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Discussion Topic:
Right rear wheel hop above 55 mph
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supereal |
09-05-2014 @ 2:23 PM
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Senior
Posts: 6819
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Glad you solved it, Steve. When I had problems with Coker tires, they tried to tell me it was my fault as I didn't know how to install them. The shop that installed them has been in business since 1930, and really know their stuff. After I unloaded on Coker, they did replace the two faulty tires, and all was well. I know they are a good company, but no one should have to arm wrestle with a surly phone rep. I wonder if Corky Coker knows about this problem?
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cliftford |
09-05-2014 @ 8:18 AM
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Senior
Posts: 845
Joined: Jan 2014
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Glad you solved yout problem. All of this proves two things. 1. Two{or 3 or 4] heads are better than one. 2. On line diagnosing is far from an excact science. It is more like a trial and error process. Good luck, Gene
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len47merc |
09-05-2014 @ 7:53 AM
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Posts: 1165
Joined: Oct 2013
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You all deserve the credit - glad we all solved my problem.
Steve
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TomO |
09-05-2014 @ 6:42 AM
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Senior
Posts: 7250
Joined: Oct 2009
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Glad you solved your problem.
Tom
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len47merc |
09-04-2014 @ 11:46 AM
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Posts: 1165
Joined: Oct 2013
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UPDATE - Well, looks like a combination of issues at play here. First of all though, the rear bearings and axle/hub chases were checked and mic'd and found to be true, without pitting and within acceptable tolerance. Also, the axle was validated as not being cracked and/or bent. The bearings, bearing surfaces and axle were all checked with a micrometer and dial indicator. Thanks Gene and supereal for your thoughts here - I should've been more robust earlier in the restoration and it was good to take the time to validate this (glad no issue was found as well). So here we go. Tom & carcrazy, balancing the wheel on the car solved ~75% of the problem, so apparently when I had the drums turned this resulted in an out-of-balance condition on the right rear only (all drums are the originals). The right rear tire by itself was balanced, but back on the car and spun up to 70-80 mph produced a more than noticeable vibration. After balancing on the car it is very smooth now. Thanks Tom & carcrazy. Secondly, when installing the tires originally the installer verified the lateral and radial run-out as within spec. Both tires now on the front ARE within spec, but both now on the rear are outside of the spec limits per Coker. Disappointed in the original installer after finding this out and depending upon their information so am moving back to my old-schooler for the future on these bias-plys. Supereal - you pegged this aspect - thanks. Rotated all tires front-to-back and back-to-front and now the rear axle, with tires/wheels now balanced on the vehicle, is rock solid/dead still at 55-60 mph and even up to a short burst to 75 mph, so the on-car balancing combined with round(er) tires solved it. Now for the tires with radial run-out out-of-spec... Coker is standing behind their product and are sending me two new tires based on the out-of-spec condition for both. Very frustrating to say the least. Thanks to you all for your great advice and support.
Steve
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len47merc |
09-01-2014 @ 4:55 PM
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Posts: 1165
Joined: Oct 2013
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Thanks supereal - will give this and the other recommendations all thorough examinations if the on-car balancing of the wheel/hub/drum does not address the issue. I have both a dial indicator and an original hub puller so this should be relatively easy if these next steps prove necessary. Update later this week.
Steve
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supereal |
09-01-2014 @ 2:19 PM
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Posts: 6819
Joined: Oct 2009
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Thanks for the update. I suppose it is possible that the right rear axle end is slightly bent. I'd pull the drum and hub and give the end of the keyway a close look, and check it with a dial indicator. Generally, if the axle has been stressed, there will be a crack in that area. My '47 will run at 70 and above in overdrive, but I seldom exceed 50-60 on the highway unless necessary. I used to get wheel tramp with my old tires, as they flat spotted even after sitting overnight. The new Coker bias plies did away with the problem.
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len47merc |
09-01-2014 @ 5:48 AM
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Agree with your logic supereal and appreciate your peeling the layers off the onion here. To clarify further, both this set of tires and the previous set, which were new as well, begin/began hopping at ~57 mph on the right rear only, even after swapping right-to-left and front-to-back. So now I've two sets of new tires exhibiting the same behavior on the same right rear location regardless of which of 6-8 tires were put on the right rear. (Btw - Coker replaced the first set under warranty for a completely unrelated issue) My search for a brake drum & hub balancer have not yielded a source so as noted earlier the plan is to have the entire wheel/hub/drum balanced on the car later this week. Hoping for a positive result with this effort. Thanks again supereal and to you all for your knowledge and support here.
Steve
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supereal |
08-31-2014 @ 4:21 PM
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Posts: 6819
Joined: Oct 2009
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Balancing on a machine usually detects only tires that are seriously affected. If the problem is in the carcass, such as the belts below the tread, it isn't always possible to find. This was the problem with my Coker tires. It isn't always known that an out of round or out of balance tire will affect the vehicle on either the front or back position. As you mention the tires are new, it seems obvious the problem is tires, if the "hopping" didn't occur with the old tires. A very small amount of radial deviation, not the tires, but the measurement between the hub and the tread, can produce the speed related vibration, as will a small out of balance . We see this when we balance flywheels and drive shafts at our machine shop.
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len47merc |
08-30-2014 @ 5:46 AM
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Thanks supereal - as noted in the first post above these new bias-ply tires have been checked during balancing, rechecked during trouble-shooting and validated for lateral and radial run out under pressure all around and are well within spec. Rotating the tires side-to-side and front-to-back does not affect wheel hop on the right rear beginning at ~57 mph. Am taking the car next week to have the right rear wheel/hub/drum balanced on the car by an old-schooler with the equipment to do it. Will update then.
Steve
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