Topic: Timken bearings in fork head [done] steers way better

[Don R]

After reading posts on this site about the timken bearings being better than the all balls or [offshore] and gleaning the part numbers  and washer thicknesses I spent the day finding and ordering everything I thought I needed. Tonight after reading 20 pages in another area of the site I learned I ordered bearings that will need machining before  they can be used. I may as well toss em in the trash and  buy a kit because it will cost more than a new kit to have them ground at a machine shop. Since I have 2 bikes to do I got 2 sets. So now I'm out 50 bucks and an afternoon. It would be good if this info could be corrected to save others this hassle. Thanks for reading my rant. Back to your regularly scheduled program.  D.  

[Spanner 1]

Wow!...I agree with you Don, most replies here are to do with problems that may have several possible solutions, so it's 'pot-luck' as to who gets it right !, but on matters of
specifications I think a reader has a 'duty' to correct the post if it's mistaken and they have double-checked the correct info......

[mystic_1]

I've seen references on this site many times to the effect that the head bearings on a CB750 are NOT an "industry standard size" and therefore standard bearings need to be machined (ID of the inner race IIRC) in order to work.  Which posts say otherwise?  If you can point out the threads we can go around and put the disclaimers where they need to be.

mystic_1


Edit:  Also, consider selling your timken bearings to someone on this site, many of the members here have their own lathes etc and could probably do the machining themselves.  -m

[Spanner 1]

Apparently, Don R read all about how great Timkin head bearings were with no reference to the fact that they need to be machined to work in the races.......right ? Who's at fault , the reader or the poster ?

[Don R]

  I fully admit to being a dumbass.    This is just a heads up to become fully informed before proceeding with your project.
   I have spent hours on here the last few days it will take a while to find the post again. There is a lot of valuable information on this site and the fact I am riding my bike now is proof of the help available. Without this site and all you coaching me my bike probably wouldn't even be running yet.

[Alan F.]

Also, consider selling your Timken bearings to someone on this site, many of the members here have their own lathes etc and could probably do the machining themselves.  -m

Anyone who's pressing out their stock steering stem for a fork swap can easily have it turned down in a lathe to fit your bearings before the stem is pressed into and welded to the new lower triple clamp,  so don't toss them.
-Alan

[Duke McDukiedook]

Could this possibly be posted in the FAQ section?
I know I'll be replacing my steering head bearings sometime soon and this would be good info to know.

[mystic_1]

Here is relevant info:

This is from Thoughts of Hondaman thread in the FAQ section, mentions Timken steering head bearings, gives old (70's) part numbers.

http://forums.sohc4.net/index.php?topic=7401.msg103752#msg103752

The Timken bearing numbers are:
Lower: 07100
Upper: L45449
The lower washer is: O.D.: 1.750", I.D.: 1.245" (1.250" will do nicely, too). Thickness can range from 0.100" to 0.125" .
The upper washer is: O.D.: 1.500", I.D.: 1.000" to 1.020". The thickness can range from 0.040" to 0.060" and it will fit.

The Timken numbers I have are circa 1972, just removed from my bike. If they have changed, and I can find the new numbers, I will edit this post later. I will be trying to locate some of these bearings, because I just had to install one of those "green kits" in mine, if only to get it back on the road before Fall...

This is from the Tapered Steering Bearing thread, update from Hondaman that mentions the mods needed with modern Timkens.  Should be added to the Thoughts of Hondaman thread as an addendum to the existing post.

http://forums.sohc4.net/index.php?topic=1516.msg545663#msg545663

Heyjones:
That's a partial reprint of one of my early posts. You'll find that the Timken bearings today will need some work to match the ID and OD dimensions mentioned in the article: they don't make them in the finished sizes I used to be able to get with those part numbers. Specifically, the OD of the lower race will have to be ground down, and the ID of the upper bored. I'm working on a jig to make these on my lathe so I can offer the Timkens myself.

There are some KML bearings available from All Balls in their kits (red boxes) with spacers and seals in the kit, these are not bad. There are also some NTN bearings, in a green box, available out there from some suppliers: I've not had good long-term performance from these. They seem to have soft races which need quite a few tightening adjustments over the first 5000 -10000 miles or so to settle in, then they drag and dimple sooner than the others, at maybe 30,000 miles over time. (Just my experience with the green-boxed brand).

HM

mystic_1

[NickC]

I do have a timken bearing book i'll dig through, see if i can find some cross references/dimensions

[HondaMan]

Reference to the Timkens:

In 2006 I contacted Timken about getting those bearings possibly manufactured again. They said the demand for these OD and ID special dimensions had dropped off so much by the 2000-2002 "Product Review Cycle" that they only offer them now as Specials, in large quantities.

It appears that KML does not think similarly, as they offer theirs still today. 

I have only had the KMLs installed for 5000 miles, so I cannot yet attest to their longevity. I can say that they required 3 tightening cycles to settle in over a 2000 mile beginning, where the Timkens only needed one at about 500 miles. I have not tested them this year for looseness, yet. (Probably should, though.)

The "green bearings" (I call them that because they come in green boxes, labelled "Made in Japan",  but with various manufacturers' names on them) are the ones I dislike: they seem to never settle all the way in, requiring tightening about every 3000 miles. This speaks of metal migration, which usually comes from softer metals.

