P38 Diff & VCU Wos... Plus Angry at Indie!

Alright,

Just got back from a Indie who, at the moment, will not be named in case I am wrong but I don't think I am...

When I got the P38, the rear diff was fooked, so had it replaced by these guys for a 4-pin (supplied by them) and was never quite happy with it as sure if continued to rumble between 35-55 on over run, but, having returned it they initially told me it was fine and it was the VCU at fault.

Now this panicked me as my previous P38 diff exploded due to this issue, however, I had not experienced the 'skipping' on the rear wheels when doing a circle or the ABS going nuts as the wheels were moving at different speeds, in my new P38...

Anyways, I bought a new VCU, went to fit, but thought I'd just check it and so did this:

[ame=http://www.youtube.com/watch?v=XddClDAIfXw&sns=em]Range Rover P38 (P38a) Viscous Coupling (VCU) Test - YouTube[/ame]

As you can see, all was ok... So returned VCU (although had to pay restocking charge) went back to Indie and let them know. So they look again, agree VCU ok and say the front diff is knackered as input flange was very hot, hence this is the noise!

At this point I had already been talking to another Indie as have been loosing faith and so I had them confirm that the front diff had gone. They also said the rear rumbling may just be the bearings, however, it was hard to tell due to the front wine (which had started to develop).

So, not too worried as I was confident the front diff needed replacing, I have carried on regardless until December (2 months later) where the rumbling became more profound and when just slowly rolling under the autobox's own motion, you can hear the rear diff 'working'.*

Due to this, I thought I'd check the oil in the diff and it was black/metallic so off back to my 'new' indie to confirm that, yes, the 'new' diff was defo broken, which he subsequently did, so I could return with this info to the original Indie.

So, back to original Indie, asked to check, they did and confirmed diff gone and they would replace. This, unfortunately took them 3 weeks to get round to doing, as they 'couldn't get another 4-pin' (rubbish) so I offered to get one on their behalf and hey-presto, they managed to get one and I had her in there today.

However, I went to pick her up as agreed at 4.30-5pm and they were just STARTING to dismantle but said the VCU is frozen solid and that is why the diff has gone??? I challenged this and they 'showed me' testing it which was very different to how I've seen it down before (all wheels off deck, wrench on front prop and rear prop..)

Further to this and something I am fuming about, is that they had a 2-pin diff sitting next to my RR ready to put in and when I questioned this, they stared at it and said 'oh yeah'... My thought is that they were going to stick a 2-pin in and claim it was a 4-pin hence I am wondering what was put in her before...

Anyways, I told them to put it back together and left, very angry and thinking I have peed all the money I paid them to do the job in the first place up the wall...

So, I'm off outside in a bit to re-check the VCU using the method shown in he video, so my question is, is*this the correct 100% method to check the VCU (just to cover my arse)?

I have already booked the RR in with the other indie to check he VCU again next week, so at least I have a professional opinion.

Many thanks in advance from a very angry and frustrated Diehard

That way is fine or you can drop the front prop and put a lever on the flange as I think it say's in RAVE. Putting a wrench on the prop itself sounds like a recipe for destruction of the prop.

if all four wheels are off the ground you should be able to turn front prop to test v/c but you would need to hold rear to be sure v/c turned,i use both methods ,ut mostly with v/c off the vehicle ,4 pin diff is only stronger in the diff itself and isnt any stronger than 2 pin in bearings and crown wheel and pinion,the more effort and speed you put into turning v/c the stiffer it gets,if yours is much stiffer than should be it will strain diff bearings etc,p38 diffs are off an age now where its more than likely they have wear in bearings ,and if reconditioned if pattern bearings used a couple of months would be a long time to last,regular oil changes are best for diffs most that i see dont get that

cheers for the info guys, ill go have an another shot at her in the next hour or so, but I really don't believe its gone...

Right all done:

https://www.youtube.com/watch?v=KH3hw0xOtxo&feature=youtube_gdata_player

I don't think its 'siezed to 'fook' as the mechanic said... actually a lot feerer than last time, although it was a lot colder today and it got stiffer the more I turned it.

was original rear diff actually buggered or front

Rear mate, well and truely gone but the front started to whine from 35-0MPH and diff input flange is cooking.

so they stuck duff rear diff in

That is what I think as still 'rumbly' straight after but defo no grinding at first, but they blaming it on vicous coupling being, 'siezed'

v/c isnt seized and they dont unseize themselves,if rebuilt one **** bearings or poor used which most used ones are

Yep I agree, the diff they supplied was a 'good'second hand unit for £150 plus fitting. Obviously it was nakkered and I doubt its even a 4-pin after what they were trying to pull today!

Guys does anyone have the page number for the VCU test on Rave? iPad is a bugger when searching PDFs...

Had a quick look on RAVE, couldn't see it.

Found this on Ashcroft Transmissions site though:

RRC, Workshop Manual, Section 41 Transfer Gearbox, Overhaul, Dismantle, Inspection & Overhaul.

You can either do this test on the bench or in the car with the handbrake on and one front wheel lifted.

Viscous unit - rolling resistance Bench check NOTE: Testing should be carried out in an ambient of 20 �C.

1.Secure the output shaft ...

2.Apply a clockwise torque of 27 Nm to the (front propshaft) output flange nut. If no resistance to turn is felt, unit requires replacing.

3.If resistance to turn is felt, apply a clockwise torque of 20Nm to the (front propshaft) output flange nut for 1 minute, this should result in a rotation of approximately 25� - 30�. If no rotation or a greater force is required, unit requires replacing.

27 Nm = 20 lbf-ft 20 Nm = 15 lbf-ft

Cheers mate

Not tried with a torque wrench yet but I know it's not seized at least... Best get onto trading standards I think to pursue getting a new diff :doh:

Right, got the RR booked in at my trusted Indie on Wednesday to confirm either way the condition of the VCU ready for the next steps.

Regardless of the outcome, I need two new diffs, anyone know which other LRs have the same diffs? Just to broaden my searches

Just a quick check, on Ashcroft's site it says:

"As a confirming check, put transfer case in "neutral", handbrake on, jack up one front wheel and try to turn it, it should turn slowly with resistance, if locked solid the viscous coupling is seized, and will need changing before any damage to the diffs or CV joints occur."

I didn't do the fuse thing and just put the gearbox in "neutral" does this mean I am doing it wrong or would it make no difference? I cannot (in my head) think what in the transfer box would take up any slack so must be the VCU?

I like to cover all aces

makes no difference at all ,just means your not turning gear box out put shaft ,since v/c isnt seized ,poor diff fittted,

jamesmartin said:

makes no difference at all ,just means your not turning gear box out put shaft ,since v/c isnt seized ,poor diff fittted,

Click to expand...

Cheers mate, will get something written from my Indie to confirm too and go from there.

Whilst I'm on it, always been dead set on 4-pin diffs due to strength, however, I don't tow, don't seriously off road and although I do do a lot of miles, this is mainly motorway and not caning it, so, are 4-pins really needed?

2-pins from emmotts are half the price of 4s...

4 pin only have stronger diff ,crown wheel and pinion and bearings are still the same on 2 pin

jamesmartin said:

4 pin only have stronger diff ,crown wheel and pinion and bearings are still the same on 2 pin

Click to expand...

So in laymens terms, unless I'm going hard and spinning wheels (I.e. getting jiggy off road) then I should be good with 2pin?