Caliper rebuild - Questions

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Feb 27, 2005
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Santa Cruz Mtns
In the middle of a front caliper rebuild (was hoping to have it done in one day, yesterday :mad:) but ran into a few issues. Was hoping to get a bit of consultation.

Been using Slomo's write-up as a guide :)cheers: Slomo): https://forum.ih8mud.com/80-series-tech/175627-brake-caliper-rebuild.html

Pulled the pass. and driver side pads. Stomped on the pedal a few times to break loose a stuck piston and get the rest partially out. Removed the calipers and began extracting each piston. For both calipers: 1 came out easy, and 5 required the two screw driver method. At this point, I have one piston in each caliper that are both "stuck" about half way out. I think one will come out with more two screw driver method (can move it in the bore a little) but the other one is being a b!%$#. As a note: all my pistons had caked on grime and rust flakes under the boots.

Also, I am flushing the system due to nasty fluid. Ref: IH8MUD.com - View Single Post - Brake Flush

Questions:
(1) To this point, I have done the 2 screw driver method a few times and the lip of a few pistons are less than perfect with possible scratches in the neck down area where the seal sits (not the actual piston surface). Will I be okay here? Can get picks tonight if it helps.

I was also thinking to add a bit more grease in this area to help in "water proofing" a bit. Good idea?

(2) The 2 pistons that are half way out: Can I assume they will actually come out with the correct 2 screw driver method because they are already half way out? I have been trying all the possible angle combos to inch them out but the screwdriver would slip and I have a few sore fingers, as a result.

Any tips or tricks I am missing? I was thinking - lube the side of the piston that is exposed, compress it back into the bore, and try to get some grease down in there. Good idea?

(3) The write-up references non-moly grease. I looked around on the web but could not find any good info on non-moly (or variants of the spelling). I see that Slomo used Redline Synthetic. I have Silkolene Pro RG2 Grease (Red): Silkolene USA - Products
Specs:
  • A high temperature, waterproof synthetic racing grease designed to meet the demanding requirements of competition and general all around usage
  • High-stress, high-cling formula is ideal for protecting wheel, steering head bearings, suspension linkage and other similar components
  • Lithium complex base formula is GC-LB approved

Its a synthetic but I am not sure if it qualifies as non-moly. Can I use this for reassemble?


I think that is it for now... sure appreciate all the help!

:cheers: :beer:
 
Pulled the pass. and driver side pads. Stomped on the pedal a few times to break loose a stuck piston and get the rest partially out. Removed the calipers and began extracting each piston. For both calipers: 1 came out easy, and 5 required the two screw driver method. At this point, I have one piston in each caliper that are both "stuck" about half way out. I think one will come out with more two screw driver method (can move it in the bore a little) but the other one is being a b!%$#. As a note: all my pistons had caked on grime and rust flakes under the boots.

I was in somewhat a similar situation to you. IMHO once they get to that point, you may want to consider remans as opposed to rebuilding the caliper. You can rebuild them, but if they are that bad then you will always be wondering in the back of your mind if they will fail.

But brakes are one of the systems on the vehicle that I do not mess around with. I can't think of many situations where I could get my family killed if the HG blows, I can think of tons if the brakes fail.

Remans are actually very reasonably priced as well, though not nearly as cheap as a rebuild.

If you want to do a rebuild, you *CAN* disassemble the calipers. You aren't supposed to (Toyota says not to), and the internals (such as the o-ring inside) are unobtanium. I don't know if that will let you get any further than you are now, as I'm not entirely sure if that'd let you access the back of the piston or not.


Questions:
(1) To this point, I have done the 2 screw driver method a few times and the lip of a few pistons are less than perfect with possible scratches in the neck down area where the seal sits (not the actual piston surface). Will I be okay here? Can get picks tonight if it helps.

Minor (surface) scratches shouldn't be a big deal. If you're worried about them you can buff them out.

Deeper scratches will cause the piston to leak. I had clay that got under the boot and scratched the pistons, which caused them to leak. It didn't take much to do it either.

I was also thinking to add a bit more grease in this area to help in "water proofing" a bit. Good idea?

I don't think you need to worry about water proofing it too much.


