GR650 Front End... Compatible with??? Like to have twin disc.

[Jedz123]

Hey Guys
I'd like to upgrade my front single stopper to a dual disc setup. The caliper and rotor look identical to the big GS 4 cylinder models( 750, 850, 1100, etc) however my GR was only equipped with forks with a caliper mount on only one side, the other fork tube is mount-less. Oddly enough though my spoked rims does have the holes drilled and threaded to accommodate a second disc and looks dead on to a stock post 81 GS750 rim . Curious if any of you have had any knowledge or experience in running forks from another GS model on a GR650. I'd also love the idea of swapping out the rear drum and running a rear disc... But one step at a time I guess. I know the GR has very similar parts to the GS line (I call it one anyway).
Thanks!
-J

 

[Steve]

Are the fork tubes 35 or 37mm? :-k

If they are 37, I have a pair of lower fork tubes that I can send your way.

.

 

[Jedz123]

She's 35mm. Thanks Steve but she takes the smaller forks.

 

[salty_monk]

If they are similar length I suspect you can just swap out the fork legs whole & bolt some calipers on... What size diameter is the rotor?

Got a decent pic to post? You might be able to put a twinpot caliper on there instead... (of course with a GS650g forke leg set this would almost certainly be possible).

 

[Jedz123]

I'm at a crossroads on which direction to go down for I'd like to upgrade to an 850 front end but if I ran 35mm forks I could easily just swap in 650 or 750 tubes and be done with it. For some reason I think you can only use a single pot type Caliper. I did contemplate just running a twin pot (if applicable) and Stainless lines, stiffen up the fork and boom be done. But the GR forks are not like traditional GS forks and I cant access the springs at the top of the tubes. I did go in on a 84 GS450E and plan on swapping the rims over to help bring a taller tire in the rear to in turn help lower the gearing a bit on the GR. Take away some of the "L" attributes that my GR has inherited like the 19" huge front rim and the tiny and wide 16" rear. It's a project to say the least...

Here's a pic of the front. (only one I got)

 

[Roger P.]

Hey Guys
I'd like to upgrade my front single stopper to a dual disc setup. The caliper and rotor look identical to the big GS 4 cylinder models( 750, 850, 1100, etc) however my GR was only equipped with forks with a caliper mount on only one side, the other fork tube is mount-less. Oddly enough though my spoked rims does have the holes drilled and threaded to accommodate a second disc and looks dead on to a stock post 81 GS750 rim . Curious if any of you have had any knowledge or experience in running forks from another GS model on a GR650. I'd also love the idea of swapping out the rear drum and running a rear disc... But one step at a time I guess. I know the GR has very similar parts to the GS line (I call it one anyway).
Thanks!
-J

If you're not stuck on using Suzuki parts, the later XS650 forks have caliper mounts on both legs. You can buy new calipers at Mikes XS, or source them from other models like the XS750-850 standards (not Specials). Shouldn't be too hard to fab up some caliper adapters. They are 35mm.

Other than that, maybe swap in a GS550E front end, which will give you dual calipers and anti-dive. You will need the triple clamps for the larger forks. Many Suzuki front ends swap between models without even needing a bearing changeout. If you don't like the 16" wheels, there will be some modding necessary to make a larger wheel work.

 

[Big Rich]

I put GS650 forks in my GR650 triple tree for the dual disc upgrade, and found out the spacing is different. Needed different wheel spacers to center the wheel, and custom caliper spacers to get them centered as well. Easiest thing to do would be to get a GS850G front end complete (minus the wheel).

As far as GS450 wheels go....... the 18" front is only drilled and tapped for a single rotor unlike the GS 19" wheels. And the rear 18" wheel won't be centered in the swingarm. IIRC, the rear sprocket needs spaced to the left about 1/2" to line up, and it is off the sprocket carrier by then.

If it's any help, a GT750 / GT550 rear wheel is pretty similar to the GR rear wheel as far as hub diameter goes. With the 18" rim and a set of spokes from eBay, you can lace up the rim to your current hub.

Edit : a rear disc brake is feasible...... but look at axle diameters first. I think the GS bikes with spoke wheels have a 20mm rear axle while the GR axle is 17mm? There are other options, but I don't know how far you want to go.

 

[RichDesmond]

...But the GR forks are not like traditional GS forks and I cant access the springs at the top of the tubes...

?? I haven't worked on a set of Tempter forks, but we have sold several sets of springs for them and haven't heard from anybody about a problem getting to the springs. Can you describe how they are different from normal?