rgr33n
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| posted on 18/10/07 at 08:29 PM |
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throttle cable
before i start, thanks to mark for bearing with me on saturday!
i snapped my throttle cable...
i have a cable kit which colin sent over to me (together with the "crimp on" type nipple for the carb end of the cable).
my car was the first type7R (now ZR) and so there are a few things here and there where current design details have probably moved on. i was using an
original sierra throttle cable with the stop spring on the carb bracket, but have now removed all that as part of fitting the universal cable kit i
have.
i got as far as fitting the cable to the carb (crimping the end onto the cable and pushing it over the "mushroom" shaped peg on the lever
on the carb) and fitting the cable to the bottom of the accelerator peddle. i took out the slack with the small adjuster on the engine side of the
pedal box and started her up...
the cable didn't retract, so the engine revs kept climing and i turned off the ignition. i can't quite work out why the spring on the
carb didn't pull the cable back and "retract" the peddle to the "off" position.
anyway, i'm not really a technically minded person and this is driving me mad. i need to get back on the road asap before the weather breaks!!!
not bothered about the cold - i just need to get out before it starts raining too much!
can anyone send me [or post a link to] a pic of their carb, including (or in addition to a pic of) the cable route please?
any help would be greatly appreciated!
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jos
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| posted on 18/10/07 at 08:58 PM |
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Heres mine
Hope it helps
 
Description
 
Description
.: Motorsport / motor racing circuit / track wall art Apex Traxs :.
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rgr33n
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| posted on 18/10/07 at 09:38 PM |
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thanks jos. you have the throttle stop spring arrangement which i had until lunchtime on sat.
i should take ands post a pic really - it will probably all make so much more sense then!!
bascially what i have now looks very similar, but without the spring on the black plastic wotsit where the cable goes through. the end of your cable
looks similar to how mine was, but mine is now a bare end, with a crimped nipple with attaches over the peg on the lever which operates the carb
rather than around it (as your appears to from the pics, and as mine used to be).
more pics from other cars would be greatly appreciated!
[Edited on 18/10/07 by rgr33n]
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DarrenW
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| posted on 18/10/07 at 09:42 PM |
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What engine / carb do you have?
My last carb (38DGAS) was cabled up very similar to Jos's pics. Single spring on the carb quadrant. Quite strong.
Is your pedal got free movement - ie not too tight?
Can you actuate the throttle from the carb end easily? When you do this does the cable move inside the outer nice and easy?
Have you tried getting someone to press pedal whilst you observe what is happening at the carb end (engine off)? Ie check that throttle butterfly is
returning to closed position?
Did you cut the outer cable? Could it be slightly distorted at the cut and be preventing the cable from returning to rest position?
When you say revs are rising, is this an instant 0 - 10K revs in 1 second type of rise or a slow increase? If slow could this be caused by the
butterfly being open indicating the cable adjustment is wrong.
It must be something simple if it was OK before. Assuming the inner runs in the outer OK it can only be a problem at either end (if nothing else has
changed).
When the revs are rising can you put pressure on the carb throttle shaft to get them to fall again
Maybe a pic of your set up may help for comparison.
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rgr33n
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| posted on 19/10/07 at 08:42 AM |
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i just typed a long reply, but forgot to log in - d'oh!!
engine is a 2 litre pinto out of a sierra, which i think was an 88/89 model. sorry, no idea what the carb is - but hopefully mark/colin will see this
and may be able to recall - although it was a few years ago now!
the pedal had complete free movement downwards (ie open throttle), but didnt; spring back. i would assume that meant it was not tight enough....
however, when i pushed down on the pedal (just a little - not too hard at all), the throttle jammed open and the revs started climbing - this happened
3 times and revs prob got no higher than about 3,500 before i killed the engine.
after all that, i managed to pull the cable out of the crimped nipple when i next adjusted the cable and starting the engine again
the carb operates fine with the lever - it's just when you introduce the cable that the problem occurs
the cable runs freely within the inner and outer. i've cut the outer, and checked the cut end before i put the cable in the car
a pic with definately help - i will try and get one later today. thanks for your help darren
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DarrenW
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| posted on 19/10/07 at 03:17 PM |
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It almost sounds to me like the pedal pivot bolts are a little to tight or the spring return on the carb isnt strong enough. After that it could maybe
the routing of the throttle cable (tight corner perhaps??).
With engine off have you tried pressing the throttle pedal and releasing to see if the movement is smooth and free? If the pedal was Ok before and all
you have done is change the cable then id suspect the cable.
