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Another clutch question

sunny67

Silver Level Sponsor
I’ve seen some post similar to my issue but not seen a resolution. I’ll apologize in advance if I missed an answer. My clutch engages at the extreme end of its travel, to the point where my knee is near the steering wheel (I’m 6’4”). I would guess it engages in the last inch or so of travel. The clutch does not slip and everything feels solid. The rod is in the hole closest to seat. The pedal rests at the same level as the brake pedal. The clutch master cylinder looks like a stock unit. Is this normal. It sure doesn’t feel right but I’m used to driving classic American muscle cars. If it’s not normal, does anyone have a solution?
 

puff4

Platinum Level Sponsor
Assuming the hydraulics are working well, the higher a clutch engages/disengages, the more wear there is on the clutch disc. So, my guess is that your disc has become thin and is due for replacement at some point. No hurry, so long as it’s still grabbing ok, but I’d start looking for the parts.
 

mxp01

Platinum Level Sponsor
Quick back story. In 2015 I replaced my pressure plate, clutch disk, and release bearing.

Just last February of 2021 I pulled my engine out for a refresh. Before I pulled it out I went ahead and ordered a new clutch disk and release bearing. My thinking is I'm already there why not, they aren't very expensive. After 6 years of spring, summer, and fall driving there was very little wear on the disk and bearing. I still went ahead and replaced the disk and bearing with the new ones and stored they slightly used ones away.

After saying all that, I would say my foot comes about 2/3 of the way up before my clutch engages. I have had two clutches fail on different vehicles in the past and both of them began to show signs of slipping before completely failing altogether. So yes, if it's not broke don't fix it.
 

greenbeam

Platinum Level Sponsor
There are different height clutch plates (spring/diaphram types), different height throw-out fork pedestals, and throw-out forks. It maybe that a previous owner has tinkered and found a combination that 'just' works.

You might start by checking what is original for your model (1967?) - eg, full synchro, fine spline 'box?, then is it the right type of pressure plate - may be able to see with an inspection cam through the hole in the bell-housing, and maybe measure the pivot pedestal height through the hole too and report back to see what height others have.

At least then you'd know if you have a 'stock' setup before you go pulling things apart.
Good luck!
Paul.
 

Gumby

Donation Time
What it really comes down to, regardless of the installed parts, is Free Play. Both at the pedal, and at the throw out bearing arm.

You should have a bit of free play for the pedal at the top of it's travel. Meaning that there is no pressure being applied to the clutch master in its relaxed state. The plunger rod for the master needs to be fully extended (withdrawn from the master) so that the inner plunger is up against the snap ring stop within the master cylinder. This is important for two reasons, well three really. 1 Fluid return, Fluid refill, and no pressure applied to the Slave cylinder, causing the throw out bearing to be engaged. Check it and make sure there is some free play in the pedal.

Then check that there is some free play between the slave cylinder as well. You do NOT want the throw out bearing pushing on the clutch cover when the pedal is not pressed. If there is contact and pressure, the bearing will wear prematurely, and if there is significant pressure on the bearing, The pressure plate can not exert its full force on the clutch disk, which will lead to premature wear from slipping, or slippage itself, and clutch engagement right at the very end (top) of pedal travel.

If there is no free play, adjustments need to be made.
 

sunny67

Silver Level Sponsor
I’m doing a follow-up reply to my own post so if anyone has a similar issue in the future, they will see my resolution.
It turns out that the existing clutch master cylinder had a 3/4” bore instead of a 5/8”. As a result, when the pedal is pressed, an higher volume of oil is transferred to the slave causing it to disengage the clutch quicker. I replaced it with the proper 5/8” bore and now it’s working as expected.
 

Jay Laifman

Donation Time
Interesting. Some people report getting the 3/4" because they don't get full release at the other end. As Greenbean says, there are a whole lot of parts with different sizes that can be in there and cause these differences.
 

jumpinjan

Bronze Level Sponsor
The 3/4" bore M/C is for the brake servo setup. The early Alpines used the smaller bore (0.707", I think it is).
If you are not using the brake servo, you need to use the early M/C to get the braking power back.
By the way, the hydraulic clutch system will always adjust it's self, which is not like a mechanical linkage setup. So, don't expect much free play in the pedal.
Jan
 
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