treetotreef Posted July 28, 2008 Report Share Posted July 28, 2008 Hi All, Just an update on my gearbox woe's continuing from the thread below: http://www.tyresmoke.net/forum/audi-a8-s8/108757-differences-between-a8-4-2qs-s8-2.html#post1329892 I decided to start a new thread with a clearer title to help others if they are using the search filter for the common transmission problems with these cars. As per the previous thread, I had some pump cavitating noises from my DYM gearbox. I reset the level, it looked like it was overfilled by the previous mechanic, and my problems went away…for a while. But problems never really go away do they! On the motorway 2 weeks ago the gear display kinda inverted itself, i.e. instead of the numbers/letters being red and background being black, it changed to a red background and black letters. I now understand this to be ‘Limp home mode’ (please correct me if I’m wrong on that one). It selected 4th itself and locked me out of the controls, D,4,3,2,+,- didn’t do anything. I took the next exit off the motorway but by the sliproad it was slipping badly. By the time I got recovered, there was a large pool of ATF under the car. Game over, ball burst! I got a quote from VM Transmissions near Heathrow of £1500+vat for a full rebuild. Found them on Remanufactured transmissions and genuine ZF parts from the ZF Car Parts Centres. This was not an option, so on to plan B! Dave at A8 parts was very helpful, but only had an A8 4.2 QS box in stock. I toyed with the idea of changing the rear diff to match the final drive of the 4.2QS type DTD (the A8 4.2 QS DTD has lower final drives and a theoretical higher V-Max…3.73:1 for S8 vs 2.727:1 for A8), but as I wanted to get back on the road as quickly as possible, I didn’t want to take the risk that the S8 gearbox ECU’s shift points may not suit the DTD. As I luckily have the use of a 2 post ramp on the weekends, I decided to do the work myself. I sourced another DYM trans from a scrappy, the car had been rear ended, and without x-ray vision, that’s my only guarantee that the box is ok. I got the scrapyard torque converter rebuilt for ~£160 by the above mentioned ZF agent to reduce the risk. Apperatly there was a problem with the lock-up plates in that one so they replaced them as well. It was cheaper to get the filter,gasket, o-rings etc. from Audi than from the ZF agent, so including a rear diff output flange seal, it came to ~£55 with a little trade discount (always ask, they can only say no!) Oil was from Lubricants.org | The UK`s Oilstore | Esso ATF LT 71141 | Exxonmobil...~£138 delivered For everyone’s peace of mind, I found this document on line, a fantastic parts catalogue for the ZF 5HP24A trans. It qotes Esso ATF LT 71141 as the preferred oil and also gives a filling guide/procedure similar to audipages.com http://www.zf.com/na/content/media/import/zf_na/startseite/sso/passenger_car___light_truck/car_driveline/product_catalog/5HP24A.pdf It also gives very clear exploded views of the different components of the trans. Unfortunately I found the audipages guide on gearbox removal after I got mine out! It recommends removing the subframe, and now I do too! We did get the gearbox out with the subframe in but it’s very difficult, there’s not much space in there, we ended up pulling the trans back then trying to rotate it 90 degrees with the front diff pointing up and dropping it that way. Having done this once, I wouldn’t do it again, its very dangerous as rotating the trans on the gearbox hoist is both difficult and dodgy. We had a strap as safety going from the 2 front legs of the car hoist, and boy was I glad I put it there! The only benefit to that way is that you don’t have to support the engine and while you are sourcing/rebuilding your trans, you can remove the car from the ramp and push it outside out of the way. Expect to find lots of rusted nuts and bolts, hopefully not to many rounded torx heads as I did. I tool I would highly recommend,( and this may be obvious to some on this forum) is a selection of punches. Use the various sizes to fit into the torx heads, give them all a good whack before loosening. This breaks the rust/corrosion and they screw out no problem. This trick also works well for sump/fill plugs for the front/centre and rear diff. Clearly the guy working on the car before me didn’t know about this as I found so many rounded, I has to resort to a chisel to get them turning. I gave the scrappy transmission a much needed service with the parts mentioned above. The oil didn’t smell great and when I dropped the sump, and I found the usual furry creatures living there. My guess is that there is only so much metal filings these magnets can attract as they were all full but there was more in the oil. [ATTACH]33552[/ATTACH] Excuse the quality of the pictures, only my mobile at hand. See attached what the sump did,(above) and should,(below) look like! [ATTACH]33553[/ATTACH] I didn’t have any at hand, but I wouldn’t mind adding a few more magnets in there, it certainly wouldn’t do any harm. One thing I really don’t understand is why the drain plug isn’t the lowest point of the sump. Another magnet or two would be nice in there, or better still, another drain plug! Job for another day tho… [ATTACH]33554[/ATTACH] As per audipages.com , I mounted the