Ital live axle oil overfill quantity

[Gridgway]

Hi all, just putting my live axle Caterham back together and need to fill the rear diff.  It has been refurbed with a Quaife ATB fitted so it's going to be empty of oil.

How much does it need?  Do I fill to the filler level then put an amount more in from the breather hole, or just put a certain amount in from there?

The Graham Sykes document says "overfill to the tune of 2-2.5 pints"  I assume that's the total amount rather than the "extra", but I'm not sure!

Cheers

Graham

[Jonathan Kay]

Assembly Guides give it as 0.7 L and as 1.0 L.

Fill to the hole or as instructed by the supplier of the diff.

Jonathan

[Gridgway]

Thanks Jonathan, but the paper from Graham Sykes, says to overfill which I understand is required in the live axle.  Just confirming what that specifically means.

Cheers Graham

[Jonathan Kay]

2.0 Imperial pints = 1.14 L.
2.5 Imperial pints = 1.42 L.

Could you add the document, please.

Jonathan

[Golf Juliet Tango]

Graham:- Ital or English axle?

[Gridgway]

It's Ital

[rkeywood]

The quantity mentioned is the extra over the normal fill. That takes you pretty much to the breather - the normal way was to take the breather out and simply fill to there. I have the same setup as you and always done this without problem.

Reply to #4 
the Graham Sykes paper is in the Low Flying archive - March '93

[Gridgway]

#7 wow, actually pretty much full then!

[Jonathan Kay]

"the Graham Sykes paper is in the Low Flying archive - March '93"

Thankyou

"The Ital Axle Debate", includes:

Jonathan

[rkeywood]

Reply to #8

TBH I've never measured how much I've used. I'd been racing with the diff for a couple years before the Sykes article was published - the advice I got from the axle builder was to get as much in as I could! Re-reading the article, the pint is the extra over I was thinking of. I'd see how much you can get in the fill hole, then put the extra pint in the breather and see what the total comes to  and where the level is.

[Gridgway]

Today I foubd some previous diff oil in the garage in addition to the 2l I bought.  So I had 2.8l in total.  It all went in.  1l to fill up to the filler hole, then another 1.8l in through the breather.

Do we think that's enough even though I could get a little more in?

[rkeywood]

1.8l down the breather is too much. I'd go back to the 1 litre to the plug and a pint down the breather. I've just looked at the oil left on the shelf and looks like I put about 1.6 litre in mine when last filled. A friend suggested, probably quite rightly, that I'm not waiting for the oil drain away from the axle tube and it settles a lot lower than the breather. He also reminded me that Caterham used to fit a second filler above the strengthening plate to allow overfill which would set a level just over half way up the axle. There's a later article in Low Flying (Nov 2017) which suggests not to overfill for road use only to avoid oil sitting in the axle tube all the time.

[Gridgway]

I am filling from scratch as it's had a complete refurb and ATB fitted, so would expect it to take a lot.

From the instructions in the article, if I drain down to the filler plug level, I should put 2pts or just over a litre back in through the breather.

[Gridgway]

Now I am really confused.  I dipped the oil level from the breather hole and it's 5cm down from there.  That puts the level at about the top of the reinforcing plate welded on the back.  Or just over halof way up the diff.

I had assumed with my 1.0l to the level hole and a further 1.8l I'd be very close to the top.

The level is about 3cm higher than the bottom of the filler hole.

Is there such a thing as being overfilled?  What is detrimental with that?

[rkeywood]

The risk is leakage past the seals onto brakes. It sounds to me like you're at the level of the additional filler Caterham fitted.

[Gridgway]

Thanks!

I've taken a bit out, so I have followed the instructions.  Over-filled by 2.5 pts!  I'll not worry about it now!