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Did Mercedes manufacture the complete 928 automatic transmissions?

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Did Mercedes manufacture the complete 928 automatic transmissions?

 
Old 01-15-2009, 09:09 PM
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TheMirror
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Default Did Mercedes manufacture the complete 928 automatic transmissions?

OK, so the question title seems dumb at first, as it is well known that the A22 and A28 automatics were essentially the same internal design as the Mercedes 722.3 and 722.4 automatics.

What I'm curious about is where the Mercedes bit of the manufacturing leaves off. Did they supply the internals to Porsche, who manufactured the cases, or did Mercedes make the transmissions complete with case and Porsche just bolted them in.....or did Getrag somehow get into the mix?

Thanks y'all,
-Mirror
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Old 01-15-2009, 10:04 PM
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Old 01-15-2009, 10:23 PM
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This should be good......from what I understand.....Mercedes made the internals and Porsche made the rear end-case....but I'm not 100% sure on this either..... Steve Catteno will know for sure....he's the transmission expert!
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Old 01-16-2009, 02:11 AM
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I don't have a factual answer, but if you employ logic, you have to come to the conclusion that these transmissions must have been built at whatever Mercedes plant transmissions were made.

Why do I think so?

1. I have no idea where in Zuffenhausen they would have assembled the transmissions

2. The company has no in-house know-how in automatic transmission manufacturing. Would it be worth acquiring that for a few hundred transmissions per year?

3. If Mercedes has the facilities to assemble transmissions, they could do it more efficiently

So, let's see, if anyone knows any facts about this. I'll keep my eyes peeled for more info.
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Old 01-16-2009, 04:12 AM
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All parts which have MB part number were obviously same as in Mercedes gearboxes including actual gearbox case. This means practically everything between torque converter housing and differential are mercedes parts. Only part numbers starting with 922 (A22 3sp), 960 (A28 4sp) and obviously 928 are Porsche specific. There aren't many in area between converter and diff and those that are are mainly external selector parts. It would make sense that actual gearbox were made in same production line as Mercedes boxes and they were pulled off it for Porsche external parts at end of the line. Perhaps only once they were totally finished and some parts need to be removed even.

It would make sense that at least differentials were put in at same place where manual gearbox differentials were done, wherever that was, Porsche, Getrag or elsewhere. Same measurements need to be done in both types of gearboxes and it would be stupid to do such a specialized job in many different places.

Both of those would make sense but at the time Porsche did many things hard way.
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Old 01-16-2009, 04:52 AM
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One more thought: IF Porsche had any capability to build gear boxes THEN why did they need Aisin, and Getrag or ZF for the more recent models and not ELSE make those in-house?
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Old 01-16-2009, 06:52 AM
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My car's gear box has Porsche designation of A2816 3L 02446 stamped on the intermediate case.

In the Porsche Manual for Automatic Transmission A28 states on page 3 "The digitis stamped on the right side of the transmission case above the ATF sump are for production control only".

In actual fact these numerals are the Mercedes Benz series number and the transmission number.

For example, the 722 400 02 147104 has the following meaning:
a. 722 designates Automatic Transmission
b. The digit 4 designated the Model of Transmission. My car has a 722.3 series type transmission and the 3 designates that it is a 4 speed/6 bolt pan/Large Case
The numeral 4 above would designate that it is a 4 speed/6 bolt pan/Small Case.
c. The follow "00" designates the type of automobile or Version Number and is used to determine what modulator and the adjusted pressure required
d. The last six digits is the MB serial number

From the above I would suggest that the auto transmission was manufactured by MB, as a standard MB box with the ends designed to fit to the Torque Tube and the Transaxle.

This can be verified if you view PET and you can see the actual Porsche Part Numbers prefaced by 928 and the transition into the 960, 722 and 126 etc.

Not sure of the part numbers prefaced by 960, however, the 722 numbers and the 126 numbers are MB numbers, as far as I can determine.

