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How To:- Refurbish the Rear Brake Calipers

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How to refurbish your Mk1 rear brake calipers

Written by: MonkeyMax

This is a guide on how to refurbish your rear brake calipers using the refurb kits available from either Toyota or Brakes International. It may not be the ideal method, but it works for me and for others who have tried it!

* A refurb kit. Choice of:
Toyota (Part number: 04479-17011 , £50.56 + VAT at time of writing, one kit for two calipers)
Brakes International (P/N: BCK3613 , £19.85 at time of writing, one kit for one brake caliper, £6 next day delivery charge)
Possibly others, but these are the only ones I've investigated and covered in this document.

* Possibly pistons depending on the state of yours; more details in the document:
Toyota Part number: 47701-17010 , cost of £45.99 each plus VAT at time of writing (I'd recommend you purchase if required after inspecting yours)

* Possibly replacement bleed nipples... should you need to buy new bleed nipples, they are the same as the front caliper bleed nipple from the 1990-2000 MR2.

* New Caliper bolts, available from Toyota (part number 90119-08431 , cost 78p each plus VAT at time of writing) (not strictly necessary, but at that price, well worth replacing!)

* 21mm deep socket for wheel-nuts

* 17mm socket if you're removing the brake caliper carrier (not necessarily the case)

* 14mm socket to remove the bolt holding the caliper in place (necessary)

* 8mm spanner for bleed nipples (note, depending on level of corrosion, 7 or 6mm spanner may be more useful!)

* Torque wrench

* Suitable Jack and Axle stands

* At least 1/2 Litre of new Brake Fluid (though a 1L bottle will definitely see you through, and would be good if you need to flush the entire system) - I use DOT5, though for road use DOT4 should be okay.

* 30 minutes or so per caliper if you just do the refurb... Allow more time for photos/tea/consulting the web/spraying the rust penetration spray - especially if you're removing the caliper...

* Patience

      Items required:

    * A dictionary of new curse words - as you'll probably work your way through it quite quickly given how fiddly this job can be!

Please read this entire guide through before starting, if you've never done this job before! If you have any questions - just ask!

Another recommended read: CLICKY

Safety information: You will have to lift the car off the ground and remove the wheel you're working on. Obviously as the car will be lifted for a while, ensure that the car is secure before you remove the wheel and is supported by axle stands, not just a jack. Always remember - safety first!!!
I would also recommend wearing gloves and safety glasses - at the very least while removing the caliper. Brake fluid can be nasty and there's a risk of it spurting about if you're not careful. Additionally, brake fluid is corrosive and can damage the cars paintwork. If any is spilt on paint, wipe it off as soon as you can. What's more, I recommend putting a bucket or something similar underneath where you are working as Brake fluid has been known to damage Tarmac as well! (At around 80p for a Tesco Value bucket, there's not really much excuse!) Lastly, if you sand anything down, or use a wire brush to clean off the caliper (as I had to do), please wear a face mask and goggles! It's a very messy, dusty job!

Disclaimer: I take no responsibility for any damage, harm, injury or death that can occur to you, your car or your drive (or other surroundings) while carrying out this job. Any mistakes made are yours. (But if you have common sense you should be fine - this is a fairly simple job really)
Additionally, I am in no way affiliated with either company mentioned in this article, nor am I an expert in the field of brakes. I'm merely an enthusiast passing on his knowledge...

Right, with that out the way...

This is a guide on how to recondition/refurb your rear brake calipers. The process is similar for the front brakes. It is based on a refurb kit I purchased from Brakes International (check the discounts section for the members discount).
The part number from them for the refurb kit is BCK3613. You will need one per caliper - that is, two per axle (or per car, seeing as they are specific for the rear calipers).
Alternatively you can purchase a refurb kit from Toyota, they cost £50.56 + vat,at the time of writing this, were I to do this again, it's the one I'd go for.
The part number for the kit from Toyota is 04479-17011. The Toyota kit provides the seals you need for one axle - that is, one kit does two calipers...

