I am rebuilding my S3 brakes. Water that has been absorbed into the normal brake fluid during the car’s tenancy in a damp garage during the cold winter months in the past years has pitted the hard chrome plating on the caliper pistons. Presumably more use throughout the year would have evaporated off the water as the fluid temperature rose during braking.
Two things spring to mind: a long lasting non-hygroscopic brake fluid such as silicone, and stainless caliper pistons. Is this type of fluid safe to use in an Elan and where can I buy stainless pistons?
Although many scorn the use of silicone fluid, i’ve used it for nigh on twenty years. no probs, no rubber deteriation, no problem with pedal travel. Got stainless (rear) caliper pistons from Chris Neil at the same time - no probs. Front calipers from Classicar(?) again no probs.
Only used for road and Goodwood and Castle Combe days. I expect I’d almost certainly have to have to change it if I was doing trackdays, but I’ll still use it til I definately need to change. Just read the post about Castrol SRF - looks like good stuff.
Local car accessory shop told me Dot 5 and 5.1 is silicone… it’s not. Check the label.
I use Namrick fluid.
Try
John Farrell Auto Parts
57D Alder St.
West Babylon, New York 11704
USA
Phone: (631) 454-7977 (800) 454 7977
Fax: (631) 694-7217
Email: [email protected]
web page with specific parts
fortunecity.com/silverstone/ … 6/id23.htm
rear Elan
64325873 19-1209 1.334" A Lotus Elan 1962-76, Maserati, Peugeot $22.00
Front Elan
64327369 19-1013 1.892" C DeLoreon, XJS 1980-91, Lotus Esprit 1980-84,
Morgan +8, 1980-86, Triumph Spitfire $26.00
Prices are almost free at a $2.00 for a 1 GBP note, well not quite but a good deal none the less. I have bought several sets for various Lotus cars and have not had any problems.
Gary
I was warned off using silicone brake fluid.
The theory offered to me at the time made some sort of sense.
“Normal fluid is hygroscopic, (which means it absorbs moistuure) & over a period of time will lower its boiling point etc. therefore it should be replaced at regular intervals”.
“Silicone fluid is (apparently) not hygroscopic so any moisture in the systen will not be absorbed. This non absorbed moisture when hot could form gas bubbles that would cause a soft pedal”
“The racers don’t use silicon fluid for this reason”
Please note the quotation marks!
Rohan with his racing & oils knowledge is the man & will probaly be able to put this discussion to bed
I have paid a lot of attention to my Elan’s brakes, without them the car would be lousy, the better the brakes, the better the fun
Cheers
John
What car do you run and what brakes do you use
1970 Elan S4SE Drophead. 185bhp, 2 litre Zetec, 4speed g/box, +2 front brakes servo deleted, ss braided lines. 4 pot (Willwood maybe) calipers only a pipe dream away. The later you can leave your braking is so much added fun value
John
Hi
I can only concur with the view regarding the use of this stuff. I’ve used silicon fluid for over 25 years and I can only say I’ve never experienced soft pedal problems etc.
Correct me if I’m wrong on this point but I would have thought that for a braking system to attract water hygroscopically (if the word exists) the fluid within it must by its physical characteristics be “water hungry”. Liken this to the reason why bread left in the air goes hard and biscuits go soft (not a good analogy I know). The water content in bread is (usually) greater that that of the surrounding air- biscuits the opposite. The two moisture levels will tend to equalise over time. As far as I know silicon fluid doesn’t have the property to attract water so presumably any water entering the system could only get there via the master cylinder filler cap and not via the flexible pipes.
Regards
John
Racers dont use silicone fluid for 2 reasons I believe
-
The boiling point of silicone is lower than a fresh good quality racing fluid like Castrol SRF. Silcone is still superior to an old ocnventional fluid with lots of water in it
-
The fluid itself is more compressible and produces a softer pedal feel. Racers like a non boosted system and hard pedal for maximum feel
I used silicone fluid in my elan when I first rebuilt it and was using it mainly as a road car. As it evolved into a more serious racer I changed to SRF and similar non silicone brake fluid basically for the reasons above.
I also had problems with seal life in the clutch slave cylinder which I put down to the effect of silicone on the seal lubrication leading to more rapid wear.
I left my road plus 2 on silicone for a while longer but eventually changed it back to conventional brake fluid due to seal life concenrs and also because it was just easier to minimise the types of brake fluid I had around the garage.
The attraction of silicone (DOT 5) fluid is that corrosion in the brake system is slower as less water gets in. For a classic car with limited use it means you dont have to change the fuid every couple of years to stop corrosion and ensure adequate brake performance when you take it out for a track day once a year. The slightly softer pedal feel and maybe accelerated seal wear is not important in these circmstance.
For a car in regular use and regular servicing or a racer I would stick with conventional fluids ( DOT 4 or 5.1) which is where I ended up
cheers
Rohan
I thought Castrol SRF was silicon? Perhaps a better silicon fluid?
Gordon
I changed two of my cars to silicone. In order to do this the braking system has to be completely clear of old brake fluid. Lines flushed and blown out and all calipers completely clear of regular brake fluid. If you fail to do this a short time after installation the brake fluid will start to ‘foam’ and you will bleed, run a few days, bleed, etc. After about 2 months the foaming will stop and you will have no more prob.
SRF is synthetic racing brake fluid manufactured by Castrol. It is a DOT 4 type material.
I recently changed my S4SE (+2 front brakes, no servo & braided lines) over to SRF and I no longer get a soft pedal when pressing on (only on the track of course). With this set up I can certainly brake very late in total confidence. With the +2 brakes and no servo the pedal is hard with no travel giving good feel with out being too sensitive which makes heel ‘n’ toe easier.
The SRF is a bit expensive but then quality always is.
At the rist of being pedantic:
“Castrol SRF evolved as a direct result of Castrol’s ongoing Research and Development program for brake fluids which identified this silicon ester technology as providing considerable performance benefits when compared with conventional glycol ether borate ester fluids.”
It’s obviously in a different catogory to the (other) ‘silcon brake fluids’, as it is classed as Dot 4. Just wanted to make the point that using the word silicon doesn’t differentiate between the 2 types - using the DOT category does. (Which I should have said in the first place!!).
I concur with Gary’s recommendations to purchase stainless pistons from John Farrell. Beautiful pieces for a great price (mid $20 each a couple of years ago - exactly $200 for all 8 pistons).
Gary got the part numbers correct: 7369 and 5873 show up on my invoice from Farrell. These numbers fit perfectly in the caliper bores, with the stock seals, and with the stock dust covers.
I remember reading a few years back (in Road & Track, I think) that when the Loughead (Lockheed) brothers invented hydraulic brakes they originally used water for brake fluid, thus the term “hydraulic” brakes. Forget about fluid boiling - think about it freezing! Yikes.
Rich Boyd