Triumphrat

dogtired · 02-19-2010, 10:59 AM

A picture is worth a thousand words.

High seat model.
Note where the frame is welded practically right on top of the oil filler hole, also note the distance between the air box and the seat, also note that the seat lower edge is on the same height level as the tank lower edge, also note the seat looks more "horizontal" than a low seat model, which seemed to be lower at the front than the back.

Low seat model.
Note where the rear frame is welded in relation to the oil filler hole, some inch and a half lower than in the pic above, note the seat seems to sit nearly right on top of the air box, the seat is at a visibly lower level than the tank and seems to slope "downhill" towards the tank

GrandPaulZ · 02-19-2010, 01:52 PM

Or in this case, two pictures are worth several thousand words!

Thanx for posting.

Webby · 02-19-2010, 02:45 PM

Nice one dog

Here's a question do you or anyone know of anyone who has converted high seat model to a low seat model?
I'm not planning on doing it myself (I'm too lazy) but just curious.

Webby

dogtired · 02-21-2010, 08:29 PM

If you ever get the bent to convert one Webby, Scott posted these excellent mech drawings of the frames, thought I should post them here.

Quote:

Originally Posted by HerronScott

Here are frame diagrams of the high seat frame and the low seat frame:

These show the differences pretty clearly. The plunger-style seat latch would seem to be an easy way to tell which you have. Looks like the hinge mount points are closer together on the low seat frame as well.

Scott

Excellent find.

Webby · 02-21-2010, 08:34 PM

Thanks dog,
As I said in my last post, I'm too lazy to bother!
Just, as the lower seat models seem to appeal to a lot more people and (IMO) look better I'm surprised no one has ever tried to convert a high seat model to a low seat, If you've got an angle grinder and a welder it can't be that difficult!
Thanks for posting the diagrams, they are also in the 72 workshop manual.

Webby

scubaguy10 · 04-16-2010, 02:33 PM

There are other variations. Mine is a 72, built about 50 serial numbers before the frame change shown above was implemented. While it has the high frame and the seat hindges on the right, the seat pan itself seems to be wrapped more tightly around the frame rails, and the seat cushion is thinner.

As a result, the bottom of the seat is below the bottom of the tank, closer to the side panels. It looks more like the second example above than the first. With the somewhat thinner cushion, I measure the seat height at 32".

DAVE M · 04-17-2010, 10:04 AM

I wonder if that was a factory attempt? Or a PO's choice to chop the seat?

I have a 79 but bought a stepped seat that drops me by an inch or two as I only have little legs

scubaguy10 · 04-17-2010, 11:10 AM

No, I am pretty sure that my seat is stock. It was an interium attempt to lower the seat height and make the bikes look more like the pre OIF machines. The 71s look a little odd, but I think the 72s look fine to my eyes.

TDodge7 · 02-26-2011, 12:17 PM

I'd just like to add for anyone building a bike from parts that the high frame and low frame rear fenders and grab rails are the same dimensions , but the low frame grab rail has a different reflector mounting point . Also the low frame fender has indents for the battery box and ignition switch which the high frame fender doesn't, plus a few different holes drilled under the seat.

jimmy bush · 02-26-2011, 02:36 PM

According to JR Nelson's Bonnie developement & history book. The 71 & early 72 used 83-3566 fenders, late 72 used 83-4595. The 72 parts book I have access to only lists the 83-3566 #. He also gives two part numbers for the 72 frames: 83-4283 for the early and 83-4578 for later. Again, the parts book only list the early. The frame number given for 71 is 83-2089 so it must be different than the early 72 in some way.