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Great information Everyone! Will look @ adjusting mine this spring especially after having my rear leafs re- arched and 4 new heavy-duty leafs installed. Really raised up my rear end (not to be sexist Lol!) I never knew anything was adjustable back there....what a Great Forum this is. Thanks!! 

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Well, raising up the rear (either with extra leaves added or air springs) will 'fool' a normally operating valve into 'thinking' you're running like an unloaded pickup and reduce the braking to the rear. That's why it's a good idea to disconnect the rod to the valve and secure it in the fully open position.

 

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So Derek your saying that adjusting the valve fully open is not adequate and I should disconnect the rod completely? Wish I had my rig here but she's in storage till April. I have no clue but do you mean taking off the upper nut and removing the arm completely? How will that secure the valve in a fully open position? Does the valve spring up itself with the arm unattached? PS I won't call you Sir :)!

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Frankly the size of the rear brakes and the weight you can't have too much breaking on the back.

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I totally by passed mine full pressure to the rear brakes and trust me they will not lockup.

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Thanks Derek and Maineah!

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Hi Mark, The way I did mine was to disconnect the control arm at the axle end (where the control adjustment threaded end is). I pulled the one bolt off the arm end allowing me to lift the arm up toward the underside of the floor. where I marked the spot it would come close to. Then I made an "L" shaped bracket and mounted it to the bottom of the cabin floor (under the rig) with hex head self tapping screws. I went inside and found the kitchen table leg holes and measured how deep they were to determine how long a screw to use so it would not stick up into the cabin floor surface. Then I tied the control arm up to the bracket with wire. Huge difference. The problem with air bags is that they raise the rear end so much that even with the control rod set to maximum the valve always thinks the truck has no load at all.

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Thanks Lee & Joan! I don't need air bags as I had my leaf springs rearched and 2 new leaf springs added. Raised my rig about 4 inches. So I'm concerned about the control arm position now. How could you tell the rear brakes are performing better? Not sure how to raise and attach the arm. I'll get Grannie home tomorrow and look. Does the arm need to be completely disconnected or can I just adjust it up as far as I can? Thanks!

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"Moderation is for Monks" just look at things and see what happens when you raise the rod. Then just put a big bend in the middle of it, same result as raising the bar.

As they say in the racing game "too much is almost enough"

Edited by WME

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I'll try that WME. Thanks!

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I don't think there is enough leeway in that bar to bend it much. Just remove it, wire it up to the frame above it and see if it makes the brakes feel better. I saw no difference when adjusted all the way but not removed. I do have my air bags inflated enough to give the back end a lift so maybe that's why. I am going to try removing the bar from the attachment and wiring it up like I suggested. If I like the results then I can figure out a more permanent bracket.

Linda S

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Let us know Linda if you notice a difference please. Thanks!

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How do I know its better? I have yet to get any road miles on it since the fix but I do have a slippery gravel steep driveway. Before the fix I was backing down the slope with the tranny in DRIVE (not reverse) and ready to grab the hand brake because the front wheels would lock up using the foot brake. Now I can back down backwards and actually stop without locking the front brakes.

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That's promising. Not sure how to check if your rear brakes are working properly. Backing down a hill and see if the front brakes lock up or not??

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You see the bracket that is attached to the left side of the differential in the center of this picture? It has a rubber cushioned joint attached to it then a threaded (adjustable) rusty rod sticking almost straight up into a pressed metal bracket with a bolt on each side of the bracket/adjuster rod. Coming in from behind the spare tire and above the axle is a rod (gray) with a little rubber boot on it and the round end of that rod is bolted to the bracket atop the adjuster. The rod end is held there by one bolt threw the round end of the rod. That is the bolt you take out to free the rod end. Then you lift the rod towards the underside of the floor (above & black) to see where to mount your hanger bracket. Then tie the rod end up to your new hanger bracket. Done Deal.

Underside_Rear_Axle_1.JPG

The picture above shows that the adjuster has been placed in the higher (of 2) axle mounting holes and the threaded adjuster is in the highest position threads, the two ways to give maximum increase in rear brake power that Toyota provided. Hanging the rod from the underside of the floor assures you get max rear breaking even with airbags or stiffer spring bundles deployed.

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9 hours ago, linda s said:

I don't think there is enough leeway in that bar to bend it much. Just remove it, wire it up to the frame above it and see if it makes the brakes feel better. I saw no difference when adjusted all the way but not removed. I do have my air bags inflated enough to give the back end a lift so maybe that's why. I am going to try removing the bar from the attachment and wiring it up like I suggested. If I like the results then I can figure out a more permanent bracket.

Linda S

Ya there is enough leeway. If you look at L&Js photo you will see that the axle end of the rod is mounted to a double pivot. Bending is quick and simple. Try it if you like the result then remove the axle end and afix the rod the the chassis. Test the rv brakes on a dirt road BEFORE making the mod and then after. 20 mph should be enough speed

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Thanks All So Much!!

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Road Test: Just took rig to town for two new front "Thunderer" tire and did a lot of foot stomping brake tests. I LIKE IT! Not astoundingly able to stop speeding locomotives with a single bound BUT MUCH BETTER than it was. Tendency to lock front wheels is much diminished, stopping distance is much better. Should be making a road report on the 4:88 rear end changes about this time next week. There is a certain hill getting to my house that is a floor it in first and pray type hill, groaning at 15 MPH.

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Well if some is good, will more be better???

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Hey Lee & Joan, am looking forward to your gear change report. How much it costs and where you got the parts. Having learned I've been driving my rig around in Overdrive the past year what a difference it makes with it turned Off LOL!

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Lee if possible, could you show a picture of your rod adjustment after you disconnected it and tied it up to your frame? I think the picture you posted was before you adjustment? That would be helpful for my un-mechanical mind. Thanks!

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14 hours ago, markwilliam1 said:

Hey Lee & Joan, am looking forward to your gear change report. How much it costs and where you got the parts. Having learned I've been driving my rig around in Overdrive the past year what a difference it makes with it turned Off LOL!

Use the online salvage yard search tool and look for a complete diff assembly near you. I looked for a 1993-95 Toyota 4Runner with 31' tires the rear of which is a 4:88/1 ratio. Found one a couple hundred miles away for $300 + $60 shipping. Prices ranged from 150 for a broken one needing a pinion bearing to 450 with 300-325 being about average.

http://car-part.com/

They are HEAVY so having one shipped adds a LOT to the overall cost

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I went over the mountain to Grants Pass today to get the front end aligned, about 200 miles over the coast range and back. It was raining really hard on the way back.          I must say disconnecting the LSPV was the best performance improvement I have made. I used way less foot pressure on the brake pedal and got way more braking. Something I don't know how to describe is it is a different type of braking, Like the whole rig feels like it hunches or squats down and grabs the road with all 6 tires, somehow. It used to feel like the front end dove a lot but not much braking. I found that my usual paranoid "following distance" decreased quite a bit and I was a lot more relaxed. Anyway it is much improved.

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"The rear end squats" is the perfect description to use when describing the rear brakes doing their fair share.

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Would still love to see a picture of your disconnected LSPV set-up if you have time Lee. Thanks for the report!

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