There cant be much wrong with it.
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jos
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| posted on 19/10/07 at 06:27 PM |
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Try slackening off the nut and bolt that the accelerator pedal pivots on just a quarter or a half turn and see whether when you press the pedal the
spring is storng enough for the pedal to return to its normal resting position
.: Motorsport / motor racing circuit / track wall art Apex Traxs :.
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rgr33n
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| posted on 22/10/07 at 12:35 PM |
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unfortunately i was ill at the weekend, so didn't get the chance to get out there and take a more detailed look at the car!
i did check how tight the nut on the bolt at the bottom of the peddle was before fitting the other end of the cable (ie to make sure it moved freely),
but i didn't check the peddle pivot bolt itself
still haven't taken a pic! will try and do so tonight.
i "tested" my impreza next to a 450 chimera yesterday. the difference is similar to the difference between my impreza and my 7R/ZR. i have
to see how the mac1 compares to the chimp as soon as i get this cable sorted!!
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rgr33n
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| posted on 26/10/07 at 08:00 PM |
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finally got round to taking a few pics. i made sure i also took a pic showing the cable route so we can hopefully that out as a contributory factor.
i just tried the cable in the outer and it seems to run freely enough - i may just have pushed the pedal too far....anyway if anyone sees an obvious
mistake from the following pics (and believe me, i expect somebody will!), please let me know!
http://www.locostbuilders.co.uk/photos.php?action=showphoto&photo=4PICT0001.JPG
http://www.locostbuilders.co.uk/photos.php?action=showphoto&photo=6PICT0002.JPG
http://www.locostbuilders.co.uk/photos.php?action=showphoto&photo=2PICT0005.JPG
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jos
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| posted on 26/10/07 at 08:49 PM |
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I cant see a spring??
Is it just me??
.: Motorsport / motor racing circuit / track wall art Apex Traxs :.
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rgr33n
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| posted on 26/10/07 at 09:09 PM |
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mark told me to cut it off, so i did 
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jos
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| posted on 27/10/07 at 07:36 PM |
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You need to find a way of getting the pedal to return to its normal position - the spring is the normal way of doing this.
Some bke carbs actually run a push me pull you arrangement so that they dont need the spring. Twisting the throttle one way pulls the cable and
letting go or twisting it the other way pushes the cable
.: Motorsport / motor racing circuit / track wall art Apex Traxs :.
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rgr33n
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| posted on 27/10/07 at 09:41 PM |
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yes, i have a QA (quick action) throttle on my ts1 lambretta - works in exactly that way
when i spoke to mark about this, his view was tha the return spring on the carb was likely to be suitable to provide the "return to
neutral" position - am i expecting too much from this spring? - ie if i manually twist the lever to rev the engine, it will happily return to
idle speed as soon as i let go
[Edited on 27/10/07 by rgr33n]
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jos
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| posted on 28/10/07 at 08:18 AM |
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yup, it sounds as though the springs you've got at the mo are in need of some assistance
.: Motorsport / motor racing circuit / track wall art Apex Traxs :.
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rgr33n
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| posted on 22/2/08 at 10:38 PM |
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well, in between leaving my old job and starting a new one (a big deal for me as i had been with my old employer for over 13yrs!), i managed to make
it our to the garage and past the beer fridge last weekend.
turns out the cable was binding. too bl00dy simple for me to have worked out when i last looked at the car, but at least I now know what the problem
was.
i'm going to weld a different lever on the rod on the carb so the mushroom connector which works with the barrell nipple can be replaced with a
simple screw on nipple.
does anyone have pics on any similar fixes? (and i'm not talking about nipple piercings)
...i really should try and make it to a m1moc meet at some point!
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rgr33n
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| posted on 11/4/08 at 04:05 PM |
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...and after all that the company i went to went bust!
...which led to me having a spare afternoon today and so i have finally fixed the problem. as i will not be able to fit sierra cables in future, my
set-up is now ready for another universal cable next time i need a replacement
i cut the mushroom peg off the rod which operates the carb and drilled out the rivet. i then bolted a 90 degree bracket (cabinet making fitting taken
from a pile of spares in the shed) through the hole where the peg was. the cable runs through the other hole, with a solderless nipple on the end.
http://i22.photobucket.com/albums/b307/rg194/Mac1/DSC00450.jpg
http://i22.photobucket.com/albums/b307/rg194/Mac1/DSC00451.jpg
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