Measuring trueness and runout on wheels

[georgesgiralt]

Hello Guys,
Since I've my nice wheel stand for balancing the wheels, I play with it.
I've seen in the factory manual that our cast wheels are considered done when the trueness is above 0.9 mm at the rim and the run out above 0.5 mm at the rim.Without a tire on  the wheel.
As there are no lateral stop on the position of the wheel axle on my stand, I bet I will be making a fowl of myself measuring a wheel with so precise figures.
So i would like to find a way to stop every lateral motion in order to be sure  my clock indicator shows the real run out  of the wheel. Any ideas ?

[Tony Smith]

First, put your dial gauge back in its box, this is not a situation where it is of any practical use to you.

When I first started building bicycle wheels I spent significant time "improving" the truing stand I bought, and yes, that included making mounts for dial gauges so I could measure radial and lateral excursion.

But you don't need it.

I read a very interesting book called "Wheel Building" by Roger Musson. Now Roger has built more bicycle and motorcycle wheels than I have had hot breakfasts and he knows a thing or two. As a result I removed the dial gauge mounts and replaced them with moveable strips of black cardboard (i happened to have black, ordinary cardboard or the plastic spatulas they give away with various putty/paint products will be ideal).

I then positioned the truing stand so that the strongest light source was on the other side of the stand from me. To my initial amazement, any hops or wobbles in the wheel immediately stand out like dog's testicles.  Not only do they stand out, you can rotate the wheel back and note the point of greatest excursion and mark it if you desire.

I have now built hundreds of bicycle wheels and quite a few motorcycle wheels and the only measuring tool I use whilst building the wheel is a spoke tension gauge, and that only because I am tone deaf.

I have not attempted to true up cast wheels, although I know how to do it in theory using a lathe face plate and a hydraulic "Porta-power" type ram, but I don't have a big enough lathe at present and besides, a local engineer reckons he can straighten most salvageable alloy wheels for less than $50 if no welding or painting is required.

But to return to your question - you do not need to know the precise measurement of the excursion, only that it exists and your Mk1 eyeball can do that to a surprising degree of precision. If you are planning on marking the high/low spots and "adjusting" them with blocks of wood and a 5~10lb mallet I actually think that would work for minor excursions. Please let us know how you go.

[georgesgiralt]

Hello Tony,
My question was not well asked.
I had 2 front wheels. Said to be dead by the dealer years ago.
I went to the local BMW guru with  my 2 wheels and he  said one was s salvageable, and the other was not.
I dumped one of them.
Now, with my balancing and truing stand, I put the salvaged one   on it and I see some wobble...
So I would like to know if it is within specs or if I dumped the wrong one...
The specs from BMW are below the mm so need some precision to measure properly.

[Tony Smith]

Hello Tony,
My question was not well asked.

The specs from BMW are below the mm so need some precision to measure properly.

I'm sorry, I may not have considered my answer all that well. However, my answer does largely remain the same - The light behind the card method will show you the amount of excursion, if you cannot estimate it and do not have a dial gauge, then feeler gauges inserted between the card and the wheel will let you measure it.


Under 3mm and I'd just use the wheel, more than that and I'd send it to someone who could roll it true for me.

[georgesgiralt]

Well, the wheel is way under 3 mm ! I measured around 1 mm (but this measurement is difficult because the dial indicator pushes the wheel laterally and cam/may push the axe on the bearings of the support. So I'm happy ;-) I dumped the correct wheel.
The BMW Guru said that he could have trued the other one but the defect was too big to be safely trued. This is why he declared it done.  It is a pity because it was the original without the reinforcements, and they look better than the later.

[Tony Smith]

The BMW Guru said that he could have trued the other one but the defect was too big to be safely trued. This is why he declared it done.  It is a pity because it was the original without the reinforcements, and they look better than the later.

Ah, so 19" rims then. It is amazing considering how far back that wheel recall was, just how many of the early 19" rims are still out there. I was looking at a bike only yesterday still proudly wearing one.

