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Premium Member
'72 350SL, '85 300D, '98 E320, '19 Subaru Outback (sold '14 GLK250)
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Discussion Starter #1 (Edited)
I was trying to help someone on another forum and it seems the hand drawn diagram (borrowed from Peachparts) we often use when bypassing the DJet switchgear causes some confusion. Radiotek has posted one too but it has the 12v supply from a less than ideal place. I pm'd Scott and he said he will fix that. Then his diagram will no doubt be the most professional one!

But in meantime, I marked up the official MB ignition diagram. Hopefully it is clear. If not, please let me know. The 8kohm resistor is there to get the tach to work properly. Exact value needed may be something like from 6-12kohm. When I do mine, I will likely use a potentiometer (variable resistor) to see what works best.

SWITCHGEAR BYPASSED


Some may wish to use the Pertronix only as a points replacement and retain the original Bosch blue coil and MB switchgear. More simple install as follows:

SWITCHGEAR RETAINED


and

WIRING CONNECTIONS EARLY DJET (with switchgear retained)



PERTRONIX 1885 INSTALLED


Pertronix Install on 1975 Model
The distributor on the 1975 is slightly different, but overall the above diagrams still apply.
The module installation is slightly more difficult. The ways this was solved by michncraig and others are documented in this thread:
http://www.benzworld.org/forums/r-c107-sl-slc-class/1602756-pertronix-install-1975-450sl.html
 

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One of the BW Old Guard/R129, W204 Moderator
1997 SL500- 40th Anniversary
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7,148 Posts
Worthy of EGv107... Consider so moved...

any seconds?

(apologies to any "Roberts Rules of Order", aficionados...)
 

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Premium Member
'72 350SL, '85 300D, '98 E320, '19 Subaru Outback (sold '14 GLK250)
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9,917 Posts
Discussion Starter #3
Worthy of EGv107... Consider so moved...

any seconds?

(apologies to any "Roberts Rules of Order", aficionados...)
I would be happy with that - even if I am the only one ;)
 

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R/C107 Moderator
1986 560SL: '84 500SL: '84 280SL 5 speed: other 107s
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31,708 Posts
I think it is a good idea. Maybe Scott will contribute a Crane diagram.
 

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Premium Member
'72 350SL, '85 300D, '98 E320, '19 Subaru Outback (sold '14 GLK250)
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9,917 Posts
Discussion Starter #6 (Edited)
I think it is a good idea. Maybe Scott will contribute a Crane diagram.
The thread on the 1975 Pertronix Install is useful and I should provide a link to that with my diagrams.

That thread includes Scott's diagrams for Pert and Crane. But he shows the 12v supply after the two resistors which are shown in series. Scott said he would correct that. Pertronix needs full 12v.

ADDED: Link to 1975 install added to first post.
 

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Premium Member
'72 350SL, '85 300D, '98 E320, '19 Subaru Outback (sold '14 GLK250)
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9,917 Posts
Discussion Starter #7
Someone asked for step by step instructions on installing the Pertronix as a points replacement in an early D-Jet (72,73) , so here goes.

Buy a Pertronix 1885 kit.

- Remove distributor cap.
- Remove rotor and put aside.
- Remove points and condenser as well as green wire.
- Note where green wire was connected (terminal near resistors below coil)
- Slip the magnet that came with kit over distributor cams and push down until it is fully seated.
- Install pickup coil from kit approx where points were (see picture above)
- run the red and black wire through the rubber seal at back of distributor and find a route to near resistors below coil. You will likely have to extend the wires to reach.
- Connect the red and black wires as depicted in earlier diagrams and in this picture
- Get a new piece of wire, preferably brown. Add connectors and attach this to the outside of the distributor(there are soms crews you can use) or inside if you can find a good point. This is a ground wire. It should go to any good engine ground or to the battery negative. There is a ground terminal under air cleaner as well as just below HT coil (brown wire goes to it)
- Replace rotor and cap.
- Have fun.

Points replacement only has no affect on tachometer.

Only thing to remember, is not to turn ignition fully on for long periods of time. If you need to, disconnect the red Pertronix wire.

