Help...Overhauling 3 Spd Transmissions

Duckworth · Duckworth's Garage

....After a year of the car 'shaking' slightly and 'slipping' under load, I realize I have to do something with my '80 A/Trans. Has anyone here here ever overhauled their own auto trans ?

Folks generally advise you to stay away from such a project or point you towards Trans shops (Atlas etc.) but it should be remotely possible to try yourself. A GM video is around for a GM model rebuild anyway.

ZF trans in it - that has Mercedes, Porsche and Audi parts inside. One expert thinks Hydraulic actuators have worn out and /or brake band areas worn also.

...Automatics just have --- way too many parts in them for their their own good... That's what spawned the whole industry of various franchise shops. Most of the time their fix is to swap in a rebuilt unit.

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'82 Targa - sold
'80 928

m21sniper · 12-17-2006, 05:15 PM

Do yourself a favor, just buy a used 4 speed out of a part-out car.

The 4 speed will be the same as adding about sixty horsepower!

Brad w · 12-20-2006, 08:57 AM

Quote:

Originally posted by m21sniper
Do yourself a favor, just buy a used 4 speed out of a part-out car.

The 4 speed will be the same as adding about sixty horsepower!

Sniper, How will this seem like adding 60 HP? I also have a 3 speed that is in need of a rebuild and I did consider the 4 speed but haven't done anything yet. The 4 speeds start in 2nd correct? so I am not sure which one is better or stonger. Porsche however did make a change for a reason.

m21sniper · 12-20-2006, 09:28 AM

The 4 speeds have an extra and much lower first gear. Gearing is a torque multiplier. The lower the gear, the greater the torque multiplication, and the more gears, the lower the RPM drop between changes. Putting a 4 speed in your Shark will definitely increase performance.

SOME 4 speeds start in second, but will start in first with a 75% or greater throttle setting.

If i was you, i would definitely add the four speed.

The 4 speed tranny's are good for 600hp supposedly.

loose caboose · 12-20-2006, 09:51 AM

Guess I am stuck with my AT 84, but then I did the clutch shifting in the old days.

At least this AT doesn't slippppppp!

Nice AT!

JMO!

loose caboose · 12-20-2006, 12:59 PM

Quote:

Originally posted by Brad w
Sniper, How will this seem like adding 60 HP? I also have a 3 speed that is in need of a rebuild and I did consider the 4 speed but haven't done anything yet. The 4 speeds start in 2nd correct? so I am not sure which one is better or stonger. Porsche however did make a change for a reason.

It won't, just a benefit of gearbox torque multiplication. Automatic is not far behind..Transmissions do NOT increase or decrease the Horsepower of an engine. They just put it to the wheels

m21sniper · 12-20-2006, 01:31 PM

Which is the same as adding HP.

With a 4spd it will 'feel' like he added about 50-60horse.

Duckworth · Duckworth's Garage

M21Sniper - good tip about the 4 speed swap. The 3 speeed is the trans which was in the famous 6.9 saloon Mercedes car that had a huge torque motor. It was bolted up directly to the motor without the 928's transaxle design w/ diff attached. Someone told me it is considered the strongest of the automatic transmission designs.

Question - How hard is it to check out the flex plate at the trans end ? ? The 928 trans book only refers to a 'drive plate' and it's shown at the front of the trans just ahead of the converter (but hidden). How do you check it visually ?

Drop the whole trans assembly ?

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'80 928

m21sniper · 12-25-2006, 08:36 AM

For detailed tech advice like that i highly reccomend you call 928 specialists and ask for wally or dave.

Short of that, the nichols site is your best bet for step by step procedures:

http://www.nichols.nu/tips.htm

Richierich41 · 08-25-2012, 08:05 PM

Sorry to do this on my first post, resurrecting this old Topic: wondering what 4-SPd auto trans can be retrofitted to the 3-SPd 928? Any 928 4-SPd?

What about another tranny,like a 1992 968 tiptronic 4-SPd?

Thanks,
Rich

Richierich41 · 08-31-2012, 09:14 PM

Bump. Anyone? Anyone? Bueller?

AirtekHVAC · AirtekHVAC's Garage

This thread is a bit lengthy, but some very good info. And discussion on this topic

Brand New Transmissions Found! - Rennlist Discussion Forums

MPDano · MPDano's Garage

I too need to know what else is involved in the 3 to 4 speed switch. I need to do this in my Euro but hesitant to start since I am sure I will need other things in order to get it to work. All I have gotten in the past was that "I have done it." Or "I think I had to change the Bowden." Or "I think I was able to reuse the shift lever." Not really encouraging

Richierich41 · 09-02-2012, 07:53 AM

Thanks for the replies. I test drove an AT euro '81 yesterday. Found it very sluggish. I think I will post my newbie questions in a new thread. I have a few dumb Q's that I haven't been able to find answers for on this great forum.

MPDano · MPDano's Garage

Yup, my 81 Euro, a old lady in a walker with 4 broken caster wheels would blow my 3 speed away at the crosswalk. It only shows it's beastyness in the upper mph's. This is why I wasn't so sad when I drove my 3 speed tranny into the ground. I have a Euro 4 speed tranny but no real guidance on how to do it. Plus no space and time right now.