N15CS oil tank mounting

Joined
Mar 28, 2018
Messages
20
Country flag
 

franko

VIP MEMBER
Joined
Dec 29, 2013
Messages
137
Country flag
This is the one on the chopped N15:

IMG_0536.JPG

I think it was made to fit under the fender. I'm showing it for others who need ideas on what will work in a pinch.
IMG_0537.JPG

IMG_0540.JPG


IMG_0541.JPG
IMG_0542.JPG

Notice, after the arch, one side has a longer leg. This goes on the oil tank side. Ya, I couldn't get the fender to line up, so I had to do a look see.
IMG_0543.JPG
IMG_0544.JPG

IMG_0545.JPG

the graph paper is 1/4 inch grid. I did this is a bit of a rush. I can answer more questions about sizes later, but I thought this would work for a quick answer.
 

Attachments

Joined
Mar 28, 2018
Messages
20
Country flag
This how mine is fixed:


Although I own the bike from new (probably the last hybrid ever produced) it is no longer original.
The rear loop has been reinforced, etc..
I may have changed the position of the oil tank, to bring it more in.
You can see that the crease on the oil tank runs parallel with the frame tube.
This will also depend on the front tank mount:
Do you have a straight strap or a later one with an angle to bring the tank more inwards?
(= better, so that the filler cap won't poke in your leg)
Don't worry too much about originality ( they were all different) but try to mount the oil tank as stressfree as possible.
When you tighten the front mount, you get an idea where the rear mount should land.
P
This is the one on the chopped N15:

View attachment 16244
I think it was made to fit under the fender. I'm showing it for others who need ideas on what will work in a pinch.
View attachment 16245
View attachment 16247

View attachment 16248View attachment 16249
Notice, after the arch, one side has a longer leg. This goes on the oil tank side. Ya, I couldn't get the fender to line up, so I had to do a look see.
View attachment 16251View attachment 16252
View attachment 16253
the graph paper is 1/4 inch grid. I did this is a bit of a rush. I can answer more questions about sizes later, but I thought this would work for a quick answer.
 
Joined
Mar 28, 2018
Messages
20
Country flag
Just another question on a different subject, i’m trying to work out the route for the brake light switch wiring. I have looked at lots of images of N/G15s and can see that the 2 wires tuck under the frame gusset, but can see no detail from there. One cable is the feed and the other is to the lamp, so they must both go up to the top of the frame but I can’t see any images that show them being strapped to the frame anywhere. It’s all close to the chain/swing arm/chain guard down there and plenty of scope for the cable to chafe.
 
Joined
Jan 19, 2012
Messages
1,029
Country flag
Thank you very much, Franco, your effort is much appreciated. I believe the second bridge depicted to be genuine. I will set out to make a 2D drawing. There will be some questions in due course.

The assy and detail photo also shows the spacer (030396, 2 off). It's for 3/8" bolts. Spacer dimension appears to be 7/16 x 9/8 x 1" - please confirm.

Bridge (030394) length appears to be 30x1/4" = 7-1/2" externally and 1" wide. Please confirm. Sheet metal thickness appears to be approx. 1/8" (3.5mm) - please confirm.

Would you please take a reading of the c/c distance between the mudguard mounting holes along the curved surface (use of a tape measure is advised).

While you are at it - do you also have the "J" bracket (031597) at the lower front end of fender? Would you please depict it similar to the above? I would like to make a 2D drawing of this bracket as well.

The non-symmetrical shape of the bridge is a puzzle to me. The rear wheel has no offset and the rim should be central to the bike's vertical plane passing trough the spine tube. The swinging arm looks symmetrical to me. Is the subframe non-symmetrical wrt. the central vertical plane? Any ideas or information is welcome.

Thanks and best regards,
Knut
 
Last edited:

franko

VIP MEMBER
Joined
Dec 29, 2013
Messages
137
Country flag
Here is what I was able to come up with:
IMG_0562.JPG

All on this drawing start on the tool box side, end of the bracket.
1 1/4" to center line of first radius
1 11/16" to center line of second radius
3 15/16" to center line of 5/16" hole
5 19/32" to center line of 3/16" hole I think this hole is to locate the piece on the press for bending
7 1/4" to center line of 5/16" hole
9 5/8" to center line of third radius
10 1/2" to center line of fourth radius
11 3/4" to end of piece
Slotted holes are 7/16" by 9/16" with a 11/64" wide end
the strap is 1" wide and .092" with paint on thick=
The spacer pieces are 7/8" round stock by .770" and .790" with a .390" hole through them. They have marks on both ends from being turned on a lathe.
the radius of the fender is 8" and 5 3/4" across
it is centered in the frame with an 1 1/2" clearance on both sides
IMG_0558.JPG
IMG_0559.JPG
IMG_0560.JPG

I wasn't thinking when I made these measurements from the oil tank side
With all this being said, although the fender shows that the bridge had been in place a long time, I noticed that the short leg side is pulled away from the fender.
IMG_0548.JPG
IMG_0549.JPG

As I was looking for pictures online, I came across a Ebay seller that had the spacer pieces that were chromed for sale.
If I find the ad again I will edit this and post it here.
I have not been able to find pictures of N/G 15 co G12 support bridges yet.
Agent X and Pierodn both have these bikes that they are working on. Maybe they could take a look and see what they have for a support for the fender.
I did not want to disassemble the bike any more than this. I have my Commando torn apart now and don't want to get sidetracked and have a limited amount of room to work. When I get started on the Matchless in earnest again, I will get the pictures and dimensions of the J bracket.
Frank Coleman
Edit: Here is what I think I saw the other night
.

