V8 - Is it worth proactively overhauling gearbox before it blows up ?

This site contains affiliate links for which LandyZone may be compensated if you make a purchase.
T

tonymccandless

New Member
Posts
140
Location
FK15 0NR, Dunblane, Scotland
May seem like a strange question but with recent buy L322 in garage for front diff I wonder if at some point it would be worth (or indeed is possible) going proactive on the gearbox and getting the TC etc looked at & replaced BEFORE the bloody thing goes bang ?

Has anybody done this ?

v8Saint : is this just me being paranoid after 2 dead RR's this week ? :scratching_chin:
 
Gearbox rebuild is no peace of mind, simply because the cost of RS2000CUSTOMs 'preventative maintenance' was the same as rebuilding the gearbox once failure has happened. Do a gearbox oil and filter change and get whoever does it to look at the 'old' oil. If there's a lot of bits or (worse still) glitter in it then a strip down and rebuild is worthwhile. Otherwise just keep the oil and filter changes as a regular partof the servicing...

The one BIGGEST thing that will prolong the life of your gearbox is to not to drive a TD6 like its a 4.4 V8 RR or to thrash it (or chip/remap it)!!

Enjoy your Rangie...and hope the dreaded BONG never sounds!!
 
They are better apparently BUT given the way my luck is going this week and the mileage on the L322 is 53k I wonder if the investment may just be worth it in the long run.

Dropped Mackie's a mail and see what they come back with on price.
 
2.0_hippo said:
Does the ZF box suffer the same TC failure as the GM box ??

I thought they where better ?
Click to expand...
The main issue with the ZF box is the Bearing inbetween B and C packs fails, this causes the B clutch to move axially on the shaft which wears the O ring between B and A clutches.....the O ring then fails and causes a drop in hydraulic pressure on the A Clutch creating slippage....the Torque Converter tries to limit box slippage to around 3% by modulating the Lock Up Clutch to prevent excess slip.....

If the A clutch (which is used in all gears bar 5th) is slipping the LUC is working overtime and startes to wear exponentially (like the GM Box) and deposits friction material into the oil....which creates more wear and in worse case trashes all the clutch pack friction plates meaning a total rebuild, in the best case just a replacement of the A clutch plates, Torque Convertor and oil/filter change.

Here is the offending Bearing....
14Needlerollersmissing.jpg


15Looseneedles.jpg


And the failed O Ring......
16O-ringfailed.jpg


(photos by RRPhil/Bemble)
http://greenoval.homeunix.org/rr/zf5/16O-ringfailed.jpg
 
Discotigger said:
Gearbox rebuild is no peace of mind, simply because the cost of RS2000CUSTOMs 'preventative maintenance' was the same as rebuilding the gearbox once failure has happened.
Click to expand...

Correct with a great big BUT !

My box has not been subjected to the aggressive wear caused by the swarf from a failed Torque Convertor (inevitable to fail) particularly within the valve solenoid block.

As for Tony's original question at 53k I would do an oil and filter then repeat a further fluid change in 1000 mile.

The ZF has a better reputation than the GM box fitted to my TD6
 
Last edited:
RS2000CUSTOM said:
Thats me forked then - lol

Done 120 mile trip tonight from home to Hereford and back and Sport mode was used on many occasions :D :D :D

As for my DPT chip box - it dont half work well - lol lol lol
Click to expand...

That's the issue, the TD6 does bloody shift like a 4.4 once chipped
I can see why they used it in the x5 and they shift too !!

I'm just changing the gearbox filter and oil very frequently to stop any metal swarf building up

So surely if there's no swarf in the box the gearbox can't trash itself ??
The TC will just stop working once its worn out no ??
:scratching_chin:
 
2.0_hippo said:
So surely if there's no swarf in the box the gearbox can't trash itself ??
The TC will just stop working no ??
:scratching_chin:
Click to expand...

In my humble opinion purely based on the crap filling the void between my ears ! :p

It is when the TC inevitably fails that the swarf is produced and then forced around the rest of the gearbox.

A regular oil and filter change should (fingers crossed) prolong the life of the TC - whereas we are all at the mercy of RR/BMW originally stating "sealed for life" and in the 2nd 3rd 4th or 5th hand market we all knocking on 100,000 miles on what could be original oil and worn clutch plates within the TC just waiting to explode
 
RS2000CUSTOM said:
In my humble opinion purely based on the crap filling the void between my ears ! :p

It is when the TC inevitably fails that the swarf is produced and then forced around the rest of the gearbox.

A regular oil and filter change should (fingers crossed) prolong the life of the TC - whereas we are all at the mercy of RR/BMW originally stating "sealed for life" and in the 2nd 3rd 4th or 5th hand market we all knocking on 100,000 miles on what could be original oil and worn clutch plates within the TC just waiting to explode
Click to expand...
The fail point on the GM box is the Valve Block - particularly with the pressure modulation solenoid to the Torque Converter Lock Up Clutch wears out the bore which reduces the pressure to the LUC which causes premature wear.

