Tech Tip: Triumph Seat Pan Safety Strap Modification
Over the weekend I finally found some time to finish up a project that I have been itching to complete
This modification is basically replicating the factory seat strap tabs that where fitted to "west coast models from the Triumph factory to meet safety regulations here in the USA
The factory seat pan that was fitted to my 1962 Triumph 3TA did not feature the saftey strap tabs on the pan as the bike was sold in England and later imported to the US
Today I will cover the work that I performed to replicate the factory seat pan tabs using an original seat as a template that does have the original tabs..
Lets dive in...
Seat pan & strap "history"
Some of you may have seen factory literature and images that might show a Triumph twin with a passenger seat strap on the seat, however, not all seats came that way from the factory destined to the US
In fact, many pans do not have the tabs, while others do
The seat strap appears to be used on models that where fitted with the "grey top" seat and the later black "ribbed" seats
Despite the year and seat pan changes, all straps are the interchangeable
There is some grey area around this topic, however I am not a "restorer"; I simply like the look of the seat straps and wanted one on my 3TA
The original Triumph advert image above shows exactly what I am referring too..
The modification process
I was able to acquire an original seat pan that dates from 1960-1966 in which I used for reference
The first steps I took on the "new" original pan was to measure from front to back to "eye ball" the center of the seat strap brackets which was right under 13"
Once I found the center I documented and recorded the specs on the brackets
I found that the bracket is approx 1" wide, .087" thick and the length was not a big deal as it could be cut to fit
The height I measured was approx 1 1/4" which is important
The self-tapping screw appeared to be a 5/32" screw with an odd 18 thread pitch (very coarse)
Once I had all my specs recorded I selected my material to use
I decided to go with a nominal size steel flat stock that was 1.5" wide with a thickness of 3/32" which was close to factory that I purchased from McMaster Carr
I cut each strip approx 3/8" longer than factory to give me some "wiggle room"
I used my mill to remove all ecsess matieral from each flat stock
Once I had both brackets made I added a radius one end to get the replicate the original design
From there, I transferred each mounting hole from the original vbrackets to the new brackets using a center punch
Once I found the proper hole location I mounting each strap into the kurt vise and began to bore each hole using a 1/8" drill bit
Now the time came to bend each bracket
Since my Kurt vise has some really strong holding power, I decided to bend each bracket in the vice on the mill
The thickness of the steel is only 3/32" which means I could bend the steel using a brass mallet rather easily
Once each bracket was bent to the proper angle (90 degree)
I decided to braze the brackets instead of welding them due to the pan being rather thin
I also noticed under the paint on the original pan that the factory also brazed each brackets in place
Once each bracket was brazed, I tested each piece after to ensure that we had a strong bond in which we did
Now that the pan is complete I do have some additional work to do, however, it is almost ready for painting
I will be using a new seat cover, foam and strap provided by RK Leighton of the UK
To ensure that this pan fits correctly I will have to install the bath tub on the frame to verify that we will not have any clearance or rubbing issues
As of now, I will consider this modification complete
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