74 Roadster wire routing

Onder · Jul 8, 2012

1974 Roadster 312xxx. Could some kind soul post a pix or two of the tail lamp area conductor
routing? PO seems to have been in here and taken some liberties. Just how does the cable
bundle proceed from the shock area and esp how does it transition from frame rail to
tail lamp housing? Where do the bullet connectors mate up?
Also, just how does the horn and horn mount attach to the tab on the bottom of battery
tray and rear fender. I realize it is tight back there but seems almost impossible no
matter how I arrange it. 1974 seems to have a bit of MkIII to it at times.
Pix of a stock set up would really assist!

Onder · Jul 8, 2012

Well I see 30 peeps have peeped at this thread no response.
I will say I have searched the list and found DogT mentions that
horn and fender mounting is variable. Looks like it is doable with
extra long bolts all spaced out with copious washers. But one
does wonder how the hell they did it at the factory.
Still hoping for a pix or two of just how the proper routing
is for tail lamp connections.
Oh, and the little spacer that goes under the fender on the
forward loop over the rear frame, just what is that for? My
stock bolt isnt really long enough. Damn spacer cost me over
7 bucks! :-(

cjandme · Jul 8, 2012

Try Old Britts site as they have the diagrams on line. Cj

drones76 · Jul 8, 2012

Give me a few minutes. I took some pics of my '74 314xxx. I will edit this post. I removed my horn and put a $2 Chinese special on the front of the battery box. I cannot help you there.

I have pics from the loom through the frame/grommet, along the right seat rail and around the loop to the light. The bullets connect under the top horizontal light support that connect to the fender. At that point I have mine wrapped in a little electrical tape.

Here is a top down view at the grommet where the tail light wires go through the frame next to the oil tank mount.

Along the right seat rail. That zip tie in the foreground is original.

Going under the tail light support. The bullets are under there. When I first put it on they were exposed and needed to by pulled under a bit for some shelter.

rvich · Jul 8, 2012

I don't have any pics of my stock horn set up, and frankly I don't plan to put it back, but since the pieces are all sitting around the shop I will see if I can get a photo later. As for the stock routing of the wires, they follow the frame loops back to where it goes under the tail light fairing. They are attached with zip ties. Once under the fairing they head straight for the tail light and the connectors are in the space just forward of the light, inside the fairing.

You mention a spacer. As near as I remember, the fender bracket (rear mudguard clip) has what is essentially a hollow bolt that gets the spacer underneath. It is necessary because the screw that holds the fairing on goes deeply enough into that bolt that the extra length is needed. Check out group #27 at Old Britts web site. http://www.oldbritts.com

Onder · Jul 8, 2012

Thanks, it seems Im too fastidious. The cable bundle just weasels its way under. Pretty
non aircraft! Geez,tie wraps! Maybe Ill salve my conscience and use adels.
That spacer thing is still puzzling. Original one long gone. The philips head screw
that hold the fibreglass tail lalmp piece on doesnt protrude. Perhaps not original.
As for the horn, Im warming to the idea of mounting the horn elsewhere or mounting
a smaller horn likewise.
Thanks for the help. All logic flies out the window when trying to figure out the
stock approach!

rvich · Jul 8, 2012

check the Old Britts site and look at the blow up picture of the rear fender, I think the spacer thing will make some sense. There is an internally threaded bolt.

Brooking 850 · Jul 8, 2012

My wiring heads along the inside of the right hand rear loop, goes in under the side of the fibrelass cover of the tail light frame, along the main tail bracket mount, here there is a series of bullet connecters, I tie wrap them in place here(zip tie)then the tail light /stop goup through a grommet through the back of the tail light mount, the indicator wires then go down through a grommet in the frame out to each indicator
Hooe this helps
Regards Mike

rvich · Jul 8, 2012

I just went up to my shop and looked around for horn mounting stuff. I have a number of pieces from my 850 at another location I use for painting (i.e. where I work, and I am not going in there on Sunday!) so I can't cobble up a horn mounting photo very well. And as I have removed the original horn from my 750 I am working from memory here. Somebody should be able to confirm and help out here.

