Discussion:
Sensetive Brakes

When applying brakes there is no modulation. They are either on or off & nothing in between. They basically lock up.
I heard there was a Service gram on this. Anybody know anything about this??
  • Posted 21 Feb 2018 08:21
  • By Horse
  • joined 11 Jan'11 - 38 messages
  • Wisconsin, United States
Jeff Bykowski
Showing items 1 - 7 of 7 results.
The brake fluid is separate from the oil in the differential. The spec calls for Dexron fluid in the master cylinder reservoir. This fluid is contained in the brake piston by seals. These seals are what gets damaged when DOT3 is added to the brake reservoir. The volume of oil in the brake system is separate from the differential. The damage done to the brake discs occurred over time. The Dexron fluid will mix with the JD20 without causing great damage.
  • Posted 22 Feb 2018 09:08
  • Modified 22 Feb 2018 09:09 by poster
  • By BREWSKI
  • joined 10 Jan'12 - 1,699 messages
  • Nebraska, United States
So u r saying dot 3 fluid worked past piston into the diff fluid & caused contamination of the brake disc material causing adverse braking. How can a small amount of dot 3 have that much effect on a large capacity differential. I m assuming there is J 20/ newer spec j 21 universal in the axle which is used to lubricate brakes & carrier. I get where you are going with this.

Do u know if booster has a adjustable relief?
  • Posted 22 Feb 2018 07:52
  • Modified 22 Feb 2018 07:55 by poster
  • By Horse
  • joined 11 Jan'11 - 38 messages
  • Wisconsin, United States
Jeff Bykowski
If you are not loosing fluid and there is no evidence of brake drag. I would change the fluid in the drive axle and see how the brakes work. The wet brake system does not take a lot of pedal pressure to activate compared to the dry brake system. I have had customers add DOT3 fluid to the brake system. The brakes began to drag almost right away. The DOT3 fluid destroys the pad material and swells up the piston seals. didn't take long and there was no brake pedal and you could not get the system to bleed. Make sure you use the proper fluid in the axle. The new spec is J21A- John Deere or equivalent.
  • Posted 22 Feb 2018 07:44
  • Modified 22 Feb 2018 07:47 by poster
  • By BREWSKI
  • joined 10 Jan'12 - 1,699 messages
  • Nebraska, United States
It has wet brakes per serial # G4v05998J. S100 FTBCS
I was informed that if dot 3 was used instead of ATF in the reservoir the brake piston seals will swell up causing the b piston to hang. I don t think this is the case although we have not looked @ the b reservoir fluid yet. We just started working on this unit & don t know the history except they purchased @ auction.
When I drove unit it seems the booster pressure is too high. Brakes don t drag when you release so I don t think its piston related.
Can the booster relief pressure be adjusted??? Or maybe inching overlap pressure adjustment??
  • Posted 22 Feb 2018 03:28
  • By Horse
  • joined 11 Jan'11 - 38 messages
  • Wisconsin, United States
Jeff Bykowski
Do you have the serial number?
  • Posted 22 Feb 2018 00:31
  • By BREWSKI
  • joined 10 Jan'12 - 1,699 messages
  • Nebraska, United States
Thats a good question. I have a call in to a local dealer to find out what the gram is for that specific serial #
  • Posted 21 Feb 2018 09:41
  • By Horse
  • joined 11 Jan'11 - 38 messages
  • Wisconsin, United States
Jeff Bykowski
Are these dry brakes or wet brakes?
  • Posted 21 Feb 2018 09:30
  • By BREWSKI
  • joined 10 Jan'12 - 1,699 messages
  • Nebraska, United States

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