(2) The 2 pistons that are half way out: Can I assume they will actually come out with the correct 2 screw driver method because they are already half way out? I have been trying all the possible angle combos to inch them out but the screwdriver would slip and I have a few sore fingers, as a result.

Any tips or tricks I am missing? I was thinking - lube the side of the piston that is exposed, compress it back into the bore, and try to get some grease down in there. Good idea?

If I were rebuilding mine, this is the method I'd use.

Moss Motors, Ltd - Removing Caliper Pistons

A Plug for Calipers
When rebuilding disc brake calipers, your shop manual or other service instructions probably recommended removal of the pistons by using pressure from the hydraulic system. However this method is not only messy, but inhibits the work by allowing removal of only one piston at a time. It also forces you to work on the caliper under the confines of the wing while it is tethered to the chassis by the brake hose.
However there is an alternative mechanical method which permits removal of both pistons at once while allowing you to do the work off the car. Remove the caliper assembly from the car, disconnecting the hydraulic hose at the caliper. Determine the inside diameter of the caliper piston, then visit the hardware store and find a plumber's "test plug", or try the auto store for the rubber plug used to replace the steel expansion plug in a cylinder block core opening. Both are rubber sleeves with concave washers at each end and a center bolt used to compress and swell the rubber sleeve. Choose one of a diameter as close as possible to the piston bore.

Now cut a piece of 1/4" X 1" steel strap about 6" long and drill a hole in the center that will fit the bolt in the expansion plug. Install the strap on the center bolt with the nut finger tight and cut off the bolt flush with the nut.

Insert the plug in the piston bore, install the strap and tighten the nut securely to cause the plug to grip the inside of the bore. If the plug should prove too small to expand enough to grip the piston, securely wrap a few turns of "rubber" tape around it until it is large enough to grip as needed. Rubber tape is far better than plastic or electrical tape because it will expand with the plug-having good friction characteristics.

Once the plug is tight in the bore grasp the caliper and tool assembly with both hands, placing the thumbs on the back of the opposite cylinder and the fingers around the strap. Squeezing the hands closed will extract the piston from the bore. Then repeat for the opposite side. Either this tool or a C clamp can be used to install the pistons following the rework.

17.jpg

(3) The write-up references non-moly grease. I looked around on the web but could not find any good info on non-moly (or variants of the spelling). I see that Slomo used Redline Synthetic. I have Silkolene Pro RG2 Grease (Red): Silkolene USA - Products
Specs:
  • A high temperature, waterproof synthetic racing grease designed to meet the demanding requirements of competition and general all around usage
  • High-stress, high-cling formula is ideal for protecting wheel, steering head bearings, suspension linkage and other similar components
  • Lithium complex base formula is GC-LB approved

Its a synthetic but I am not sure if it qualifies as non-moly. Can I use this for reassemble?

Moly grease nearly always says something like "Moly fortified."

If it doesn't say that, then you should be fine.
 
Can you use a rag to protect the piston and vice grips? Once the're on you can twist, pull and rock the piston pretty well with a lot more force. If it's tight, you might consider going and buying a smaller/thinner pair of vice grips that will let you do it. They make them in an astonishing array of angles and sizes these days.

DougM
 
I was in somewhat a similar situation to you. IMHO once they get to that point, you may want to consider remans as opposed to rebuilding the caliper. You can rebuild them, but if they are that bad then you will always be wondering in the back of your mind if they will fail.

But brakes are one of the systems on the vehicle that I do not mess around with. I can't think of many situations where I could get my family killed if the HG blows, I can think of tons if the brakes fail.

Remans are actually very reasonably priced as well, though not nearly as cheap as a rebuild.

If you want to do a rebuild, you *CAN* disassemble the calipers. You aren't supposed to (Toyota says not to), and the internals (such as the o-ring inside) are unobtanium. I don't know if that will let you get any further than you are now, as I'm not entirely sure if that'd let you access the back of the piston or not.

Thanks for the info on the reply. I appreciate the help.

