To replace caliper pistons or no? (Last dumb question from me for a while, I promise)

[LilBeaver]

I am planning on rebuilding my front calipers as I suspect one of my brakes might be dragging. I pulled the calipers out and upon inspection the pistons were as smooth as can be except for the small section that sticks out of the caliper while in the normal position. Running my finger across them I can feel that they are a little rough. Some of it is just dirt and some might be actual damage to the piston itself.

 

My question is: How much pitting is okay in the caliper piston before it ought to be replaced? It appears that any roughness in the piston itself remains outside the caliper when a set of fresh pads are installed therefore I would presume that it is fine to go ahead and not replace these and just polish them as much as possible before reinstalling in the rebuilt caliper. I have included a few pictures of what I am looking at here - I know it is a little hard to tell, but it was pretty much the best I could do.

 

Also, is there anything else I ought to be checking for on these? I did notice more dirt build up on one of the caliper's pistons than the other, which leads me to believe that something is wrong with that particular caliper (ie leaky seal or something like that).

 

Thanks for putting up with my dumb questions...

[RedRider]

Beav,

 

I would reuse these calipers as is. You may want to run a little emery cloth around it to clean 'em up a little, but they look pretty good. What condition are the boots in?

 

RR

[LilBeaver]

Beav,

 

I would reuse these calipers as is. You may want to run a little emery cloth around it to clean 'em up a little, but they look pretty good. What condition are the boots in?

 

RR

 

Yea, when I get them out I was planning on polishing them up as well as I can (if I go ahead and reuse them - which at $50 per set and the condition of these, I think I will)

 

I have not removed the pistons yet to inspect anything else and I have not looked very carefully around the piston to really get a good evaluation of the boot itself.

[skydoc_17]

Hey Rick,

What you are seeing on the outer edge of the pistons is a combination of brake fluid and the dust that comes off of the brake pads. It whips up into a really good lapping compound. After removing the pistons, (don't use vice grips!) I check the pistons with a micrometer, that's when you know if they are junk or not. I clean them with brake cleaner and polish them with a rag wheel and polishing compound on my bench grinder. The seal kits are the real killer! Check out the cost of those kits before you put a bunch of time into the pistons.

 

If you want to come into the 21st century with your braking, check out this option:

 

http://www.venturerider.org/classifieds/showproduct.php/product/2445/cat/7

 

If you have other questions you can PM me if you like. Good Luck with your brake project,

Earl

Edited February 3, 2010 by skydoc_17
Didn't notice he had a Second Gen.!

[LilBeaver]

Earl:

 

The best I could find for a complete seal kit (for both front calipers) was around $33 + a few dollars shipping. I didn't think that was too bad for the complete seal kit.

 

I did take a look at the set that you were offering and have been thinking about that too. If I cannot reuse my pistons I think I'll go with your set for sure since the pistons would run me ~100 for a complete set and you've got quite the deal put together there . (The only downside to that is that my bike will be out of commission for the time it takes me to get those from you...)

 

Thanks,

Rick

[skydoc_17]

Hey Rick,

I forgot you Texan's are still riding down there! (22 degrees F, snowing here!)

I could have that R1 kit to you by the first of the week but if you are careful removing the pistons they should be just fine. Clean those pistons good, replace the seals and you will be good to go.

Earl

[Bummer]

So Skydoc, any thoughts on where to pick up a 14mm brake master cylinder to go with those blue dot calipers? Aside from Yamaha, of course.

 

Also, have you tried putting one of the spare two piston calipers on the back to replace that overly grabby four piston job? I'm afraid it would take an 8mm rear master cylinder (which probably doesn't even exist) to make that work properly, but I haven't actually tried it yet. (Everything's in place for the test run, just waiting for the roads to thaw...)

[skydoc_17]

Hey Steve,

The Bore on the Second Gen. Front Master Cylinder is 5/8" (.625" or 15.87MM). I am a little confused about WHY you would want to go to a SMALLER Front Master Cylinder on your Second Gen. VR.? By design, the R1 calipers have a much larger "sweet spot" as far as brake feel is concerned. As far as that "Grabby" rear caliper is concerned, I personally have installed an R1 caliper on the rear of my scoot and did away with any lock-up problems I had. Steve, I would be happy to set up a kit for you that has the rear R1 Caliper included. If you are interested, PM me and we can work out the details.

Now back to the regular thread! Sorry!

Earl

[Bummer]

If LilBeaver does move to R1/R6 calipers he may want to know about the front master cylinder issue. The stock front mc is 5/8", which is pretty close to 16mm. The R1/R6 calipers use a 14mm mc. Mismatching the mc to the caliper can lead to a more "digital", presumably on/off feel, possibly with less ability to smoothly modulate braking. Not saying it won't work, just that a lot of the folks who have made the caliper change wound up making the mc change also, for a better feel.

