rear brake spacers

[barend]

I'm replacing the pads on my rear brake and would like a quick confirmation/correction about the thickness of the spacers. I measure the spacers between the caliper and the caliper bracket arm at 4mm and the one between the swing arm and caliper bracket appears to be 3mm. (I'd have to pull the wheel to make sure.) Is this correct?

 

Added question. should the disk be installed based on rotation or is that subject to which disk if at all?

 

I notice the outside pad is not flush with the face of the disk, piston problem???

 

Thanks!

 

Oh, if you missed it in my profile it's an '83

Edited February 19, 2012 by barend
added questions

[greg_in_london]

About the big washers - it sounds okay, but someone else will have a look at theirs and jump in, I'm sure.

 

Rotation of the disk ??? Is there more here that you're not mentioning ? Generally it's bolted on and you don't touch it. I thought all three disks were the same and you can't really get them the wrong way round, though if they had different part numbers (you should find the parts list if you search the site or look at an online fiche) I would admit I was wrong. It's not something people ask, so I wonder if you have a particular reason for mentioning it.

 

Pad not flush with the edge of the disk ? You mean it's wearing at an angle ? A picture might help here. I've had other bikes that wear at an angle because the calliper didn't move smoothly on the slides, but the Venture has two piston callipers. Could you elaborate ?

[barend]

when I bought the bike in august '08, the rear brake was destroyed due to a missing, incorrectly placed or wrong spacer (I forget which one, it's been a number of years and the shop did the work) They installed an aftermarket disk. I discovered (much) later that the brake disk was getting hot while riding and subsequently while spinning the wheel on the center stand that it rubs in one spot. I'm trying to determine whether a wrong disk was installed, or mayheps an incorrect installation. Should have measured the disk's thickness, but I forgot, I believe it's supposed to be 5mm.

 

As far as the caliper, doesn't the MkI only have a one sided piston? I may have to rebuild it, though that was supposed to have been done back then as well.

[skydoc_17]

Hey Barend,

If the caliper is only dragging in one spot, then the rotor is warped. You can confirm this with a dial indicator on the face of the rotor. This intermittent contact with the caliper could cause excess heat, and can cause the caliper to drag. The rear MKI Rear Brake Caliper is a 2 piston caliper. If you go to this link, on the second row, to the right of the main pic, you will see a disassembled rear MKI Caliper:

http://www.venturerider.org/classifieds/showproduct.php?product=3771&title=first-genmki-rebuilt-calipers&cat=22

Usually if a rotor is so warped that it is affecting the caliper, it should be replaced. If the rear rotor is an aftermarket non-vented EBC type rotor, (basically a solid, flat disc of S.S.) I have had fair luck straightening these rotors with a hydraulic press. (your mileage may vary) But here again, without the proper equipment, and a good "feel" for what you are doing, replacement is the easiest way to go here. Barend, with the added weight of your Hack, and the "small brakes" that came on the MKI to begin with, it's no wonder the rotor is shot, and the caliper is dragging. This is not as much about how you ride, as it is about the amount of weight you are trying to stop with the underpowered braking system on your MKI VR.

Earl

[dingy]

Should have measured the disk's thickness, but I forgot, I believe it's supposed to be 5mm.

 

As far as the caliper, doesn't the MkI only have a one sided piston? I may have to rebuild it, though that was supposed to have been done back then as well.

 

That helps with something that confused me from your first post.

 

The 83 stock rotors are 298mm x 8.5mm thick. If it has been replaced with a 5mm, then someone may have added spacers between the caliper and the caliper arm to center the caliper on the now thinner disk. There are not normally spacers at this point. The 3.5mm thinner disk would need the caliper to be shifted towards the rim by 1.75mm to center it.

 

All 83-85 1st gens have twin piston calipers, one on each side. The 86-93 have quad piston calipers.

 

The rear rotor on an 86-93 is a 320mm offset design, different from the 83-85's. Fronts on 86-93 are 282mm x 7mm

 

The 83-85 rotors have different part numbers for the front left rotor. The right front & rear are the same. If this is anything like the 86-93 rotors, this difference is very minor, and I think it wouldn't be a catastrophe to interchange them. Not positive on the last one though.

 

Gary

[dingy]

I just check my spare parts stash, and I have a very good MKII rotor & caliper & caliper mount arm & stainless brake line that I am not using.

 

I used this setup on my 83 for a couple of years. Caliper arm has a slight modification to work on an MKI swingarm.

 

Bad news is they are powder coated red.

 

Caliper was rebuilt when powder coated.

Pictures attached.

 

Gary

[Venturous Randy]

Bad news is they are powder coated red.

 

Caliper was rebuilt when powder coated.

 

 

 

Gary

 

Hey Dingy, are you ever going to run out of red powder paint?

RandyA

[dingy]

Hey Dingy, are you ever going to run out of red powder paint?

RandyA

 

Actually, some of the previous red was turned to black today.

 

I stripped lower fork tubes and did them in gloss black. Also finally got a ventureline radiator cover that I got from Bongo a couple of years ago coated black today.

 

Front rim will be gloss black, it came from a VMax. Rotors are a satin black from an FJR that are going on.

 

Next to last is what it looked like in fall, last one is what it looks like tonight.

 

Plan is to paint it bright yellow & get it pin stripped at MD in Oberlin. The red accent items were planned for the yellow all along.

 

And, no, I just got a pound of super mirror red, for those little touch up items.

