Transmission Quandry
 

The 722.3 transmission on my 1981 380sl with app. 200k miles on it is starting to slip in reverse, and my research indicates that the slipping is due to a worn B3 clutch pack that has no external adjustment.

However, a local transmission specialist, who seems to know quite a bit about these trannies, suggested that he might be able to remove or significantly delay the problem by adjusting the "reverse servo," which can be accessed externally.

My question is "can reverse on the 722.3 be adjusted this way," and if not which of the following would be my best option:

1) Have him or another specialist rebuild my B3 clutch and inspect the rest of the unit for app. $750 including parts and a 6 month warranty; or

2) Replace the existing tranny with a used one with app. 100k miles on it from a local salvage yard for $400 + $350 for a specialist to install it. Although this used tranny would have a 90 day warranty, if it ends up being defective, I would have to pay another $350 to have it removed and replaced with God knows what.

Of course, the best thing to do would be to have the whole unit rebuilt for app. $1650, but the cost of doing that is prohibitive at this point.

Thanks very much in advance for your, usual, well-informed opinions.

Steve

There is no external B3 adjustment on the 722.3 transmission. The problem is normally a clutch pack where the friction material has flaked off for some reason. Also the reverse piston may have a crack in it and/or the piston seals have gone bad. Best thing of course is a full rebuild, but the B3 clutch can be taken care of by itself. The transmission has to come out for that.

The used transmission most likely will have a B3 clutch that's questionable, so that's a roll of the dice.

I think the transmission your guy is referring to are the 722.0/722.1 units which use a band for reverse that's at the front of the unit with an externally accessible adjustment. The 722.3 uses a multiple disc clutch instead of a band to do the same thing.

Stay away from that trans shop..no external adjustments on LB3.

Stick with your current transmission and just do the b3 bands. Go to another shop as mb doc said. No adjustments. The transmission must be removed.

A used transmission is a major gamble. One that in the long run may cost you more.

More info here:
http://www.w124-zone.com/articles.php?article_id=21

What ps2cho said-

The B3 bands are really not that far in once you get the transmission wrestled to the ground. Problem is, at 200K you are about due for the rest of the clutch packs to be redone... although its really not all that hard to do the whole enchilada.

Rick

After considering the amount of work doing the job myself would require, I opted to have the local transmission shop remove the tranny, and replace the B3 clutch pack and seals, along with anything else that needs replacing, in the hope that I'll be able to get another 150-200k miles out of it.

Although he evidently made a mistake about the possibility of adjusting the B3 on 722.3 externally with earlier versions, I still feel confident that he knows what he's doing, and his price -- $750 for r & r'ing the B3, and no more than $1350 for a complete rebuild, if necessary -- was very reasonable.

Of course, you never know what problems may arise, but the fact that his shop is local and has been in business for 20+ years without any BBB complaints gives me a sense of security that he'll stand behind his work for a reasonable period of time -- which is all one can really ask for in these cases.

However, thanks very much for the very helpful responses, as it helped me make a far, more informed decision than I could have made.

Make SURE he reseals the front pump. You do not want to have to pull it again if it starts dumping fluid everywhere.

B3 bands + reseal front pump is sufficient to keep you going. You can also opt to use higher quality transmission fluid since he will be completely draining it.

I highly recommend Redline Synthetic D4. It is the best fluid for the 722.3...hands down. I don't recommend synthetic for these older engines, but this fluid for the transmission is king :)

Well, I just test drove my car after having the entire transmission rebuilt, and the problem I brought it in for is still there; namely, when I put the shifter into reverse when the car is hot, I can feel and hear the transmission whirring for a few seconds afterward. However, when the car is cold, there is no whirring, and the transmission goes into reverse as quickly and firmly as it goes into drive whether the car is hot or cold.

Now, the people that rebuilt the transmission are telling me that the whirring in reverse is normal, even though they told me that the car was indeed slipping in reverse when they test drove it. Am I wrong in believing that the whirring is not normal, and should be characterized as "slipping in reverse?"

In any event, I've owned this car for over ten years now, and I believe that the whirring, which only began a few months ago, was getting progressively worse -- which is why I brought the car in the first place.

Moreover, a number of threads in this forum revealed, or at least strongly suggested, that the problem was caused by worn B3 clutches. Yet, the rebuilder told me that he replaced those clutches, and that the old plates still had about 40% left on them -- in which case the problem, if it really exists, could be caused by a worn bearing in the planetary gear(?), which he didn't replace.

So, I'm left with trying to decide whether the whirring I brought it in for was in fact normal and was always there, but that I never noticed it; or whether some part of the transmission was indeed going.

In addition, I'm left with the problem of trying to decide what to do if the rebuilder -- who, at least, agreed to keep the car and look further into my complaint -- insists that the whirring is normal.

Thanks very much in advance for any additional advice anybody can give me on the best way to solve this problem.

