Tech Tip: Triumph Seat Pan Safety Strap Modification

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" 

Vintage Triumph 3TA Advertisement

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 


Triumph Seat Pan Measurements

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"


Caliper Measuring

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)

Stock removal 

Milling Flat Stock

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 

Radius The Corners

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 


Bending tab

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) 


Brazed Bracket On Seat

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 

Pan complete 

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 


Thanks for reading 

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Ride safe! 


  • Classic British Spares

    @Kickstart – thanks for reading! Blog has been updated (1 1/4")

  • KickStart

    I enjoy your ongoing tech tips. The latest about seat strap brackets is interesting. I found a missing dimension in the following line: “The height I measured was approx () which is important”. Was the number excluded for a reason or did you just forget it? Since most of us don’t have spare seat pans, would you please share it with us?
    Thanks for tips.

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