More progress in bring the car back to life.
I have been working on the front brakes today and have found the cause of the brake problem that caused the car to swerve to the right when the brakes were applied.
The LH wheel cylinder was seized on one side so only one shoe was partialy operating and the brake adjuster at the bottom was seized soild!
I have removed the cylinder and managed to free it off and on stripping it down there was rust in both bores but not too bad and a light hone should sort that out.
The brake fluid has obviously not been changed for several years and because the fluid is hydroscopic the water collected makes it way down to the lowest points in the system,the wheel and master cylinders and does its damage.
Changing brake fluid is a simple job and the cost is tiny compared with the damage it can do if not done every couple of years.
Some of the new generation fluids are silicone based so this problem would not happen but I am not sure about using them in in an old system
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Please don't post someone's email address to avoid it being harvested by spambots and it's against GDPR regulations.
Always look at "ACTIVE TOPICS" to see all posts in date & time order as they are sometimes moved; or look at "Your Posts".
Please add Reg. nrs. when posting a photo or anything about a car as this will help searches. Don't add punctuation next to nr. as this negates search.
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DB18 SS Brakes
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tpickering
- Posts: 119
- Joined: Wed Jan 20, 2021 3:32 pm
- Location: Stratham Western Australia
Re: DB18 SS Brakes
On page 85 of the owners handbook is stated
Warning -- On no account should fluid other than Wakefield Girling Brake Fluid (crimson) be used.
If you look the pictures below you'll see that the spec was SAE 70R1 and SAE 70R3 (right click on each image and open in new tab so as to be able to read the writing).
Brake fluids are now sold with the American DOT standard as the rating on the bottle, and it's difficult to find out if SAE 70R1 was equivalent to DOT 2 (primary constituent castor oil/alcohol) or DOT 3 (primary constituent glycol ether). However, because the second picture has a warning, and going on my (possibly incorrect) assumption that castor oil/alcohol is not corrosive, the closest to SAE 70R1 would be DOT 3 since glycol ether is corrosive.
If you go into Halfords you'll see that they only sell DOT 4, DOT 5, and DOT 5.1
As with DOT 3, DOT 4 and DOT 5.1 also use glycol ether as the primary constituent, but DOT 4 and DOT 5.1 also have borate ester in the mixture (mostly to raise the boiling point). Note that DOT 5 is very different and uses silicone as the primary constituent.
The main difference between DOT 3, DOT 4, and DOT 5.1 is the boiling point and since the wheel cylinders on these cars are external and away from the brake shoes, the wheel cylinders are unlikely to ever get hot, so I go for whatever is cheapest and easiest to obtain - DOT 4.
If you want to use DOT 5 you'll have to renew the piping and completely clean and dry out the wheel cylinders and master cylinder - and enquire from e.g. Beales as to whether their seal kits are compatible with DOT 5 (I know from usage that the seals are compatible with DOT 4). Alternatively, maybe convert to the Citroen LHM fluid (again you'd need to renew the piping and check the compatibility with the seals).
Warning -- On no account should fluid other than Wakefield Girling Brake Fluid (crimson) be used.
If you look the pictures below you'll see that the spec was SAE 70R1 and SAE 70R3 (right click on each image and open in new tab so as to be able to read the writing).
If you go into Halfords you'll see that they only sell DOT 4, DOT 5, and DOT 5.1
As with DOT 3, DOT 4 and DOT 5.1 also use glycol ether as the primary constituent, but DOT 4 and DOT 5.1 also have borate ester in the mixture (mostly to raise the boiling point). Note that DOT 5 is very different and uses silicone as the primary constituent.
The main difference between DOT 3, DOT 4, and DOT 5.1 is the boiling point and since the wheel cylinders on these cars are external and away from the brake shoes, the wheel cylinders are unlikely to ever get hot, so I go for whatever is cheapest and easiest to obtain - DOT 4.
If you want to use DOT 5 you'll have to renew the piping and completely clean and dry out the wheel cylinders and master cylinder - and enquire from e.g. Beales as to whether their seal kits are compatible with DOT 5 (I know from usage that the seals are compatible with DOT 4). Alternatively, maybe convert to the Citroen LHM fluid (again you'd need to renew the piping and check the compatibility with the seals).
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tpickering
- Posts: 119
- Joined: Wed Jan 20, 2021 3:32 pm
- Location: Stratham Western Australia
Re: DB18 SS Brakes
Thanks Brian
i did some reading a settled on DOT 3 myself.
i did some reading a settled on DOT 3 myself.
Re: DB18 SS Brakes
I don't think that the borate ester in DOT 4 is a problem and, relative to DOT 3, DOT 4 is easier (and cheaper) to obtain. I think that DOT 4 can be added straight into DOT 3 anyway, so there's no requirement to completely flush out DOT 3 when adding or totally upgrading to DOT 4.
From what I've read, most modern cars use DOT 4 because it is the least compressible brake fluid of the lot and is therefore best for ABS systems. The military use DOT 5 because there's no requirement for ABS in tanks etc and DOT 5 is more consistent across a wider range of temperatures and has a longer life in the system.
If I were to convert away from DOT 4 (or 3) in a non-ABS car I'd go for LHM.
From what I've read, most modern cars use DOT 4 because it is the least compressible brake fluid of the lot and is therefore best for ABS systems. The military use DOT 5 because there's no requirement for ABS in tanks etc and DOT 5 is more consistent across a wider range of temperatures and has a longer life in the system.
If I were to convert away from DOT 4 (or 3) in a non-ABS car I'd go for LHM.