1981 gs850 Front Rotors on a 1979

[spacepirates]

Wanted to share my experience with this...

My stock 1979 GS850 rotors were slightly warped and I wanted to do an easy upgrade for riding in wet conditions, so I opted to get the 1980 and up slotted / drilled rotors. I also got the matching calipers. The rotors bolt on, and are the same size (to my eye, anyways). The calipers, however, do NOT fit.

'81 calipers on a '79 DO NOT WORK. The rotor bottoms out in the calipers before you can align the calipers to the mounting holes on the fork. Not awful news, though, as it seems 79 calipers work just fine (my opinion after ~10 miles of riding) with the 81 rotors.

Time will tell if the circular brake pads wear poorly, but the brakes function in the meantime, and I'm quite pleased about that.

TL;DR 81 rotors on a 79 work, but the same isn't true with calipers

 

[tkent02]

That's odd, I've used the later calipers on the earlier bikes several times, much improved braking.

 

[tas850g]

I've got 80 slotted front rotors on my 79 850 with 79 calipers. No issues here.

 

[spacepirates]

That's odd, I've used the later calipers on the earlier bikes several times, much improved braking.

yeah, that is what I was hoping for (I moved to stainless steel braided lines at the same time as I swapped rotors), but alas, it wasn't meant to be.

 

[salty_monk]

I suspect one component of what you have is from a "GL" model not a G. That would explain it as the caliper bracket is different between the G & GL.

 

[SqDancerLynn1]

There is a difference between the round and square disk brakes. It will work fine Just the round pad will over hang about a 1/16"

 

[spacepirates]

I suspect one component of what you have is from a "GL" model not a G. That would explain it as the caliper bracket is different between the G & GL.

... I am sad to admit that I did not consider this.

 

[bwringer]

I suspect one component of what you have is from a "GL" model not a G. That would explain it as the caliper bracket is different between the G & GL.

Agreed. GL parts are more common, and it's also a rare fleaBay seller that has any idea what he's selling.