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Wandering Willy *******
Joined: 18 Jul 2007 Posts: 1016 Location: Norfolk
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Posted: Sat Mar 21, 2009 12:50 Post subject: Sticking Brake Caliper Pistons |
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This is a quick fix for a sticking brake piston. The full treatment is to take off the caliper assembly, remove the pistons, clean and grease them, reassemble and refit onto the car. However, the approach described here could be carried out at the side of the road or used as preventative maintenance.
From owning a couple of Toyotas (a Previa and the current Amazon 100 series) I have found their brake calipers more likely to have a stuck piston than other cars I have owned. The description and photos are from my 100 series but the process could be applied to other models. I have used it to good effect on several Saabs and VW cars as well.
Obviously, all the usual warnings about jacking a car up and working underneath, and being careful with brakes apply here.
This is the offending brake. The lower inner piston had seized and been freed with WD40. However, this was only a temporary fix.
NB The Amazon has 4 pistons in a fixed caliper. The same technique can more easily be applied to the rear caliper or on other cars where the caliper is mounted in a slide. Sliding calipers give much better access to the piston and seal area.
Removing one of the brake pads gives access to the pistons
It is then necessary to pump the brake pedal to extend the piston out of the housing a little. Use an old worn (thin) brake pad to prevent the pistons coming out completely.
The extended piston can then be cleaned with some cotton buds to remove old grease, WD40 and rust
Several cotton buds will be needed to do this effectively.
A pipe wrench can be used to grip the edge of the piston to rotate it so that the complete circumference of the piston can be cleaned.
Be very careful not to trap the outer weather seal under the jaws of the wrench when rotating the piston. A wrench with narrow faced jaws is best for this job. The wrench doesn't have to be high quality or expensive as little force is used.
When the piston has been cleaned, the syringe can be used to inject new red brake grease under the outer weather seal. The piston can be rotated to cover the circumference of the piston with grease.
Please note that the small rubber teat shown fitted to the end of the syringe was not useful. The grease was injected using the syringe on its own without any fitting on it. The 5ml of grease in the syringe was sufficient to treat the 2 pistons on each side of the caliper assembly. While a larger syringe would save the task of refilling, its larger diameter would restrict its access to the piston being treated.
The treated piston is then pushed back into the caliper. The objective is to slide the piston fully into the caliper so that grease is spread around the circumference of the seal filling the space between the piston and caliper. This will reduce the risk of water entering and corroding the piston surface.
If you are concerned about possible damage to the ABS system, the bleed nipple can be opened to allow fluid to escape rather than being forced back into the master cylinder. However, if the pistons are properly lubricated, compressing the lower piston should result in the upper piston moving out to balance the volume of fluid in the caliper.
The process can be repeated on the other 3 pistons with the result that the caliper operates properly without the brake binding on the disk when the brake pedal is released. As mentioned above, the pistons also have a degree of protection against water entering when the car is driven through deep water.
Castrol Red Brake grease can be purchased off the internet. This tub was bought last year for about £5. Other brands may also be available but ordinary (lithium type) grease should NOT be used to this task.
Willy |
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Posted: Sat Mar 21, 2009 12:50 Post subject: Google Ads keep this community free to join! |
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Nuclear Chicken Lifetime member
Joined: 26 Feb 2009 Posts: 561 Location: Nordy Land
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Posted: Tue Mar 24, 2009 12:23 Post subject: |
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Very useful post. Following on from my own LC5 brake pipe repair, my front calipers are on the next on the 'to be checked' list. The disks are nice and shiny all round so I suspect all is OK but easy to check and clean it all up now whilst it's working. _________________ '04 KDJ120R LC5. Died 17th Dec 2010. RIP. |
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leon *****
Joined: 20 Apr 2009 Posts: 593 Location: Newcastle UK
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Posted: Sat May 16, 2009 2:14 Post subject: |
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Quote: |
Castrol Red Brake grease can be purchased off the internet. This tub was bought last year for about £5. Other brands may also be available but ordinary (lithium type) grease should NOT be used to this task. |
did you get it direct from castrol ?
