Getting full throttle range

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thejinx

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I seem to have more left in the throttle when the peddle is flat to the floor. If I pull the cable through anymore the engine isn't idling properly. To fast. Can I get the throttle cable right and then turn down the idle screw to slow the engine without messing the engine
 
I assume single carb? Adjust the cable so it takes enough slack out to get full throttle but make sure it doesn’t move the throttle arm off the stop.

Have someone Slowly press the throttle down while your at the back so you can see how much movement it’s getting.
 
On mine (1970 RHD), there was so much slop in the pedal and linkages that a lot of the pedal travel was lost by the time the motion reached the carb.
Worst was where the cross-shaft (through the chassis leg) rotates, just in front of the right-hand front wheel.
The hole was oval, so the shaft was moving backwards and forwards initially, rather than rotating and pulling the accelerator cable to the carb.
Also, the V-shaped bracket under the floor, that coverts the up/down pedal movement to push-pull at the cross-shaft, was very sloppy.
And where all the rods connect to crank-arms the holes were worn, wasting more motion.

VW design was to use bent connecting rods, retained with cross-drilled split-pins, but no bushing. So after nearly 50 years they get tired.

From pedal up to pedal down would only open the throttle half way (single Solex) no matter what I did with the cable.

Butty sells kits for updating all of the linkages, but the pedal-to-v-shaped crank, and v-shaped crank to cross-shaft, you could easily DIY refresh with a couple of oilite bushes, rose-joints and threaded rod. I chose DIY from pedal to cross-shaft, but the cross-shaft kit I got from Butty. His kits are simply lovely.

Either way, I would recommend considering having some adjustable geometry in there, so you can control how much pull you get at the carb linkage when you go from pedal-up to pedal-buried-in-the-carpet.
 
Maybe have a look under the bus while the pedal is being pushed to see where the worst of the slack is.
Hold the crank arm that actually pulls the throttle cable (inboard of the chassis member) to see how much pedal you need before it moves, and work your way through the rods and pins and cranks back to the pedal.
It might be you can fix it "enough" in just the linkages from the pedal to the cross-shaft that you already have the parts for.

But when I wrote that my cross-shaft outer hole was oval, I mean it had almost 10mm travel between frontmost and backmost position in what should be only a rotary movement.
So a very large part of my pedal travel just pushed the cross-shaft backwards in the oval hole before it began to rotate and pull the throttle cable.

I would say if you have more than a couple of mm side-to-side in the cross-shaft, or if you are feeling flush, get the Butty kit.
 
Looks like someone has had a go at repairing that before.

You would need to grind all that back flat to fit Buttys bearing carrier.

Or something like this, with a Buttys cross-shaft, might do the job instead ?
https://www.bearingboys.co.uk/Metri.../OBF101310-Flanged-Oilite-Bearing-Bush-6139-p

I'm not certain of the measurements, but you could check the new shaft and decide.
Make your hole big enough and round enough and push it in. The outer crank arm will stop it falling out.
You should be able to re-use your crank-arm but don't expect getting it off to be fun.

It's not really as good as the Butty dust-proofed roller-bearing, but it might be easier to fit and will stop the steel on steel grinding action that kills the original design.
 
Spoken to Buttys bits got new shaft and roller bearing kit on order. Next weekend will be fun. Keeping it easy. I can just cut the old shaft off grind back the bad welds. Red lead the area and fit Buttys bits kit.
 
starbiscuit said:
Worst was where the cross-shaft (through the chassis leg) rotates, just in front of the right-hand front wheel.
The hole was oval, so the shaft was moving backwards and forwards initially, rather than rotating and pulling the accelerator cable to the carb.
Also, the V-shaped bracket under the floor, that coverts the up/down pedal movement to push-pull at the cross-shaft, was very sloppy.
And where all the rods connect to crank-arms the holes were worn, wasting more motion.

We have the same problem. Butty doesn't do the cross-shaft for an early 69 RHD. At Butty's request Vinvan sent him pics and dimensions about 2 years ago but he has (to our knowledge) never produced one. I like the idea of the oilite bush insert though.
 
Half way through fitting Buttys Bits cross shaft and roller bearing kit. I thought as I was replacing the cross shaft I would cut the old one off. Under wheel arch grinder out, sorted. :D Where cross bar fits to accelerator cable no room for grinder and there was no way I was taking the brake master cylinder off. You can just fit a junior hacksaw in there. 15 mins and it was all off. Red oxide paint applied to places I grinded back so tomorrow fit the Buttys bits kit.

Do it early and we are off down The Gower. Sunday I will then sort my starter motor bush
 
Fitted the Buttys Bits kit today. What a difference. So much more power on the hills. There is a hill just by the house, last week I was coming up it in 2nd at less than 20 mph. Today. 3rd at over 30. Well happy.
 

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