I did this with the caliper off the car. This makes the refurb procedure much easier, but it does mean that you have to remove the caliper, plug up the hose somehow (without damaging it) and then bleed the brakes again when you reattach the caliper.
I knew that I was going to completely flush out the brake fluid when I was doing this, so when I removed the pipe I just let the fluid drain into a bottle. Bear in mind that there is still going to be fluid inside the caliper, so be prepared for a bit of fluid to come out of it while moving it around!
If you do this job in situ, it's going to be slightly more complicated and a lot more cramped! If this is the case, be prepared to swear a lot as it'll require a lot of patience and persistence!
The procedures are slightly different depending on whether this is being done with the caliper still on the car or off the car. I've tried to describe it as generically as possible, but there may be some differences between the two.

Step 1:
Remove the wheel, as per usual methods and ensuring everything is safe - car is well supported on axle stands, etc. You'll need a 21mm deep socket to undo the standard wheel-nuts.

Now, with the wheel removed, you have to undo the bolt shown in the diagram below with the green circle, and swivel the caliper around on the slider at the top (in blue)
Removing this bolt sounds simple, but be careful. Have the rust penetrating spray handy! I had one of these bolts shear on me! When this happened I removed the entire carrier/caliper assembly from the wheel and purchased another one (second-hand, of course) which then replaced it. In order to sort out the original caliper, I had to drill and then retap the hole where the bolt had gone.
Should you need to order a replacement bolt, I paid 78p (+ VAT) for a new one (I bought 4) from Toyota. Part number: 90119-08431 .



Step 3:
Remove the handbrake cable (this is attached with a pin going through the lever marked in green in the following photos. The pin is, in turn, secured by a split pin underneath it).





Step 4a:
If you are going to do the job in situ, lift the caliper up as shown, and using a cable tie or two, hang it off the bracket for the brake hose just above it, or the suspension:



Step 4b:
If you are removing the caliper, undo the hoses to the caliper (remembering to catch the brake fluid that would drain out!).
You can clamp the brake pipe flexi-hose with mole grips, but be careful not to crush the pipe!
An alternative is to get a rubber glove and put the pipe into one of the fingers in the glove. Then, use a rubber band to hold the end of the glove finger tight against the end of the pipe (where the 'tap' is). You will still lose some fluid but this will hold most of it!
Another method is to place a bit of tubing over the brake pipe union bolt - 8mm should do the trick and can be packed out with a couple of layers of rubber tape to help prevent further drips.
Then lift the caliper and slide it off the car (in the direction out of the car).


Examining the Handbrake pull on the piston
Now that you've got the piston exposed, it is a good time to just quickly check your handbrake. The lever marked in green in the previous photo is the handbrake lever.
When operated it should move in a direction towards the front of the car. Push the lever now (it will require some force) and hopefully you should see the piston come out by a millimetre or two.
You could also check the cable by putting a screwdriver through the cable end (It has a metal bracket with two holes - one on top of the other... put the screwdriver through the holes) and having a friend lift the handbrake lever. The cable should pull inwards towards the car...

Now back to normal service...

Step 5:
This is what my caliper looked like upon removal:



Were I to paint my caliper, this is probably the point in the process at which I'd do it. Just be careful that there is no brake fluid left inside the caliper before you do paint it though! The process of painting a caliper is going to be left for another article.


Step 6:
I really recommend as a first job that you test your bleed nipple. Make sure it can be loosened/removed as you'll probably need to bleed the brakes afterwards - last thing you want is to do the refurb (costing you the money for the seal kit) only to find that you can't bleed the caliper!
Be prepared to use plenty of rust penetrating spray!
A helpful tip: should you need to buy a new bleed nipple, they are the same as the front caliper bleed nipple from the 1990-2000 MR2.



Step 7:
As you can see, I removed the piston from mine. This is probably not necessary - and not something you want to do if you're working with the caliper on the car! However, I wanted to give my caliper a good flush through and clean out, along with the piston. Also, it's easier to work on the inner seal with the piston removed. The process should be the same with the piston in place or removed.



Removing the Piston:
The piston is removed just by turning it - it is on a thread inside. You can do this by using long-nose pliers to get a purchase on the front of the caliper and then turn them.
You can also create a tool to help you do this job (as Jimi has done). A T handle with a piece of 1" flat bar with welded to the end, drill 2 holes 24mm between the centres in the flat bar and use 2 x 6mm (9.5mm diameter heads) allen bolts in size.


Another alternative to the long-nose pliers and Jimi-tool is to get a piston winding tool - these are available from Halfords and most other motor factors for around 20 pounds. They look similar to a G-Clamp, with the ability to sit in the calipers well, and two studs on the circular face that sit in the piston quite well...

