plastic pedal bushings- which supplier?

[}{arlequin]

I'm going to begin rebuilding my brakes, starting w/ the pedal cluster. I would like to retain the plastic bushings but don't see them on Pelican. Anyone know where I can get them? Thanks.

[}{arlequin]

no one knows where they sell these?.... bump

[Grady Clay]

Dave,

Here is the diagram.
"
"
(C) Dr. Ing. h.c. F. Porsche A.G.

You will need the plastic bushings:
(2) #47 901.423.542.00 “Mounting bush”
(2) #36 901.423.341.00 “Mounting bush”
(2) #28 901.423.253.00 “Mounting bush”

You should also replace the roll pin:
(1) #42 900.309.002.00 “Spiral pin”

If the hinge has wobble, replace the accelerator pedal.
(1) #1 901.423.010.00 “Accelerator pedal”

These are the OE parts from Porsche.
These part numbers are from the ’72-’73 paper parts manual.
They may supercede to later numbers.

Best,
Grady

[Jdub]

You're kidding, right? You'd keep those horrid plastic bushings when you could move to bronze?

Seriously: why?

John

[}{arlequin]

Well, as mentioned in other threads (Warren's, Grady's) and through my current experience, it provides a warning to an imminent problem. (If it didn't happen to me in such a manner, I wouldn't be such a proponent and would have gone, eventually, w/ bronze too.)

Whether it's a leaky master, or some other damaging moisture, it will affect their performance and tell me something's going on. In a blind test, when new, I doubt anyone can tell the difference between bronze and plastic. Not sure what their lifespan is, but I'm sure they will last until I forgot that I even changed them.

(Thanks Grady, does that mean that current Porsche dealerships should have them, or just automotive stores?)

[Grady Clay]

John,

Dave is correct. The plastic bushings are susceptible to swelling if the master cylinder leaks brake fluid on them. This causes the pedals to become slightly “sticky” and you notice there is some problem.
The problem usually is a slow leak of the master cylinder until it either runs out of fluid or suddenly fails. The brake warning light can be too late.
It is not a bad idea to service all these parts every 5-10 years anyway. The bronze bushings can wear out also.


Dave,
Some “while you are there” items.
This is a good opportunity to replace your clutch cable. The front is more difficult to get to and you have it off.
Install a new brake light switch #25.
Carefully inspect #37 and #39, the clutch arm and shaft for damage where the roll pin #42 is. It is not too unusual to have to replace these parts.
Replace the plastic bushing #38 901.423.343.00 “Bush” in the clutch shaft and inspect the shaft bore for damage.
All the parts may need cleaning and repaint. You don’t need anything fancy.
I usually replace the pedal pads at the same time.
I reassemble everything with molly or lithium grease.

The areas of difficulty you should anticipate are the two bolts that hold the accelerator pedal to the floor may be difficult to remove. Reassemble with new hardware and grease the threads.
Another difficulty (the big one) is removing the roll pin #42 and getting the arm #39 off the shaft #37. Be prepared to take the pedal assembly to someone with a torch and a press. It is a five minute job with the right tools.

A word of caution. Porsche changed the #37 shaft several times over the years to change the lever ratio. Be sure to match the replacement part if replacement is necessary. The part you want is 911.423.027.01 “Clutch pedal shaft.” This and other subtle differences can be an issue if you replace the entire pedal assembly.


Yes, these are usually only available from PCNA parts system but I would call our host first. Most good indys will stock these. I would insist on them in the original Porsche wrapping.

Best,
Grady

[Jdub]

I'm a huge proponent of the clutch cable/new trunnion pin/bronze bushings (and horseshoe spring as applicable) redo. That said, if I'm going in, I'm going in to replace it with the best possible, and forget the canary in a coalmine mindset. In fact, I use an trick where the brass bushings are heated in 80/90w prior to use. Taught to me by a Norton mechanic when rebuilding the gearbox.

I still don't get it, but I do have an appreciation for going stock. I will agree that I doubt I could tell the diff. between two identical pedal racks with one plastic, one brass.

John

[Grady Clay]

John,

That is a great analogy. I never thought of it as a “canary in a coal mine,” perfect – and true.

I agree, you can’t tell the difference between plastic and the trickiest bronze bushings when everything is correct. This is an area of a 911 that should be serviced periodically. I would rebuild the pedal assembly annually on a track car and every 5-10 years on a street car unless there are adverse conditions. That schedule wouldn’t differ if bronze or plastic.

