Topic: Front Brake Lever not Returning

[shinysideup]

front brake lever stays half way- seems to stop ok, but brake light stays on.
is there a way to replace the return spring?

78 cb750F

[Raul CB750K1]

Does your bike have a mechanical switch or a pressure switch like the former CB750's? If so, then there is pressure on the circuit and changing the spring won't fix the brake; probably you have a bad return valve. Time to rebuild the master cylinder.


Raul

[TwoTired]

front brake lever stays half way- seems to stop ok, but brake light stays on.
is there a way to replace the return spring?

78 cb750F

Yes, there is a return sping inside the master.  However, the bore is likely choked with hardened brake fluid that blocks the piston return.

Rebuild and hone the master cylinder bore.

The hydraulic system is resupplied with fluid from the reservoir when the piston returns all the way.  If it isn't then the lever will get progressively ineffective as the pads wear.  Eventually, the lever will hit the grip before getting any stopping power.

Cheers,

[mick750F]

front brake lever stays half way- seems to stop ok, but brake light stays on.
is there a way to replace the return spring?

78 cb750F

   Sounds like it's time for a rebuild of the master cylinder. Your symptoms are exactly what mine were before I did my rebuild. The kits are available from Honda.

Mike

[MRieck]

 I'd rebuild the calipers and flush the lines too.

[mick750F]

I'd rebuild the calipers and flush the lines too.

   Agreed.

Mike

[BobbyR]

Best flush for the brake system is denatured alchol from Home Depot or where ever. It is what evaporates out of the fluid and leaves the crud behind. That is why brake fluid eats paint. 

[dusterdude]

should we start the dot 3 versus dot 5 debate again?

[wardmoto]

make sure you have the snap ring pliers from satan's own garage from hell and make the wife and kids leave before you attempt.  If you are not concerned with originallity, sell the bastard on ebay and get yourself a modern m/c.  Honda uses the same stuff on different bikes for a while...I used a late 90's CBR 600m/c in awesome condition I got for 40$.

[shinysideup]

If you are not concerned with originallity, sell the bastard on ebay and get yourself a modern m/c. Honda uses the same stuff on different bikes for a while...I used a late 90's CBR 600m/c in awesome condition I got for 40$.

you make a good point... I'll have to consider that for sure.
1) how do i make sure the two will interchange?
2) isn't bleeding the system with twin calipers a major pain?
3) anyone want to buy a lightly used bike?

thanks for the thoughts.

by the way- I'll all for the best brake fluid i can buy- if i'm gonna take the time to flush the system, why would i try to save the three dollars difference in fluids? that's like putting a starter from murray's in my car....

[MRieck]

should we start the dot 3 versus dot 5 debate again?

What about DOT 4???

[dusterdude]

yea,that too.

[mick750F]

   Can we include the often ignored 5.1 this time?

Mike

[wardmoto]

I put that CBR m/c on 7/8inch clip ons and had no problems...I don't know what the diameter on the stock bars on your scoot would be

[MRieck]

   Can we include the often ignored 5.1 this time?

Mike

Good stuff the 5.1.