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Author Topic: Toad Brakes Locking Up  (Read 654 times)

DaveRB55

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Toad Brakes Locking Up
« on: October 21, 2017, 08:55:54 AM »
Hello,
We are on our virgin shakedown trip and have run into a problem.  Have the M&G brake system installed in our CRV.  Came over a hill with a redlight that turned and had to make a somewhat quick stop.  Yes, smelled some brakes /rubber and heard some screeching which was surprising as I did not feel it was that extreme a stop. Drove my car into town a day later and felt thumping as I got up to speed.  Left front tire had a flat spot and rubber ground down.  Had M&G installed at Athens TX factory.  Can’t understand why just one tire locked up and not both.  Having brakes checked this morning on CRV but don’t expect anything as car was braking fine.  Have contacted M&G who says they can reduce air pressure but again problem should be with both tires.  Anyone heard of anything like this.  ABS does not engage when towing.
2016 Winnebago Suncruiser
Christened “The Beast”
2010 Honda CRV
M&G Brake system w/Blue Ox Avail

Gary RV_Wizard

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Re: Toad Brakes Locking Up
« Reply #1 on: October 21, 2017, 09:19:23 AM »
It's not unusual for one wheel to lock up before the others in extreme braking. Simple variations in the brake adjustment and condition can lead to that.  The question is, "Is the M&G applying too much braking to the toad, to the point where a lock-up can occur?"

I would get the CRV brakes adjusted so that each wheel is as close as possible to the others in terms of lock-up adjustment, and then get the M&G braking action turned down a bit to stay well short of any lock-up.
Gary
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Gary Brinck
Summers: Black Mountain, NC
Home: Ocala National Forest, FL

DaveRB55

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Re: Toad Brakes Locking Up
« Reply #2 on: October 21, 2017, 09:39:55 AM »
Thanks Gary for the quick reply.  I’m headed to the shop to have the brakes checked.  I wasn’t aware brakes could be adjusted for equality in lock up and will follow that up.  m&g said they will help me to  adjust down the pressure...pretty expensive way to verify things are working!
2016 Winnebago Suncruiser
Christened “The Beast”
2010 Honda CRV
M&G Brake system w/Blue Ox Avail

Charlie 5320

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Re: Toad Brakes Locking Up
« Reply #3 on: October 21, 2017, 02:25:19 PM »
That car should have anti lock brakes on it. I'd be inquiring how the brake system you had installed could lock just one wheel. Something doesn't sound right to me.
2003 National Dolphin 5320
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taoshum

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Re: Toad Brakes Locking Up
« Reply #4 on: October 21, 2017, 03:28:16 PM »
Glad you found it so quickly!
07 Itasca Meridian 34SH.  '08 Jeep Sahara.
Taos, NM.

Utclmjmpr

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Re: Toad Brakes Locking Up
« Reply #5 on: October 21, 2017, 04:36:18 PM »
M&G is a system I've had for 18 years and nary a problem,, installed myself on two different vehicles. Presently on a Jeep Liberty.>>>Dan
38' American Tradition 38TT/330 turbo Cummins
Jeep liberty 4 down
72 VW Baja 4 down
Cedar City, Utah
USAF vet. 59-63
The difference between intelligence & stupidity is: intelligence has it's limits
      Albert Einstein.
President Western GM Coach chapter FMCA

ArdraF

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Re: Toad Brakes Locking Up
« Reply #6 on: October 21, 2017, 05:25:24 PM »
We had the M&G system on both our DPs with a Tracker, a Jeep Grand Cherokee, and an Acura MDX.  When you press the brake in the motorhome, all four toad brakes should engage evenly.  I remember when we got the Tracker hooked up we did a test where we drove both ways in a circle on gravel to test that all four brakes were working together.  Jerry and I talked about it and he thinks it is a problem with the CRV because, if it was the M&G system, all four toad wheel brakes would be locking, not just one.

ArdraF
ArdraF
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Utclmjmpr

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Re: Toad Brakes Locking Up
« Reply #7 on: October 21, 2017, 06:53:06 PM »
I think Ardra has it on the head,, the M&G system applies pressure at the master cylinder of the toad,, after that the braking system acts just like it would if you pressed the brake pedal with your foot.>>>Dan
38' American Tradition 38TT/330 turbo Cummins
Jeep liberty 4 down
72 VW Baja 4 down
Cedar City, Utah
USAF vet. 59-63
The difference between intelligence & stupidity is: intelligence has it's limits
      Albert Einstein.
President Western GM Coach chapter FMCA

Gary RV_Wizard

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Re: Toad Brakes Locking Up
« Reply #8 on: October 21, 2017, 07:17:31 PM »
Quote
That car should have anti lock brakes on it. I'd be inquiring how the brake system you had installed could lock just one wheel. Something doesn't sound right to me.


