Topic: Front End Out of Alignment...

[Hrvatski Medvjed]

I recently installed tapered bearings on the front end of my 73 500k. I did a lot of other stuff too (not related to suspension or frame modifications) and am finally getting it out for initial test rides...well, the bike WILL NOT go down the road in a straight line. How can I troubleshoot this thing? It feels like the front end wants to wander all over the place. Kinda scary, really.

Any help is greatly appreciated...again.

Thanks!

[Tempast]

Bearings are probably too tight.

[Nic]

Yep, bearings too tight, I had the same problem with the tapered ones, in the end mine are a bee's dick tighter than hand tight.

[HondaMan]

Yep, the bearings should be "set" to 40 in-lbs, then backed off 1/4 turn, then snugged back down. After about 1000 miles, you will need to repeat, as the races will settle a bit into the steering head. Then it will stay in tune, for like 40k miles.

[martin99]

Yep, the bearings should be "set" to 40 in-lbs, then backed off 1/4 turn, then snugged back down. After about 1000 miles, you will need to repeat, as the races will settle a bit into the steering head. Then it will stay in tune, for like 40k miles.

Is this with forks and wheel not fitted? Wouldn't the extra weight of the front end have an effect on torque values? And whether the front wheel is on the ground or off?

Genuine question, often wondered about this. When I adjust mine I have the wheel off the ground and tighten until I can turn the wheel lock to lock with slight resistance, but not too much to stop it 'falling' into full lock position under it's own weight. Bit of an experience thing I guess. Hope I've been doing it right all this time!

[Hrvatski Medvjed]

Thanks everyone. I definitely have them too tight. I'll loosen it up tonight and confirm that this was the issue.

One last thing - do I set the tightness with the bike/front end off the ground or with the rubber on the pavement? Do I need too loosen and of the fork tube bolts when adjusting?

Thanks again!

[70CB750]

If the head bearings adjustment does not fix it, loosen up the front fork and tighten it again. 

Top bracket, bottom bracket, wheel axle. I always tighten the axle first, bottom bracket second and the top bracket last since the top bracket is weakest.  Are your fork tubes straight?

[Vinhead1957]

Also make sure the fork tubes are at the same height in the clamps.

[Hrvatski Medvjed]

If the head bearings adjustment does not fix it, loosen up the front fork and tighten it again. 

Top bracket, bottom bracket, wheel axle. I always tighten the axle first, bottom bracket second and the top bracket last since the top bracket is weakest.  Are your fork tubes straight?

Thanks! Do I leave the wheels on the ground or jack it up?

[mcswny]

Yep, the bearings should be "set" to 40 in-lbs, then backed off 1/4 turn, then snugged back down. After about 1000 miles, you will need to repeat, as the races will settle a bit into the steering head. Then it will stay in tune, for like 40k miles.

Curious, is there a special torque wrench for a spanner to get it to 40 in-lbs, or is this just based off of years and years of "feel"?

[70CB750]

I leave the front wheel on the ground with the bike on centre stand.

Are you really bear from Croatia?

[Hrvatski Medvjed]

I leave the front wheel on the ground with the bike on centre stand.

Are you really bear from Croatia?

Thank You.

yes. Croatian Bear.

[70CB750]

I am from Prague, similar language.

[HondaMan]

Yep, the bearings should be "set" to 40 in-lbs, then backed off 1/4 turn, then snugged back down. After about 1000 miles, you will need to repeat, as the races will settle a bit into the steering head. Then it will stay in tune, for like 40k miles.

Curious, is there a special torque wrench for a spanner to get it to 40 in-lbs, or is this just based off of years and years of "feel"?

With all [new] tapered bearings, you can get very close with their "feel". As you tighten them, move them back & forth about 10-30 degrees, and there will be a point where they suddenly increase in friction. This is the torque where the sheet metal cage just distorted itself to align all the rollers it has, at once: then back off from this point, and then snug back down to where friction just starts again (on new ones). The first friction point is around 35-50 in-lbs for this "set", the latter is the point where the full length of the rollers just contacts the full face of the races.

After an initial run-in period (like on car wheels), the surfaces irregularities of the rollers and races wear away to smooth. This is when you should go back in and re-torque to the second torque, where drag can slightly be felt. If this is done correctly, the typical tapered bearing will last for thousands upon thousands of hours of movement. Since it takes about 1000 hours of run time to wear out a typical SOHC4 engine, the bearings will usually beat that.

[mcswny]

Yep, the bearings should be "set" to 40 in-lbs, then backed off 1/4 turn, then snugged back down. After about 1000 miles, you will need to repeat, as the races will settle a bit into the steering head. Then it will stay in tune, for like 40k miles.

Curious, is there a special torque wrench for a spanner to get it to 40 in-lbs, or is this just based off of years and years of "feel"?

With all [new] tapered bearings, you can get very close with their "feel". As you tighten them, move them back & forth about 10-30 degrees, and there will be a point where they suddenly increase in friction. This is the torque where the sheet metal cage just distorted itself to align all the rollers it has, at once: then back off from this point, and then snug back down to where friction just starts again (on new ones). The first friction point is around 35-50 in-lbs for this "set", the latter is the point where the full length of the rollers just contacts the full face of the races.

After an initial run-in period (like on car wheels), the surfaces irregularities of the rollers and races wear away to smooth. This is when you should go back in and re-torque to the second torque, where drag can slightly be felt. If this is done correctly, the typical tapered bearing will last for thousands upon thousands of hours of movement. Since it takes about 1000 hours of run time to wear out a typical SOHC4 engine, the bearings will usually beat that.

Great, thanks Mark. I did as your book said over the winter. and retightened a few weeks ago. I'll probably triple check again this weekend.