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D2 - Transmission Gearboxes, diffs, drive shafts. |
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ZF 5HP24A - Rear axle ratios – just the two?
Hi everyone. My first post on the forum – please be gentle
I have an interest in the ZF 5HP24 transmission and I have a fair amount of experience of its use in Jaguar, BMW and Range Rover applications but none, unfortunately, of the 5HP24A variant used in the Audis. Clearly the 5HP24A is quite a bit different to the 5HP24, having the integrated front ‘axle’ and the Torsen differential unit in the transmission itself. From what I can gather there are three different front 'axle' bevel gear sets used : 3.0909 (34/11) 2.9091 (32/11) 2.7273 (30/11) as well as three alternative ratios for the front propshaft idler gear drive : 1.2069 (35/43/29) 1.1724 (34/43/29) 1.0000 (29/39/29) and five alternative rear gearset ratios to drive the rear propshaft : 0.9063 (29/32) 0.8529 (29/34) 0.7838 (29/37) 0.7742 (24/31) 0.7368 (28/38) All the potential combinations are actually reduced down to (just) five overall options, shown in the list below, which covers all 27 Audi variants of the transmission : My question is, am I right in thinking that there are just the two rear axle ratios available i.e. 3.7000 (37/10) and 4.111 (37/9) for Audis fitted with the 5HP24A? If that is the case then drive to the front axle from the Torsen unit will always lead the rear slightly by between 0.04% and 0.46% depending on the model. Not that this is a large amount as, at worst, this speed difference is only equivalent to having 1.5mm less tread on the front tyres than the rears if the gearing at the front & rear was absolutely identical. I just wondered if any other rear axle ratios were offered by Audi with this transmission? Phil Last edited by RRPhil; 13th December 2013 at 09:55 AM. |
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Hi Phil,
Nice to see you in the forum. I'm afraid I can't answer your question in any detail whatsoever but I'm fairly sure there are only 2, one in he A8 and the other in the S8. The S8 is certainly more rev happy than the A8. I know that is the case for the face lift models but not sure about the pre-face lift. Hopefully someone else and clarify in more detail.
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Currently driving - '99 Silver A8 D2 FL 4.2 QS Currently for work - '08 Raven Blue T5 174 |
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I really shouldn't type so quickly on my phone!
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Currently driving - '99 Silver A8 D2 FL 4.2 QS Currently for work - '08 Raven Blue T5 174 |
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S8 revs much higher both PF and FL. So probably the same/similar ratios though the controllers and programmes are different.
My PF and FL seemed to be very similar revs at "motorway" speeds. Or in the back lanes out in the East Midlands today.
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2003 D2 FL S8. Irish Green Pearl/Beige. Solar sunroof, auto-dim mirrors, electric rear seat functions, ski hatch retrofit; extended leather. Aftermarket DVB-T, reversing camera and full XCarlink (Bluetooth etc.). 2016 Volvo V40 T5 Cross Country (4WD) with ALL the toys including adaptive cruise etc. etc. Osmium Grey with Blonde/Charcoal leather interior. Polestar performance "optimisation". (A much rarer model than a D2 S8 by the way!) Oh, and a brand new engine at just under 30,000 miles on the factory one! Finally: gone, but not forgotten..... 1998 D2 PF S8. AgateGrey/Platinum. Every option (I think) except electric rear seats, tiptronic steering wheel, ski hatch, towbar & dimming door mirrors. e.g. Cruise control, NavPlus/TV, Bose, GSM, Xenons, Solar roof, Parking sensors, Alcantara/leather everywhere of course. (internal dimming mirror added later) 1998 (very early) Ford Focus 1.8 Zetec; ABS/TCS, Heated screen/mirrors, Aircon, Auto-dim mirror, Leather, Trip computer, Cruise control, OEM Ford SatNav with CD changer. And before that a lot of Rover 800s, a few oddities, a lovely Triumph Dolomite 1850HL with Overdrive and way back in my schooldays an Austin Seven aka Mini 850! |
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If the ratios where the same front and rear gears can chatter causing wear and noise, the tinny difference keeps the gears meshed
Dave
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2002 S8 silver with black half leather 2000 d2 S8 in Racing green pearl, RS4 manual gearbox, 2003 A4 avant TDi 1997 Volvo V40 2.0T 1992 Mazda eunos v spec 1976 Reliant Kitten 1965 Porsche 911 |
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