Accelerator pedal fail

[RobFrost]

There is a knack by which my 1970 911T can be driven without the accelerator linkage popping off, leaving the driver with no power. It would be preferable not to have to concentrate on that while driving. There are three obvious fails:
- The top of the pedal has free movement in two dimensions, left to right being the dimension that I assume is not factory original spec. Anybody know the cause of this or what is supposed to prevent lateral movement of the pedal?
- The first socket in the linkage pops off its ball if the pedal is allowed to move to its left leading to zero throttle - I assume the ball joint is worn. Anybody have experience of worn balljoints and whether replacement of the socket fixes it?
- There's a lot of play in the whole system and it's prone to settling in other than zero throttle position, leading to a challenging driving experience. It looked up on the ramps at the MOT like there's a linkage on or near the bottom of the gearbox which might have something to do with the accelerator. It had a hold about 13mm across with a rod in it having about 5mm play either side. Could that be the problem and is there meant to be a bush
in there?

I've seen the brass bushing kit available and how that fits, but none of that seems relevant to these three problems.

[911hillclimber]

From my 1973, so your might be different..
The pedal is mounted to the floor and flexes only to and fro, no lateral/side movement at all. I suspect the lateral movement is allowing/forcing the short rod to op out.

The bottom of the pedal is mould to act as a hinge, is it torn/cracked?

The link to the side of the box is usually a long rectangular loop with an indent in the slot length, the link is meant to be working on the bust at it's exteme length, ie it is tight. This link runs up to the carbs/injection lever and that usually has a very long return spring to bring the carbs back to tick-over position. All the linkages must be loose even with some clearance, 0.25mm or so to assure free movement. All these clearances can add up but the linkage should return to a repeatable 'zero' position so assuring steady tick over return.

You need to follow the entire linkage through correction every bit you find sloppy.
When right, the throttle feel is very positive, just as you would expect.

[210bhp]

The pedal should be firm. Look under the carpet and you will see how it is fixed at its base. The other issue with the ball and socket behind the pedal is not an uncommon problem and this could just be wear of the socket. I would fix both of these issues before tampering with anything in the engine compartment.

Regards
Mike

[chris68]

Probably a good idea to re-bush the pedal assembly and get a replacement throttle pedal. You're always welcome to take a look at my car for comparison.
Cheers

[911hillclimber]

IIRC some of the early cars have a pedal covered in rubber, and that forms the hinge too. Mine is from 1973, the original, and all is ok. Others, I suspect later, are plastic.

[RobFrost]

Probably a good idea to re-bush the pedal assembly and get a replacement throttle pedal. You're always welcome to take a look at my car for comparison.
Cheers

Thanks Chris. Sounds like the pedal itself is what stops the lateral movement so I'll try a new pedal. It looks iffy at the base where it connects to the floor.

[Dougieboy1]

Apparently later socket ends on the linkage have some pin that prevents the ball and socket linkage falling apart.

The reason i know this is mine fell apart on the way to a Goodwood breakfast a couple of months ago - i pushed it back together and spent the rest of the trip worrying it might come apart. Local porsche guy fitted these later sockets and said it wont happen again..... And i had previously replaced all the pedal bushings, rod ends and the bell crank so it wasnt wear that made it come apart....

[hot66]

my pedal has had lateral movement for at least the past 18 years .. the rubber pedal around the floor bolts is soft allows this. I will be honest and say I've been meaning to replace this pedal for years just never got round to it . I've never had the rod pop out though

[Simon Rudge]

As everyone has said!

The bit not mentioned is to check the condition of the clear plastic bushes/guides that support the long rod on its journey down the inside of the tunnel, cant remember if there is 3 or 4 of them. This can make the operation sticky and horrible.

Poxy job to do, but the parts are cheap!!!!

[RobFrost]

As everyone has said!

The bit not mentioned is to check the condition of the clear plastic bushes/guides that support the long rod on its journey down the inside of the tunnel, cant remember if there is 3 or 4 of them. This can make the operation sticky and horrible.

Poxy job to do, but the parts are cheap!!!!

Thanks. Does the cable just slot into these? These aren't the ones you can get copper replacements for that ease the pivoting of pedals, right?

[Dougieboy1]

They are small plastic bobbins that are held into the transmission tunnel by metal tabs. As simon says, 3 of them.

See the diagram from Richard's excellent Safety Colours website, they are item 30.

https://www.safetycolours.com/porsche-9 ... lex-cables

They are a bit of a faff to fit but if they are knackered or missing, that wont help with the smooth operation of the rod.

[RobFrost]

They are small plastic bobbins that are held into the transmission tunnel by metal tabs. As simon says, 3 of them.

See the diagram from Richard's excellent Safety Colours website, they are item 30.

https://www.safetycolours.com/porsche-9 ... lex-cables

They are a bit of a faff to fit but if they are knackered or missing, that wont help with the smooth operation of the rod.

Are these the ones? https://www.design911.co.uk/fu/prod1492 ... 1-65-89_2/

[Dougieboy1]

thats the one or should i say thats the three.

unfortunately you will need to remove the hot air panel at the rear of the tunnel and the handbrake i think to get to the middle 1. The front one is accessible via the hole at the front of the tunnel and obviously needs the carpet lifting.

If i were you, i would check with a borescope first through the hot air panel to see if you actually need to do it as it is a faff.......