Twin Special Rear Hub Nut

[rjbaren]

I have just finished my first autocross with the Europa.  Now that it is over I changed the oil and while the rear tires were off the ground I noticed the left rear wheel had some play in it.  I have removed the hub nut and I was able to remove it with a Channel Lock so I don't believe this to be a good situation.  I also noticed the screw that holds the drum to the hub was bent. 
I have watched Serge's video on assembly of the rear hub so I think I understand how things are put together.  I do have another drum to hub screw, but other than cranking the nut to 150 lbs. is there anything else I should do or look for? 
I thought I might like to crank it tight, drive around the block and check it again, and if all is good then add some 290 Loctite.

[jbcollier]

Generally speaking, the nut doesn't "loosen".  It's the spacers collapsing.  It's important to fit hardened spacers when servicing the rear hub bearings.

[rjbaren]

The outer spacers were installed new by the shop that did the engine installation and I believe they came from RD Enterprises.  But, after 500 miles, I dropped the screw in the distributor so the engine and trans were removed.  Now, after removing the hub, the spacer looks pretty good.  Could it be there was no Loctite applied?  I would like to just retorque the nut, and see if the wobble has been removed and hopefully if it has, then remove the nut and hub again and reassemble with Loctite.  Since they engine and trans have been replaced, there has only been another 600 miles put on the car, plus an autocross.  That is why I am thinking the spacer is not the problem.

[BDA]

I believe JR is referring to the spacers between the bearings inside the upright. As he states, the stock spacers are junk. They tend to get beat up. Since the nut is tightened against the bearings and the spacer, when the spacer gets beat up, it’s length is shortened and the nut becomes loose.

It would probably be a good idea to plan on replacing yours with properly hardened spacers of the correct length (very likely available at all the usual suspects). If your problem is something else, you’ll have peace of mind knowing you’ll have the right spacers and that your rear suspension is properly assembled.

[rjbaren]

I understand now.  Either way, I'm going to torque it down tomorrow after I buy the proper socket.  After that I'll see how it feels , and go around the block.  Then I'll decide if I can drive to the shop or have it towed.
Thanks

[EuropaTC]

Now, after removing the hub, the spacer looks pretty good.  Could it be there was no Loctite applied?

and....

That is why I am thinking the spacer is not the problem.

Hmm, from that sentence, does it mean you've just removed the nut/hub after the autocross to check the spacer ? The loctite should be under the hub/axle splines and normally removing the hub needs heat and a puller with some serious pulling.

If you've just undone the nut & the hub has slid off, then there's the first part of the problem, incorrect assembly.

On the spacer issue, I shall don Nomex for the next line....   

I have what I believe are OEM Lotus spacers in my car, or at least they came in a plastic bag with "Lotus" on them.  They've been there since I first changed the rear bearings somewhere around the late 80s.  I've replaced bearings & UJs several times since but it's still on the same spacers & hub nuts. I do check them for fretting but the contact surfaces have always looked good.  YMMV.....

Brian

[Music City Lotus]

I never put Locktite on the splines, but I made spacers that are not oversized like the factory ones. My spacers have the dimension needed to have both wheel bearings fully seated in the hub. The original design has the inner bearing floating in it's seat, which is easy for manufacturing with very loose tolerances, but bad for driving, as the outer bearing takes all the axial loads.
Over 10 years and tons of miles, including track, and no issues with loose nuts or worn bearings.
One caveat: The drive shaft moves into the hub carrier a tiny bit, which can cause some interference. But we are talking about a Millimeter. Nothing a lathe can't take care of.

[jbcollier]

The use of 635 loctite on the splines was added by the factory as the scope of the problems in the field became apparent.  Loctite was added to prevent movement between the splines as this leads to wear.  Also in the manual is that you have to fit new OEM spacers each time the rear hubs are apart.  Current best practice is to fit hardened spacers.

Having the spacers specially made up to fit without play is an excellent idea.

It all starts with carefully evaluating what you have.  Worn, loose-fitting components cannot be made good with loctite.  The splines should be free from wear and the hub a snug fit when the splines are clean and dry.  Any play is unacceptable as the hub may not centre correctly.  Bearings need to be a snug fit into the housing.  They can be sleeved if there is play.

