherbed type yokes to the Commando ones the stem was secured into the top yoke by Loctite. The new steering head assembly was required because the old featherbed yoke dies needed replacing, and (at least) the bottom yoke was very expensive to manufacture, as it had a hollow bit. The rationale was, that on the featherbed yokes the stem was brazed into the lower yoke, this was an expensive operation (close fits, another operation away from main assembly area, jig required etc ), so alternatives were sought. Advice was sought from Loctite, and a number of representative samples made, as there was considerable doubt that Loctite would be adequate. The samples were assembled and subjected to a push out test. When pushed out the stem took some of the yoke with it, the actual bond line remained intact. Not only that but the assembly could have wider tolerances (the reason for the knurl) and the stem was cheaper to make as well, as the machining cost was much less. The circlip is just a locating device to prevent the stem being pushed in too far on assembly, and it replaces the raised portion that would have required the machining down of the full length of the stem, its far cheaper to simply machine a groove than to reduce the diameter. That's my memory anyway.
Of course they may have reverted to welding or brazing at a later stage, or a previous owner may have welded or brazed it, as there seems to be at least a couple that have been welded or brazed.
cheers
wakeup

Re: Upper steering head bearing removal and stem configurati

The reason I posed the question in the first place is because all three parts manuals I have(750 Interim parts List, 850 Commando Parts list +750 from engine #212278, and 850 Commando Electric Start) illustrate the upper yoke and stem as an assembly.

It would appear from the responses here that the "normal configuration" is that the stems are an interference fit, pressed into the upper yoke from the bottom of the yoke, and that a clip is used to prevent pushing the stem in too far.

Interesting discussion. I learn every day from this board.

Re: Upper steering head bearing removal and stem configurati

XMarlin said:

It would appear from the responses here that the "normal configuration" is that the stems are an interference fit, pressed into the upper yoke from the bottom of the yoke, and that a clip is used to prevent pushing the stem in too far.

Click to expand...

I think the stem is actually pressed in from the top until the circlip locates against the shoulder of the recess.