Input Differential Oil seal

Plus 2 Discussions
1

Hi everyone,
I have just noticed that my rear input diff oil seal has developed an oil leak ? What a pain.

Has anyone replaced this seal with the diff still mounted in the car?

It looks as though the prop will drop down or could be held up out of the way but can you get to the centre nut to remove it.

Also is the centre nut a right hand or left hand thread? And what sort of pressure will I need to exert on it to get it undone?

I remember doing a 105E Ford many years ago and it was an absolute pig to get the nut off.

Look forward to your comments

Thanks

Dave

2

Just a test sorry

3

It might just be possible in situ with the right (custom made) extractors and seal drive tools especially as I can see where you are coming from with removing the diff being pig of a job.

Despite that I’d forget about doing it in the car and learn the joys of how to remove the diff in less than 6 hours without the use of a crowbar, big hammer and foul language

Once out its a 10 minute job to do the seal :wink:

4

Dear Dave
I think the crownwheel and pinion are 105E items in a lotus casing so replacing the seal will no doubt bring back happy memories of having done it all before!
Richard

5

Dave,
Those seals usually fail for good reason. Either the sealing surface is damaged on the flange by the normal fretting wear or the pinion bearings are loose or both. The flange sealing surface can be easily repaired with a Speedi-Sleeve type kit. In any case removing the diff is prudent. Setting the preload on the pinion/flange nut and loading the NEW bearing crush sleeve is something best done on the workbench. What makes this process a mother is the donuts. Bite the bullet and spend the money for the full compliment cv halfshafts and the job can be completed by one person in a day without even breaking into a sweat.

IIRC, it’s a right-handed thread. Best way to tighten that nut is with an air-impact wrench while you grasp the flange. This dampens the forces of the pinion tooth slapping against the crown wheel gear surfaces. The 20 inch/lb load can be measured by hanging a pint of water on a stick which is clamped to the flange slid it out until the pinion rotates and measure the distance (moment). 15 to 20 inches with a pound of weight (pint) will do the trick. It’s more accurate than even a torque wrench can do it if done correctly.

6

Hi Keith,
Well I?ve decided to bite the bullet and remove the diff. I?m just remembering back to the bruised knuckles and the pools of blood on the floor when I last replaced the donuts ? God I must have a screw loose.

Thanks for the tips ? If I find some magical way of doing the repair I will let you all know.

Dave

7

Yep, we all share the pain. Getting intimate with the guts is true Lotusing. :lol: They are built so light-weight they break frequently just like a racecar.

8

?How to replace your input differential oil seal without removing the Diff from your Car?

I am sure that there are many of you that have carried out this work in the parts and will fully understand what I am about to describe ? This is for those who haven?t.

I posted the above question some weeks ago and was told that the only way to replace it would be to remove the diff from the car ? Well knowing this would be like extracting teeth from a lion I decided to leave the diff where it was and give it a go.

Obviously the first thing to do is remove the oil from the diff ? Sounds easy! Well when you can not turn the nut round because its been over tightened then you hit your first problem.

So I jacked the car up at the back and put it on axle stands knowing when I removed the input shaft I would get covered in oil!! Never mind.

The next thing to do is remove the 4 nuts/bolts holding the prop-shaft to the input flange making sure you mark both flanges so that it goes back the same way ? Not sure this is important as they are not balanced as an assembly.

The next thing to do is part the two flanges and then (using half a brick) support the prop-shaft so that it is as high as it can be (the brick should sit on the chassis under the prop-shaft).

The next problem you come across is that you can not see the diff nut and if you could you can not get a spanner onto it!! This is where my dad?s old set of sockets can into its own.

From memory the nut is 15/16th and there is no room to attach a ratchet to it once it is on the nut.
My dad?s socket set had the old type of ratchet, that has the center drive which pushes out either side of the ratchet to change the rotation. Remove this from the ratchet, place it in the socket and then get a small spanner that fits the square drive.

With this you should be in a position to place the socket/boss onto the nut and then undo it!!

Once removed you are then in a position to remove the input flange/shaft. It is at this point your hand, sleeve and arm gets covered in oil. After mopping up the mess the next thing to do is pull out the shaft ? It is at this point you realize that the shaft will not come out as it fouls the prop-shaft ? Oh what joy!!

The next thing to do is unbolt the prop differential torque tie rods from the chassis and pull the bars from the thread (or remove the bolt) so that they are totally free. This will then allow the diff to move on its upper rubber mounts.
You can then either pull the diff down or put a block/wedge above it or use a rope to pull the front end of the diff down.

This will then give you enough space to remove it completely.

Hurrah!!

The next thing to do is remove the old oil seal. Using a suitable length screwdriver, place it in at an angle so that it is behind the seal and then leaver it out.

Clean off the seal surface area and replace the seal with a new one ensuring that it is flush fitting, then reassemble the diff/prop-shaft - Don’t forget to put new oil in the diff - Now theres another story!!!

From start to finish it took me 3 to 4 hours to complete, however this involved a great deal of time considering the issues and coming up with a way around the problem.
Also there were the odd coffee breaks, getting the ball out of the tree for the kids and answering the phone; so you should be able to complete the above in 1to 1? hours without any complications ? What are they I hear you shout.

Looking at the old seal it would appear that time, heat and oil had taken its toll on the seal and after replacing it I have seen no further leaks

I hope this is of assistance and good luck.

9

Hi Dave,
Having rebuilt my diff. on the bench some years ago, I can see a couple
of issues with this.

  1. As the flange nut is usually staked onto the pinion shaft it can be very
    difficult to remove the nut without removing the staking first. Nut also
    requires re-staking on assembly. Not easy with the diff. in the car.

  2. Pinion bearing pre-load is controlled by a collapsible spacer.
    If the flange nut is overtightened on assembly the spacer will collapse
    even further, resulting in excessive bearing pre-load shortening the life
    of the pinion bearings.

Regards,
Peter.

10

I agree with Peter, I have seen a diff that the pinion bearings failed soon after just the seal was replaced,probably because the bearings were overtightened.
You cannot get to the collaspsible spacer without first removing the pinion/bearing which I dont think can be done in place.The manual says if the spacer is collasped when setting it up it should be replaced although I have “panal beated” used ones to expand them.
It is also not possible to set the pinion bearing pre-load with the crown wheel in place because of the crown wheel drag.
If you just replace the seal you can just set the pinion nut back to its original position but this will not quarantee the pre-load, most of the so called leaking seals I have seen were actually leaking down the pinion shaft past the nut because the spacer had lost its tension.
Brian

11

Hey Dave,
Take it easy and you’ll get about 10k miles on it before it starts to leak again.

12

Thanks Guys for your comments.
Keith I would love to get 10K before I have to change it again; at that time I think I will replace the chassis - Its only 36 years old!!

Basically the old oil seal and shaft had sat in the same position for 30 of those years so when I got the car moving again the lip of the seal hand probably fixed itself to the shaft.

In loading the centre nut I basically tightened it to the same point on the thread, which was relatively loose. I used a little mirror and a vernier to check the distance.

Obviously what I did was not textbook stuff but it stopped the leak and stopped the wife from moaning about the oil on the drive! This is the first year the car has been on the road since 1976. I have never driven one before so if I can get a few thousand mile out of her before I have to strip her right down, I will be more than happy.

Thanks

Dave