Fork Tube Upgrade

[Indysteve]

Hey guys and gals,

First post so be gentle please.
I am working on rebuilding and updating a '79 GS850.
I long ago purchased a '82 GS1100G for use as spares and upgrades.

My plans are to swap out the front wheels for the slotted rotors.
I planned badly and thought the calipers would be a direct bolt on swap as well.

The question(s) I have are:
Should I be able to swap over the fork tubes to the 1100 so I can bolt on the newer caliper?

What fun will I have in possibly swapping out the rear wheel as well?

Should I use the 1100 Master Cylinder for the fronts or upgrade to aftermarket?

I already plan to install braided lines to upgrade hoses.
Should I go to a double line on the front or keep the existing setup?

What other adjustments am I forgetting?

Thanks for any and all help!!

[TheCafeKid]

Ok. So first, the fork tube diameter between the two bikes is the same, no upgrade there. Internals are essentially the same or as near as makes no difference. So no upgrade there.

Recently went through the options of using the newer slotted rotors on bikes with solid rotors. Will work but the calipers will have to go with the rotors as I'm not sure the 79 didn't use the old round pad type brake pads. Those WON'T work on the other, though over all the rotors are the same diameter, the actual brakig surface I believe to be different.
You may find that the 79 forks won't allow fitment of the newer caliper due to bolt spacing, but I'm not sure. I know i was going to use 1100G forks on my 1000G but the calipers wouldn't work because the hanger spacing was slightly different and I didn't have the other hangers. If you have both, you may be fine.

Rear wheel, keep your stocker. No upgrade. In fact the inner spline on the 1100 wheel is a downgrade. They were soft and prone to stripping out.
If you like the style better, you can swap, but swap hub splines as well. Ther will be a spacer change to be made, as the new wheel has a floating style rotor and the hub is different. You'll want to use the stock spacers from the 1100G on the axle as they're different than the 850 of that year. (yes I've done it. Not nearly as "difficult" as an 1150 to 1100 swap. Ha. Ha. )

[TheCafeKid]

On the MC. SS steel lines is a fabulous idea. However if you want more stopping power, use a 14mm MC from a single disc GS. There's also a guy on eBay that makes replacements that are quality ones for about $80. 14mm is smaller that the stock bore. Use two lines with a longer banjo instead of the stock splitter. Bleed the ever living snot out of it. The brakes will stop your face off with this set up so be forewarned.

[Nessism]

I don't like the 14mm master idea, it makes the brake lever feel mushy with a soft lever feel. You can use either dual disc master, you don't need the 1100 version. I recommend using the best one of the two you have.

As for the wheels, the 1100G wheels are tubeless so I'd go with them unless you have two tubeless Suzuki star pattern wheels. It's typical for the early G's to have one tube type and one tubeless. The 1100G front wheel is wider too so that's a bonus (although the 1100GL is not wider in case your parts bike is an L type).

As for the caliper spacing, I think it's the same. The later calipers are better than the round puck version though so I'd go with them.

[TheCafeKid]

I don't like the 14mm master idea, it makes the brake lever feel mushy with a soft lever feel. You can use either dual disc master, you don't need the 1100 version. I recommend using the best one of the two you have.

As for the wheels, the 1100G wheels are tubeless so I'd go with them unless you have two tubeless Suzuki star pattern wheels. It's typical for the 1000G's to have one tube type and one tubeless. The 1100G front wheel is wider too so that's a bonus (although the 1100GL is not wider in case your parts bike is an L type).

As for the caliper spacing, I think it's the same. The later calipers are better than the round puck version though so I'd go with them.

I though the same thing on the MC Ed, but the ZRX guys swear by using the smaller bore MC, from a single disc Kwacker. I did it on Simons 750 that I retrofitted dual disc to and retained the single disc MC and the lever feels less mushy than any GS ive ever ridden. Of course I also swapped to SS lines and it took quite a bit of bleeding but seriously that lever is solid.
I'd mistakenly used a single caliper MC on my 1100 and it did feel mushy. But it also had the stock lines on it. Now, I used an aftermarket one on there and the stroke may have been longer as well. But for whatever reason when I did it on that 750 it has the single best brakes on a GS I know of. Almost stops as well as my ZRX with all it's six piston goodness. Almost. So I dunno.

[Guest]

I had the rotors and calipers from an '82 1100 on my '79 850, direct swap they bolt right up. It has Salty Monks "twin pot" set up on it now.

[hampshirehog]

Calipers and rotors should swap straight over. Unless you've got some L bits?

[TheCafeKid]

I had the rotors and calipers from an '82 1100 on my '79 850, direct swap they bolt right up. It has Salty Monks "twin pot" set up on it now.

Ok. Like I said I wasn't sure. Was pretty sure you couldn't use one without the other. That's all I Figured.

[Indysteve]

Ok, so I thought I could do a direct swap of calipers and wheels with rotors, but I measured bolt difference and I thought the 850 was a little closer on the bolt pattern.
Maybe I need to re-measure those puppies and see again.

I am sure the 1100 is a G as I have the title as well, unless the title lies?????

Is there any benefit from swapping forks then at all?

My only reason for possibly swapping the rears was to get the slotted rotor.
Should I just unbolt the rotor from the 1100 and attach it to the 850 then or is there a spacing issue to deal with?

I had read through an earlier thread that mentioned using Kaw calipers with a bracket that would bring these even further along.

Can I achieve the same stopping power with a simple MC swap or do I need to also install double line fronts?

Thanks all!!

[Steve]

I would not recommend the 14mm master cylinder unless you are using stainless brake lines.

I think, though, that you would still be happier with the larger unit that came on the bike for the dual disks.

If you are keeping rubber brake lines , I would definitely stay with the larger M/C.

.

[TheCafeKid]

You can't simply swap the rotor from the 1100 to the 850 rear. Entirely different animal. Take a closer look at how they're mounted.