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  Topic Review (Newest First)
07-30-2019 01:04 PM
MRDANGERUS 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 (in) 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 (in) 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 (in) 0.380
Stroke 1.40
Volume (cu in) 0.53

https://www.wilwood.com/MasterCylind...temno=260-2636
.
07-11-2019 05:35 AM
Seraph @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.
06-30-2019 06:17 PM
wohlmeyer
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?
06-27-2019 10:47 AM
carbuff EDIT: I see that some of the low viscosity DOT4 SL.6 fluids have the higher boiling points that MrD mentioned. Here's a convenient comparison (no Castrol, though):

https://www.fcpeuro.com/products/sl6...-liter-ate-sl6

Chart midway down the page...
06-27-2019 10:30 AM
carbuff
Quote:
Originally Posted by jtrealty View Post
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?


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...ke-fluids.html

PPS: The newest DOT4 is a low-viscosity type labeled SL.6 that is made for ABS brakes...
06-27-2019 08:33 AM
jtrealty 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
06-27-2019 08:24 AM
MRDANGERUS 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 F to 509 F. Castrol GT LMA is suitable for use in any British brake system designed for glycol fluid. 220-455, 12 oz., 360ml
06-27-2019 03:50 AM
carbuff Our clutch hydraulics have lasted a long time on Castrol/NAPA DOT 4.

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

Still have the OEM Red Clutch Hose fitted, too!


+++++++++++

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.
06-26-2019 09:40 PM
MRDANGERUS 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
06-19-2019 07:17 PM
wohlmeyer Clear fluid. Ive only ever used superblue dot 4.
06-18-2019 11:14 AM
MRDANGERUS
Quote:
Originally Posted by wohlmeyer View Post
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.
.
06-17-2019 07:57 PM
MRDANGERUS
Master Cylinder, Esprit

Quote:
Originally Posted by wohlmeyer View Post
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/f16...37/index2.html
and
https://www.thelotusforums.com/forum...lave-cylinder/
.
06-17-2019 07:45 PM
MRDANGERUS
Quote:
Originally Posted by Seraph View Post
Thanks for the additional info. I'll make some adjustments tomorrow to the pedal. The only thing I can read clearly on the master cylinder is "GIRLING70" so I'm assuming it is .70.
Pelican and Bimmers website praise Wilwood MC-s, they are internally anodized.
06-17-2019 11:29 AM
wohlmeyer
Quote:
Originally Posted by carbuff View Post
Bill,


Try to bleed the clutch one more time with the cylinder 'dismounted', hanging down by the hose (bleeder at the top).

Reinstall, then prop the pedal down overnight.

Post back with results.



PS Just saw your pics on FB. NICE.
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!
06-17-2019 11:27 AM
wohlmeyer
Quote:
Originally Posted by jtrealty View Post
If you can't get into reverse it is because you are not getting full release from the clutch. The reverse gear has no syncros so you can't shift into it if the transmission is still turning because the clutch has not fully released or the rear wheels are spinning. Either you still have air in the clutch hydraulics or you need more throw (movement) of the slave cylinder. Or your clutch is so worn that you can't adjust anymore. Try shifting into reverse with the E brake on so the wheels are not spinning. It can be hard to get all of the air out so it may still need more bleeding. To prevent things from leaking you should be flushing and refilling the brakes AND clutch at least every other year with Castrol DOT 4.
David Teitelbaum
Thanks for your reply. I have always maintained the hydraulics for the brakes in the manner you discribed, I havnt been so great with the clutch hydraulics. I did replace the master 4 years ago and had the entire system flushed 2 years ago but that is about it until I replaced the slave and lost reverse in the process.
06-17-2019 09:50 AM
carbuff Bill,


Try to bleed the clutch one more time with the cylinder 'dismounted', hanging down by the hose (bleeder at the top).

Reinstall, then prop the pedal down overnight.

Post back with results.



PS Just saw your pics on FB. NICE.
06-17-2019 09:00 AM
jtrealty If you can't get into reverse it is because you are not getting full release from the clutch. The reverse gear has no syncros so you can't shift into it if the transmission is still turning because the clutch has not fully released or the rear wheels are spinning. Either you still have air in the clutch hydraulics or you need more throw (movement) of the slave cylinder. Or your clutch is so worn that you can't adjust anymore. Try shifting into reverse with the E brake on so the wheels are not spinning. It can be hard to get all of the air out so it may still need more bleeding. To prevent things from leaking you should be flushing and refilling the brakes AND clutch at least every other year with Castrol DOT 4.
David Teitelbaum
06-16-2019 11:40 AM
wohlmeyer I know this is an old thread and I have read through all of it. I have the same issue only I didn't replace the clutch, I replaced the clutch slave with one from SJ (not a lotus part) because mine was leaking. Now I cant get the car in reverse and there were no issues getting it in reverse before I replaced the clutch slave. I have tried the abutment screw and have spanned it from 9-12mm and then back to 10mm and I do not see any difference no matter where I have that screw set. With the clutch pressed to the floor, I can put it in first and the wheels start to spin (car is on axle stands). I cant get in reverse at all (unless i turn the engine off and start in reverse). I have bleed the heck out of the system and I am not getting anymore bubbles. I can spin the clutch slave piston rod by hand. Should I also be able to press the piston rod into the cylinder by hand (because I can)?

Thanks

Bill
12-14-2017 08:54 AM
carbuff ^^^ I've had that happen to me. Now, I don't even measure the new one.
I always just use the pushrod from the old master cylinder.

Reduces the time spent in the Lotus Position.


++++


Another Clutch System tip: Make sure any cylinder's fittings are the same size. (Ask before ordering)


JAE can provide adapters of many configurations.
12-14-2017 07:57 AM
Seraph FYI.

If you buy a replacement clutch master cylinder, be sure to measure the length of the push rod. It'll save you quite a bit of time from not having to reinstall it twice.

New clutch master push rod was 20mm shorter:
This thread has more than 20 replies. Click here to review the whole thread.

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