1981 GS1000G front brake upgrade project

[Guest]

I've been doing a lot of reading here over the past couple of days, and have decided upon a course of action to upgrade the brakes on my '81 1000G. After riding the ST1100 with used rotors, rebuilt calipers, and Galfer pads, I noticed a huge difference between it and my beloved GS when it came time to slow down, so something needed to be done.

I won't go into the how-to as to taking the wheel off and such, this will serve as a parts advice guide if anyone else needs/wants to do the same thing. Thanks to salty_monk and former member 8 track for their work on this, some of the below is copied from their threads. Most of the used parts I reference were found on eBay. I do not post eBay links since they only last 90 days or less. If I posted them, someone reading this thread 2~5 years from now will experience frustration when they can't see what we were talking about since the link is dead.

This is a work in progress thread, but I hope to have it completed in a month or so. I'll follow up with some pics as I make progress.

Parts-
Brackets
Custom brackets from member salty_monk. Link to his thread $83 shipped. You will also need 2x 10mm x 40mm bolts, 2x flat washers, 2x lock washers, and 2x 10mm nuts for the bottom hole. Figure another $5 at your hardware store for these, but use at least a grade 8.8 (10.9 or higher preferred).

Calipers
2 x calipers from various bikes, mainly Kawasaki models-
EX 250 Ninja 1988 to 2007 (single caliper on right side)
EX 500 Ninja 1994 to 2007 (single caliper on right side)
ZL 600 B1 Eliminator 1995 to 1996
ZR 550 B1/B2/B3 Zephyr 1990 1992 1993
ZX 600 C1-C9 Ninja 600 R 1988 to 1996
ZR 750 C1/C2/C3 1991 to 1993
ZX 750 F1/F2/F3/F4 Ninja 1987 to 1990
ZG 1000 A9-A20 Concours 1994 to 2006
ZX 1000 B1/B2/B3 Ninja ZX10 1988 to 1990

Suzuki also used this caliper on the VX800, GS500 and the GSX1100G

I found a pair of calipers from a Concours for $42 shipped on eBay. UPDATE- they were not the right ones- they were from an earlier model. Fortunately this was resolved before shipping. If buying Concours calipers, be sure they are the dual-piston ones from 94-06. The earlier 86-93 ones are single-piston and won't fit. Shop around by model on eBay, you'll find the prices vary a lot for the same thing. It's also usually cheaper to find a pair of calipers than buying them one at a time. Be sure you are getting left and right calipers and that each caliper has the bolt for the banjo fitting in it. I found an even better deal for a pair of ZX600C calipers for $25. I think you can find decent used calipers for $50 or less, so that's the allowance for this item.

Pads
Your choice on these. Expect to spend anywhere from $20~40 per set, so budget $60. I found a set of organic EBC pads for $20/set $40 total shipped on eBay that were new old stock still in the package. Be sure the pads match the calipers you bought, and you need two sets since you have two calipers! The EBC organic pads part number I bought is FA129.

Rotors
2 x rotors, 295mm. I have posted more than you need to know about donor rotors here. It boils down to:
a) Solid GS rotor from a:
GS 550 C/N/EC/EN 77-79
GS 550 LT 80
GS 750 C/N (8 Valve) 78-79
GS 1000 C/N 78-79

b) Vented (one way, the slots will face the "wrong" direction on one side, but this is not known to be an operational problem) GS rotor from a:
GS 550 LX 81
GS 550 LZ 82
GS 550 TX 81
GS 650 GLX/GLZ/GLD 81-83 (NOT the 650G standard)
GS 750 TZ/TD (16 valve) 82-83 (NOT the 750E)

Make sure what you get is the larger (295mm) single rotor from the L/GL/TZ. The standards of this era used the smaller 276mm dual disks. Ask the seller to measure it before you buy- it will save a lot of headache when you get the wrong one.

You may be able to use certain Honda CBR rotors, but I didn't pursue those since the bolt circle was off by 2mm (GS=76, CBR is either 74 or 78 depending on the model & year). See salty_monk's update on this item below- they need to be re-drilled.

I decided on a pair of GS650G rotors. I found them from 2 different sellers on eBay for about $60 total.

Like many, I fall into the "while I'm at it..." trap. So, while I'm at it, I'm going to replace the wheel bearings (not relevant) and replace the rubber brake hoses with braided stainless steel ones. I did this on the ST1100 and it was a worthwhile investment.

