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Upex

450h any surprises with changing brake pads and disks

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All,

I'm due to be changing all disks and pads, alongside the track rod ends, rear shocks and sorting something regards the exhaust, plus a full service inckuding plugs, and am tight on time to get it all done before mot expires.

I therefore went looking for anything I should know of in advance, regards the changing of the brakes, as never touched a hybrid brakes before and keen for no surpriseses that slow me down.

Is there anything I should know before starting, as the regen braking is playing on my mind. Perhaps winding the piston back is also different to most, or other such stuff.

Lastly, anyone know where I can find torque specs, specifically for the brakes, ie carrier bolts, wheel studs and the rear suspension bolts that I'll be undoing when changing shocks? Like to do stuff as per, where possible, but can't find torque specs anywhere.

Thanks

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This is a well timed query as also I'm planning to get all my brakes refreshed soon.

The rear brakes have the handbrake nestled inside the disk bells, using shoes #oldskool Which I've not come across before. But it seems you just line up the bell access hole with the shoes adjuster and knock it off to release the disk.

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I changed my disks and pads a while ago.

When I removed the rear disks, I thought the hand brake shoes were looking a little thin, so I ordered new. When they arrived, the new ones looked the same.

Both rear calipers were seized, which is a common fault. Care should be taken when bleeding because the pedal doesn't go down to the floor, it's electronic. By the time you've realised whats happening, all the fluid is in the jar. :)

But if you don't encounter those problems, the task is no different to any other car. 

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If they are anything like the RX400h make sure your key fob is nowhere near the car or the brakes will prime any you won't be able to push the pistons back to get the new pads in.

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Good shout about key, nut not planning on changing fluid now, just the pads and disks. Will be getting fluid done in a little while once mot passed.

To release the rear handbrake shoes, is it a clockwise or counterclockwise turn on the adjuster, and is it the same on both sides? Had a few mares with these in the past, by not knowing which way to turn the bloody things.

Also, anyone got a clue regards torque specs, keen to not knackar my new rear struts!

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I imagine turning the adjuster a click or two will either free up or lock up the brake disk.

That'll be a good hint.

But I take your point and will try to look it up later.

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11 hours ago, Farqui said:

This is a well timed query as also I'm planning to get all my brakes refreshed soon.

The rear brakes have the handbrake nestled inside the disk bells, using shoes #oldskool Which I've not come across before. But it seems you just line up the bell access hole with the shoes adjuster and knock it off to release the disk.

@Farqui Farqui IF the rear set up is the same as the is-F there are some great instructional vids on utube how to do it in stages.

Big Rat

 

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13 hours ago, Upex said:

All,

I'm due to be changing all disks and pads, alongside the track rod ends, rear shocks and sorting something regards the exhaust, plus a full service inckuding plugs, and am tight on time to get it all done before mot expires.

I therefore went looking for anything I should know of in advance, regards the changing of the brakes, as never touched a hybrid brakes before and keen for no surpriseses that slow me down.

Is there anything I should know before starting, as the regen braking is playing on my mind. Perhaps winding the piston back is also different to most, or other such stuff.

Lastly, anyone know where I can find torque specs, specifically for the brakes, ie carrier bolts, wheel studs and the rear suspension bolts that I'll be undoing when changing shocks? Like to do stuff as per, where possible, but can't find torque specs anywhere.

Thanks

Robert.

Torque settings for wheels, brakes, and shock fitting.

Wheel nuts 76 ft/lbs

Front Brakes:-

Caliper bolts 58 ft/lbs

Rear Brakes :-

Caliper bracket bolts 40 ft/lbs

Slide pins 18 ft/lbs.

Shock absorber mountings:-

Front shock top nut 21 ft/lbs

Top ball joint nut 64 ft/lbs

Bottom shock through bolt 81 ft/lbs tighten bolt holding nut still with suspension loaded.

Height sensor nut 48 inch/lbs 

Rear shocks :-

Top shock nut 13 ft/lbs

Bottom shock through bolt 81 ft/lbs tighten bolt holding nut still with suspension loaded.

Bottom arm to hub through bolt 81 ft/lbs tighten bolt holding nut still.

John.

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The brakes on the GS450H along with many of Toyota hybrid cars cannot be bled properly without Techstreem or a suitable service tool. It also requires the removal of the two ABS motor relays.

Failing to do this can mean the loss of fingers as it is possible for the brake system to pressurise without the key fob being in proximity to the car. Opening the drivers door can initiate pressurisation. If this happens with pads removed the caliper pistons can be pushed out resulting in loss of fluid, and air entry. You have been warned.

John.

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Looks like I should rethink painting the calipers with no pads/disc's in place then.

Or at least take precautions!

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7 minutes ago, Farqui said:

Looks like I should rethink painting the calipers with no pads/disc's in place then.

Or at least take precautions!

