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I just got done installing a top trunk on my 2003 400. Like normal, a 1 hour project took about 5 because I got sidetracked etc. No big rush as it has been raining here in W MI the last few days. Originally I had bought a trunk mount from GIVI because it was on sale. Greed is the downfall of mankind my dad used to tell me.
This fantastic buy right from GIVI was only $25.00/ Well in my greed I did not read that it was for the 400S pre 2007.:frown
So do you now how hard it is to kick yourself in the rear when you are 77. It hurts ALL OVER. :crying
I kept looking and found a do it yourself trunk-mount I believe here on the forum. I read it THOROUGHLY and then said I can do that. The site where it is now is http://www.instructables.com/id/DIY-Trunk-mount-for-2005-suzuki-burgman-400/.
Whoever did it put in some great pictures and really everything was fine, except for the 2 holes I had to drill for the new in the little black plastic inspection plate above and between the tail lights for the new bolts to go through.
I used a after market trunk top mount that I had on my Helix.
It is done, it is solid.
The only thing I added was a couple of covers to cover the 1/2 inbolt hex nead. After much consideraration and searching through boxes of treasures in my garage I came up with 2 3/4 in pvc pipe caps. I thought I'd have to glue them on but the plate on the mount holds them solidly in place. They were sort of pvc color dirty ivory and I thought I'd paint them. Well my flat black spray can of paint had given up the ghost, if you know what I mean. I don't know why the price was only $2.50, maybe it was old? so I found a felt tip pen and painted them. They did not turn out too bad. Considering who I was doing it for! LOL
No pictures yet I can't seem to multitask anymore.
All of you folks Have MERRY CHRISTmas, Happy Hanukkah to You All.:angel4::angel4:
 

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I'm really looking forward to the pictures when you get a chance!
 
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I know this is a old post, but does anyone know how sturdy this way of mounting is? 2 x 1/2” bolts through plastic seems a bit flimsy, what say you?
 

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Well I wouldn't be putting anything in the top box that's for sure. lol.
I think I'd rather do it like this.
A topbox bouncing down the road into an oncoming car is not something I want to be involved in.
 

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Were you able to pass bolts thru the metal frame ....I’m seeing you didn’t remove the pillion backrest ? The box is way past the rear axel ? You’ll not want to over load that box as is it could create a cantilever force raising your front tire enough to creat the dreaded Tank Slapper .

I see you have two threads going...I think it’s an ingenious mounting but the weight will not be anywhere near over the rear axel.... Caution !
 

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Well, I am 300 pounds so I won’t be too worried about it lifting my front tire lol. Also, yes, it is mounted through the metal frame of the backrest. Check out the link I added as to see how it is mounted. Only thing I’m concerned about is that taller trucks and semis may not see my taillights as well so I am adding lights to the case. I don’t plan on putting a huge amount of weight in it, but it could hold quite a lot.
 

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Cool...just remember it the front ever feels lite and you get a bit of wobble hunker down over the handlebars until it passes.
 

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Nice job.
Regarding weight and tank slappers:

As you say, isaksdaddy, raising of the front wheel isn’t going to be very great.
I’d look carefully at the opposite as you unload the rear during breaking or decelerate at speed.

The affect of a top box on weave/wobble is that it creates a long pendulum with a weight at the end that will be excited at a particular frequency (related to the harmonic frequencies of distance to the steering head and wheels, damping ability of the tyres etc).

With smaller wheels and a long frame its easy to hit those harmonic frequencies in 3-8 hz range

You are right to keep the weight down but keep an eye out for signs of weave, particularly when braking.
 

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Honestly, the top box mounted like this is only a few inches further back than it being mounted the typical fashion.
 

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Honestly, the top box mounted like this is only a few inches further back than it being mounted the typical fashion.
Great your bike looks really nice, when I posted I didn’t know you had all the weight between the axels 😀. I was just trying to save you a butt pucker moment or worse.
Bluebottle’s post had me scratching my head until I found more info. He and I are always swapping theory’s back and forth. Reread his post just to be aware of those unseen forces.
 

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I don’t want to spoil your thread. I can post details in a different thread, but -

A few inches change is enough
Daris’ links are about riding v wobbles, I’m talking more of the designing engineering design/results. I work in vehicle dynamics, I’m not basing this on google and guesses.


Everything has a resonant put frequency related to weight and size, any mathematically related frequency will excite the object to oscillate at its resonant one, slightly off and it won’t.

eg an unbalanced tyre is only noticeable at a certain road speed - that speed is where the wheel turns to match to match the resonant frequency of the suspension.
Change the suspension or wheel size and the speed it appears at will change.

Importantly, a 1/2 inch change will change the frequency (think of a guitar string or ruler on the edge of a desk)

Oscillations are designed out of bikes and aircraft during development and track testing - by changing distances and damping, tyre construction and that type of thing. Changes can be small because you are only trying to make the frequency shift from the critical value.
(like the singer misses the note and the glass won’t break no matter how loud they are).

An empty top box can also put forces into the bike at high speed because of aerodynamic factors.

Manufacturer approved topboxes/mounts will have been tested, but even those will have a very low approved weight capacity, it isn’t possible to remove all vibrations - a bike is always two sticks with a hinge between.

I don’t want to detract from what you have done, just saying be aware of the possibility and watch for early signs until you are happy there are no issues :)
 

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I meant to post this here for the "pendulum" argument, but posted it on a new thread instead. Sorry.

Mine was mounted that way, although my support was bolted also on the back (there was two holes on the plastic and two big bolts and about 8cm spacers). It was very "rigid" and nothing were wobbling. I don't know if it was a custom made support or a commercial one (the previous owner worked in an automation machinery factory so he could have been able to build "Pro" looking support like that).
90873


I'm 126kg so rising the front was not an issue, but the handling difference with or without the top case was noticeable.
Rising the hands from the handlebar resulted in "tankslapper" movement, although just putting the hands on it was enough to stop it (and not feeling it on the arms).
Anyway, i never had a problem having it full of stuffs.


I wanted to do the same on the 650 (keeping backrest and topcase) but the backrest is much more "fatty" and the case would have gone too far on the rear.
 
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I’m using the same method, just with 1/2” bolts instead of the GIVI rack. My top case is no further back than what is shown in this video. Already been on a few test rides and nothing feels different. I’ve put about 20 pounds in it and tested again, still no difference. This was at multiple speeds on city roads and freeway.
 
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