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Transmission Rebuild, 6.9

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

WGB

Years ago (more than I care to remember) I had a Mini Cooper gearbox main shaft built up using a technique call "Metalspray".

The worn area was built back up and then machined and case hardened - all in a little factory in Dunedin NZ.

Somebody here must be able to fix shafts in such a manner in this day and age and in this metropolis - especially with the mining industry being around the place.

Bill

TJ 450

Thanks Bill, that sounds like the way to go. I'll have to investigate further.

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

koan

Many many years ago Repco used to repair crank shafts by building them up and grinding to "new" size.

They don't do it now but there would have to be someone doing the same thing in WA given the amount of big machinery  about - as Bill points out.

koan
Boogity, Boogity, Boogity, Amen!

john erbe

Interesting. Do any of you guys have some parts schematics for the euro vs. US/AUS transmissions? Just had a euro trans put into my US domestic and learned from a pro that here is some bad info. out there in these 6.9 web sites, regarding the difference between the two trans. Apparently the the only difference is the valving and the torque converter. Obviously there is some different plumbing in that the euro doesn't have that circulating pump. But all this stuff about the number of planetary gears etc. is wrong.

koan

Quote from: john erbe on 25 March 2009, 02:40 PM
Just had a euro trans put into my US domestic and learned from a pro that here is some bad info. out there in these 6.9 web sites, regarding the difference between the two trans

I followed the thread on the International M-100 Group forum regarding the supposed differences between euro and US boxes with some incredulity. Nothing but incorrect information and from the site that holds itself to be the authority on M100 vehicles. A few years ago it was a good source but the not any more. I'd suggest that anyone seeking M100 information to treat what they read there with some caution.

Quote
Apparently the the only difference is the valving and the torque converter. Obviously there is some different plumbing in that the euro doesn't have that circulating pump. But all this stuff about the number of planetary gears etc. is wrong.

I would be very surprised if there are any differences in the valve body or torque converter either. The M-B transmissions and clutches manual mentions nothing
about euro and US versions.

There is a major difference between the 722 box used in 6.9s and the box used in 450s, the case is about 10mm longer to accommodate clutches with more plates. Not the only difference of course.

koan
Boogity, Boogity, Boogity, Amen!

zedster

I came across this browsing and thought I would post it just in case anyone is interested.

1980 Mercedes Benz 450sel 6.9 3 speed Auto Transmission

Bill
1979 450 SEL "Spinne Blaue"

Big_Richard

don't you just love it when so called experts crap on about stuff that they think their a full bottle on, only to be proven wrong, time and time again  :D Very amusing indeed. I look forward to looking and checking on my other computer with the world epc on it, which also includes north American delivery cars.

The rumors probably originate from the same charlatans who reassure you that you can't and mustn't even bother trying to reseal auto's at home, and must send them to their "workshops" post haste, along with $3000 to do what costs all of $500 using genuine parts. Always double check advice that comes with a sales pitch  8)

TJ 450

I was also following that thread. I agree that there is no mention of any internal differences between the two versions in the manual, nor did I discover any differences other than the external pump.

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

john erbe

Just had a euro trans put into my domestic with the idea being that front pump will someday go out and therefore I'm covered, one less headache to worry about. However,  soon felt like an idiot when I explained that I had heard that the euro was a better box and that there were distinct differences. Here I am, talking to a guy that was the shop manager for Mercedes in San Francisco for 17 years, and then went out on his own doing just transmissions. His response; ".. ah, these clubs, do you really think that Mercedes is going to build two different transmissions?" We then proceeded to his computer where he pulled up all the drawings showing that the valve body and the torque converter were the only parts that were different.

koan

#54
Quote from: john erbe on 26 March 2009, 09:18 AM
Just had a euro trans put into my domestic with the idea being that front pump will someday go out and therefore I'm covered, one less headache to worry about

Why do you want to lose the front pump?

My computer with EPC needs a Windows reinstall so I couldn't verify the torque converter/valve body bit but a quick look at an online EPC mentioned nothing.

EDIT: By front pump you don't mean  the front pump within the box but the aux transmission pump at the front of the engine?

The one the experts on the previously mentioned forum insist has a "special" bearing of unique dimensions and for that reason not available as part from M-B (don't quite follow that logic) or anywhere else. The same bearing I paid $12 for at a bearing shop.

koan
Boogity, Boogity, Boogity, Amen!

john erbe

Correct, the pump at the front of the engine. I want to eliminate when possible components which could lead to additional repairs down the road. After purchasing the car, that bearing in there had to be replaced and as I recall a stock bearing had to be machined down to fit.

koan

Quote from: john erbe on 26 March 2009, 02:26 PM
After purchasing the car, that bearing in there had to be replaced and as I recall a stock bearing had to be machined down to fit.

Most odd. Having read that forum I went off to the bearing supplier I use with bearing in hand and suggested it was a special size. It was measured and a stock replacement handed over.

koan
Boogity, Boogity, Boogity, Amen!

TJ 450

I received the new stator shaft and seal kit today.

Then, I noticed something odd... the part that presses into the bore of the bellhousing is a larger diameter on the new unit.





The part number is the same for all 3-Speed 722.xxx transmissions. What on Earth is going on here? The one that was pressed out of the spare 450 trans is the same as the one removed from the 6.9s bellhousing, a smaller diameter. It is an interference fit rather than being clipped in.

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

koan

Hard (for me) to tell which part is larger, is it the short, plain middle section?

How much larger is it?

koan
Boogity, Boogity, Boogity, Amen!

Big_Richard

#59
its the top section in the top photo, you can see its totally different, either wrong part put into the bag with that part number on it, or its not been finished properly, which is rare for MB to make mistakes like that.

You can always have it machined down to the same specifications as the correct shaft, the rest looks to be right.