915 clutch spring retrofit

[Yoda]

Here's a question for the technical types: The clutch on my '75 is very heavy, to the point of being annoying in stop and go traffic. The '83 is much lighter and easier on the left leg. A significant part of that is the helper spring on the newer version of the tranny. Is it possible to retrofit the newer helper spring onto the older transmission? I haven't crawled under the cars to look yet, but thought I'd ask here first. Haven't found anything on line, either. (And I did use Search :D)

Brent

[Jase007]

Brent:

Something is probably wrong with your '75 setup.

I have the same setup on my '76 [no omega spring] and it isn't a difficult clutch pedal. Not butter like a Honda or BMW hydraulic but ... not difficult.

Off the top of my head:

1. Check clutch return spring isn't broken [mongo one off of clutch pedal arm to base - VERY tough to install solo]. Mine broke around ~2001 with ~ 140,xxx miles on the car. Was the original one.

2. Check pedal cluster bushings. Original plastic ones bind. Rebuild cluster with brass / bronze ones.

3. Install new clutch cable [yours is probably original ...?]. Is cheap and you can lube it up.

4. Check clutch adjustment [very simple on our setup].

5. If that isn't it ... start running some stairs to get the leg strength up :lol: ;)

[rs911t]

What Jase says. Your situation sounds backwards.

I plan to retrofit a '80 915 into an '72, and was told to use the clutch lever assembly from the '72 or I'd end up with a very heavy clutch, e.g. the omega spring.

[Jazzbass]

To your original question, no it's not (easily) possible. There are no mounting points for the omega spring on the early trans.

[Trak Ratt]

Also, the release arm itself is attached to a shaft the turns in bushes in the bell housing. These can rust up over the years too.

[smdubovsky]

Even the bronze bushings can freeze up if not taken care of. The teener has them and the last time we moved the car in the garage a friend said "your clutch pedal stuck to the floor." When I took the whole cluster out there were 2-3 cups of gunk down there. The cluster was seriously grungy + flaking paint so I sent the whole thing off for powdercoat & replating. Just got it reinstalled this weekend. Now the clutch action is MUCH better.

[Yoda]

Thanks for the replies. The clutch effort on the '75 is probably twice what the 83's is, to the point my wife won't (can't) drive it. Over the last 20 years, I have done all of Jase's recommended upgrades (including no. 5 :) ), with no appreciable difference in clutch force. It has had at least two clutches, a new clutch cable and a new transmission. At least two pros have looked at it and have been unable to find anything wrong, although they though it was heavy too. I do wonder if I might have a weak or incorrect return spring, though. The car was seriously modified by a previous owner, so anything is possible.

[smdubovsky]

You say its had clutches and a transmission and the car was "seriously modified" by the PO. What pressure plate is in there? Upgraded ones usually take more force to disengage (where do you think they get the extra clamping pressure from.)

Look on the bright side:) Even w/ a broken helper spring a 911 is still easier to shift than a mid 70s E150 van (I would get leg tremors holding that one down at a light. To the point of often using my arm to push down on my knee to lock my leg straight.)