motorcycle mechanical advice please?

Question

i am getting a major shuddering from front end when applying front brake the harder brake is applied the more severe shuddering is. have an idea what the problem is. brake disc is ok brake pads ok. any help/advice much appreciated.

other possible defect have a leaky shock absorber/fork leg on right side.

could this cause an inbalance in front forks resulting in shudder

it is major vibration /shudder felt thru handle bars feels as if wheel is skipping/locking for a split second but as shock on one side is knackered this could put a lot of unnessacary stress on one remaing shock as one will travel and other will function normally causing instability wen braking. is not head race as this was replaced within last few weeks. am starting to go with a combination of brake disc being warped and dodgy shock on fork.

BUT HAVE DECIDED IN THE INTERESTS OF SAFETY BIKE WILL BE OFF ROAD UNTIL SUCH TIME AS BIKE HAS BEEN CHECKED BY A MECHANIC AND PROBLEM RECTIFIED.

THANKS FOR ALL YOUR HELP.

BIKE SAFE

Answer 1

Hi,
Sounds to me like your headrace bearing are loose or worn out.
Get it to a motorcycle shop or to someone who knows what there doing and get it sorted,its not that safe to use in that condition.
GOOD LUCK.

Answer 2

Always give year, make, engine size and model # when asking questions. We need all of that info to give an informed answer. The year and mileage of your vehicle would've been helpful. Also, someone with the same bike as yours, may have had the same problem and would know the repair procedure.
--Unless the brake disc had visible damadge, you wouldn't get a severe shuddering. You'd get a pulsing feel from the brake lever.
--Depending on what bike you have, conventional forks (not cartrage) have internal bushings that can wear out. They should be changed whenever the fork seals are changed (they're inexpensive). Here's a picture of them.
http://www.mrcycles.com/
Go to - Honda - 2000 - CB750 - Front Fork - #7 & #8
Zoom In for a better view.
--Check the front tire. A "cupped" tread pattern may cause this. Make sure the tire pressure is correct.

--Check the steering head bearings.
--Put your bike on the center stand (if it has one) or jack up the bike so the front wheel is off the ground.
--Pull the front wheel forward, away from the bike. If the steering bearings are loose, you'll feel it.

Answer 3

First deal with the leaking fork. Having them resealed is fairly painless. While they are out take apart the steering head and check the bearing for proper lubrication. If the bearings are still in good shape repack them and follow torque procedures. While everything still apart check the pads and rotors. Since it is easier to repair the leak with the front disassembled carefully inspect every other component. Upon reassembly you will have serviced/repaired anything wrong with the front end. If you can't do the work it might cost a bit however a lot cheaper then an accident.

Answer 4

Yes the oil leak could cause it to shake a little but not that savre.
I would be lookin at wear to the lower stansions, if you get the front end in the air and get some one to sit on the bike with the back break on. get hold of the lower forks by the spidle then pull and bush, you will probably find that there is movement, if there is it will prob be the bushes need replacing, some bikes you need to change the stansion. or you may find that movement is coming from the headstock bearings but unlikely as this normally causes the front end to knock when your breaking.
or wheel bearings could be shot. my bets its the shoks.

Answer 5

Could be a few different things. . . if you feel the brake lever pulsating when you apply the brake, the rotor is most definitely warped. ( you will not likely be able to see that the rotor is warped as it does not take much more than a few thousandths of an inch to cause pulsating) If you feel it in the handlebars and no lever pulsing it could be your front wheel bearings, worn front shocks, bad front tire, bad steering head bearing, or the rotor could have uneven "sticky" deposits left behind by overheated brake pads (this causes the friction between the pad and rotor to change as it spins.)

Answer 6

Even if your front brake looks ok you might have a minor warp in it from heavy braking. If you are not getting the shudder at high speeds without the brake and you are sure your shocks are in good condition, a trip to the mechanic might be in order.

Answer 7

A simple series of tests with a volt meter will give you some insight into whether your problem lies with your battery, your alternator (yes, your bike does have one) or elsewhere. Charge the battery and let it stand for an hour. Voltage across the terminals should be 12.6-12.6 v. Crank the starter. If the voltage drops below 10 v the battery is probably bad. Charging voltage at idle should be in the neighborhood of 13.1 v. If it remains at the resting figure or below, your alternator is not putting out. As you increase the revs, voltage should rise to 14-14.5 v. before the regulator shunts current to ground and voltage levels out or falls off. If the battery and alternator check out, it is time to start looking elsewhere.

Answer 8

It will be the brake disc distorted. It may appear to be in good order but if you were to check the run out with a dial gauge, you will find that it is not true.

Answer 9

check calliper bolts are tight,
check front wheel is tight- - also that wheel bearings OK, hold side of wheel top & bottom push & pull back & forth should be no movement.
check head stock bearings - - & nuts,
put bike on centre stand put box or jack under engine to lift front wheel or get someone to hold back end down while you pull & push front wheel back & forth any play head stock loose or bearings buggerd,

Answer 10

Check the head race adjustment. Have you noticed any wobble at certain speeds without applying the front break?