4.8 auto gearbox rebuild in the UK…
 

Hi All, I think I need an automatic gearbox specialist in the UK….. my gearbox is slipping when on 3/4 throttle and driving uphill, and a trans fail safe prog message popped up yesterday. It cleared on restart, but I had the following error codes when I scanned with DIS:

EGS Signal Line disturbed

EGS 4F8A ratio monitoring gearshift 4-5 plausibility

Can anyone recommend somewhere in the UK I can contact? My car has 126,000 miles on, I changed the filter and fluid about 10,000 miles ago, and while I will check for low fluid, I am not confident that another fluid and filter change is all that’s required… I’ve not yet heard a positive story about reconditioned gearboxes - so if anyone has any direct experience/can recommend somewhere, that’d be great.

Many thanks…

RRPhil is a member here and is quite well versed with these transmissions, and their repair. I believe he’s in the UK so you may want to PM him.

RRPhil is clearly a sensible man - as he’s turned off PMs! Tried to message him, but looks like he’s disabled that function - Imagine he’d be inundated!

If he does see this then I’d be grateful for a recommendation…

It may be worth removing the Mechatronic unit and testing the E-clutch port with air pressure to see if the rear stator bush is worn. The E-clutch is used in 4th, 5th & 6th gears and the proportion of input torque it sees is 72.6% in 4th, 125.5% in 5th and 100% in 6th. It therefore tends to slip first in 5th gear, but eventually the transmission refuses to upshift beyond 3rd gear when the controller detects slip in all three upper gears. If this were the cause, the transmission would slip less when cold, as the fluid viscosity is higher and therefore the leakage past the bush will be less.

Removing the Mechatronic unit also gives the opportunity to check the condition of the bridge seal and the four jump tubes.

Phil

Many thanks for the reply Phil. I’m in two minds about taking a deep dive into this myself. I’m quite mechanically capable with head gaskets, vanos and timing chains, plus the usual requirements of swapping over suspension and rebuilding things, but I wouldn't be able to remove the gearbox on my driveway if it transpires it needs a clutch pack, bearing or bush (it only slips when warmed up - as just took it out on the hill outside my house and no issues and no new codes…).

I think I’m going to have to take it somewhere to be refurbished having read around this a lot and seen others experience with fluid and filter changes and even swapping mechatronic valves. All looks very doable in terms of removing the mechatronic assembly and valves, but I’d be working on a driveway outside - and I reckon it’s likely to be something deeper in the box in light of the age and mileage of the car?

(Or am I being defeatist?!).



Can you recommend a gearbox specialist in the UK? Much obliged!

Getting the transmission out of the vehicle & back in again is definitely the hard part. Stripping & repairing the transmission is the easy bit (assuming, of course, that you have somewhere to lay out the bits). If it is your rear stator bush that’s worn, it’s the very first thing to come out of the transmission. You could replace it without delving in any further.

https://xoutpost.com/907717-post1.html

Any competent mechanic with a car lift should be able to remove the transmission, as there’s no specialist knowledge of automatic transmissions required. Might it be easier to find someone to remove and replace your transmission and for you to fix it?

I’m afraid that I don’t know any automatic transmission specialists who I could recommend ‘down south’.

Phil

Many thanks for this Phil. REALLY want to do this myself as love this stuff (and fortunately have a few other cars to get around in). I’ve had a recommendation from my M3 specialist of a place in Aylesbury. I’ll have a chat with them and then a think. I did an oil service and cv boot in thermals a couple of weeks ago - and don’t fancy that again for a while! Thanks again for your help.

If it’s STA, then I know that they have a Hydra-Test machine to test out valve bodies/Mechatronic units and that this represents a substantial investment. I used this same equipment to test out my own rebuilt valve bodies:

https://youtu.be/bFgB_OW9_PA

On the face of it, therefore, they appear to be a ‘proper’ outfit and I’d be interested to hear how you get on with them.

Phil

Hi - yep. He recommended STA and said he sends everything there.

Am getting closer to tackling this myself actually…. Don’t suppose you could recommend the best place to source ZF seals and solenoids? I was going to use bmw for the filter kit and fluid.

For genuine ZF parts from an official dealer I would use either JPAT (https://www.jpat.co.uk/) or Sussex Autos (https://www.sussexautos.com/)

Phil