I hear what you are saying about possible buying remans... started to think that way but then did an experiament last night. My pass. caliper had 3 really stuck pistons but one came out easy. Managed to get another one out (2 are now remoaved) but was having trouble with the other 2. Decided to polish up the ones I got out, cleanup the bores, grease'm, and reinstall them. Mounted the caliper, bled that side, and used the hydrolic preasure to push out the 2 stuck ones. Unmounted (got better at not making a HUGE mess) the caliper and was able to remove another "stuck" one... the other two that I polished up were easily removed (and held a good seal in the bore even with the old rubber ring in the bore). This gave me a bit more confidence to move forward without the remans. That leads me to this post... the 4th piston was pushed out as much as it would go and is now sticking half way out.

Not planning to "split" caliper... rebuild to me is only doing what is described in the FAQ.

Also... I hear you on the safety side of things. I plan to get this work done and have my local trusted shop do a once over to be sure things are solid.

Minor (surface) scratches shouldn't be a big deal. If you're worried about them you can buff them out.

Deeper scratches will cause the piston to leak. I had clay that got under the boot and scratched the pistons, which caused them to leak. It didn't take much to do it either.

I don't think you need to worry about water proofing it too much.
Thanks for this info as well. I will inspect the piston surfaces closely.

If I were rebuilding mine, this is the method I'd use.

Moss Motors, Ltd - Removing Caliper Pistons

Now that is a dam good idea! I may have to be sure I get going on this before the hardware store closes.

Moly grease nearly always says something like "Moly fortified."

If it doesn't say that, then you should be fine.
Sweet... I will take a look at the spec sheet online. I am almost certain that language is not on the sheet anywhere.
 
Can you use a rag to protect the piston and vice grips? Once the're on you can twist, pull and rock the piston pretty well with a lot more force. If it's tight, you might consider going and buying a smaller/thinner pair of vice grips that will let you do it. They make them in an astonishing array of angles and sizes these days.

DougM

Thanks for the reply Doug. I am planning to test out your suggestion first.

It almost feels like the piston is just slightly "off center" in one direction... just cant figure out which one. And with all the grime, flakes, and crap in there it doesnt take much for it to get "off center" in the bore. Just wasnt sure if I was "missing" something and should not contiue trying.

Or... maybe I just needed some emotional support :D

:cheers:
 
Would you bet your life on them. Id get some rebuilt or new ones. 2 cents Mike
 
Was just thinking about this some more.... if no progress is made I am going to apply a combo of the "plug method" (shown above), compressed air, vise script idea and/or two screw drivers methods

I envision it something like this...
  • clean and setup the 3 remaining bores as if I were going to reinstall it
  • On side with two good pistons: clamp both pistons down so they cannot move.
  • On side with problematic piston: use either the plug or another clamp on the good piston
  • Inject the compressed air and, at the same time, use the vise script and/or two screw driver method.

This should give some push from the rear while wiggling the piston loose… being careful that the piston doesn’t all of sudden become a projectile. Then, once its out I will only have one more bore and piston to cleanup :D
 
What is the grease for? If you are talking about for the brake calipers/pistons/seals, I used "brake lube/grease", which I believe is a silicone lube/grease. Should be available at any parts store, for cheap.
 
What is the grease for? If you are talking about for the brake calipers/pistons/seals, I used "brake lube/grease", which I believe is a silicone lube/grease. Should be available at any parts store, for cheap.

x2

I was at Pep Boys trying to track this special grease down and the underpaid guy behind the parts counter had no idea what I was talking about. Walked across the street to Orchard Supply and in their auto section (20 times smaller than Pep Boys) they had a nice assortment of special glues/chemicals/etc from permatex and one of them was "Disk Brake Grease" for $2.99. Bingo. On the package it even said for disk brake pistons :)

BTW - If you bought the Toyota caliper rebuild kit there's a packet of this grease included.
 
Oooh... I have some of that disk brake grease... and plenty of it :) Was using us on the back of the 100 series pads to quiet them down. Thanks guys! :cheers:

The packet of pink stuff is in the rebuild kit. I made use of it last night and am running a bit short.
 
Just remember that a NEW pair of vice grips will have sharp teeth that can gouge the piston. Carefully choose the rag or other material you're going to use so it's a substantial fiber that won't be cut through easily. Perhaps some thin tin or something over the teeth.

Good luck with it. BTW, it's too late for you but there's a great method in the 80's factory manual detailing how to cut a chunk of wood to the right size so you can use the brake pedal to release all the pistons before removing them to rebuild.

