Thread: Is this a 2a diff?

Hi Sam,
One backing plate is correct for a 2A, the other with the bottom adjuster is from a Series 1 (later 107" or 109") or a Series 2 109".
I would be interested in swapping a correct one with you as I am looking for the earlier bottom adjuster type. I have some NOS 2A backing plates (not sure which side) and most of the other brake bits.
Drums are the same but other parts including shoes are different.
regards,
Bob

Thanks Bob - yeah the 2a one is the original diff - and the other is Series 1 or 2 as you say.

Happy to swap components - but does that mean I can still use the diff just swap the backing plate? - or is everything different?

I have the two complete setups front and rear which I bought for my resto - but didnt knkow what it was.

Thanks

Sam

Backing plate just bolts on and is interchangeable (with the bits attached to it).

John

So John can I swap the backing plates and use this diff on my 2a? Are the earlier duffs inferior?
Should I just persevere and restore the original diffs that came with the car?

Hi Sam,

The casings should be same. That said just check the width between the backing plates. A late Series 1 and a Series 2 LWB fully floating axle differential fitted with these 11" backing plates should be the same width as your 2A assembly - there will be a reinforcements welded underneath the casing, particularly between the differential and the passenger side spring perch.
If it has the reinforcements the same as your casing then it should fit correctly. Nothing wrong with the diffs.

I will get a chance to find the plates, etc I have on Tuesday.
Generally the only things that wear are the snail cam adjusters for the brake shoes - you can get repair kits for these for your backing plates. The bottom adjuster type shoes do not have posts for the adjusters to press against.

Bob

S 1 axles are about 1 1/2 narrower than S2 .That's why people fit spacers ,so they can use S2 half shafts.
Reinforced fully floating rear axles are standard on S1 109 LWB.
All S1 (except 107 station wagons )have got the springs under the chassis rails,S2 LWB have got them on outriggers.S1 and S2 LWB rear axles are not interchangeable without modifications. W

Originally Posted by B.S.F.Nut

S 1 axles are about 1 1/2 narrower than S2 .That's why people fit spacers ,so they can use S2 half shafts.
Reinforced fully floating rear axles are standard on S1 109 LWB.
All S1 (except 107 station wagons )have got the springs under the chassis rails,S2 LWB have got them on outriggers.S1 and S2 LWB rear axles are not interchangeable without modifications. W

Doh, you are right about the spring perches on 107" and 109" LWB Series 1 being under the chassis and and not on outriggers like the 107" Series 1 Station Wagons, the Series 2 and 2A. The earlier casing is shorter, the axles are shorter and the track is narrower - therefore not interchangeable with a 2A.

The 2A has the wider casing and longer and more readily available axles (half-shafts) referred to in your post that were fitted using spacers at the outer end of fully floating Series 1 and 2 axle assemblies between the hub and the driving flange.

If the distance between the backing plates is the same on both assemblies then someone has fitted the bottom adjuster brake system to a later wider differential casing. It was quite commonly done in the 1970s.

We need a photo of the whole assembly (to show the spring perch position) and a measurement of the Wheel Mounting Face to Wheel Mounting Face for both differential assemblies.

Bob