Okay, back on topic...

Step 8:
Winding the piston sounds easier than it is. If the piston is stuck, it will need a lot of pressure to move. With my caliper removed, I attached an air line (normally used for pumping tyres!) to the plug where the brake pipe normally attach's. I then placed a block of wood just in front of the piston to prevent it from getting damaged when it came out.
Be careful!!! This can be dangerous as the piston can come shooting out, so make sure it's not pointing at anyone/anything and that you have no fingers in the way!!!
The piston will take a while to come out but it will eventually pop out, and when it does, it won't be gentle!!! (Hence the piece of wood) An alternative method, particularly if the caliper is still on the car, is just to pump the foot brake with the brake line still attached - the pressure should be enough to push the piston out.


The Piston:
I looked at replacing mine but the ones I ordered from Brakes International were incorrect replacement parts and could not be fitted. I've tried to get them to work out what the correct ones are but they've given me no guarantees that they now stock the correct ones, which is a shame as at 20 or so pounds each, they're quite reasonable. Unfortunately I don't have the time to chase this up any more.
On the other hand Toyota sell the pistons (part number 47701-17010) for 45.99 each plus VAT. Twice the price, but at least you know that you're getting the right part.
Of course, this only matters if you have to change the piston completely, which may not be the case.

Myself, I ended up polishing mine really carefully then rinsing it out with brake fluid and that seemed to do the trick... Basically, if your piston is a bit mucky, clean it off as gently as possible. Avoid scratching it if at all possible. I used very fine wet and dry paper on the outside surface of mine as it had gotten into quite a mess...
If it's pitted or badly scratched, it needs to be replaced...

Right, now down to the actual refurb...

Step 9:
First step is to remove the old dust seal. This is more obvious in the earlier photos, but I pulled it off and some of it didn't come out, as shown in the next photo! (a part of it is marked out in green) You have to get the old spring out using a screwdriver and then try to remove all of the old seal. Again, I used a screwdriver for this as it needed scraping off, but you have to be careful not to damage the caliper underneath it.


During the removal:


Then, just give the area a clean-up. I got mine looking like this:



Step 10:
Remove the other easy-to-remove seals:



Step 11:
I then flushed mine through with brake fluid. Note: if you're going to clean the internals, use brake fluid to do so!



The Kits:
This is the caliper with the seal kit I got from Brakes International



The Brakes International Kit includes White Lithium Grease for the lubrication of the rubbers. This is the grease that you should use for the rubbers as it will not cause them to perish prematurely. An alternative is red lithium grease - this can withstand higher temperatures, although it seems to be more difficult to source elsewhere than the white lithium grease.
The Toyota kit includes the red grease, and everything in the Brakes International Kit except the slider pins, but does include new copper crush washers for the brake pipe banjo fitting.
Do not use any old grease you have as it'll likely make a mess of things, may cause the rubbers to perish prematurely and can make a refurb in the future more difficult! For example, even though copper grease is great to use on the back of the pads, or on bolts to prevent them rusting so soon - it's a big no-no for refurbing the brakes! Copper grease can make a mess of the rubber seals over a short time period!

Step 12:
On my caliper, the end-cap for the hole where the bolt goes into had worked itself off slightly, as you can see in the following photo. I fixed this just by using a G-clamp to gently push it back into place... (check it's still flat on!)


Step 13
There is an inner seal which has to be changed as shown:





This is very straightforward with just a screwdriver if you have removed the piston from the caliper. I do not know how this can be done with the piston in place...


Step 14:
With that seal changed, the piston can then be screwed back into place (the piston does not need to be lubricated - the brake fluid will provide enough lubrication). Screw it inwards as far as it will go (be careful not to cross-thread it! If it's been cleaned, then it should be fairly light).


Step 15:
Then you fix the new main dust shield into place:


(note: I forgot to get a photo of doing this and this is with the spring in place already!)

The dust shield just pops into place - just double check that it is fully in all around. A recommendation is that you lubricate this with the grease before fitting it as it'll make fitting the spring much easier (this is what you'll be doing next!). You'll need to check that this shield is the right way up - to do this you just have to look at it and note that the spring is going to go in the outer-most lip of the seal - this will only happen with the seal one way up. I hope this makes sense... essentially you just have to have a look at it and work out which way will give the greatest sealing pressure...