On the leading edge of the rear fender there are two bolts down low that attach the bottom rear of the battery box to the fender. There is an elongated triangular metal braket that goes on the forward side of those two bolts before they go thru the flange on the battery box. That triangular piece points down and stands parallel to the lower edge of the fender by maybe a half inch. There is a single hole in that bracket that recieves the bolt from the horn.

I will gather pieces up for a photo if you still need it and somebody else doesn't come up with one first.

Russ

Guido · Jul 8, 2012

rvich said:
On the leading edge of the rear fender there are two bolts down low that attach the bottom rear of the battery box to the fender. There is an elongated triangular metal braket that goes on the forward side of those two bolts before they go thru the flange on the battery box. That triangular piece points down and stands parallel to the lower edge of the fender by maybe a half inch. There is a single hole in that bracket that recieves the bolt from the horn.

Russ

That's exactly how the horn mounts as I had just replaced mine this year.
The stock horn on mine got tangled in the chain on a ride in the mountains. I was able to pry it away till I got home.
I replaced it with a Fiamm horn I got from an auto wrecker for $2.
It's smaller, fits between the cradle and is soooo loud and deep sounding and say's "Get out of my f#@^%!ng way!". The stock horn is a joke.
You can't even see this horn any way and it hangs in the stock location.

Onder · Jul 9, 2012

Again, thx to all, common sense would seem to kick in here.
Dump that piece of lead and mount a light loud unit for small money.

Snorton74 · Jul 31, 2012

Any experience out there with wiring through the rear hoop?

DogT · Jul 31, 2012

Onder said:
Well I see 30 peeps have peeped at this thread no response.
I will say I have searched the list and found DogT mentions that
horn and fender mounting is variable. (

All bets are off after 1970. I haven't a clue what happened after '70.

Now if you want a picture of the 69-70 rear assembly and wiring I can supply that, but there are no turn indicators.

I like it that way.

dave

stockie2 · Aug 1, 2012

Onder,
Ah the 850 horn, yes that was about the most puzzling part of my restoration, and you pretty well need to completely dismantle the the bike to remove it, ask me how I know. The big old Lucas snail job, cops some vibes down there, and mine came loose on the threaded single bolt that it attaches off the spring mount. I had to re tap the hole, and I finally settled on the horn outlet downward and to the right. It pays to spay some WD40 in there every now and then to stop corrosion inside the horn.
Phillips head screw holding the tail lamp cover on the guard is original.

Cheers Richard

Onder · Aug 1, 2012

DogT: concur heartily with the no indicators. One the back they are
barely acceptable, on the front blasphemy. But life in modern traffic.....

In days of old my '72 horn crapped out same place: threads for the bolt to
bracket. Pretty much have decided to put the horn elsewhere, just cannot
face the eventuality of inevitability.
Thx for the clue on the fibreglass tail light bracket cover screw. The parts drawing
shows a slot head which seems pre 70 rather than 74 era.
One thing puzzles is whether or not the incoming conductors go under the
fibre and over the metal bracket or under it. Over make more sense and using
a 5 pin bullet connector the way to go. The five pin cnx is my idea but Ive
seen pix that show the bundle going either under or over.
Recent pix of Maylar's bike, identical to mine, would be real helpful as he
apparently has owned his since new and it is in wonderful condition. Hats off
to Maylar and perhaps he could post a few illuminating pix in that area?
hint hint

maylar · Aug 6, 2012

Sorry for the late reply...

Here's my '74 rear fender. Pretty much as described above. The luggage rack is home made.

Onder · Aug 6, 2012

Thanks much, looks like I was making a mountain out of a mole hill.
One of the conductors was poorly repaired by PO so that sort of
confused me.

74 Roadster wire routing

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