Lotus Elan

Front Hub bearing spacers for Elan/Plus 2

PostPost by: ajoasika » Thu Aug 04, 2016 4:08 pm

Dear all,
I am looking into getting some hub bearing spacers made, to fit the Elan/Plus 2 stub axle, as well as the later (stronger) Spitfire/GT6 stub axles. The theory is that because the stub axle can flex slightly under loads, the disc tends to knock back the pads, so that when you come to brake, you have to pump the pedal to get the pads back into position. By effectively stiffening the stub axle with a tubular spacer, this doesn't happen. This spacer is shimmed such that the bearing clearance is correct with the hub nut tight, as opposed to the floating castle nut and split pin method. A company called Revington make these for TRs for about ?75/pair, http://www.revingtontr.com/product/rtr3 ... el-bearing, and MGB's have them as standard. I don't however see any for the smaller Triumph uprights that we used.
So would anyone be interested in a pair of these? Similar price.
The attached photo is of the 39mm gap between the inner races that the spacer would fill.

Mark Hollands
Louth
01507 355867
[email protected]" target="_blank" target="_blank
Attachments
hub-bearings-2.jpg and
Hub bearings
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PostPost by: CBUEB1771 » Thu Aug 04, 2016 6:54 pm

Mark - Excellent idea, I have missed this feature from my MGB days. These stiffeners also keep the inner races from moving and therefore wearing on the axles. I would be interested in a set for my +2 and probably also a set for the smaller Herald axes used on the Elite and Elan. I am in the US but I imagine that would not be an issue for Remington.
Russ
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PostPost by: RichardHawkins » Fri Aug 05, 2016 11:51 am

Mark

I think I have seen these spacers marketed by one of the Triumph specialists such as Moss or Rimmer.

Richard Hawkins

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PostPost by: rgh0 » Fri Aug 05, 2016 12:05 pm

I would be concerned about these spacers for a number of reasons

1. They do not allow the outer bearing to be adjusted to get the correct preload on both bearings as it locks the distance between the two bearings inner races
2. i also doubt they do much to stiffen the axle as they cannot develop an real shear load at their ends which is required for bending stiffness.
3. I also have never had pad knock off problems even in extreme racing conditions with properly adjusted bearings. and I use the smaller bolt on stub axle also not the larger Knock on stub axles

Knock off in racing is typically caused by the hub getting hot and expanding and the preload on the bearings being lost. You need to run the bearings end float a little tighter than factory spec when cold to accommodate this. If your using alloy hubs the problem is worse and you need to preload the bearings even more when cold.


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PostPost by: CBUEB1771 » Fri Aug 05, 2016 2:33 pm

Rohan,
I don't understand a couple of your points, unusual because you are always spot-on. The front bearings are not preloaded, they always have end-float which will vary a bit with temperature as you indicate. The proposed kit, which is identical to what BMC installed in MGBs in period, allows a full range of end-float adjustment via shims. I agree that the increase in axle stiffness is compromised a bit by the cylindrical "column" around the OD of the axle being comprised of two inner bearing races, shims and the tube itself, rather than being one piece. Nonetheless having the tube loaded in compression around the outside of the axle does add measurable bending stiffness to the complete assembly. That was BMC stated reason for doing this to the MGB (stated to mechanics in training). I agree with you completely that brake pad knock-back is normally caused by excessive end-float in the wheel bearings.
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PostPost by: rgh0 » Sat Aug 06, 2016 12:00 am

Hi Russ
Sorry :oops:
I used the term "preload" loosely to mean the adjustment of the tapered rollers to the required specification. In the Elans front stub axle case this means adjustment to a specified end float. For many back to back tapered roller applications a specified degree of compressive load on the bearings is required not end float


Whether it adds much stiffness to the overall assembly will depend on the tube wall thickness and diameter and the amount of compression you put on it with the axle nut. With enough axle nut torque you will get some stiffness increase like you say. This may help on the heavier MGB front end but I have not seen it needed on an Elan in practice.

But it cant hurt provided its shimmed correctly

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PostPost by: CBUEB1771 » Sun Aug 07, 2016 3:12 am

Rohan,
Understood, we are all on the same page then!
Russ
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