rebuilt torque converter to the gearbox first, and the flywheel last. See the pics below of how to get your old torque converter off. You have to remove the engine subframe, to remove the starter, to get at the 3 bolts located 120 degrees apart behind the flywheel. [ATTACH]33555[/ATTACH] [ATTACH]33556[/ATTACH] In this pic you can see where I tied a strap from coil spring to coil spring around the engine and used a ratchet strap to tension it. Engine was also propped from the front. Again, a good whack of a punch, in the side this time, helps to loosen the torque converter bolts. It helps if you roughly line up the first hole on the flywheel with the corresponding location on the torque converter. Be sure to push it back all the way into the transmission, a little twisting is required and it should click back all the way. It all bolts together easily enough when the sub-frame is out of the way, it may be worth guessing or trying to work out the correct height of the engine/box as it sits in the car, this will help when tightening up the exhaust bolts. Lambda sensors are a real bi**h to reach and clip in. So, when I got it all back together, I put as much new oil in the gearbox as it would take when switched off. I started it up and immediately the pump starts screeching. In hindsight I would have filled the torque converter with as much as it would take, then fit it. To cure this I figured that it should be no different to priming an engine after a rebuild, so I unplugged the fuel pump fuse, crank again for a while. It takes more oil again. I put the fuel pump fuse back in again, switch on the ignition, listen for the fuel pump working against the pressure regulator and crank again…but it won’t start! I’m pretty sure I’ve got enough cranking power/speed. I confirmed that I have spark on 1 cylinder I took all the plugs out, (which were wet, confirming I have fuel) and dried them out I turned the engine over with the plugs out to blow out any fuel in the bores I’ve even checked the airbox for blockages! (unlikely but I’m clutching at straws here!) It hesitates, like its trying to start, but won’t fire. Has anyone any other ideas on this issue? The frustrating thing is, that it started Saturday night, but won’t on Sunday! If it wouldn’t start after fitting the gearbox, you’d think, ok I’ve nipped a wire or left something unplugged, but this has me stumped! Link to comment Share on other sites More sharing options...
IT_S8 Posted July 30, 2008 Report Share Posted July 30, 2008 Hi All, Just an update on my gearbox woe's continuing from the thread below: http://www.tyresmoke.net/forum/audi-a8-s8/108757-differences-between-a8-4-2qs-s8-2.html#post1329892 I decided to start a new thread with a clearer title to help others if they are using the search filter for the common transmission problems with these cars. As per the previous thread, I had some pump cavitating noises from my DYM gearbox. I reset the level, it looked like it was overfilled by the previous mechanic, and my problems went away…for a while. But problems never really go away do they! On the motorway 2 weeks ago the gear display kinda inverted itself, i.e. instead of the numbers/letters being red and background being black, it changed to a red background and black letters. I now understand this to be ‘Limp home mode’ (please correct me if I’m wrong on that one). It selected 4th itself and locked me out of the controls, D,4,3,2,+,- didn’t do anything. I took the next exit off the motorway but by the sliproad it was slipping badly. By the time I got recovered, there was a large pool of ATF under the car. Game over, ball burst! I got a quote from VM Transmissions near Heathrow of £1500+vat for a full rebuild. Found them on Remanufactured transmissions and genuine ZF parts from the ZF Car Parts Centres. This was not an option, so on to plan B! Dave at A8 parts was very helpful, but only had an A8 4.2 QS box in stock. I toyed with the idea of changing the rear diff to match the final drive of the 4.2QS type DTD (the A8 4.2 QS DTD has lower final drives and a theoretical higher V-Max…3.73:1 for S8 vs 2.727:1 for A8), but as I wanted to get back on the road as quickly as possible, I didn’t want to take the risk that the S8 gearbox ECU’s shift points may not suit the DTD. As I luckily have the use of a 2 post ramp on the weekends, I decided to do the work myself. I sourced another DYM trans from a scrappy, the car had been rear ended, and without x-ray vision, that’s my only guarantee that the box is ok. I got the scrapyard torque converter rebuilt for ~£160 by the above mentioned ZF agent to reduce the risk. Apperatly there was a problem with the lock-up plates in that one so they replaced them as well. It was cheaper to get the filter,gasket, o-rings etc. from Audi than from the ZF agent, so including a rear diff output flange seal, it came to ~£55 with a little trade discount (always ask, they can only say no!) Oil was from Lubricants.org | The UK`s Oilstore | Esso ATF LT 71141 | Exxonmobil...