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Old 09-06-2015, 07:38 PM   #1
DansBugatti
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Default How much Wheel wobble is acceptable on a 21 inch?

I have just bought a set of 4 wheels with white walls in pretty good condition. But upon mounting them I find that they have between 3/16 to 1/4 inch of wobble from 0-180 degrees of rotation. My concern is that I plan on doing 60-70 mph with this vehicle. I have no Model A experience so I'm asking for good advice. Also, how to fix if it is too much wobble.

Thanks for any help.
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Old 09-06-2015, 07:58 PM   #2
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Default Re: How much Wheel wobble is acceptable on a 21 inch?

That is way too much wobble. I would say 1/8 is about the max especially if you are driving fast.
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Old 09-06-2015, 09:18 PM   #3
ian Simpson
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Default Re: How much Wheel wobble is acceptable on a 21 inch?

Quote:
Originally Posted by DansBugatti View Post
I have just bought a set of 4 wheels with white walls in pretty good condition. But upon mounting them I find that they have between 3/16 to 1/4 inch of wobble from 0-180 degrees of rotation. My concern is that I plan on doing 60-70 mph with this vehicle. I have no Model A experience so I'm asking for good advice. Also, how to fix if it is too much wobble.

Thanks for any help.
If you plan driving at 60-70mph, make sure your life insurance is paid up.
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Old 09-06-2015, 09:26 PM   #4
DansBugatti
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Default Re: How much Wheel wobble is acceptable on a 21 inch?

Thanks for info. Hope I'm posting this right. Anyway I thank you and I'm thinking I will be selling a set of Wheels next spring. This is the first setback I have had with this project. Oh well...
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Old 09-06-2015, 09:40 PM   #5
Charlie Stephens
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Default Re: How much Wheel wobble is acceptable on a 21 inch?

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Originally Posted by DansBugatti View Post
Thanks for info. Hope I'm posting this right. Anyway I thank you and I'm thinking I will be selling a set of Wheels next spring. This is the first setback I have had with this project. Oh well...
How about having them straightened? If you put your general location into your profile or into the post maybe someone would know someone close that could do the work.

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Old 09-06-2015, 09:50 PM   #6
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Default Re: How much Wheel wobble is acceptable on a 21 inch?

I would not use anything over .075 . I have about 20 wheels. Most are under .100. I am going to use Brents way of straightening a set. Setting my goal under .015. Rod
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Old 09-07-2015, 06:26 AM   #7
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Default Re: How much Wheel wobble is acceptable on a 21 inch?

I admire your courage in being willing to go 70 MPH in a car with a limber chassis, no substructure and no roof or roll bar and tires with less than 9 square inches of contact patch. Having said that, the drawings say that 1/8" is acceptable as I recall, but at speed, a more important issue for any amount of run out is the propensity for the large diameter, narrow wheel and tire combination to 'wobble' in and out. Toe in/out should be kept to a minimum as this WILL be an issue at that speed at the front wheels

Consider this as well. If there is 1/8" run out at each tire: If all four tires are in alignment so that ALL four tires are 'pointed' to the right at the same time, what do you imagine that might feel like at the steering wheel as the cars travels at high speed?

As always, These are just the thoughts from an old man.

Best wishes, and good luck.
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Old 09-07-2015, 07:53 AM   #8
Mitch//pa
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Default Re: How much Wheel wobble is acceptable on a 21 inch?

computer balance all 4 wheels putting the weights on both sides for optimal results.. that should eliminate any vibrations..
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Old 09-07-2015, 08:26 AM   #9
Chris in CT
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Default Re: How much Wheel wobble is acceptable on a 21 inch?

Hi Dan,
I see you are new to the barn as well as new to the model A hobby. Welcome! its great to have you aboard.
The above is all good advice. There are a couple of folks who can do wheel straightening, and it might be a good idea to send your wheels one of them. I think there is a guy on the barn - Dave in Minnesota - who does it, but you'll have to look him up.
One thing, while a Model A well tuned can do 60 to 70 mph, I would like to caution you to re-think whether you really want to use this car at those speeds on a regular basis. A couple of years ago, when I was testing a new counter-slung crankshaft, I had my '29 roadster up to 70 mph on the well-paved route 22 in upstate New York. The car's frame, steering, and brakes were all AAA, but I had the feeling that if I hit a acorn in the road, me and the car would be history. I think I can speak for most of us when I say that many of us are the most comfortable when touring at 50 - 55 mph. Personally, I like my scenic drives at 30 - 35. Happy Motoring!
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Old 09-07-2015, 08:37 AM   #10
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Default Re: How much Wheel wobble is acceptable on a 21 inch?

1/8" is the most, but, not for a 70 mph vehicle. But, then a stock Model A is no 70 mph vehicle.
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Old 09-07-2015, 09:01 AM   #11
Kevin in NJ
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Default Re: How much Wheel wobble is acceptable on a 21 inch?

First off 70 MPH is the top end for some original cars. Though truely that is high.

Lets think about the Model A wheels.

First off define what wobbles? You seem to indicate it is the rubber with the issue.

As I recall Ford allowed 1/8" on the rims. I put Goodyear tires on my rims with less then 1/8" of out. When I spun them I could not see any wobble. The Goodyears seem to be of very good quality. Some tires are not as good and people have reported some new tires with excessive out of rounds.

