When the throttle linkage coupler breaks

W Scott Shores · 07-24-2006, 06:36 PM

... in the middle of the Arizona desert.

As I was driving from Los Angeles to southwestern Colorado for the 911E Registry Tour de Colorado a few weeks ago, I came upon some slow trucks and had to grab fourth, then third gears on the I-40 to make the pass. The throttle went to the floor and I lost all power. I managed to pull over to the shoulder. The car was idling. That's good. I turned it off and looked under the car and could see the throttle linkage dangling there just in front of transmission. I can see the problem, but can't reach it. Damn.

Since then, I've learned that these old rubber couplers have been superceded by Porsche to this improved part, now made of rubber AND metal. My rubber coupler had broken in half after 36 years of use. I need to get to a hoist to wire it back together, so I pulled a MacGyver and used a bottle cap and duct tape to wedge open the throttle over the microswitch to give the car about 4000 revs.

I hobbled along the shoulder at 25mph for the next 40+ miles before finally arriving at the first town, Seligman AZ. The Route 66 Repair Shop was closed for the night, so I checked in to the Route 66 Motel, before heading to the Route 66 Roadkill Cafe for dinner.

The next morning, we lifted up the car and made the repair using wire and a clamp.

This fix needed to last me another several hundred miles to Durango CO, through the mountains for the Saturday drive, and back again to Los Angeles. It held up perfectly!

After getting back home, we repaired it with the new and improved part and a new boot. And this is what it looks like now.

The moral of the story: if you have an old 911 that still has the all-rubber coupler, this is a worthy upgrade. And if your old coupler breaks in half in the middle of nowhere, a temporary repair using wire and a clamp works great!

WHCJr72S · 07-24-2006, 07:35 PM

I had that happen to me last year. I found a piece of wire, jacked up the car and repaired it. I posted on the early S board about my experience.

Mad Mike · 07-24-2006, 09:30 PM

Fantastic thinking in the middle of nowhere. I was thinking of shoe strings, which I have heard of before.

Good work!

Grady Clay · 04:51 AM

Scott “MacGyver,”

Good fix.

Can you take some good images if the two halves of the broken part? That is one thing that is missing on this thread:
”Throttle Cable Snapped....on my '68 911L....i think”

If you will post the pictures here, I’ll edit it into the correct spot.

One thing this illustrates is how important the floorboard and throttle stop are. If the stop is adjusted too far down and stresses the linkage at full throttle then this is the result. The same is true for a too aged plywood floorboard. It will bend with the same result.

An important part of regular maintenance is to fully depress the accelerator pedal as if you were trying for that last HP in a pass. At full throttle on the pedal, someone should still be able to move the throttles at the carburetors. They shouldn’t be at the stops. Stressing the linkage will still cause the updated accelerator cushion to fail.

Sorry I didn’t get to Durango to meet you. I was enjoying the company of the French family (Pelican Thrown hammer) in Colorado Springs. I had hoped to get them to spend the weekend in Durango but “Back Home in Indiana” (work) was calling. Next year.

Best,
Grady

W Scott Shores · 07-25-2006, 07:33 AM

Bill,
My friend on the phone referred to your post the night of the incident to confirm that a wire fix should work. That inspired me to write this post so it would be in the archives for future reference.

Mike,
I can always count on my brother to give me a bump!

Grady,
We missed you in Durango and sure do hope to see you there next summer! Unfortunately, I don't have any more photos of the broken piece to add to the other post.

Type911 · 07-25-2006, 11:37 AM

Scott,

It was a great trip eh?

Pretty amazing even with the old part that the coupler lasted all those years/miles. I have the updated part, but can see I need
the new rubber boot too.

I found these pics for your scrapbook

Wayne 962 · Wayne 962's Garage

Quote:

Originally posted by Grady Clay
An important part of regular maintenance is to fully depress the accelerator pedal as if you were trying for that last HP in a pass. At full throttle on the pedal, someone should still be able to move the throttles at the carburetors. They shouldn’t be at the stops. Stressing the linkage will still cause the updated accelerator cushion to fail.

I disagree. One of the most common ways for people to leave horsepower on the table is to have their accelerator linkage not properly adjusted so that it doesn't open all of the way at wide open throttle. In a perfect world, when the accelerator is fully depressed to the floor, the carbs / MFI will be completely open and giving 100% of the horsepower of the engine. You can adjust them back so that they are not fully open, but I wouldn't sacrifice power just for the sake of protecting the linkage.

-Wayne

Sunday911T · 09-19-2006, 05:50 PM

Scott,

Great story. Wish I thought of something as simple and effective before ordering the flatbed to take me home this past weekend. The rubber coupler failed just as I rolled into our library parking lot (btw, a library is a fairly comfortable place to break down).

A couple of questions for you: are the Improved Throttle Link (#911-423-081-02-M260) and the Accelerator Rod Boot (#911-423-593-01-M208) the only parts that I would need to order for the repair? Also, the smaller end of the boot in your picture looks a little bigger to fit the new throttle link -- is it bigger or is it the same size as the old boot?

Thanks in advance for your help.

Keith

hmd · 09-19-2006, 06:06 PM

I had similar thing happened to me twice, once was the rubber coupler and the other time was the linkage at the manifold broke off its base.

Both times were temporary fixed by cable ties, the moral of the story is to have lots of cable ties in you trunk.

