Transmission Rebuild is Freaking me out! - PeachParts Mercedes-Benz Forum

Jim Sutton · #1 02-07-2009, 09:54 AM

Studying up before beginning my transmission rebuild on my 84 300sd.

But gotta say it looks intimidating.

Can anyone let me know any of the gotcha areas of the rebuild?

Do I really need all of the special tools?

I am looking to improve reliablity and operation in an old transmission. Will I get that or will it be more probable that I introduce more problems than I solve?

About how much would a good rebuild cost me in parts if I do all the work?

I will take pics and post them as the rebuild comes together.

dieseldan44 · #2 02-07-2009, 04:32 PM

Not many here have rebuilt a 722.3xx transmission. They are tough to get right supposedly. You can get rebuilt ones for around $1200 IIRC.

Much of the time, problems with the shifting are due to incorrect vacuum, a broken K1 spring or B2 piston. These do not require a rebuild. (Sorry if you know all of this already). There is a lengthy thread that start with 'its criritcal...' that describes the diagnostic procedure.

I think the transmission is the ultimate in 'if it aint broke dont fix it' systems. If it is shifting somewhat correctly, leave well enough alone.

dd

pawoSD · #3 02-07-2009, 04:49 PM

Yikes, if you're not 100% confident in what you are doing I'd STOP right now and not make a mistake. If it still works, check it out and see if you can solve any issues with simple stuff first. They are extremely precise trans units and require a special skill level to rebuild.

A local shop we brought one of ours too said "we have one guy who does these, and he's the only guy in the area willing to work on one". Other shops send their work to him when they get one in!

leathermang · #4 02-07-2009, 04:56 PM

I don't know what the situation is that is causing you to consider rebuilding..
but if it were me I would get a can or two of Trans-X and follow the directions... and start saving up for a rebuild from a Known rebuilder...
From other MB stuff I think they went out of their way to make stuff require special shop tools... I guess they make big bucks stocking the dealerships with those tools... or don't want to encourage DIY naturally...
Ok, just read pawoSD comment.. agree completely...

Brian Carlton · #5 02-07-2009, 08:26 PM

If you can somehow contact Pete Burton, he'd clue you in on all the details since he's one of the very few who have done it.

He doesn't post anymore, however........

babymog · #6 02-07-2009, 10:01 PM

I'm sure that a DIYer with lots of skill, good intuition regarding a swiss-watch in a case, and exquisite cleanliness can successfully rebuild your transmission.

That being said, I have two friends who own transmission shops, one specializes in high-performance and racing transmissions, he sent his out because his guys weren't comfortable rebuilding it.

Diesel911 · #7 02-08-2009, 12:33 AM

Unfortunately there is not a lot of info available on how to do it. Also when I look on Ebay at Mercedes Tools I see a lot of special tool$ for the transmissions.

However, if you are sure the trans is shot why not take a look inside and post some pics. That way you can get a feel for your ability to do the rebuild.

If you end up having to get a rebuild trans it will be exchanged anyway.

MBNRA · #8 02-08-2009, 11:34 AM

Quote:

Originally Posted by Diesel911

Unfortunately there is not a lot of info available on how to do it. Also when I look on Ebay at Mercedes Tools I see a lot of special tool$ for the transmissions.

However, if you are sure the trans is shot why not take a look inside and post some pics. That way you can get a feel for your ability to do the rebuild.

If you end up having to get a rebuild trans it will be exchanged anyway.

I would find a shop to rebuild yours! You know what your trans is doing and your not getting a trans with unknown problems like you would in an exchange! I've never rebuilt one of these myself and would only feel comfortable doing one in a shop with a trans specialist on duty to help guide me through it.

TchTchr · #9 02-08-2009, 01:03 PM

^^ X 2 on all of the above. In my early twenties, I rebuilt Detroit Allison automatics for Jasper and EVERY transmission I have ever seen has its quirks. If (when) mine goes out, it is getting rebuilt by someone other than me.