Rule #1 You never take a mercedes benz transmission problem to a transmission shop, that doesn't totally specialized in mercedes benz transmissions. If you do you are going to loose every time. An honest transmission shop will turn the work away, because of the different intricacies of the transmission. A mercedes shop has all the equipment to hot test them, and there good before going back. The post that said bypass that transmission shop was giving the strait truth on the issue. Don't ask me how I know!

What Rebe said....

Whirring is not normal.

Also, why didn't you mention whirring in the initial post? All you said was reverse slippage. Our diagnosis was correct based on what you gave us.

I don't know of any transmission shop in the Philadelphia/S. Jersey area that specializes in MB transmission, and all the shops I questioned said that they were familiar with them. Do shops that specialize in MB transmissions really exist, and if so, where?

I allowed this shop to rebuild it, because the guy who runs the shop assured me that he had rebuilt a large number of MB transmissions over the 20+ yrs he's been in business, and the guy who actually did the bench work convinced me that he was very familiar the 722.
In addition, the owner had test driven my car, and agreed that it was slipping in reverse, and the price he gave me for rebuilding it was so much better than anybody else's.


Thank you. I didn't think so.

I said the transmission was slipping, because I believed that was the best way to characterize its failure to access reverse, and the whirring sounded like the whirring someone else explicitly mentioned and called slipping in this thread:

http://www.peachparts.com/shopforum/showthread.php?t=153734&highlight=transmission+whir

Moreover, since a number of other people had reported problems with reverse, but not other gears, in their with 722's, I concluded that I was having a similar problem.

So, now that you guys know that it's whirring when I put it in reverse when it's hot, but not when its cold or when I put it in D, N, or P, does anybody have any idea what it could be -- considering that the transmission was just rebuilt, and all the clutches were changed?

Your help would be greatly appreciated, as my car is still in the shop, and I'd like to have some idea as to what could be going on.

Did he replace the hidden O rings at the base of the clutch baskets? If you don't do that, the leakage will not allow the clutches to fully engage. To replace the O rings you have to drill out several rivets to get to the O ring. You then have to tap the rivet holes and put in a flat head screw. Ask him if he did that.

Those O-rings are for clutches K1 and K2; they won't affect reverse at all.
Not all overhaul kits come with the K1 and K2 repair kits with the screws and O-rings. Really not sure what the OP is hearing in his transmission without seeing it for myself. Is it something that slows down as the transmission engages?

The whirring occurs when I put the shifter into reverse when the car is hot, and it's more tactile than audible, though I can hear it. It's gone once the transmission engages, and as I mentioned, it never happens when the car is cold, or in D, N, or P.

So, my guess is it has something to do with heat lowering the viscosity of the transmission fluid, which is now Redline, or expanding something, making it difficult for the transmission to access reverse (?).

Thanks very much for the continued concern. It's greatly appreciated.

Isn't there a seal around and in the middle of part #14 in this diagram?

http://www.jie.com/Mercedes/w4a020Sch1.htm

Anyway, there is a seal somewhere in front of the B3 clutches that actuates them- I have forgotten what works them, but I would guess that they didn't replace it and it's leaking when the fluid is hot and thin.

Yes, it's 12 and 13 in the diagram. They're the inner and outer piston seals. I don't have the transmission manual available here at this time (it's on a computer that is down at the moment) but I remember something about noise in reverse possibly being caused by the B3 piston having to move further than normal and contacting rotating parts of the transmission. This is normally due to excessive B3 clutch wear, but could also be an assembly error. It happens to the best of us when working on transmissions

Thanks very much for these extremely detailed responses. However, if the problem was originally caused by worn B3 clutches, as other threads led me to believe, the new clutches should have corrected it.

And, imo, its unlikely that the problem was caused by an assembly error during the rebuilding, because the transmission has the same problem it had before I had it rebuilt.

As for the possibility that the problem was originally caused by leaking inner and/or outer piston seals, I just assumed that those would have also been replaced as part of the rebuilding. But if they weren't, and were in fact leaking, that could account for the problem.

In any event, they still have the car, but I can't get in touch with them because of the snow that just hit Philly. However, I'll ask them about these things when I do get in touch with them.

In the mean time, if anybody has any other ideas as to what may be causing my problem, they, too, would be greatly appreciated.

The seals in question are illustrated somewhat in this guide:

http://www.w124-zone.com/articles.php?article_id=21

You can find this passage about 60% through the writeup...the piston is the picture just below this quote:
There's a huge o-ring seal around it and a lip seal in the center of it. Five pictures down from it you can see it's backside, without the seals on it.

Thank you. I see what you're talking about but, since I wasn't there when they rebuilt the tranny, I don't know what they did or didn't replace. OTOH, after talking a bit to the bench-man who actually rebuilt it, I came away with the impression that he had rebuilt many of these, and knew exactly how to do it. So, that's why I left it there.

I'm just hoping that they'll take the time to remove it, and see why it's still doing what it was doing when I brought it in, and, hopefully, we won't have to get into a dispute as to whether it's behaving normally or not.

Let me say again that I really appreciate the concern you and other very knowledgeable people have shown me here. These boards have obviously made it so much easier for people to get good info about these things than ever before, and I can't imagine what I would have done without this one :).

