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Discussion Starter #1
I've got an old CB750 set of trees that I'm putting on my CB350. I knwo the details of how to do it, I'm not asking the same question that's been asked 6000 times.

My 350 is across town, but I have a set of cb360 trees in my garage... check the handy steering stem chart... see that the bearings are the same size... start grinding.

Drive the stem out of the 360 trees with a 3# rawhide faced hammer and a socket, move on to the 750 trees... stem is much larger.

What's the deal? I thought the trees came from a '75 CB360, but obviously not.

Was there a CB360 out there with a different size stem?
 

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I have CB750's and I've converted all of them to a Tinker bearing kit and got rid of the ball+bearing setup. The goose neck size of the CB 750 is 2" X 7.5". The inside measurement of a race bearing is 1".

Hopes this helps...
 

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seriously?

I thought all relevant dims for the bearings were metric
 

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HackAsaw,
For 1" ID neck bearings you have to order the......

25.44529262 mm ID bearing. Local hardware store is sure to have them :)

JohnnyB
 

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My local hardware only has the 25.4mm bearing. Is the other .04529262 really going to matter, or will it be close enough to work? They don't have any Tinker bearings, but there were some Timkens, will those work? I think it is hard to match up 7.5" taper, too. That is a really wide race.

Ken
 

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ok guys........

I'll admit it's been at least 4 years since I've even held a CB750 or CB359 set of trees in my hands

I typically toss them even for a honda build since I find them ugly as a hat full of rectums

but I have converted a set or two to timkens

I'm begging for mercy........ go easy on me

but I have to know since I don't have a set of honda trees anywhere close enough to measure

is that steering stem really standard?

I'd have sworn it was metric and used metric cones, I'd have sworn the bearing bore in the frame was too and used metric cups.

Am I going the rest of the way senile? I know I am getting old enough I can't stand to read posts that aren't double spaced.

Now I do have a RF900 set of trees on a Norton Fbed and even kept the suzi metric stem although I did have to cut and weld it.... it was waaaaay too long

but it was easy after the stem, metric cones existed that had the same K factor as the standard cups
 

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Hack,
I was making the point...yes you are correct...they are metric. I've never seen inch bearings on any steering neck....in that last 30 years.
So for a 1" ID bearing....you know....you'd have to find that 25.44529262 mm bearing.

Kenessex....well that .045 might not matter...depending on how big your hammer is.

Problem is...last I knew...there were no 1" ID neck bearings used...just metric sizes.
JohnnyB
 

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JohnnyB, I gots a really big hammer, a torch and a 2 x 4, so I should be good to go. I agree that the bearings are metric. I believe that Greg on the Ohio Cafe racer site has many of the common steering stem bearing sizes listed.
HackA, I have had to shorten the steering stem on the FZ600 triples that I put on my Seca 550, too. It was pretty darn easy to do.

Ken
 

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ok, great to learn I've not gone totally senile

on the RF I had to press it out

cut, then weld it back up

machine

heat treat

then press it all back together

it has one of those stems with a huge lower bearing

I guess it seems I have a gift for finding the most difficult way to go about most anything

realized this when 5 hours later, the sidestand on a current build still didn't suit me





but the head is close to being acceptable



but this sucked, putting an early sporty wheel on a CB set of forks slid up in early aftermarket sportster trees




I'm still somewhat confused

I have timken cones laying about for 1" stems

and some for various metric sizes too
 

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to get back on point - when I did the FZR into H1 stem swap the machinist doing the work had to make a small shim since the stems were slightly different, even though both used the same timken bearing size. Make sure the shim is of the same material as the tree and the stem since it will be welded in there with the stem.
 

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I've got the correct Timken numbers, but at home where I can't get them for you for 24 hours. You may also have to grind the steering stop or lower triple so they clear each other. (Probably depends on the year of the 750 model.)
 

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anyone toying about with stuff like this should at least invest in a 15 dollar pair of digital calipers if you don't want to spend for Starretts or whatever

once you know the stem size and cup bore

it's really easy to go to timkens site and look up standard or metric bearings "by physical constraint"

Geeto ........ where your guy machined a shim and welded it all together

I welded and machined the "locating flange" back on mine so it could remain press in or press out

a bit more work but did it that way in case I decided I didn't like the trees and wanted to make up another set

I could easily press the working stem out and use it

oh and my trees are cast aluminum and the stem is moly

couldn't have welded them together if I wanted to
 

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On the later kawasaki h1 the stock stem is steel and the lower clamp is cast iron. They are welded from the factory. Honda I am pretty sure uses the same setup so they are not press in and press out. The 1994 FZR 600 trees I used are cast iron bottom and alloy top. The fzr stem looked press in and out but actually had 4 spot welds on it. Since they did it that way I figured I should just go ahead and weld the whole thing in. It came out nice.
 

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Discussion Starter #15
soooo.. about that CB360 stem?
 

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I've cut and welded a few stems to shorten them when the bottom OD was too short to cut and just press/weld back into the lower tree. I cut some out of the middle, true up the ends on a lathe, TIG weld back together.

Might find it hard to believe but the stem doesn't have a lot of tensile or compression stress on the middle...just the tensile load created by the top bolt...which isn't much. Most of the "weight" is carried by the lower bearing between the lower clamp and the bottom of the frame neck. The stem top and bottom is in shear load between the outer surfaces of the bearing and the upper and lower clamp. On a bike with beefy fork tube clamps you could probably break the stem right in the middle and not even notice it for a while. Top half of the stem can't slide out because the bearing seats against a landing on the stem and nut on top hold it in the top clamp which is clamped to the tubes. Bottom half can't fall out because it's held in by the lower clamp which again is clamped to the fork legs.

All I'm trying to say is...welding a stem is not like you are welding the landing gear on the shuttle or something....it's under far less stress than say the swingarm or something.
JohnnyB
 

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Discussion Starter #17
See... what's got me confused is that despite the bearing supposedly being the same size for the CB750 and the 360... my two stems are a good 1/4" different in diameter.
 

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well they may be a good 6mm difference but not a 1/4 inch

how about coming up with some good dimensions?

impossible for anyone else to help you even help yourself without them

JB, I agree even though the steering head carries the highest loadings found on a motorcycle

I've welded fork tubes back together as long as the weld wasn't below the bottom tree
 

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Discussion Starter #19
it's a moot point really, and I was just asking for curiosity's sake, as the 360 is long gone... I saved some parts for future prjects, the tress were one of those parts. i was under the assupmtion that the 360 and 350 stems were the same size, so i figured I'd give 'er a go.

seeing the difference in stem sizes just got me thinking... and seeing as how I don't have my 350 in my garage, it got me worrying that maybe this wasn't as easy a swap as I've been led to believe.

so... it seems that I will ask the same question just for reassurance... the 350 stem is a press fit into the 750 bottom tree, correct?
 

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Rat...the Honda trees I've taken apart, the stem is pressed into the lower clamp and then welded around the circumference on the bottom of the clamp. So it's not like you grind off the weld and it falls out, you'll still have to drive it out of the clamp. Not has hard as a true press fit, but you can't pull it out by hand.

I can't answer if the 350 stem fits the 750 lower.

So I'm...you know...just typin sheeet cause I can type so fast.

JohnnyB
 
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