While reveiwing the last two pictures, it looks as if the bend on the toolbox side is not correct. The oil tank side has the bend above the fender edge and the tool box side is below the fender edge.
I will try to play with the drawing later today and see what I can come up with.

Another edit: While looking at ads tonight, I came across this picture.
The example that andrew showed had slots instead of holes for the attachment to the fender. I don't have any measurements for direct comparison, but they look close.
 

Attachments

Last edited:
Joined
Apr 20, 2011
Messages
4,525
Country flag
Here is what I was able to come up with:
View attachment 16373
All on this drawing start on the tool box side, end of the bracket.
1 1/4" to center line of first radius
1 11/16" to center line of second radius
3 15/16" to center line of 5/16" hole
5 19/32" to center line of 3/16" hole I think this hole is to locate the piece on the press for bending
7 1/4" to center line of 5/16" hole
9 5/8" to center line of third radius
10 1/2" to center line of fourth radius
11 3/4" to end of piece
Slotted holes are 7/16" by 9/16" with a 11/64" wide end
the strap is 1" wide and .092" with paint on thick=
The spacer pieces are 7/8" round stock by .770" and .790" with a .390" hole through them. They have marks on both ends from being turned on a lathe.
the radius of the fender is 8" and 5 3/4" across
it is centered in the frame with an 1 1/2" clearance on both sides
View attachment 16375View attachment 16376View attachment 16377
I wasn't thinking when I made these measurements from the oil tank side
With all this being said, although the fender shows that the bridge had been in place a long time, I noticed that the short leg side is pulled away from the fender.
View attachment 16378View attachment 16379
As I was looking for pictures online, I came across a Ebay seller that had the spacer pieces that were chromed for sale.
If I find the ad again I will edit this and post it here.
I have not been able to find pictures of N/G 15 co G12 support bridges yet.
Agent X and Pierodn both have these bikes that they are working on. Maybe they could take a look and see what they have for a support for the fender.
I did not want to disassemble the bike any more than this. I have my Commando torn apart now and don't want to get sidetracked and have a limited amount of room to work. When I get started on the Matchless in earnest again, I will get the pictures and dimensions of the J bracket.
Frank Coleman
Edit: Here is what I think I saw the other night
.

While reveiwing the last two pictures, it looks as if the bend on the toolbox side is not correct. The oil tank side has the bend above the fender edge and the tool box side is below the fender edge.
I will try to play with the drawing later today and see what I can come up with.
Not saying it is but the bracket looks almost the same for the w/line frame on the Norton parts list on the 56 to 59 wideline on this forum, list no 93.
 

franko

VIP MEMBER
Joined
Dec 29, 2013
Messages
137
Country flag
Bernard: keen observation. It's possible that they used an available bridge and made the round stock spacers to suit fitment to the matchless frame.
I would need to look for the part number, then order one just to satisfy my curiosity.
Would you happen to know what the part number is?
Thank you
 
Joined
Apr 20, 2011
Messages
4,525
Country flag
Bernard: keen observation. It's possible that they used an available bridge and made the round stock spacers to suit fitment to the matchless frame.
I would need to look for the part number, then order one just to satisfy my curiosity.
Would you happen to know what the part number is?
Thank you
Soz, no can't see it on website, it's the wrong page. Someone like Russell Motors or others who do 88,99 might have spares book or you could just PM Richard tool.
 
Joined
Mar 28, 2018
Messages
20
Country flag
Having spent some time poring over parts lists, books with original illustrations and internet images, I have come to the following conclusions, and I would appreciate anyone with more knowledge than me to clarify :
I believe the mudguard bridge is only specified for earlier machines ie 1964/65 (although they seemed to change mid 1965, I’m guessing around October production coinciding with engine changes) - I am basing this on the bridge is only listed in the 64/65 parts book, not in the 66 on parts list.
Every image I have seen of a later machine with the seat having the central rear mounting on the mudguard, the seat is higher, and the bridge is not visible, despite clearly seeing the top shocker mounts, there is no bridge attached to them.
My assumption is the bridge is fitted to the earlier machines with the seat that attaches to the 2 side mountings for the rear mudguard loop, this seat is lower and the part where the bridge would be is not visible. I am not sure what the purpose of the bridge is though, one would think it’s to give more support to the mudguard where the seat is attached to it, but then that doesn’t apply to the earlier seat?
Any thoughts....
 