I'v been looking for brake grease for 20 years ......every one said it didnt exist
just looking at those photo's i should do a "how to " on replacing rubber bush's
is the red on the hub face a grease ? I do note that some times i got to kick my wheels and hard to get them off as they seem to glue to the hub face.I'v tryed WD40 and white grease ... _________________ Should I have these bit's left over ?
1998 V8 LC Amazon VX work in progress
2008 pug boy
2009 pug boy
2010 pug girl
^ dogs |
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Wandering Willy *******
Joined: 18 Jul 2007 Posts: 1016 Location: Norfolk
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Posted: Sat May 16, 2009 11:28 Post subject: |
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Hi Leon
The red on the hub face comes from me painting the inside of the alloy wheels. I used smooth Hammerite over their alloy primer (which is pink when in the tin but dark red when dry). Where the wheel is bolted to the hub, the paint is squeezed and some has stuck on the hub showing the primer.
If you can get a heavy waterproof grease it is more lkely to stay on the hub face to stop corrosion and the wheel sticking on or being difficult to replace. This is the sort of stuff I mean:
http://www.quayleisure.com/rock-oil-mpg-waterproof-grease-500g-pot-p-1096.html?currency=GBP
Places that supply farmers or truckers might have what I mean so if you have a stockist locally, try there. Alternatively, try some Waxoyl on the hub face. It should last better than the lithium bearing grease which is soft. The Waxoyl dries and sets to a fairly hard sticky layer.
I would avoid putting a lot of grease on because tyres - particularly the side walls - don't lke being coated in oil or grease. It encourages the rubber to perish and crack. The tread is usually made of a mixture of natural and synthetic rubber but the side walls on radial tyres are mostly natural rubber which is more prone to deteriorating.
The red rubber grease came from the MG owner's club (based near Cambridge) who were having a clear out at the time I bought it. However, I don't think they sell general use stuff like that any more - only MG parts. You can still get the grease though from Castrol and some of the classic car specialists.
This URL lists the grease and the same web site has a contact number for Castrol. I am fairly sure if you phone them they will be able to supply you direct or suggest a retailer where you can get it.
http://www.castrol.com/castrol/sectiongenericarticle.do?categoryId=9014109&contentId=7027101
Alternatively, Frosts have another brand of the red brake grease:
http://www.frost.co.uk/item_Detail.asp?productID=9198&frostProductName=Red+Rubber+Grease+%28500g%29&catID=14&subCatID=&FrostCat=Brakes&FrostSubcat=
(sorry about the long link)
Willy |
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leon *****
Joined: 20 Apr 2009 Posts: 593 Location: Newcastle UK
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Posted: Sat May 16, 2009 18:05 Post subject: |
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sweet only £8 as well _________________ Should I have these bit's left over ?
1998 V8 LC Amazon VX work in progress
2008 pug boy
2009 pug boy
2010 pug girl
^ dogs |
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mudmax Newbie
Joined: 06 Oct 2008 Posts: 5 Location: Bristol
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Posted: Fri Jun 19, 2009 0:09 Post subject: |
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[url=http://www.frost.co.uk/item_Detail.asp?productID=9198&frostProductName=Red+Rubber+Grease+(500g)&catID=14&subCatID=&FrostCat=Brakes&FrostSubcat=]smaller link[/url] edit: oops! perhaps not! |
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johnmcc **
Joined: 15 Jul 2008 Posts: 92 Location: Norfolk
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Posted: Wed Jul 07, 2010 16:03 Post subject: |
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Just found this thread - excellent, thanks. |
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Wandering Willy *******
Joined: 18 Jul 2007 Posts: 1016 Location: Norfolk
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Posted: Sat Jul 31, 2010 11:59 Post subject: |
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Just an update.
I spent yesterday morning cleaning and checking the brakes on my amazon. The rear pistons were just on the point of sticking.
I think the reason is that the car doesn't do a lot of miles (about 4000pa) and I try to avoid heavy braking. As a result the pads show very little signs of wear (after about 12,000 miles - EBC Greenstuf). The next link in the logic is that the pistons sit in the same place relative to the seals as well.
Anyway, I cleaned out the old grease, put in new stuff and worked the pistons up and down a couple of times. All seems to be well.
I just mention this to encourage you to check your brakes now. It is much nicer to sit in the sun and do this job that it will be next January!
Willy _________________ 100 Series 2002 GX diesel automatic |
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