Just a suggestion fwiw. If on going back to check on the vehicle, and it is still is not correct or to your liking. You could make a ploy to get your money back, because of your dissatisfaction. If they are like your impression of them has been, this should no problem. If they hedge on it, you might deal with them on getting it correctly else where, and they refund the monies it took to make it right. Then you can move on from there one way or the other.

Thanks for the suggestion, but it won't be necessary since I haven't paid them yet.

In addition, after taking the tranny out, disassembling it, and getting advice from someone who evidently knows even more about these trannies than they do, they've concluded that it is what I think the owner called a "regulation" problem caused by a leak in a valve or seal in the valve body(?) So they're going to replace the valve body.

I don't know what a valve body costs, but when I asked him, he led me to believe either that he's going to absorb it, or charge me what he paid for it. Any of you guys know how much a valve body costs wholesale, or whether my problem could have been caused by a leak in or failure of something in the valve body?

And thanks again for the help. You guys have been absolutely amazing.

A valve body problem is also possible, I guess, and that is much more correctable at this point without dropping the transmission. I have no idea what a valve body costs. Probably $1000 from Mercedes, $10 on ebay from somebody who has one lying around. Valve bodies are specific to applications- for example the valve bodies from a 722.315 diesel will work differently than the one in yours for a 380SL 722.3xx.

There's no reason to think it needs to be replaced rather than carefully cleaned, IMO and then the various upgrades can be done at the same time.
If it is disassembled, follow the instructions carefully ( especially about flipping it over when separating the halves- don't ask)

Thanks for the additional advice, but I think the rebuilder already opted to replace it with a rebuilt one, without giving me the option.

Last three questions, hopefully:

1) Should the transmission shop have been able to determine that the problem was in the valve body, rather than the B3 clutches, seals or pistons, when I described it to them, or they test drove and pressure tested it, as they were supposed to? (I hate to think that the problem could have been solved simply by replacing or rebuilding the valve body, rather than the whole transmission.:()

2) Since the shop said that they had to rebuild the transmission to solve the problem, and they gave me a price that presumably included the labor and parts for doing that, should I now have to pay for them to buy and install the valve body?

3) AFAIK, this transmission hadn't had the fluid replaced until I did so app. 40-50k miles ago, when the transmission must have had app. 150k on it. Considering that some people have said that changing the fluid in such a transmission can create problems by removing varnish on seals and other parts, is it possible that the fluid change I performed ended up causing my problem? (I hate to think that it did.:()

Thanks in advance for also answering these questions for me. You guys have been absolutely tremendous.

1) I really don't know . I for one, am not smart enough to positively diagnose something like this. I have only rebuilt one more of these than you have :)

But- did they fix it with the valve body change?

2) I would say no- you told them what the problem was up front, they offered to fix it via a rebuild. They didn't fix it as contracted.

3) Remotely possible, but I would have done the same thing.

Rick

The front pump most likely needs replacing. The whirr sound is the pump trying to keep the torque converter full.

Daddi might be onto something....but of course....

This should be known already because they should have taken the front pump apart to REPLACE THE FRONT MAIN SEAL. Any repairshop who does not do this every time the 722.3 is removed is not the right person for the job.

Again, make sure the front pump has been resealed. It must be done and when it is done, the pump gears should be inspected since it is apart anyway.

After having similar problems, and making a few phone calls to rebuilders (who all claim to be experts) I spoke to my MB dealership. They dont do rebuilds any more, they just order a genuine MB rebuilt and slap it in. I did not need a converter so $3100 for the trans, plus hoses, trans mount, and labor with 2 year 24 mo warranty

In reality, that's actually not too bad of a price for a completely rebuilt from MB....

I haven't gotten my car back yet, know the cause of the problem, or the price of fixing it. So, the jury is still out as to whether rebuilding it was the way to go, and whether this shop knows what their doing.

When I do know the answers, I'll post them. That way those people who have been trying to help me answer these question, and others who may have the same questions, can benefit from my experience.

In the meantime, thanks for the recent responses.

Any news?

Happy ending?

Believe it or not, I still haven't gotten my car back:mad:. They ordered a rebuilt valve body from their supplier, but there's apparently two different versions, and they got the wrong one.:confused: So, as of yesterday, they were installing the correct one, and were going to thoroughly test it to make sure it was working correctly.

In retrospect, I wish I had gone with the used one, as this is exactly the can of worms I didn't want to open up.

Thanks for the continued concern:).

Well, here's the latest installment of this seemingly, never-ending saga. The shop owner told me today that they had installed the rebuilt valve body and reverse was now engaging correctly.

However, the engine is flaring when it shifts, and they can't get the flaring out by adjusting the existing modulator, because it doesn't have the pin that MB added to later versions. So now they're waiting to get and install a new modulator. :mad:

Does anybody happen to know if this will correct a flaring problem?

every shift is flaring????

He didn't say, Lee.

Bump
 

for customer