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 Working on air bellows
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Art Love

Australia
6218 Posts

Posted - 02/27/2010 :  08:07:27  Show Profile  Reply with Quote
Today we got stuck into the 300SE W112 coupe which takes us to where this job normally starts. I'm going to do it in a couple of postings because it is getting late and there are quite a few pictures. My younger son was driving this car when the right front suspension "collapsed". Based on his description, I presumed the right front air bag ruptured, but when we finally got it on the hoist, the culprit turned out to be destruction of the nylon ball joint on the right front air valve control rod. It was not connected to the lower control arm at all! You can see why





We started at the right front. Car on hoist, wheels off.





Undo air line to tank using correct tools.





Undo the valve control rod (already done in this case. Undo the DIN 91 screws and nuts holding the piston the the lower control arm. Some sort of right angle flat blade screw driver is necessary to hold the screws while the nuts are undone.









Force the bag up off the piston. This is next to impossible using the recommended method shown.





Brute strength, levering with a screw driver, etc and it is finally almost off. I'll show you what we ended up doing on the other side to make it quicker.













Finally got the damn thing to let go. Undo the nuts holding the tank to the subframe.





Service manual says to undo the steering linkage to get the unit out. We found that we could get it out by turning the steering to full lock without undoing the tie rod. I had also decided to replace the front sway bar bushings, so we had released the torsion bar which would have allowed us to take it out forwards if necessary.





Then we removed the destroyed buffers. Justin drove a flat blade screw driver into the rubber and it levered out quite easilly.









Here is the space you are left with.





On the left, Justin got the bright idea of driving the bag off the piston with a drift once we had it part way released. This proved effective.









Undo the top nuts and remove the unit, same as on the right. More tomorrow.
Art

Edited by - Art Love on 02/27/2010 08:08:15
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Ron B

Australia
11611 Posts

Posted - 02/27/2010 :  15:42:00  Show Profile  Visit Ron B's Homepage  Reply with Quote
The recomended method shows the hammer being used incorrectly,justin has it figured out... if in doubt,use a bigger hammer.

quote:
12-14-2004, 11:49 PM #8
Tom Hanson
MBCA Member

What the heck, try to stuff a MB 6.9 liter V8 in it. What a machine that would be..
__________________
Tom Hanson
Orange County Section
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Art Love

Australia
6218 Posts

Posted - 02/27/2010 :  21:50:47  Show Profile  Reply with Quote
Undo the nuts and remove the unit.









Removed unit can then be bench mounted and dissassembled using a large Phillips screwdriver and a 14mm spanner.









Now the rear units. Wheels off, view from rear on right.





Undo the bolt holding the piston to the trailing arm and dislocate the piston.





Undo the air lines. This is on the left.





Send slave into the boot (trunk) with a 13mm spanner to undo the nuts at the right and left front corners of the floor and another slave into the rear of the car to remove the rear seat base. In the coupe, I found it necessary to remove the seat rear as well. There are two nuts and washer sets on each side. The sound deadener had to be lifted to get to them.









Drop the tank unit down from the floor. On the left, the whole unit came out quite easilly. On the right in the coupe, the exhaust was in the way. We got the right unit out by dropping the front of the trailing arm. Here's the left side.










Here's the right unit going nowhere.





Here is the solution.









Both units are out and you will notice that we did not try to remove the pistons from the bellows on the car. Getting these pistons out is the worst part of this job after many years of use. They really stick to each other where the top of the cone seats in the rubber and steel "lid". The rear pistons are closed at the bottom, so bashing them off the bellows with a drift was not an option.





So I decided to use the same method I used 20 years ago of blowing them off using the rolling action of the bellows. This method only works if the bellows don't have holes in them. I put a Shrader valve into the inlet line of the left tank and used the spare cross line to connect the two units. Other option is to make up a service line with your compressor fitting on one end and a spare end of steel line with screw fitting. You need a larger fitting for the rear tanks if you go that way. I think I put a picture of one of these service lines way back in this thread. If not I'll add it later.





Dissassemble the units on the bench as per the front units.

















