I am in over my head with radials installation

[mundmc]

Hi all, hope everybody’s safe,
It’s been a while. I finally tried to put my 18” wheels on that I purchased from a forum member some rime back. Per him, they came off a vmax. The rear is an Avon Am23 180/55.

The first big problem- the tire hits the drive shaft. The second big problem- the rear brake calipers don’t really fit without putting a lot of pressure on the disc.

Any thoughts on where to start here??? I’ve read up a bit, but I know just little enough to go down a very wrong path.

My thanks in advance
Mun

 

[Fire-medic]

You can try re-positioning the rear axle washer to get a bit-more tire clearance.

https://www.vmaxforum.net/threads/rear-wheel-axle-washer-swap-fit-wider-tires.35953/

You need how-much clearance on the tire? Do the washer swap first, and see how-much (if-any) additional room you need. If it's just-barely 'kissing' the driveshaft, at a narrow point of contact, perhaps a touch of sanding of the tire will clearance it sufficiently. I'm not telling you to sand an inch-wide band, down-to the tire cords. Probably a better choice is to mark where the interference is, and to determine how-much space you need-to gain. A bit of heat and some persuasion with a ball pein hammer (yes, you're going to have to repaint the swingarm where you heated it) should gain you whatever space you need.

I think most people on-here who have gone to an 18" rear wheel/tire haven't had that issue. I have a machinist make 5-1/2" X 18" rear wheels to use the stock splined hub, and I haven't had an interference problem with 170 or 180 mm width-tires, in a 55-series aspect-ratio. How-wide is your rim inside the tire flanges? If it's 6" I suspect you will have an interference without clearancing your driveshaft/swingarm.

About your rear caliper, you have an opposed-piston caliper, one of them. I think your post is just a typo: "...my calipers...". You may have a sticking piston or pistons, probably due-to corrosion on the caliper body and the pistons. The pistons should never be 'tight' on the rotor, unless you have pedal pressure on them. Probably time for a disassembly and cleaning of the rear caliper, a flush of the rear master cylinder, brake line, and caliper, and replacement onto the bike.

I am considering another possibility. You may-have put pressure on the rear brake pedal, while the caliper was off the rotor, and now the pistons are too-far together. You need-to push them apart, so the caliper can easily slip-into place. Then you tighten the bolts and the axle nut, and pump the rear brake pedal a few times to move the pushed-out pistons inwards towards the brake rotor. If you don't, the first time that you try to-use the rear brake pedal, it will bottom-out against the stop, with no braking, and if you don't have time to pump the rear brake pedal enough to restore your pistons to being just-off your rotor, no brakes!

I recommend doing a 'reverse-bleed' for your rear brake. It's much-quicker, and more-effective for removing any air in your brake system. You can use the same technique on both f & r brakes, and the hydraulic clutch. No-need to tie-wrap any lever (clutch, brake) or pedal (rear brake) in the hopes that air bubbles will rise-to the master cylinder, because you won't have any bubbles in either the f & r brakes or the hydraulic clutch, if you properly-perform the reverse-bleed.

https://www.vmaxforum.net/threads/reverse-bleeding-clutch.47305/#post-472105

 

[mundmc]

John Furber popularized re-positioning the rear axle washer to get a bit-more tire clearance.

Hey Fire Medic, long time!

I know of the “Furber fix,” I’ll look into the rear axel washer- i THINK i know the washer you are talking about, and I have seen this referenced on the boards.

 

[mundmc]

Whoah i only saw a little bit of your original response- thanks for the thoughtful post! Fun fact- you referred me to the seller in July of 2017!

Just to be clear- I think I move the washer from (between the caliper bracket and the swing arm) to (between the, uh, wheel hub and final drive housing)? Can you tell I’m new at this?

 

[[email protected]]

Yes, put washer between splines on wheel and differential

 

[mundmc]

Yes, put washer between splines on wheel and differential

Awesome, thanks so much!

 

[Itgoes]

Checked our your post and just realized you purchased those wheels from me. After much searching I found some photos that show the wheel on the bike. I hope they help! It looks like maybe there is only one thin washer used on the right side. there is not a real clear shot of the left side unfortunately.




Good luck!

 

[mundmc]

Hey! Thanks so much for these! I had no doubt this was working out at some point, and you included extra washers which i already put to use on the front wheel.

Interestingly enough, it looks like the swappable-washer is in the stock position here. I’ll report back in after swapping it.

