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Brake Bleeding Questions...

3K views 16 replies 8 participants last post by  V-Love 
#1 ·
OK, I've bled brakes on regular single piston cars a number of times. And I've been the pedaler on brake bleeds ever since my father could position me behind the wheel.

I know the basic principles on replacing the fluid in the master cylinder and bleeding each corner slowly until new fluid comes out and not letting the master drain too much and let air in the system. That I've got.

But I'm putting in new Motul 600. It states to flush the entire system and not mix it with other fluids. How do I do that? This is the first time it's mattered that I don't mix fluids. You can't empty the entire system and start from scratch, can you?

Also, I bought a one person bleeder system that runs off compressed air and it extracts the fluid from the bleeder. When I was at VIR, they said to not use mechanized systems like that for racing brakes. Now, I don't know if he meant real racing brakes with 2 master cylinders or if he meant to not use those systems in any application where hot laps are involved.

The FAQ only gives bleeding order. Anyone care to help?
 
#2 ·
I use a pressurized tank and ATE blue and amber. I've run the car a few times a year at Beaverun with speed varying between 40 and 120 on a 1.6 mile course - so the brakes get a workout.

Haven't had any problems yet. I push less than one quart through when bleeding and look for the color change. But there is no concern about compatability between blue and amber so if I'm a little lazy, it doesn't much matter. The color change lets me know that the old fluid in the pistons is out. On each wheel, I do outboard then inboard bleed screws.
 
#4 ·
I just went through this exercise on my Viper SRT which has a similar Brembo setup. The guidance I received is as follows: Drain down the resevoir to the lowest point; put the new fluid in and fill to the top marker. Drain down again twice; by the third fill you should have ridden the system of the older fluid. And you know the drill - you start(drain) with rear passenger, then rear driver side,front left and right(closest). I used a vaccum pump bleeder. I have had no issues and this is the procedure used by VCA.
 
#5 ·
Actually, the FAQ says it differently.

Bleed order:
* Right rear inner
* Right rear outer
* Left front inner
* Left front outer
* Left rear inner
* Left rear outer
* Right front inner
* Right front outer
(Eight bleeder screws on a GM product... unbelievable! )

The problem is that I boiled my ATE at VIR and don't want to do that again. So I'm running Motul. But Motul says don't mix it with other fluids. So if I empty out the reservoir, does filling it with the Motul "mix" it?
 
#17 ·
Actually, the FAQ says it differently.

Bleed order:
* Right rear inner
* Right rear outer
* Left front inner
* Left front outer
* Left rear inner
* Left rear outer
* Right front inner
* Right front outer
(Eight bleeder screws on a GM product... unbelievable! )

The problem is that I boiled my ATE at VIR and don't want to do that again. So I'm running Motul. But Motul says don't mix it with other fluids. So if I empty out the reservoir, does filling it with the Motul "mix" it?
BIGJim (or any helpful member), Can you link me up with the brake fluid change instructions. I was looking around the FAQ and found these generic instructions:
http://www.cadillacfaq.com/faq/answers/bpadchange/bleedwhite.html
Looks like Jim may have found something better than me. I was looking for V specific as done by a forum member. Like the brake pad change by Dreamin' found here:
http://www.cadillacfaq.com/faq/answers/bpadchange/index.html
Thanks.
 
#6 ·
You will reach a point where the mixed product is flushed. Do not believe there is "backwash" chemical reaction to this process. Actually when you bleed the inners/outers you will notice that there is not that much fluid stored in the calipers. Once the new fluid hits the calipers, it will push the diluted stuff out.
 
#9 ·
What model bleeder did you go with? Are tires removed for this procedure to access rear bleeders?
I was thinking that if you completely drain your system first it will be way more airbound than just adding fluid. One bubble = trouble. I will buy an extra quart or two and flush it real good. Expensive but cheaper than new brakes. Caddy did mine last and they got soft way too quick. I imagine a helper did it. I never did a brake fluid change but I have bled quite a few oil lines and fuel lines for diesel trucks that lost prime. Plus, I have the FAQ and this great forum.
 
#10 ·
Did you by the bleeder from CDOC when we were at VIR? It does not matter much at this point but I could have got it for you at cost from CDOC.
 
#11 ·
DOH! that was me. I also bought some HP+'s for the front. Jim bought some Hawk Blues for the front's on his.

Ohh well hindsight it 20/20. Glad to give CDOC some dough :D

-Chris
 
#12 ·
Definitely don't drain the system. The bubbles can be hard to remove.

The pressure bleeders probably work OK for replacing fluid, especially when there is no air, and calipers like ours which don't seem to trap bubbles.

The impetus to do it the old fashioned way is probably because some bubbles will not move unless you really squeeze them under pressure. One reason is simply because the bubbles get smaller under pressure, so they can move easier. For racing brakes, any bubble is anathema, because no matter how small they start, bubbles get bigger when the fluid gets hot.

I wouldn't worry about mixing the fluids, as long as they are all DOT3/DOT4 and you get fresh fluid into the calipers.

Michael
 
#14 ·
I bought the Motive one from CDOC:

This one fits GM cars for $70

http://www.cdoc.com/detail.asp?id=12259&str=1000-0614&name=Brake+Bleeding+Tools

If you go the track with friends or have other makes, you can get the PRO kit, that fits nearly every brake resevoir.

http://www.cdoc.com/detail.asp?id=33609&str=1000-0614&name=Brake+Bleeding+Tools

Seemed to work fine for me. I flushed my entire system at the track. Filled the resvoir up with some ATE Blue. If you are gonna do a full flush, I'd fill the reevoir up with half a quart, and then re fill after the 2nd or 3rtd wheel. It can get a bit messy, if you stiull have a bunch of fluid left in the bleeder. You either pull it off, and hope to mop up the mess, or take the time to bleed all the fluid from the container. (This takes longer than you'd think, because if you pressurize more than 20 PSI, then you risk poping the connection off to the brake resevoir, and getting fluid everywhere).

My friend has one, and he doesn't even put any fluid in it, rather he turkey basters out as much of the old fluid as he can, fills the resevoir to the top, then screws on the power bleeder, and presurizes it. This is fine to do a quick bleed. To flush, you may have to repeat this for every wheel.

The bigest thing the pwoer bleeder brings to the table is you can do it yourself, and don;t need an extra set of legs to do the old pump-open-close-pump routine.

I'd love to hear what others do. I'm somehwat intregued by those autobleeder's. I probalay won't get them, because I'm not bleeding/flushing often enough to have it make fiscal sense, but still the idea sounds interesting.

-Chris
 
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