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P38 Differential

11K views 10 replies 6 participants last post by  Awacs 
#1 ·
Hi everyone,
Does anyone have any experience or info on if rear differential is repairable or does the box have to be changed completely?
Today after i visited the service there was a strange noise and when the vehicle was on the lift the noise was very loud at 40-60 mph,a lot of difference compared to front.
Any help would be appreciated,
Thanks
 
#2 ·
The diff is repairable. I had mine rebuilt after breaking a few teeth on the crownwheel.

However, are you sure it's the diff and not a wheel bearing?

Ron
 
#3 ·
Thanks Ron,
The service personnel claim it's non repairable,easy to guess;to sell a box which is around 400 Usd all over the world,but here in Turkey the price is 2000 USD.
I've purchased Timken Hub bearings a few months ago to be installed and today when the car was rolling on the lift there was no noise from hubs at all but only from rear differential.
 
#4 ·
They aren't cheap to rebuild. Mine cost A$1000 for the parts and labour to remove, rebuild, and refit. (Labour rates may be higher here than in Turkey).

And that was a good price.

Any gearbox or diff workshop can rebuild it. it's nothing special.

Ron
 
#5 ·
while the wheels are rolling slowly (on the lift) stop one wheel, dose the rumbing double in speed? if it stays the same it's likely your ring/pinion, $100 from Kam in the UK, the diferential should be fine. It might just be the pinion or carrier bearings.

if the speed doubles it's the diferential or wheel bearings.

Also does the sound seem to match the speed of the wheel, or propshaft?

Any axle/driveline shop can rebuild it, parts might be the only issue. It is a basic axle, made to a different size than anything else to keep it expensive enough to be put in a LR.
 
#6 ·
Hi Dennis,
The sound is as if there is no il in the box at all,a metallic whine,and increases as the speed increases.
More interesting than that is the oil was full,and when checked on the lift it was as clean as when i last changed 6.000 miles before.

I found some of the parts on the Timken's website,and discussed it with the service people today but they still insist on the whole box to be changed,and any rebuilt kit won't give sufficient result.
Silly i know but thats how they make money.
 
#7 ·
AWACS,
with my engineering head on now:
You have a noise (a symptom of a possible fault), but the oil is clean, there is no debris in the diff, and the diff works and you can still drive normally.
So what exactly do the service personnel think is at fault?
What is the fault that requires that a completely new differential rather than a rebuld to replace a faulty, worn or broken part?

I know you have listened to it on the lift at 40-60 mph and it was noisy. I am sure that all our RR are noisy at 40-60mph on the lift. Any car is. If you stood next to the engine whilst is was doing 40-60mph on a rolling road you would think the engine was going to blow up - mechanical things do make noise!

Is it noisy when you are driving it on the road at 40-60mph?

Do you think there is a fault?.

LR diffs whine. P38 are more refined than most but they still do make noise especially on some road surfaces.

My tame LR trained mechanic just looks for the 'affro' of metallic particles when you remove a (magnetic) drain plug or the level of debris that comes out of the Differential at an oil change to assess the state of the differntial. When I have looked at some LR/RR drain plugs I have been horrified but he has reassured me that they have all been normal. This is from a guy that has changed the oil in hundreds and hundreds or LR and RR diffs.

LR differentials are pretty rugged pieces of kit - yes you can break them but if you put a standard car's diffs in a RR you would break them all in the first day of driving.

If I were you I would drain the oil, look for debris, fill with fresh and run for 500 miles then change to synthetic. Things will be a lot quieter then.

Separate question. Why is a new diff so much more expensive in Turkey. Is it import tax? Have you asked a UK parts supplier e.g. paddocks http://www.paddockspares.com/ how much it will cost to ship a new rear diff to you. I think you will be pleasantly surprised.
Rear Diff Assembly - 2 pin - new - RANGE ROVER P38A
TBB100840
£295.00 ex VAT


Rear Diff Assembly - 4 pin - new - RANGE ROVER P38A
TBB100900
£395.00 ex VAT
 
#8 ·
Thanks Gavin for the comments,
Personally i don't think there is anything wrong with it,but there's a lot of metallic noise from the rear differential compared to front at the lift.
More stranger than that is front diff oil was metallic colour,had nothing to do with the original oil colour whats supposed to be and i have no complaint or noise from the front,but rear had an excellent oil,just like new and had that noise,but that noise is not hearable while driving,only on the lift.

I used to drive a Chevrolet T<hoe between 1999-2001 and i had a good GM specialist which i still pass by from time to time,i told him about that noise and his approach was a vehicle on the lift without the roadload will not give efficient result of whining or noise as it sholud on the road.