[SilvrT]

Rick... when your in the process of putting it all back together, get a tube of "brake lube" aka "anti-squeal" and apply a small amount to the parts of the brake pads (the backing plate & other metal parts, not the brake pad surface) that touch or rub against the caliper points/pistons and other similar points.

[LilBeaver]

Hey Rick,

I forgot you Texan's are still riding down there! (22 degrees F, snowing here!)

I could have that R1 kit to you by the first of the week but if you are careful removing the pistons they should be just fine. Clean those pistons good, replace the seals and you will be good to go.

Earl

 

 

My plan was to drain the fluid, disconnect the line and use compressed air to (gently) blow out the pistons and then go from there.

 

If LilBeaver does move to R1/R6 calipers he may want to know about the front master cylinder issue. The stock front mc is 5/8", which is pretty close to 16mm. The R1/R6 calipers use a 14mm mc. Mismatching the mc to the caliper can lead to a more "digital", presumably on/off feel, possibly with less ability to smoothly modulate braking. Not saying it won't work, just that a lot of the folks who have made the caliper change wound up making the mc change also, for a better feel.

 

This is good to know, I hadn't considered there being difference like that.

 

Thanks for the input.

[LilBeaver]

Rick... when your in the process of putting it all back together, get a tube of "brake lube" aka "anti-squeal" and apply a small amount to the parts of the brake pads (the backing plate & other metal parts, not the brake pad surface) that touch or rub against the caliper points/pistons and other similar points.

 

 

Yup yup. Makes a world of difference. Thanks for the reminder!

[Bummer]

This is good to know, I hadn't considered there being difference like that.

 

I really am looking for a 14mm master cylinder. This is a strong suggestion from both Squeeze and Pegscraper. I've also found write-ups about it, all suggesting the change in mc to match the change in calipers. I converted to blue dots but I haven't tested 'em yet. (Haven't gotten to ride since mid Dec. Twitch. Twitch.)

 

I also put one of the stock two piston calipers off the front onto the back to try out. I'm hoping for a weaker grip out of it, and as a result, less chance of a lockup.

 

Might get to go for a ride tomorrow to test out my brake changes. Supposed to be 40 and dry. No chores to stop me. (Fingers crossed.)

[LilBeaver]

...

 

I also put one of the stock two piston calipers off the front onto the back to try out. I'm hoping for a weaker grip out of it, and as a result, less chance of a lockup.

 

I'll be interested in reading your review of the new fronts as well as what you've done with the rear. I have yet to have a real problem with the rear locking up despite having a few 'emergency' stops already BUT if I could get a wider range of play with the rear brake, I would much prefer that. Since that would definitely allow a wider range of control at low speed maneuvering as well as less of a chance of the lock up.

 

Might get to go for a ride tomorrow to test out my brake changes. Supposed to be 40 and dry. No chores to stop me. (Fingers crossed.)

 

but shhhhhh... Don't want any of those chores to sneak up on you - I hate it when THAT happens.

Edited February 3, 2010 by LilBeaver

[Squeeze]

Wild Star/Raiders have 14mm Piston Masters with 1 Inch Handle Bar Clamp in both Versions, black or chromed Master.

 

It's not like a 5/8" Master wouldn't work. Most of those Guys i know say the 14mm Master works better, myself included, some say it's a must have, but there are 2 or 3 who love the Bite of the 5/8" Master. Most People love the 14mm better, because it allows much better Control and is much more sensitive. You should ride your Bike with the 5/8" and if you're not completely satisfied, get a 14mm and be a happy Camper.

[LilBeaver]

Got it all taken care of today. I have some pictures, but since it isn't any thing too exciting I will not post them.

 

A big thanks to Skydoc_17 (Earl) for the help

 

It was a pretty straight forward process although a little time consuming due to how dirty my calipers and pistons were. But, got-r-done and am happy with the results.

[skydoc_17]

Hey Beav,

I am glad to hear that it worked out for you. Few things feel better that doing work on your own motorcycle. Plus you saved $300.00 if you would have went to the stealer!

Good Job,

Earl

[LilBeaver]

Hey Beav,

I am glad to hear that it worked out for you. Few things feel better that doing work on your own motorcycle. Plus you saved $300.00 if you would have went to the stealer!

Good Job,

Earl

 

NO KIDDING...

 

 

I really enjoy working on my own vehicles and especially when things go smoothly like they are supposed to... even getting the screws out of the reservoir covers (that were damaged by the mechanic that changed my tire trying to do me a favor... Long story, but it ends with I now have a jack and no one will be touching my scoot without me around again) backed out with an easy out just like they are supposed to work.

 

anyhoot, now I've got to get a decent 'check ride' in... Just for good measure