Daytona rear wheel hub/axle problem

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Timo
Posts: 216
Joined: Thu Apr 13, 2006 8:56 pm
Location: Riverside, California

Daytona rear wheel hub/axle problem

Post by Timo »

Hi,
I posted this on the Daytona-site already, but though that some one here might have experienced something similar:

I'm tackling with this persistent/recurring little problem on a (right) rear wheel/rotor hub and wheel axle shaft.
When I first came across this issue over a year ago, I initially thought it was a wheel bearing problem, as it felt like such when grabbing from the top and bottom of the tire and twisting it back-and-forth (as one would when checking on wheel bearings while the car is on the lift), although I was told by the owner that the rear wheel bearings had been replaced right after he'd bought the car less than couple of years before. After replacing the bearings and few weeks later, car was brought back with a "occasional tapping/thumping noise coming from the rear (?), especially when accelerating during up-hill climbing", I noticed same "looseness" in that same (right) rear wheel and thought that maybe I did something wrong during the first bearing replacement and proceeded to disassemble everything again with extra care. While not seeing anything really wrong, I decided to replace the bearings again, just to be safe and then assembled everything again with extra care. Few days later I was notified, that "the noise" is back and that some other mechanic by now had taken a look at this, but not been able to see any problem(s).

I then offered to take the car in and disassemble the whole rear suspension, to see if anything in it's assembly and/or condition is causing this problem to re-occur. During all this we (owner and I) decided to service/replace/plate/paint/etc all rear suspension components (you know, ..."while you're there"...) and I decided to "throw in" another set(s) of bearings, now for both sides. Now this time, during the final assembly, after everything was together/torqued, the tires/wheel were mounted, the car still on the lift and not yet driven at all, I noticed that the right rear tire/wheel felt loose.
Upon further investigation, I found that the hub/rotor assembly was moving up-and-down on the axle shaft (?) and after multiple times of dis-assembly/assembly I had discovered some possible machining discrepancies in the tolerances between the axle shaft and the hub, including some small "scores" at the inside end of the hub and the shim washer between it and the outer wheel bearing. Also, the axle shaft O.D. (at the "shoulder" by the bearing) and the I.D. of the hub (at the same spot as on the shaft, toward inside end) had approx. .019 (or so ?) "looseness" difference. I didn't disassemble left side for comparison (But I will now !!!)
After testing/correcting these tolerance differences by machining new shims, etc... and assembling everything with extreme care, all seemed nice and tight, even after test drives.

But now, again, the car is back with same problem and while I'm getting ready to disassemble both rear hubs now, I thought of asking if ANY of You out there has experienced anything similar and could perhaps offer some advice/guidance ?

Timo

P.S. I hope my above "explanation" makes sense ?!?
Timo
8339
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Location: Reisterstown, MD
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Re: Daytona rear wheel hub/axle problem

Post by 8339 »

Timo, I have to ask a really stupid question so bear with me. Did you notice any excessive wear on the wheel center hub splines or the splines on the hub from the axle? Depending on how this car was maintained and driven in the past, it's possible no one ever serviced the wheel hubs, cleaned them and then re-lubed them. I've seen a lot of older center hub cars come through where the splines are worn or the knock off outer taper is worn so it won't torque. By the way how much torque do you apply to the wheels? Again, my apology if you've already been through this.


Richard Garre
Radcliffe Motorcar Company
Timo
Posts: 216
Joined: Thu Apr 13, 2006 8:56 pm
Location: Riverside, California

Re: Daytona rear wheel hub/axle problem

Post by Timo »

Richard,
first of all, there's no stupid questions and secondly, thanks for responding. Yes, this car has had well/hard driven life without necessarily strongest emphasis toward maintenance along the way and therefor most its components are perhaps bit more worn than on other Daytonas I've worked on. Heck, during aforementioned rear suspension bushing services on this car I found more than half of the Teflon/nylon (?) coated outer bushing thrust washers assembled backwards and most of their dowel pins missing, etc.
Since my initial posting yesterday and upon further investigation, I believe I have found the problem. After disassembling both rear hubs/rotors from the wheel axles and carefully measuring all related tolerances, i.e. spline depths/dias/widths/etc..., I found quite substantial differences, especially in the inside spline and inner end "shoulder" diameters of the hubs from side to side.The right (culprit) side appears to have much greater tolerances (.018"-.019" vs .0005"-.003") between axle and hub. "Stub" axles seemed to have same spec's (or within .0005") from side to side. So, the bottom line is that the right side axle hub splines and inside "shoulder" are too large, either by mistakenly machined so by factory or it has gotten replaced one tin or another over the years and no one at the time bothered to check it for "matching" tolerances and my "mistake"during these recent efforts was to take it for granted, which I very rarely do with any cars or parts, that it's made right. After all, its a Ferrari made component :wink: :wink: .

As for the wheel tightening, I use torque wrench with sockets (custom designed and made, by yours truly, octagon socket for D.O.T. approved centers or another with reversible insert for three eared centers) and I tighten them to 325-350 ft.lbs.
Timo
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