What is the geometry effect of...

[sam000lee]

... putting an 18" wheel on a GS450L and putting a pair of 14" shocks on. I bought the wheel to build this frame up (along with GS500 cylinders + cams and some other stuff) and have a pair of 14" Hagons lying around. Is that too much to lift the rear by and will it compromise stability/handle terribly?

The stock wheel is 16" and the stock shocks are 13" so the rear would be raised a little less than 2".

Here it is with the stock shocks and 18" rear:

 

[80GS850GBob]

Moving the rear of the bike up will change your rake and trail...dropping it will too. Any attitude change, front or rear, will change R&T.
Raising the rear is the same as lowering the front...it will steepen the neck angle. GS oem R&T from the factory is somewhat lax, but you'll want to check your current R&T, after any height re-adjusting, to make sure your in a safe R&T setting.

 

[Gorminrider]

it's sort of the same as letting your stanchions up an inch or so through the triple tree...judging by what I've seen online and tried, around an inch is considered ok but more is trickier.... You'll have to try it and see I guess. You can always go back a step (original tire or wheel) if it's unpleasant.

"Lifting" the rear with shocks lowers the swing arm a bit versus the frame and the original chain will seem to be a bit longer. If you ever expect to hit a big bump, the swing arm will tighten the chain a little... The smaller rear might have swung past the max and then loosened again so a little more chain slack might be wanted ...

But considering the same frame is used on the
E has 18" rear 18" front
T has 17" rear 19" front
L has 16" rear 19" front

you're not far beyond what is considered by Suzuki to be safe enough for their customers but they seemed inclined to lengthen the wheelbase rather than shorten it as you are doing.

 

[sam000lee]

But considering the same frame is used on the
E has 18" rear 18" front
T has 17" rear 19" front
L has 16" rear 19" front

you're not far beyond what is considered by Suzuki to be safe enough for their customers but they seemed inclined to lengthen the wheelbase rather than shorten it as you are doing.

Thanks for the input - for some reason I was under the impression that the T and E frames were the same but the L was a little different. I'm going to remeasure my wheel which I thought was 18" but if it has 19" up front then it will effectively be 19" front and back once I add the longer shocks.

 

[Gorminrider]

I confess I've never had an L but For sure, Looking at your picture you call a 450L , it's the same frame as my T excepting whatever you have per sidecover tabs... L sidecovers are notably different to accomodate the high-stepping seat.

.. the differences in the frames seem to be just in the tabs and things they tacked on to take different tanks and sidecovers and coils too in the E .


I'm also pretty sure the front wheel on yours was originally a 19" wheel too.
I guess this means that the tire contact areas are going to be changing too as you mod...the E has narrower tires with its 18 " wheel rims...I fancy these tire profiles are about the only difference I notice in the handling of the two bikes I have...I seem to favour the T on rainy days ...but any other preference gets theoretical because the E is the beater and gets chosen to preserve the shinier T...

 

[Nessism]

Don't think I'd use 14" shocks. The bike will be kicked up in the back.

 

[Gorminrider]

yes, if you're trying to "level" the bike, 18" front and rear from an E will do it... and , you will have a better gap between front wheel and its fender (if you are going to keep fenders that is...)
I've never been happy with the 19" front being sooo tight to the fender. Gravel gets pulled up under and is a stupid grinder....
But, you haven't told us where this is going. If you are heading 'twards a dirt bike,maybe the poochy "tail up" is more the way

 

[sam000lee]

I'm not totally sure what the direction will be but I'm mostly using it as an excuse to practice/improve my welding and fab skills. I'm toying with putting an xl125 tank on it and I'll be making/upholstering a seat and some leather bags for it as well as rewiring, etc.
As I mentioned before I have a GS500 cylinder/piston set and cams and eventually will get my hands on some GS500 carbs. I think I'm going to sell my CB550F project and use that money to get a Mac 2-1.

 

[sam000lee]

Don't think I'd use 14" shocks. The bike will be kicked up in the back.

Yeah I'm going to put the 18" rear on my GS450L thats currently on the road and see how it feels before hacking the passenger footpeg frame to accommodate the longer shocks.

 

[blake989]

my first post, here it goes...I just re-did a T (17" back with 19" front) and I put on a set of 14.5" rear shocks. I did adjust the chain correctly for the longer shocks, do not have any awkward forward rake (bike sits level now), and did not notice any change in road manners...haven't been above 55mph yet either

 

[sam000lee]

my first post, here it goes...I just re-did a T (17" back with 19" front) and I put on a set of 14.5" rear shocks. I did adjust the chain correctly for the longer shocks, do not have any awkward forward rake (bike sits level now), and did not notice any change in road manners...haven't been above 55mph yet either

Cool, good to know. Do you have any pictures of your bike? Did you have any swingarm clearance issues with bit of the frame that the passenger footpegs and exhaust attach to?

 

[blake989]

Cool, good to know. Do you have any pictures of your bike? Did you have any swingarm clearance issues with bit of the frame that the passenger footpegs and exhaust attach to?

I'll snap some pics tonight and try to post them, remember I'm new on the forum so that might not work yet. No interference issues and I used a Heideneau K60 120/90-17 tire. The only issue is the kickstand is too short. If you want an idea of how it will look, put the bike on the centerstand, because until I lengthen the kickstand, the centerstand is how he sits, and it goes on the centerstand real easy.

Edit. The bottom shock bolt cap nut does rub the inside of the exhaust. It appears to be the stock exhaust, and this spot does rub a little. I'm letting it self-clearance.