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Brake overhaul, including caliper rebuild

chadr

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england
After our recent trip to France, I've come to the conclusion that I really need to get the brakes overhauled on the truck before we go to Scotland/Highlands at the end of October.

Whilst the brakes do work....eventually, for anyone not familiar with the truck it can be quite disconcerting; for the first few inches of pedal travel, nothing much happens at all, the braking effect is negligible. All the action seems to happen in the last couple of inches of pedal travel. Even then it always *feels* like the fronts are doing all the work and the braking isn't even (I know the fronts do do most of the braking but it doesn't normally *feel* like that - it's a bit like stopping a bike just with the front brakes).

Last year I had the fluid changed and Goodyear braided hoses installed all round. Though that did little or nothing to improve things. The current discs and pads are about 35k mile old, so the pads may certainly be on their way out. I have already sourced OEM pads for front/rear from Simon Holton in readiness. The discs should still be OK, though I'm happy to change these too if you think it will help.

However what I would really like to do is to give the whole braking system a complete overhaul - i.e. rebuild the calipers all round and pay some attention to the LSPV, which hasn't been touched since my 40mm lift.

Do you think a local brake specialist would OK for this? I'm sure it's a relatively simple job, though I have always been dissapointed when I've taken my truck to the local "specialists". Ideally I'd be tempted to take the truck to someone like Julian V even though it's 100miles away and get some other bits and pieces looked at at the same time.........I have sent him a message via the form on his site a few days ago but not had a reply just yet.

Appreciate your thoughts on this....Thanks.
 
IMO garages , even specialists , will just take everything off and blast it clean with a pressure washer then tell with a smile things should be 100% better now as they hand you a ludicrously large bill for something you could have done yourself without much effort . Why not get hold of any old caliper and have a go at stripping , cleaning and rebuilding it . Likelihood is once you have you won't even consider paying someone to do your truck .
 
Did you adjust the LSPV when you fitted the suspension? If not, that's like to be the main culprit - the symptoms sound similar to those I experienced.
 
@ Shayne - Yes, I'm sure with a little bit of guidance, I could attempt this job myself. The problem is that it is also my daily driver and family transport. So ideally I like to schedule any work, so I can arrange alternatives and am not left without wheels.

@ Doodle - No I haven't adjusted the LSPV, though TBH I'm not even sure mine is working.......I have a feeling it maybe seized? It's certainly on the list to be looked at.
 
I have the same problem Chadr as i use my truck daily , that's why i suggested trying your hand at refurbishing a spare , that's what i would do so i could work out how long it would actually take me . Possibly i would end up doing 1 caliper a time so i wouldn't be without my truck for more than a few hours . It doesn't have to be a landcruiser caliper they are all the same in principal .
 
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Thanks Shayne - I have bookmarked that! :)

The adjustment and bleed nipples etc. on the LSPV are certainly seized solid and look like they have never been touched in the truck's lifetime - so it probably hasn't been bleed either. I think I would have to cut the existing mechanism off and weld/bolt a new one on......
 
I didn't bother bleeding mine, but i had to cut off and recreate the mounting point.
 
Perhaps i should be thinking about this as my truck now stands about 6ft 6" tall ? I'm happy with the brakes though so i'm not sure i have anything to gain :think: let sleeping dogs lie i reckon :eusa-shhh:
 
Checking the LSPV is easy.

Find a straight, quiet stretch of road. Clamp off the front brakes. Accelerate up to 15 mph and apply footbrake. If nothing, or very little happens, stop using h/brake. Frightening isn't it:shock:

What should have happened is the rear brakes nearly locking up. To rectify, you need to lengthen the vertical arm that comes off the axle. 50 mm lift = 50 mm extension. Make it adjustable so that you can fine tune it. Lengthen it and you increase pressure to back brakes, shorten it brings the opposite.

The lack of response from the brakes on initial pushing the pedal is possibly the clearance between the booster push rod---that's the rod that the brake pedal pushes into the booster---and the booster itself. Clamp off all the brake hoses. Without the engine running, push on the pedal. Pedal movement should be solid after approx. 20 mm. If it feels soggy or spongy I suggest you bleed the brakes---how old is the brake fluid, what colour is it---and try again. If pedal feels solid but not until pedal is pushed further, then adjust booster push rod. On the 70 series the rod has adjustment built in. If it's the same, the rod has a threaded section for the purpose. Adjust until there is some clearance as you apply the brake.

To check the calipers, you need to remove the wheels and the pads and see if the pistons move freely. If not, they will need re-building.

Roger
 
Thanks for that detailed reply Roger.

The brake fluid was changed almost exactly a year/8k ago. The fluid in the reservoir looks brand new........

I'll hopefully have a play with the LSPV over the weekend and see if there are any improvements. I'll check out whether there is a booster rod adjustment too.
 
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What should have happened is the rear brakes nearly locking up. To rectify, you need to lengthen the vertical arm that comes off the axle. 50 mm lift = 50 mm extension. Make it adjustable so that you can fine tune it. Lengthen it and you increase pressure to back brakes, shorten it brings the opposite.

On the 90 the LSPV is attached between body and panhard rod, so a direct 1:1 ratio would be far too much. It's probably 2:1 at least in terms of lift:extension.
 
