ST1100 Back rest measurements????

I have a 91 ST1100 and right now in shop but am wanting to do some farkle and need someone that can give me some quick help, I know I could wait till I get bike back but would appriciate some help... What are the measurements on the distance between the bolts that hold the backrest on??? I am wanting to put on a rack but don't know the distance between the bolts to mount supports for the rack, I am going to have to get holes drilled for bolts to go through and need to know if someone can tell me how far apart I need to drill the holes....

This is what I measured on my 2001 ST1100...



I'd say measurements were ?.005". If you use this, please report back on how it worked.

Thanks,
Paul

The bolt's shank that fit the threaded frame holes measure .309"dia. Clearence hole should be, at least 5/16" dia

the_gr8t_waldo said:

The bolt's shank that fit the threaded frame holes measure .309"dia. Clearence hole should be, at least 5/16" dia

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Good catch. When I made that drawing, I just sized the holes for visual reference. I then drilled my part as needed. I'll verify screw size (8mm I believe) and update the drawing.

just for grins, I measured my own and the holes are slightly different lay out- so with that in mind make the plate and have a round file in hand for final fitting.......... a few years ago I made a plate to act as a mount on which to strap on more luggage. I had to make a set of standoffs to avoid compressing the rubber/vinyl that make the hand grips. the ome bolts are fillister head and screw down so that the strain is transferred to the steel that's cast into the handle ( and on to the bikes frame)., and not on the rubber part of the hand grips ( I can picture, where in a year or so the vinyl would start to split from this compression). And, of course you'll also need new longer bolts. I am interested in seeing a pic of the finished product.

the_gr8t_waldo said:

just for grins, I measured my own and the holes are slightly different lay out- so with that in mind make the plate and have a round file in hand for finale fitting.

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Which dims? How different were they?

not by much, that's why I mentioned "final fitting". my bike as been rearended a few years ago....I doubt if this has any bearing on measurements, but wanted to fully disclose..... I attribute the difference to the manufacturer. These things are, after all, welded assemblies. working around the compass, I got north 7.437", east 3.336", south 6.5", and west 3.272"

Yes, 8mm bolts, and you'll have to make stand-off spacers to keep your rack off the passenger handles. I made some from aluminum rod stock. Thick-walled stainless steel tube stock would work well.

N.B. If the four upper passenger grab handle bolts have never been removed they could very well be frozen. BTDT and had to drill out the broken bolt and chase the threads with a tap. The bolts fasten to nuts welded to the bottom of the Center Plate. They're open and accessible from the under-seat compartment to shoot some penetrant. FWIW

John
via iPhone 4S

So from what I am reading from the front bolt to the back bolt is about 3 1/4" ???

ryterafan said:

So from what I am reading from the front bolt to the back bolt is about 3 1/4" ???

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3.281 center to center, 3.243 along the y-axis. I suggest double checking yours... might be slightly different since these are just welded tubular frames. Put slots in your plate if possible or be ready to drill out 1 or more holes to get all 4 to fit.

I am looking at mounting this under the back rest mount and then put a rack on these ..
.

I'm not sure what you mean by "back rest"

sets over the back of the seat so passenger can lean against....

Aha. The Hondaline accessory backrest has the standoff collars built in. I have one. You're not going to be able to fit anything between (under) it and the passenger grab rails. Take a good look when you get the bike back. I know some folks have jury rigged racks with the Honda backrest but don't have anything in my archives, sorry. Hopefully somebody will chime in with some info. Might try ST-Riders.net and my-mc-phoenix.com.

John
via iPhone 4S

I was totally unaware that Honda has such a farkel

the_gr8t_waldo said:

I was totally unaware that Honda has such a farkel

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had...

P/N 08F75-MAJ-800, backrest ST1100...

Had one on my bike when I bought it. Sold it to Don aka freestyle. If anyone is looking for ST11 parts, he would be a good place to start.

This is the final outcome.... Less then $20....

John OoSTerhuis said:

Aha. The Hondaline accessory backrest has the standoff collars built in. I have one. You're not going to be able to fit anything between (under) it and the passenger grab rails. Take a good look when you get the bike back. I know some folks have jury rigged racks with the Honda backrest but don't have anything in my archives, sorry. Hopefully somebody will chime in with some info. Might try ST-Riders.net and my-mc-phoenix.com.

John
via iPhone 4S

Click to expand...

For your archive, if it is suitable.

I made this very simple rack many years ago. Had a steel fabricator cut me the shape out of 1/4" cold rolled steel, after which I drilled the holes, filed the edges and had it powder coated. Needed to buy some longer bolts too. Recently bought the Kuryakin bag and it sits very nicely on there. As to cost, I have no idea. It was too long ago to remember.