Lotus Elan

Fitting Rear Hub bearings?

PostPost by: vincereynard » Sun Feb 24, 2019 9:06 pm

I should get my strut bits back this week - so -
Could someone point me to a thread discussing bearing / shaft fitting please?

Both bearing, then the shaft? Or rear bearing / shaft then front bearing?
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PostPost by: john.p.clegg » Sun Feb 24, 2019 9:33 pm

Have you trued up the ears on the shafts....too late when you find the disc doesn't run true.

John :wink:
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PostPost by: vincereynard » Sun Feb 24, 2019 10:42 pm

john.p.clegg wrote:Have you trued up the ears on the shafts....too late when you find the disc doesn't run true.

John :wink:


According to the man, crack tested, key slot modded and shafts spun in a lathe to check. One can only hope it's true!
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PostPost by: rgh0 » Mon Feb 25, 2019 1:18 pm

Its an easy :roll: 3 step process to fit the rear bearings and shaft in the hub

1. Mount the inner bearing on the shaft not forgetting the dirt shield . A long tubular drift on the inner race in a press makes it easy to do that but it can be done with a small drift and hammer working around the inner race. Then fit the shaft circlip.

2 Then press the shaft and inner bearing into the housing. Again a press and a three fingered tubular drift that clears the spider arms to press on the outer race to do that makes it easy but a small drift and hammer working around the outer race is practical also. Then fit the circlip to fix the bearing and outer shield in place

3. Finally press the outer bearing onto the shaft and into the housing. This is the most challenging as you are press fitting both the inner and outer races at the same time. i find it best if you warm the alloy housing with a heat gun to open up the clearance and then press on the inner bearing race.while supporting the rear of the shaft in its centre not on the arms to avoid bending the arms. if the outer race is not moving freely into the housing tap it gently with a drift as you press the inner race onto the shaft this then avoids over stressing the bearing itself. Again it can be done with a press and tubular drift on the inner race or with a small drift and hammer There is a lot of "feel" in this last step to make sure the bearing slips into place without damage.

A shop press makes it easier as outlined but you need the tubular drifts as mentioned which are not hard to make from suitable pipe, i have also done it successfully many times with suitable small diameter 8 mm rod as a drift and carefully working around as I am driving the appropriate inner or outer race with a hammer

cheers
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PostPost by: david.g.chapman » Mon Feb 25, 2019 6:59 pm

I changed my rear bearings a few weeks ago using a short length of scaffold tube crushed in a vice to form an oval. The oval shape just cleared the bearing shaft on its minor axis, and just fitted inside the bearing housing on its major axis.

In this way you can contact the inner and outer bearing races at the same time. Good for drifting in the outer bearing as a last step. As you drift the bearing in, rotate the drift to apply force around the bearing, as the oval contacts each bearing race in two restricted areas.

Best of luck,

Dave Chapman.
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PostPost by: RichardHawkins » Mon Feb 25, 2019 10:14 pm

Vince,

I have just helped a friend by turning the three eared flange true, 90 degrees to the axis. I did the same to my own shafts. One was correct, the other still needed a 0.0005" shim to get the disc running true, better than 0.002" at the outer diameter of the disc.

In my view the disc run out should be checked and corrected before the drive shafts and rotaflex joints are installed, as it is much easier to remove the disc to fit a shim if required.

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PostPost by: The Veg » Tue Feb 26, 2019 2:27 am

What's the best way to get the old bearings out? I've got some that have resisted all attempts to remove even after using the heat gun to the point that all of the carrier was too hot to touch.
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PostPost by: miked » Tue Feb 26, 2019 8:23 am

Getting old bearings and shaft out!
Decent welders type gloves. Slide hammer made out of old shaft with 3 eared spider. Bolt to offending shaft. With all circlips removed and areas cleaned, apply heat with torch over bearing cases. When nice and hot and sizzling send slide hammers weight to end. This has never failed.
Do however true spider ears up as vigorous use could potentially add to any out of tolerence of spider ear trueness. Saying that most are not true before you start with previous rough handling. Will photograph my hammer when i go out later.
Also some other useful parts that Rohan has decribed.
This saves hitting the shaft from the threaded end even if using soft metal drift to protect.
Cheers Mike
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PostPost by: rgh0 » Tue Feb 26, 2019 9:00 am

The Veg wrote:What's the best way to get the old bearings out? I've got some that have resisted all attempts to remove even after using the heat gun to the point that all of the carrier was too hot to touch.


when trying to remove the old shaft and bearings.