Step 16:
You then have to fit the spring - the metallic split-ring in the box. Now, the procedure is the same for in-situ as it is with the caliper removed. All I can say is... good luck if you're doing it in situ. Basically you have to just start by putting one end in under the outer-most lip of the rubber. You then work it around by pushing it under bit by bit. This is best done with a pair of long-nose pliers. You just have to keep working it around. Eventually the springs should overlap - in terms of the area covered. The entire spring should be hidden away. You have to make sure not to pinch the rubber dust shield as you don't want to damage it! There is no spare in the box so this could be a problem if you do...




So this is what it looked like when done:



Step 17:
I then wanted to ensure that the dust shield was properly fitted, so I threaded it back outwards again with the pliers - once I was satisfied I then wound it back in again:



Step 18:
Next up is the hole through which the sliding pin on the carrier goes. This photo shows the bits needed:



(Note: the metal slider is just there for illustration - it came right out again! Also note: I cleaned up all the surfaces to get rid of surface rust using sandpaper...)

Grease up the outside of the rubber plug and push it through the hole:



Step 19:
I then greased up the outside of the metal sheath/pin as it's going to be in contact with the rubber plug.



Push it through the rubber plug to fit it:



Et Voilà!



So far we have:



Step 20:
Now for the hole where the fixing bolt goes through. This one is fun. Basically this has another rubber seal on the end which is open. Chances are, like me (on more than one occasion!) you pulled off the rubber thinking that was all. Well, unfortunately not. There is a metal end to the seal, as you can see by looking at the new one:



It's not going to be easy to remove (unless you're lucky) - each time I've done it, it's been a bit of a struggle. It should just fit, and in this case I thought it would:


But alas, there's a bit still left here too:


(Note: this wasn't obvious at first as the metal ring was covered in crud and not visible as it looked as though it was part of the caliper. You have to scrub a bit to see it...)

I placed my caliper into a vice so that it was secured with this hole vertical. I then used a screwdriver and managed to lever it off around the edges. This time it came off cleanly:


When I did this the time prior to this, it was not so clean - as I said, we had to use the screwdriver as a chisel leading to lots of small bits coming out each time... This could be the most tedious part of the job. Perseverance and patience definitely required...

Anyway... I was left with this:


Step 21:
So, I wanted to push in the seal with the metal end to it, but it was a bit firm and not going in. I tried scrubbing out the hole a bit with screwdriver and sandpaper, but eventually lost my patience and used this route:


If you do use this method of a G-clamp to push it in, use something flat to ensure that the force onto the metal ring is even so that it is not bent out of shape! You can see that I used a metal plate here... Ideally you want the ring to be flat to ensure a good seal. I can imagine this is going to be a pain to remove again in the future though.

Step 22:
I decided to treat my caliper to a new bleed nipple - at £1 each it's not much!


There is a new dust cap for the nipple in the seal kits from Budweg (Brakes International)and Toyota - this is good as they do tend to go missing...


Just in case, this is where the bleed nipple goes:


And that's it - job done!
This is what's left over from the brake seal kit that I bought (note: I only got one tube of the lubricant, there was still some left... )



Since doing this job, I've had a good look at the BGB and it seems that the two items on the left are used for the handbrake lever seals. As I didn't disassemble this, I didn't use them. If I ever do this job as well, I will update this article.
However, I did give the handbrake lever and spring a good scrub down with a wire brush - actually I gave the whole caliper a good scrub down with a wire brush before starting as it was a real mess. If you do this, please wear a face mask and safety goggles - it's a very dusty job!

And, caliper now all done with the carrier fitted on - but only with the sliding pin, not with the bolt as well...:



And there you have it. The refurb process is now finished. If, like me, you removed the carrier as well (the carrier is the metal bracket that holds the brake pads), the fixing bolts for this should be torqued up to 59Nm (43 ft/lb).
If you have removed the caliper from the car, put it back onto the slider.

Winding the piston back in for the pads:
Before lowering the caliper onto the pads, Paul Woods has mentioned many times that to get the handbrake mechanism to work correctly, you need to wind it all the way in, then wind it 180 degrees back out. If the pads won't fit, then wind it back in 180 degrees, then in another 20 degrees, then back out 180 degrees - repeat until they fit.
A bit more on it here: CLICKY
You might get lucky and they'll work without doing this, but this way guarantees that the mechanism will work properly first time.


