I finished the MYP gearbox conversion and DMF replacement yesterday evening.
Has anyone counted how many of us have done this mod now?
I managed to save a little time by not taking neither driveshaft out of the hubs, instead disconnecting the (pressed steel wishbone) balljoints from the wishbones by releasing the 3 screws. There was just enough room to fit the old flange shaft to the driver's side once the gearbox was mated to the engine again, but I had to turn the steering to full lock and take care of what was happening to the other driveshaft at the same time as I didn't release the steering tie rods or drop links either. I decided to keep the old clutch slave cylinder as the hydraulic pipe junction was at a different angle and I didn't fancy bending the pipe and maybe kinking it, so I didn't break the hydraulic circuit but somehow it had a load of air in and needed pressure bleeding with an old Gunson kit.
After adjusting the gear cables everything could be selected. With the car still on the axle stands and idling, I selected each forward gear and reverse without any adverse effects. Some air was punched! The ASR warning lamp was flashing though, clearly doesn't like having the back wheels stationary and the fronts at 35mph at 1000rpm in 6th.
The throw seems considerably shorter, not really notchy but somehow not quite so positive as before. It will take a little getting used to and the change of gearbox oil might see it ease up after a few miles. The new clutch feels (as it should) like a brand new car and the vibration from cold in neutral with the clutch engaged has mercifully vanished. I did a side-by side comparison of the old and new DMFs and the old one had wear that amounted to about 1mm up and down movement at the perimeter if you tried to pull up on one side of the clutch cover while pushing down diagonally opposite. The new one has zero movement, and this is for 2 Luk DMFs.
One tip: Elsawin says to put a M8x35mm screw into the front-most cable support bracket screw hole and use it to hold the clutch release arm back, and compress the slave cylinder before fitting the gearbox. I guess this is to guard against anything coming out of place inside before it is mated up. Obviously I read this and took off the cable support bracket from the newly-fabricated adaptors before fitting the new gearbox.
Thanks to Sarge for the link to his excellent post giving torque figures. The 2x countersunk head 6mm Allen key bolts that attach the old driveshaft flanges into the new gearbox need torquing to 25 Nm after compressing the springs a little. If I did the job again I would probably use a large G clamp for the compressing force but as it was I just used hand pressure to get the first couple of threads engaged but thinking about it, the spring reaction might have affected the torque a little.
It has taken me an embarrassingly long time to do this, probably more than 30 hours over the course of 2 weekends and 2 evenings but I do like to faff about quite a lot, look for tools I last saw 5 years ago, too many tea breaks, etc.
The gearbox mounting console bolts (multi-spline x3 and hex-head x2) as well as the centre pendulum bolt are all stretch bolts so should not be re-used. None were in stock at Audi, only the pendulum was available in 2 days and the other 2 types were on back order from Germany. Since these all have to come out for the relatively common task of changing the clutch I assume that nobody in the UK uses the new Audi bolts, or else re-uses the old ones. Given the choice of waiting 2 weeks or re-use the old ones with Loctite you can guess which way I went. I just re-torqued with the torque-wrench, leaving off the angle so as not to re-stretch and risk breakage. I also noticed that the wishbone bolts are stretch bolts, those have received the same treatment after cleaning the threads with a wire brush. I'm not 100% confident about this but my mates seem to think it's OK. Someone mentioned BMW or Mercedes give a max. permitted length for a stretch bolt for re-use but it seems not Audi.
I've been on a couple of runs, one to 70mph (2000 rpm) which was nice.
About swapping the flange-shafts: It seems the only difference between the GRJ and MYP flange shafts is the fact that the threaded holes for the 6 driveshaft boltas are M10 on the GRJ gearbox flanges and M8 on the MYP gearbox flanges. Is this correct?
Anyone want an old GRJ gearbox (you will need to swap your flanges!)
What did it cost me (all prices inc. VAT and delivery, rounded up to nearest £)
LUK DMF with clutch cover, driven plate and screws (ready-assembled to bolt on) eBay £435
MYP gearbox from Passat with 52 miles £340
LUK release bearing, arm and spring eBay £32
Front oil seal / clutch bearing sleeve eBay £15
Comma fully synthetic MVMTF Plus 75W gear oil Halfords £22
TOTAL £844
Obviously if I had not “needed” a new DMF then it would have been less than half the price. I think I was quite lucky to get the gearbox for that price, especially considering it came nicely shrink-wrapped and tied securely onto a custom made pallet.
Problem areas / still to do.
Notwithstanding the stretch-bolt availability debacle, the starter isn’t making a happy noise. I’m almost certain I remember torquing up both bolts properly. I am wondering if it is just the sharp burrs on the new flywheel ring gear teeth need to be worn off by the starter pinion, but you don’t get this noise from a brand new car… once I re-check the gear oil level on the flat later (I filled it with the car on the axle stands) I’m going to run it up the ramps and check the starter out before re-fitting the undertray.
I’m not certain that gear selection is quite as it should be. When I got the car the gear selection was fairly heavy and it has lightened up with regular use. I feel I need to go on a long run and get the gearbox fully hot before I’m happy that it’s OK.
I’ll be telling my insurance company as this is a non-standard mod.
Need to sort the gearstick emblem – I bought a cheap one but have misplaced it.