Disconnecting the battery then operating the brake pedal till it goes hard will remove all the pressure in the accumulator. It will also discharge the emergency capacitor battery backup for the accumulator pump making things safe to work on. Putting hardwood blocks in place of the pads can be an alternative, but not recommended.

If it is required to bleed the brakes the two abs relays must be removed, and Tecstream or similar connected to open various valves in the hydraulic system.

John

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Thanks for all the inputs folks.

John, haven't a clue where you found the torque settings, but very much appreciated now by me, and I'm sure many others in the future. I like the peace of mind they give, when I know I'm not likely to lose a bolt or break a bolt when steaming down the road!

Interesting comments regards the brake system. Will do the battery disconnect and pump thing, as have an accumulator issue anyway, so that may kill or cure, and save my fingers! Why design such a complicated braking system, it's beyond me, but there you go.

Will bleed at a later date, have techstream, just need to build a power solution for my laptop, as only lasts about half hour as battery knackard and i have no power in my garage! Lifes never as easy as it should be eh!

Cheers all

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2 hours ago, Upex said:

Thanks for all the inputs folks.

John, haven't a clue where you found the torque settings, but very much appreciated now by me, and I'm sure many others in the future. I like the peace of mind they give, when I know I'm not likely to lose a bolt or break a bolt when steaming down the road!

Interesting comments regards the brake system. Will do the battery disconnect and pump thing, as have an accumulator issue anyway, so that may kill or cure, and save my fingers! Why design such a complicated braking system, it's beyond me, but there you go.

Will bleed at a later date, have techstream, just need to build a power solution for my laptop, as only lasts about half hour as battery knackard and i have no power in my garage! Lifes never as easy as it should be eh!

Cheers all

The brake system is complicated because it cannot use a servo running from the inlet manifold depression as the engine at any one time may not be running. Further the hydraulic brakes are not used all the time when braking. Regen braking being used instead to save the energy "controlled by the foot brake pedal" that would be normally thrown away. So the system has to have a brake simulator built in to the mechanism.

For your laptop Maplins do a cigarette lighter plug in adapter with various voltage outputs, and plugs to power laptops from the car or a 12 volt car battery. Alternatively New laptop batteries can be bought on Ebay for around £10 depending on the model.

If you need any other torque settings for the car let me know, and I will do my best to find them.

John

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The info in this thread should be made into a sticky thread and/or How To guide.

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When I changed my rear calipers I bled my brakes without the aid of Tech Steam. Once I'd sussed that the pedal wasn't going to react in the normal way, I just used a tube with non return valve on the brake nipple and touched the pedal so the pump runs. I Kept filling the reservoir because fluid flows at a fast rate.

The car has been serviced and MOTd by Lexus twice since, with no problem.

 

I know this is not the recommended way and maybe I got lucky but I never even considered there could be a problem, in those early days of ownership. :)

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4 hours ago, AmbroseJohn said:

When I changed my rear calipers I bled my brakes without the aid of Tech Steam. Once I'd sussed that the pedal wasn't going to react in the normal way, I just used a tube with non return valve on the brake nipple and touched the pedal so the pump runs. I Kept filling the reservoir because fluid flows at a fast rate.

The car has been serviced and MOTd by Lexus twice since, with no problem.

 

I know this is not the recommended way and maybe I got lucky but I never even considered there could be a problem, in those early days of ownership. :)

John.

You can sometimes get away with the way you bled the brakes. The problem arises when for some reason the system has been emptied of fluid "changing the brake actuator". There are then lines and solenoids that cannot be cleared of air because the solenoids remain closed unless they are opened by Techstream.

I learned the hard way when working on a Prius. I did not injure myself, but I got sprayed with brake fluid including my eyes "that stuff stings", and had to rebuild a rear brake  caliper.

Below is the hydraulic circuit of the Prius braking system. I have every reason to believe the GS450H is very similar. It also shows why it is required to use Techstream or similar to clear all the lines of air, and old fluid when doing a fluid change. Note there are 7 pressure sensors, and 10 solenoids electrically operated.

It also shows how fluid under high pressure from the hydraulic accumulator can find it's way to the calipers without the brakes being operated manually. This is required for the VSC, and distance control braking effects. The car also does a line pressure check as part of the system check before the car is started. 

brake-map-jpg.35814

John.

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Some additions to the torque settings.

Front lower steering knuckle ball joints 2 holding bolts 89 ft/lbs.

Ball joint nuts 64 ft/lbs then turn (tighten) till cotter hole align max 60 degrees.

John.

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57 minutes ago, Britprius said:

John.

You can sometimes get away with the way you bled the brakes. The problem arises when for some reason the system has been emptied of fluid "changing the brake actuator". There are then lines and solenoids that cannot be cleared of air because the solenoids remain closed unless they are opened by Techstream.

 

John.

Looks like I really did get lucky, especially as, by the time I realised what was happening with the pedal, the reservoir was completely empty. Maybe the amount of air entering the system from the reservoir end, was not sufficient to empty the valves you mention.

