Differences between 1937-39 and 1940 tanks.

All flathead topics
Post Reply
flatheadmatt
Posts: 25
Joined: Sat Mar 03, 2018 11:01 pm
Bikes: 37u
Has thanked: 7 times
Been thanked: 1 time

Differences between 1937-39 and 1940 tanks.

#1

Post by flatheadmatt » Sun Mar 17, 2019 2:15 am

I found a set of "37-39" tanks and was wondering how to tell if they are actually from those years and not later tanks. On the left tank i stuck my finger in and felt around. It almost feels like a round remnant from the reserve rod in front of the gastank is present although from the outside nothing they show no evidence and appear to be earlier tanks. Any guidance appreciated.



RUBONE
Moderator
Posts: 5347
Joined: Sat Nov 15, 2008 4:09 am
Bikes: Multiple H-D, Ducati, BMW, Triumph, BSA,...
Has thanked: 36 times
Been thanked: 576 times

Re: Differences between 1937-39 and 1940 tanks.

#2

Post by RUBONE » Sun Mar 17, 2019 4:18 am

Matt, are you talking Big Twin or 45 tanks?

1950Panhead
Posts: 1756
Joined: Wed Jul 07, 2010 4:28 am
Bikes: 1950Panhead
Location: USA
Been thanked: 148 times

Re: Differences between 1937-39 and 1940 tanks.

#3

Post by 1950Panhead » Sun Mar 17, 2019 1:16 pm

I found a set of "37-39" tanks and was wondering how to tell if they are actually from those years and not later tanks. On the left tank i stuck my finger in and felt around. It almost feels like a round remnant from the reserve rod in front of the gastank is present although from the outside nothing they show no evidence and appear to be earlier tanks. Any guidance appreciated.
The 37 to 39 tanks do not use the fuel shot off rod and the lower fitting is a different size.
It is possible to convert later tanks to early tanks by pulling the fuel rod indent up with a slide hammer and brazing shut.

flatheadmatt
Posts: 25
Joined: Sat Mar 03, 2018 11:01 pm
Bikes: 37u
Has thanked: 7 times
Been thanked: 1 time

Re: Differences between 1937-39 and 1940 tanks.

#4

Post by flatheadmatt » Sun Mar 17, 2019 4:49 pm

RUBONE wrote:
Sun Mar 17, 2019 4:18 am
Matt, are you talking Big Twin or 45 tanks?
Big twin tanks.

RUBONE
Moderator
Posts: 5347
Joined: Sat Nov 15, 2008 4:09 am
Bikes: Multiple H-D, Ducati, BMW, Triumph, BSA,...
Has thanked: 36 times
Been thanked: 576 times

Re: Differences between 1937-39 and 1940 tanks.

#5

Post by RUBONE » Sun Mar 17, 2019 6:59 pm

The early BT flathead tanks ('37-'38) had flat backs without the ribs added to the left tank in '39. The right tank has a female rather than male fitting on it, the left tank just the pipe taper thread for the petcock without a sealing surface around it like the '40 up tank has. Any pictures?

flatheadmatt
Posts: 25
Joined: Sat Mar 03, 2018 11:01 pm
Bikes: 37u
Has thanked: 7 times
Been thanked: 1 time

Re: Differences between 1937-39 and 1940 tanks.

#6

Post by flatheadmatt » Mon Mar 18, 2019 5:42 am

20190316-175532.jpg
20190316-175532.jpg (99.96 KiB) Viewed 76 times
20190316-175512.jpg
20190316-175512.jpg (98.32 KiB) Viewed 76 times
20190316-175453.jpg
20190316-175453.jpg (98.62 KiB) Viewed 76 times

Wish the pics were better but they are all i have.

Post Reply

Return to “Flathead and Servicar”