HandsomeMike

1989 Vette- If I install new front calipers and re-use my existing brake lines, do I need to bleed the brakes after attaching the existing lines to the new calipers? If so, just the new front calipers or all four? Thanks!

Cliff Harris

The front and rear braking systems are completely isolated from each other, so you could just bleed the fronts. Why not do all four?

Having fresh brake fluid in the system is always a good thing.

c4cruiser

You certainly need to bleed the front brakes to get fluid into the calipers.

But as mentioned, it's not a big job to bleed all 4 lines and if the fluid is more than 3-4 years old, it should be done when the calipers are replaced. You will need about a quart to do a complete flush and fill.

HandsomeMike

Good to know that the front and back are separate. I had a new MC put in back in November so it's very clean. If I just bleed the front, does it matter which side I do first?

Just BOB

I'd suggest you bleed the OLD calipers first so you are pushing old, nasty fluid through them instead of through your brand new calipers.

As Cliff Harris and C4Cruiser suggested, you might as well flush the whole system while you are at it.

John A. Marker

Bleed the farthest away from the brake reservoir first. I would remove as much of the old fluid as you can and replace it with new. Then bleed the rear brakes starting with the passenger rear, then driver's rear. Then move to the front..passenger side first then driver's. Always watch the reservoir to be sure that there is fluid in it as you bleed the brakes. You don't want to suck air into the system.

I usually put a clear plastic 3/16" ID tube over the brake bleeder nipple when I bleed my brakes. This way you can see the air bubbles pass through if there is any air in the system and you can see the new fluid. I put the end in a glass jar to catch the fluid.

I also installed speed bleeders on all of my calipers. Makes the job much easier.

Cliff Harris

The general rule of thumb is to bleed the caliper farthest from the master cylinder first. That would be the passenger side (front or rear).

65Z01

I use a similar setup but with some brake fluid in the jar. That way I can bleed the system using stock bleeders and still not suck up air upon pedal release.

Cruisinfanatic

how would you get the air out of them if you didn't bleed?

HandsomeMike

I've never done brakes before and didn't know if air would get in the lines just by disconnecting from the caliper. That's why I asked the question...

John A. Marker

The new calipers do not have brake fluid in them.....there is air. You have to attach brake lines and bleed the calipers.

Again we suggest that you bleed all and get rid of the old brake fluid. Old fluid will absorb moisture over time and reduce the effectiveness of the braking function. If all the fluid was changed out in November of last year, then you are okay in just bleeding the front. Just be sure to keep the reservoir close to full as you bleed the brakes and never let it go empty. This is really a two person job. One to slowly pump the brake and the other to keep the reservoir full and watch the fluid come out the the caliper you are bleeding. Use a 3/16" ID clear plastic hose over the bleeder so you can see the air bubbles being forced out. Keep slowly pumping the brakes until all the air has been removed and your seeing clear fluid being forced out. Without the hose you can't tell if your getting air or fluid.

HandsomeMike

Thanks John!

r07z06

replaced all calipers, pads, and lines but after bleeding I don't have a hard pedal. Any thoughts??

antfarmer2

Still not bleed and has air in them I have a vacume pump from harbor frieght that will pull the fluid and air works great and no mess