911SC Throttle Body

[booyah911]

Posted this yesterday but it didn't go through, second attempt. I'm reconditioning the throttle linkage on my '82 sc, from accelerator to throttle body. There were literally no bushings left. I purchased these but at the throttle body I'm seeing a wallowed out hole in the linkage supporting final ball socket. The ball sock connects to another linkage that contacts the idle switch. Is there supposed to be a bush here (see arrow)? If not, is this repairable or do I need a new throttle body? Any help would be appreciated!

[Nditiz1]

So this ball is punched into the arm. You have 2 methods to go about it.

1. Get a dremel cut off wheel and sheer it to remove both halves. Then use the bellcrank rebuild kit to add the ball to the end with a nut on the backside where the factor would have punched it to secure it.

2. Remove the arm (not sure if it can be done in place). Replace the ball end with a repair kit. EDIT: I looked at it again and the arm is attached to the throttle shaft so unless you want to remove the entire throttle body I would go for method 1.

[David Inc.]

Isn't that ball directly attached to the throttle arm? It only passes through that hole which is for other attachments, but that hole having slop shouldn't impact the throttle action.

Mine has a similar gap without issue, both arms are fixed to the butterfly shaft so that hole doesn't do anything...I think...too effing cold to go check the car in the garage though.

[booyah911]

Interesting about the bell crank rebuild kit. I'll have to look at this. Is it possible to remove the throttle body without dropping the engine?

From what I'm seeing, this will cause slop in the throttle input. The ball passes through the throttle arm and is attached to another, backside link that is used to press against the idle switch. The shaft of the ball bears against the hole in the throttle link. You can see the ball in two different positions within the wallowed-out hole in the pictures below

link

[booyah911]

So I went out and looked at this again and both links are attached to the throttle butterfly. The throttle arm is keyed and the link that contacts the idle switch is just a follower. I agree it looks like the throttle input would not be affected because the throttle arm is tensioned by the spring. The other arm has the play at idle. I was looking to see if there is a known fix for this. If not, I guess I can just move the switch down and be sure it is making contact when at idle.

[David Inc.]

You can also adjust the switch a little or bend its arm, easier to do that.

[Baby]

My 83 looks the same as yours. It is not a precise fit. You should be able to pop that socket off the ball with a couple fingers to have a closer look. Seems unlikely that the hole in the throttle arm is out of round, but if so it might be hard to adjust by bending the switch arm, if adjustment is necessary.

[Funracer]

Originally Posted by booyah911

Is there supposed to be a bush here (see arrow)? If not, is this repairable or do I need a new throttle body? Any help would be appreciated!

No bushing. The hole is enlarged so that the off idle switch will richen the mixture a bit just prior to throttle movement off idle. That’s the way it looks on my 83SC as well. In fact I believe the throttle linkage should be adjusted so that the arm makes the ball touch the upper edge of the large hole with foot off the throttle. Then when you roll on to throttle it moves just a tiny bit enough to click the off idle enrichment switch and then just afterwards opens the butterfly. In your picture the ball is touching the lower edge of the hole, so I would lengthen the rod one turn maybe.

Just my opinion though.

[booyah911]

Thanks for the help, guys!

[Nditiz1]

I just went out and looked at my 82 engine and I have no slop. I looked at the extra throttle body I have. No slop. The ball is punched from the other side to be a solid fit.

Edit: I don't know what Porsche did, they have a bunch of different designs for the SC throttle body...

[booyah911]

Thanks for the follow-up, that was my sense when I first saw it. There's no way the oversized hole would be a design feature. Must be wear. It seems like the repair would involve more than just replacing the ball. The hole the ball passes through (on the throttle link) would need to be narrowed, which would require a new link or welding it up and drilling it to the correct ID. Two questions: (1) can the throttle body be easily removed with the CIS in the car, and (2) any interest in selling me your extra throttle body??

[Nditiz1]

PM'd you Booyah

[Funracer]

Originally Posted by Nditiz1

I just went out and looked at my 82 engine and I have no slop. I looked at the extra throttle body I have. No slop. It should have no slop I don't care what anyone says. The ball is punched from the other side to be a solid fit. As I stated before you can repair it if you want, but the linkage should be tight from the pedal to the throttle.

How many miles on your 82? My 83 has over 100k but I have seen several pictures today of TBs on ebay and Pelican and all have the enlarged hole. Can you post of pic of yours? If mine is worn that would be good to know.

