early tail light (stop and park light) bulb part number question

Hi everyone,

I hope your all having a great day
I'm chasing down electric problems as I'm getting close on this restoration
its an all new harness through out... so trying to problem solve a couple of things

so I don't have a rear brake light or park light
pulled the bulb and it looks good... but must have internally broken the connection to ground at the base
because it does not show the continuity on either filament

this is a dual filament bulb.
when I go to the part sites, they show a part number for sale (63 217 160 790)
that bulb is a single filament and is a match for my turn signal bulbs.

my bike is the early "no fuse" harness and I'm betting the early bikes might have been different from the later?
my bike is a March build date, 1971 R75/5

does anyone know the correct part number for the dual filament bulb in this application?
sorry I didn't find it on the diagrams, and my bulb is old and corroded enough that I can't read any numbers off of it.

I'll attach the fiche diagram... which even shows a dual filament in this application

brant

The single element bulb should be the #7506 (or one of its variations, long life etc.) at your local autoparts store. It may also show up as a P21W but I thing that is seldom used. The base is probably the smaller Ba15s. Take your old bulb with you. Hope this helps.

The wiring diagrams seems to show three wires to the brake light, one ground and two for power. Doesn't that suggest two elements, one for running light and one for brake light?

kurt,

thats how mine is wired also
one wire for the park side of the bulb
and one wire for the tail lite side of the bulb
and of course grounded at the base

for certain a 2 filament bulb

brant

MAXBMW shows a single element bulb for the tail light, maybe it's wrong?

Are you sure you have the right part number? I looked at RealOEM and it doesn't show a bulb part number for a '71...the item is grayed out. When I go to Max BMW, they show part 07 11 9 905 336 for all R75/5. Still looks like a single element bulb, though. But they do list a "long life bulb" 63 21 7 160 790 as 12V P21W BA 15s. Single filament. The images that Max has of these two bulbs are very different.

Yes, the drawing shows a dual element but the number 12 on the parts list shows a single element. They also have this note on the tailight housing "It fits many airheads from 1979-1995, but no older models. Use 63216926920 brake light bulb and 07119905336 taillight bulb." Somewhat confusing.

I don't know what the part number is.
I noticed that the 63 217 160 790 part number was listed for item #12 and is the same single filament bulb listed for the turn signals
I also saw the comment on the fiche in Max website with the alternative listing part number for older bikes....

the problem is that all of the part numbers mentioned in this thread are all single filament bulbs... and none will work the same as the original dual filament bulb and wiring on my bike.
I don't think the electrode on my tail light will reach a centered filament style bulb.... I guess if it did, I could choose between having a tail light or a park light... but I don't think I will get either because the electrode will not reach.


I guess I'll go to the auto store and start looking for a dual filament bulb of this size.....since there is obviously a mistake on the fiche, and both Max and Bob both sell a single filament bulb, when I need a dual filament one.

Kurt... does the /2 tail light look similar to the early /5 ? maybe I'll look into a /2 bulb now.....

brant

The tail light bulb in my /7 is dual element...part number is 07119905511. But it doesn't cross reference over to a /5. /2 systems are 6v and I'm pretty sure my R69S doesn't have a running light, just the brake light so just a single filament bulb. So maybe the diagrams are wrong...the early /5s only had brake light. I'm guessing you have inspected the wiring to your brake light and confirmed things. Can you turn the ignition on...no start...and measure voltages at the various contacts back there? Step on the brake and see which contacts get 12v?

20774 said:

The tail light bulb in my /7 is dual element...part number is 07119905511. But it doesn't cross reference over to a /5. /2 systems are 6v and I'm pretty sure my R69S doesn't have a running light, just the brake light so just a single filament bulb. So maybe the diagrams are wrong...the early /5s only had brake light. I'm guessing you have inspected the wiring to your brake light and confirmed things. Can you turn the ignition on...no start...and measure voltages at the various contacts back there? Step on the brake and see which contacts get 12v?

Click to expand...

ahhh... 6 volt... yep that won't work...
I will test the wiring tonight.
I just replaced the whole main harness and it looks corrected correctly according to the diagrams
I was going to test it for voltage last night and then put the ohm meter onto the bulb and found it was actually bad.
so gave up on testing the wiring and started looking for a bulb

but tonight I'll verify the voltage at the wiring.

I do have the battery in...
all of the turnsignals etc working... the front park light working correctly

but nothing on the tail light or brake light
which led to me checking the bulb first last night and then hitting pause.

brant

Mine has a dual element bulb

I have an early R 75/5 and it has a dual element bulb. You need that type of bulb in order to have a tail light and brake light with one light bulb. Back then that's the only way to get the different intensities in the light. Sometimes parts diagrams can be wrong and confusing especially when they use the same one for multiple years and configurations.