The antilock system will be inoperative when towing with the engine/ignition off. It's a computer controlled thing, plus it needs control over the toads own brakes to do anything.

Quote
I wasn’t aware brakes could be adjusted for equality in lock up and will follow that up.

Normal brake adjustment is to have all 4 wheels braking at the same level, but sometimes one gets out of adjustment or otherwise starts to do either more or less than  its share.  Any competent brake tech can make sure that all are braking the same. Once you are sure they are, then the M&G can't make one brake lock up any sooner than the rest, since it applies hydraulic pressure to the whole brake system at once.
Gary
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Gary Brinck
Summers: Black Mountain, NC
Home: Ocala National Forest, FL

Tom

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Re: Toad Brakes Locking Up
« Reply #9 on: October 21, 2017, 07:27:29 PM »
I too had the M&G installed by techs in Athens, although not at the factory.

Just for clarification, the M&G applies air to push a piston between the vacuum booster and the master brake cylinder. There's no way it can apply hydraulic pressure to only one brake.
Tom.  Need help? Click the Help button in the toolbar above.

Gary RV_Wizard

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Re: Toad Brakes Locking Up
« Reply #10 on: October 21, 2017, 07:33:50 PM »
Right - the M&G does them all the same. However, the car's own system does not necessarily respond evenly, i.e. one brake may "grab" sooner than the others. If the M&G applies more braking than desirable, that "grabby" brake will lock before the rest.
Gary
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Gary Brinck
Summers: Black Mountain, NC
Home: Ocala National Forest, FL

Tom

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Re: Toad Brakes Locking Up
« Reply #11 on: October 21, 2017, 07:43:54 PM »
My response was to clarify that it could not be the M&G system causing the problem, so it must be an issue with the car's braking system.
Tom.  Need help? Click the Help button in the toolbar above.

WILDEBILL308

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Re: Toad Brakes Locking Up
« Reply #12 on: October 21, 2017, 08:24:39 PM »
Did you pump the brakes to use up the vacuum in the brake booster before towing? Sounds like you need to dial back the pressure/brake force.
Bill
2003 Bounder 38N
300 HP 5.9 Cummins
Allison 3000MH Trans.
Towing 2014 Honda CRV
Home base Fort Worth, Texas
A man who carries a cat by the tail learns something he can learn in no other way.
-Mark Twain-

johnhicks

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Re: Toad Brakes Locking Up
« Reply #13 on: October 21, 2017, 09:54:28 PM »
  I believe a leaking wheel cylinder/caliper can cause a brake to grab. At least it did on my Tracker, but that was just in ordiinary driving and I could certainly feel it.

llib enad

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Re: Toad Brakes Locking Up
« Reply #14 on: October 22, 2017, 07:46:56 AM »
MG has a brake line pressure adjuster that is installed before the MG unit.  The MG factory installed one for my rig.  Used the gravel road test to adjust.

Bill Dane
99 Country Coach


Utclmjmpr

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Re: Toad Brakes Locking Up
« Reply #15 on: October 22, 2017, 06:16:44 PM »
  The M&G  has the input after the booster,,the booster has no vacuum without the engine running and does not "store" vacuum.>>>Dan
38' American Tradition 38TT/330 turbo Cummins
Jeep liberty 4 down
72 VW Baja 4 down
Cedar City, Utah
USAF vet. 59-63
The difference between intelligence & stupidity is: intelligence has it's limits
      Albert Einstein.
President Western GM Coach chapter FMCA

WILDEBILL308

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Re: Toad Brakes Locking Up
« Reply #16 on: October 22, 2017, 07:41:46 PM »
  The M&G  has the input after the booster,,the booster has no vacuum without the engine running and does not "store" vacuum.>>>Dan
Well yes it will store vacuum. I have chirped the tiers on my CR-V when I forgot to pump the brakes after shutting the motor off before towing. That first stop leaving a campground can be interesting. I don't know how long the canister will hold vacuum but.
Bill
2003 Bounder 38N
300 HP 5.9 Cummins
Allison 3000MH Trans.
Towing 2014 Honda CRV
Home base Fort Worth, Texas
A man who carries a cat by the tail learns something he can learn in no other way.
-Mark Twain-

nvrver

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Re: Toad Brakes Locking Up
« Reply #17 on: October 22, 2017, 08:00:50 PM »
Don't have the M & G system, but my 2013 CRV stores vacuum unless I push on the break 2 or 3 times to release it.  A few weeks ago I forgot to do that and in Lone Pine I had to hit the breaks and the CRV came to a screeching stop like you described without causing any flat spots on the tires.  Dick nvrver
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Utclmjmpr

