MKI to MKII rear brake upgrade problem

[dingy]

I need some help on the MKI to MKII brake upgrade.

 

My rear swingarm is different on my 83 compared to my 88 donor bike

 

The pin that the caliper bracket slides onto is a different dia. between the two models.

 

The 83 has a smaller dia. pin on swing arm that matches the original caliper bracket.

 

The 88 has a larger pin that is welded to the swing arm, and it matches the 88 caliper bracket.

 

The 88 bracket, when put on the 83 swing arm flops around.

 

What am I missing here.

 

Bracket at top of picture is 88, bottom is 83.

 

Hole is also slightly elongated in 88 bracket, by about .080". But there is no obvious signs of wear or fatigue. Hole is longer front to back than top to bottom.

 

The holes are the same center line distance, picture is distorting this .

 

Gary

[Rocket]

Why not fit a bushing into the 88 bracket, to match the 83 bracket hole size.....

[MiCarl]

Why not fit a bushing into the 88 bracket, to match the 83 bracket hole size.....

 

That would be fine, unless Yamaha had a reason to beef up the swing arm pin...

 

Gary, the MKI bracket looks like the holes are bored where the MKII looks like they're cast or forged. That would easily explain the reason for the out of round hole. Might also explain why they went to the larger pin.

[dingy]

I thought changing to MKII brakes was a fairly common upgrade.

 

Has this ever popped up before?

 

Putting a bushing in is an option, I would have to have one machined. And it would have to have set screws in it to keep it on the swing arm.

 

Easiest option I can see is using the MKII swing arm.

 

MKI arm has been sandblasted & painted though.

 

Gary

[IH Truck Guy]

I thought changing to MKII brakes was a fairly common upgrade.

 

Has this ever popped up before?

 

Putting a bushing in is an option, I would have to have one machined. And it would have to have set screws in it to keep it on the swing arm.

 

Easiest option I can see is using the MKII swing arm.

 

MKI arm has been sandblasted & painted though.

 

Gary

 

I would get a hold of Skydoc17..He's the man with the plan when it comes to the braking system on the 1st Gens..

[Condor]

I need some help on the MKI to MKII brake upgrade.

 

My rear swingarm is different on my 83 compared to my 88 donor bike

 

The pin that the caliper bracket slides onto is a different dia. between the two models.

 

The 83 has a smaller dia. pin on swing arm that matches the original caliper bracket.

 

The 88 has a larger pin that is welded to the swing arm, and it matches the 88 caliper bracket.

 

The 88 bracket, when put on the 83 swing arm flops around.

 

What am I missing here.

 

Bracket at top of picture is 88, bottom is 83.

 

Hole is also slightly elongated in 88 bracket, by about .080". But there is no obvious signs of wear or fatigue. Hole is longer front to back than top to bottom.

 

The holes are the same center line distance, picture is distorting this .

 

Gary

 

I don't think anyone has ever tried to upgrade the rear....except Earl maybe... Since the rear braking is such a small part of the overall braking available it might be easier to just install HH pads and get a mild increase. That said it would be interesting to see what you come up with Gary.

[bongobobny]

You can always insert a hard rubber bung like I did and drill out the cfenter to the correct diamewter. My reasoning behind the rubber was to damper out any vibrations from the rotor, etc. Haven't had a chance to try it out as the wiring harness fried before I had a chance to I also considered a solid rubber sink stopper the right diameter...

[dingy]

You can always insert a hard rubber bung like I did and drill out the cfenter to the correct diamewter. My reasoning behind the rubber was to damper out any vibrations from the rotor, etc. Haven't had a chance to try it out as the wiring harness fried before I had a chance to I also considered a solid rubber sink stopper the right diameter...

 

 

I was concerned about the bushing coming out.

 

There is nothing to hold it in on the inboard side.

 

Went to plan B, stripped, sandblasted, primed & painted the 88 swing arm.

 

I hope nothing else is different on it.

 

At least I have a real pretty 83 swing arm spare now.

 

Gary

[bongobobny]

Yah!! I epoxied it in...

[dingy]

You can always insert a hard rubber bung like I did and drill out the cfenter to the correct diamewter. My reasoning behind the rubber was to damper out any vibrations from the rotor, etc. Haven't had a chance to try it out as the wiring harness fried before I had a chance to I also considered a solid rubber sink stopper the right diameter...

 

Yah!! I epoxied it in...

 

Ok I'm going with plan 'C'.

 

Using Bob's idea of epoxying in a plug.

 

Back to MKI swingarm.

 

I used a Test Tube style stopper from Lowes.

 

Sanded it down a little on large end and used Marine grade epoxy to hold it in.

 

Drilled a 1/2" hole in center for pin on swing arm.

 

This feels much better than the MKII mount with metal to metal, loose fitting contact.

 

Gary

[Condor]

The next time try using 3M 5200 caulk. That stuff will stick to anything and it will not come loose... yet will stay plyable. I generally have to use a hacksaw on the stuff to remove a deck fitting off a boat. Not fun.. 2-part Epoxy will form a hard material that will crack with stress. Just my 2 cents...

[elag]

Just a thought. Why not just mig weld around the pin to expand the diameter, then grind round and smooth to fit the hole on the bracket? This would be much stronger then any epoxy or rubber spacers. It would even strengthen the pin to equal the MKII's larger pin.