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  #16  
Old February 12th, 2019, 12:20
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Hypoid Hypoid is offline
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Re: Brake booster and MC swap issue

Quote:
Originally Posted by jeeping4fun View Post
No I have a dana 44 with drums. I just upgraded the MC and booster to a 96 XJ.
Adjust the shoes until you think they are too tight.

Is it lifted?
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  #17  
Old February 12th, 2019, 12:42
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Re: Brake booster and MC swap issue

Yes it is lifted. I had to replace ebrake cables also. I lifted it 5.5", swapped the dana 44 and all brake lines. Hence the issue it tracking the problem. It's all been messed with in the last 2 months. You think the rear pads aren't adjusted correctly? Causing the peddle feel?
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  #18  
Old February 12th, 2019, 13:18
Jim Malcolm Jim Malcolm is offline
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Re: Brake booster and MC swap issue

I apologize for bringing the spring into the conversation. I misread the initial post and for some reason thought you had discs in the rear. The advice that there may be a bubble trapped in the "proportioning" valve is still true. DO NOT change the spring or plunger unless you have disc brakes in the rear, in which case, you should replace both with ones from a ZJ.
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  #19  
Old February 12th, 2019, 13:41
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Re: Brake booster and MC swap issue

Lol not a problem. I was thinking something was misunderstood.

I'll crack the proportioning valve and see if air comes out. Bleed the system again and also change the bleeder valves. If that doesnt work I just order another brand new MC. So then I'll swap that. If that doesnt work I'll set it on fire. Thanks for the help!
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  #20  
Old February 12th, 2019, 14:34
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Re: Brake booster and MC swap issue

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Originally Posted by jeeping4fun View Post
If that doesnt work I'll set it on fire.
I'll give you fiddy bucks for it!

A buddy had similar problems after replacing the wheel cylinders on his lifted XJ. He brought it to me on a snowy day. Given the driving conditions, I could feel the rear brakes engaging at 50% pedal travel, the fronts started working at 75% pedal travel.

I forget how much lift it has, but it rotated the axle housing enough that the wheel cylinders do not sit level. He theorized the wheel cylinders had air trapped in them. We put jack stands under the axle, pulled the wheels and drums. The drums slid off with no effort! Now, we are looking at two potential problems:

We bled the hydraulic system by unbolting the wheel cylinders from the backing plate, and used a pry bar to make it level. I did observe a few air bubbles when we bled the driver side, did not see any on the passenger side.

When we tried to adjust the shoes, we found one adjuster was very difficult to turn, and the other was frozen. We cleaned and lubed the adjusters. We adjusted the shoes to the point the drums were difficult to push over the shoes (the drums have wear ridges).

Before any further adjustments, we have full braking at 30% pedal travel.

The point is, you can have more than one problem. The only thing you can do is go through your equipment in a methodical process, to make sure everything is working as it should.
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  #21  
Old February 12th, 2019, 14:37
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Re: Brake booster and MC swap issue

Very good to know. The tears were completely empty do to the axle swap. I set the pinion angle perfect (pointed up do to sye) so they very well could have air trapped. I'll take a look!
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  #22  
Old February 18th, 2019, 13:36
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Re: Brake booster and MC swap issue

So the noise is come from the booster not the MC like I thought. The noise is coming from the vacuum line. If i pull the line and plug it with my finger it wont do it. Probably a bad booster like suggested before. Would a bad booster cause the brakes to act weird like air in the lines?

I cracked the prop valve and let it leak for a couple seconds. Also the rear brake cylinders where NOT level at all. I raised the rear as high as I could and bled the whole system again. After all that it's still the same. I have a new master cylinder and am going to pick up another booster. I dont want to replace the MC again if I dont have to but do you guys think a bad booster would cause this?

Thanks for all your suggestions. This is driving me nuts and I just want to drive this thing after months of working on it.
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  #23  
Old February 18th, 2019, 14:27
Jim Malcolm Jim Malcolm is offline
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Re: Brake booster and MC swap issue

One of those "paid for itself many times over" tools is a hand pump vacuum bleeder. $22 on Amazon with a blow molded case or your local parts store may have one. I tried quick bleeders once, did not like them one bit and that's when I purchased the vacuum bleeder.

There shouldn't be any noise, so I agree that the booster is suspect. MC would make noise as it's being applied, not just sitting there.
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  #24  
Old February 18th, 2019, 15:38
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Re: Brake booster and MC swap issue

I'll try that next time I mess with it.

Just to make sure I'm not an idiot.

The lines on the MC the front one goes to the front brakes and the rear go to the rear brakes? That's how I have it in the MJ with the renix prop valve.

In my 96 XJ the front line goes to the rear brakes and the rear line goes to the front.

Did I goof them up or do the different prop valves route it different? I'm not even sure it matters.
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  #25  
Old February 19th, 2019, 13:27
Jim Malcolm Jim Malcolm is offline
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Re: Brake booster and MC swap issue

On both my 88 and my 94, the line at the back of the MC (closest to the firewall) goes into the rear port on the PV, but it's actually for the front brakes. The front line on the MC goes to the front port on the PV (closest to the grill) and is for the rear brakes. I have the 95-96 booster and MC in both. It does matter which is connected to which...
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  #26  
Old February 19th, 2019, 13:53
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Re: Brake booster and MC swap issue

Ok maybe I got it backwards. Let me look again. I got a new booster coming tomorrow. So new booster and MC again this weekend. I've gone through $100 in brake fluid lol. Thanks
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  #27  
Old June 8th, 2019, 13:52
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Brake booster and MC swap issue

Working on replacing my booster now. Will be installing 44s with discs front and rear in the near future. Thought about putting dodge 2500 master in to move enough fluid to stop 37s. On 33s now with 8.25 w drums on rear.

Doesn't sound like there is a way to set my brakes up with bigger MC and booster so it will work with both systems?

Blew booster last time out (whoosh pedal) and want to upgrade. Got booster out of rig but not sure what I need to order.

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