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Re: Toad Brakes Locking Up
« Reply #18 on: October 22, 2017, 08:09:40 PM »
 Does your Honda manual tell you to do that?? If so the Honda is unique and daverb should have known that.>>>D
« Last Edit: October 22, 2017, 08:11:50 PM by utahclaimjumper »
38' American Tradition 38TT/330 turbo Cummins
Jeep liberty 4 down
72 VW Baja 4 down
Cedar City, Utah
USAF vet. 59-63
The difference between intelligence & stupidity is: intelligence has it's limits
      Albert Einstein.
President Western GM Coach chapter FMCA

Charlie 5320

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Re: Toad Brakes Locking Up
« Reply #19 on: October 23, 2017, 09:18:54 AM »
Does your Honda manual tell you to do that?? If so the Honda is unique and daverb should have known that.>>>D
Sorry Dan
Many cars store vacuum in the the booster. Some have a check valve on the vacuum hose going to the booster. They look like this.

https://www.walmart.com/ip/Dorman-Help-80190-Brake-Check-Valve/173650698?wmlspartner=wlpa&selectedSellerId=1148&adid=22222222227052480352&wmlspartner=wmtlabs&wl0=&wl1=g&wl2=c&wl3=152490426171&wl4=pla-263381516809&wl5=9022633&wl6=&wl7=&wl8=&wl9=pla&wl10=112562587&wl11=online&wl12=173650698&wl13=&veh=sem
« Last Edit: October 23, 2017, 09:21:04 AM by Charlie 5320 »
2003 National Dolphin 5320
496  8.1  Workhorse

98 Damon Daybreak 3130
GM Vortech 454  4L80E
SOLD

Utclmjmpr

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Re: Toad Brakes Locking Up
« Reply #20 on: October 23, 2017, 11:11:35 AM »
 I checked with my brother whom has a 2017 Winnie class "C" and a 2014 CRV with the SMI braking system.. I learned that the SMI actually uses a vacuum designed system utilizing the Honda booster to provide supplemental braking,,learn something new on this board daily.>>>Dan
38' American Tradition 38TT/330 turbo Cummins
Jeep liberty 4 down
72 VW Baja 4 down
Cedar City, Utah
USAF vet. 59-63
The difference between intelligence & stupidity is: intelligence has it's limits
      Albert Einstein.
President Western GM Coach chapter FMCA

jubileee

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Re: Toad Brakes Locking Up
« Reply #21 on: October 23, 2017, 02:25:10 PM »
Disc brakes are inherently self adjusting, all drag a little bit. Air in the hydraulic brake system can cause a wheel lock up, though in my experience, it’s usually the right front. Then there’s a rough rotor, scored pads, or leaking caliper. I would think that when you are driving the toad and brake hard, it would pull to the left even though the anti lock system would prevent lock up.

DaveRB55

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Re: Toad Brakes Locking Up
« Reply #22 on: October 23, 2017, 04:33:48 PM »
Hi all, back on line and thank you all for your concern and input. 

We’ve motored up to Caprock Canyon and did not hook up the braking system.  I could definitely feel the lack of toad braking.  I did have my brakes checked at a Goodyear store and was told my CRV brakes were fine. No codes thrown off from abs, car stops evenly with no pull.  As some of you have mention M&G woks without ABS but still should apply same pressure to wheels.  M&G is sending me a reducer that can be plugged to the air outlet from the pressure power unit between the unit and CRV.   Said the CrV’s are relatively light and may require lower pressure.  BTW, had this installed at Athens as well.  From the web, I thought that was their home base (small operation).    He did not have any answers as to why only one wheel locked up just that the system should not cause that and reducing pressure should help.  Committed to help me with some testing on gravel when installed.