Tails 1990 928S4 Auto
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Old 01-16-2009, 07:04 AM
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I always thought Merc made the casings but Porsche made the internals? Having said that you would think that if P commissioned M to help them come up with a slushbox, they would have had to use some of the M auto bits too, apart from the casing.
You would think the gearsets would at least have been Porsche derived?
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Old 01-16-2009, 07:16 AM
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Originally Posted by Tails View Post
In the Porsche Manual for Automatic Transmission A28 states on page 3 "The digitis stamped on the right side of the transmission case above the ATF sump are for production control only".
That is Porsches way of saying those number will not tell for what 928 gearbox was made for and only correct number is Porsches own style of numbering like A28/16... In reality MB numbers can be used to say to which 928 gearbox will fit.

Not sure of the part numbers prefaced by 960
960 is Porsche specific part for 4sp automatic same way as 922 is Porsche specific part for 3sp automatic. These are only parts which were specifically designed for mounting automatic gearbox into 928.

928, 911 etc part numbers are more generic model specific parts which were used in 5sp 928 and other Porsche models also.

123, 126 and 722 are all Mercedes parts which were used in some period MB models. They can be found from any MB parts supplier using same part number. AFAIK none of them are Porsche specific and this means 928 use exact same stuff as S-class MB for example.

900 and 999 are generic parts which are not designed specifically by or for Porsche. They are for example bearings which can be found from bearing manufacturer catalogs etc.
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Old 01-16-2009, 10:04 AM
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Originally Posted by TheMirror View Post
OK, so the question title seems dumb at first, as it is well known that the A22 and A28 automatics were essentially the same internal design as the Mercedes 722.3 and 722.4 automatics.

What I'm curious about is where the Mercedes bit of the manufacturing leaves off. Did they supply the internals to Porsche, who manufactured the cases, or did Mercedes make the transmissions complete with case and Porsche just bolted them in.....or did Getrag somehow get into the mix?

Thanks y'all,
-Mirror
I can't answer with any authority but,I just removed the auto trans from my wifes 85S and the donor 85S w/lsd and they both have a Mercedes emblem cast into the top of the trans case.
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Old 01-16-2009, 12:26 PM
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Awesome info guys, thanks a bunch! Geez you people are a goldmine of information.

All in all, sounds like its safe to say that the automatics (casings included) were indeed wholly manufactured by Mercedes Benz.....aside from perhaps some 928 specific mounting parts.

Cheers,
-Mirror
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Old 01-16-2009, 12:47 PM
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According to the shop where I got some spare parts for the transmission in my S4, it was made by ZF.

Edit
The shop could get spare parts for my transmission, but they were a lot cheaper at the local Mercedes workshop so I bought them there.

/Peter

Last edited by Peter Bull; 01-17-2009 at 07:21 AM.
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Old 01-16-2009, 12:47 PM
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Jim bailey - 928 International
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The front torque convertor cover allows the Mercedes transmission to be moved back from the engine to the rear and attach to the torque tube . The differential housing with the Porsche ring and pinion bolts to the back end of the specially modified automatic transmission case in place of the usual output shaft used on the Merc. Basically the same thing as was done on the 924 , 944 put the trans in the rear and hook it together with a LONG driveshaft torque tube just as GM had done in the early 1960s Pontiac Tempest ..... The 924 used a front wheel drive transaxle (Audi) simply moved to the rear. Pretty much answers the question about why there is no transmission fluid dip stick on the auto transmission to check fluid level on a 928 ......the transmission was supposed to be mounted to the engine !
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Old 01-16-2009, 12:59 PM
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OK just so I can be a complete pain in the ***, would Mercedes-Benz be the correct company designation to use for the automatic transmission manufacturer, or would Daimler-Benz be more correct? Looking through Ludvigsen's volumes on Porsche has him using Daimler-Benz.

On second thought, nevermind. Daimler-Benz may technically be more correct, but I have to stop this silliness somewhere. I'm gonna go list Mercedes-Benz in my specs database.
Thanks y'all.

-Mirror
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Old 01-16-2009, 01:24 PM
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Mercedes is a brand name of Daimler AG ...... much as Pontiac is a BRAND name for GM .....Jaguar for Tata ....
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