front wheel woes

Hi folks,

Need help here, please. A 1981 750 Seca (650 cycle parts though) that I got for nothing, running but neglected. It was left outdoors for a few years, completely exposed. I have had it out on the road, just for a quick test. I'm doing everything for the first time, and it's my first bike.

I just changed the front tyre.

Reassembling the wheel from memory, and now it's not spinning at all. I greased the speedo gearbox, and between it and the left fork is a spacer yes ? On the other side is a wider spacer of two diameters butting against the seal, and inside the right fork. Outside the right fork, a castle nut and spring washer. Does this sound right ? Not finding Haynes very clear.

Second - the brake assembly was in a terrible state, with the pistons red rusty and almost seized, seals completely perished.. I presume those are grease nipples on the casing above the piston ? If so, they weren't used in a very long time. Can I renew the piston assembly ? Can I immerse it in diesel or something, or are there seals inside that would be ruined ? How to proceed ?

The brake WAS definitely working though. Having put the wheel back on, there is now little or now pressure in the brake lever. I did not touch the hydraulic system. It seems to be a little better now, but why has this happened ?

I merely cleaned the pads and their shims, and put them back on so that they cleared the disc. Was that sufficient ?

As ever, thanks in advance, and thanks for a really great forum - I'm learning huge amounts.

 

Did you overtorque the castle nut?

Are you SURE the brakes aren't grabbing the rotor? That would be my first guess.

If you do some searches, you will find out that these bikes have occasionally locked up the brakes due to age.

You can take the wheel back off and test the bearings by sticking your finger in there and seeing if the inner race turns. If that works, then the above things I mentioned would be your best bet. I guess someone could have reassembled the bearing wrong? If I am correct, I think the inner races can come out. So maybe they were put in backwards? I don't know what difference that would make.

 

Most common mistake is to tighten the pinch bolt so it holds the axel while you tighten the castle nut. Result: Pinc bolt holds the fork leg and as the castle nut is tightened the forks bend in together. Axel is now in a bind and won't turn. Richard is SOOO right about checking the brakes. Sometimes the pads slip and a rotor is caught against the brake caliper. Another source is the speedo gear. Look at it closely and you will see thatit engages the gear dog with 2 prongs. Make sure these line up with the gear dog that is inside the rim.

Hey Richard, nice avatar, do we call you Raphael now!

 

They ARE NOT grease nipples ... they are brake fluid BLEED nipples. If the caliper is stuck ... the pads will drag on the rotor and the wheel wont spin.

Try removing the brake pads and see if it rotates. If not ... you might have to replace wheel bearings ... easily done ... the size is a world standard not needing Yamaha Genuine ... I gor a new PAIR for my bike for less than 20-bucks. The bearing size is engraved on the race... call bearing suppliers and get the best price for new sealed bearings.

 

Bearing size is a 6302RS.

 

You may wish to visit the Yamaha web site and take advantage of their archives of microfisch illustrations. They are free (Thanks to the good Lord, somebody got smart here) and will show the exact parts placement and order. BikeBandit.com has the same info but poorer resolution. Good luck!

 

Thanks as ever guys. Plenty to think about when I get home from work. I didn't know about those microfiche.

Anyone got any thoughts on renovation of the brake assembly ? Definitely needs doing, whatever else happens.

Regards,

Yep

 

I loved the ninja turtles as a kid!

Be sure and try Bluemaxim's suggestion about the pinch bolt before spending anything!

 

Sorry guys, scrap the question about renewing the caliper - was so fed-up fatigued yesterday just didn't see it in the manual. I think I have all the info I need... famous last words.