I still like the idea of the plastic canary.


All of our 911s are up to 40 years old. We should not expect everything will last into the 22nd century. Even in the best of conditions, a 911 is in a harsh automotive environment. I am a proponent of PREVENTITIVE maintenance and repair. I’m not going to risk my life and limb (or 911) on a 30 year old master cylinder or ball joint pinch bolt. Some serious maintenance is required in areas that are not on your 3000 mile schedule.


Best,
Grady

[Schrup]

Originally posted by Grady Clay
John,

Dave is correct. The plastic bushings are susceptible to swelling if the master cylinder leaks brake fluid on them. This causes the pedals to become slightly “sticky” and you notice there is some problem.
The problem usually is a slow leak of the master cylinder until it either runs out of fluid or suddenly fails. The brake warning light can be too late.

I'll put my 2 cents in, I rebuilt my pedal cluster with brass & I'm glad I did because I developed a master cylinder leak & it became apparent when my brake peddle became slippery. My situation might be unique because I don't have any flapper boxes so the fluid has a more direct path. But I wouldn't have wanted to have to replace those bushings again 2 months after putting new ones in.

[RoninLB]

fwiw, I use stainless metric bolts for the pedal fastners and keep the old, but still good, clutch cable in the trunk.

[}{arlequin]

Paul, that makes sense. I wouldn't want to dive in there 2 mos later either. My plan is to replace the master if it's leaking or looking old, that way maybe it won't be happening for a long time to come. *Something* is causing my bushings to bind (brake switch is also acting up so the whole area needs attention) and I'll know more when I take out the cluster.

I end up giving away my clutch cable to some stranded soul, then when I need one it's missing. Maybe I should start carrying 2...

[Schrup]

Dave, I wish I would have upgraded to a Turbo master cylinder when I replaced mine, didn't find out about this trick till after the fact.

[}{arlequin]

I'm still on the fence about this too. I have stock brakes (steel M calipers) on 3" ears. They have been more than adequate (never faded in 3 DEs and I didn't even change the fluid) since my car is light and not very powerful. Right now I can't go to the expense of new struts so I will not be upgrading the brakes until a bigger motor warrants it. Then I'll head in the 930 direction.

Since I'm leaving the brakes stock I'm not sure what I'll be gaining, other than a harder pedal, by going to the 23mm. I don't mind the effort, but I'm not sure if I should.

[RoninLB]

Originally posted by }{arlequin
Since I'm leaving the brakes stock I'm not sure what I'll be gaining, other than a harder pedal, by going to the 23mm. I don't mind the effort, but I'm not sure if I should.

I brought this up to Bill Verburg.. I'm not doing it on stock[S caliper] brakes.

[Gunter]

Paul: Why Turbo? Would a Turbo MC bolt right in? What about the two brake light switches on the stock SC MC?

[Schrup]

Gunter, from what I've been told, it does bolt right on & has the switches for the brake lights. It would have been nice to do when I needed to replace my M/C before the prices went up & have it in place for when I upgrade my brakes. Have I been misinformed?

[Gunter]

What would be the advantage? Are the plunger/seals bigger? Are you changing the standard SC 2-piston calipers to 4-piston in the front? If you do, you may need a proportioning valve for the rear.

[Schrup]

Gunter, I'm not sure what I'm going to do yet. I would think that the 930 calipers all the way around would match up to the Turbo M/C. But I may end up installing a Tilton valve no matter what I do. That upgrade is still at least a year away though, I haven't learned to out drive the brakes I currently have & will not upgrade untill my skill level warrants it. As always, thanks for your input.

[}{arlequin]

Gunter, here is my recent brake thread w/ Bill's input. The second link is a very good progression of brake upgrades, starting from the lowliest to the many combinations of Big Reds.

more brake musings ad nauseaum

http://home.nycap.rr.com/wmv/generalbrmd.htm

[RallyJon]

If you go from the stock MC to the 23.1 MC without changing anything else, your pedal effort will increase ~46% for the same braking. This is a quick back-of-envelope calculation, but it looks like you'll get a rock-hard pedal and have to push like Schwartzenegger to slow down.

Generally, you move to a large MC when needed to keep up with a larger caliper piston area.