After the second time it happened I put in an accelarator pedal stop to prevent overstressing the linkage BUT STILL making sure I had WOT when the pedal is fully depressed.

W Scott Shores · 09-22-2006, 09:03 AM

Quote:

Originally posted by Sunday911T
Scott,

Great story. Wish I thought of something as simple and effective before ordering the flatbed to take me home this past weekend. The rubber coupler failed just as I rolled into our library parking lot (btw, a library is a fairly comfortable place to break down).

A couple of questions for you: are the Improved Throttle Link (#911-423-081-02-M260) and the Accelerator Rod Boot (#911-423-593-01-M208) the only parts that I would need to order for the repair? Also, the smaller end of the boot in your picture looks a little bigger to fit the new throttle link -- is it bigger or is it the same size as the old boot?

Thanks in advance for your help.

Keith

Hi Keith,
Yes, those are the two parts I ordered to do the repair after I got home from the road trip. The boot is a little different size, but it seems to fit fine.

The only reason I didn't use a flatbed is because I didn't know where I was!

k9handler · 09-22-2006, 10:36 AM

This was the case with me going into Cali from AZ...pulling away from the agriculture check and pop no power! My fix was a few of the red agriculture seals they use to secure the back of the tractor trailers. This linkage made the trip to Kaiserslautern Germany from the port in Bremen...so keep some zip ties in the glovebox as they will work in an emergency.

lazydays · 10-23-2006, 05:21 AM

Wow, I am hunting for the parts I need to repair my broken linkage, I am so jealous that I didn't have a clue how to remedy my breakdown myself. I relied on the AA (Automobile Association) Ireland and sat so upset in the yellow truck !! Sometimes it pays to be male with your lateral thinking!!! Sorry girls. By the way is the linkage break why my black lever has stopped working I thought I could have limped her on with this but no way.

WHCJr72S · 10-23-2006, 08:25 PM

Lazydays:
Yes the broken link is why your black lever is not working. You will need to jack up the car and disconect the throttle rod from the peddle connection to replace the link.

lazydays · 10-24-2006, 01:23 AM

So far a temporary repair of a piece of wire is reconnecting the linkage . My black lever has not been reconnected,I would love a diagram to show my saviour where to reconnect the lever.
Meanwhile I have to wait until he tells me which parts to order from Pelican.
Thanks for the information.
Mary

Zeke · 10-24-2006, 07:10 AM

Quote:

Originally posted by Wayne at Pelican Parts
I disagree. One of the most common ways for people to leave horsepower on the table is to have their accelerator linkage not properly adjusted so that it doesn't open all of the way at wide open throttle. In a perfect world, when the accelerator is fully depressed to the floor, the carbs / MFI will be completely open and giving 100% of the horsepower of the engine. You can adjust them back so that they are not fully open, but I wouldn't sacrifice power just for the sake of protecting the linkage.

-Wayne

I didn't see this thread when it was new. I have always postulated that a very tiny angle of the butterflies still gives as much opening as it's going to. Butterflies don't need to open to perfectly vertical, IMHO. Just short of verical might cause a slight difference in the turbulance, but so much happens to the air flow from top of velosity stack to valve seat, the percentage of opening would be all I would be concerned with. If the butterfly is tipped so that the edges are still in line with the crossshaft as viewed from above, I can't see any significant air flow interruption.

Only if racers had gone to the extreme effort to mill down the butterfly thickness and reshape the cross shaft to a more condusive shape, would I believe that there would be a difference between 90* vertical and 88*

This would be my same opinion with regard to single butterfly systems.

BTW, my car, the Ragamuffin, came to me with the linkage wired together with a coat hanger. When did the new part become OEM? I'm sure my '88 has it, but I haven't spent that much time on the dark side of the car yet.

David E. Clark · 10-24-2006, 08:13 AM

Quote:

Originally posted by Grady Clay
An important part of regular maintenance is to fully depress the accelerator pedal as if you were trying for that last HP in a pass. At full throttle on the pedal, someone should still be able to move the throttles at the carburetors. They shouldn’t be at the stops. Stressing the linkage will still cause the updated accelerator cushion to fail.

Originally posted by Wayne at Pelican Parts
I disagree. One of the most common ways for people to leave horsepower on the table is to have their accelerator linkage not properly adjusted so that it doesn't open all of the way at wide open throttle. In a perfect world, when the accelerator is fully depressed to the floor, the carbs / MFI will be completely open and giving 100% of the horsepower of the engine. You can adjust them back so that they are not fully open, but I wouldn't sacrifice power just for the sake of protecting the linkage.

How about calling this heavyweight battle a draw! Here's the advice that's given most often to the drag racers who are looking for every last pony: Basic Carburetor and Fuel System Maintenance and Tuning Tips

"Maximum performance cannot be achieved unless the carburetor is wide open when the throttle is pushed to the floor. Consequently, throttle opening should be checked regularly, immediately following any major changes in the engine compartment. Maximum air flow cannot be achieved if the carburetor does not reach wide open, or if it’s pulled past wide open. It may be necessary to install a stop to prevent the carburetor form being opened too far and to prevent damage to the linkage. Linkage should operated smoothly with no binding and should be free of obstructions which may cause the carburetor to stick open. An auxiliary return spring MUST always be installed to insure that the throttle positively closes."