This wear dumps friction material into the oils which then acts like a cutting paste causing addtional wear....

Cleaning and filter change will only delay the inevitable.

The problem is the Valve Block which can be replaced with one from the company whos name I can never remember called Solex, Sonnex or Sonax or something like that!
 
Great info all and many thanks for it. I think approach will be to get the car fully services whilst diff is in for fixing (incl changing gearbox oil) and to see what Mackie quote anyway.

Some small relief to hear ZF is a little more sturdy....
 
I will admit, the ZF box is a lot stronger than the GM box, that's why they put a different box on the 4.4 V8's. The doozel RR's should never be driven like the petrols, which is what we all want to do!! Power without the fuel cost!!

I am 100% for preventative maintenance, which is why I have just spent a few pennies getting my steering rack replaced (plus other bits!), but that was because I had play in the steering and the handling was not what I would class as good.

However, when it comes to the gearbox...until it starts to feel 'iffy' (and any good driver knows what I mean by that! At least I hope so), then why try to fix something that's not broken?
 
RS2000CUSTOM said:
Thats me forked then - lol

Done 120 mile trip tonight from home to Hereford and back and Sport mode was used on many occasions :D :D :D

As for my DPT chip box - it dont half work well - lol lol lol
Click to expand...


OUCH!!

390Nm Engine...340Nm Gearbox ... + Performance Chip(??Nm) = Overstressing!!

One eventual outcome, heartache and empty wallet!!
 
Saint.V8 said:
The fail point on the GM box is the Valve Block

Torque Converter Lock Up Clutch wears out the bore which reduces the pressure to the LUC which causes premature wear.
Click to expand...

Is it a chicken and egg scenario though ?

Which fails first ?

The valve block or the TC

I plumbed for the TC and in my own GM box the valve block had only polished surfaces within the accumulators and valves etc

I did have 1 snapped accumulator spring but in now way would I have described the internal bores as being worn

BUT

the TC's clutch plate wear was clearly evident as a black deposit in the sump pan.

So in my case the TC was gonna be first to fail.

What I did not want was the potential to have a damaged valve bloke hence the new TC and gearbox strip

VMTP are Sonnax agents and this was also a deciding factor for having them do my rebuild as IF the valve block was knackered I was going to have a sonnax upgrade fitted
 
Last edited:
Discotigger said:
OUCH!!

390Nm Engine...340Nm Gearbox ... + Performance Chip(??Nm) = Overstressing!!

One eventual outcome, heartache and empty wallet!!
Click to expand...

i cant understand why LR put an overrated engine in with an underrated gearbox ??

it goes against all science and concepts !!!

why not keep the same ZF gearbox in the TD6 too ???!?! :scratching_chin:
 
RS2000CUSTOM said:
Is it a chicken and egg scenario though ?

Which fails first ?

The valve block or the TC

I plumbed for the TC and in my own GM box the valve block had only polished surfaces within the accumulators and valves etc

I did have 1 snapped accumulator spring but in now way would I have described the internal bores as being worn

BUT

the TC's clutch plate wear was clearly evident as a black deposit in the sump pan.

So in my case the TC was gonna be first to fail.

What I did not want was the potential to have a damaged valve bloke hence the new TC and gearbox strip

VMTP are Sonnax agents and this was also a deciding factor for having them do my rebuild as IF the valve block was knackered I was going to have a sonnax upgrade fitted
Click to expand...
The fail point is the Valve Block IMHO....

Maybe I rushed my post above and doesn't read right....

What happens is the original block was made from a very soft aluminium and as the valves move, they wear the bores they sit in, the TC modulation valve moves around more than most to modulate the hydraulic pressure to the LUC to prevent GB slippage to around 3%...this constant movement wears the bore out quickly and this reduces the hydraulic pressure to the LUC which starts to slip, so the modulation valve starts moving more, which wears the bore out quicker....which again causes the LUC to slip prematurly wearing out the friction material on the LUC plates....

This dumps crap into the oil which turns it into a fine cutting paste effect and this then starts to wear out the GB clutch friction plates, which means the LUC has to work harder to prevent slippage...causing more friction plate wear....and the cycle continues....

A replacement TC will have better friction material, but with the wear in the valve block, whilst it will last longer than the original, may still be prone to exponential wear eventully....but should be good for 100k at least.
 
You must log in or register to reply here.

Similar threads

H
L322 gearbox
Replies
5
Views
1K
myfirstl322
M
H
L322 gearbox
Replies
1
Views
802
Mark Piercy
Mark Piercy
L
R380 MANUAL GEARBOX - WATER IN OIL - IS THERE A BREATHER??
Replies
9
Views
2K
lrjohn
L
C
Other Disco 1 V8 Auto gearbox
Replies
19
Views
3K
Cappo
C
Chazb5046
Disco 2 Cost after purchase?
Replies
16
Views
2K
ronsealdeath
ronsealdeath
Back
Top