rover3l123
Rover Fanatic
Originally from Llangollen area North Wales and relocated to the US in 1995 with the P5
Posts: 174
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Post by rover3l123 on May 15, 2010 19:13:30 GMT
Sorry for the dumb question but after refitting my carb today, I seem to have a problem with the accelerator linkage. In removing the carb a few weeks ago I disconnected the connection to the butterfly spindle rod and all I did today was to reconnect that. However, the accelerator pedal hardly moves. I disconnected the carb linkage again and still the accelerator pedal hardly moves. I don't see what I could have done wrong?
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Post by Phil Nottingham on May 15, 2010 20:21:36 GMT
Make sure the acceleratorpedal is fully up inside the car when the throttle on the carb is fully closed - the lever arm on the carb can be easily positioned precisely in the correct place
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rover3l123
Rover Fanatic
Originally from Llangollen area North Wales and relocated to the US in 1995 with the P5
Posts: 174
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Post by rover3l123 on May 15, 2010 20:51:57 GMT
I confirmed the throttle pedal is all the way up and I assume the butterfly is closed as the return spring is attached to the spindle and I can hear a positive metal on metal when I manually move the throttle spindle and let it return.
I assume though that if the throttle connection at the carb is disconnected as it was before I refitted the carb and again now as I try to troubleshoot this, then the accelerator pedal should move all the way to the stop in the footwell. It only moves about half an inch and I can feel resistance so some part of the linkage must be binding somewhere.
I have tried using the disconnected linkage from at the carb to see if I can manually move the linkage and it seems to be stuck somewhere as the movement is marginal.
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Post by stantondavies on May 16, 2010 8:42:07 GMT
Are the linkage bearings breaking up and jamming the linkage? There's about seven in total.
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Post by Phil Nottingham on May 16, 2010 9:37:01 GMT
There is a bell crank under the manifold this may have siezed or turned the wrong way or it or links be fouling the heater hoses etc?
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rover3l123
Rover Fanatic
Originally from Llangollen area North Wales and relocated to the US in 1995 with the P5
Posts: 174
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Post by rover3l123 on May 16, 2010 18:00:53 GMT
Some of the bearings through which the throttle rods pass are worn, but I don't think this is the issue as it worked fine before I removed the carb for rebuild. After spending all morning on it I have come to the conclusion that it is maybe due to how I am setting the linkage at the carburetor. This is difficult to explain in words but here goes
With the linkage disconnected from the carb the throttle spindle is pulled by the spring on the other side of the carb so that it comes up against a stop. If I turn the spindle by hand it turns clockwise until it reaches another stop. In the first position I assume it the butterfly is fully horizontal and in the second position I assume the butterfly is fully vertical?
What I have been doing is connecting the throttle to spindle link via the clamp bolt when the butterfly is fully open. When I do this there is very little movement possible of the throttle spindle when I attempt to push the accelerator pedal.
I am doing this wrong, should the butterfly be set differently than fully horizontal when the clamp bolt is tightened?
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Post by stantondavies on May 16, 2010 22:18:10 GMT
Broadly speaking the butterfly should be closed with the accelerator pedal fully up and open when the accelerator is depressed. That's all I've ever done, others may have more finesse in adjusting the linkage.
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rover3l123
Rover Fanatic
Originally from Llangollen area North Wales and relocated to the US in 1995 with the P5
Posts: 174
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Post by rover3l123 on May 19, 2010 10:23:57 GMT
Thanks for the clarification.
So starting with the butterfly closed (the return spring on the carburetor pulls it closed) and with the accelerator in the fully up position, I connected the throttle linkage at the spindle on the carburetor. With this arrangement the accelerator pedal is restricted in movement and the spindle only turns about a quarter of the way that it should. By disconnecting the throttle adjustment rod, to isolate the problem, the accelerator now moves freely. Then I checked with a mirror under the inlet manifold to check that the various parts of the linkage are free to move and not caught in the heater hose. All seems clear but the movement of this part of the assembly feels restricted. The rods with the ball joints seem to move and so I am thinking it is perhaps the shaft that runs parallel with the bulk head is not moving freely.
I did look at the bell crank under the manifold as Phil advised but I don't see how it could be in the wrong position as the connection from it via the rod to the throttle spindle wouldn't reach, or am I missing something here in my understanding?
All of this is very strange because all I did originally is to disconnect the linkage at the carburetor so that I could remove the carburetor for rebuild.
Can someone confirm the extent of movement of the carburetor spindle from closed to full open throttle?
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rcoups
Rover Fanatic
Posts: 148
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Post by rcoups on May 19, 2010 17:17:12 GMT
Where can youi get the throttle linkage bearings from?
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Post by stantondavies on May 19, 2010 21:37:19 GMT
JRW has some, £7.50 each I think - by seven + VAT & carriage it turns out expensive. I'm running without any, and have done for some time.
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Post by Ken Nelson on May 25, 2010 20:19:45 GMT
Greetings from across the Lake, as opposed to across the Pond. Where in Wisconsin are you located? I live in Grand Rapids, MI. I'm not sure from your description if this applies, but I had a problem with my accelerator pedal being restricted from going down also. After quite a bit of hunting around, I realized it was a misadjustment of the overdrive inhibitor switch. This works on a cam off the throttle linkage to push in a pin on the switch preventing o/d from activating at low throttle speeds on the manual shift car. If yours is a manual I would check this under the intake manifold (it's really in a bad spot to get at). If not, it probably doesn't apply. I ended up removing the switch completely because I discovered it had stopped working anyway. Let me know if this helps at all. Ken
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rover3l123
Rover Fanatic
Originally from Llangollen area North Wales and relocated to the US in 1995 with the P5
Posts: 174
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Post by rover3l123 on May 25, 2010 22:12:51 GMT
Hi Ken
I am in the Sheboygan area midway between Milwaukee and Greenbay
Thanks for the suggestion, I have the air filter assembly off right now and so I will get my head under the hood (bonnet)) and see if this might be the issue. Mine is a manual with overdrive.
