AidanT Posted January 4, 2016 Report Share Posted January 4, 2016 Hi All For ages now my GT6 has suffered from the accelerator pedal vibrating on deceleration (Foot not On Pedal), whether braking or not. I have changed the bushes and Spring but to no avail Note this is the lever type and not a cable assembly Anyone come across this before and found a solution? Thanks Aidan Link to comment Share on other sites More sharing options...
Clive Posted January 4, 2016 Report Share Posted January 4, 2016 I suspect it is teh throttle discs opening and closing a tad (this was "solved" on late SU's by using a poppet valve, a whole other problem!) And of course, the lever for the accelerator is rather long making it sensitive. I have changed any levr/rod accelerator to cable operation to gain super smoothness and generally rather nicer to use. I doubt there is anything wrong with yours at all. Link to comment Share on other sites More sharing options...
AidanT Posted January 4, 2016 Author Report Share Posted January 4, 2016 Thanks Clive Its good to know the reason! Would a simpler solution be to fit a spring, in the foot well, that would hold the pedal under light tension even when not being depressed? Aidan Link to comment Share on other sites More sharing options...
Clive Posted January 4, 2016 Report Share Posted January 4, 2016 I thought there was a spring on the long arm? but a spring, or 2, would certainly help. Link to comment Share on other sites More sharing options...
AidanT Posted January 4, 2016 Author Report Share Posted January 4, 2016 Hi there's only the return spring inside the engine bay. I will have a go at fitting one in the foot well then, I have a few springs that might just do the job. Thanks for the advice Aidan Link to comment Share on other sites More sharing options...
Pete Lewis Posted January 4, 2016 Report Share Posted January 4, 2016 yes im sure rod throttles had a spring from the arm to the pedal box certainly there was one on my Vit6 rod set up just looked at gt6 and they dont show the same but adding one cant be hard to come up with a set up too light is often a vibro problem under the foot Pete Link to comment Share on other sites More sharing options...
AidanT Posted January 4, 2016 Author Report Share Posted January 4, 2016 I will put something together this month If it works I will add a picture to this thread Aidan Link to comment Share on other sites More sharing options...
Pete Lewis Posted January 5, 2016 Report Share Posted January 5, 2016 leggo or meccano ??? Ha Pete Link to comment Share on other sites More sharing options...
AidanT Posted January 5, 2016 Author Report Share Posted January 5, 2016 Definitely Leggo - The Big Block junior stuff!! Aidan Link to comment Share on other sites More sharing options...
JohnD Posted January 6, 2016 Report Share Posted January 6, 2016 This is vertical vibration? Not side to side? And this might be harmonic vibration. A small impulse from the closed throttles matches the period of vibration of the pedal. If you change the latter, the it might go away. A spring would help, but better a weight added to the pedal. Can be done temporarily as a test, say a large bolt or two clamping a strip of metal to the lever behind the pedal itself. As far from the pivot as possible. John Link to comment Share on other sites More sharing options...
AidanT Posted January 6, 2016 Author Report Share Posted January 6, 2016 Definitely Vertical, could well be down to harmonics, Its quite intermittent as well. I am not sure what impact weighting the pedal would have, the throttle return spring does not put a massive load on the assembly, its quite well balanced, but I will have a go anyway and see what results I get Thx Adian Link to comment Share on other sites More sharing options...
JohnD Posted January 6, 2016 Report Share Posted January 6, 2016 A weight would change the base harmonic of the lever system - like a pendulum. That has a great big weight at the bottom, and often small weights on the rod, that can be moved up or down to regulate the clock, because that small change will move the centre of gravity, and so the period of the pendulum. So you would not need a very large weight. Just a big bolt or two, as I suggested. Same applies to valve springs, but you can't add weight there. so double springs are used. This could work for you to, but the second spring should be much stiffer or shorter than the first. Then, the first harmonic is the multiple of the two springs base frequency. Just adding a similar spring will only make it harder work for your foot. John Link to comment Share on other sites More sharing options...
AidanT Posted January 6, 2016 Author Report Share Posted January 6, 2016 Thanks John I will try the various springs that I have around the place. and see what happens. I don't want to make the pedal to hard though so will not be using anything like a brake or clutch Return spring (PN:14438) they I would assume would be too hard - Going on Pete's comment Something like the Vit6 set up - unfortunately they are no longer available. Any ideas on a suitable spring would be appriciated Aidan Link to comment Share on other sites More sharing options...