I'll ask Steve to remove that post from the "Thoughts" collection. 

[mystic_1]

I'd rather see the second post added to the first, and kept for posterity.  It's still good data imo

mystic_1

[Don R]

Thanks for the help, you guys are the best. I still need bearings, given what I've learned, I'm still not sure where to get them?  I haven't ruled out grinding down the timkens if my local machinist can do it reasonably and they would be the best ones. I did find suitable machine bushings for spacers.
  Dynoman I believe shows [timken type] on their site. So KML in the red box from all balls should get me riding comfortably for a while?
  I really need some quality ride time on this 750, right now it corners wierd and I would like to fix this problem and know it is good before I take it apart for finish work this winter.
 I would also like the info left available, just with the note right there about the grinding.

[HondaMan]

Thanks for the help, you guys are the best. I still need bearings, given what I've learned, I'm still not sure where to get them?  I haven't ruled out grinding down the timkens if my local machinist can do it reasonably and they would be the best ones. I did find suitable machine bushings for spacers.
  Dynoman I believe shows [timken type] on their site. So KML in the red box from all balls should get me riding comfortably for a while?
  I really need some quality ride time on this 750, right now it corners wierd and I would like to fix this problem and know it is good before I take it apart for finish work this winter.
 I would also like the info left available, just with the note right there about the grinding.

Don;
Right now, I think the KML ones are the best bet. They fit well in the 750s I've been working on, and they seem to settle in better than the "green box" ones.

Mystic_!: I edited the original post, and asked Steve to replace the 'Thoughts' one with the new one. It still has most of the original info, plus notes about TImken's recent change of strategy.

I took my Timkens (I have 10 sets) to a machine shop to have the uppers bored, but they didn't wish to do the work. That was last winter: I've been struggling with the non-job situation all summer this year and haven't had the time to make up a jig to bore them on my lathe, myself. I eventually will, but won't go after it until I have my book finished. I need to get that thingie into publication, as I get e-mail for the thing almost every day, now. It's a surprising amount of work, even after the stuff is written!

[Don R]

I bought an all balls kit from my local bike shop. Got em put in today and rode a little between rain storms. It steers so easy I think I may have to tighten em up a little. Maybe I am just used to junk bearings. It had tapered bearings in it already, it is hard to believe they were that bad. If I have to do this every couple years it ain't so bad. My brother and I took our 750's downtown last night. There were people looking at them and asking questions before we even got parked. 

[mystic_1]

Excellent Don, glad you got that sorted.

Re-adjust the bearings in a 100 miles or so after they've seated themselves in.

mystic_1

[Simpson]

Maybe I'm crazy... I just clean, polish slightly, regrease and assemble. Can't tell the difference between my modern bikes. Perhaps I need to test a upgraded fork.

[Johnie]

Excellent Don, glad you got that sorted.

Re-adjust the bearings in a 100 miles or so after they've seated themselves in.

mystic_1

What kind of tightness are you putting on those All Balls when you first install? Hand tight and the 1/4 more or what. Same after 100 miles? Will be changing mine to All Balls this winter in my K4.

[mystic_1]

Here's what I do:

Reinstall everything but leave the top bridge cap nut off, and leave the three top pinch clamps loose.

Prop up the bike so the front wheel is off the ground slightly.

Seat the bearings by tightening the top collar, then turn the bars back and forth from stop to stop.  You will feel the bearings "loosen" a bit as they settle.  Tighten the top collar again and repeat.  I do this two or three times.  Don't go all Rambo on it.

Next, loosen the top collar and then tighten it to just snug.  Center the bars, then give one side or the other a gentle nudge.  Front end should swing through it's arc smoothly until it hits the steering stop.  Tighten bearings until you get just a bit of drag but the front end still turns all the way to the stop when you nudge it.

Same process at 100 miles or so, then check it at each oil change.  Only takes a minute to check.

mystic_1

[Head]

I my self will be staying with tapered  All Balls  head bearings,they also now come with good upper and lower seals,( only ones that I know that come with seals ) + the correct washers for spacing. I just installed 2 sets on 750's and the owners are tickled pink! This is not a plug, But they have very good service,fast shipping,Two days for me,and very good techs, I usually talk to Kevin,and the bearing quality is high! And no muss no fuss there are in, your done. They are in my bikes. Next week I'm replacing the frt & rear,and sprocket carrier bearings on 1,70-2,72s 750's, Wheel bearings I also like "SKF" brand of bearings,I have had no complains what so ever!! Both these bearings cost a little more than the cheap jap ones but the quality more than makes up for it. This coming November 3rd will be my 40Th year working on 750,s
                                                                            HEAD   PS All Balls steering bearing AND seal kit #22-1011
                                                                                                                                                                                                   

[Don R]

My bearing stack looked a little higher with the seal installed and the washer in the kit, so I used 2 thinner machine bushings I already had purchased for use with the timkens. I am thinking the seals will help with longevity. There were instructions about machining the top nut included. I ground down the underside of it until it was flush with the surrounding metal. the skirt didn't fall off so far so I guess I got it close enough. Head, Way to stick with the SOHC! Thanks to all for the input, we all get access to many years of experience here. Priceless.