In my other post "carburetor tuning" I have posted some photographs of parts of the linkage
What year and model is your P5 and how did you come by it?
David
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Post by Ken Nelson on May 25, 2010 22:52:56 GMT
Hi David, my Rover is a 1966 3-litre with 4-sp o/d tranny. I had a friend in our local MGA car club who ran this car into the ground before me and I'm almost done restoring it. I will bet that your linkage problem is exactly what I had. The o/d has an inhibitor switch tied in with the throttle linkage. There is a cam that swivels and activates a spring loaded pin at idle speed to shut the o/d off. When accelerating this swivels down and allows the pin to pop out and the switch connects the two wires to it. If not set correctly, the linkage will allow the cam to swivel too far back and the pin will pop off the cam entirely and not let the throttle/accelerator linkage be pressed down again. Your picture of linkage is great, except that this cam and switch sits all the way under the manifold and back against the firewall. You almost have to work with it by feel. Try to use a mirror to look at it. If you want you can send me an email about it also. My address is listed with my name. BTW, I'll be at Lake Delavan in WI in July for our MGA national meet. Let me know what you find; I'm quite curious if it isn't the problem. Ken
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Post by Phil Nottingham on May 25, 2010 22:56:57 GMT
I would say you have identified the problem - Ken - a rare manual/od, they are not common in the UK
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rover3l123
Rover Fanatic
Originally from Llangollen area North Wales and relocated to the US in 1995 with the P5
Posts: 174
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Post by rover3l123 on May 26, 2010 3:13:39 GMT
Thanks Ken for the description of the potential problem. I will look at this tomorrow evening after I finish work and I will report back with my findings.
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rover3l123
Rover Fanatic
Originally from Llangollen area North Wales and relocated to the US in 1995 with the P5
Posts: 174
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Post by rover3l123 on May 29, 2010 17:14:24 GMT
Problem solved - Ken Nelson was spot on with his diagnosis. The linkage was binding on the overdrive cam switch. I was able to adjust this and the linkage now works as intended. Ken you were correct, this is almost impossible to get at.
Thanks Ken and to everyone else that provided suggestions.
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Post by richierover on Nov 29, 2022 0:10:04 GMT
Greetings from across the Lake, as opposed to across the Pond. Where in Wisconsin are you located? I live in Grand Rapids, MI. I'm not sure from your description if this applies, but I had a problem with my accelerator pedal being restricted from going down also. After quite a bit of hunting around, I realized it was a misadjustment of the overdrive inhibitor switch. This works on a cam off the throttle linkage to push in a pin on the switch preventing o/d from activating at low throttle speeds on the manual shift car. If yours is a manual I would check this under the intake manifold (it's really in a bad spot to get at). If not, it probably doesn't apply. I ended up removing the switch completely because I discovered it had stopped working anyway. Let me know if this helps at all. Ken
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Post by richierover on Nov 29, 2022 0:13:59 GMT
Ken. Thank you for the information, our P5 does not have overdrive how ever it did have an over drive switch fitted which did stop the accelerator arm moving fully. Your information saved a lot of time 👍
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Post by Ken Nelson on Dec 1, 2022 23:21:07 GMT
Glad to hear it Rich. It gave me fits for a long time until I finally figured it out!
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Post by MK IA Norway Viking on Dec 1, 2022 23:27:02 GMT
Can it be that this "Overdrive Switch" actually is the kickdown mechanism ? I presume you have an MK I-series ?
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Post by Ken Nelson on Dec 2, 2022 14:01:37 GMT
My inhibitor switch on MkIIC coupe is not a kick down switch. I assume the same on a MkI?
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Post by MK IA Norway Viking on Dec 2, 2022 14:48:06 GMT
The MK I auto has a mechanical contraption to operate as kick-down. The MK I manual have a switch on the steering column operating a solenoid on the overdrive unit mounted aft of the gearbox.
The MK IIc manual has both a switch on the steering column (like the MK I) and a button on the gearshifter knob. I am not familiar (yet) with the layout of the accelerator linkage.
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Post by Phil Nottingham on Dec 2, 2022 15:22:35 GMT
The MK I auto has a mechanical contraption to operate as kick-down. The MK I manual have a switch on the steering column operating a solenoid on the overdrive unit mounted aft of the gearbox. The MK IIc manual has both a switch on the steering column (like the MK I) and a button on the gearshifter knob. I am not familiar (yet) with the layout of the accelerator linkage. The manual/overdrive and auto box setup are all different as to Mk1/Mk1a, Mk2 and Mk3 (P5Bs are different again) The button on the floor change gear lever on manual and manual/overdrive cars is the reverse gear gate stop. Only Mk1/Mk1a had an overdrive kickdown operated by accelerator cam switches and an accel pedal switch. The auto Mk1/Mk1a and Mk2 had a cable operated kickdown + a gear hold delay which was dash cable operated on Mk1s and solenoid + cable on Mk2. Mk3s had a different cable operated arrangement to do both kickdown and hold delay The Mk1s and Mk2s had a large throttle linkage inhibitor/reverse light slider switch on the bulkhead. Mk3s had a compact gearbox switch A study of the workshop manual is essential to appreciate what is there and how it is set up on the various models
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