~£138 delivered For everyone’s peace of mind, I found this document on line, a fantastic parts catalogue for the ZF 5HP24A trans. It qotes Esso ATF LT 71141 as the preferred oil and also gives a filling guide/procedure similar to audipages.com http://www.zf.com/na/content/media/import/zf_na/startseite/sso/passenger_car___light_truck/car_driveline/product_catalog/5HP24A.pdf It also gives very clear exploded views of the different components of the trans. Unfortunately I found the audipages guide on gearbox removal after I got mine out! It recommends removing the subframe, and now I do too! We did get the gearbox out with the subframe in but it’s very difficult, there’s not much space in there, we ended up pulling the trans back then trying to rotate it 90 degrees with the front diff pointing up and dropping it that way. Having done this once, I wouldn’t do it again, its very dangerous as rotating the trans on the gearbox hoist is both difficult and dodgy. We had a strap as safety going from the 2 front legs of the car hoist, and boy was I glad I put it there! The only benefit to that way is that you don’t have to support the engine and while you are sourcing/rebuilding your trans, you can remove the car from the ramp and push it outside out of the way. Expect to find lots of rusted nuts and bolts, hopefully not to many rounded torx heads as I did. I tool I would highly recommend,( and this may be obvious to some on this forum) is a selection of punches. Use the various sizes to fit into the torx heads, give them all a good whack before loosening. This breaks the rust/corrosion and they screw out no problem. This trick also works well for sump/fill plugs for the front/centre and rear diff. Clearly the guy working on the car before me didn’t know about this as I found so many rounded, I has to resort to a chisel to get them turning. I gave the scrappy transmission a much needed service with the parts mentioned above. The oil didn’t smell great and when I dropped the sump, and I found the usual furry creatures living there. My guess is that there is only so much metal filings these magnets can attract as they were all full but there was more in the oil. [ATTACH]33552[/ATTACH] Excuse the quality of the pictures, only my mobile at hand. See attached what the sump did,(above) and should,(below) look like! [ATTACH]33553[/ATTACH] I didn’t have any at hand, but I wouldn’t mind adding a few more magnets in there, it certainly wouldn’t do any harm. One thing I really don’t understand is why the drain plug isn’t the lowest point of the sump. Another magnet or two would be nice in there, or better still, another drain plug! Job for another day tho… [ATTACH]33554[/ATTACH] As per audipages.com , I mounted the rebuilt torque converter to the gearbox first, and the flywheel last. See the pics below of how to get your old torque converter off. You have to remove the engine subframe, to remove the starter, to get at the 3 bolts located 120 degrees apart behind the flywheel. [ATTACH]33555[/ATTACH] [ATTACH]33556[/ATTACH] In this pic you can see where I tied a strap from coil spring to coil spring around the engine and used a ratchet strap to tension it. Engine was also propped from the front. Again, a good whack of a punch, in the side this time, helps to loosen the torque converter bolts. It helps if you roughly line up the first hole on the flywheel with the corresponding location on the torque converter. Be sure to push it back all the way into the transmission, a little twisting is required and it should click back all the way. It all bolts together easily enough when the sub-frame is out of the way, it may be worth guessing or trying to work out the correct height of the engine/box as it sits in the car, this will help when tightening up the exhaust bolts. Lambda sensors are a real bi**h to reach and clip in. So, when I got it all back together, I put as much new oil in the gearbox as it would take when switched off. I started it up and immediately the pump starts screeching. In hindsight I would have filled the torque converter with as much as it would take, then fit it. To cure this I figured that it should be no different to priming an engine after a rebuild, so I unplugged the fuel pump fuse, crank again for a while. It takes more oil again. I put the fuel pump fuse back in again, switch on the ignition, listen for the fuel pump working against the pressure regulator and crank again…but it won’t start! I’m pretty sure I’ve got enough cranking power/speed. I confirmed that I have spark on 1 cylinder I took all the plugs out, (which were wet, confirming I have fuel) and dried them out I turned the engine over with the plugs out to blow out any fuel in the bores I’ve even checked the airbox for blockages! (unlikely but I’m clutching at straws here!) It hesitates, like its trying to start, but won’t fire. Has anyone any other ideas on this issue? The frustrating thing is, that it started Saturday night, but won’t on Sunday! If it wouldn’t start after fitting the gearbox, you’d think, ok I’ve nipped a wire or left something unplugged, but this has me stumped! Not ignoring you down here, but I think we're all a little stumped. Excellent write up, and top marks for effort, but can't think why its failing to start. The V8's will start even if the Transmission ECU is completely absent, so missing or nicked wiring doesnt sound to be a viable culprit to me..... I spent half a day chasing a starting problem to find that i was low on fuel, the fuel guages can lie a little sometimes... Link to comment Share on other sites More sharing options...
