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Second spring on 1979 throttle


Chris Bracey
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Does anyone know why there are two springs on the 1979 spitfire 1500, each carb has a spring but there is also strong spring from the link to a bracket on the suspension turret. Is this a form of "pressure back" to inctrease economy. Its so stiff the strottle has a pressure point to overcome at the start of throttle travel. I think the spring is too strong.?

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I fitted an extra spring to my Vitesse carb operating arm because I found the existing set up too light for my heavy right foot but years later believe the side loading it gave has greatly accelerated the spindle wear on the rear carb😖

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I'm pretty sure all of my Triumphs have had a second spring. Certainly both Vitesses did (one an early rod-and-arm linkage, the other a cable) and the pedal is ridiculously light without it. I think the Dolomite 1500 had two return springs on the intermediate linkage between the cable and the throttle shaft, as well as the one on each carb.

In part, I think it was done as a safety measure. Springs can break or fall off. If you only have one throttle return spring, and it breaks, then your throttle sticks open. If you have a second return spring then losing one of them only makes the pedal very light.

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Cables are not the best used , the way forward it to go to your local bikenshop and get some bike brake cables

These normally have a derin liner and a long cable will make two throttle cables 

You need to get the right fixed nipple and a solderless one to fit on the cut end 

Advantage is very cheap , better and you get two out  of one length.

Most spits have a twin spring , its designed to wear out the throttle spindles, the return spring needs to be on the pedal operation 

Rather than the carbs. Which have their own hair spring to return the throttle plates 

You need to keep tension in the cable so if the clip flies of you dont let the  nipple pop off the back of the organ pedal

Pete

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Swap the sting spring for a lighter version. I have used the STD carb springs, it helps the feel. 

Re cables, took a bit of searching but I found polished inner bike cables and PTFE lined outer. Used with solder less nipples it makes an ultra smooth cable, much much better than off the shelf items.

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6 hours ago, Pete Lewis said:

You need to keep tension in the cable so if the clip flies of you dont let the  nipple pop off the back of the organ pedal

Pete

Used to do that in Minis when I fitted new accelerator cables; they always jumped off the pedal and left me with no power, usually when needed!

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On 13/05/2019 at 08:10, NonMember said:

I'm pretty sure all of my Triumphs have had a second spring. Certainly both Vitesses did (one an early rod-and-arm linkage, the other a cable) and the pedal is ridiculously light without it. I think the Dolomite 1500 had two return springs on the intermediate linkage between the cable and the throttle shaft, as well as the one on each carb.

In part, I think it was done as a safety measure. Springs can break or fall off. If you only have one throttle return spring, and it breaks, then your throttle sticks open. If you have a second return spring then losing one of them only makes the pedal very light.

 

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Just now, Chris Bracey said:

 

Hi. I looked at leatherhead. It seems a fit on the 1979 although i know the car was built in 1978. I will stretch the spring or heat it to soften the tension. Right now its too tight and needs a reaĺy hard puch to get it started. I like a light throttle so mighttry with it off for a while. 

 

 

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Springs dont cause sticktion  your problem is more likley to be a cable problem

Worn outers and snagged inners need a high load to overcome initial movements   removing or  lightening the spring load just allows a poor cable to work a bit better...for a while

The double  spring arrangement was used for a good few years on twin Su spits .

Pete

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12 hours ago, Chris Bracey said:

Right now its too tight and needs a reaĺy hard puch to get it started. I like a light throttle so mighttry with it off for a while. 

 

 

I had that on my Mk3 GT6 way back, and it was worn bushes in the linkage mechanism, not the springs or cables. It used to be hard to push down, then suddenly it would surge forward and make the car jump. Check to see if yours has any movement that it shouldn't.

 

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