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On 10/2/2017 at 6:49 AM, Upex said:

All,

I'm due to be changing all disks and pads, alongside the track rod ends, rear shocks and sorting something regards the exhaust, plus a full service inckuding plugs, and am tight on time to get it all done before mot expires.

I therefore went looking for anything I should know of in advance, regards the changing of the brakes, as never touched a hybrid brakes before and keen for no surpriseses that slow me down.

Is there anything I should know before starting, as the regen braking is playing on my mind. Perhaps winding the piston back is also different to most, or other such stuff.

Lastly, anyone know where I can find torque specs, specifically for the brakes, ie carrier bolts, wheel studs and the rear suspension bolts that I'll be undoing when changing shocks? Like to do stuff as per, where possible, but can't find torque specs anywhere.

Thanks

Robert I should have said in my previous post you can just push the pistons back in the normal way when fitting new pads. At bar minimum though before doing anything disconnect the battery and operate the brake pedal till it goes hard. The manual says to pull the 2 ABS relays, but without power, and no pressure in the accumulator reservoir you will be safe.

After fitting the new pads operate the brake pedal again to push the pads up to the discs. Do this before connecting the battery as otherwise it can trigger a brake fault code. This is not critical for you as you have Techstream to clear the code.

John

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Cheers John, for info, guidance and torque info.

Here's hoping I get the bits in time and it's an uneventful job lol

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So rear shocks changed and the old one must not have been bad, as made no difference lol, expensive fix for an mot sheet and no improvement lol.

I did balls up though, didn't fit the next rubber bits at top. Were in bottom of box and didn't see until done. I reused the existing ones (the black rubber bits that sit on top of the yellow thing on top of the strut). Will this be ok, or should I take them off again to refit those bits?

John your instructions were spot on. I printed them and referred to them for first one, but after that all ok. Thank you for providing them and the torque settings, very much appreciated.

I however didn't have the same ease you reported. The lower shock bolt and the lower bolt between arm and hub had been put on by the hulk. It broke my 2 foot breaker (not far off new, not knackard with use) and went a long way toward almost breaking my 4 ft breaker. They were very corroded, took me half hour per bolt to get them usable again (they are still sturdy, it was just surface etc, but was proper blocked in etc). My suggestion for others doing this is to get some spare bolts just in case they are like mine.

Changed the rear disks and pads whilst at it, and gave calipers, hub and wheels a good clean up, on the mating surfaces. Amazes me that shops just put wheels on with all the crap on the hub etc, and wonder why breaks shudder and the like.

Now to sort the ceased front caliper, then change front disks and pads and that should be mot ready. Plus a full service, then should be good to go.

Thanks again for the help John, been a star, yet again!

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Well done replacing the shocks and brakes, unfortunate that you found all the parts once the job was completed tho #doh

Did the footbrake shoes and adjuster give you any trouble? Was the adjuster easy to free off each side?

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No trouble. Disks were stuck to hub, why do folks not put anticeise on?, so had to hit them off with lump hammer and wood, but the brakes didn't catch at all, didn't need to use the adjuster. However, the rear disks were not old, not worn much at all, so there was no lip to catch on etc.

Yeah, doh with bits. Hopefully John will say it doesnt matter and I can sleep easy. Don't fancy taking them out again to that one bit lol.

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Robert I should have pointed out those bottom through bolts are very tight, and contrary to normal thinking you undo the bolt holding the nut stationary "sorry". The same goes when torquing them up the nut is held still, and the bolt torqued. I did point this out in my torque figures. They are however very substantial high tensile bolts.

I use a 12 volt cigar lighter plug in impact wheel gun to undo mine as I do not have a compressor. These are about £35 on Ebay complete in plastic case with 4 sizes of impact sockets. Worth every penny as it makes wheel changing effortless when just bending down is a problem. I carry it around in my boot held to the drivers side  by the strap fitted possibly for a first aid box.

Not fitting the new top shaft rubbers will make little or no difference. The yellow rubber is the bump stop The shocks can loose quite a quantity of oil before they stop working, but usually start to make a knock on longer travel strokes as the rod piston comes into contact with the gas separation piston that rises in the shock tube as oil is lost. 

For the calipers I would ring "Biggred" first thing Monday to get things moving quickly. They have been very efficient in the past when I have used them.

John. 

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Thanks John, I'll save redoing the rubber tops then, result lol.

I'll be on to big red, no worries there.

Your instructions were spot on. I noted the bit about the nut and bolt, and to be honest, I normally turn the bolt, vs nut anyway, they were just stuck in there as had swollen with rust, especially on the unused threads. 

I did not though that the rear slide pin rubbers are both broken, badly. Thankfully, the grease in there was still present and albeit a bit grungy, they were saved, but I do need to get new ones. Anyone know where or what I'm looking for? Part pics I've found don't show them!

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