Much of this is same if you are bypassing switchgear, but wiring is of course different
 

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Registered
73 450SL
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6 Posts
Hi guys,

I enjoy this forum so much, and thank you all for contributing your knowledge to help others. I'm at a cross road on my 73 450SL. My car is pretty much stock on all, and the Ignition Control Module or Switchgear is dead (to be tested for sure). I have no sparks at the plugs. I use the car as my daily driver and have not had any issues with the exception of the vapor lock problem here and there. I could not get the car start when i tried to leave work last week. Had it towed home, and i have tested the Borsch HT coil wire, it's good with 5K ohms. I thought that the old coil is bad and replaced with a brand new one. Well, it turns out it wasn't the coil because the new one produces no sparks too. :( I know i moved too fast in replacing the coil. Anyway, after replaced the rotor, spark plugs which all need to be replaced, and coil i still have no sparks. Most likely now the Switchgear is dead. I will do some testing tomorrow to confirm.

I have searched eBay and find some used Borsch ignition control module that matches my unit model, and the cheapest on a used unit is $170. So here are my questions:

1. Should i just get the Pertronix 1885 module and the FlameThrower coil 40011 and forget about the MB ignition control module?
2. I see MBGraham posted a diagram with the MB Switchgear completely bypassed. Is that configuration working well for a 73 D-Jet 450SL?
3. Any other recommendation for me based on my situation at the moment? I don't mind spending a little extra to have a maintenance free piece of mind.
4. I contacted Pertronix and inquired on any replacement and they suggested that i give them the model of the distributor and they can cross-reference a replacement that i can use without the Switchgear. Does anyone know what distributor they are thinking of? I check and think that they are thinking about the "Stock-look" Cast Distributor. Here is the link to the unit. http://www.pertronix.com/prod/ig/flame/dist/cast/default.aspx I'm planning to find the model number and see what Pertronix is thinking of.

Any thoughts? Many thanks guys!
 

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R/C107 Moderator
1986 560SL: '84 500SL: '84 280SL 5 speed: other 107s
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31,708 Posts
They probably want the Bosch part number stamped into the distributor body. Have you checked the points? How about the green wire and the wires/plug to the trigger points? Also the condenser.
 

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Premium Member
'72 350SL, '85 300D, '98 E320, '19 Subaru Outback (sold '14 GLK250)
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9,917 Posts
Discussion Starter #11 (Edited)
Like Rowdie, I noticed you did not mention the points. They should have about 0.014" gap.

Again as Rowdie mentioned, make sure the green wire that runs from the distributor is not grounding out anywhere and is properly connected at the connector down near the resistors below the coil as well as within the distributor. If there is a condenser, it can be eliminated (Mercedes suggestion!)

If in fact your switchgear IS bad, just buy a Pertronix 1885 and a Flamethrower coil and install as per the upthread diagram (I am assuming your new coil is same as old Bosch coil, which is not suitable, but other types may be.)

Pertronix are not always that helpful when it comes to our old Benzes. They are looking for a Bosch part number that is stamped on your distributor. But really, you don't need to bother. Just get the 1885. Ignore most of the instructions that come with it and you will be good to go! You will probably have problems with the tach. But that is also covered in earlier post.

Even if you find that the switchgear is not bad, installing just the 1885 as a points replacement is a good first step.

Good Luck

PS: That Stock Look distributor is not intended for these cars.
 

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Registered
73 450SL
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6 Posts
They probably want the Bosch part number stamped into the distributor body. Have you checked the points? How about the green wire and the wires/plug to the trigger points? Also the condenser.
Hi Rowdie,
yeah! they want the Borsch #. I checked but only see the Borsch Made in Germany. i'm sure the model number is on the other side that requires the removal of the distributor to read... :(
Does anyone has a cross-reference on Borsch distributor model # for a 73 450SL?
 

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Registered
73 450SL
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6 Posts
Like Rowdie, I noticed you did not mention the points. They should have about 0.014" gap.

Again as Rowdie mentioned, make sure the green wire that runs from the distributor is not grounding out anywhere and is properly connected at the connector down near the resistors below the coil as well as within the distributor. If there is a condenser, it can be eliminated (Mercedes suggestion!)

If in fact your switchgear IS bad, just buy a Pertronix 1885 and a Flamethrower coil and install as per the upthread diagram (I am assuming your new coil is same as old Bosch coil, which is not suitable, but other types may be.)

Pertronix are not always that helpful when it comes to our old Benzes. They are looking for a Bosch part number that is stamped on your distributor. But really, you don't need to bother. Just get the 1885. Ignore most of the instructions that come with it and you will be good to go! You will probably have problems with the tach. But that is also covered in earlier post.

Even if you find that the switchgear is not bad, installing just the 1885 as a points replacement is a good first step.

