S2 rear hub castle nut

[maxcar]

I am having trouble with my S2 rear end outer drive shaft nuts. Especially the left one , which keeps undoing itself. This is quite common, I understand. Since the D-washer has rotated and doesn't look like a "D" anymore, I would like to try something else. I would like to drill a small hole through the driveshaft and use a split pin with a castle nut in conjunction with Loctite. Does this sound like a good idea and does anyone know which size the nut is and where to find such a castle nut?

[LotusJoe]

I'm pretty sure this modification has been done before. I think it is a practical solution.

[cal44]

First, are you getting the proper torque number on the nut? Factory numbers please.

If it keeps loosening then yes, drill a hole and either use a split pin or Cotter pin.  The Porsche 356 uses Cotter pins and I never had one let go.

Mike

[maxcar]

First, are you getting the proper torque number on the nut? Factory numbers please.

Good call, that's essential information.

EDIT: I misunderstood your question. I thought you meant the torque rating of the nut, which is also something to consider. But yes, they were tightened to the factory torque number.

[EuropaTC]

Mine's a TC but it's the same basic problem. I was told that when assembling the outer hub spacer, hub, D washer & nut to use copious amounts of Loctite (the wide gap product, I forget the number off hand) and tighten it up properly. You know you have enough when it oozes out of the assembly as you tighten up.

Of course this means that to remove it you need to heat the nut & hub with a propane torch to break down the Loctite before it will move and even then you will need hub pullers, but I've never had one loosen since.

Brian

[maxcar]

Brian, have you done any track driving without the hubs loosening? And where did you buy your D-washers? I bought mine from Banks and the D-shaped hole was distorted from it rotating around the axle.

[EuropaTC]

Hi,
Nope, I don't do track sessions but a few of the other guys on this forum do and include a few serious racers, so I guess they might be able to comment.  Using Loctite has kept it in place until the bearings or UJs need replacing though, I've done the job a few times now and removing the hubs is tough even after heating - think in terms of a length of pipe over the socket handle !

The D washer shouldn't round off though, so something is wrong.  I seem to recall the central section was thicker (1/8" ?) and it would take some serious force to round that off. I'll check the workshop this morning to see if I've got any spares I can photograph so you can compare.
Brian

[maxcar]

It would be good to know which Loctite you used. 648 seems to be very tough when dismantling, so I'm considering using 270 instead. But the question is if it will do the job. Have you used Loctite on the bearings too? I can imagine that it would make the hassle of removing them a lot worse, since it is hard to use a puller there. What kind of pullers do you people use for the hub and the bearings?

The D washers I used match your description, but the left one didn't stand the torque.

[EuropaTC]

Hi again.

I found 2 old washers, one is a Lotus OEM, the other one I must have made at some point by taking the thicker central section & spot brazing a home made lock tab on. The thick section is approx 3mm, the thinner, bendable section probably 1mm or even less ?  Neither are in a good state for accurate measurements ( ) but at least you can see how they compare with yours.

The loctite grades have changed since I bought my bottle, which is probably 50ml size. It is a thick green liquid designed for large gap filling, not your conventional thread locking varieties and I think it's the gap filling properties which seals everything up tight which are the important features. (that's a guess) There was a comment on another thread here about "fretting" which seems a reasonable theory as to why Lotus had this problem with the hub/spline assemblies loosening in practice, and one of the claims that Loctite make is to reduce fretting problems.

But it is very hard work to remove it, you'll never pull off the hub without using a torch to degrade the loctite before pulling the hub.  When I got my car the problem was well known and I have a vague memory that Lotus issued the instructions for using Loctite but I'm not sure.  My info came from Chris Foulds who was/is a fairly well respected guy in this area and gave me the lowdown the first time I bought the parts from him. The other thing he was hot on was to check the middle spacer tube, in fact he told me to buy new ones with the bearings (which I did).

What do the racers amongst us do ?  Anything different ?

Brian

edit to add - incidentally there's nothing wrong with your original suggestion of a castellated nut & pin, a very practical solution. I'm just curious as to why it's needed because Lotus stuck with the basic design throughout the life of the car.

[maxcar]

Thank you for a detailed reply. I will certainly look into using Loctite.

Does anyone know the size of the hub nuts, then?