Collect all screws, stiffening plates, retainer rings, pistons etc and send to zinc plater for gold zincing. Clean and repaint steel air tanks, buy new bags. Reassemble as per the start of this thread and "bingo" you have rebuilt units to pressure test. Here are a couple of rear units ready to test with 50psi in them via a temporary Shrader valve.





Now they are in the sink.









Locking tabs turned and now they are back on the car, thanks to the slaves in the boot and the rear seat.









Air lines reconnected using proper tools and new washers.









Prepare the rezinced pistons. The Service Manual says to use glycerine as I recall. I used rubber grease.





There is a pin on the bottom of the rear piston that goes in a hole on the trailing arm and the rear pistons are stamped R and L to make installation foolproof.





Screw in the bolt.





On the right we had to reattach the trailing arm.













Wheels back on.









Then we have 4 tanks to clean and repaint for the next job. I am stalled on the front unit reinstallation because the 4 control arm buffers I thought were there were not immediately available and it was getting late. We want to install the buffers before replacing the bellows units.





So that is it for the moment. I hope someone finds it useful. I'm doing a printed version in sections for the Lode Star.
Art
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mtrei

USA
3740 Posts

Posted - 02/27/2010 :  22:06:58  Show Profile  Visit mtrei's Homepage  Reply with Quote
Vascular surgeon Dr Arthur Love demonstrates the latest in pneumatic heart valve technology.


Edited by - mtrei on 02/27/2010 22:09:02
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Art Love

Australia
6218 Posts

Posted - 02/28/2010 :  02:30:45  Show Profile  Reply with Quote
I'd suspect that the technique has more application in urology.
Art
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abl567

Australia
930 Posts

Posted - 02/28/2010 :  04:58:32  Show Profile  Visit abl567's Homepage  Reply with Quote
You taking the piss Art

300SEL
6.3 #2723, my first classic Benz
3.5 #8659, my second.
2 to go...
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Ron B

Australia
11611 Posts

Posted - 02/28/2010 :  17:15:20  Show Profile  Visit Ron B's Homepage  Reply with Quote
No need for viagra with that metal tube,just get your 'assistant'to blow up the bellows when the need arises...

quote:
12-14-2004, 11:49 PM #8
Tom Hanson
MBCA Member

What the heck, try to stuff a MB 6.9 liter V8 in it. What a machine that would be..
__________________
Tom Hanson
Orange County Section
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Craig Tucker

Australia
654 Posts

Posted - 03/01/2010 :  08:26:08  Show Profile  Reply with Quote
With abit more rubber grease, that cathitar (checks spelling)/siposetry could fit almost anywhere. Don't like the "this is going to hurt" smile on the surgeons face....lol.

C.T.

1969 300SEL 6.3 (to be AMG 6.8 replica)
1971 300SEL 6.3
1993 300E-24
1959 220SE Ponton
1983 Schuler 5.0lt Range Rover
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Art Love

Australia
6218 Posts

Posted - 03/06/2010 :  04:51:19  Show Profile  Reply with Quote
The coupe bits are back from the plater.









Justin has been looking for some alternate screws and nuts. The nuts are the thin DIN 439 type.





This is what I am talking about with regard to these thinner nuts. On the left is the old 14mm DIN439, in the middle the current 13mm DIN439 and on the right the current 13mm DIN934.





So as to stop any more lewd jokes about my activities, he has also had some little things made to allow pressure testing without having to use my spare rear cross pipe. Here is a sample of the bits and their application. I'll cover it in more detail in the Lode Star.








Art
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Chris Johnson

USA
3751 Posts

Posted - 03/06/2010 :  10:54:07  Show Profile  Reply with Quote
Art, since you mentioned the DIN 934 nuts, should I assume that these are what was on the tanks when you removed them? Of course, the factory never used DIN 934 nuts in this application.

For the record, DIN changed the 8mm parts (nuts and bolts) somewhere in the mid-'60s such that the span across the flats went from 14mm to 13mm. These 13mm parts started to show up in production in '65, but 14mm parts still show up on cars occasionally even into the late '60s.

DIN also changed the way these parts were marked. Prior to the change, markings were always in the form of "number-letter". i.e. "5S", "6S", "8G", "10K", etc. After the change, markings took the form of "number-dot-number", i.e. "8.8", "10.9", etc.

