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Discussion Starter #1
My 1990 S4 has a jerky rod linkage for the throttle operation and it looks like a PITA to renew the ball joints.
My 1991 S4 auto has a much smoother cable operation. Is it possible to convert the rod linkage to a cable?
If so, what parts would I need (I'm guessing a cable, to start with..:D) ?
The cars are in different locations at the moment so I can't compare side by side.
 

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But Mad North-Northwest
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Renewing the ball joints isn't very hard, really. The painful job is replacing the bushing in the crank arm along the firewall.

In either case, it's probably an easier job than sourcing and installing the cable linkage. You'd probably need to pull all of the existing crap out anyway.
 

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Discussion Starter #3
You'd probably need to pull all of the existing crap out anyway.
Thats a good point. Although I could leave it in there so that the next owner has something to cuss me for...

OK, I'll have a go at replacing the ends and hope that the bushing doesn't need replacing.
 

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But Mad North-Northwest
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You can watch the pin mounted in the bushing in the crank end as someone actuates the throttle pedal. The pin should flex a little bit within the bushing, but if it flops around then the bushing is shot. It's a cheap part but you really need to pull the firewall crank to replace it.
 

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i will look at it, give it a try.. my little bush is ( bushing.. get your minds out of the gutter:):) ) is getting a little loose..my car is down for a week due to a re-design of the maita seat brackets..
 

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But Mad North-Northwest
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Yeah, mine was pretty shot when I got the car. Replacing it (and all the ball ends with grease-filled metal ones) improved things markedly. The other key is to get all the rods adjusted properly. It's still not as smooth as a cable actuated throttle, but good enough.

If the bushing is shot I suppose you could adjust the long front-back rod longer to take out some of the slop, but probably best to replace the bushing.
 

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I just replaced my bushing. Not really that difficult of a task, but like many other alfa projects it's a little time consuming. I had to have a machine shop press out the old and press in the new bushing. It took out about an 1" of slack but it appears as though I need to replace the little ball sockets as well, there's still about 1" of slack before the throttle advances. I noticed all 4 of the sockets have about an 1/8" of play in them.
 

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If you're replacing the ends, better to do it once and forever with these instead of the plastic bits:


Available at Centerline in the 'carburettor repair kits and mounts' section.
(yes, they will fit the L-jet linkage with no problem)
 

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Bumping this back up to see if anyone has done it. The title of the thread, converting from linkage to cable.

Not sure if Anglospider was talked out of it or not.

I found some pictures by John M of the throttle with cable (located at the air intake) when he installed cruise control but does anyone have system diagram?

DSCN5329.jpg

Is it that hard? What else is needed?

Thanks,

Vin
 

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Cable drive is the default on the Motronic system IIRC, so a schematic of that should get you where you want to be.
I have seen some '91s and all models after to have cable.

My '91, produced June 21, 1990, has the linkages. My shop manual also shows linkages.

If anyone has the schematic, that woudl be great.

Thanks in advance,

Vin
 

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Trained (ex)Professional, , 1953-2018 RIP
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If y'all can wait til this evening, I'll post the setup from the parts book.
 

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Discussion Starter #13
Not sure if Anglospider was talked out of it or not.
I haven't tried it and probably won't until I have replaced all the worn parts of the linkage to see what it is like then. Thats on the agenda for Easter. If its still c**p I will have another look at a cable conversion.
 

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papajam,

Thanks for the drawing.

I thought it would be easier than that.

Guess I'm heading out to the garage to grease those linkages as they are sticking!

Vin
 

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But Mad North-Northwest
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Vin,

Beyond the other tips in this thread, be sure to check the small crank arm directly beneath the throttle. The shaft can corrode and cause binding.

I found it easiest to pull off all the rods and actuate each of the devices in the system individually. This will let you identify any regions of play or binding.
 

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Discussion Starter #17
I replaced all 4 rod ends with new metal parts from Alfaholics. It was just as well I did them as the linkages almost fell apart by themselves when I took them off, they were really loose.

Its now really good - no play at all, so I won't need to try the cable conversion. Relief:D
 

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Discussion Starter #18
Update on this:

I subsequently replaced the bushing that Gubi and co. mentioned as there was a lot of flex in it. It wasn't too difficult to do - I used a vice and a couple of sockets to presss the old bush out.

Again, it made a big difference. So I am convinced that a throttle linkage in good condition is fine and there is no need for a cable conversion.
 

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AngloSpider,

Glad to hear you sorted it out.

I wish I had tried that first before converting to cable.

I like the cable but I dont think it is worth the trouble to convert. I was amazed at how many parts have to be changed. Not only the parts that the drawing Papajam has shown but there are a lot of hoses that needed to be changed including a different intake manifold!

Cheers,

Vin
 

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AngloSpider,

Glad to hear you sorted it out.

I wish I had tried that first before converting to cable.

I like the cable but I dont think it is worth the trouble to convert. I was amazed at how many parts have to be changed. Not only the parts that the drawing Papajam has shown but there are a lot of hoses that needed to be changed including a different intake manifold!

Cheers,

Vin

Hi Vin, long time lurker here. Thank you for your work across the BB'. I'm working with Larry @APE to source the conversion pieces for my 91' Spider with linkages. The colorado dust has ruined all of the swivelly pieces, so a full rebuild of all the linkage system is in order. I have some time right now in the dead of winter, and want to convert to cable drive.

Could you list out the pieces you needed? I know that a new throttle body is needed, the cable, assorted brackets - and a new pedal. How does the new pedal attach to the firewall? Larry is going to cut out and send me a piece of the firewall he's got for a cable-driven spider.
 
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