1. Remove circlip on inside of bearing carrier and clean up the area and make sure the dust shield is free

2. Then support the housing on its inner edge in a press and press from the outside with a socket over the threaded section that bears on the shaft shoulder ( the tapered hub has previously been removed of course). warming the housing ensure the inner bearing comes out with minimum damage to the alloy. A slide hammer on the inner end arms or a hammer and suitable drift from the outer end can achieve the same in most cases and if done carefully can avoid damage

3. If the shaft and inner bearing does not move it means that the outer bearing inner race is seized on the shaft. Some heat and freeze cycles using a heat gun and Loctite "freeze and release" will normal free this up enough for the shaft to come out of the inner race.

4. If it still will not come out and you 're sick of heating and cooling it and don't want to use any more force due to fears the alloy carrier will be damaged then you need to cut a groove in the inner race with a Dremel almost all the way through and then split with a chisel to release it from the shaft.

In the end if people assembled it other people can pull it apart again :lol:

cheers
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PostPost by: vincereynard » Tue Feb 26, 2019 9:49 am

Many thanks for the replies.

I shall add all these pearls of wisdom to my workshop manual.

It looks fairly simple according to that! :)
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PostPost by: vincereynard » Tue Feb 26, 2019 10:33 am

RichardHawkins wrote:Vince,

I have just helped a friend by turning the three eared flange true, 90 degrees to the axis. I did the same to my own shafts. One was correct, the other still needed a 0.0005" shim to get the disc running true, better than 0.002" at the outer diameter of the disc.

In my view the disc run out should be checked and corrected before the drive shafts and rotaflex joints are installed, as it is much easier to remove the disc to fit a shim if required.

Richard Hawkins


Interesting , which shims do you use?
I was considering mounting the assembled strut in a vice or similar. Fitting the disc and checking it by spinning the hub. Having marked the disc / shaft so it would go back in the same place. Is this the sort of action you meant?

It did occur that the brake caliper mounting on the hub could also be out of true!
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PostPost by: RichardHawkins » Tue Feb 26, 2019 7:31 pm

Vince,

That was what I did, held the strut assembly in a vice, and used a dial test indicator.

The shims were rather difficult, as I only needed 0.0005" and couldn't find anything in a sensible quantity and price. In the end after searching through my old bits and pieces I found two that were 0.0005" different in thickness, I think they were 0.0025" and 0.003". I installed three shims to get the 0.0005" difference. In hindsight, I may have been more sensible to file the disc or the drive shaft flange as it is such a small error.

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PostPost by: elj221c » Tue Feb 26, 2019 7:58 pm

RichardHawkins wrote:Vince,

That was what I did, held the strut assembly in a vice, and used a dial test indicator.

The shims were rather difficult, as I only needed 0.0005" and couldn't find anything in a sensible quantity and price. In the end after searching through my old bits and pieces I found two that were 0.0005" different in thickness, I think they were 0.0025" and 0.003". I installed three shims to get the 0.0005" difference. In hindsight, I may have been more sensible to file the disc or the drive shaft flange as it is such a small error.

Richard Hawkins

Overthinking it all I feel.
It's a 60's car.
Precision engineering it is not.
I didn't have the means back in the day though now I do and maybe I would use them out of interest but working to such fine tolerances is really not necessary.
Really!
Roy
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PostPost by: vincereynard » Tue Feb 26, 2019 10:27 pm

elj221c wrote:Precision engineering it is not.


I'd noticed! :shock:
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PostPost by: The Veg » Wed Feb 27, 2019 2:04 am

Thanks. I think my easiest option is to take it back to the old racing-mechanic who noticed the duff bearing while welding on the threaded tubes. He was nice enough to pop off the flange for me while he was at it, and figured I could handle the bearing. I've already been on it with a hammer and drift to no avail, and it's far from the first thing on this car that he properly stuck.
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