J.R.

Increasing the bore size of the master cylinder will reduce the braking force (for a given pedal force) and drastically reduce pedal "feel" and the ability to modulate the retardation. If you fit larger discs using the correct caliper mounts you increase the braking force (for a given pedal force) and heat dissipation, the master cylinder bore size should not be increased unless the brakes have far too much response and bite, it is never good practice to change more than one parameter without judging the effects and contemplating at length any further modifications. How do you "tell the car" that you have fitted a larger bore master cylinder?

It means dont do that again!

Thanks, saved me looking again, if I had a memory I would not have needed to.

I'm fairly sure my Yeti does not have seperate caliper carriers and the whole steering knuckle needs to be replaced, I will go and have another look though. Standard clutch. 6 speed gearbox factory build.

Mine also but it depends on where the temperature sender is in the coolant circuit, is your car a DSG by any chance? They have a second DSG thermostat which often fail.

I'm sure what you said earlier will come to pass, that you will adopt another one! It sounds like you moved the AC compressor without disconnecting the flexible pipe couplings, wise man 👍

Is the aircon functioning Pete?

Yes well done! You understood my probably poor description and managed to do the required tests and give the results. Your differential is behaving exactly as it should, I can confide,tly say that there will have been no loss of drive to the front wheels, the clutch is looking like the suspect if drive was lost but I would like to hear exactly how your SIL describes the event and what led up to it. The only slight doubt is: That is subjective, if I were there I could say if it were abnormal or not, if you move either the input shaft or the driveshaft flanges back and forth you will see, feel and maybe hear backlash, I would not describe it as rattly though. Could he have experienced a "handful of neutrals"?

Thanks for the info. I have been in sub zero temperatures with the heater on full driving on very light throttle as always and usually have to go up a steep hill or give it some beans to help the gaage over the 75/80° mark to jump up to the 90°. On one of those occasions only after the temperature gauge had got to its fiddle factor 90° I think I was driving very slowly on a back road looking for somewhere and the load on the engine did not create enough excess heat to keep up with the heater, I noticed the temperature gauge needle fall very quickly (but nonetheless damped) to 60 or 70°c, I knew why it happened, there could have also been some hysteresis on the thermostat. It was the first time in driving VAG vehicles since 1998 that the gauge needle has behaved in a relatively true manner! On older cars you could always see the swings in temperature and if you had something with an inherent cooling weakness like my Triumph Stag you would drive always with one eye fixed on the needle, so well did I know the micro-deviations that the day I was accelerating from the last roundabout before my home 3/4 of a mile away I saw the gauge go up a tiny bit quicker than normal, I stopped the engine immediately and saw that the water pump was leaking, I had bought it with blown head gaskets, warped heads and seized head studs, stopping when I did saved it from a second occurrence.

Sounds like I have forgotten the exact construction, I'm sure that on mine I disconnected both shafts from inner flanges in order to remove the entire transmission including the bevel drive in one piece.

I'm jealous of the satisfaction that you are going to get from this!

I admire your faith. Ask yourself this question, have you ever seen the temperature gauge indicate a steady temperature between 75° and 90° or between 90° and 110°? I bet it has always risen or fallen fairly quickly through these ranges, quickly as in damped but not instantaneously, faster than the engine could actually change through that temperature range.

It's the latter that makes my mind boggle! I thought that Superbs were even more economical than Octavias due to their aerodynamics. I did 13 full on laps of Croix en Ternois race circuit in my MK1 Octavia 110 TDi, its a very windy technical circuit, we were 4 up as I was instructing. I reset the trip meter before going out and the overall fuel consumption was 19mpg, the lowest I think you could ever get out of one of them, so 31mpg seems very high indeed.

Dont you mean the drivers (RH) side, you need to refit the quill shaft which passes through the bevel drive gearbox you do not need the bevel drive gearbox, you simply need to have both driveshaft flanges connected to the diff, the RH one, the quill passes through the centre of the hollow transfer box input shaft, it can be hanging in free air for the test. Or simply do what you have already done in turning the LH diff flange while looking at the splines on the other side which if a gear is engaged and the clutch input shaft restrained should rotate in the opposite direction to the one you are turning.

