Harley Davidson Bobber authentic vintage racing upgrade.
you can give your rigid frame Harley Davidson Bobber an authentic vintage racing upgrade using a replica shortened oil tank.
shortened oil tanks were used on 1936 and later Harley Davidson TT racers, flat trackers and hill climbers.
This allowed the transmission to be raised Creating more ground clearance for the transmission and clutch basket.
A Replica black TT Bobber rigid frame oil tank is 1-5/16″ shorter to allow the transmission to be raised 1-5/16″ Creating more ground clearance for the transmission and clutch basket.
Here is a rundown of the modifications you need to make including descriptions of the the parts and hardware needed to make the upgrade.
Remove oil tank, transmission and transmission mounting plate.
Raise oil tank front mounting bracket 1-1/4 inch.
To raise the transmission mount plate use (5) 1-5/16″ spacers 3/8″ inner diameter X 1″ outer diameter and mount using 1-5/16″ longer bolts.
Reinstall transmission and oil tank.
Inner primary front mounting holes will need to modified. moved slightly to compensate for the change in mounting angle.
If you are running a chain guard. the front mounting tab will have to modified to match higher rear mounting tab location on oil tank.
The battery compartment has been shortened in this tank so you will need a shorter battery. below are some batteries that will fit.
H-3-6-volt-battery 
Mini-12-volt-battery-12N5.5A-3B 
12 Volt 6 Amp AGM Battery
To complete your Harley Davidson Bobber an authentic vintage racing upgrade reassemble in reverse order.
This upgrade can be done using the replica shortened TT oil tank with any early style EL or FL transmission 1936-1964.
Shortened horseshoe oil tanks can also be used when retrofitting early model EL and FL with electric start.
product development video of Replica black TT Bobber rigid frame oil tank .