front brake drag

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yamahoper
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Location: Huntington Beach ca

front brake drag

#1 Post by yamahoper » Thu Mar 09, 2017 8:15 pm

Bought my first RZ500 I've had it 2 weeks. Overall the bike looks to have been through a lot of neglect. The fork seals were leaking all over the brakes that had lots of air and a jelly like substance instead of brake fluid. I flushed the brake lines with fresh dot 4 fluid and blew them out with compressed air till clean. Changed out the pads for some EBC HH. Put some miles on her yesterday and noticed at a red light how much rolling resistance the bike had... I pulled the front calipers and gave the tire a spin and it was good, about 10 revolutions. Put the left brake caliper back on and spun it, got about 1 1/2 revolutions. Put the right on and less than 1 revolution from a good hard spin. this was before I applied any brake lever after replacing the calipers. I applied the brakes several times while spinning the tire and the brakes are working well. There is no change in free wheel spin still about 1 turn. Any Ideas or is this normal?

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tacky1
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Re: front brake drag

#2 Post by tacky1 » Thu Mar 09, 2017 8:20 pm

Its either a warped rotor or the calipers need to be stripped and cleaned, They are notorious for sticking, Take them off and remove the seals and pistons and clean them all up, A lot of gunk usually builds up in and around the dust and fluid seals and that keeps pressure on the pistons which in turn keeps pressure on the pads..
1985 RZv500
1984 RZ500 Hybrid
1986 RG500 Walter Wolf
1986 RG500 Skoal Bandit
1984 RZ350
1984 RZ350 Hybrid
1981 RD350LC
1981 RD350LC Hybrid
2009 CR500AF Supermoto 250X
2007 CR500AF 250X
1988 YSR50 (2)
1989 VFR750R RC30
1984 GPZ750 Turbo

yamahoper
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Location: Huntington Beach ca

Re: front brake drag

#3 Post by yamahoper » Thu Mar 09, 2017 8:26 pm

Just for a comparison I checked my modern Yamaha = about 6 revolutions Then my 1975 H2 with single disc 3 revs

yamahoper
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Re: front brake drag

#4 Post by yamahoper » Thu Mar 09, 2017 8:58 pm

Just went and checked the neighbors rz350 =about 2 1/2 revs

silverstrom
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Re: front brake drag

#5 Post by silverstrom » Thu Mar 09, 2017 9:54 pm

Could also be the master cylinder. If it sticks it won't release pressure. Try the same test but give the mater cylinder a few whacks and see if it helps. If it does, you've found your problem. Rebuild kits are available.

Before completely disassembling the calipers there is one more option. Remove the pads. Then use a clamp to hold one piston in place. Use the brake lever to pump the other piston out past it's normal position with pads. Clean the piston well with brake cleaner. Press that piston back into its bore and do the same with the other piston. Dirt and grime accumulate on the piston and prevent it from going back in its bore when the lever is released. Often, all that's needed is a cleaning as I've described, without the need for a full caliper tear down. It helps if you have the proper tool to compress the piston. Available at any automotive shop for less than $10, typically.

If it isn't the master cylinder and cleaning the pistons doesn't work, or the piston surface is corroded, then do as Tacky says and strip the calipers. At that point you need to do a full rebuild.

Welcome to the joys of vintage ownership and previous owners neglect.

yamahoper
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Location: Huntington Beach ca

Re: front brake drag

#6 Post by yamahoper » Fri Mar 10, 2017 12:37 pm

Good stuff, thanks guys! The to do list seems to be getting longer instead of shorter. The add said great bike needs battery and probably carbs cleaned

gpaddict
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Re: front brake drag

#7 Post by gpaddict » Fri Mar 10, 2017 8:11 pm

Let's see this beast

yamahoper
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Re: front brake drag

#8 Post by yamahoper » Fri Mar 10, 2017 11:02 pm

rz500resize.jpg
rz500resize.jpg (194.53 KiB) Viewed 3856 times
This is how it looked when I received it, nice petrified 25 year old tires

BigGuy
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Re: front brake drag

#9 Post by BigGuy » Sat Mar 11, 2017 10:09 am

Note the unmolested rear mud guard! LOL. Quick, someone get a blindfold and a sawzall and get that sucker!

Looks like a good place to start, it's all there. Welcome to the club.
Shake "N" Bake!

yamahoper
Posts: 38
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Location: Huntington Beach ca

Re: front brake drag

#10 Post by yamahoper » Sat Mar 11, 2017 6:02 pm

This is 2 weeks later and 60hrs of maintenance
KIMG0633r.jpg
KIMG0633r.jpg (229.21 KiB) Viewed 3816 times

silverstrom
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Re: front brake drag

#11 Post by silverstrom » Sat Mar 11, 2017 8:22 pm

You painted the wheels?

yamahoper
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Location: Huntington Beach ca

Re: front brake drag

#12 Post by yamahoper » Sat Mar 11, 2017 10:16 pm

silverstrom wrote:You painted the wheels?
No, A spare set of painted rims came with the bike. Thought I would go with them on the first set of tires.

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Re: front brake drag

#13 Post by silverstrom » Sun Mar 12, 2017 12:25 am

That's good. I thought maybe you had repainted the stock gold wheels, and since your bike appears all stock other than the front signals having the gold wheels is definitely a plus.

I think I see where you're going with it; the black wheels, new pipes...what comes after that Rob?

Will you be replacing the cheap front signals? That's me being not so subtle. Lol

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wolfgangh
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Re: front brake drag

#14 Post by wolfgangh » Fri Jul 22, 2022 5:15 pm

Hi, I want to jump on this old thread. I currently do a full restore on a low-mileage 47x RD500, and I disassembled also the brake calipers and gave them a good clean of bore and pistons, plus new EBC pads. After installing them back on the fork, I noticed an enormous drag. Removed the calipers, and the drag was gone. So I took another set of good calipers from my spare parts box, did again a good clean/polish of bore and pistons, replaced all seals with YAMBITS, and checked the pistons for easy gliding before assembly. Put in the same EBC pads that I had used before in the other set of calipers, and got the same drag. After closer inspection, I notice it is the inner pads that press on the disk when the calipers are mounted, as if the were too thick. The piston seems to be already fully in, but the pads still have strong contact with the disk. I could now either put some 1mm shims between fork and calipers, or use a thinner brake pad.
Did any of you have similar issues with EBC pads, are they simply too thick?

V4 Stroker
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Re: front brake drag

#15 Post by V4 Stroker » Sat Jul 23, 2022 4:06 am

wolfgangh wrote: Fri Jul 22, 2022 5:15 pm
Did any of you have similar issues with EBC pads, are they simply too thick?
No issue with EBC HH pads on my front OEM calipers and pads

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