/5 front end problems

[Missouri Bob]

I recently bought a 1971 R50/5. The seller mounted new Avon Roadrider mkII tires: 3.25x19 and 4.00x18.

 

Almost immediately, I noticed that the front end wandered from side to side, almost as if the wheel was sliding laterally on the axle. Yesterday, while riding on a curving road, the wander progressed to something more like a low-speed wobble. At that point, I thought the front tire was going flat. It wasn't: 30 psi cold.

 

There is no play in the steering head bearings. They don't feel too tight, either. Sometimes bearing races get pitted, but these don't have that feel.

 

Many years ago, when I put a new front tire on an R60/6, I had a similar experience. No, I don't remember what brand the tire was, but a different tire corrected the problem.

 

Has anyone had had this happen with Avons? How high should I go with pressure? The sidewalls indicate 42 psi max. There are no visible flaws in the tire.

 

Thanks.

 

Bob

[Martyn]

Have you tried increasing the pressures ? That is a cheap & simple first step, that may help.

[Michaelr11]

I have the new MK-II and it tracks really great, good feedback.  I think 30 psi is way too low.  I would try 35/37 f/r.  

[Missouri Bob]

Thanks! That's the information I needed.

 

 

[Hosstage]

What pressure are you running in the rear tire as well?

I have to agree that the front pressure seems pretty low.

Hopefully a simple pressure change solves your issues, good luck, keep us updated on your findings!

[taylor1]

Hopefully tire pressure will help. If not , both Snowbum and Duane Ausherman have good right ups on airhead front fork alignments. I don't have the links, but I'm sure you'll find them when googled .

[dirtrider]

15 hours ago, Missouri Bob said:

I recently bought a 1971 R50/5. The seller mounted new Avon Roadrider mkII tires: 3.25x19 and 4.00x18.

 

Almost immediately, I noticed that the front end wandered from side to side, almost as if the wheel was sliding laterally on the axle. Yesterday, while riding on a curving road, the wander progressed to something more like a low-speed wobble. At that point, I thought the front tire was going flat. It wasn't: 30 psi cold.

 

There is no play in the steering head bearings. They don't feel too tight, either. Sometimes bearing races get pitted, but these don't have that feel.

 

Many years ago, when I put a new front tire on an R60/6, I had a similar experience. No, I don't remember what brand the tire was, but a different tire corrected the problem.

 

Has anyone had had this happen with Avons? How high should I go with pressure? The sidewalls indicate 42 psi max. There are no visible flaws in the tire.

 

Thanks.

 

Bob

Morning Bob 

 

You can try higher tire pressures as a test but that is about all I used to run in my old  50/5 (30 psi ft & 32psi rear). Look in your riders manual. (probably shows 30ft & 30 rear).

 

In any case, get the front end off of the ground then see if you can move the front wheel side to side (if you can then you need to find out why).

 

Also, make sure that your front wheel/tire is pretty well centered between the front forks. (if not then find out why).

 

Then give the front wheel a spin looking for wobble, run-out or vertical run-out. If it looks OK  in all of these then ride it a bit more to scuff the tire in.  

 

If you still have issues after all the above then go back to the tire seller & see if they can spot something amiss (you might have a bad tire with internal ply or cord issues or ?????)

 

 

 

 

[Missouri Bob]

The front wheel doesn't move from side to side. With the front wheel off the ground, I cannot get the fork tubes to move back and forth. The wheel is centered.

 

Unfortunately, the bike did not come with an owner's manual.

 

No chance of getting the tire seller involved. If it's the tire, a replacement will be on me.

 

I'm hoping to ride it later today, with 35 psi in both tires.

[Missouri Bob]

Pumping up both tires to 35 psi, corrected the problem. I should have thought of that before I posted.

 

Anybody in Colorado want a cheap R50/5?

 

Bob