Need schooling on power output after certain upgrades - HELP!

I took my 80 to a shop and the guy fit new Koni Heavy Track Raids with TJM Extra Heavy Duty Coils that give a 7cm lift, castor kit and new steering damper. He also changed all of the brakes, and removed the factory tires and put on BFGoodrich All-Terrains of the same size (but with the tread I think they add an inch to or two to the diameter). He also changed the fluids, overhauled the axles, and changed all belts (including timing).Upon receiving the ruck yesterday it sure feel likes the truck has less power, and the brakes to don't seem to work as good as the old rusty ones. Before I get paranoid and begin following the train of thought that he swapped out my turbo and gave me crap brakes, I figure I should ask questions about mechanics and physics, etc. With the changes listed above, could I feel perceived losses of engine and braking power? If the tires are bigger, would that require the engine to use more power to turn them? Even if they are marginally larger? I guess a better question would be how big would the tires have to be for me to notice a drop in performance? Gear ratios? What about braking? I guess maybe the lines would have to be longer to reach the calipers now? Could their not be enough fluid, or some other change that has caused the brake performance to suffer. It is all quite noticeable and it began to agitate me to day as I was driving around, plus the rear left brake was sticking yesterday. I hate being without tools and space to work. I hate more not having knowledge. This weird combination has been hard for me to find on the web and forums. Any thoughts?

Knobblier & larger diameter tyres will definately make it feel slower & yes the brakes have less leverage on larger tyres.

Though maybe something is not right, esp if timing has been changed etc

A sticking brake won't help things at all but as mentioned bigger tyres will dull performance.its because the tyre has more leverage to resist the torque of the engine (think of the distance from the center to the Edgar as a lever and you'll see what I mean). The same holds true for the brakes too. Don't forget braking will be worse due to pads not being bedded in to the discs too.

Ok, that makes sense. So, speaking of brakes, as I load this truck up (I am the same guy doing the UK to SA trip) I assume the brake performance will continue to suffer. Do I need to get a heavier braking system?

When you say 'he changed all of the brakes' do you mean he changed the pads or that he overhauled the calipers? If he rebuilt the calipers then nothing should be sticking. If he just changed the pads then you might want to have the calipers rebuilt if one is sticking but make sure someone who knows what they're doing does the work. The parts are quite cheap.

Did he adjust the proportioning valve for the rear brakes? On an 80 there is a load sensing valve that varies how much work the back brakes do depending on load. With the suspension raised and the valve not adjusted there will be very little work being done by the back brakes and they will be rubbish! You'd be surprised how much difference having that valve set right can make.

Your tyres would have to be quite a bit bigger to be noticeable so maybe a pipe got pulled off accidentally would be my guess rather than it being extra tread on new tyres, unless you are mistaken about them being the same size. Tell us what size they are e.g. 275x70x16 and we can tell you if they're the standard size or not.

He overhauled the front and rear calipers, rotors, pads, and the cable assembly controlling the handbrake, etc. Everything is brand new. The proportioning valve is something I'll ask about. I feel like he took care of it as he does a number of overland vehicles for people that have actually gone a few places. All of the ones parked there had uprated suspensions and the place is called LandCruiser Services. Not that it means he knows what he is doing, but they all seemed to be indicators that he did. He could have also forgotten or overlooked it. I'll do a check to see if any pipes are disconnected, though I haven't noticed anything that looks unusual. The tires are 285/75 R16. Thanks for your feedback. I am loving these forums.

Brakes WILL need "bedding in" before they start to work efficiently

Most garages will tell you to take it easy on the brakes for the first couple of hundred miles....steady braking. no heavy stopping, until they are bedded in.

285/75 R16 is a bit bigger than standard but doesn't usually make a great deal of difference to performance.

Thanks, I remember knowing that at some point in my life. I guess my brain is running out of space. Time to flush it and refill it.

Thanks for the tire tip.Good to know.

Jon Wildsmith said:

Did he adjust the proportioning valve for the rear brakes? On an 80 there is a load sensing valve that varies how much work the back brakes do depending on load. With the suspension raised and the valve not adjusted there will be very little work being done by the back brakes and they will be rubbish! You'd be surprised how much difference having that valve set right can make.

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Hi jon, just read your note with some trepidation. New shocks and springs arrived this morning, so just waiting for a dry weekend to swap them out. I didn't know about the proportioning valve, but its clearly important. Where can I read up on how to adjust?

Find a quiet straight bit of road. Clamp of the front brakes. Drive at 15 mph and apply brakes. If nothing happens, your back brakes are not working---bit obvious that---and you need to adjust the proportioning valve rod. When properly set up, the test should see the brakes working but not locking up. Check the ride height before and after the lift and extend the vertical section of the operating arm by the same increase. On my KZJ70, because the load in the back is basically constant, I junked the operating system and converted the valve to manual adjust. The MoT inspector was very impressed with the back brake performance!

Roger

I can't think of a reference just at the minute Andrew but google LSPV. It's pretty simple to adjust and road test, no rocket science involved

Tx Jon, but it seems more complex than I had hoped. Not the actual adjustment, but 'when' to adjust. IIRC, if you stiffen the suspension, when you carry a heavy load it will not affect the LSPV to the same extent, and therefore not increase the pressure to the rear brakes as much as it should. This seems to suggest that it may be necessary to make a manual adjustment to the LSP when fully loaded for an overland trip, as I am fitting the strongest springs available, and then re-correct when back to normal load.

Is there a simple test of braking hard when in reverse to test how much it is actually working? I remember reading it somewhere ...

You can usually find a compromise setting that works well enough for both but in an ideal world some form of adjustment would be best.

Jon Wildsmith said:

You can usually find a compromise setting that works well enough for both but in an ideal world some form of adjustment would be best.

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If you have a limited variation in the load, then converting to a manual adjust system will enable you to fine tune and forget.

If, on the other hand, you have a significant load variation, then the LSPV will work to suit these variations, as long as it is set up in the first place. First make certain that the system is clean and working freely, then "hire" the services of a brake tester at your MoT station and do the adjustment there. You could use paving slabs or similar to load the vehicle to check for efficiency from no load to full load.

Roger

Nice. I'll do that. How has the manual adjust knob been for you? Is you truck fitted with a lot of accessories?

I am in the same situation. The recommendations for my setup are to keep 400lbs of load in the rear. I think once everything is setup I should have more than enough weight to cover that. So apparently this valve and its adjustment are quite important.

CJBNomad8654 said:

Nice. I'll do that. How has the manual adjust knob been for you? Is you truck fitted with a lot of accessories?

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I left the LSPV where it was ie just forward of the back axle. I scrapped the operating rods and fitted an adjuster within the valve. This was relatively simple.Once i had the pressure right, I fitted a rubber cap to seal it and that was that.

Roger