During this whining and vibration dealer chef du service suggested to replace the shafts with brand new ones to give it a try if vibration disappears,and gone away %50 .
They were also suspicious about the torque converter being out of balance and the flex plate too,so made a 180 degree turn on the flex plate without removing or opening the transmission and that made a dramatic change too.
But i still have the vibe,and will look for a solution next week .

I tried to contact a few suppliers like Paddock and Island 4*4 but no returns from them.
It's not the import tax make s the price triple but just the policy of stealers,and when i get there with parts purchased brand new from ebay theyre kinda this guy is clever to me.
 
#9 ·
While there are areas of the 38A that require specialist knowledge or equipment, I think you proved, by your comments about the GM specialist you know, and perhaps trust more than the Land Rover dealer, that the drive train is an area where you can give work to the GM people.

You say you have tried new drive shafts, with a 50% improvement. By 'drive shaft' you mean the shafts between gearbox and axles? I ask becuase in the UK they are propshafts, in the USA they are drive shafts, and I want to make sure confusion is minimised. (In UK English, drive shafts tend to be the open shafts (gearbox to hub) used for front wheel drive cars, or rear wheel drive cars (differential to hub) with independant suspension. Shafts inside axle tubes, as the 38A's live axles, are termed half shafts, in UK English).

You are chasing a vibration: the first point to look at is the Universal Joints in the propshafts (both propshafts), these can be loose (worn), or tight (almost seized) and you have to unbolt each joint to get a true assessment. From your comments, I assume you have changed these.

The auto box does suffer from a cracked flexplate, but this would have become apparent, I think, in the 180 degree move you had done.

Don't forget the obvious, of a tyre defect, or out of balance.
Wheel bearing is possible, but I think you have discounted those.
CV joint in the front drive shafts? Possible but unlikely.

Have you compared your car (now you have changed the propshafts) with another 38A?

If you do change the differential, front or rear, go for the 4 pin ones from Ashcrofts. There is no setting up, it's just pull the halfshafts / driveshafts, unbolt the old, bolt in the new, fill with oil, and that's it. Easy money.
There is more work if the old diff has left a lot of metal behind, in which case you need to make up a swab, of paper towel around a broom (brush) handle, and wipe out axle tubes, pushing and twisting from the wheel end towards the axle centre.
It's still easy money though.

HTH
 
#10 ·
My 99 4.0se has a vibration in the drive train and to me the vibration is intense and close together that I believe that it is coming form the drive or prop shaft (depending on you termination). It is not a real strong vibration but you can tell its there. To me it is like the air-compressor vibration but that is just a comparison. A mechanic told me first to take off the front drive shaft and drive it around and see if that has any affect. I gusts had the front end aligned and tires balanced and the balance made no change as I assumed would happen. ALSO in the other thread, MAKEING A 180 DEGREE TURN ON THE FLEX PLATE WITH OUT OPENING OR REMOVING THE TRANSMISSION :?: :?: LOST ME ON THAT, COULD YOU EXPLAIN TO ME ABOUT THIS ? Do the drive shafts get out of balance on the rovers? I have had this problem with other vehicles. Around here there are shops the can balance the drive shafts. I have yet to run this on a rack but when I do I think I will block up the axle housings on all four corners and see if I can tell then where the vibration is coming from, I hope. I bought it with 114,000 miles on it and now has about 138,000 miles. I also changed the viscous coupling and that made no differenct on the vibration.
 
#11 ·
Hi Chas,
Thanks for your comments first of all,helpful indeed.
That kind of vibe really made me hate the vehicle for about months now and looking for a solution.
I never tought and think that a GM guy will deliver any better service to LR but LR people around here are just chasing after you to change as much parts possible.
By shafts,excuse my English , i meant propeller shafts.By changing them i lost a big part of the vibration at the lower speeds,but still high speed shudder continues.Especially when i ease my leg from the throttle.When i hit the throttle a bit again just to take the gap vibe goes away,not completely but can say %80-90.
That makes me think bearings,have a set at the trunk to be changed but dealer really Insists not to change them ,probably cause i have them at the trunk,paid by me ,not to be selled by them.
I guess i'll change them next week when i have time.
I have three different sets of wheels,all OEM LAnd Rover,without any cracks,or ever hit anywhere,2 of them with Michelins,synchrone and XPC,and the other set with 255/60 /18 Good Year Hp Wranglers with a few thousand miles on them,but still no change.
 
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