Tim Wright Posted July 22, 2018 Share Posted July 22, 2018 (edited) Front tires wanna skid whenever I'm on gravel. Especially if I'm going downhill in reverse. Tire shop guy says brakes look good and he adjusted em. Is there a proportional valve that could be sending too much braking to the front or is it just because there's so much weight in the rear. It's also skidded through an intersection in the rain. I'd be terrified to drive this thing in the snow or a city with steep wet hills. I've talked to another Dolphin owners who said his did it backing out of his garage. I can't imagine this could be normal because it's definitely dangerous. I've been driving it for a few years and it might of gotten slightly better after the alleged adjustment. I really don't know how my girlfriend drive this thing for years and isn't dead. She drives it with no concern and I grew up driving old vehicles without brakes and severely over loaded trucks , run equipment for a living and just know it's not right. Front rotors are slightly pitted with rust. But no wobbles when you brake so I think they're in pretty good shape. Any thoughts would be appreciated. Edited July 22, 2018 by Tim Wright Pronunciation Quote Link to comment Share on other sites More sharing options...
WME Posted July 22, 2018 Share Posted July 22, 2018 Very long winded, but read ALL of this and you will find your answer...http://toyotamotorhome.org/forums/index.php?/topic/4321-brakes-load-sensing-proportional-valve-lspv-and-lspbv/ Basic problem is the brake basis valve is for an empty pickup truck. at best a Toy MH is a grossly overloaded pickup and the rear suspension totally screws up the valve. Quote Link to comment Share on other sites More sharing options...
Tim Wright Posted July 26, 2018 Author Share Posted July 26, 2018 On 7/21/2018 at 11:39 PM, WME said: Very long winded, but read ALL of this and you will find your answer...http://toyotamotorhome.org/forums/index.php?/topic/4321-brakes-load-sensing-proportional-valve-lspv-and-lspbv/ Basic problem is the brake basis valve is for an empty pickup truck. at best a Toy MH is a grossly overloaded pickup and the rear suspension totally screws up the valve. Thanks for your reply. I just assumed there was a preset proportional valve somewhere on the MH. I had no idea it adjusted with the ride height and am gonna have to crawl under there and look at the unit to grasp how it knows where the motor home is sitting on the springs/ride height. As a coincidence I had a guy at the tire place add some air to my airbags the other day. He totally over inflated them rising the camper way up , then let some air out to achieve desired PSI. Shortly after , the first gravel pull off on road with cliff to ocean , it seemed to skid really easy to my surprise. I wondered if it had something to do with adjusting the airbags as my recent brake inspection/ adjustment seemed to of helped with the problem a little. So my question is , are they now set to the height the MH was when he over inflated the airbags or the current height of max pressure for the airbags. It says 90 psi max so that's what I put in. I definitely noticed it was stopping better before the added air. It was as 60 psi before adding the air. If I return to that psi setting will the PV automatically adjust to the new ride height or is it stuck at the height it was overinflated to. Also is 60 psi enough for the airbags or should they be maxed out. Thanks ahead of time for any response , as I've learned so much already about the proportional valve and see hope of this thing stopping better. Quote Link to comment Share on other sites More sharing options...
Derek up North Posted July 26, 2018 Share Posted July 26, 2018 The air springs are designed to level your motorhome, not jack it up like a dragster. Max them out and raising the rear higher than it's designed for will affect handling and quite possible overextend your air springs and rear shocks which will eventually damage them. Quote Link to comment Share on other sites More sharing options...
WME Posted July 26, 2018 Share Posted July 26, 2018 The rear brake valve reacts to the ride height, it does not adjust ride height. The valve is for an Toyota pick not a motor home. When a pickup is empty the rear is up, so the valve sends most of the brake force to the front. When its loaded the rear end sags because of the weight, so the valve sends more force to the rear because there is more traction. Using air bags on a MH totaly messes up the valve. Rasing the rear with the air bags makes the valve think its got an empty pickup so it sends more force to the brakes. The simple answer is to remove the force arm from the rear axle and just bolt it to the frame in the up position, this will give you max rear brakes. works because you have duals (more traction) and a bunch of weight (more traction) Quote Link to comment Share on other sites More sharing options...
DanAatTheCape Posted July 27, 2018 Share Posted July 27, 2018 backing downhill on gravel will lead to locking of the front brakes - I use the parking brake in that scenario -- then front wheels can steer. The front brakes are disc and work wheel - the rear brakes are drum - they also work but as discussed above... designed for a pickup Quote Link to comment Share on other sites More sharing options...
Tim Wright Posted July 29, 2018 Author Share Posted July 29, 2018 On 7/26/2018 at 12:43 PM, WME said: The rear brake valve reacts to the ride height, it does not adjust ride height. The valve is for an Toyota pick not a motor home. When a pickup is empty the rear is up, so the valve sends most of the brake force to the front. When its loaded the rear end sags because of the weight, so the valve sends more force to the rear because there is more traction. Using air bags on a MH totaly messes up the valve. Rasing the rear with the air bags makes the valve think its got an empty pickup so it sends more force to the brakes. The simple answer is to remove the force arm from the rear axle and just bolt it to the frame in the up position, this will give you max rear brakes. works because you have duals (more traction) and a bunch of weight (more traction) Thanks for your reply. Now that I'm beginning to understand how this setup actually works there's hope of this thing actually stopping like it should. Got to get under there and see what position it is in now and where my airbags have it setting. Definitely not gonna max out the airbags any more . Are most RV places aware of this phenomenon ? The tire shop I brought it to has a very experienced mechanic working there and he had no idea about this scenario . I'm probably gonna have someone with knowledge of this situation help me remove the force arm and just bolt if to the frame in the upward position. I definitely think the more brakes in the rear the better. Thanks again. Quote Link to comment Share on other sites More sharing options...
linda s Posted July 30, 2018 Share Posted July 30, 2018 It's an easy fix. Once you see it I'm sure you can handle it. Just adjusting all the way to high didn't do much for me. I know a few people who just left it disconnected from the adjuster and lifted it as far as it would go. Floor of camper or frame not sure. I still need to lift mine more Linda S Quote Link to comment Share on other sites More sharing options...
markwilliam1 Posted July 30, 2018 Share Posted July 30, 2018 I’m with Linda. I disconnected the force arm and tied it to the frame. Unfortunately the brake basis valve didn’t move. Frozen in place! Hopefully over time it will loosen up but I doubt it. Quote Link to comment Share on other sites More sharing options...
BobBeery Posted August 1, 2018 Share Posted August 1, 2018 On my 94 Warrior the valve is already max even with 15-20 lbs of air. I thought it was frozen but tried lowering the force arm and the valve moved freely. As I raised it back up it stopped moving just as I got back to original position. I note that my force arm is not straight. There is a bend in it about three inches from the proportioning valve. The bend causes the valve to behave the same as wiring the force arm to the frame. I don't know if the vehicle came with the arm bent or straight. It is possible that either Winnebago or a previous owner put in that bend. Anyway, I decided that wiring up the arm would accomplish nothing and just re-connected it. Quote Link to comment Share on other sites More sharing options...
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