I personally set up a from spindle wth lightly oiled bearings on the bench. I mounted the rim with the tire and let it find the heavy spot. Then I moved the tire around on the rim to find the best natural balance point. I would suggest that you try doing something like that with your wheels as it is cheap and offers a lot of gain. I also plan to put some of the stuff for balancing the wheel in the tubes.

You need to understand the A has a lot of unsprung weight. This will absorb more of the vibrations of out of round and out of balance conditions. You will have to take your car out and see if you even have an issue before you spend a lot of resources correcting the issues. I also have put the better balanced wheels on the front and the ones that were more out on the rear.
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Old 09-07-2015, 09:18 AM   #12
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Default Re: How much Wheel wobble is acceptable on a 21 inch?

First off I want to say thank you for all the helpful post. I was referred to this site from someone I contacted off Craigslist in hope for info on this subject matter. The chassis for this car is a 67VW (yea, poor mans kit car). I have put a Subaru ea82 with 90 HP in it. The car will weigh about 1,200 when done. Mostly I plan on doing about 30-55 with it but traffic around here doesn't care what you are driving, they want 60-65 in a 50. I plan to take it to shows and parades for fun and occasional road trips up the north shore of Mn. I think the frame and suspension can handle the speed. I will have to research and check on straightening the wheels. The original Bugatti has nearly same dimension wheels but are of a much higher standard of accuracy/build/strength etc...

I guess my best bet would be using the VW wheels or some after market bolt on. I was just trying to get as close to original as possible.

If anyone knows a guy in Mn or Northern Wi who straightens them let me know. Thanks for the info on MnDan (I think it was) in a previous post. I will check in on that.

Safety is my first priority. No sense in mangling myself over a cool look

I will also complete my profile when time permits.

Last edited by DansBugatti; 09-07-2015 at 09:26 AM. Reason: Clarify intent.
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Old 09-07-2015, 09:52 AM   #13
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Default Re: How much Wheel wobble is acceptable on a 21 inch?

To define what wobbles.... I put a ruler/screwdriver/whatever on the backside of the wheel and rotate the wheel. Under perfect settings the tip of the screwdriver touching the wheel should not move away or start scraping the wheel at all. On one of my wheels I get nearly a 1/4 inch difference. The tire of course follows what the wheel does.

2nd wheel is about 3/16, last two I checked were around 1/8 or less.
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Old 09-07-2015, 11:05 AM   #14
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Default Re: How much Wheel wobble is acceptable on a 21 inch?

With minimal search on the net, you will find the process of spoke shrinking the wheel to true them. Works well, simple and not brain surgery.
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Old 09-07-2015, 03:31 PM   #15
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Default Re: How much Wheel wobble is acceptable on a 21 inch?

You can get brand new powder coated and balanced 21" wheels from Coker Tire. Thats what I did for the two front wheels on my 29 tudor. I am using three good originals for the rear and spare.
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Old 09-07-2015, 03:33 PM   #16
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Default Re: How much Wheel wobble is acceptable on a 21 inch?

Will, I never said I wanted to run 70mph. Rod
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Old 09-07-2015, 03:45 PM   #17
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Default Re: How much Wheel wobble is acceptable on a 21 inch?

Do a search , wire wheel truing. it shows you how to heat shrink spokes to straighten wire wheels.
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Old 09-07-2015, 06:21 PM   #18
Dave in MN
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Default Re: How much Wheel wobble is acceptable on a 21 inch?

I have a write-up on my website that describes straightening Model A wheels by spoke shrinking. Look for: Wheel Wobble Reduction by Spoke shrinking on the DYI Help page.
my website: www.durableperformance.net
Good Day!
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Old 09-07-2015, 09:48 PM   #19
Kevin in NJ
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Default Re: How much Wheel wobble is acceptable on a 21 inch?

If you are talking about the wobble of the tire then stop right here, do not straghten the wheel!!!!!!

Tires can be out of round or just formed wrong. You can put some tires on perfectly round rims and you will get wobble. Some brands are just horrible. If you want to get rid of the tire variations then you will need to make the rubber round or change the tires. As I already pointed out, you might minimize the problems by moving the tire on the rim. You also might not have the bead set right.

In the end, you may find the car runs fine with what you have now or chassis set up issues might cause problems that could be confused with out of round tires.

I recommend you first break the beads of the bad tires and try rotating the tire on the rim to get a better fit. It is a lot of work, but cheap and possibly effective. Do not forget to get the wheels balanced or add the balancing beads (balancing beads might be a better option).
Also try running the car with the tires with your best set up. It may run fine and you may be chasing a non-problem.
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Old 09-11-2015, 12:31 AM   #20
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Default Re: How much Wheel wobble is acceptable on a 21 inch?

I trued up a set of 6 19" wheels recently. A couple of them were out up to 3/8" and they still had straight spokes. For those two, I mounted them on an of junk axle and I put a 4 X 4 against the rim where it was standing proud. I then bumped the high spot with a 15 pound sledge hammer until it measured true. I was amazed how easily the wheel moved to true with a little hammer work. Checking the wheels after straightening for cracks or other flaws proved them to be now perfect for the powder coat man. They came back from him looking brand new. He only charged me $75 each to do them. He shot peaned them instead of sand blasting them before powder coating them. The wheels that I had to shrink the spokes came out nice too. Before shrinking the spokes, those particular spokes were already bent. I had to shrink them to get them to stay straight. Les Schwab Tire is where I dropped the wheels off and they sent them out to the powder coat man in Oregon.
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