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Integrator
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2,740 Posts
Master Cylinder, Esprit

Thanks for your reply, I will give that a shot and see if there is any change. I am skeptical that there is still air in there but I suppose anything is possible. Ill let you know. Thanks for the FB shout out. Cars and Coffee was a blast!
'When you're there" you may want to flip the SC - so the bleeder is at the highest point. It makes expelling air easier.

also see #25 here https://www.lotustalk.com/forums/f164/s4s-s4-se-updates-improvements-439737/index2.html
and
https://www.thelotusforums.com/forums/topic/29063-s4s-clutch-slave-cylinder/
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Integrator
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2,740 Posts
Thanks for your reply, I will give that a shot and see if there is any change. I am skeptical that there is still air in there but I suppose anything is possible. Ill let you know. Thanks for the FB shout out. Cars and Coffee was a blast!
What color is your fluid in the MC?
If it is black-ish, probably seals are going or gone already. DOT5 and most of the synthetic fluids will soften & dissolve rubber parts.
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Integrator
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2,740 Posts
My fluid was black, which is indicative of rubber parts dissolution. My master and slave cylinders were original Girling parts.
Original set worked for ~25,000 miles (13 years) and was rebuilt in 2012; slave in 2013. They failed again after only 5 years. Clutch fluid was black when I got the car. I flushed the system and filled up with modern DOT4 Castrol 12614B, but it turned black AGAIN.

I suspect that:
-rebuild kit rubber parts were inferior (source unknown, done by PO)
and/or
-fluid used was incompatible w/rubber parts of the system.

Last week, I have installed a new Wilwood compact MC and JAE aluminum (aftermarket) SC.

WHICH fluid should I use in my clutch?

There are some strong opinions that only Castrol 15172A GTLMA should be used in clutches, but it has been re-packaged.

Some past discussions: RE: GIRLING BRAKE FLUID
 

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Wingless Wonder
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5,552 Posts
Our clutch hydraulics have lasted a long time on Castrol/NAPA DOT 4.

Presently, we are running an original (never rebuilt) slave cylinder; :laugh2: replaced the clutch master in 1995 (rebuilt in 2017 with a kit from SJ).

Still have the OEM Red Clutch Hose fitted, too! :surprise: :surprise: :surprise:


+++++++++++

By coincidence, yesterday was the day that did our yearly brake & bi-yearly clutch fluid flush. The BF was almost as clear as new; the clutch fluid was a little darker but not terrible.
 

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Integrator
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2,740 Posts
Thank you Atwell.

Good article on Castrol brake fluid: Brake Fluid Tech ? Moss Motoring

I'm affraid I buggered up my clutch circuit by using a wrong Castrol fluid (black bottle)!
One Club Member told me that Castrol GT LMA (white/red/green bottle) should be used!
The LMA stands for low moisture absorption. The recent addition of the word Synthetic to the label caused some concern, but this fluid has always been synthetic. They added the extra word to the name when they changed the composition to raise the dry boiling point from 446 ºF to 509 ºF. Castrol GT LMA is suitable for use in any British brake system designed for glycol fluid. 220-455, 12 oz., 360ml
 

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Castrol has rebranded their DOT 4, it no longer says GTLMA but if you call them they will tell you it's the same stuff. The failure chain goes like this. The fluid is not changed for a long time. It absorbs moisture from the air and gets darker and darker. The boiling point drops as water is absorbed. The moisture attacks the internal metal surfaces of the cylinders causing corrosion and pitting. As the seals pass over the pitting they get torn causing the seals to leak and shed particles making the fluid darker and thicker. As the fluid leaks out, air gets in and the system functions more and more as a pneumatic system and less and less as a hydraulic system. You quickly reach the point where you depress the clutch and can no longer get full release. If you force shifts you damage internal parts of the transmission. The fix is to replace or rebuild (and resleeve) the cylinders. To stop the failure chain flush and refill the brakes and clutch at least every other year. Because most of our cars are not used regularly the brake fluid doesn't get hot enough to drive the moisture out so regular flushing with fresh stuff will prevent the pitting and corrosion.
David Teitelbaum
 

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Wingless Wonder
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5,552 Posts
Castrol has rebranded their DOT 4, it no longer says GTLMA but if you call them they will tell you it's the same stuff.
Hmmm, despite the label saying NEW FORMULA? :confused:


David's scenario of hydraulic system 'life' is a true one...Our Esprit was only 5 years/20K miles old when we bought it. The clutch master failed within months...and was rebuilt despite there being some pitting on the cylinder bore (that we smoothed out). That is why the rebuild didn't last, and we replaced the cylinder 2 years later.

+++++++++++
PS: the boiling point of Castrol DOT 4 (and the NAPA BF that I just purchased) has always been 311F. It meets SAE spec J-1704. Where did you find your quoted spec, MRDANGERUS? It's not on the Castrol site.
https://www.castrol.com/en_us/united-states/home/motor-oil-and-fluids/brake-fluids.html

PPS: The newest DOT4 is a low-viscosity type labeled SL.6 that is made for ABS brakes...
 

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1995 Esprit S4S
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205 Posts
Clutch Fork

Question, with the slave cyl. detached, how much play should there be in the clutch fork? should I be able to move it left, right, up and down?
 

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S4s
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662 Posts
Discussion Starter #51
@wohlmeyer

I remember my clutch fork being very floppy. More so than I expected, but I'm not a mechanic. I had to replace mine because the hardened steel clip that holds it to the ball joint (which is where it pivots) broke off. The new one went on way too easy and seemed floppy, but it seems to be the way they are because 5k mile later it is still good and working.
 

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Integrator
Joined
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2,740 Posts
BEWARE: DO NOT use 5/8" dia MC without checking specs carefully.

Some 5/8"-ers do not have enough stroke to fully disengage the clutch (working w/standard OE 7/8" SC). They have only 1.25" stroke and 0.39" volume.

260-2636
Bore Size 5/8"
Area (in²) 0.310
Stroke 1.40
Volume (cu in) 0.43



For example 260-15097 is 0.70" dia but HAS INADEQUATE STROKE and volume
Bore Size .70
Area (in²) 0.380
Stroke 1.25
Volume (cu in)0.48



>>>>>>>>>>>>>>>>>>>>>
ONLY 0.70" dia Wilwood PN# 260-6579 has a proper 1.4" stroke and 0.53" volume!
Bore Size .70
Area (in²) 0.380
Stroke 1.40
Volume (cu in) 0.53

https://www.wilwood.com/MasterCylinders/MasterCylinderProd?itemno=260-2636
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