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  #1  
Old February 25th, 2012, 03:00 PM
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Bryan Krill
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Poor braking

I have a '95 NAS '90 SW and I'm experiencing poor braking when you apply the them for a quick /panic stop from normal highway speed. The pedal doesen't fade away but the brake effectiveness goes away. I pulled the wheels and pads and they looked very good, but I noticed the rear discs had surface rust on them and the pads looked like they were new. The manual shows a g-valve in the system, not sure if this the equivalent of a purportioning valve, and I suspect this may be the culprit. Any insight would be greatly appreciated!
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  #2  
Old February 25th, 2012, 03:16 PM
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Jason England
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have you checked your fluid? fresh fluid helps.

if the rear discs have rust and pitting ... likely they are not working well, despite how they look. maybe the PO replaced pads but not the disks?

I'm also about to change my rubber brake hose lines for braided ... the rubber ones degrade over the years and can expand under braking ... this reduces the brake effectiveness.

Generally a defender brakes are pretty decent if everything is in good condition.
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  #3  
Old February 25th, 2012, 05:03 PM
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Check the pressure reducing valve below the heater box. I have had a couple of D90s through the shop with poor braking that ended up having stuck valves. Like yours, the rear brakes showed signs of no wear on the parts. To check, try bleeding the brakes. In both cases it was almost impossible to get fluid flow through the rear calipers.
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  #4  
Old February 25th, 2012, 08:24 PM
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Bryan Krill
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That's exactly what I was thinking of doing next, I'll try bleeding the whole system but I'll do the rear first.

Thanks!
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  #5  
Old February 25th, 2012, 10:03 PM
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You should be changing your fluid every couple of years, or at least when the fluid is darker than tea.

With the right tool, a Mity-Vac, this is a one man job.

Yes, do the rears 1st, as they are the farthest from the brake fluid reservoir, suck out all the old fluid in the reservoir 1st and fill it with new. Use DOT 4 fluid.

Then use a Mity-Vac to suck clean fluid to each wheel bleeder. Be sure to keep the reservoir full as to keep from sucking air into the system.
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Old February 26th, 2012, 08:29 AM
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Bryan Krill
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Thanks Dennis, I have such a tool.
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  #7  
Old February 26th, 2012, 12:26 PM
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Quote:
Originally Posted by Dennis View Post
Then use a Mity-Vac to suck clean fluid to each wheel bleeder. Be sure to keep the reservoir full as to keep from sucking air into the system.
Pressure bleeding is better, IMO.
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  #8  
Old February 27th, 2012, 09:55 AM
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Bryan Krill
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Well the ole Mighty Vac is not so mighty anymore. Not surprised, haven't used it in over 20years. Ordered a Motive power bleeder yesterday and will report back with results.
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  #9  
Old February 27th, 2012, 10:55 AM
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For forcing through the possibly plugged valve, turn on the engine and use the brake pedal.... That is a 1000+ psi.... The pressure bleeder is 20 psi....

If it does not get through with the pedal pressure, it will need to come apart.
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Old March 1st, 2012, 07:23 PM
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Bryan Krill
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Well, power bled the brakes today. I tried the rear first and couldn't get any fluid through and even tried the engine on and using the foot pedal method with no results. The front brakes bled fine. Does anyone know if the pressure regulating valve is a servicable part? My book doesn't even mention this valve it only refers to a G valve. If the valve is not serviable, does anyone know a good source to purchase a new one?

Thanks in advance--Bryan
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  #11  
Old March 1st, 2012, 08:57 PM
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Quote:
Originally Posted by floatflyer View Post
Well the ole Mighty Vac is not so mighty anymore. Not surprised, haven't used it in over 20years. Ordered a Motive power bleeder yesterday and will report back with results.
Which Motive did you order? The 0100?
http://www.motiveproducts.com/catalo...eder--0100.htm
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  #12  
Old March 1st, 2012, 09:28 PM
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Quote:
Originally Posted by nathanwind View Post
Which Motive did you order? The 0100?
http://www.motiveproducts.com/catalo...eder--0100.htm
Yes, the 0100 or if you want a little nicer the 0109, http://www.motiveproducts.com/catalo...eder--0109.htm
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  #13  
Old March 1st, 2012, 09:29 PM
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Quote:
Originally Posted by floatflyer View Post
Well, power bled the brakes today. I tried the rear first and couldn't get any fluid through and even tried the engine on and using the foot pedal method with no results. The front brakes bled fine. Does anyone know if the pressure regulating valve is a servicable part? My book doesn't even mention this valve it only refers to a G valve. If the valve is not serviable, does anyone know a good source to purchase a new one?

Thanks in advance--Bryan
I would try taking it out and blowing back through it. I've no idea how they are built but it is worth a try.
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  #14  
Old March 2nd, 2012, 12:36 AM
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Bryan Krill
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I ordered the Motive 0100 set up for 45mm caps. Seemed to work fine when I purged the front brakes. I'm going to pull the valve tomorrow and see what I can find. More later.

------ Follow up post added March 1st, 2012 09:38 PM ------

PS... I ordered the Motive from Summit Racing, it was $59.41 shipped. I got it in two days.
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  #15  
Old March 2nd, 2012, 06:51 PM
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Bryan Krill
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Well problem solved. It turned out to be the Balance valve also known as perportioning valve. When I took it apart it was obvious it was out of adjustment and was totally closed off to passing any fluid to the rear brakes. A penny is worth something these days cause that's what I used to adjust the valve. If you ever have to take one apart it's quite a simple device. Anyway thanks to all who responded!
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