Folks seriously concerned about originality need to look out for these details when disassembling anything on the car. There was a short period of time when the distance across the flats on 8mm parts had already changed to 13mm, but still had the early style markings. These are the rarest of the rare where hardware is concerned.

Chris Johnson
If you aren't constantly impressed with your car, then it needs fixing.
100.012-12-000790
100.012-12-000867
www.300SE.org
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Ron B

Australia
11611 Posts

Posted - 03/06/2010 :  17:38:44  Show Profile  Visit Ron B's Homepage  Reply with Quote
Pontons are full of those early DIN standard fastners. It often get caught trying to fit the wrong size thread ( but correct size head) .On a W109 a 10mm bolt will be have the same size thread as the next 10mm bolt but on a ponton a 10 mm head may have a 8mm thread. I have bags of bolts from both of my roundies and I have to make sure that the bags are marked to show where they came from. No zinc or cad plating on these older cars either.

quote:
12-14-2004, 11:49 PM #8
Tom Hanson
MBCA Member

What the heck, try to stuff a MB 6.9 liter V8 in it. What a machine that would be..
__________________
Tom Hanson
Orange County Section
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Art Love

Australia
6218 Posts

Posted - 03/06/2010 :  18:36:30  Show Profile  Reply with Quote
Chris,
The 934 nuts hold the metal tanks to the car body work and front subframe which is why I had one back from the plater to use for the picture. I put up the picture to demonstrate the difference. I thought I had mentioned the 439 nuts earlier in this thread, but going back through, I can't see it. I have gone into it in some detail in the Lode Star article Part 1 in the next Lode Star including the typo in one of the Parts Manuals.

In fact, all the nuts on the coupe were correct 14mm DIN 439. What wasn't correct was the total absence of lock plates. On the front, the previous bag changer had used star washers and you can see the imprint of the washer in the 14mm nut on the left of the three in the picture. Whoever did the rears used standard split lock washers. Justin's 6.3 had lock plates and a combination of 14mm and 13mm 439 nuts, probably because some of the nuts had been damaged and had been replaced. On that car, someone had welded some of the nuts!!!
Art
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Chris Johnson

USA
3751 Posts

Posted - 03/06/2010 :  19:28:47  Show Profile  Reply with Quote
I've occasionally seen 934 nuts used to hold the rings to the tank, and it isn't to replace one or two missing 439 nuts. For what ever reason the last guy replaced all the nuts with the wrong ones(?).

Like you, I have also seen these nuts welded to the flat brackets. I can't imagine why. It seems so much easier to just use a DIN 127 lock washer if the original lock isn't reusable. And, of course, the original style locks are, and have always been, available new.

Chris Johnson
If you aren't constantly impressed with your car, then it needs fixing.
100.012-12-000790
100.012-12-000867
www.300SE.org
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abl567

Australia
930 Posts

Posted - 03/06/2010 :  21:19:38  Show Profile  Visit abl567's Homepage  Reply with Quote
Quote "Justin's 6.3 had lock plates and a combination of 14mm and 13mm 439 nuts"

I'm in the process of changing my front bags as well and found 2 13mm nuts and the rest 14mm on the passanger side chamber, they were in one of the tighter spots so I assumed it was due to space issues.

As far as getting the bag through the ring...I gave up trying yesterday and will enlist the help of a much stronger set of hands belonging to one of my staff on Monday


300SEL
6.3 #2723, my first classic Benz
3.5 #8659, my second.
2 to go...

Edited by - abl567 on 03/06/2010 21:20:41
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Art Love

Australia
6218 Posts

Posted - 03/06/2010 :  22:45:55  Show Profile  Reply with Quote
Anthony,
I understand your grief with those air bags. When I did the ones on #1702 15-20 years ago, I recall struggling "for hours" down in my garage on my own using every trick I could think of. Vascular surgeons fingers are not much good for this. Orthopaedic surgeons would be OK. It is great having Justin push one through in a minute or two.
Art


Edited by - Art Love on 03/07/2010 01:31:55
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