shaking front end

[poorboy112597]

I have been experiencing a shaking front end everytime I break the last couple of months. Randy told me to make sure there wasn't any brake fluid on my rotors because it may cause this, I cleaned them and it seemed okay at first. I was sure that was it becaue i had change the fluid not too long ago. Didn't really have time to go for a long ride that day, just around the parking lot.
Took the bike out the other day and the same thing. No brake fluid leaks, but still shaking. Anyone have any idea what it could be? I suspect it might be the steering bearings but not sure, if so is it hard to do myself? Can't afford dealer repairs. Thanks in advance

[Geezer]

It sounds like you have a warped rotor.

Geezer

[poorboy112597]

It only happens when i brake, mostly at higher speeds. Thanks for responding... scared because thought they dont have rotors anymore for these bikes

[Geezer]

You can have them resurfaced and that will even them out. However it can be difficult to find a place that will turn stainless steel rotors.

Geezer

[poorboy112597]

I asked a dealer that the other day and he said he never heard of resurfacing bike rotors... Do you know any place that will do it through mail other than merrimac?, I think they are way over priced on everything

[Pat Kelly]

Possibly a warped rotor? Does the brake lever 'pulse' in your hand? Make sure all the bolts on the front end are correctly tightened, fork bolts, caliper bolts, axle nut(s), etc.
You could also check that front and back wheel are aligned with each other.
I made an alignment board for my 78 Honda. I divided the measured width of both tires in half and cut a board the I would place along both tires ten adjust drivechain tension and alignment. Using this method uncovered mismarking in the notches on the swingarm, they were off-set by one.
Anyhow, this would assure front and rear wheel alignment.

[Bubba1954]

I think that Tony is right.

The shaking or pulsating you describe is most often caused by a warped brake rotor. On a bike, rotors get warped usually due to a caliper that fails to release presure from the disc causing friction heat to build up enough to warp it. It is easy to test for a warped disc.

First place the bike on the center stand, mount a small jack under the frame to raise the front end high enough for the front wheel to turn freely, which it should. If it does not turn freely, and drags more then just slightly, you likely have a caliper piston that is sticky and is failing to return to it's recesed position when the brake is not in use. May need to rebuild the caliper.

Next mount a dial gauge to each side fork tube or something similar, then turn the wheel by hand to see if ether rotor disc is warped. If it is, you need to look for another rotor.

You can often find good used rotors out on ebay. In fact I seen a set of all three listed there last night. They were recently listed and only going for $10 each as I recall.

[poorboy112597]

Now your talking, thanks for the advice i'll try everything you guys suggested. If not gonna place a bid for the rotors on ebay

[poorboy112597]

i'm on parts n more's website, there are a couple caliper rebuild sets that look like they would work for my bike, 1980 xs special. One is for $14.00 and the other for $16.00, the $16.00 one looks like it has more parts...Which do you think is the right one bubba?

[Winterhawk]

If you have access to a lath, put it in there, turn it while taking a belt sander to them untill smoth. Then some emery cloth on a piston pin. For some luster hit it with steel wool while turning also. If not send them to Merriam cycle . Don't know how much but might be cheeper than new.

[poorboy112597]

i really am trying to avoid sending anything to merriam, they seem so pricey. I might know somebody with a lathe that i could ask for a favor though. thanks for the idea

[Jerry]

Turning/resurfacing rotors has come up before....not a real valid option.

A machine shop with a surface grinder can take out minor imperfections. However, the tolerance on the rotors is so small that most shops won't touch them; the end result is a rotor thinner than spec. Liability, you know.



Your best bet is to find used rotors in good shape. The XS/XJ front rotors are interchangeable, though the slotted style of the '81 and XJ are directional and stamped L or R. Some model 750s (Seca) of the same age used the same rotors. New units are available from Brembo and others for around $200 apiece.

Do a search on rotors or brake rotors to find past threads on this topic.

[poorboy112597]

Thank Jerry,
Seems like my only option is going to be to cough up aproximately $200.00 per rotor. I thought about the used rotors, but how do i know they haven't exceeded spec without measuring them myself. Hope the rotors are the issue and not something else. I might try rebuilding the calipers first, a cheaper alternative it seems.

[Winterhawk]

If you buy new rotors get the high performance once that are a full floater. I've had lots of good luck sanding rotors while spinning them in a lathe. An auto parts store cuts them and they will trash it. Most shops are not up on how fix them anyway. They just wanna sell you new ones.

I like these rotos here I think they are about $200.00 but not sure.

[Bubba1954]

I went to the PartsNMore website and looked and it apears that this is the rebuidl kit and piston needed to rebuild ether front caliper on your 1980 Special. I have never used any parts from this vendor before so I cannot atest to the quality of them. Perhaps other members have used their parts and can recomment them. As hard as some of these parts are getting to find these days, sometimes a person has to take what is redily availible.

http://66.51.166.223/PNMSite/XS750-8...iper%20Kit.htm

http://66.51.166.223/PNMSite/XS400%2...r%20piston.htm

I would find out if ether of your two rotors are actually warped and deturmine the condition of the calipers before spending any money on parts though.