Richard Stewart

Richard Stewart

Member
Quick question to the gearbox guru`s on here.
I bought the car last August and it was coming up with the trans fail and it was due to 5th gear slipping.
Garage agreed to send it to auto box firm to have rebuilt gearbox.
Car came back but on driving was very lumpy on it`s gear change, which went after about 100mls but the trans Fail came back on.
So back to garage for repair.
Car came back and this time the box would judder on kickdown, as if it would not change down around 3500 revs but drove normally otherwise.
So took Range rover to Keith Gotts who read the code and this came up with a torque convertor monitor fault.
So back to garage who are meant to off replaced the once replaced Torque convertor and car comes back.
21 miles down the road, same symptons, box drives a ok until kickdown where it really judders and the car does not accelerate and then the trusty Trans Fail comes on again, carried on driving it to work for 60 miles as warning goes off and no more issues. Go to drive home from work and hey presto on with the Trans Fail and juddering change, any ideas before I call the garage today?
Thanks
 
Richard Stewart said:
Quick question to the gearbox guru`s on here.
I bought the car last August and it was coming up with the trans fail and it was due to 5th gear slipping.
Garage agreed to send it to auto box firm to have rebuilt gearbox.
Car came back but on driving was very lumpy on it`s gear change, which went after about 100mls but the trans Fail came back on.
So back to garage for repair.
Car came back and this time the box would judder on kickdown, as if it would not change down around 3500 revs but drove normally otherwise.
So took Range rover to Keith Gotts who read the code and this came up with a torque convertor monitor fault.
So back to garage who are meant to off replaced the once replaced Torque convertor and car comes back.
21 miles down the road, same symptons, box drives a ok until kickdown where it really judders and the car does not accelerate and then the trusty Trans Fail comes on again, carried on driving it to work for 60 miles as warning goes off and no more issues. Go to drive home from work and hey presto on with the Trans Fail and juddering change, any ideas before I call the garage today?
Thanks
Click to expand...
Get the garage to recover ,repair and road test it before you get it back. Have they offered a courtesy vehicle?
 
Or explain to the garage that you will be getting it repaired properly and you will send the bill to them.....
 
Have explained this to them and do have some experience with Mr Land Rover after racing them all over most continents in years gone by and working in a specialist garage but not having experience with this box.
So far gearbox garage no problems with sorting, but wondered if anyone can put a finger on the fault. Me, i believe it to be the valve chest in the box, possibly damaged by crud due to the crappy material they are made out of as a couple of the valves have been changed but most rebuild`s use the same one unless totally knocked out?
Would be good if someone with experience of this box could point the finger more!
 
just to reiterate, the garage that I bought the RR from is not the one doing the Gearbox repair, they are a big Autobox specialist. Or have the stickers!!
 
I have sent an email to the gearbox garage saying sort or else will be putting with trading standards as I have not had any calls back from them.
So just have to wait and see now but with the weight of social media a business can almost be burned alive if they choose no to respond to you?
 
From what I have read on here about these gearboxes is, if the gearbox is rebuilt get a sonex valve block as the original ones are poor quality and wear out and bleed of pressure to the clutch packs.
 
As Brian says above - and I think it is spelt Sonnax - sorry to be a pedant.....and even then I may have spelt it wrong.

The original valve blocks were made from a poor quality material and the valve spools were the block bores. Then pressure begins to leak past the valves, then the valves move more to modulate against this leak....accelerating the wear, this dumps a load of crap into the fluid on the wrong side of the filter...this turns the fluid into a cutting paste and wears the block even further and can begin to affect and wear the clutch packs and then box lunches itself!

The best rebuilders will specify a new Sonnax Valve block to be fitted.....as this is one of the best 'cures' of the GM5 gearbox issue.
 
Ok quick update, box rebuilt with new valve block etc and all put back.
Seemed to run perfectly but started to suffer a power loss so fired into keith gotts and fuel tank pump in tank suffering from low pressure so had that renewed.
Now drives much better but low and behold the dreaded Trans fail Program message came up again and has a few times over 200 miles.
Seems to be nothing wrong with car as drives fine, only thing that happens is the little tone to highlight the fault message sounds and then the message goes out again?
spoke to another rebuild specialist and they said stepper motor but high low ranges work fine with all the correct lights etc whilst operating the high low.
So come on Phil please put me out of my misery, what can it be.
Maybe try swapping over gearbox ECU?
 
Ratio change motor is a good call...the switch pack on the back of them goes brittle and cracks....no spare part, means a whole new motor.

As HC says, get codes read first.
 
codes read tourqe convertor monitor fault has been saying this since day one back in Nov 2017 and 3 rebuilt boxes later so i would say has to be something else?
 
Thanks Holidaychicken, already read that info.
Must admit the old bus drives remarkably well so fitted a tuning chip to the old bus and it is even quicker off the mark now, just see how the mpg goes?
 
certainly sounds like intermittent electrical fault if everything else is ok, there are more electronics inside the box as well.
It could just be a loose connection going to the transfer box motor
 
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