LUVTruck.com

This morning i took the LUV to work. On the way i got in behind a car that was moving somewhat slower than everybody else. I was finally able to get in to the other lane to get around him. I was accelerating up to around 65 when all of a sudden traffic slowed drasticly. I got on the brakes and the rear tires locked up. At least i know that the Ford axle has brakes that function but the 10" drum assy's and the disks up front dont seem to be balanced.
I haven't noticed if any V-8/LUV owners have had to install a proportioning valve to keep the rear from locking up. Any one else having this problem? Will a proportioning valve take care of this or are there better ways to fix this problem.

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Previous setup: 4.1 Buick V-6/TH 350
Current setup: 400 Small Block Chevy V-8/TH 350
9" ford rear end/short bed/blue
What do Water, Electricity and Humans have in common... They all travel the path of least resistance.

I have been thinking of this same problem, but in relation to putting rear discs on my truck at some point. I'll look around and see what I can find, but if anyone knows some good links to brake upgrade general theory and suggestions please post them. I think it would be a big help to have some good how-to resources for balancing front/rear brake performance and general info on beefing up the braking system.

Wouldn't rear disks make the the problem worse? The way i see it, motor weight drives down on the front end and the rear gets very light. And being a small truck there's not much weight in the rear to start with. There needs to be more braking action up front and less in the rear. Installing disk brakes on the rear would only magnify the problem. They would lock up even easier. By reducing the action in the rear the front will have to handle most of the load. As long as the rear brakes react first before the front, there shouldn't be a problem.
This is how i was schooled about brakes, If there's better info out there, i'd like to hear it.

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Previous setup: 4.1 Buick V-6/TH 350
Current setup: 400 Small Block Chevy V-8/TH 350
9" ford rear end/short bed/blue
What do Water, Electricity and Humans have in common... They all travel the path of least resistance.

Well, disk brakes do offer more stopping power, but they also seem to be easier to control.

This is just from experience, but my 75 has drum all the way around. In that truck, the brakes are "touchy". In other words, x amount of pedal pressure stops quickly, x+1 amount of pedal pressure locks up the back tires.

With the disc, they seem more controllable. My 76 has disc all the way around. In that truck, the brakes are smooth. For example, x amount of pedal pressure stops the truck quickly, x+1 amount and the tires start chirping and barking, x+2 and the tires start squealing here and there, etc. Eventually at x+5 pedal pressure and you've locked up all 4.

I guess another way to explain it is to say that drums brakes seems to be all or nothing in comparison to disc.

Yet another way to put it, I can't remember the last time I locked up the back brakes on the 76 and I don't have a proportioning valve. On the 75 I manage to lock up a rear tire or two almost weekly.

Drum brakes are 'regenerative'. That means, as the shoe presses against the drum, the twisting action actually causes it to press harder. This makes them a bit harder to modulate.

Disk brakes are linear. More pressure equals more stopping, thus they modulate better. They also require more pressure, which is why all disk brakes are power assisted.

All cars have proportioning valves, because the front brakes get proportionally more stopping force than the rear. This is particularly important on front disk/rear drum cars because drums and disks require vastly different pressures.

The few Luvs I've driven, including mine, will lock the rear brakes easily. I think they are adjusted that way so the truck will stop if you've got a half ton of junk in the back.

I've heard of, but never tried, adjustable proportioning valves that let you set the front/rear proportions. I had planned to put one in my Luv, but now I'm doing something different.

I'm currently putting a Trooper 12 bolt differential in my Luv. I got the hub-to-hub assembly, complete with disk brakes. I'm going to try it first with my existing master cylinder and proportioning valve. If I don't like that, I'll put the trooper ones in, assuming they've been set for disk/disk. When I get it done (sometime in the next couple of weeks) I'll let you know.

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You went there in that?!?!

Front brakes do around 65% of your braking. In wirking on my brother in laws Jeep Cheeroke truck it has a valve on the rear axle that has a bracket that goes to the bed frame. This valve is tied into the brak system and adjusts the amount the rear brakes work according to the load in the bed of the truck. These were put on a lot of trucks, full size, this was the first smaller truck I have seen this on.

I don't see why you could not fit oe of these to your Luv and 9 in rear.
A regular prop valve doesnt adjust for load. Either one should help.
HTH
Richard

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75 Luv, 350 V8, TH350, Camaro rearend. New 1975 Luv Step side. Stock for now.
Grandmaster of the "Shade Tree" way.. I can't see the yard for all the cars. Come on down and we will sit on the porch and watch the grass grow.

I have a similar problem as blue meanie. I got the 75 LUV with a v 8 allready in it the rear end is suppose to be out of a nissan. The first time I drove the truck it didnt want to stop at all and if you stood on the pedal with your ass off the seat the rear tires would lock up. Now I have installed discs from a 78 on the front. Now it will stop hard enough to put your face in the windshield. The rear tires dont lock up anymore or havent yet anyway but the rear brakes are so tight it takes an act of god to do a brake stand most of the time it wont. Does anyone know anything about nissan rear ends? I dont know whats in mine it kind of looks like a smaller version of the ford 9'' I have looked every where on the web for any discriptions but im still coming up empty handed.