[georgesgiralt]

No, Tony, 18" front R65 wheel. At first the design was thin. After the 19" problem they also "improved" the 18". Better safe than sorry. But no recall for us poor R65 owners.
This rim was on the bike in 1982 when she left Berlin to Toulouse.

[Tony Smith]

No, Tony, 18" front R65 wheel. At first the design was thin. After the 19" problem they also "improved" the 18". Better safe than sorry. But no recall for us poor R65 owners.
This rim was on the bike in 1982 when she left Berlin to Toulouse.

Where are they different please? My understanding is that the R65 wheels were unaltered between 1979 and 1984, I am lucky enough to be able to walk downstairs and compare, side by side, a 11979 R65 and a 1984 edition. I cannot detect any difference in the front wheels - where should I be looking?

[georgesgiralt]

Every arm is thicker from the center. They added a small vertical wall at every "spoke". It is easy to see if you have both wheels in front of you but not too obtrusive.
I should have taken a picture or two before dumping it.

[georgesgiralt]

Hello Tony,
Searching a fuel cap for my tanks on a French ads site like Craiglist, I've found picture of a front R65 wheel proving my say ;-)
Here they are :

[Tony Smith]

Hello Tony,
Searching a fuel cap for my tanks on a French ads site like Craiglist, I've found picture of a front R65 wheel proving my say ;-)
Here they are :

Thank you for that. I will more closely examine m y own wheels

[georgesgiralt]

Here is the  picture of a 18" front wheel of the second design pattern... The difference is quite obvious  even if the picture is a little blurred..

[Barry]

Well I've just learnt something new.

I knew BMW didn't include the 18" wheels in the recall and assumed that was because they have a different number of spokes to the 19".  But I didn't know they had modified and strengthened them anyway.  From an aesthetic point of view I must say they did a better job of it than the they did with the 19" wheels.  

[georgesgiralt]

Well, they had a  failure on an 19" wheel  which forced them to recall a a  lot of wheels. I bet they strengthened the 19 and 18 "  wheels and pray no  accident will happen on an 18" wheel which did not (well  no one reported...and claimed on §BMW responsibility... ) So they  did not  recall the 18" . So we have some  still laying  around. Are they safe ? I can't say. Are they looking good ? Yes!

[Tony Smith]

Here is the  picture of a 18" front wheel of the second design pattern... The difference is quite obvious  even if the picture is a little blurred..

I am sorry to say that unless I actually see the measurement stamp that is, as far as I am concerned, a 19: wheel. Remember I have owned a 1978 R100RS since new so I went through the whole recall saga.

Now to turn to R65 wheels, it has always been my understanding that the R65 wheels were pretty much the same from 1979 to 1985. I am in a fairly good position to confirm that given that my wife has owned her R65/80 since brand new in 1979.

I own a 1984 R65 which I am assured was unmolested from new until it ventilated a piston in 1995 (and I have the service log book that was meticulously maintained until 1992 when the previous owner started using a non-BMW specialist for servicing (the the obvious results when the excessive valve guide wear was undetected).


Lastly I have a wheel sold to me as coming from 1982 R65, the seller kindly sent me photos of the whole bike at the time to prove it had not been in a wreck.

So, let's look at my wheels.

1979 L&R, 1982 L&R and lastly 1984 L&R.

Now if you look closely you can spot detail differences, particularly in the 1984 wheel where the mould tooling was clearly getting a bit worn, I suspect that wheel spent a long time on the re-work line having the excess mould flash removed, however aside from that the 1982 and 1984 wheels are pretty much identical.
 
The 1979 wheel exhibits some interesting differences, and I may say was better made than either of the two newer wheels (its bent by the way but being sent to a repairer very soon and after hydro-blasting and painting will be put back on the 1979 bike....

There are no reinforcing webs on any of them as per the 19" post recall wheel and I dare say that no genuine R65 front wheel ever had the reinforcing webs.