Hoses/plumbing

The plumbing will be as follows (parts were sourced from Summit Racing):
Master cylinder: 10mm banjo fitting
Fragola PN 332020 AN3 teflon-lined hose w/ black plastic cover with 10mm banjo to straight AN3 female, $20. Runs from master cylinder to tee.
Fragola AN3 bulkhead tee PN 583403, $6. This tee has 3x AN3 male fittings, and a nut so you can mount it on a bracket if desired. I plan on making a small aluminum bracket to mount it in the stock location.
Fragola AN3 bulkhead nut (optional if you plan to make a bracket for the tee), PN 492403, $1.
2x Russell 18" long AN3 DOT legal hoses with a 90 degree end and a straight end. I found they were either PN 655040 ($25 each) or 655042 ($30 each), for a total of either $50 or $60. Note Summit lists two 18" hoses that are identical in the catalog. One costs five dollars less than the other. My best guess is that the more expensive one is DOT approved, since the 655040 ones I received were not DOT labeled despite the website saying they met the same DOT standard as the 655042 hoses.
2x Russell 35 degree AN3 to 10mm banjo adapters, PN 640511, $8 each for a total of $16.
Bag of 10 aluminum crush washers, PN 999210, $4.

You'll also need some chemicals & fluids- your choice on these.

The total cost breaks down as follows:
Brackets, hardware: $88
Calipers: $50 (I spent $25)
Pads: $60 (I spent $40)
Rotors: $60
Plumbing: $107 or $97
Total: $365 or $355

That's a lot of dough, but the results should be worth it. Stay tuned for updates.

[salty_monk]

GS PCD is 78mm. The spacers in the kit act as a drilling jig to drill the 74mm ones to the correct size.

[GS1000G Shopper]

Is the PCD measured outside-to-outside? I measured center-of-bolt to center-of-bolt and got like 75.9.

I've gone with the GS650G rotors, but thanks for the update.

BTW, contact me, I need to buy one of your adapter kits.

[salty_monk]

No, it's the dia of a circle that is traced through the centre of the bolts.
Maybe i'm wrong as I'm just going from memory.

[GS1000G Shopper]

I got a lot of the new parts today (to include the adapter kit from across the country), but the Fragola hose was wrong- mislabled. Fortunately Summit is good about their mistakes and have already sent out a replacement.

I have started a paper on the process and will hopefully put everything together with photos soon.

[GS1000G Shopper]

Step 1

Here goes step one. I have everything on hand except the calipers. I got the wheel off and bearings out tonight and took some photos. I'll stop this post at the point where I have the front wheel off, and will post again when I have the remainder complete. This is not a difficult job if you can use basic hand tools and you stick to using Suzuki pattern rotors. I'd urge anyone following/planning this to wait until it is completed so as to make sure the parts list is correct.

Note- left means your left as you're sitting on the bike. Right means the other side.

EDIT
See first post above for parts list.

1981 Suzuki GS 1000G
Front brake upgrade procedure

Summary of upgrade:
GS1000G used single piston calipers on small 276mm rotors. Stopping ability compromised as compared to others of that era. Upgrade uses dual piston calipers that were common on several Kawasaki models and a few Suzukis. Larger 295mm rotors from single-rotor Suzuki setup, or 296mm Honda CBR rotors (must be redrilled) are used.


Tools & materials-
General set of 3/8 drive metric sockets specifically 12, 14, and 17mm with 3” and 6” extensions
Set of metric hand wrenches
Phillips head screwdriver
Flat tip screwdriver
Hammer
Standard pliers
Small cotter pin
Turkey baster or other means of removing brake fluid from master cylinder
Rags/paper towels
New brake fluid
Wheel bearing grease for speedometer drive
(Optional for Honda rotors) Drill or drill press and 8mm or 5/16" drill bit

Procedure:

• Drain fluid from master cylinder using turkey baster.
• Unbolt hose from master cylinder- use rag to catch any remaining fluid
• Lift and support bike by frame so front wheel is off the ground. I used a pair of jack stands under the engine guards.

• Look at wiring by the factory tee- my bike has a Vetter fairing so there were some wires that needed unplugged or else you’d have to remove the hose to the left side caliper.

• Unbolt tee fitting from frame.
• Unbolt calipers with brackets from forks- 14mm socket x 2 bolts per side.

• Remove calipers w/ hoses attached- everything up to the master cylinder. I was able to remove my entire brake system w/o unplugging anything by pulling the left caliper through the opening in the wire harness by where the tee was. You'll have the hose from the mater cylinder, the tee, and both hoses and calipers as one unit.
• Unscrew speedometer cable from sender.
• Remove front wheel- pliers to remove cotter pin, 17mm socket for nut on right side, 14mm socket for pinch bolts underneath (do not need to remove), slide axle bolt out while holding wheel up- I used a 6” 3/8 drive extension to hold the right side of the wheel in place while I did this- I slid it in as the axle bolt slid out.
• Optional- Replace bearings now if desired.
• Remove old rotors- 12mm socket and flat screwdriver to bend down lock tabs.
• Clean parts to be reused. Optional- this includes re-packing the speedometer drive with new grease. There is a snap ring that holds some metal parts on, the trick is popping out the rubber seal under them. If you can get it out using a small flat tip screwdriver, it’s a simple matter to de-grease it and pack it with new wheel bearing grease. Installation is the reverse of the disassembly.
• You can also lube the speedometer cable now.
• Make sure you clean out the spacers (one on the right side that falls off with the wheel, and one each under the axle pinch nuts) where the axle bolt will be and place a light coating of wheel bearing grease on them.