 

 

Gary

[barend]

Could barely get the bike out of the garage to go to work last night so I left it and took the truck. I did pull the caliper again and measured the disk, it appears to be the correct thickness.

 

I can not find any writing on the disk other then the numbers 2081 on both sides.

 

I did take some pictures but I've been up since 1500hrs and I need to get to sleep, I have another ten hour shift tonight.

 

I did re-install the caliper without the obvious non OEM "spacers" to see what would happen. It appears the inside piston compresses all the way while the outside still appears to be slanting. could not turn the wheel by hand like that.

 

I did a very rough check for warping by holding a reed up the the outside of the disk and spinning the wheel (without caliper), I did not observe any type of oscilation.

 

May take you up on that caliper and swing arm if I can't figure this out Dingy. I'm sure a rattle can of black paint will take care of any red.

 

If y'all think of anyting else i can check let me know, I'm gonna crash!

[barend]

I did some measuring: from the bracket face to the center of the disk is 37.35mm

from the outside of the caliper mounting tab to the center of the pad cavity is 29.37mm

 

I took the pads back out and compressed the pistons all the way and I can not mount the caliper centered without spacers between it and the bracket. The wheel would have to come over to the right to do so! I wondered if the bracket could be bend somehow, but then figured it was a cast piece and wold break first.

Then a scary thought occurred, first time I was trying to set up the sidecar I noticed that the right outside of the rear tire is almost in line with the right outside of the front tire. I contributed it to maybe a warped frame since I could not find evidence of a cracked frame. I noticed the same thing after modifying my sidecar sub frame and having to set it up again. Is it conceivable that when the disk was replaced by me (shop), the wheel was re-installed wrong (again) causing the need for spacers. Could this somehow be related?

[dingy]

I did some measuring: from the bracket face to the center of the disk is 37.35mm

from the outside of the caliper mounting tab to the center of the pad cavity is 29.37mm

 

I took the pads back out and compressed the pistons all the way and I can not mount the caliper centered without spacers between it and the bracket. The wheel would have to come over to the right to do so! I wondered if the bracket could be bend somehow, but then figured it was a cast piece and wold break first.

Then a scary thought occurred, first time I was trying to set up the sidecar I noticed that the right outside of the rear tire is almost in line with the right outside of the front tire. I contributed it to maybe a warped frame since I could not find evidence of a cracked frame. I noticed the same thing after modifying my sidecar sub frame and having to set it up again. Is it conceivable that when the disk was replaced by me (shop), the wheel was re-installed wrong (again) causing the need for spacers. Could this somehow be related?

 

 

Does the caliper bracket/swing arm have the spacer washer installed. 1st picture is of an RSV, but similar.

 

On yours it will look a little more like the 2nd picture, but this is an MKII setup. Thick washer is between the black swing arm and the red caliper arm.

 

If this spacer is missing & you have the thinner rotor mentioned above, this could be causing the mis-alignment issue you are having.

 

Gary

[barend]

There is a space in between the bracket and swingarm, looks to be 3mm. What i can not determine if it is a shoulder on the bracket or a spacer. (I know, pictures would help, unfortunately my digital camera is broke and my phone won't send the pics to my e-mail for some reason).

 

Could I drop the wheel with it sitting on the center stand to see what kind of spacers I've got where? I.e. not totally remove it which for me would requiring the removal of he front wheel as well and kneeling it.

[dingy]

There is a space in between the bracket and swingarm, looks to be 3mm. What i can not determine if it is a shoulder on the bracket or a spacer. (I know, pictures would help, unfortunately my digital camera is broke and my phone won't send the pics to my e-mail for some reason).

 

Could I drop the wheel with it sitting on the center stand to see what kind of spacers I've got where? I.e. not totally remove it which for me would requiring the removal of he front wheel as well and kneeling it.

 

I really don't know what you are able to do with a sidecar attached.

 

If it is on the center stand, normally the rear wheel is off the ground.

 

3mm sounds about right for the width of the spacer, that's close to 1/8".

 

Gary

[dingy]

Attached are a couple of pictures of an 83 caliper arm.

 

Maybe this will help you determine what your spacer situation is.

 

Gary

[barend]

Thanks Gary! Yes there is a spacer in there then. Talked to Earl and he is going to send me a rebuild rear caliper since the one I have seems to be sticking. He also posited that someone may have put a front caliper on the back, says there is a slight difference in the offset. I'll wait to see till I get that thing before I start doing anything else drastic.

 

Btw: three bolts, ten minutes to remove the sidecar :-)

[jasonm.]

did anyone answer the spacer question. I can only tell you that my '87 has from left to right--- on the right side of the wheel a spacer against the wheel bearing that sits within the seal, then the caliper holder...then washer(often lost) to protect the aluminum caliper bracket from the "stepped" axle. Note: there is a hardened washer under the nut on the left. So technically there is only ONE Spacer. Everything else are washers. ALSO, I don't have any spacers or washer between the swingarm and the caliper bracket. Had this bike for 95% of it's life...never seen anything on the swingarm

Edited February 24, 2012 by jasonm.

[dingy]

did anyone answer the spacer question. I can only tell you that my '87 has from left to right--- on the right side of the wheel a spacer against the wheel bearing that sits within the seal, then the caliper holder...then washer(often lost) to protect the caliper bracket from the "stepped" axle. Note: there is a hardened washer under the nut on the left. So technically there is only ONE Spacer. Evrything else are washers.

 

See post #11,13 & 14

 

I think it was answered, just took a while to get it all out.

 

Gary