Experience with Retrofit Blade Fuse Panels for 69-73 911

[ProfHollan]

I would appreciate advice from anyone experienced with installing a Classic Retrofit blade fuse panel in 69-73 911. I am considering for 73 911E. The provided manual only covers 74 and newer cars. Looks to be more straight forward on 74 and later cars because of panel location.

[majordad]

Have a look on the DDK Forum, lots of the members have done it and the guy who makes the item often posts.

[911GP]

I had it fitted during my restoration. It was straightforward. Just note that it does not look like the original type with the black screw covers. It has a smoked Perspex instead so you can see the leds flash when a fuse has blown. I also had the small engine bay block fitted and their CDI+.
Here is a good write up on DDK.:

https://www.ddk-online.com/phpBB2/vi...assic+retrofit

[ProfHollan]

Thanks for the pointers.

[raspritz]

I had not heard about this before, so I read up on it. Why do you want to do this? It isn't cheap, there is no performance improvement, there is no real utility improvement, nobody but you will ever see it, and it reduces authenticity of the car. I don't see the point.

[ProfHollan]

I appreciate the authenticity argument. Still, the industry does seem to be moving to blade fuses and they are said to be less subject to vibration loosening and intermittent contact than spring-loaded. A perhaps more compelling reason is the nice design of the Classic Retrofit panel to include LEDs to indicate failure. In any event, my query was mainly to get advice. I appreciate the responses. Interesting that the blade retrofits seem to be more popular among Porsche owners in Europe than the US.

[uai]

I had not heard about this before, so I read up on it. Why do you want to do this? It isn't cheap, there is no performance improvement, there is no real utility improvement, nobody but you will ever see it, and it reduces authenticity of the car. I don't see the point.

+1
Although I have to admit that I used some flat blade fuses in my car in hidden places. But this is a (non Porsche) car that has 6 fuses by default and I just needed more than those 6 to accommodate the additional stuff like hidden usb charger dual electric fuel pump, wideband o2 sensor etc..

...are said to be less subject to vibration loosening and intermittent contact than spring-loaded..

They were used for 50+ (even much longer if you count the shorter variant) in nearly all cars... They just work. I can understand if using for an upgrade but not as a replacement with the same amount of fuses.

[ejboyd5]

A lot of work and unneeded expense for very little benefit. If it ain't broke . . . You would be further ahead by assuring that the car does not have aluminum fuses.

[VintageExcellen]

Out of hundreds of 65-73 911 cars through my hands I have never experienced shortcomings in the original fuse boxes, except they are Bakelite plastic which can be brittle if you are all thumbs and clumsy when handling them or putting the fuse boxes in. There has been the odd burnt terminal but that was always due to user errors not normal wear. The industry is also going to micro wire and relays galore but I don’t see the benefit for our cars. CR has some cool CD boxes and electric a/c products. No need to switch unless you are one of those people that has to modify everything. 90% of the time you will never go wrong going back to stock original.

[G69]

If any of the fuse's terminal posts with the crimp screws are loose in the fuse block that fuse block needs to be serviced or if available replaced.

A rivet underneath as part of the post not only locates the post it also provides electrical continuity where posts are jumped together with brass strips on the underside to share current. If the post's rivet is loose it not only may not work- it can overheat.

The rivet that ties the post to the brass conductor strip on the underside may also be 're-set' carefully to tighten it up and insure there is no electrical resistance between the post and the strip.

You likely have something in your tool chest that can be used to re-peen the rivet.
I used a 1/4" socket extension that had a similar contour to the rivet.
This is where a small ball peen hammer is key. Backing up the post with the screws removed is crucial. Go easy. The 50 year old block is very brittle.

Then insure that all the fuses are ceramic with real copper filaments. Plastic fuses even with copper filaments may distort with a little heat.
That little movement from expansion then cooling over time leads to more electrical resistance and the possibility of corrosion from loosening up and allowing moisture in. Corrosion is an insulator.

Plastic or ceramic fuses with aluminum filaments are also unsatisfactory from a galvanic corrosion perspective. The aluminum filaments and the brass in the fuse block do not get along. They will corrode and overheat if exposed to any moisture. Copper fuses are closer chemically to the brass and get along better. Usually the corrosion is hidden at the brass/aluminum interface until there is a problem. Aluminum fuse filaments are also soft and the ends can distort over time and cause resistance or failure.

The heat cycles from all these issues can also loosen the crimp screws over time and the risk of a wire popping out or getting so hot it burns the insulation is real.

Note that all the wire ends have been 'tinned' with solder at the factory to make the end strands one piece.

If the wire has ever been cut back to expose new conductor, or mauled by an accessory installation, insure that it is re-soldered with good-old lead/tin solder. Do not use Home Depot junk solder. You'll see where each crimp screw has a point and that pins the wire's end within the post and keeps it from escaping. The screw digs down into the soft lead solder and creates a lock. Without solder the strands will separate and there is little to keep them in the post when the screw is tightened. Loose strands that escape the screw are also more subject to power robbing corrosion because of capillary action drawing in corrosive moisture.

Attention to detail here is important to insure there is no electrical resistance and its heat which causes movement which causes looseness and on and on.

I use a tiny amount of grease on these fuse ends and on the brass where they pop in. And I rock them in the fuse holder before the Spring driving season to see they are all tight. They should all feel similar. The spring side can be carefully bent- just don't break them away from the brittle block.

Remember the fuses pop into their own little hole on the post and not the hole where the wire attaches to the posts-

Keep ahead of looseness and corrosion and you'll be as good as new.