mbz 71 109 6.3L?

[mbz72]

Hello List.

What do you think about this car?

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&category=6315&item=2471374120&sspagename=STRK%3AMEBBI%3AIT

Thanks.

cK

[JMela]

Discussed previously - Ebay deal must have fallen through.

super 6.3 on Ebay

[mbz72]

Thank You

cK

[Tomguy]

Is that the wrong speedo, or did the 6.3's have 4-spd autos?

[psfred]

Much to my surprise, I discovered that all the 6.3s have fluid coupling 4-speed autos! Only the 4.5L in the US had the three speed.

Peter

[Tomguy]

Peter: You just gave me another reason to buy a $1500 6.3

I assume the tranny would match up to the 4.5?

[psfred]

Sure, but what would you gain?

It's pretty much a tossup there -- the three speed has a torque converter and the 4-speed has a fluid coupling -- sort of like a torque converter with a locked up stator. Low slip conditions all the time.

My 220D has the fourspeed with fluid coupling, and takeoff is SLOW -- engine rpm in gear is limited to about 900 by the fluid coupling, and that's far enough down on the power curve to limit power terribly. Very sluggish until you get some speed up in 2nd.

The torque converter will permit the engine speed to rise much more (probably 1200 or 1400 rpm) with the tranny stationary, giving you the same effect as the lower first gear, and automatically "shifting up" to low slip (probably lower slip than the fluid coupling) as the speed comes up and the load drops off.

I have no idea why Benz used the torque converter 3-speed only on the 4.5L. However, by 1974, they had dropped the fluid coupling completely, so it may have been a matter of already having the engine tranny combination available and being somewhat reluctant to speed all that money on a very limited application (something like 6000 cars total production). The 6.3 was coupled to the K4A or K4C-050 tranny in 1963 in the 600 Grand, and I assume the drivetrain was dropped intact into the W108. The M116/M117 got considerably more money and attention, and a torque converter tranny was in the works anyway.

Peter

[gerryvz]

ALL 6.3s had four-speed automatic transmissions. The official model designation was K4A 050.

The Grand 600 engine/transmission was dropped into the 109 300SEL chassis, not the 108. The air suspension (self-leveling) is an important part of the 6.3.

The fluid coupling, while a rougher-shifting transmission than a torque-converter-based design, is also notably more efficient at transmitting power than torque converter designs -- less power is lost in the drivetrain. Also, the transmission as found in the 6.3, shifts MUCH smoother than fluid-coupling-based transmissions used with other engines (for example the M130 as used in the 280SE 108).

There were 6,526 300SEL 6.3s made. The transmission design was just a carryover from the 600 and Benz didn't do any additional engineering because of the nature of the project -- which was just an evening/weekend "special" hotrod put together by Erich Waxenberger and his team. Uhlenhaut drove the car and the DB board of directors decided to put it into production in limited numbers.

By the time that the M116/M117 engines were well into development, the decision had been made to move to an exclusively torque-converter-based design and away from fluid-coupling designs. A long-overdue decision if you ask me -- most other manufacturers had already moved to torque converters by the early-mid 1960s, before the 6.3 even came out in early-mid 1968.

Then again, Benz automatics have never been their strongpoint. From a refinement and durability standpoint, they really didn't get them tamed until the early-mid 1990s. Vs. GM (Turbo Hydramatic) and Chrysler (Torqueflite) which were quite well refined from the 1960s onward.

Cheers,
Gerry

[cth350]

Originally posted by Tomguy
I assume the tranny would match up to the 4.5?

Need a 4.5 tranny? -CTH

[Tomguy]

Not that I know of! Just want a 4-speed... but I'd prefer one with an OD anyway!

[Emmerich]

The 6.9 has a 3 speed as well.

[psfred]

Gerry:

I'd disagree on the Benz trannies -- even the old fourspeed ones with fluid couplings greatly outlast a Turbohydramatic. I've rebuilt several of the American types, and the Benz is much better built. The Chrysler Torqueflite comes close, but nothing made by GM is in the same ballpark.

Turbohydramatics usually melt all the plastic (!!!) support bushings by 90,000 miles, the clutch packs are gone about the same time, the stator support is worn from flopping around on the plastic bushing, etc. Not what I would call sturdy or reliable.

Rebuild every 90,000 miles (as on the Chevy van at work) is nothing compared to the 200,000 miles on all three of my Benzes with 722s (70's to 80's vintage). The tranny in the 220D works as well now as it did 32 years ago. Strange, hard shifts, but works fine.

The trannies in my and my brother's 85 Buicks croaked at about 120,000 miles, too, even with tranny fluid changes on my brothers.

Peter

[gerryvz]

Peter,

You're likely right on the transmissions -- I was talking a bit more on the refinement end rather than pure bulletproof durability though.

With the 6.3 the transmissions don't tend to last as long, because of the power. The major malady of them, however, is the dreaded "leakdown" whereby the seals dry out and allow fluid to pass through.

Then when you go to start up the car, the transmission slips until the fluid circulates and the seals get wet again. My 55,000 mile 6.3 takes about 7-10 days to hit full leakdown. Luckily you can avoid it by idling the car for a couple of minutes before heading off.

722s also tend to cost more than GM and other domestic transmissions to get overhauled, too.

Cheers,
Gerry

[Emmerich]

Gerry, what is the cure for the leakdown problem? New seals? Are they available? Is it a major overhaul to fix this?

thanks
Fred

[gerryvz]

New seals and a complete teardown to replace them. They are available but there are very few individuals or companies that are competent to do this work, and even then sometimes it doesn't "take".

Dan Smith runs about a 50% success rate with rebuilt 6.3 transmissions working out of the box. Very often they have to be redone (again).

You've probably heard Dan talk about leakdown. It could be a worse problem, but it's a pain in the butt nonetheless. ALl 6.3s have it, to varying degrees. Worst case is that it takes one day or less to happen, or the seals are totally blown.

Cheers,
Gerry