Thank you again everyone

last night I took a test light and verified that the wiring was correct for the rear park lamp and also the rear brake lamp...
both working as they should...

my bulb has the offset dual pins of an 1157 style of bulb
so I decided to go through my large crate of used automotive bulbs from previous cars

and found one marked 12V 21/5

then started looking at my housing (pictured below)
and it is stamped in the hella housing with the same 21/5
put the bulb in and it works perfectly...

also... Kurt... I put in an order this morning for some spare turn and instrument bulbs.
could not tell for certain if your /7 dual element bulb had offset side pins, or side pins of matching height to each other...
but ordered one anyways... as I think that is the one...

thanks everyone
I would kinda think someone put a /7 tailight guts into my /5
but do not... because the brand new frame electrical harness also has the 2 wires with the soldered tips and no terminal to fit into this housing with the early spring load connectors
so given that the housing matches the harness... this has to be a stock housing... just not common apparently... definitely this bike and wiring harness take the dual element bulb

thanks again everyone.
fixed now!
brant

Just

I just got in from the shop looking at the bulbs I have on hand and was going to give you the same number bulb you now have on hand.

Look, for everyone's sake bulbs don't have to be ordered from BMW by their part number. A good auto parts shop can give you a match in 95% of the times far cheaper.

Better yet for tail lights is to install the Motorrad Electrik replacement LED unit. It replaces the reflector, sockets and bulbs with a one piece unit of rows of LED lights. In your case, the biggest problem would be crimping terminals onto the ends of your wires to fit the new unit.

LOL I should say perhaps sending an Email to Rick at ME, making sure the unit will fit your housing would be the first thing to do. The LED light unit is the way to go.

I actually upgraded my one bulb tail light to a two bulb unit from a newer bike then scrapped the reflector bulbs and sockets for the ME LED unit. Even better rear lighting.


I don't know what you have for instrument lights, if you have a chance check out Katdash web site. Kat dash is the way to go, since I have installed two of the units in my two bikes, I have not had a housing aprart in three years to change a bulb or fuss with the BMW nonsense bulb sockets.

I know, this is a lot of gab on my part and a big ego play but really, I have seen the real advantages of LED systems in my two bikes. Little guys like Kat and others making the almost perfect bikes closer to perfection. St.

The dual filament bulb is termed P21/5W.

A single filament brake light bulb is termed P21W.

An orange turn signal bulb (which Airheads don't use) is termed PY21W.

About anything with a 'mericun bulb number will be lesser quality.

American bulbs

Yes, those German bulbs last forever. Us Americans don't know how to make things as well. So don't waste your money on the cheap American bulbs or goodness even cheaper Chinese ones. St.

lkchris said:

About anything with a 'mericun bulb number will be lesser quality.

Click to expand...

STEVENRANKIN said:

Yes, those German bulbs last forever. Us Americans don't know how to make things as well. So don't waste your money on the cheap American bulbs or goodness even cheaper Chinese ones. St.

Click to expand...

Do you have to to your Germany and watch them being made at the German factory to get these bulbs you guys think are superior?

These Osram bulbs, H-7, made in Germany, are the shortest lasting bulbs I have ever used/replaced/gone through.


Happen to have that N/G bulb after replacing it AGAIN on the F800GS.
OM

Me

I am being sarcastic, not the first time I have been so. BMW parts are not all they are cracked up to be sometimes for the price paid. I haven't believed BMW to be the best for a long time. They made a good product back in the day up until 84, worth the money then not so much these day, such a good product I continue to use it and improve upon it still.

Besides, bulbs are old technology, as I mentioned in my post a far superior LED units can be purchased now thanks to little companies making an almost perfect bike nearer perfection.

With minor labor, no rewiring and a few extra bucks, the tail light can be converted to LED and so far, I have a lot of miles and years on the unit I have in my bikes without a blown bulb, corrosion, and far better light output.

Anyway, this thread has gone off on another track. I don't know if Brant had any luck on solving his problem or not. I hope so. St.

He solved it at post # 12 ... As with my '71 and early '73 /5s, the bulb is an 1157.

LEDs are cool, but so many of them do not "fill" the lens; I've found that the SuperBrightLEDs p/n 1157-CW30-CBT is pretty good. But like Steve says, the newer multiple-LED replacement assemblies (multiple LEDs) are even better.

STEVENRANKIN said:

I am being sarcastic, not the first time I have been so. BMW parts are not all they are cracked up to be sometimes for the price paid. I haven't believed BMW to be the best for a long time. They made a good product back in the day up until 84, worth the money then not so much these day, such a good product I continue to use it and improve upon it still.

Besides, bulbs are old technology, as I mentioned in my post a far superior LED units can be purchased now thanks to little companies making an almost perfect bike nearer perfection.

With minor labor, no rewiring and a few extra bucks, the tail light can be converted to LED and so far, I have a lot of miles and years on the unit I have in my bikes without a blown bulb, corrosion, and far better light output.

Anyway, this thread has gone off on another track. I don't know if Brant had any luck on solving his problem or not. I hope so. St.

Click to expand...

Steve,

I found (probably american made... at least it doesn't state china on it) one in my parts hording stash...
and also ordered one from Max for a later model bike with the dual filament
when it arrives that way I'll have a spare and should probably switch them out since the one I found (working) is a used one.
brant

Next time, check into a 2057LL from any auto parts store ... slightly brighter (and therefore slightly more current), and the LL means long life (as compared to an el cheapo).