Upgrading the 722.3 trans
 

I own a 1990 300SEL with the 722.351 trans. The transmission is ready for a rebuild but I would like to upgrade it to handle the additional power of the Mosselman twin turbo I will be installing. The power rating of 300 HP puts it in the ball park of a V8 load on the trans.

What I would like to do is convert it to a 722.350 configuration as fitted on the 560 SEL of the same year. The problem is I have been having trouble determining the differences in the internal hard parts, e.g. drums etc, that I need to accomplish the upgrade. I already have a 1st gear start valve body that also has a shift kit in it so I'm OK there.

The other question I have is that the trans whines (not loud but noticable) in second gear only. Other than that it shifts fine. Any ideas what would cause this condition?

Thanks,
Motor Head

I cant help you on the parts or your problem, but I can almost assure you that a good used 560SEL transmission would be far more cost effective than replacing hard parts in your current transmission, even if you rebuild the used transmission with new clutches and seals.

John Roncallo

That is an excellent idea which is my plan B if what I am trying to do proves to be too hard or too expensive. If I do go that route, I will likely get one thats been freshly rebuilt but at least I won't have to change the configuration.
Now that I have been looking at this for a while it has become a quest for knowledge on 722 technical data.

You will most likely have to swap out the output flange of the 722.35 for the smaller one that your original 722 had. The V8 cars have a 110 mm diameter flange that mounts to the driveshaft and flex discs, where the I6's have a 90mm flange. I'm looking into doing the same thing, and at least from the EPC diagrams that I have found, it appears the swap will work. Most of the part numbers are the same between the two trans, most importantly the bearings and seals that go around the flange.

Hi all, I'm new here been on the benzworld a little bit, got a 560SEC and since seeing PUMPISH M103 set-up am inspired to get rid of the m117 and drop in an M103 or 4 turbo.
On the tranny issue is the bellhousing between the I6 and V8 the same, and the felxplate/ring gear and torque converter and also kickdown cable?

I6 and V8 bell housings, torque converters are Very different.

As an aside, we can rebuild your box with kevlar bands and high performance clutches, valve body springs etc..


Jonathan

Dont get me wrong. PUMPISH has a great car and great work. But may I just ask the question?

Why not do what PUMPISH did to a V8 preferably an M119 V8.

John Roncallo

I agree....for gods sake don't back track! The I6 is a strong reliable motor, but its gonna be HUGE money to get it anywhere close to where you start out with the 560....assuming you don't want the motor to go "bang" after a few thousand miles anyway

May I ask who is we. I would love to find a source of high performance MB transmission parts. Also a good selection of rear end ratios would also be nice.

John Roncallo

We = Me.
http://blueridgemb.com/?p=85

Rear's...that's a bit of a dig..especially one that's going to take the torque of an M120!

Jonathan

Don't sell the M103/M104 short as far as being able to make power.

The stock transmission he has will more then handle a Mosselman TT install.

I'm running a stock 722.358 with 63K miles behind a M103-12V Turbotechnics twin turbo.

Making about 350+ HP and Torque.

Performance is faster then any 4.3L, 5,4L NA AMG V8.
Runs low five seconds to sixty mile per hour.

You don't have to build a 1000HP "hand grenade" that will ultimately explode....

No the 103 is not short on HP but a stock M119 starts life at 315 HP and more than likely more torque over a wider range than your 350HP M103.

My biggest question is this choice is it's application into a 560SEC. The 560SEC is a luxury coupe. When you start to pull 350 HP from a 103 is has to be a whinny screaming engine. In my opinion this type of application into a 560SEC will reduce the value of the car. 450HP can be had out of an M119 without much effort or suffering of drive ability. Or 700 to 1000 HP can be done with a whinny screaming scenario. I believe an M119 installed into a 560SEC will increase the value of the car even with performance enhancements up to about 500 HP as long as the spirit of the car remains intact.

My personal #1 choice for the 560SEC is the M120 V12. See Steve in SoCal sticky on this. If you loose the throttle by wire and MB engine management this becomes an affordable option. But I would put a Chevy 7.0 liter vett engine in as a second choice.

John Roncallo

I was addressing the OP with a 300SEL....not sure how we got to 560SEC and M120 V12...trying to stay on topic !!!!

"Whinny screaming engine".....

You really aren't familiar with the M103-12V if you make such a comment !!!

Max torque @ 4250RPM, max HP @ 5500RPM....very flat curve, no turbo lag, no kick in, starts producing around 1500-1700RPM.

I'm probably close to 400 lb ft at the flywheel @ .48 bar boost on the Garrett T2's.

How does one get 450HP from a M119 without much effort ????

Sure more HP from a M119 V8 but what is your power to weight ratio?


Ed A.

P.S.

My 300CE is also a "luxury coupe"....or at least that is what I was told when I paid 53 large for it in May of 1988...
More expensive then the SL, and second to the SEC.....

My install of a Turbotechnics kit circa 1992 more then meets the "spirit" of the car...
Why?.... because it was an available option installed at delivery by a UK Merc dealer....

No different then dealer AMG mods at the time.

MY 300CE is very "period" and unlike others who
build monster engines that explode, my M103-12V performs like a stock engine from idle to 1500 rpm, including passing emissions controls.
No loud exhaust, just an AMG like V8 rumble on acceleration....!!

Well we got off topic because the OP was discussing a transmission mod only for a 300SEL. Another poster mentioned the 560SEC M103 conversion.

Whinny screaming is a matter of opinion, I could be wrong here it might impress me with Db to power ratio. Lets just call it more whinny and screaming than a larger V8.

Well if we are talking flywheel HP then all you have to do is start it up. If we are talking RWHP then about .6 bar should do it non intercooled single turbo.

Power to weight ratio must be considered as installed power to total car weight ratio. This is one of the reasons the SEC is more favorable to a larger engine. The excess engine weight gets lost in the total weight.

Not in a million years, I left MB in October of 1988, The 560SEC was the most expensive car offered at 77K, 560SEL was 75K, 560SL was 65K. The 300CE was not in the same class with any of these cars.

I'm very sure it does. It sound like a very nice system. The only thing I'm saying is that it would not meet the spirit of the 560SEC or the 560SEL.

John Roncallo

m103 vs m119 "there is no power to weight" differences in those engines.
They are both same weight. Because m119 is alloy and m103 is iron block...