treetotreef Posted July 30, 2008 Author Report Share Posted July 30, 2008 I did think about that, but i have taken it into the red before (until the central computer warning light comes on) so i ruled that out at the weekend. But its worth a try, I've picked up 8 new NGK spark plugs and 5 litres of fuel at lunchtime so i'll try this evening and see what happens. My ebay VAG-COM serial lead also arrived today, but i'm having trouble connecting it. It installs ok, attaches itself to COM3, but when you run the recommended test, it says "Port status ok , interface not found" I've used the usual: Right click on My computer->manage->system tools->device manager->Ports(COM & LPT) and it confirms that its on COM 3. i've tried changing to other ports but no good either. Anyone out there have any similar problems? Link to comment Share on other sites More sharing options...
LostKiwi Posted July 30, 2008 Report Share Posted July 30, 2008 You need to check the version of VagCom software you are using. If its a non-genuine cable then you can't use the latest versions as they use a dongle in the lead. Not sure which version works though (mine is all genuine). Link to comment Share on other sites More sharing options...
treetotreef Posted July 30, 2008 Author Report Share Posted July 30, 2008 i'm trying to use 409.1 which is not the latest one. It came on a CD with the lead. i've aslo tried rolling back to 311.2 but no use... I di have an old redundant laptop at home, i might try that this evening... Link to comment Share on other sites More sharing options...
EddyH Posted July 30, 2008 Report Share Posted July 30, 2008 Is there an LED on the lead and if yes is it illuminating when you plug it into the car with the ignition on? Link to comment Share on other sites More sharing options...
treetotreef Posted July 31, 2008 Author Report Share Posted July 31, 2008 Got VAG-COM to work! I stumbled across a random internet page that sais some computer/car model combinations can only be tested when plugged into the car, so did that westerday evening and hey presto! So i got a whole load of fault codes to look through now 18010 Power supply Terminal 30: Voltage too low 16684 16689 16691 16688 17978 16692 16944 16705 16496 It explaines the first fault code but the rest came up with a 'shareware version' note. I'll check the wikipedia page for these codes today.I'll anso try and roll forward to 409.1 again to see if it will work. To answer your question EddyH, its hard to see the led on this particular lead as it faces forward and in daylight it appears too difficult to see if it's illuminated or not. i didn't try it at noght, but got a connection so i presume it was lit up. Link to comment Share on other sites More sharing options...
EddyH Posted July 31, 2008 Report Share Posted July 31, 2008 I was asking to check that as it sounded like it wasn't connected to the car properly, you answered that though as you didn't have it connected at all and that's why it wasn't working! You can only test the cable with it connected to a car with the ignition on. BTW did you clear the codes as some could have been in there for a long time? You need to clear them, try starting the car again and then rescan the fault codes. Link to comment Share on other sites More sharing options...
harpersimon Posted July 31, 2008 Report Share Posted July 31, 2008 VAGCOM is at version 8+ now, so 4 etc are fairly old. I even had trouble with the USB genuine lead (Of Kiwi's) until I got a decent modern version of V'com on the lappy. Link to comment Share on other sites More sharing options...
