Front Brakes

[Tex]

Hi all,

  Took the FJ on her first long trip. Went into Mass to Mt Greylock. About 300 miles there and back. She ran great. The next day went to take her out and the front brake went right down to the grip. Pumped her a couple of times and they worked. What would cause this? 


Scott

[Capn Ron]

Sounds like a nice ride...New England has a lot to offer in the way of scenery (especially this time of year!!) and nice roads!

If you're saying that the lever dropped right to the bar and you had to pump it up to get any sort of feel...then you've got air in the system.

It sounds more like you are saying that the lever dropped right to the bar and a couple of pumps of the lever just fixed that issue for the whole day, then that's a different beast.

I'd start with the master cylinder.  Got plenty of brake fluid showing in the sight glass?  When is the last time that was rebuilt or replaced?  Could have a hinky seal in there.

You've got a slew of lines heading all the way back to the ABS pump and of course the ABS pump itself...and more lines going back up front for that all to work.  Even if the ABS pump/system fails, the system should act just like a non-ABS brake system.  I'd be focusing on that master cylinder.

Cap'n Ron. . .

[Tex]

   Yes the lever went right down to the bar.  A couple of pumps seemed to fix her. But again today she felt soft again. Not all the way down but soft. Again pumped her and she seemed better. I bleed the system twice already when I first got her 2 months ago. As for the master cylinder it probably has never been rebuilt. The front breaks have never felt like the way I think they should feel.

   So if the seal in the master is no good this would cause these issues? Does RPM carry rebuild kits?


   For the ride yes it was beautiful. My girlfriend and I really enjoyed it. It's nice to be on a bike that's handles so well and has no issues with two up.  Mt Greylock is the highest Mt in Mass. The view was amazing and the ride up to the top was fantastic.

[Capn Ron]

Yes, Randy has the rebuild kits...

Do yourself a favor and bookmark the following in your favorite browser:

http://rpmracingca.com/products.asp?cat=39

On that page, you can just type in a keyword like "master" or "brake" and click the go button.  That'll get you right to the parts you're looking for.

So, to my way of thinking, if there is a specific amount of air in the brake lines, the lever will always feel spongy until the air is compressed (brake fluid is not compressable), by pumping the lever.  Someone else may chime in here about the air getting emulsified into the brake fluid and exactly what is happening in the fluid in the lines, but that's above my pay grade.    This will typically give you a temporary "hard" lever, but if you let it sit, the lever will go spongy again.  You'll then have to pump it again to get the feel back.

The only other way the lever would just drop to the bar is if the fluid was getting bypassed somewhere such as past a moving seal in the master.

This all presumes that you aren't finding a puddle of DOT3 on your garage floor.  

That ABS system has a LOT of line length and couplings to trap air.  If you absolutely KNOW you got all the air out, then look at the master.  If you THINK you got all the air out, you didn't.    Bleed them again!

Here's the thread from my full FJ rebuild regarding the bleeding of the front brakes (with ABS)

http://www.fjowners.com/index.php?topic=6300.msg55685#msg55685

That should keep you busy!  

Cap'n Ron. . .

[Tex]

     Ok so I'm going to attempt to do what you outlined on your thread. But first I need to be enlightened on the working's of the front break. From what I see on my FJ is the brake line from the master going down and a split right under the fairing going to each caliper. Where are all these other lines that you are referring to? Where is the ABS pump? Is all of this behind the fairing? How does this system work?

    I did look on Randy's site but I couldn't find a front rebuild master cylinder kit for a 93 ABS FJ just the non ABS kit.  Hmmm.

   Who sells the mighty vac?

Thanks Captn Ron

Scott

[Harvy]

Scott.... if your lines are as you describe, then you either do not have an ABS system (ie. someone has replaced the side panels with ABS model panels) or the ABS system has been bypassed.
The pump is in the tail section if it is still fitted.
Master cylinder rebuild kit is the same whether ABS or not.

Harvy

[racerrad8]

Master cylinder rebuild kit is the same whether ABS or not.

Harvy

I know this topic is for the front brakes, but based on experience the rear master cylinder is not the same on the ABS Vs. Non-ABS models.

I do stock both of the applicable kit for both.

Randy - RPM

[FJ_Hooligan]

Scott.... if your lines are as you describe, then you either do not have an ABS system (ie. someone has replaced the side panels with ABS model panels) or the ABS system has been bypassed.
The pump is in the tail section if it is still fitted.
Master cylinder rebuild kit is the same whether ABS or not.

What Harvey says about the lines is correct.  Sounds like someone may have removed the ABS.

The pump, however, is located behind and below the fuel pump under the right side cover, next to the shock.  The ABS "brain" is under the tail section.

[Capn Ron]

Yeah, what Harvey said.   

The ABS pump is on the right side of the bike just behind the fuel pump.  If you're tracing the brake line coming off the front brake master cylinder, it sort of dissapears into the fairing.  If you then trace the brake lines coming off the front brake calipers, they go up to a splitter and then you'll see a single line, going up into the fairing.  On the ABS model, it's easy to assume that the one going down into the fairing is the other end of the one going up into the fairing.  If the ABS system is still fully intact, those are two different lines that just happen to be next to each other and between them are a couple of hard lines, a couple of soft lines and the associated fittings to run the fluid all the way back to the ABS pump...then all the way back up front.

Here's the map of the entire system:



The other possibilities are what harvy pointed out.  A previous owner pulled the ABS system ...or... A previous owner put ABS side plastic on a non-ABS model.  Oh...wait.  You're is a '93...it definitely came with ABS from the factory.  You can take a look to see if the ABS pump is still on the bike, but the process of bleeding...and all the stated theories are exactly the same either way (just easier to bleed a non-ABS bike).

Cap'n Ron. . .

[spsmith_fj1200]

     Ok so I'm going to attempt to do what you outlined on your thread. But first I need to be enlightened on the working's of the front break. From what I see on my FJ is the brake line from the master going down and a split right under the fairing going to each caliper. Where are all these other lines that you are referring to? Where is the ABS pump? Is all of this behind the fairing? How does this system work?

    I did look on Randy's site but I couldn't find a front rebuild master cylinder kit for a 93 ABS FJ just the non ABS kit.  Hmmm.

   Who sells the mighty vac?

Thanks Captn Ron

Scott

Harbor Freight has the MityVac

http://www.harborfreight.com/automotive-motorcycle/brakes/mityvac-vacuum-pump-39522.html

[Capn Ron]

I use this one from Moeller...



It's a little spendy, but will hold more than you will ever need!

Cap'n Ron. . .

[Harvy]

Oh...wait.  You're is a '93...it definitely came with ABS from the factory.

Is that right Ron?...... maybe in the US, but over here in Aus FJs were available non ABS right up til the end of production.....


Cheers
Harvy

[Bones]

Mine is a 93 with no abs. Has your bike got the abs light in the dash or the low fuel light.

[Capn Ron]

Oh...wait.  You're is a '93...it definitely came with ABS from the factory.

Is that right Ron?...... maybe in the US, but over here in Aus FJs were available non ABS right up til the end of production.....


Cheers
Harvy

In the states, ABS was optional on the '92 models...40% were sold with this at at $1200 premium over the non-ABS version.  ABS was standard on the U.S. 1993 models.

Cap'n Ron. . .

[Dan Filetti]

I use this one from Moeller...



It's a little spendy, but will hold more than you will ever need!

Cap'n Ron. . .

Is that Sweedish made?

http://m.youtube.com/watch?v=Za7bHIKsxc4



Dan