 

[mundmc]

Checked our your post and just realized you purchased those wheels from me. After much searching I found some photos that show the wheel on the bike. I hope they help! It looks like maybe there is only one thin washer used on the right side. there is not a real clear shot of the left side unfortunately.


View attachment 71076 View attachment 71077 View attachment 71078 View attachment 71079

Good luck!

The washer swap totally worked to make the wheel fit! Now I notice the disc is much bigger than the stock disk, and using my stock break mounting arm the disc presses into the break caliper so hard it will not turn. I know you parted that guy out over 2 3/4 years ago, but any idea what kind of modifications I might need to do to make the big disc on this wheel fit my current rear brake caliper mounting hardware? Everything in those pics looks stock except for the disc and wheel, so I'm confused.

@Fire-medic, I pried the brake pads apart and they fit over the disc; it helps that the new disc is ~5mm whereas the stock disc is ~7mm. I will clean and bleed the rear brake regardless, but I think the problem is more related to the size of the disc than it is to the calipers or seating of the wheel at present.

 

[Itgoes]

The washer swap totally worked to make the wheel fit! Now I notice the disc is much bigger than the stock disk, and using my stock break mounting arm the disc presses into the break caliper so hard it will not turn. I know you parted that guy out over 2 3/4 years ago, but any idea what kind of modifications I might need to do to make the big disc on this wheel fit my current rear brake caliper mounting hardware? Everything in those pics looks stock except for the disc and wheel, so I'm confused.

@Fire-medic, I pried the brake pads apart and they fit over the disc; it helps that the new disc is ~5mm whereas the stock disc is ~7mm. I will clean and bleed the rear brake regardless, but I think the problem is more related to the size of the disc than it is to the calipers or seating of the wheel at present.

Hmmmm......as far as I know those brakes are stock 1985 pieces. The calipers definitely are I believe, I still have them.

Here are a couple more photos, I hope they help!

 

[mundmc]

I am wondering if they did something with the brake mount arm, hmmmmm. Thanks for your thoughts

 

[mundmc]

For perpetuity, almost a year has passed, and all I needed to do was give the caliper halves a little gentle persuasion with an angle grinder. Now to replace the pads and see if if this works...

 

[Fire-medic]

Wow, I think I would have looked for a smaller diameter disc that fit the caliper w/o the grinding. Do you have a shot of the caliper mounting bracket, before you tried to fit the wheel?

I suppose that would work, what you did but I would be interested to see the bracket.

 

[mundmc]

Thanks as always for your interest Fire-medic
I ran into difficulty as the rotor on the new wheel uses a different bolting pattern i would have to identify (which i still plan to do, probably upgrading the caliper in the process), but for some reason this was more daunting to me crudely milling some hopefully less important aluminum.


Basically, I really miss riding my Vmax, it has been over a year. I had a disagreement with my tablesaw while I was working on this project a year ago, and it kind of set me back.
Oh, and here’s the caliper arm mount:

 

[Fire-medic]

Oh geez, makes you wish you had a SawStop, huh? But apparently you saved the finger, no amputation. I have two Powermatics, a 64 and a 66, they can and will divest you of body parts in a moment of carelessness or inattention. What's the dia of the new wheel's rotor vs OEM?

 

[desert_max]

Ouch. Remind me never to disagree with a table saw!

 

[mundmc]

Lol, that xray is deceiving; my distal phalanx was hanging by a shred of tissue, but luckily that shred kept it perfused. They made me go to a level 1 trauma hospital because it was an “almost complete amputation.”

I chose an ac tig welder over a sawstop in a very difficult decision

i have to get back to you on the dia of the rotor on the new wheel

 

[Fire-medic]

I used to take the paramedic students to a couple Level 1 trauma facilities for their clinicals, and it was the best place to go for experience. We would have to ask for permission for each case, to be allowed to observe, and my advice was, "get gowned and stay out of the way, and answer the MD's questions about what you have studied and/or done, if they can, they will put you to-work." And they did.

You're lucky. I had a firefighter/paramedic friend who had his hand grafted to his body to save his hand, after a bike accident.

Those rotors look pretty-close in size.

 

[one2dmax]

We have an offset bracket to allow the stock caliper to fit on a 298mm rotor (stock rear is 280mm). Saves having to grind

 

[mundmc]

We have an offset bracket to allow the stock caliper to fit on a 298mm rotor (stock rear is 280mm). Saves having to grind

Doh! Knew i should have asked around more!