WC Scrambler steering head repair

[graeme]

I have a '74 450 scrambler that has a damaged steering head.
The steering bearing inserts are loose in the frame.
The frame has been powder coated with thick garden furniture type PC and the steering bearings are very loose (top one more) even with the powder coat.

Should I heat the steering head with an undersized insert in there and dress it smaller with a hammer?
Set up in a mill and machine the tube larger and insert a sleeve?
Make oversize bearings?

Suggestions????

Regards
Graeme

[Eldert]

how about a conversion to tapered steering head bearings ?

Nigel and Phil both sell a kit or you could make your own cups and use Honda 26 / 47 mm tapered bearings

Eldert

[graeme]

Hi Eldert

Do the tapered roller kits have a longer section that would press further into un expanded section of the steering head tube?
I've never used tapered roller bearings in a single except for RT

Graeme

[JimF]

Excellent question, and I give you much credit for thinking the conversion through so carefully.

The answer is no, no steering tube extension is provided and so the 'steering column' becomes too short as a result of the installation of the tapered bearing cups. At least it did for me when I converted one bike many years ago.

I had to take the steering column to a competent machine shop. They cut the column and then fabricated a piece to stretch the length. It is more complicated if done correctly than just a straight piece of pipe, and a fellow co-worker gear-head advised me of what should be done which was to bevel both edges of the cut steering column as well as the extension piece for the weld and the machine shop did it without my asking.

The machine shop also warned me that the heat of the welding could warp the column. They welded the new piece in, then put the column with the lower triple tree attached into the chuck of a lathe and spun the thing up to thousands of RPMs. Fortunately the steering column was straight and true (no wobble.) Of course this was extra expense and delay.

A warped column would have left me sourcing a new column and another attempt and expense to lengthen that one.

Would I do this all again? Never. What a PITA. And here's another thing: Fortunately I was not doing this to my stock Mach 1 because the added distance would adversely affect the distance between between the two triple trees making the headlight stanchions too short and yet another modification would be required.

If it were me I would modify the head stock tube along the lines of your original thinking.

This is just my opinion.

Jim

[Nick]

If you can find a larger insert somewhere, either from a bike or for some industrial application, you could then get the OD ground (using centerless grinding) to whatever OD you require. That might be the least expensive way. A bearing maker might also make you up custom race. It's always worth a phone call to talk the people making the parts as they're often very helpful.

If you do grind a race to fit, and the fit is uneven, a touch of Loctite (bearing mount) would do the trick.

From your post it sounds like the powder coating is also inside the steering head where the insert mounts.... If so, it might be better to get that out of there so it's metal-to-metal.

A quick-and-dirty fix would be to get some shim stock and cut out whatever kind of shim you need and then Loctite everything in place.

It might also be worth looking around in the mountain bike parts. Some of those things are running pretty beefy front suspension units. Likewise, the crank bearings on bicycles might be a similar size.

[graeme]

Hello Jim,

I had thought about a tapered roller being taller than the original ball arrangement and I recall someone machining the frame tube shorter to allow for the extra height of the tapered rollers.
It would seem that the bike may have been in a crash or the powder coater sand blasted the inside of the steering head and removed too much metal ????
It doesn't seem to be round either in the ID. So I'm thinking its been crashed front on.
If the tapered roller assembly had a longer top and bottom press in sleeve it may be worth going that way, but if it's the same length and diameter it will be loose also?

Hello Nick,

Thanks for the suggestions, I will definitely be removing the powder coating in there, and from the rest of the frame also.
Speedy sleeve make various metal sleeves that may be easier, I forgot about them.
Thanks

Regards
Graeme

[amartina75]

The bike may have been used for a long period with a loose steering head. Over time that might have made things much worse. It might be possible to use a low melting point alloy to build up the inside of the head tube. Then machine the ID to original dimensions. If you know someone that braizes you could ask them. If your not concerned with it staying original it might be best to make custom cups for tapered bearings. The ones available will be too small as well. You could have them made to press in as long as you want. You will need to have the frame milled down to use your steering stem. There is some info here on making the bearing cups.
http://www.docc.ca/singles/chassis.htm
Good luck

[Scrambler]

I would be more than willing to machine a custom set of bearing races/carriers for you. I made mine to convert to tapered bearings. All I would need is as accurate measure of the ID of your frame bores. Let me know if I can help. I can send pictures of mine being turned on my lathe if needed, really no big deal. Taper bearings are easier than balls.

Mike Mc

[graeme]

Hello Amartina75,
Thanks for your input I appreciate your comments, ideas and the link you posted.
Thanks

Hello Mike,
That is a very kind offer, thank you.
I have a lathe and can make an extended bearing carrier to suit, but I would love to see your carriers.
We have not long moved and I still have to hire a lifter to set up my lathe.
I will pull my finger out and get the workshop set up so I can get into fixing the scrambler up.
Been busy sorting boxes and finding tools etc and I thought I'd post this question to see if others had a fix for this problem.
This bike has had a very hard life, by the twists and bends to the frame it may have been ridden by a fat bastard in the circus. The frame is now straight with just the steering head problem and the crap powder coat to sort out before I can rebuild it.

Thank you all for your ideas and suggestions

Regards
Graeme

[Scrambler]

I just turned up a new set of carriers and made a new longer steering stem. Nickel plate to match the rest of my brite work and I was good to go.
But as noted earlier I am basically cheap and would rather spend time in the shop making parts than buying then out.

Mike Mc