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FFCobra Owner
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Discussion Starter · #1 ·
OK....here is something I just found out, and wonder how many are experiencing the same.
My rear hubs...continue, over time, to loosen,....not because the nut is loosening..but because the compression of the whole bearing assembly as such!! My builder has called the racing guys...and they confirmed...'yep, bad design,but this happens.....and we just keep tightening them down..and after time...after compressed enough..will most likely stop"
this seems nuts!! But Lang and I agree.....that now i need to keep a wrench and socket to keep tabs on it...any of you get this?
It appears to happen with high output motors and IRS. 550 hp and 550 torque. Still, seems weird!
fred. z
 

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My totally uninformed guess is that maybe the bearings were not pressed "home" initially. Or, you got a couple of bad bearings that are slowly eating themselves.
 

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Fred:
Sounds like your running IRS.
That nut needs something like 250 lbs/ft of torque to properly tighten and it actually does compress the bearings.
The inner race on my bearing units are made in two pieces so it is imperative to tighten them to spec.
How did you install it,and at what torque?
Paul M.
 

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Originally posted by Cannonball Cobra:
Fred:
Sounds like your running IRS.
That nut needs something like 250 lbs/ft of torque to properly tighten and it actually does compress the bearings.
Paul M.
Also the nut must be new and not reused.
 

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FFCobra Owner
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Discussion Starter · #5 ·
thanks guys......but we actually addressed all your issues....first of all, it has happened 3 time....going on 4!!
yes, we used new nuts! and yes...it has been to spec....ie: 250lbs of torq. but, these race guys told Langley.....it is common!! not unusal...and that they go thru it all the time with heavy hp and torq on IRS cObras.
soooooo just curious if anyone else, has had this situation? I am not arguing that it sucks...but if it is not to be so uncommon....then so be it!!!!!! Yes. the story is that the bearings and enclosures are compressing....and will continue to compress until no more compression is available..then should stop.
news tome.........but hey. not my pay grade!!
fred z
 

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Happens to me. I have a long wrench handle (cheater bar) and a big socket. I tighten the nut every so often as part of routin checks. Sometimes it's a little lose, most times it's not.
 

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I have never seen the nuts you are referring to, but is there some sort of formed washer in the stack up of parts getting clamped? 440C bearing material will not creep, but any metal that can be easily formed, bent 90 degrees without breaking, will creep and the nut will loose its clamping force without moving. If there is something you bend over after you tighten the nut as a retainer, throw it away and get a hardened washer. Use another method to keep the nut positively retained like a second nut on top of the first.
 

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Hi there, i thighten mine using a five lug spanner i made out of 1/2" steel with a shaped handle on it that fits inside a heavy gauge pipe about 2 feet long this nutted up on the hub with the wheel nuts. With the car on stands and with all in place the tube should touch the ground. Then using a 1" drive socket and bar with pipe extention and my 85kg at a given length on the bar, locktite on the nut i have no problems at all. Hope this helps.
Laurie
 

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The bearings were not pressed all the way in. I have several thousand miles on many IRS cars and only once had the nut come loose, why, because the bearing was not all the way pressed. It takes a 20 ton press to drive them home. We have a fixture for it. HTH, Cheers Richard.
 

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I have 5000 miles now. I torqued them to 250 using a brand new nut from Max. I have checked them but never found them loose. I had an 03 cobra that I drove the snot out of. They never came loose ether.
 

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I´ve talked to Ford-Tech about this since my nuts came loose after hitting the throttle some times.
The hub is pressed into the knuckle with very little power, you can easily (like I did) press it in the vise in the workshop at home. However, my nuts were replaced and tightened really hard (don´t know the exact spec I used) but they don´t come off anymore.

My suggestion is to replace the knuckle-bearings, buy a new set of one-time-use-nuts, loctite the nuts and tighten them to the 250-spec.

I had major concerns about this, but I made sure of the above and everything works fine now. Approx 400HP, but can´t see that 500 would have them come off.

Is it happening on both sides? Old cars had different tightening-turns (threaded left / right) so that the nut would self-tighten when driving. Mine happened most on drivers side, but also on just 1/4 of a turn on passenger.
PM me if you think I can help...
Peter
 

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FFCobra Owner
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Discussion Starter · #12 ·
peter........i think the relation of the driver and passenger is about the same as yours........thanks....I am going to email this to my builder.......will let you know if I need more........much thanks...to everyone so far.
fred z
 

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I would inspect to be sure no damage occured to bearing assembly form running when nuts were loose. Can't imagine how the retaining nut could back off. If it can't back off,then the bearings must be moving.
 

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Quote Supercharged Pete "I´ve talked to Ford-Tech about this since my nuts came loose after hitting the throttle some times."

That's funny right there. I don't care who you are!
 

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FFCobra Owner
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Discussion Starter · #15 ·
I think rather than the nut loosening....the bearings are compressing.....like some said..but now with some better understanding.....we have already ordered new bearings.and nut....and will most likely fix it right.......if not i will be the fastest 3 wheeler in town!!!
fred.
 
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