TR3 Accelerator Movement

[Cswillett]

Hello

 

I was hoping someone may be able to help me, on the TR3 the accelerator pedal will sit flush with the rest of the pedals (Brake + Clutch) however if you touch it the pedal will drop about 5cm and from then on you get resistance and active throttle movement. I was hoping this may well be a case of just worn bushes.

 

If anyone has any ideas what else it could be please feel free to chip in.

 

Thanks

[Lebro]

Not likely to be bushes, the rod which starts at the pedal, then loops around the top of the brake & clutch then passes through the bulkhead (in a bush), and on the other side a lever is pushed onto the end of it. This lever should be pinned to the rod. sometimes the pin shears, & allows the lever to pivot on the rod - often it will not pivot far, & so will allow throttle to operate. There should be a return spring on this lever to pull it back to the bulkhead.

So, get someone to move the pedal up & down, & check to see if the lever is moving with it. If all that is OK, then you need to check further along the system - watch the horizontal rod under the carbs, does it move with the pedal, then watch the pivot at the front end of that rod - is it moving & pushing the short vertical rod ok, is it too wobbly on it's pivot ?.

Finally check that the butterfly spindles are following the final lever at the top of the short vertical rod.

 

Something amongst this lot will be the problem, or maybe a combination of all.

 

Bob.

Edited March 20, 2017 by Lebro

[BlueTR3A-5EKT]

...and that is why I converted to cable operation in 1972

 

Peter W

[Fireman049]

Hi Peter ~

 

I've always been an advocate of cable throttle operation.

Any chance of some photo's? Did you fabricate the system yourself or is it available commercially?

 

Tom.

[tim hunt]

It looks like the 4A accelerator system is the same as on the earlier cars and reading this thread reminded me of an incident way back. Father and I were on our way to a Club Triumph meeting at the Jolly Farmers in Enfield in what was then his 4A when we suddenly lost the accelerator just as we came into Barnet. As luck would have it we were able to coast to a halt on the forecourt of a garage (now an STS tyre fitters) and a mechanic was still working there, although it must have been around 7.00pm. He quickly found that the pin meant to secure the lever assembly to the accelerator shaft had dropped out. A replacement pin was promptly fitted and this is still doing its job over 42 years later. The guy didn't even want to charge us - those were the days! The design of the assembly does provide lots of potential for lost motion and slop but I find that by having all throttle rod joints correctly adjusted and all bearing surfaces regularly lubricated the system works fine although I agree with Peter that a cable would be much simpler.

 

Tim

[Cswillett]

Many thanks for all the helpful replies. Will take a look to see if it is the pin, will make things very simple if that is the problem!

[EdwinTiben]

Had the same problem, there was Some play in several joints, which, together gave inches play in the pedal. I drilled out the holes of the pin, to have a slightly larger pin

[TR24178]

Cable operation is not as good or original, its a very sound shaft and rod system which is very strong if you do a little mod, the weak points are pins that hold it all together, I replaced them with roll pins and also fitted extra roll pins at 90 degrees on all the joints, no slack anywhere now and much stranger that cables, we always fit 2 cables on rally cars (not sidescreen TRs) because of breakage of the cable, I am restoring a 1959 Fairthorpe Electron Minor and thats got Triumph Herald Coupe cable operated throttle, its not that positive!!

[TR 2100]

I went to considerable lengths to AVOID cable linkage when

fitting my Webers.

 

On a standard setup - to me - no argument.

Must be based on the standard rod linkage.

(But - have to say - never actually tried cable!!)

 

There are upgraded rods available in the US that improve

the system - I got mine through eBay although they are not

always listed.

 

AlanR

[mike ellis]

Not likely to be bushes, the rod which starts at the pedal, then loops around the top of the brake & clutch then passes through the bulkhead (in a bush), and on the other side a lever is pushed onto the end of it. This lever should be pinned to the rod. sometimes the pin shears, & allows the lever to pivot on the rod - often it will not pivot far, & so will allow throttle to operate.

 

 

 

The lever was originally pinned with a Mills pin (i.e. tapered) fitted at the worst angle for removal. Best to drill out and replace with a suitable size roll pin.

[BlueTR3A-5EKT]

Photos of how I did it - right or wrong

'P' clip on pedal is positioned by wire locking wraps

Note spare cable tucked up on bulkhead

 

 

 

 

 

Cheers

Peter W

Edited March 25, 2017 by BlueTR3A-5EKT