[GavinT]

. . The original design has the inner bearing floating in it's seat, which is easy for manufacturing with very loose tolerances, but bad for driving, as the outer bearing takes all the axial loads.

The axial load path goes like this:
Wheel hub → axle → half-shaft → diff bearings → gearbox & engine mounts → chassis.

Neither of the wheel bearings see axial loads so the floating inner bearing is OK.
The captured outer bearing is sufficient to maintain the position of the axle assembly in the upright.

[E Paul]

I did exactly what you are considering quite a while ago. Don't just retighten the nut as it is likely damaged. I had a wheel nearly come off while driving when the threads failed in the nut. I was able to get onto a grass median and lock the brakes and skid a really long way before really large disaster happened. I found the nut on the side of the road and no threads. Got a ride to a local industrial supply, picked up a nut and got things back on the road. I am a firm believer in the hardened spacers and loctite solution for the splines. I am also using nuts I believe to be higher quality.
It was pretty scary as it happened at highway speed.

[rjbaren]

I bought the socket today so I am ready to try retorquing the hub nut.  I also checked my invoice for the work done at the shop and they replaced both the inner and outer spacers on both sides most likely form RD Enterprises.  George at RD knows the mechanic and feels he's pretty good.  I feel the same way, I feel he is more than exceptional with British cars and they have been racing a Crossflow Europa for the past 20 years and have pretty impressive results in VSCDA.  Also, the time the car was in the shop 600 miles ago, the shop retorqued the driver's side bearing, same side I'm dealing with.  Interestingly enough the washer that get's tabbed over became un-welded so I wondered how it would have locked anything anyway till I realized the one washer became two.  I got this from speaking with RD enterprises on why "One" of the two washers didn't have the D shaped hole in the middle and I then realized that they came apart.  I still have another pair of used washers and I will use one. 
The mechanic said to go ahead a retorque the nut because sometimes it takes two or three times till they stay tight.  I hadn't told him about the washer splitting because I didn't know it at the time.  But I think I have what I need to at least put it back together and see how it assembles and whether I can get the wobble out of the wheel by retorquing it.  After that I think I pay the shop a visit with the washer(s) and get his advice on the Loctite and the next steps if any.

[rjbaren]

Here is a picture of the washer that was bent over the flat of the hub nut.  It became un-welded. I have another used, but in better shape, so I re-torqued the nut.
I checked the passenger side and the washer was in good shape.  Again I was able use my channel lock to undue the nut and the hub on this side also would easily slide off easily by hand.
I re-torqued this nut as well and put the wheel on.  I guess maybe I'll have to check the nut once a month or so.  Other than the hub nuts and hubs easily coming apart everything else seems ok.   

[Music City Lotus]

. . The original design has the inner bearing floating in it's seat, which is easy for manufacturing with very loose tolerances, but bad for driving, as the outer bearing takes all the axial loads.

The axial load path goes like this:
Wheel hub → axle → half-shaft → diff bearings → gearbox & engine mounts → chassis.

Neither of the wheel bearings see axial loads so the floating inner bearing is OK.
The captured outer bearing is sufficient to maintain the position of the axle assembly in the upright.

Gavin, I see what you say. But not completely, or? The lower control arm is leaning onto the hub carrier and gearbox.

[GavinT]

Gavin, I see what you say. But not completely, or? The lower control arm is leaning onto the hub carrier and gearbox.

I'm not quite sure what you mean by "leaning onto the hub carrier and gearbox".

Perhaps it's easier to consider the rear suspension in plan view, thus:

The front trailing arm and the lower link form the two legs of the lower wishbone.
The front trailing arm and the half shaft form the two legs of the upper wishbone.

As a result, the wheel movement is dictated by the two outer pivots of those two logical wishbones - one being the outer bush of the lower link and the other being the outer U-joint on the half shaft.
Kinda have to use the imagination to visualise how these wishbones come about because it's not as obvious as in the front suspension.

Now, squat down behind the car and view the suspension from there.
Imagine the load paths as the car sits on its wheels. It should be seen that the wheels are putting the half shafts in compression by pivoting on the lower link outer bush. The lower link is thus, in tension.

I hope that makes sense, but does it address the question?

[Music City Lotus]

Gavin, the load path is correct, but what is the only connection between the hub carrier and the drive shaft? The wheel bearing. so it does transmit the axial load, not?