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Transmission Rebuild, 6.9

Started by TJ 450, 03 January 2009, 07:56 AM

TJ 450

#30
You're probably right, P.B.

I removed the intermediate shaft this afternoon. Again, there is subtle differences. If you look at the pics, it's pretty self explanatory. The dimensions of the shafts are the same overall, for both transmissions. The 450 version has one flattened ridge where the friction discs locate.

Will it work? I think it will, but how much of a compromise is it? :-\

Edit: The 6.9 version is machined from a solid piece, the 450 version is welded together.

Comparison - side view, L=450 R=6.9

Comparison, Base, L=450 R=6.9...

6.9...

450...

6.9... Thicker base.

450... Lighter construction, flattened ridge...


...Tim
1976 450SEL 6.9 1432
1969 300SEL 6.3 1394
2003 ML500

koan

Have you determined where the extra 10mm is in the 6.9 transmission as compared to standard 450?

koan
Boogity, Boogity, Boogity, Amen!

TJ 450

Not as yet, but I'm working on it. I'll compare all the parts and report the findings. I'm expecting to find that it is the rear/output shaft that is longer.

Tim
1976 450SEL 6.9 1432
1969 300SEL 6.3 1394
2003 ML500

koan

Just found http://w126.pp.ru/akp722.pdf on mercedes@mercedesmailinglist.com.

koan
Boogity, Boogity, Boogity, Amen!

TJ 450

Thanks, Koan. That's a good document, even though it is for later transmissions in the series, the basic concept is the same and it is very useable information.

I have the bellhousing from the 450 trans on the bench at the moment, which is being sacrificed to attempt removal of the stator shaft. I'm surprised, as it doesn't want to move at all and there is no info in the manuals on removal, either. Hmmm.

Tim
1976 450SEL 6.9 1432
1969 300SEL 6.3 1394
2003 ML500

Big_Richard

Quote from: TJ 450 on 04 February 2009, 09:09 AM
Thanks, Koan. That's a good document, even though it is for later transmissions in the series, the basic concept is the same and it is very useable information.

I have the bellhousing from the 450 trans on the bench at the moment, which is being sacrificed to attempt removal of the stator shaft. I'm surprised, as it doesn't want to move at all and there is no info in the manuals on removal, either. Hmmm.

Tim


Your more than welcome to try my press if you dont utterly distroy it before i return to perth ;)

PS. dont buy compaq laptops, their shit, once warm the keyboard gets a mind of its own.

TJ 450

Thanks for the offer, P.B.
I'd probably rather wait until you return though, I might end up getting impaled with a stator shaft or something. ;)

Tim
1976 450SEL 6.9 1432
1969 300SEL 6.3 1394
2003 ML500

Big_Richard

Quote from: TJ 450 on 07 February 2009, 11:35 AM
Thanks for the offer, P.B.
I'd probably rather wait until you return though, I might end up getting impaled with a stator shaft or something. ;)

Tim

Thats what i meant...

IE, not distroy the bellhousing before i return ;)

TJ 450

I began investigating the "practice" valve body (out of the 450 trans) this afternoon. It has been dissasembled and soaked in petrol. I was surprised at the level of dirt in there.
I just need to devise some sort of clamping method and I'll be able to re-assemble. I'll go through the process several times until I get the hang of it completely. The same thing will be done with the entire transmission.

Here's something to look at (click for 800x600 versions)...





Tim
1976 450SEL 6.9 1432
1969 300SEL 6.3 1394
2003 ML500

s class

Cool TJ, thanks for the update.  What exactly about the valve body needs clamping?


[color=blue]'76 6.9 Euro[/color], [color=red]'78 6.9 AMG[/color], '80 280SE, [color=brown]'74 350SE[/color], [color=black]'82 500SEL euro full hydro, '83 500SEL euro full hydro [/color], '81 500SL

Big_Richard

on the topic of valve body's, don't buy the autohaus valve body rebuild kit as it doesent fit properly. Who ever makes the gasket has their cnc machine setup incorrectly and its about 10% too large with the holes only lining up correctly on one side, at the other side they don't even line up. One could bodge it to work by centering it so the error is spread across  the valve body progressively worse going to the sides but why bother - The genuine one fits perfectly.




TJ 450

The clamping is required when installing the intermediate plates, to allow proper seating of the valves and to ensure everything goes together properly. Because of the springs, everything needs to be contained. My W123 280/250 Haynes manual suggests using nuts with a slot ground out of them such that they resemble a "C"... I'll investigate this evening.

Tim
1976 450SEL 6.9 1432
1969 300SEL 6.3 1394
2003 ML500

TJ 450

I thought it was time for an update.

I have a seal kit and spigot shaft on its way. I have been told by several "experts", that the two shafts out of my transmission cannot be repaired due to the risk of failure. The metal is surface hardened and to sleeve it would require machining off a substantial amount of material.
So, I either need to find a used transmission or install the shafts out of the 450 unit or spend 3k, if the shafts are still available.

At the moment, I'm in the process of tearing down a W126 unit off a recently aquired 380SE. A perforated trans cooler in the radiator allowed coolant into the trans with the usual results. It's all good practice. ::)

Tim
1976 450SEL 6.9 1432
1969 300SEL 6.3 1394
2003 ML500

WGB

For the shafts - Does it have to be a 6.9 transmission or will a 450 one do?

Bill

TJ 450

The shafts out of a 450 transmission will work fine, the 6.9 ones are beefed up though. I do have a set out of a 450 transmission here, so I could just assemble it with them.

Tim
1976 450SEL 6.9 1432
1969 300SEL 6.3 1394
2003 ML500