treetotreef Posted August 1, 2008 Author Report Share Posted August 1, 2008 Ok, I've cleared the codes, tried it again and no start. It didn't produce any new fault codes either which is annoying. I've also tried 8 new plugs but no start. its just doing the same thing, you could only call it a cough, not even a splutter. As the plugs were out i decided to do a quick compression test just as a sanity check. left bank is really good...175-200psi but the right bank is borderline 140-110psi. thats not worrying, and certanly not causing the no starting, but its someting to think about for the future. it could be leaking past the rings or across the head gasket. I also tried cleaning up the earth strap going from the chassis leg to the engine(close to the starter), it didn't look that bad but cleaned it anyway and no good. Next up is the crank sensor. As i understand it, a crank sensor creates a voltage, so disconnecting it and putting a multimeter across the pins should give me a reading(~2v). does anyone here know the correct voltage created at ~500rpm(starter speed)? or can this be looked at using VAG-COM? Link to comment Share on other sites More sharing options...
LostKiwi Posted August 1, 2008 Report Share Posted August 1, 2008 Fuel pumps are a common problem on these cars - have you checked the fuel pressure (wet plugs may or may not prove a thing as if the fuel pressure is low it may not give sufficient to start the engine). Also check all the engine connectors are fully pressed in and none have come apart. Best undo all the connectors, eyeball for bent pins, then reconnect them. Finally check anywhere where a wire runs close to the engine or body to make sure there is no cracked insulation. You should be able to see the cranking speed and ignition timing on VagCom (at least you can on the later versions) when you crank the engine over. I'm pretty sure it uses the crank position sensor to calculate engine RPM. Link to comment Share on other sites More sharing options...
treetotreef Posted August 1, 2008 Author Report Share Posted August 1, 2008 I'll try that this evening, but the thing smells of fuel after trying to crank it, so I think its getting some. I unplugged the cam sensor to check the voltage across the pins on it. while a mate was cranking it, she nearly started! Anyone out there got a wiring diagram for an '98 S8? Link to comment Share on other sites More sharing options...
treetotreef Posted August 4, 2008 Author Report Share Posted August 4, 2008 Latest update... It was my cam sensor that was causing the problem. I took it out, cleaned it and put it back in and it started. the nut wasn't particularly tight, so i'm not sure if it was that or the cleaning that helped. I noticed that it looks like the triggers (square's on the flywheel) were rubbing on the snesor, but when i measured the dept, it looks like there is a good 3-5mm od space of an airgap between them, indicating that there is no way they could have touched it! Has anyone else noticed this? see pic below from audipages guide... Anyway, delighted that it starts again, i put all my tools away, washed my hands etc, and then went to check it 1 more time...no start!!! AAAAGH! this thing is really testing my patience. its different this time, more like a loose connection. no sound of any relays clicking or the starter solenoid engaging, just the battery light goes out when you attempt to crank and nothing happens. I've done the earth near the starter, next step is the rest of them... Oh, and when i started it, after all the days of cranking, the gearbox is still whining...maybe i bought a dud gearbox from the scrappy...it just gets better and better. If thats the case, i'm seriously considering a manual conversion! or opening up one of these gearboxes to see what goes wrong... Link to comment Share on other sites More sharing options...