Joined
Mar 28, 2018
Messages
20
Country flag
Forgot to mention, I have an N15 rear mudguard, reportedly from a 1966 model, with the single hole for rear seat fixing, but no holes for mudguard bridge.
 
Joined
Jan 19, 2012
Messages
1,029
Country flag
Having spent some time poring over parts lists, books with original illustrations and internet images, I have come to the following conclusions, and I would appreciate anyone with more knowledge than me to clarify :
<snip>
Andrew,
I have no definite answer either. The 1966-67-68 parts list mentions "support-bridge bolts", this may be a typo as no support bridge (030394) is listed. By "support-bridge bolts" maybe they meant "support-loop bracket bolts". This is likely as there are no bolts listed for the loop elsewhere. Furthermore, I perused pictures of an apparent genuine 1968 G15CS mudguard, and there are no holes for a bridge. So you may be right. However, looking at bike pictures may be misleading. There are very few bikes in as-delivered configuarion left, and ads like "3 steps to victory" may not portray a production bike.

One question needs to be answered: How is the seat load transferred to the subframe? The rear mudguard can't trensfer the 1966-type seat load by itself and will form crack(s) sooner or later.

-Knut
 
Joined
Mar 28, 2018
Messages
20
Country flag
I looked on the Walridge inventory, and the support bridge bolts (012565) listed in the 66 on parts list are 1/2 x 2BA, so maybe they are the rearmost fixings (they are listed directly following the loop on the parts list) - seem a bit small though, and odd that they use BA, but very close to 3/16 cycle so maybe a typo.
 
Joined
Mar 28, 2018
Messages
20
Country flag
Knut, from images I have seen of the underside of the later seat, there are 2 box section brackets that would rest on the cross tube either side of the mudguard clamp. On my frame which I am pretty sure now is an early 65, there are 2 crudely drilled holes (not all the way through) that would correspond to these brackets, I can only guess a PO must have drilled these holes to fit rubbers to support a later seat - I can’t imagine the factory would have drilled holes in this fashion, plus there is no mention of rubbers in parts lists. But still little support for the back of the seat.
 
Joined
Jan 19, 2012
Messages
1,029
Country flag
I looked on the Walridge inventory, and the support bridge bolts (012565) listed in the 66 on parts list are 1/2 x 2BA, so maybe they are the rearmost fixings (they are listed directly following the loop on the parts list) - seem a bit small though, and odd that they use BA, but very close to 3/16 cycle so maybe a typo.
I bet the correct bolt to use is 000070, 1/4 x 9/16 x 26 tpi, same as used on the G15Mk2 front stay to mudguard (single bolt per bracket).
2BA is indeed small and hardly appropriate given the loads from the tail light fairing and number plate - probably ok if loop brackets are for twin bolts each, as on the G15CS and P11(A) front mudguard stays.
NM14481 (1/4 x 3/4 x 26 tpi ) is another option, as used on the P11(A), requires a grommet which may not be a bad idea even if the fender is steel, not aluminum.
1964-65 G15CS used 000070 for the rear fender bridge.

012565 stay to front mudguard fixing is depicted here:

-Knut
 
Joined
Jan 19, 2012
Messages
1,029
Country flag
Knut, from images I have seen of the underside of the later seat, there are 2 box section brackets that would rest on the cross tube either side of the mudguard clamp.
<..> But still little support for the back of the seat.
I agree on the seat pan, as I have a P11 Ranger seat which is basically of similar design.

The G15CS seat pan tab attaches to the mudguard only, which is the sole rear end support for the seat. This is completely inadequate and causes denting and cracking of the mudguard, as depicted in the 1968 G15CS rear fender I have on file. It seems the factory cheated here, maybe because no simple solution is on hand.

The only lasting solution is extending the subframe past the rear shock mounts and shortening the support tube correspondingly. The shock mounts would have to be altered as well, so this would be a substantial redesign. Then a brigde can be fitted above (preferably) or below the mudguard, welded to the extended subframe. The P11A had an arrangement halfway like this (although attaching to the loop - itself quite flexible). The design was poor and didn't stand up to the loads. Matchless roadsters (G15Mk2, G12) had substantiual mudguards capable of supporting a seat, this is not the case with the G15CS/R or the late G80CS.

-Knut
 
Last edited:
Joined
Aug 30, 2006
Messages
362
Country flag
I agree on the seat pan, as I have a P11 Ranger seat which is basically of similar design.

The G15CS seat pan tab attaches to the mudguard only, which is the sole rear end support for the seat. This is completely inadequate and causes denting and cracking of the mudguard, ...

-Knut
It is my experience that it is not the mudguard, but the seat pan that is the weak point.
It will crack and bend before the mudguard will.
I toured extensively with my N15 (two up), and with a reinforced seatpan, the rear fixing point holds up just fine.

3 pics of the same bike with 20 years ( and 100 000km) interval:



 
Top