On the 90 the LSPV is attached between body and panhard rod, so a direct 1:1 ratio would be far too much. It's probably 2:1 at least in terms of lift:extension.

There will be a near horizontal rod between the valve and the panhard rod. The idea is to maintain the same angle as this rod attaches to the valve in the before the suspension lift as to after the lift. There has to be some form of adjustment in the original set-up to accommadate fine tuning at the factory.

As my 70 series does not have rear seats, the loading in the back stays relatively constant, so I took the opportunity to remove the LSPV adjustment system and convert the valve to manual adjustment.

Roger
 
Well I had a look at the LSPV and did a little experimentation with it this afternoon. With the current set-up, the tension on the spring and its nearly horizontal angle, means that the rod is at its highest point, closest the body. So presumably the valve is "shut" at that point with negligible brake force going to the rear.

The adjustment mechanism was way too rusted to even try undoing it, so I experimented by pulling the rod down to its lowest point and secured it with a cable tie. Took the truck for the drive round the block and you can certainly feel the rear brakes working. The pedal feel and pressure is a lot better, though there is still room for improvement IMHO in that area. The overall "feel" of the truck under braking is much better, though as to be expected, a little too rear biased for everyday.

So I think my first step is try and sort out the adjustment mechanism and find get the LSPV back doing its job. Once that is sorted, I'm sure that the brakes will be much better. I can then sort out a overhaul at my leisure in the coming months.

As you can see, the angle of the LSPV spring is horizontal......
20130831_183514.jpg

The state of the adjustment mechanism.....
20130831_183547.jpg

Thanks for all your help. :thumbup:
 
Hey Chad, happy to help you with the caliper rebuild when you come to it. Should not take too long as long as you get a seal kit and prob 2 spare pistons, which if we don't use we may be able to return them to Simon. I found on Lil Blue and my 120 I needed to replace both lower pistons on both sides as they were badly corroded
 
Thanks for the kind offer Tony - much appreciated.

I'll try and get the LSPV sorted out over the next couple of weeks and then see how things go.......
 
There will be a near horizontal rod between the valve and the panhard rod. The idea is to maintain the same angle as this rod attaches to the valve in the before the suspension lift as to after the lift. There has to be some form of adjustment in the original set-up to accommadate fine tuning at the factory.

As my 70 series does not have rear seats, the loading in the back stays relatively constant, so I took the opportunity to remove the LSPV adjustment system and convert the valve to manual adjustment.

Roger

Yes Roger, but what's that got to do with the point I made that it's not a direct 1:1 ratio? The adjustment is on the panhard rod, and because this is moving at an angle to the vertical, the amount of movement caused by the suspension lift is not the same as the amount of lift itself. To accomodate a 50mm lift, you're only needing to move the LSPV 25-30mm to compensate.
 
Yes Roger, but what's that got to do with the point I made that it's not a direct 1:1 ratio? The adjustment is on the panhard rod, and because this is moving at an angle to the vertical, the amount of movement caused by the suspension lift is not the same as the amount of lift itself. To accomodate a 50mm lift, you're only needing to move the LSPV 25-30mm to compensate.

Nothing at all, except that you need to add the info. that you gave to the info I gave to arrive at the point that the valve operating arm needs to be adjusted back to the same angle that it was before the suspension lift.

Chadr has already carried out an experiment that shows that it is the valve that is the problem. It's now a matter of figuring out how to carry out a permanent adjustment.

I wasn't knocking your input, just advising the situation that we have on the 70 Series. I wasn't aware of the difference in the set-up, as the way to sort it is the same anyway.

Roger
 
I've only breezed over this thred quickly but here goes.
To get the adjustment correct on the load sensing valve you need to fit a pressure guage to the valve according to the load in the vehicle. Easiest done with an empty boot and fuel tank.
There is a sticker on the vehicle I think its in the drivers door shut, giving the correct pressure you should be getting.
Main dealers will have this tool.
 
I've only breezed over this thred quickly but here goes.
To get the adjustment correct on the load sensing valve you need to fit a pressure guage to the valve according to the load in the vehicle. Easiest done with an empty boot and fuel tank.
There is a sticker on the vehicle I think its in the drivers door shut, giving the correct pressure you should be getting.
Main dealers will have this tool.

There are a number of problems with this.

Main dealers don't like working on vehicles of this age. They know that there will be numerous problems relating to general wear and corrosion that are difficult to foresee, evaluate and cost.The seized bleed nipples on the LSPV are a case in point.

If they did agree to look at it, they would hit the snag of the raised suspension. The standard set-up can't accommodate the necessary adjustment and as soon as the dealer realises this, he will stop work, as he wont want (a) to be held responsible for work on a non standard vehicle and (b) he wouldn't be allowed, by Toyota GB, to modify a vehicle outside Toyota spec.

But lets just imagine he agrees to do it. This will be based on time spent on the motor. He will not bother with a quote. It will be £100 per hour plus parts, and that includes parts that they have broken.

You will be looking at a bill for £300 plus.

Or you could modify the linkage to compensate for the lift. If you make the modification adjustable and road tests are positive, a back hander to your MoT tester would see you with some brake efficiency figures and his view as to how they look.

Roger
 
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