What you have described is absolutely correct, the bevel drive gear is driven directly from the crownwheel, you need to refit the quill shaft and test the planet gears in the way I described, turning one alone without any significant resistance is normal. Don't take it to a transmission specialist, you have been taken for enough money already, if you give them a perfectly functioning transmission saying that its faulty but you dont know where they could profit from the situation, doing something like that in my country earns the moniker "pigeon" - a willing victim, someone whose naiveté or ignorance is to be exploited. To repeat: Completely normal You do not know that (lack of) front drive is a problem, that is what a mechanic who knows little or nothing about the system has said and what you have wrongly deduced from testing the differential incorrectly, refit the quill drive and do the testing as I described. The only thing you know from your sons first hand report is that all drive was lost, if there was power to the rear the vehicle would not have lost all drive, I think looking at the clutch might take you straight to the resolution, that and asking your SIL to describe exactly the circumstances when drive was lost.

If I had have fitted them this winter (we didn't actually have one!) then I would have refitted the normal tyres about 2 weeks ago, by that time the thousands of cranes has passed overhead returning from their migration route and the bees and wasps were buzzing around looking for holes to make nests in, that happens when the temperature remains above 10°c.

I havn't put them on yet!!!!!!!!!!!!! And that goes for the last 2 maybe 3 years. Not one of my wiser purchases since moving to the sunnier South, in Northern France they may not have been essential every year but when you needed them boy did you need them! Mine were rock hard and may have worked in snow but were lethal the rest of the time so when I saw a set of virtually new steel wheels and winter tyres on Facebook down here getting cheaper and cheaper I bought them for next to nothing. Now I know why they could not sell them! If I were to still visit the ski slopes they would be needed, if ever we do get a bog snow fall I will use them, otherwise I will wait till my recent new tyres wear out which will be 60k+ miles based on the old ones, I bought the exact same.

I only skipped through it but I agree the presentation of that video is excellent for non German speakers, the red highlighting was very well done.

Maybe my senile memory is not serving me correctly but I believe that the front differential is an integral part of the transmission assembly and you cannot remove the gearbox leaving it on place, you can however remove the transmission leaving the bevel drive transfer gearbox in place, I lifted both out as one unit, 68kg. The more you post the more questions there seem to be, perhaps the Caddy transmission is different to the other VAG vehicles which I am certain be they FWD or 4x4 all have the differential within the transmission casing.

@Prezafab A total lack of drive is not a Haldex problem. @Alasdair1 I appreciate your position with the 2nd and 3rd hand info. My speculation is that your son in law broke the clutch during the testing, not overheated, burned or worn out but a failure of the pressure plate (I exclude the drive plate because you would have seen that) that would result in a total loss of drive albeit you would normally notice the lack of pedal resistance. I was trying to work out if the mechanic had jacked up the rear wheels whether with a tiny bit of torque transfer the front diff cage could rotate and spin the rear propshaft, the Haldex I dont think will engage if the front wheels don"t turn so it would only be the propshaft with little resistance, I asked myself maybe that is what the mechanic saw? In my minds visualisation I decided that the differential crownwheel and quill drive to the bevel gearbox and propshaft could not turn if the LH and RH driveshaft planet gears were stationary, conceptualising is not my strong point so I jacked up the rear of my car to try it out. DONT TRY THIS AT HOME CHILDREN 😀 I did it very carefully first in 6th gear (less chance of driving off the jack) and then very very carefully in 1st gear, the conclusion was definitive, if the rear wheels are off the ground the car will indeed drive forward in gear.

He should pay the mechanic if he instructed him to do the work he has done.

Thanks, still a mystery as to why there would have been no drive but that is the question to ponder as the drive to rear appears to be a red herring, if that were the case your son would not have experienced "no drive" Maybe change the thread title or delete it and start a relevant one? Could you ask your son under what conditions the lack of drive occurred, was he pulling away hard from a standstill on a loose surface to confirm that the 4x4 was functioning?

I realise I have misread the text, not crownwheel bolt but cover bolt, I would negotiate to get the vehicle back without paying and then inspect the crownwheel, if they don't play ball tell them you will bring an expert with you to their premises to make a formal insection and report.

According to the party line from the garage the recall and the damage are unconnected and to be fair, if a crownwheel bolt really did come loose causing the breakdown it is indeed nothing to do with the service campaign. "You welded my daughters car and now she is pregnant!" - yes I really did hear that one once! @UndertheRadar asks the very pertinent question.

Worth it in what terms? Substantial difference to what? Nobody can advise you on a hypothetical situation of being stopped by the Police and whether you consider any hypothetical fine to be "worth it" for the value you get from the modification.