Good Luck

PS: That Stock Look distributor is not intended for these cars.
Hi MBGraham,
yes, i check the point and the green wire. All look good. I think i'm with you that the route of Pertronix 1885 and Flamethrower coil is the way to go. In reading other posts on shimming the magnet of the Pertronix piece, i guess the objective is to get the magnet to be at the same height has the electronic point, right?

Does anyone has a confirmation on the value of the resistor needed to get the tach working right? i'm reading from no need to less than 10K ohms.
 

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Premium Member
'07 ML350, '05 ML350SE, '04 ML350, '01 ML55, '05 SLK350, '04 SLK200, '76 280SL
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Premium Member
'72 350SL, '85 300D, '98 E320, '19 Subaru Outback (sold '14 GLK250)
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9,917 Posts
Discussion Starter #16
For anyone monitoring this thread, can you have a look at the below thread please and offer any help :

http://www.benzworld.org/forums/r-c107-sl-slc-class/1909649-280sl-loses-power-after-about-25km-6.html#post8682897
I am no electrical wiz, and I still have not gone to the complete switchgear replacement on my car, so lets see what the autoelectric experts say!

Have you tried running without the tach line connected at all?

I don't know that you have a need to ground through the tach. I would have thought that the tach would just count pulses as the Pert opens and closes and fires the coil.

I see you used a Pert II. I was under the impression that we should use Pert I's on our Benzes. Pertronix say on their website that Pert II is not suitable for use with the solid copper ignition wires that we have.
 

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Registered
1972 350SL 148,000 miles
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7,013 Posts


When I installed my Pertronix according to this picture (which I'm pretty sure I took and labeled some years ago haha it works perfectly including reading RPM's, I just disconnected the green wires from the dist, plugged them in where indicated and -everything- works, including tach, so I guess I'm using the switchgear as my resistor, WTH I'll take it

This was the second time I did the Pertronix install with the flamethrower coil, first, the improvement is immeasurable, I can't even begin to describe how much better it is, I always had to compromise with dwell to get max performance, either I set it to spec and got it to idle perfectly but -not- -quite- -right- at higher RPMS, or I dropped it down to the mid 20's and got super performance but shit idle and it had a traveling stutter that moved with the dwell, at 24 it was exactly at idle, at 27 it was at 1200, and at 30 was at 1500 RPM's, I spent -years- trying to track that gremlin, new distributor, dist cap, rotor, condenser, points, literally years, and it remained no matter what I replaced, with the Pertronix installed, it's all moot (I've found MUCH better performance bypassing the switchgear and installing the flamethrower, but it's only my experience.

I can't recomend these strongly enough, it took me two hours of prep and 20 minutes to install.
 

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Premium Member
'72 350SL, '85 300D, '98 E320, '19 Subaru Outback (sold '14 GLK250)
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9,917 Posts
Discussion Starter #19 (Edited)
THis may be a repeat of first post (put in because of Dropbox problems), but I will leave it here anyway.Pertronix Install with and without Switchgear
I was trying to help someone on another forum and it seems the hand drawn diagram (borrowed from Peachparts) we often use when bypassing the DJet switchgear causes some confusion. Radiotek has posted one too but it has the 12v supply from a less than ideal place. I pm'd Scott and he said he will fix that. Then his diagram will no doubt be the most professional one!

But in meantime, I marked up the official MB ignition diagram. Hopefully it is clear. If not, please let me know. The 8kohm resistor is there to get the tach to work properly. Exact value needed may be something like from 6-12kohm. When I do mine, I will likely use a potentiometer (variable resistor) to see what works best.

SWITCHGEAR BYPASSED



Some may wish to use the Pertronix only as a points replacement and retain the original Bosch blue coil and MB switchgear. More simple install as follows:

SWITCHGEAR RETAINED


and

WIRING CONNECTIONS EARLY DJET (with switchgear retained)



PERTRONIX 1885 INSTALLED



Pertronix Install on 1975 Model
The distributor on the 1975 is slightly different, but overall the above diagrams still apply.
The module installation is slightly more difficult. The ways this was solved by michncraig and others are documented in this thread:
http://www.benzworld.org/forums/r-c107-sl-slc-class/r-c1...975-450sl.html
 

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Registered
1999 SLK 230, 1973 450 SLC
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69 Posts
Late to this party

Thanks for the great resource.

I put in the Pertronix 1885 today. Followed your wiring instructions. I saw that the magnet wasn't lining up with pick-up and added the water hose gasket under the magnet to align. (Think I saw that in the 1975 Pertronix link.) Along with that I took off a 1/4" of rotor for clearance. Fired up instantly.

Tomorrow I'll add the Flamethrower coil and check timing.
 
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