Here are the parts that are ready to be cleaned (left to right and bottom to top)-
Internal spacer (you won't see this unless you're replacing wheel bearings)
Plate from left rotor
Axle
Bolts (6) with lock brackets from left rotor
Speedometer sender
Right side wheel spacer


Here is a pic of the old rotor on top of the new one to show the difference in size:


More to follow soon.

[GS1000G Shopper]

Step 2

Here's step 2:

• Install new rotors. There was a plate on top of the left side rotor on my bike, so I reused it. Torque nuts to 11~18 ft lbs. Tap the lock plates back into place.
• The manual says to torque the pinch nuts under the axle to 11~18 ft lbs first, but I found it was easier to leave them loose until the axle was in place, and then torque them. Reinstall front wheel- align speedometer sender and spacer, lube axle bolt with wheel bearing grease and reinstall it. You may need to tap (not beat) it into place with a hammer.
• Torque axle nut to 26~37.5 foot pounds (you can hold the opposite side by sticking a Phillips screwdriver through the hole) and install new cotter pin. The hard work is done!

More to come!

[GS1000G Shopper]

Summit sent the replacement top hose today, and it was the same wrong one. Apparently a batch were mislabled.

The calipers also arrived, and I will update the above posts. The hoses I have are too long, the AN to banjo adapters cannot be straight, and you need a 10mm x 40mm bolt to secure the bottom of the salty_monk bracket.

So it's hurry up & wait.

[GS1000G Shopper]

Pics from today. I'm on parts hold until I get the right top hose, shorter caliper hoses, and angled banjo fittings. I'm also going to reseal the calipers since when I was cleaning them I noted the rubber slide/pin seals were in bad shape. The pistons moved easily, so that was good news. I'll paint them red once all reseal work is done.

Kawasaki calipers as received:


Test fit, note added 10mm x 40mm bolt in lower hole.

[salty_monk]

Looking good. Don't forget to loctite your bolts (blue).

[GS1000G Shopper]

I now have the calipers cleaned and painted, and the 18" hoses and 35 degree banjo adapters arrived today (apparently I need to update the parts listing again since these are not marked DOT like the last ones were). I'm waiting on the top hose (hope I get the right one this time) and the rubber seal parts for the calipers.

Here's a pic of the test-fit:


I took one of the small aluminum bracket I made. It may be hard to see, but it's just a piece of flat 1/8" thick aluminum with a 3/8" and 1/4" hole drilled in it. The tee goes in the 3/8" hole and the OEM mounting bolt goes in the 1/4" hole.

[GS1000G Shopper]

Completion & final comments

I got the correct hose today directly from Fragola.

The job has been completed, and I will add some pics of both sides and the master cylinder as well as the hose packages below. The correct hose is on the left side, as evidenced by the banjo fitting.

Comments-

• The 18" hoses are still a bit long. I looked around and didn't see any 17" ones that would work. Of course, if you made your own this would not be a factor.
• Due to the 35 degree banjo at the caliper (needed to clear the bleeder), this makes the hose do an S-curve when it's placed in the factory holder.
• The bracket I made to mount the tee needs to be offset to the right side a little. I don't see where it will be a problem, but the left side hose is a little close to the fork tube. I angled that hose to the rear a little for better clearance, and since the hoses were a little long.
• The master cylinder boot works OK. The Fragola AN3 hose is a little smaller than the stock one, but I doubt anyone would notice this.

I have not done any hard braking, and have only run it up to 10~15 MPH on my driveway. I want to let the pads bed in w/o glazing. So far, they seem to be a lot better than the old setup.

Here are the pics:

[tilly]

Very Nice

I'm new this forum and this is exactly what I looking for on my 80' GS1100L. Brakes are just lame even after replacing brake line with stainless braided lines and rebuilding everything. Everything looks the same on your 81' so I'm assuming this mod will work. In the post you mention a parts list but really didn't put any part numbers or even year model of such items as the 296mm Suzuki rotor or the Kawaski caliper year model of bikes such for parts. Can you take the time remember what you used so I can find them & duplicate this great mod?

Thanks for any effort.

[GS1000G Shopper]

I'm new this forum and this is exactly what I looking for on my 80' GS1100L. Brakes are just lame even after replacing brake line with stainless braided lines and rebuilding everything. Everything looks the same on your 81' so I'm assuming this mod will work. In the post you mention a parts list but really didn't put any part numbers or even year model of such items as the 296mm Suzuki rotor or the Kawaski caliper year model of bikes such for parts. Can you take the time remember what you used so I can find them & duplicate this great mod?

Thanks for any effort.

Please refer to the first post on page 1. I'm figuring you missed it, since that is where everything you asked about is mentioned. I try to keep everything in the first post due to people not wanting to read the entire thread for the info.