The bolt for the caliper (green in the diagram below) should be torqued up to 20Nm (14ft.lb). When putting the bolt in, it's a good idea to cover it (thread & head) in some grease (e.g. lithium grease) before hand to prevent it rusting into place 2 minutes after torquing it in...



If you want to fit replacement Stainless Steel braided hoses, now is probably the best time to do it!
Reattach the brake pipes, (torque for the brake tube union bolt is 15Nm; 11ft.lb) and of course the handbrake cable! As in the Haynes manual, installation is the reverse of removal. The handbrake fixing should look something like shown in the photo below (circled in green):



Now, the brakes probably won't work straight off, nor will the handbrake. You really should now bleed the brakes that you've worked on. Get all the air out of the system that has gone in!

A (quick) guide on how to bleed the brakes:

      * Get yourself a bleeding kit. These usually comprise of a pipe that fixes to the bleed nipple with a one-way valve on one end that should stop the fluid/air from going backwards into the system.

      * Ensure that your brake reservoir in the frunk has plenty of brake fluid in it.

      * Remember to start from the one furthest from the master brake cylinder (i.e. rear passenger side, then rear driver side)

      * Loosen the bleed nipple. I really recommend a decent spanner for this - they're worth the extra few pounds to prevent rounding off the head on the bleed nipple - ruining the bleed nipple could mean ruining the entire caliper if it won't come out! You'll probably need to use quite a bit of rust penetrant spray here. Of course, you could have also loosened it earlier as I instructed...

      * Plug the pipe onto the bleed nipple you're working on.

      * Undo the bleed nipple further so that air/fluid can come out.

      * If you have a one-man kit, pump the brake pedal so that the air/fluid comes out. If you don't have a one-man kit, get a friend to do it for you. Just an important point that needs to be reiterated... when you're bleeding the brakes, make sure the person who is pumping the pedal does not push it to the floor as it'll ruin the master cylinder.

      * Check the brake fluid reservoir in the frunk regularly. Last thing you want is for that to drain completely dry as this will allow air back into the system from the top - meaning it'll all need to be bled again. Also, be careful when filling the brake fluid reservoir that none is spilt - it's difficult to catch it all, and I've learnt from personal (painful) experience that any left behind completely ruins the paint in the frunk!

      * You can normally tell old fluid from new fluid as the older fluid is often a darker brown colour.

    * When you are sure there is no air coming out of the bleed nipple anymore, you can the tighten the bleed nipple off.


If you have someone else pumping the pedal, have them pump the pedal 6-10 further times, then hold it down while you release then tighten the bleed nipple. Remove the pipe and then double check there is no fluid dribble. Then fit the dust cap over the top for the bleed nipple.


When bleeding the brakes, I chose to completely replace my fluid as I had no idea what was in there. Toyota's Handbook recommends DOT4, but I (and quite a few others) use DOT5.

Next step?
Re-attach the wheel! If you have a torque wrench, torque tighten the wheel nuts to 76ft/lbs. You'll need a 21mm deep socket to do this.
Then, first time you start the car, pump the brake pedal a bit so that the brake booster pushes the piston out against the pads. Also, for the first couple of miles, drive gently. Make sure the brakes are fully operable and that you can still stop if you need to!!! Any problems, check that the pipe has been fully bled... If you're not happy with the brakes performance, or the pedal feels spongy, go back and re-bleed them just to make sure the system is definitely devoid of air... Good luck!


Oh - one final thing... enjoy your new-found braking capabilities!!!

Thanks must go to:
Tiamat for showing me how to do this the first time!
Kaiowas for letting me practise on his car!
LimeyMk1 for a variety of pointers.
Jimi for the Jimi piston tool...!
Sports Toyota Breakers for the replacement calipers!
And a number of other guys on the forums who at some point have answered one question or another that I've had, or raised a useful point, when I did this (names that come to mind: SystemG, MartG, Blokey, Cartledge_uk, Paul Woods, alfiembra, flippin'eck, jrleech, Karl_T, oukie
Toyota - obviously for a fantastic car, but also for the BGB (source of the illustrations above).

This is more an amalgamation of the knowledge gained from all the answers given to me than it is something new, and it wouldn't have been done without their help!
Many thanks guys!

May 2007

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