Will check the manual again but do not recall seeing any warning of brake booster.  I tried calling Honda but only got referred to a dealer.   Not sure I understand the brake booster issue and if there was a buildup wouldn’t it again be applied to all wheels?  I do remember the booster unit coming on after hooking up toad. Need to do more thinking on that

Also did ask Goodyear mech about brake adjustment and he said there are none.  Maybe you I’m not asking the question right or maybe the wrong mech?

i’m without question a novice at this.  Very thankful for all your assistance and suggestions.  We are on the road till next week.

Dave
2016 Winnebago Suncruiser
Christened “The Beast”
2010 Honda CRV
M&G Brake system w/Blue Ox Avail

William52

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Re: Toad Brakes Locking Up
« Reply #23 on: October 25, 2017, 07:50:41 AM »
It's not unusual for one wheel to lock up before the others in extreme braking. Simple variations in the brake adjustment and condition can lead to that.  The question is, "Is the M&G applying too much braking to the toad, to the point where a lock-up can occur?"

I would get the CRV brakes adjusted so that each wheel is as close as possible to the others in terms of lock-up adjustment, and then get the M&G braking action turned down a bit to stay well short of any lock-up.
There is no adjustment to 4W disc brakes with antilock. If only one wheel locked suspect Caliper or flex hose?
2000 Pace Arrow M35N F53 V10 Ford  100,000 + miles purrs like a kitten. Yes I am old school.         2007 Honda VTX double dark side

DaveRB55

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Re: Toad Brakes Locking Up
« Reply #24 on: November 03, 2017, 10:51:46 AM »
Firstly, thanks to all of you for your input and support.  I thought I would provide a follow-up on closing this item.

I contacted B&G in Athens (who installed the brake system) and he was a confounded as everyone as to why only one tire burned.  However, he believed the problem was due to over pressurization of the system vs weight of the CRV as Gary mentioned.  Their brake system was initially designed for diesels using the air system.  The power pack that is installed with hydraulic system RV's generates it own air pressure and is fixed around 90 psi.   He promptly sent me a quick disconnect assy with a reducer preset to 80 psi. 

Prior to receiving the reducer I did check for braking consistency without ABS.  Got the car at about 35 mph, switched to neutral and shut the car off, then hit the brakes hard.   No pull on the driver side and the car stopped evenly.  (Pretty tough stopping...didn't remember "no-power" brakes being so hard!).

I also rigged up a quick disconnect pressure gauge that I could install in line both with and without the reducer.   Was getting ~90 psi in line and about 78 psi with the transducer.   On gravel, while towing and hard stopping both front wheels of the CRV locked up.   We then went on the road and my wife drove the RV and hard stopped while I watched from the side.  Without the reducer,  both CRV tires locked up and left about a 12 ft skid mark.   With the reducer, neither locked up.   We repeated the test with me in the CRV and I could definitely feel the CRV braking when the RV hard stopped.  So I think we are in good shape.

No explanation for the single tire burn during the original incident.   Speaking with folks and researching some say it could have been the weight distribution in the CRV,  type of pavement, road conditions, etc. 

In hindsight I was a bit frustrated that B&G did not verify this when the system was installed.  In their defense, he said they had not encountered a single tire lockup like I had experienced.  They did say every install is a bit different with brake system and toad variations.    I must say I was very pleased with their support and product backup.  The were very quick to help, sent me the reducer immediately, and worked with me on the phone several times during testing and explaining how things worked.   Best of all, they are reimbursing me for the ruined tire!  :)   Pretty dang good product support,
   
So that's it...I learned a whole lot more about my brake system and the problem is resolved.  We are still moving towards our goal to RV full time and are working to get our home on the market before the end of the year. 

Thanks again everyone.     
2016 Winnebago Suncruiser
Christened “The Beast”
2010 Honda CRV
M&G Brake system w/Blue Ox Avail

Tom

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Re: Toad Brakes Locking Up
« Reply #25 on: November 03, 2017, 11:13:53 AM »
Thanks for the follow-up. I learn something new every day. M&G is certainly a great company with a great founder/owner.
Tom.  Need help? Click the Help button in the toolbar above.

WILDEBILL308

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Re: Toad Brakes Locking Up
« Reply #26 on: November 03, 2017, 12:10:20 PM »
Thanks for the follow up. Glad it is working now.
Bill
2003 Bounder 38N
300 HP 5.9 Cummins
Allison 3000MH Trans.
Towing 2014 Honda CRV
Home base Fort Worth, Texas
A man who carries a cat by the tail learns something he can learn in no other way.
-Mark Twain-

 

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