BOWDEN CABLE, BOWDEN CABLE,
09-14-2010, 01:57 PM
#1
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BOWDEN CABLE, BOWDEN CABLE,
I removed the slack in my bowden cable today and WOW! This was the most rewarding adjustment/repair that I have made to my 86.5 auto in the tewlve years I have owned it.
I was trying to eliminate the harsh gear changes and very sluggish performance. I worked on the vacuum system insuring that it was the not the cause. Very frustrating to spend all that time without any improvement. So before I spent any more $$ having the trans shop look at it I decided to try adjusting the bowden cables.
It hade been shifting way too soon, way too harsh, and only down shifting with the shift lever or kick down swicth.
I adjusted it tighter by just TWO TURNS and went for a test drive. WOW! New car!
Now it shifts smooth, holds first ,second and third gear longer allowing the engine to reach its proper power bands. I am sure this is the way a 928 should perform. Fast and agile.
Thank you Rennlisters for all the tech support. I would not own a 928 with out you.
I was trying to eliminate the harsh gear changes and very sluggish performance. I worked on the vacuum system insuring that it was the not the cause. Very frustrating to spend all that time without any improvement. So before I spent any more $$ having the trans shop look at it I decided to try adjusting the bowden cables.
It hade been shifting way too soon, way too harsh, and only down shifting with the shift lever or kick down swicth.
I adjusted it tighter by just TWO TURNS and went for a test drive. WOW! New car!
Now it shifts smooth, holds first ,second and third gear longer allowing the engine to reach its proper power bands. I am sure this is the way a 928 should perform. Fast and agile.
Thank you Rennlisters for all the tech support. I would not own a 928 with out you.
09-14-2010, 05:59 PM
#2
Racer
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Did yours have slack in it or did it look loose. My 86.5 has some harsh shift to it, the rubber boot looks like it has a curve to it but the cable feels tight. I have heard of some being adjusted 6 turn, seems like a lot. Jack
09-14-2010, 06:35 PM
#3
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Mine was VERY loose. It took 6 turns to get mine right. Workshop manual says 1mm of play. I could easily move the throttle plate 1/8" (over 3mm) or more with no Bowden cable movement previous to adjustment. After adjustment, it feels like a Porsche should... No more early or harsh shifting.
09-14-2010, 08:42 PM
#6
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As I understand it, the Bowden Cable transmits relative throttle position to the Auto trans. It is connected to the throttle quadrant at one end and inside the trans housing on the left side at the other. It is just a simple aircraft cable, nothing electrical.
Mike
Mike
09-14-2010, 09:03 PM
#7
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Be careful when adjusting. I just broke mine the other day and when I found out what it takes to replace it I ****. I am currently having a machine shop make a quick fix for it. I will post pictures when finished.
The cable broke where it goes into the threaded rod.
The cable broke where it goes into the threaded rod.
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09-14-2010, 09:10 PM
#8
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How did that happen? Adjusted too tight and stomped the pedal? I guess adjusting the cable, checking throw at the plate, then having a helper slowly push the pedal to the floor to check throw might be prudent.
09-14-2010, 10:33 PM
#11
From researching many posts there are three adjustments needed. Please correct or modify any of my interpretations as I do not claim to be an expert. It all comes from many posts that I tried to follow.
#1 Remove ball cap from bowden cable and tighten the pedal cable by turning counterclockwise the screw at the firewall until all slack is removed. This to me means you should be able to gently push on the pedal cable with a finger without moving the throttle body...say .5 inch.
#2 Tighten the throttle cable slowly while checking that the idle switch can still be heard with a click under the manifold. This means one turn at a time and then check by moving the linkage with your thumb to here the click and release until it will not return a click. Then release the throttle cable enough to release the click.
#3 Now attatch the bowden cable by gently pulling out the slack from the cable and turning the cup until it lines up to slip on smoothly.
Step #2 is important to release the idle switch.
One tip is to record how many turns in a note pad so you can return if needed.
Changing fluid and filter has to be done if you do not know service records, it made a big change on my tranny.
Again, please correct any misinterpretations in my post.
Ole
#1 Remove ball cap from bowden cable and tighten the pedal cable by turning counterclockwise the screw at the firewall until all slack is removed. This to me means you should be able to gently push on the pedal cable with a finger without moving the throttle body...say .5 inch.
#2 Tighten the throttle cable slowly while checking that the idle switch can still be heard with a click under the manifold. This means one turn at a time and then check by moving the linkage with your thumb to here the click and release until it will not return a click. Then release the throttle cable enough to release the click.
#3 Now attatch the bowden cable by gently pulling out the slack from the cable and turning the cup until it lines up to slip on smoothly.
Step #2 is important to release the idle switch.
One tip is to record how many turns in a note pad so you can return if needed.
Changing fluid and filter has to be done if you do not know service records, it made a big change on my tranny.
Again, please correct any misinterpretations in my post.
Ole
09-14-2010, 11:22 PM
#12
Under the Lift
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Ole:
That's good!
I often find gobs of useless slack in the "from (gas) pedal" section of the throttle cables. And when adjusting the "to throttle" half so you get it snug but still hear the idle switch click, what you are trying to do is take out all the slack you can but still have the throttle plate seating/closing against its stop, which should be at most just a few degrees beyond the idle switch. So, the idle switch and a few degrees more closure.
That's good!
I often find gobs of useless slack in the "from (gas) pedal" section of the throttle cables. And when adjusting the "to throttle" half so you get it snug but still hear the idle switch click, what you are trying to do is take out all the slack you can but still have the throttle plate seating/closing against its stop, which should be at most just a few degrees beyond the idle switch. So, the idle switch and a few degrees more closure.
09-14-2010, 11:41 PM
#13
Team Owner
and if you readjust the throttle cable portion on a S4 or newer auto,
you will change the bowden cable tension, so tightening the throttle cable in effect also loosens the bowden cable, you can get back some of the performance by simply reducing the tension on the throttle cable adjuster
you will change the bowden cable tension, so tightening the throttle cable in effect also loosens the bowden cable, you can get back some of the performance by simply reducing the tension on the throttle cable adjuster
09-15-2010, 12:00 AM
#14
I'm still not certain how to make sure the "go pedal" adjustment is right, it's hard to know what the correct amount of slack is....I wish I could go to a dealer and feel what the factory released these cars with on a brand new 928.
09-15-2010, 12:09 AM
#15
Ole:
That's good!
I often find gobs of useless slack in the "from (gas) pedal" section of the throttle cables. And when adjusting the "to throttle" half so you get it snug but still hear the idle switch click, what you are trying to do is take out all the slack you can but still have the throttle plate seating/closing against its stop, which should be at most just a few degrees beyond the idle switch. So, the idle switch and a few degrees more closure.
That's good!
I often find gobs of useless slack in the "from (gas) pedal" section of the throttle cables. And when adjusting the "to throttle" half so you get it snug but still hear the idle switch click, what you are trying to do is take out all the slack you can but still have the throttle plate seating/closing against its stop, which should be at most just a few degrees beyond the idle switch. So, the idle switch and a few degrees more closure.
I need to tighten to the point that the throttle body is about to move?