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Hello everyone, i have been searching around but have had a hard time finding concrete info. My 740 shifts fairly hard between gears, it sort of 'bangs' them if im giving any gas, but still shifts hard even with out a lot of throttle applied. i have changed all the fluid and cleaned the screen in the tranny, i believe the tranny is a A71?!?! it is the stock tranny and i think that is what should be in the car. The car has been great but i will be leaving to go to NH and i am debating if there is a good chance this tranny could 'let go' while im on the trip, in which case id just bite the bullet and fly up.
what do you guys think? the car probably has ~200k on it, but it was driven by and older man and his wife, so the miles have not been that hard, yet there has been quite a lot of them :) any info would be great! Thanks, bill
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It's unclear from your post as to whether or not the hard shifting represents a change in your transmission performance. Turbo model autos have a modification that results in much crisper shifts than the NA models. Have you driven any other turbo model 240-740-940? My understanding is that there are chambers with "pistons" within on the NA cars that cushion the shift--these "pistons" are deleted on turbo models. -- Dave
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Bill,
Are you sure it's your tranny banging and not the drive shaft bouncing in its rubber mount?
You said you changed all the fluid. Does that mean you did the trans flush per the 700/900 FAQ instructions? If you just pulled the plug/pan and refilled, then you only changed about half of it. Also check the kick down cable per the FAQs.
You are asking if the tranny can make it to NH, but you didn't say where you are starting from. Are you starting from Vermont or from California?
Either way, yes of course the tranny can let go at any time. But, if you are afraid to drive it, you need another car. That was the mindset I took when I drove my 300k miles Benz on a 6500-mile trip, and it made it just fine.
Charley
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Charley, thanks for the response i guess i did leave some info out, i am down here in SWFL. im pretty sure its not the driveshaft as the car pulls/feels faster during the shift, not literally a 'bang'..... i did a complete flush by removing the return from the oil cooler and draining fluid out while adding fluid to the tranny, i did get the info from the FAQ. i read about the kickdown cable, but was under the impression that it controlled more of the shift points, not the shift it self. thanks for all the help, what kind of benz has the 300k on it? i would guess an older benz, i think they were built much better back then
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Bill,
I'm not really getting a good sense of what you are feeling, so it is hard for me to make a guess. A driveshaft bouncing in its rubber mount makes kind of a dull thump sound/feel (maybe several of them) on upshift, and the sound/feel comes from the trans tunnel.
Is it shifting late (at more than normal road speed/RPM)? If so, the engine is higher up in the power band and may cause more of a jolt when it shifts. This could be caused by the kickdown cable needing to be freed up or adjusted.
Do you know anyone familiar with them who can drive it and give you an opinion?
Yes, the Benz was an 83 300SD turbo diesel.
Charley
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i definitely dont hear a clunk from the drive tunnel, i would describe it as popping the clutch between 1st and 2nd when shifting a manual (only without it stalling obviously) And unless i am giving it a lot of gas it does not shift that high in the RPM's... i can feel the kickdown cable at the end of the throttle and it seems to work when i press hard enough to 'activate' it. I have always wanted an old MB diesel to convert to veggie oil... but have been afraid of the cost of parts.... do you have any advice if i was going to look for one? any particular model?
thanks
bill
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Bill,
If it's not the drive shaft and not the kick down cable, I'm stumped.
For a Benz to convert to veggie, or for any other reason for that matter, the FIRST choice is a 1982 to 1985 300D or 300SD. The SD is bigger, so it may be easier to pack in the veggie equipment, and they are less prone to rust compared to the D. If you want a wagon, then a 1982 to 1985 300TD is good. But, the wagon has a complex load leveling hydraulic rear suspension. The load leveling would be nice for packing extra weight, but you add potential problems and you probably would not want the extra fuel tank in the passenger compartment.
You can go older than 1982, but you won't get the turbocharger on the 300D, and there are some minor differences on the 300SD that can make spare parts less available. You can also go to a 240D (4-cylinder instead of 5), but there is a power loss. I would not go older than late 1975 for a 240D or 300D because you get into a different chassis and parts will be less available.
Parts prices on Benz is helped by the fact that you can buy individual parts for them while on other cars you might have to buy an entire assembly. For example, I bought the part inside the glove box latch that had failed for about $2. On most cars you would have to buy the entire latch or even the entire glove box door.
Charley
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i can't help much on the shifting , but i've owned 5 MB diesels , mostly beaters. Excellent, very reliable, almost indestructible go for 300 series 1980-1990. parts are not any worse than other cars and they are fairly easy to work on. Actually quite simple. As you get into late 80s they have more computer stuff to deal with. A/c can be finicky and expensive. The MB 5 cylinder diesel are the strongest engine know to man IMO. I've bought a few off ebay and some locally. Watch auto trader in fl and there a place in FTL that sells specializes in them Mercedes showroom.. Honest folks ' not the cheapest, but you get what you pay for. good luck.. Only volvos and mercedes for me baby
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