JohnD Posted January 6, 2016 Report Share Posted January 6, 2016 Halfords do a boxed selection set (Mmmmmmmmmm! Scrummy!) http://www.ebay.co.uk/itm/like/191522732742?adgroupid=13585920426&hlpht=true&hlpv=2&rlsatarget=aud-133395220626%3Apla-131843260866&adtype=pla&ff3=1&lpid=122&poi=&ul_noapp=true&limghlpsr=true&ff19=0&googleloc=1006854&device=c&chn=ps&campaignid=207297426&crdt=0&ff12=67&ff11=ICEP3.0.0-L&ff14=122&viphx=1&ops=true&ff13=80 But link the new one in parallel, not series. Old spring stiffness = k1 New spring stiffness = k2 EG 2+4=6 In series New stiffness = k1 + k2 In parallel new stiffness is found by 1/newk = 1/k1 + 1/k2. EG 1/2 + 1/4= 1/0.75 newk=1.3 LESS total stiffness, but a much higher harmonic. John Link to comment Share on other sites More sharing options...
Clive Posted January 6, 2016 Report Share Posted January 6, 2016 Try a carb return spring? They are quite soft, but easy to use and you can pre-tension them or whatever. I have found them very useful. Link to comment Share on other sites More sharing options...
Colin Lindsay Posted January 23, 2016 Report Share Posted January 23, 2016 Hi there's only the return spring inside the engine bay. Aidan There should be a long spring from the arm to the front outrigger of the chassis.... possibly two, one long and one short. If yours is missing or lost tension this may explain why the pedal rocks about. Link to comment Share on other sites More sharing options...
AidanT Posted January 23, 2016 Author Report Share Posted January 23, 2016 I will be adding further to this as I am about to fit an additional internal return spring this weekend. I currently have a standard set up as per the diagram on the right below. My plan is to add a spring between the item No:4 plate and the pedal shaft. I think if I get the hole in the shaft in the right position the spring will be under tension even when the pedal is not being depressed I am going to adapt another return spring from the Vitesse 122392 Aidan Link to comment Share on other sites More sharing options...
Pete Lewis Posted January 23, 2016 Report Share Posted January 23, 2016 before you drill the pedal arm use a tyrap , even a small jubilee clip to fix the spring , then you can move it around first to get the required loading or you could end up with a lightweight pedal arm !!! Pete Link to comment Share on other sites More sharing options...
AidanT Posted January 26, 2016 Author Report Share Posted January 26, 2016 Update I managed to dismantle the current set up at the weekend, and found that there was a lot of movement between parts 14 and 1. It was only a small movement on the split pin but that equated to over an inch of free movement on the pedal. So I have added an additional split pin futher up @ 90 degrees to the original. I will now see if this resolved the issue. I can now see the original engineering concept of the assembly. The pedal shaft is held under tension supposedly by the double coil lock washer no:8 above, unfortunately the fulcrum bracket (no 4) is rather soft metal and so bends inward releasing the tension. I think I may have to fabricate a replacement for this at some point. The alternative is to heat treat it but i can't remember if that makes it harder or Softer! Anyway the additional spring awaits its use if the rattle persists! Aidan Link to comment Share on other sites More sharing options...
AidanT Posted August 13, 2017 Author Report Share Posted August 13, 2017 Sorry to bring this alive again but the vibration has returned and for the same reason as stated above The additional split pin now does not hold the two parts solidly together Would it be better to take both pins out and replace them with spring tension pins of a suitable size? I am not sure if the original part a"dowel" would just have been a solid pin Would this be a long term solution? And if not what else could I do to hold parts 1 and 14 solidly together? They do need to come apart still so no welding Thanks Aidan Link to comment Share on other sites More sharing options...
Pete Lewis Posted August 13, 2017 Report Share Posted August 13, 2017 Assemble with some loctite before locking with pin should work pete Link to comment Share on other sites More sharing options...
AidanT Posted August 13, 2017 Author Report Share Posted August 13, 2017 Hi Pete which one? Aidan Link to comment Share on other sites More sharing options...
Pete Lewis Posted August 13, 2017 Report Share Posted August 13, 2017 Any thread loc or hard setting sealer I swear by 574 its a multi gasket which sets hard once air is excluded I use it in far more applicatioms than its concept when its set you wont need a pin ha !, pete Link to comment Share on other sites More sharing options...
AidanT Posted August 13, 2017 Author Report Share Posted August 13, 2017 It may need to come apart again Pete Sods law says so! Aidan Link to comment Share on other sites More sharing options...
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