Winchester stub axles - UPDATE and Questions!!!

[AcecaRacer]

Hi gang -
   
   I have been off the forum for a while and sadly off the track due to work needs.  Must pay the bills!
   
   Anyway, I raced my ACECA for the first time in a year.  It was great to be back on the track again.  Oh how I have missed her.
   
   Now for the update...
   
   The good news - the Winchester stub axles along with the fix for keeping the bolt from unscrewing worked a charm.
   
   The bad news - Part 1
   Firstly, during my first practice session, in a long left hand carousel, I heard a bit of a "bang" followed by a pronounced rubbing sound of my backing plate on my left rear drum.  Not good.  I pulled into the hot pit and got out and gave the left rear a tug. WOW! significant movement.  So, I limped back to my garage and put her up on jacks.  We pulled the spinner off and THE TOP 3/4 INCHES OF THE BOLT HOLDING THE STUB AXLE TO THE HUB FELL ONTO THE GROUND!!! Yes, that's right, a 5/8" x 1 1/2" grade 5 hardened bolt SNAPPED in the hub.
   After 3 hours of hitting every hardware and automotive store in a 40 mile radius, I finally found a Grade 8 replacement for the sheared bolt. We replaced both rear bolts to be safe. Problem solved!  Or so I thought.  Well, at least that problem was solved.  However, my mechanic and I were (and still are) completely baffled by the bolt shearing.  We cannot understand how it could have happened.  Perhaps the next bit may help...
   
   The Bad News Part II -
   After running in my afternoon practice session, I noticed I was having backing plate rubbing sounds again.  I finished the session and put the car back on jacks again. This time BOTH rear wheels were now loose!  However, the bolts had not moved at all due to their retaining plates. Yet, after removing the retaining plates each bolt could be turned at least 1/2 turn before snugging up again.  No, the bolts had not stretched. The only thing we could conclude was that the wheel bearings were compressing in some way...not good either. But, at least we were able to snug them up again and get ready for the race the next day...off to the pub.
   
   The bad news part III -
   The next morning I went out for a 15 minute warm up session in advance of the afternoon race.  5 minutes in, the rubbing started again in earnest.  I finished the session and went in.  Yup, up on the stands she went.  This time the bolts were tight!  But the wheels were still very wobbly.  Game over.  I had no interest in losing a wheel in the race.  We were done...
   The only thing we could surmise without a complete tear down was that the bearings were shot.  BTW, these bearings only had one session on them and were the same type I had used for the previous 3 years.
   One MAJOR difference was that for this weekend, I was using AVON's instead of Dunlops.  I knocked 5 seconds off of my best laps ever with these tyres. Their grip was vastly superior.  So, the thought was that this increased grip/load was just too much for the bearings to handle.  However, I had run them once before with the stock stub axles without issue. So we are concerned that the design of the Winchester stubs may not be supporting the bearings correctly.
   
   Now it's over to you...!
    - What do you think happened?  Why did the bolt shear?
   - What are my options for different bearing choices?
   - Upright choices?
   
   I look forward to a healthy discussion!
   
   Cheers,
   Rob

[Klassik Metall]

Hi Rob,
   
   I also purchased a pair of these stub axles last year for a 2.6 Ace I'm building. Upon receiving the axles I was also unimpressed by the roll played by the use of the (very loose) retaining bolt and spring washer as designed. After I read your initial findings, which confirmed my fears I returned the axles to Nigel so he could get a new pair made up that incorporated the threaded section of the originals. Last week after several months of waiting the new shafts arrived! These now have a 3/4''UNF male thread with a split pinned castle nut similar to the original 3/4'' BSF setup.
   
   However,while these new hubs will unquestionably be able to handle more torque than the original taper and key design the setting of the hub position and bearing preload still remains absolutely critical.
   
   The hub depth and preload in the new design is set by the use of a thick splined washer that locates on a very small shoulder at the base of the splines. My feeling is that this is the  week link in this area and maybe where your problems stem from. Possibly when your hubs have loosened in the past it has caused these washers to fret on the axles and so increase the clearance. This increased clearance could be enough to unload the bearings leading to slight axial movement, which in short order would cause an outer wheel bearing failure.
   
