Jeep Commander Forum banner

1 - 6 of 6 Posts

·
Registered
Joined
·
12 Posts
Discussion Starter #1
I am replacing my front driver brake caliper. Do I have to bleed all four brakes, the front two or just that caliper??
 

·
Registered
Joined
·
145 Posts
You can bleed just the one side.But brakes are your life.Do you really want to chance it? Once you crack open that line,air and moistrure are going in. Also If the vehicle has any amout of miles on it,you really should replace the other side.Thew new caliper will nearly always work better than the old one.Also don't forget about the ABS system and how to treat that.
 

·
Registered
Joined
·
3,037 Posts
I "think" (don't know for sure) the ABS on the Commander pretty much isolates each brake caliper. For NON ABS vehicles the dual master cylinder creates two brakes circuits, usually front/rear, but some are arranged in an X pattern, i.e. front left on the same circuit as rear right, etc.

You can often get away with bleeding just the caliper replaced, but its adviced to also bleed the other brake on the same circuit cause its very easy to get air in the line for the other brake on the same circuit during the replacement.

And I 2nd advice that you should bleed all of them to flush and replace all the existing brake fluid. I know they say brake fluid lasts the life of the vehicle, it doesn't, it is safer and your brakes will stay trouble free longer if you replace all your brake fluid every couple of years.

Use the recommended brake fluid, do NOT use a higher DOT spec than recommended thinking you get better protection. You don't, the higher the DOT spec, i.e. DOT4 vs DOT3, the shorter the brake fluid lasts and the more and faster it absorbs moisture out of the air. So if the O.M. recommends DOT3 it is better to use DOT3 than DOT4, don't fool yourself because the bottle says DOT4 has a higher boiling point, if the O.M. recommends DOT3 than the boiling point of DOT3 is more than high enough, and DOT3 will be a better protecting, longer lasting fluid than DOT4.

Of course there are some alternative brake fluids out there, like Castroil LMAF, or Valvoline Synthetic (marketing ploy, all brake fluid is synthetic), that the fluid is as well protecting and long lasting as DOT3 but has higher boiling points than DOT4. Those would be fine to use as well. I like Castrol LMAF, but I can never find it in the stores.

Finally ABS, you should be able to bleed your brakes and NOT get air into the ABS module (some early ABS modules would get air in them). The only way to bleed the ABS module is too use a very specific OBDII tool that will send a command to the ABS module to operate the ABS pump and valves while you have the appropraite bleed screw open. You pretty much have to go the dealer or a well equipped independent shop to have them do it. No, the $100 OBDII code readers at Walmart can NOT do this.

But honestly, you do NOT have to bleed the ABS module, unless you screw up and get air in it. Just do a normal brake bleed at 4 points, enough to replace all the fluid. The next time you're in snow/gravel/really wet surface, hit the brakes enough to activate the ABS and it will circulate that new fluid into the module, the old fluid will mix into the new, but you still replaced like 97% of the fluid, so your good.
 

·
Registered
Joined
·
3,037 Posts
Speed Bleeders a.k.a. one man bleed screws, they are bleeder screws with a one way check valve in them. Well worth the money, like $20 per vehicle. Just replace your bleeder screw with them, crack the bleeder screw and pump the pedal (put a tube on them to a bottle of course), the check valve won't let air into the system, so you don't have to have a 2nd person opening and closing the bleeder screw and coordinating the pedal pressing with the wrench turning.

With speed bleeders, I've even screwed up and ran the reservour dry and sucked air into the master cylinder. The speed bleeders actual bleed the air out of the Master Cylinder by just pumping the pedal.

Some people use vacuum bleed tools, a hand vacuum pump they connect to the open bleeder screw and suck the fluid through. Shops have pressure bleeders that they connect a fitting to the cap of the master cylinder and use pressure to force the fluid through.
 
1 - 6 of 6 Posts
Top