buddy seat conversion

[Waltr]

I know this is does not qualify as period correct but I want to add a buddy seat to my 1983 FLH-80. When I purchased this bike I was unaware that changes were made and only frame mount seats were used during this model year.
My "seat post" hole in the frame does not have the cap to receive the threaded portion of the seat post but that is only the matter of welding a drilled cap in the bottom.
My question is concerns the diameter of the tube and what size it needs to be to accept the seat bushing.
My frame has been what looks to be pretty heavy coat of paint or powder/coat from the factory and I am sure the thickness will show up in measurements. That said at the top of the seat down-tube I get 28.25 mm or around 1.111 inch. I am using a digital caliper and do not have a bore gauge.
I was considering using a brake hone to open up the tube to accept a post bushing but do not know how far off I am from making it work. if anyone out the could give me inside diameter of the frame tube it would be helpful.

Walt

[Rubone]

I believe the easiest way to do it is using a 45 seat post which is the smaller diameter top section which will work in that small diameter top hole. All springs are the same so the modern spring kits fit it.

[Waltr]

Thanks for your reply.
Do you or anybody else have the outside diameter of bushing for the 45 post.

[Architect]

I could be wrong, but I believe the latest version of the Buddy Seat, then known as a Comfort Flex with he "bear trap" gizmo below, does not utilize the seat post. The early ones do, but the later version before they went frame mounted, I am pretty sure, does not use the post. They are all over the Bay, early to late easily spotted by the front mount tab to the seat post, either it is there or it is not. Good luck, hope this helps.

[Waltr]

I was able to get the outside diameter of the thin wall version of the bushing used in the later seat posts. Colony makes a replacement and there part number is #3082-7. The outside diameter of the replacement bushing is 1.253 inches. it is listed for years 1958-1984. It seems a little honing should be able to make it work. The guy at Colony said the H-D frame paint was pretty thick.
Arcitect,
I had a Comfort Flex seat on a 1980 and 1981 FLT Tour Glide and loved them. It seems they were not that popular though. I am going to use a Deluxe Twin Rail King Caddy on the back and the Comfort Flex may not work.
T looks like I will have to hone away around 12 thou to get a good interference fit. I am not sure how much of that will be paint.

[LUVMYSHOVELS]

I did thi s conversion on my 83 flh about 8 yrs. ago. I don't recall what size bushing I used or which seat post I used. I do remember welding a washer on the bottom of the down
tube for the seat post. I got a seat post and a t-bar from a friend and a couple of parts to attach the springs. I ride with the springs down or the seat hits fender sometimes. I lucked out at a swapmeet and a nearly new white buddy seat complete with rail and back rest for $125.00. It is the best smooth riding bike I own. Now if Ican figure out how to put one on my 2004 Road King Imight actually ride it. Which I could have been more help.

[Waltr]

Thanks,
Good to know it is possible