treetotreef Posted August 17, 2008 Author Report Share Posted August 17, 2008 It's Alive! finally got round to having a look at the s8 this weekend...got it up on a 2 post ramp again to see why it wouldn't start. i began by looking at the junction box under the drivers side chassis leg, took the 2 positive wires off to clean them up. they were quite bad, but no signs of arcing/burn on any of the terminals, so i wasn't too hopeful that this was my problem. while doing this i noticed a plug with some insulation tape on it. Thinking this didn't look like 'genuine audi tape' i peeled it off and it looked like someone had botched it up cause the plastic plug housing was broken. terminals looked pretty corroded so just cut it off, replaced it with some bullet connectors and hey presto...it starts! I also found out what the noise was coming from the transmission.I posted recently that the crank sensor was not that tight after i installed the scrappy box,(but was pretty sure i had tightened it) ald that it liiked like it was rubbing the triggers on the flywheel. after cleaning it the first time and tightning it up again i gave another look at it while it was up on the ramps. it looked like it was touching again! more plastic material pushed down towards the bottom of the sensor and more wearing on both the plastic and magnetic trigger. looking closer at my old gearbox and where the crank sensor goes in, I now see the problem. the caphead bolt sheared off when taking the old sensor off that gearbox. there's a ~5mm spacer where the sensor sits and that stayed on with the broken stud. In the workshop we put some washers in there just to start it and away she went. No more transmission noise. filled the gearbox and went for a spin. It seems a little clunky, but for the moment I’ll put that down to the software relearning the new gearbox(I hope!) But that wasn’t the end of the drama’s…the car is only on 6 cylinders now! I feel like in the few months of owning this car I’ve come across every common problem these ones get. VAG – COM says cyl 7 missfire, so I pulled the 4 coilpacks out from the left bank to measure the resistance across the pins, but that didn’t produce anything concrete. When I’ve measured other coilpacks I’ve got readings of 12-15 Mega Ohm’s, but these only gave a reading of 0.6 ohm’s on all 4. next I plugged them all back in and then unplug 1 at a time while the engine is running. Unplugging Cyl 5 and 7 made no difference to the idling sound or speed of the engine, so I swapped them with cyl 6 and 8 to see if it was the coil pacls or something else. The problem didn’t follow the coil packs, so now I’m thinking it’s the coil amplifier. I’ve read the test procedure on audiworld, so that will be the next thing to try. Can anyone on here tell me where to find these coil amplifiers on a ’98 S8? Link to comment Share on other sites More sharing options...
treetotreef Posted August 28, 2008 Author Report Share Posted August 28, 2008 latest update on my bottomless money pit is that my coil amplifiers tested ok. I found that you could make the missfire go away by switching the car over to lpg, which would point to a petrol injector as the cause. I've read numerous posts regarding MAF's and their effect on automatic gearboxes, so decided to change that. £189 quid later (from eurocarparts) and the miss fire is gone. MPG seems to be better too, but its early days yet to tell for sure but with both the old and new MAF's i'm still getting a gearbox fault code 17125 - Torque Converter Clutch Circuit Performance or Stuck Off. I've put a reconditioned Torque converter in when i did the gearbox, so i hope it isn't that. wiki ross tech has a number of causes and solutions 17125/P0741/001857 - Ross-Tech Wiki the symptoms are hesitation when i try to pull away, and as i slow down it can't decide which gear to be in, sometimes thumping it into 1st. I read somewhere that the solenoid valve block has a fine mesh screen protecting each of them...has anyone else on here got as far as opening their valve block up? Link to comment Share on other sites More sharing options...
Figure11 Posted August 28, 2008 Report Share Posted August 28, 2008 tttf Try a read though this FAQ. You may find it useful. The Auto section is 3/4 the way down. Mike Link to comment Share on other sites More sharing options...
las247 Posted August 28, 2008 Report Share Posted August 28, 2008 TTTF Having read through this with interest I am amazed at your level of competence with the car. Most of what you have written has completely lost me so am following loosely. One thing I would say is to stick with it, I have had trouble with mine recently from a gearbox rebuild, MAF sensor, brakes, wheels etc. However once done there is nothing like driving the thing jsut think forward to the leasure yu will gain from it. All the best. Link to comment Share on other sites More sharing options...
treetotreef Posted August 29, 2008 Author Report Share Posted August 29, 2008 Thanks LAS 247 I know exactly what your saying. I feel I've had every common problem that these cars have in the few short months since i purchased it, but when that V8 starts up, all is forgiven! She's being a real bitch tho! But everything is fixable, so on we go! Feel free to ask me anything that you don't understand, (but there's no guarantee that i understand myself!). there's no such thing as a stupid question! Thanks also Figure 11 some good info on there. It should come in useful. If anyone's interested, i've found where i read about the "fine-mesh inlet screen" http://64.233.183.104/search?q=cache:2XXz3LmSbO4J:tech.bentleypublishers.com/thread.jspa%3FmessageID%3D355180%26tstart%3D0+5hp24A+problems&hl=en&ct=clnk&cd=6&gl=uk Link to comment Share on other sites More sharing options...
Oli18 Posted September 1, 2008 Report Share Posted September 1, 2008 Hi treetotreef I am in awe of how far you've taken this so far! A real inspiration. Don't feel that the lack of replies has been due to it being a low-interest topic...it's seriously good to know that some people will stop at nothing and have such a great hands-on approach. Keep us posted on how you get on as it's invaluable info for us all! -Oli Link to comment Share on other sites More sharing options...