DougM
 
Was just thinking about this some more.... if no progress is made I am going to apply a combo of the "plug method" (shown above), compressed air, vise script idea and/or two screw drivers methods

I envision it something like this...
  • clean and setup the 3 remaining bores as if I were going to reinstall it
  • On side with two good pistons: clamp both pistons down so they cannot move.
  • On side with problematic piston: use either the plug or another clamp on the good piston
  • Inject the compressed air and, at the same time, use the vise script and/or two screw driver method.

This should give some push from the rear while wiggling the piston loose… being careful that the piston doesn’t all of sudden become a projectile. Then, once its out I will only have one more bore and piston to cleanup :D

This worked pretty well. It provided the preassure behind the piston while I was able to jiggle it side to side.

All pistons are out. I am in the process of cleaning. The last piston I started to clean looks questionable. Opinons?
P4260377.jpg
 
You can get new pistons from Cdan (or your local dealer if you have the part number).

Toyodiy.com lists the following info:

47731 PISTON, FRONT DISC BRAKE
47731‑60010 FZJ80, FJ80 8 $27.16

47731B PISTON, REAR DISC BRAKE
47731‑60020 FZJ80 2 $28.67

For those prices I would not reuse the piston.
 
Thanks guys. I am going to order 2 new ones. There was another one that was not as bad but will replace it since I am in there.

I appreciate all the help! :cheers:!
 
Rebuilt the rear calipers last night (front & rears now rebuilt, system flushed and bleed in proper order according to FAQ). Pad wear was very even on both side, probably had 2/3rds of pad left on each side, and calipers came apart pretty easy. The squel that I was hearing from the rear were the caliper parts grinding into the pads... and when I say *into*... I mean boring (not sure if it matters but, they were not OEM pads).

This leads me to a few more questions...
(1) In Slomo's thread... there appeared to be a "metal clip" that clipped over the back of the pad in the pic (non piston side). My rears did not have this "metal jacket" on the old pads... am I missing one on each side for each caliper? Also, do the fronts use this “metal clip”?

(2) My braking issue (or believed to be) is still not solved :(
Happens when:
  • braking between 50 down to 35mph = violent shake in steering wheel (good pedal, braking power, no pulsing in pedal, no pedal fade)
  • braking between 35 down to 25mph = slight shake steering wheel and pulsing is noticeable (good pedal, braking power, no pulsing in pedal, no pedal fade)
  • braking between 25 down to 0mph = the pulsing in more pronounced
Thought it might be the ABS acting up. Tested it in the following way (assuming it is working properly because I have NEVER had it go on… even under heaving breaking): drive and be sure the issue is happening… hit the CDL and ABS light goes on… then do some heaving braking and the issue still occurs.

I have noticed that this issue seems to happen and become more pronounced after driving for bit. Also, I have developed a slight shake in the steering wheel at mid to higher speeds. Read this thread: https://forum.ih8mud.com/80-series-tech/196694-pulsing-brake-problem.html ... where Romer mentioned that first 3 things you check in pulsing brakes are Tires (Balance), Alignment, and then actual brakes).


Could it be my MC or possible tires out of balance???

All in all… the brakes feel dam good :D Just need to work out this issue!
 
Did you replace the rotors during the brake job? That would be my first guess, especially if some of the pistons were a bit seized and/or dragging. Second guess would be loose wheel bearings or some part of the suspension/steering linkage or tire balance. Though you also mentioned a slight shake in the steering wheel. If that's independent of braking, it may be worth tracking down the cause of that first, and seeing if that solves the braking issue? Have you gone through the front axle evaluation post? Might be worth doing since its just time and not money. https://forum.ih8mud.com/80-series-tech/137411-front-axle-evaulation-faq.html

My rotors are warped right now (thanks to PO and crappy off brand) and I find it much more noticeable in the steering wheel than in the brake pedal.

fwiw
 
Last edited:
Warped rotors or loose wheel bearings.
 
Thanks for the reply guys.


Will check the wheel bearings tonight.

Shoot... will have to drop it off to get the rotors looked at (fronts and rears I assume) and see if they can look at the tire balance at the same time.

For my own knowledge... I thought you would feel a warped rotor in the pedal?
 

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