   Another factor is that of the outer wheel bearings, the original type not having been available for some years. The current bearings have fewer balls and irrespective of the loading specifications from the bearing manufacturers there has to be some ''real world'' difference here. A possible upgrade here would be the use of angular contact bearings but I suspect a suitable replacement with the same dimensions may not be available.
   
   Overall I think that Nigel's new axles are a step in the right direction and probably fine for normal road usage but are as yet marginal in racing applications due to the increased cornering/grip loadings. I guess that for now at least Nigel's customers will remain his R&D department!
   
   All the best
   Luke.
   
   PS. Did you solve your door lock issues?

[Klassik Metall]

Just to add to my original posting,why not upgrade to a MKI Cobra rear setup,
   After all Thames Ditton went through all this years ago and their answer was a redesign utilising a much improved taper roller setup.
   
   I guess maybe you have to retain the rear drum brakes for your racing series?
   
   Just a thought!

[Robin A Woolmer]

Gerry Hawkridge & I have been in discussion regarding the design of the Ace & Aceca rear axle design & the proposed modifications available & concluded that a more substantial re-design was essential to achieve a reliable modification, AC had two subsequent axle designs both for the Greyhound & then the Cobra that are clearly better designed, however both required the uprights to be modified/changed to achieve this!
   Gerry agreed to therefor re-design the Ace & Aceca axle assemblies incorporating the Taper Bearing Design as in the FIA Cobra axles which have proven reliable & capable of transmitting the high torques now required, the upright modifications are completed together with the new axle design both of which are in the final phases of completion.
   We believe this will offer a complete solution to the problems with a well proven design, unfortunately it does require new uprights, axles & bearings etc. But is expected to be a permanent solution which will save considerable frustration & costs in the long run!
   
   
   Robin

[AcecaRacer]

Thanks to all for your quick replies.
   
   I look forward to more responses.
   
   Robin, regarding the newly designed rear end assembly, when do you expect availability and can you put a finger on the cost?
   
   Luke, yes I managed to solve my door closure issue.  It was a combination of issues.  Door gap seal that was too thick thus precluding the star assembly from rotating completely to catch and also a serious need for cleaning and lube.
   
   All that being said, I forgot to latch my door properly when out on my practice run and it did come open!  Fortunately, I had a bungee cord keeping it from flying all the way open.  The local track photographer caught a great picture of it.  I will post if I can figure out how.
   
   Thanks again...
   Rob

[Robin A Woolmer]

Rob
   This is  Hawk Cars modification package, have asked Gerry Hawkridge for the timing & costs etc for you & will post it shortly. Gerry also has forged front Stub axles which have an upgraded bearing specification.
   
   Robin

[Robin A Woolmer]

Rob
   An update from Gerry, he expects to have the conversion package of uprights, hubs, axles, bearings & seals etc. available for February 2014 shipment at a cost of just under £1500 per side so change out of £3000 a car set.
   
   regards
   
   Robin

[AcecaRacer]

Thanks Robin.  I would love to get more info on this.  I assume it will not affect the rear drums etc?
   Rob

[Robin A Woolmer]

Rob
   Gerry & I looked into the AC Company axle designs & the other offerings in the market & concluded that the best approach was to use the learning curve AC went through & therefor use the well proven Cobra Axle design as a no compromise solution, as Gerry has been getting into authentic AC Ace Replica's also that he supplies Cobra Axles then the new Ace/Aceca axle should be similar to the Cobra but accommodate the Drum Brakes fitted to these cars, that is what is happening.
   Clearly Gerry can give you more information on the project so it would be best for you to contact him for the follow through, my interest is mainly in AC Weller engines but am making an authentic Ace type replica for my engines, which therefor causes me to be interested in the design of the Ace parts etc.
   Robin

[jrlucke]

Rob, great photo of the Aceca with the door ajar on Tams's website:
   
   http://www.tamsoldracecarsite.net/csl0001SaturdayHomepage.html
   
   He doesn't have the links for the larger images completed yet, give him a day or so.
   
   Is the #66 1960 Bristol BEX1213???
   
   John