81300sd · #10 02-08-2009, 10:43 PM

I did mine and its the first auto trans I have ever had apart. They are really not that tough. One of the clutches I had problems getting the spring retainer off and actually broke one(had a spare) because I thought I could do it without making a tool. Made a tool, had a buddy help me and used an arbor press. Other than that I had to make a deep well 30mm socket for the rear flange.

I also rebuilt the one in my 420(same trans) it took me about 8 hours start to finish including R&R.

If it has more than 200K on it, at least one of the clutches is close to being toast.

Trans X is just a band aid, at the amount of miles these cars get to the trans is just worn out. What other car will go 200k+ without a trans rebuild.

You will be into parts and everything less than $400.

Get a banner kit with all the seals and clutches, cost is ~$200

Find a local trans rebuilder that rebuilds torque converters and have them rebuild yours while you are doing the trans. Mine cost $150

clm · #11 02-08-2009, 11:31 PM

Dont mean to be a stick in the mud, but dont waste your time tring to rebuild it . Any one that knows what ther doing or hasd experience will tell you this.
Save up your money, pull the trans yourself and research around and send it to some one who experienced . Our you will waste time and money!!!!!!!!!

pawoSD · #12 02-09-2009, 12:08 AM

Our local shop will rebuild one for about $875 all said and done. Very good price! They did a full seals replacement for my dad on his 314k trans....$280 and took less than 2 weeks. They said the trans was still in excellent shape inside but did not look like it had ever been opened up before. (at 314k!!!) It does shift beautifully......I hope mine lasts that long too!

I had mine re-sealed by the dealer (or whoever does theirs) back at 213k.....its been perfectly fine since then.....I change my fluid every year too....I'm trying to make it last forever!

rs899 · #13 02-09-2009, 06:33 AM

I don't think transmission rebuilding is any more complex than engine rebuilding. You just need to be able to read a book and follow instructions.
I am rebuilding a 722.3xx for my wife's car now (rebuilt a Ford C-4 a few years ago)

I have some homemade tools I made for the B2 piston spring (modified a gear puller) and clutch packs. I'll post pictures later.

For entertainment, here is a DIY rebuild thread on a ZF transmission, I think from a Land Rover forum. Pretty much the same thing, just to give you an idea.

http://www.x5world.com/x5-e53-forum/57176-transmission-rebuild-pics-do-these-pics-make-you-want-diy-when-comes-time.html

Rick

81300sd · #14 02-09-2009, 08:40 AM

Quote:

Originally Posted by clm

Dont mean to be a stick in the mud, but dont waste your time tring to rebuild it . Any one that knows what ther doing or hasd experience will tell you this.
Save up your money, pull the trans yourself and research around and send it to some one who experienced . Our you will waste time and money!!!!!!!!!

More like anyone that has not done it and is not mechanically inclined enough to tackle it.

Has anyone here chimed in that has actually done it before besides me? I know I am not the only one.

I don't think he needs advice from everyone thats too scared to do it and has no clue on how to do it or how hard it is, he really needs advice from the ones that have done it that can tell him how tough the job is.

Is there anything on these cars that we as a group can not do? No.

Sorry guys but if you are too scared to try something new you will never learn anything, or add to this group.

rs899 good for you. You will have no problems. Be carefull with those spring retainers on the clutches, they are delicate. Everything else is just a puzzle, and not really that big of one either.

rs899 · #15 02-09-2009, 08:49 AM

Voodoo! Voodoo!

That's what the vo-tech dropouts at your local AAmco want you to think....

When you get one of their rebuilds are you sure:

the clutch packs have been fully disassembled and all the hidden rubber seals have been replaced...? New clutch material..or just something used that is good enough for the short warranty...?

every part has been inspected and measured...?

all reassembled parts have been measured per the book and final stackup is correct.....?

These guys get $80/hr shop time. Figure in the cost of parts and overhead and how much care and attention is your transmission getting for $800?

Rick