Ska Posted September 1, 2008 Report Share Posted September 1, 2008 2nd that, weldone fella! Link to comment Share on other sites More sharing options...
Figure11 Posted September 2, 2008 Report Share Posted September 2, 2008 Aaaaaaand third that. I shall check the screens when I do my ATF change next year. If the chance of some photos comes up of the solenoid removal.............. +++ Mike Link to comment Share on other sites More sharing options...
Ska Posted September 6, 2008 Report Share Posted September 6, 2008 This worth a read: AudiWorld Forums: Whoa! The THUMP! revealed Link to comment Share on other sites More sharing options...
IT_S8 Posted September 6, 2008 Report Share Posted September 6, 2008 Dave at A8 parts was very helpful, but only had an A8 4.2 QS box in stock. I toyed with the idea of changing the rear diff to match the final drive of the 4.2QS type DTD (the A8 4.2 QS DTD has lower final drives and a theoretical higher V-Max…3.73:1 for S8 vs 2.727:1 for A8), but as I wanted to get back on the road as quickly as possible, I didn’t want to take the risk that the S8 gearbox ECU’s shift points may not suit the DTD. Well, it might be interesting to note that since this we've had a customer who complained of a vibration on their car, which turned out to be the fact that the S8 gearbox had failed and someone has replaced it with one from a 4.2 A8. They failed to change the rear diff, to the different final drive ratios caused the center diff to work overtime and vibrate. Changed out the S8 diff for an A8 one and voila..... ... an S8 with sensible* fuel consumption, and still 340BHP..... We've not verified this hands on, but seems viable to me and he certainly seemed to understand his stuff. BTW, I agree this has been an interesting write up...... ! * sensible is a relative term :-) Link to comment Share on other sites More sharing options...
Oli18 Posted September 7, 2008 Report Share Posted September 7, 2008 This worth a read:AudiWorld Forums: Whoa! The THUMP! revealed Great find on the article SKA! Had a read and although it goes over my head a little, it would be a good one to save in case my box ever starts with the symptoms and i need to take it to a transmission specialist. Have attached the file for people's reference in case it gets removed from the site... -Oli Link to comment Share on other sites More sharing options...
treetotreef Posted September 16, 2008 Author Report Share Posted September 16, 2008 (edited) Its been a while since I’ve checked on here, but thanks to all that replied. That article is a very interesting read indeed and certainly along the lines of what I’m on about. About 2 weeks ago I set about looking for these screens. I carried a proper camera with me, so got some decent pics… I dropped the oil, its worth noting that it’s only done ~180 miles with the fresh oil in and its already pretty cloudy again, just goes to show, its worth changing the oil twice. Dropped the sump pan…see pic 1&2. Note the sludge already attached to the magnets and colour of oil And your left with the view in pic 3. From the ZF parts catalogue(pic 4), 700 is a shift solenoid (x3 marked blue), 701 is a shift control solenoid (x4 marked green), and 702 is a main pressure control regulator (x1 also marked green but sits further into the valve block) Taking these off is surprisingly easy; just unclip the wiring loom…and undo the 8 torx heads which fix the retaining bar.(pic 5) The retaining bar drops easily down(pic 6) And pop each solenoid out with a screwdriver…(pic 7) On mine, the filter on the main pressure control regulator (702 marked green buts sits further into the valve block) shown in pic 7 on the left was very badly clogged up with metal filings and sludge(below)..(pic 8) I had trouble removing the screen from the solenoid, so I left it in but carefully removed the metal with a small magnetic screwdriver and then used a cotton ear bud to clean the remaining sludge out. The remaining 4 green solenoids were spotless and there is no filter screen to be seen on the blue shift solenoids Refitting is pretty much the reverse of the above, but keep the order the same (pic 10), i.e don’t mix the solenoids up!. Standing behind the solenoids, remember the solenoid on the left has a different part number to the other 4 green ones, As of yet, I don’t know the differences between them, but I don’t want to find out the hard way! I haven’t got round to filling the box fully yet with fresh oil, as I ran out of time (holidays, work etc.) but I’ll report back on the result as soon as I do… Edited September 16, 2008 by treetotreef Edited cause pics didn't come out when placed between txt Link to comment Share on other sites More sharing options...
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