W109 3.5: distributor renovation

[werminghausen]

Originally Posted by Benz Dr.

I've been rebuildingh distributors for over 20 years and I really can't see why they put it together like that. The earlier have a hardened pin that is driven in with a light spring fitting into a groove that prevents it from ever moving. The spring is one of those feel good items because the pin will never come out.

The distributors with gear drive are different but they really shouldn't drive any harder than a 6.3 or a 300SE. I suspect that they wanted the gear to be very tight so that it would never develope any play given that the tigger points are also timed to the distributor shaft and need to stay in time with everything else. I've seen a number of distributors where the bottom collar became somewhat loose and idle speed timing was all over the place due to loose parts.

Hi Dr.

I think Bosch never intended this shaft and gear to be taken apart...and these germans loved to overdo things.
After all it is just a bunch of crazy guys doing such thing like taking a 40 year old distributor apart in order to bring it back to spec.
It is our appreciation that it is still possible to drive an old Mercedes. This is real style!
Questions:
1) what diameter has the inner pin? 4.0mm?
2) did you ever get this pin out with a punch or would you say ...no way...take a press?
Thanks Martin

[werminghausen]

Update : I was successfully removing the pin today.
I drilled a bit further (4.0mm drill bit) and tried to punch it through and repeated this until the pin moved.
I drilled around 4+ mm deep until it moved.
Here are some pictures.
The pin has a OD of 4.05 and is tapered on both sides from 4.05 to 4.2mm over a length of about 2mm followed by a peened head 4.8mm. I did a little sketch of the geometry of the pin. This means that Bosch did install a 4.05mm pin and was then peening both sides.
Ah I forgot the pin had 3 splines, see picture.
I'll need to get a new pin 4.05mm machined on a lathe when I do installation, the do some peening.
So no wonder that this pin is hard to remove!
I did not remove the gear yet. I'll follow up soon.
Martin

[werminghausen]

I removed the gear wheel. This was easier but also a relatively tight fit.
The gear wheel has the slightly bigger diameter for the end cone.
I will have a new pin machined with 4.05mm and will peen it in place during reinstall.

I took the cam shaft off with the plate mechanism doing the advance.
Here are the pictures. There are 2 Philips screws on the bottom holding this plate. The plate has long holes there. What can be adjusted here? Is it adjusting the advance angle?
I wanted to take the advance mechanism off and check if there is play.
Is this a wise idea?

The distributor has the number 0231 401 003 punched in.
I thought the 3.5 is using 0231 302 001?
Is this the correct distributor?
Are both numbers the same distributors?
I need help here.
Martin

[mercmad6.3]

you wont find those screws in any other brand of distributor. They are for tightening or loosening the tension on the advance springs. By moving them you can make full advance come in sooner or later. Replace the springs with new ones but do not touch the screws unless you have access to the data for adjusting them. I suspect that bosch lost years ago when they disposed of a lot of their paper stuff.I suggest you contact Bosch tradition and ask them if the springs are still available before touching them.
Bosch Automotive Tradition - Parts, Knowledge, Emotions

[werminghausen]

Originally Posted by mercmad6.3

you wont find those screws in any other brand of distributor. They are for tightening or loosening the tension on the advance springs. By moving them you can make full advance come in sooner or later. Replace the springs with new ones but do not touch the screws unless you have access to the data for adjusting them. I suspect that bosch lost years ago when they disposed of a lot of their paper stuff.I suggest you contact Bosch tradition and ask them if the springs are still available before touching them.
Bosch Automotive Tradition - Parts, Knowledge, Emotions

Thanks Mercmad,
You are saying the adjustment is controlling the tension of the springs.
It is not adjusting the advance angle itself, it is just defining at what speed the advance angles are reached. Is this correct?
If true you are assuming if the springs have become weak (well they won't get stronger over the years) the advance will happen at lower speeds than originally defined.
Putting new springs would bring the system back to stock. The second method would be knowing the adjustment procedure and readjust the pretension of the springs.
Does anyone have the adjustment procedure for the advance?

[mercmad6.3]

As i mentioned, the knowledge or equipment required to set the spring tension was probably lost decades ago when Bosch threw out a lot of the paper information they had so your only real option is to contact the above company and get new springs if any are available.
Yes, if the springs get old,they get longer and the ignition full advance will come in earlier.

[werminghausen]

I took the advance mechanism apart and I found the black plastic sheet (where the weights slide on) was broken. Is there a good material to replace this sheet? Any good idea? Benz Dr? and others?

[Graham]

Originally Posted by werminghausen

I took the advance mechanism apart and I found the black plastic sheet (where the weights slide on) was broken. Is there a good material to replace this sheet? Any good idea? Benz Dr? and others?

On my 350sl 4.5L engine, I had the same problem. I looked at some materials for replacement, like Teflon/PTFE sheeting, but it is hard to come by. The stuff that was in mine was some type of phenolic resin sheeting (like Bakelite) which had become brittle. In the end, I just removed the sheeting and sprayed in some Teflon Lube. Seems to have worked fine for a couple of years now. I had thought I might swap with my spare every now and then and relube, but I don't think it is needed.

Don't know if your unit has it, but on my distributors there is a hole down the centre of teh shaft where the rotor sits. There is a felt pad inside and apparently this should get a few drops of oil every now and then. Haven't done that either

[werminghausen]

Thanks Graham,
I might well end up at the same spot: leave the plastic sheet away and let the weights slide on metal.
Yes I have the same lube felt for the advance shaft. Need some atf once in a while. My shaft was seized at some point in time...I can see the marks.
Martin