Thanks

[Nditiz1]

I did the same thing as you today haha. So 2 of mine in the for sale section as well as the one on my 82 (euro) are 248.02 part number. Apparently there are several part numbers for the SC 78-83
248.02
248.04
248.11
248.12

The .11 and .12 seem to have the pressed on throttle arm where as the .02 has a nut on the end. The .02 seems to be for 78/79 US and 78-83 Euro - so all non lambda.

This .11 on ebay has what appears to be a non widened hole
https://www.ebay.com/itm/143094403302?chn=ps&_trkparms=ispr%3D1&amdata=enc%3A1ceBQAM7YQEy1oetGmwdJgw80&norover=1&mkevt=1&mkrid=711-117182-37290-0&mkcid=2&mkscid=101&itemid=143094403302&targetid=1644837434843&device=c&mktype=pla&googleloc=9007878&poi=&campaignid=20125739985&mkgroupid=149128855676&rlsatarget=aud-1297930287258la-1644837434843&abcId=9312975&merchantid=6514684&gclid=CjwKCAiAkp6tBhB5EiwANTCx1JWGKLTSQp82toy1j7_T ylkkp8_VzwpCaWeUiNB-ltot0gb5Se6_bRoCptMQAvD_BwE

This .12 on ebay has the rounded hole
https://www.ebay.com/itm/164669446065?chn=ps&norover=1&mkevt=1&mkrid=711-117182-37290-0&mkcid=2&mkscid=101&itemid=164669446065&targetid=1645685073288&device=c&mktype=pla&googleloc=9007878&poi=&campaignid=20133407470&mkgroupid=147476396765&rlsatarget=aud-1412318123216la-1645685073288&abcId=9312979&merchantid=7925764&gclid=CjwKCAiAkp6tBhB5EiwANTCx1IaUa8bSK9UEBeskm_TB hrWx7MJS3jk26ZWD_xmJDykQeKoAZYUOvxoCAhkQAvD_BwE

Every single one I have looked at with the nut on the end of the shaft has a non widened hole.

I don't know about the widened hole and enrichment, but it seems like a hokey approach to throttle.

[booyah911]

Yeah, I'm not sure now. It may indeed be a design feature. My '82 has over 100k as well.

Nditiz1, the first ebay link, and I think the one's you have for sale, do not have a separate link that touches the idle switch. These have a single throttle link and the ball is attached to that.

The second ebay link has both links and a wider hole through the throttle link.

[booyah911]

Here is the single link design, which doesn't have a pass-through hole that we're talking about.

[Nditiz1]

Now I see it. I guess Funracer and the others are correct it is by design. I resign my fight on that it is worn and should be tight.

[pmax]

Don't understand why the outer arm for the CC lever needs to be extended to the ball and socket, and with a slop, when it is already attached at the pivot.

[booyah911]

The ball attaches to a link that is not keyed to the butterfly shaft, so it is not "already attached to the pivot," as you say. The ball (attached to the non-keyed link) passes through the oversized hole in the throttle link that itself is keyed to the butterfly shaft. So the socket pulls on the ball, the ball bears against the throttle link, and the throttle butterfly opens.

I've played with the assembly and don't think this causes any actual slop in the accelerator pedal. The ball is always pressed against the oversized hole by the spring on the throttle link, so there is no dead movement in the accelerator pedal before the butterfly link moves. I CAN move the non-keyed link up and down within the limits of the oversized hole, which changes how this link bears against the idle switch. I'll try to shoot a quick video to visualize this, but I think the assembly is functioning as intended and I just need to make sure the idle switch is properly positioned.

Hopefully this discussion helps someone in the future. My goal was to remove all slop in the accelerator linkages so that the accelerator pedal translated to direct movement of the butterfly. All of my bushings (and I mean all of them) were missing, so my accelerator was entirely disconnected from the engine. This assembly at the throttle body just threw me for a loop.

[pmax]

"The ball attaches to a link that is not keyed to the butterfly shaft"

OK, makes sense ... answers my question on why the outer arm , attached to the pivot, needs to be extended to where the socket is.

"The ball is always pressed against the oversized hole by the spring on the throttle link, so there is no dead movement in the accelerator pedal before the butterfly link moves"

I'm guessing the oversized hole is simply there to fit the CC arm over the ball during assembly. But still, the single arm variant appears to be a better design which guarantees no "slop" and has no wear and tear concerns of the two arm.