1970 2+2 E Type diff unit

Downunda · Post by **Downunda** » Mon May 07, 2012 5:02 pm

Can anyone confirm for me please if the diff in my 1970 2+2 E Type is limited slip diff or not.

4 (orA)HU 004-25
LE/S 1.C
30280

Stamped on
C70 C
00
5984

Tag bolted on 43/14

Thanks
Ian

GSR 54D · Post by **GSR 54D** » Mon May 07, 2012 5:48 pm

One method to find out is to jack both rear wheels off the ground and rotate one wheel and if the other turns in the same direction it is a limited slip diff. If the other rotates opposite way it is not.

John H

PeterCrespin · Post by **PeterCrespin** » Mon May 07, 2012 9:20 pm

There should be another tag saying PL for Powr-Lok and the test described works provided the transmission is in neutral or the diff is off the car.

It sounds as if it may be an open diff which would be one of the fairly rare later cars so equipped. Do you have any knowledge as to whether the diff is original or whether tha car was originally an American car? Please report back if it is open or LSD.

Pete

Downunda · Post by **Downunda** » Tue May 08, 2012 9:56 am

Thanks for the posts.

The car was delivered direct to Australia, the suspension cage is out of the car, the oil has been drained and when I turn one wheel the main drive shaft turns. I am not sure if the diff is original.

Ian

vee12eman · Post by **vee12eman** » Wed May 09, 2012 8:31 am

Ian,

I think that without the tags you will only find out by actually turning the shafts and seeing what happens. I know you have done this, but do it again and this time, prevent the diff input shaft from turning. Do this by putting a couple of longish bolts into the input flange holes, then put a bar between them to stop rotation. It would be even better to get a bar (perhaps a piece of angle iron) drill two holes at one end to take bolts which again go into the diff input flange.

With the diff input flange now held either by a willing helper or jamming against the ground, turn one of the wheels - oh yes, of course make sure both are off the ground and free to turn. If the other wheel rotates in the opposite direction, you have a normal diff, if it turns in the same direction, you have a Limited slip diff. That is the conclusive test.

Without that test, you will not know, since tags can get lost or even be added by unscrupulous owners and with a car of uncertain history, anything can happen.

Regards,

Simon.

PeterCrespin · Post by **PeterCrespin** » Thu May 10, 2012 10:36 pm

vee12eman wrote:Ian,

I think that without the tags you will only find out by actually turning the shafts and seeing what happens. I know you have done this, but do it again and this time, prevent the diff input shaft from turning.

With the diff input flange now held either by a willing helper or jamming against the ground, turn one of the wheels - oh yes, of course make sure both are off the ground and free to turn. If the other wheel rotates in the opposite direction, you have a normal diff, if it turns in the same direction, you have a Limited slip diff. That is the conclusive test.

Not true. The input has to be free to rotate. Otherwise the contralateral wheel would always turn the opposite way. The only difference between open and LSD in that test is that an LSD would require you to overcome the clutch packs to turn the wheel. These are sometimes weak so you might hardly notice the resistance and mistakenly think you had an open diff when the wheel turned the opposite direction. By contrast, with the input free to rotate (i.e. trans in neutral) even a weak set of clutches should make the opposite wheel of an LSD turn the same direction.

Downunda · Post by **Downunda** » Fri May 11, 2012 9:39 am

When I had the input clamped the hubs turned in the opposite direction. Now I no longer have the clamp on the input shaft I can turn ether shaft and the opposite side will rotate in the opposite direction. So it looks like I have a normal diff.

Thanks for the help
Ian

PeterCrespin · Post by **PeterCrespin** » Fri May 11, 2012 4:48 pm

Depends what you mean by normal, Ian. It's clearly a limited slip going by your report - which is normal for an E-type but not for most cars.

If you clamp the input shaft the opposite wheel has to counter-rotate regardless of diff type. So it is a completely pointless test for checking anything other than a totally seized or locked diff.

Turned out well for you anyhow, thanks for confirming.

Pete

Downunda · Post by **Downunda** » Fri May 11, 2012 10:25 pm

Thanks guys,

My reason for this post is a follow up on a previous post where I asked what oils to use in the engine, gearbox and diff. I received some good feedback but I became a bit unsure when it came to the diff unit due to whether it was limited slip or not.

http://etypeuk.com/forum/viewtopic.php? ... highlight=

So maybe I went about this the wrong way and should have continued with the original post but my real concern is should I use Limslip 90 (or similar).

From information I have received it appears safe to say it will be a limited slip diff of some sort, and I will have to use oil with a limited slip additive.

Please let me know if this is incorrect.

Thanks for the help
Ian

PeterCrespin · Post by **PeterCrespin** » Sun May 13, 2012 7:52 am

It's an LSD, so you are not wrong.

Look for an oil suitable for clutched limited slip differentials. Locking differentials that use dogs instead of clutches don't need special oil AFAIK, but the Jag Salisbury 4HA Powr-Lok LSD does. If you can't find a special LSD oil, use normal diff oil but leave enough room for a dose of additive as per the manufacturer's instructions.

Pete

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1970 2+2 E Type diff unit

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