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Old 12 Aug 2006
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Exclamation R80 Gs Basic brake and frame reinforcement?

Hi all,

1. I would like to improve the brakes of my R 80 GS Basic. Grant used a new front disc of a R100 GS with 6 caliper brake. The question is: Any large enough disc from any bike or seller suits to my bike or should I use a certain one like Grant did?
Can I change the rear drum brake with a disc brake?

2. Is my bike really need the frame reinforcement? If yes what do you recommend? How to do it?

3. Last one about the main lights: Can I change the main lights to Xenon or halogen one? Does changing only the bulb enough?

Thanks a lot for the experiences and helps,

Best regards
"where the traveller goes, nobody knows ! "
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Old 14 Aug 2006
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Harrison brake

I fitted a 6 pot Harrison brake which turns braking into a two finger exercise. By judicious choice of brake pad and rotor material, the braking can be improved even more. The R100GS is terribly underbraked with only 1 disk and a 2 pot brake unit. There are other mods such as modifying a 4 pot from another BMW or even changing the forks to accomodate twin disks. I've found the Harrison not entirely fault free. Because the unit is so big (long), it puts a lot of mass forward of the fork which makes the bike more susceptible to a "tank slapper". Easy, bolt on mod though - definately recommended.

Go to http://bcostell.smugmug.com for pictures of beefing up an R80gs subframe and some good looking mods.

I had a 55W spot light mounted on the roo bar which improved long distance at night. It was hooked up so it was live only on main beam.
Tim ('91 R100GSPD)

The only baggage you carry should be in the panniers

Last edited by Tim Wood; 14 Aug 2006 at 15:40.
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Old 6 Sep 2006
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Wink G/S improvements

If you haven't already, do a seach of the BB on the past posts for 'GS brakes' or 'R100 GS'. There has been some good discussion on this subject on several threads. There are several options, even some bolt on ones. I have seen several conversions now using other (Suzuki) large rotors and the stock or other calipers.

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Old 6 Sep 2006
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1)a Front brake - yep people change these to get more braking. The harrison 6 pot does wonders - but it costs when running are high - you need 3 pairs of pads to replace the padS in these things rather than 1 pair of pads for otehr calipers.

1)b rear brake .. don't even think about changing it for a disk .. way too complicated for the gain. You have teh cable operated brake ? Not the rod? Cable operated ones can do with a change to teh leverage ratio .. documented on UKGSer...

2) Yes - loop at the HPN photos for the rear sub frame reinforcement .. tube add at the bottom. Up to you if youwant to do the main frame .. but definatly teh rear if you carry luggage.

3) Try not to ride at night.. that is the time for eating, washing and sleeping. The original standard globe is 55/60 watt quartz halogen. If you change to a higher wattage - put relays in so you don't burn out the bm switch gear and wire them up so you get the most ligh from them.
Regards Frank Warner
motorcycles BMW R80 G/S 1981, BMW K11LT 1993, BMW K75 G/S
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Old 6 Sep 2006
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[QUOTE=Frank Warner]1)a Front brake - yep people change these to get more braking. The harrison 6 pot does wonders - but it costs when running are high - you need 3 pairs of pads to replace the padS in these things rather than 1 pair of pads for otehr calipers.

Not to mention the 6 seals (and maybe pistons) needed for a rebuild, which you will have to do frequently, as all the 6 piston calipers I have looked at don't have dust seals.

Also, the R100/80 GS carries it's caliper in front of the fork, which means that a 6 piston caliper is mounted backwards, and will cause uneven wear of the pads. The pistons are not the same size front to back.

The stock R100/80 GS caliper isn't that bad, and actually has a very larger surface area. I personally think that changing the disk to a larger disk is plenty adequate when combined with braided steel lines. This alows you to keep the stock caliper and master cylinder.
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Old 6 Sep 2006
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Update - I just dumped the PM differential 6 piston caliper - for a Harrison Billet-6. Big improvement, much better braking.

Problem with the PM differential caliper is that it was BACKWARDS on my R100GS forks - it was designed to be mounted behind the forks, not in front.

Lots of discussions with Harrison while they fabricated a mount - (I have the 320mm disc on mine, so the Harrison standard R100GS bolt on doesn't work.)

Upshot of it all is:
1. Dust seals not needed, as they use a hard-anodized piston, which doesn't corrode like the usual chromed steel piston. Just give it a wash occasionally to keep the area clean, especially when riding in mud! Normally even at high mileages the pistons do not need replacing.

2. They also don't find they need a differential bore setup with the separate pads, solving that problem.

3. The easy way to go is to buy their standard bolt on Billet-6 or 4 piston version for the R100Gs or R80G/S. 306 pounds plus vat for the 6 piston, not sure the price of the 4 piston, but it's on their website http://www.billet.co.uk/
If you need a custom bracket because of an oversize disc - or whatever reason - it runs around 75 pounds, and they'll do it on the spot if you make an appointment.

Is it worth it? I'd have to say that any improvement over the standard is worth whatever it costs!

Any good 4 piston brake is way better than the standard - the R80G/S front end originally on my bike got a Performance Machine 4 piston that worked well. The 6 piston calipers of course are definitely better, but cost more. It's up to your budget, but two-up and loaded on these bikes is, in my opinion, dangerous. You owe it to yourself - or AT LEAST your passenger if you don't care about yourself, to have a decent brake.

hope that helps a little - I've had 4 different brakes on mine and they were all much better than the original.
Grant Johnson

Seek, and ye shall find.


Inspiring, Informing and Connecting travellers since 1997!
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Old 30 Sep 2006
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I called Billet and they recommend the 'mini six' for an R100GS PD - anyone fitted one of these to their bike?
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Old 1 Oct 2006
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I have a six pot fitted to my r80gs

just would like to sort out the back brake now
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Old 1 Oct 2006
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Aother thing to consider when purchasing a new rotor. The stock R100gs rotor is stainless steel. Although it stays nice and shiny and will probably outlast the bike, SS has a very low coeficient of friction. This is one of the reasons the R100 has such lousy brakes, apart from the small rotor and small caliper. The best rotors are made of ductile iron, they stop you like crazy!! These are used on race cars ad GP bikes. If your retrofitting, you can get some great brake systems from KTM Racing. I went with a 310mm ductile iron wave rotor and Berringer four-pot caliper. I use a stock BMW 12mm master cylinder. I can actually lift the back wheel off the ground with two fingers! The advantage of the wave rotor is it equals the surface area of the rotor from the bottom of the brake pad to the top, so your pads wear evenly and actually last longer. All this wasnot an easy task though...i had to build a custom tripple-clamp and mounted a set of WP4860 forks from a KTM. They had to be shortened by 4 1/2" and re-sprung, basicly the same forks you find on the 950. You can find them an e-bay for $500, another $400 to get them re-worked and shortened..and in the end WELL worth the effort!!
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