TheSamba.com :: View topic - 74' Bug doing "Bucking Bronco" when taking off in

Tue Feb 18, 2014 12:18 am

Hello to All,

I just bought a 74' standard Bug (1600cc) a few weeks ago and noticed that, often, she wants to "buck" then "pause" (engine goes silent!) when I try initial take off in first gear. I'm giving it gas, sometimes real quick snaps at the gas pedal before letting up on clutch....which I let up slowly to feel sweet spot. When engine goes to that quiet phase, I immediately press down on the clutch so she doesn't die. Then I let up slowly on clutch while giving it some gas, and then I can take off smoothly....sometimes.... I thought I'd have it figured out by now, but it seems to happen often- especially when I just started her up for the first time for the day. I do the warmitup (John Muir style) also. And installed a new air filter, thinking maybe the carb was starving for air....Can anyone point me in the right direction?
Thank you if you've read this far!!!

Tue Feb 18, 2014 12:28 am

Mine used to do that when I had a 009 distributor on it. Do you have a vacuum advance?

Tue Feb 18, 2014 12:41 am

Just took a look at the engine--it's a 009 distributer-with no vacuum advance

Tue Feb 18, 2014 12:42 am

Thanks for the response btw!

Tue Feb 18, 2014 6:28 am

I'm less knowledgeable than most of the guys who post on this forum, so take my thoughts with a pound of salt.

But, from what I understand, the mechanical advance distributors don't advance timing until you've already started to accelerate, whereas the vacuum gives a little turn to it the second you step on the peddle, and then the mechanical can catch up.

People liked those 009s because they were cheap and the timing ratio in them was such that you got a little more power over-all.

AirCooled.net rebuilt new Bosch "SVDA" distributors that had the best of both worlds. They can no longer build those because the supply went dry with the end of production for the Mexi-Bug, but Pertronix copied those, and AirCooled.net sells them - with electronic ignition already installed.

I bought one, but haven't gotten to the point in my project of installing it and trying it yet.

There may be other problems with your car, but this is just a shot in the dark for a novice.

Enjoy your car! I've been in love with mine since I was 11 years old.

Tue Feb 18, 2014 10:06 am

shadmock,
check your slack in clutch cable and a tube that hangs off the trans as well. I forgot what the tube is called but if its not adjusted properly it will buck.

Tue Feb 18, 2014 10:24 am

What carb are you running? Mine is a stock 1600 d/p with a 34-3 carb and it did similar and just ran poorly overall when I got it. I replaced the 009 that was on it with a Bosch SVDA (single vacuum duel advance) and it made all the difference in the world! It's a ton better now. Still a small weak engine but now it runs like it should. Not all carbs are compatible though.

Tue Feb 18, 2014 10:31 am

JBall8019 wrote: shadmock,
check your slack in clutch cable and a tube that hangs off the trans as well. I forgot what the tube is called but if its not adjusted properly it will buck.

Just to clarify to the OP, this is the cable that goes from the pedal to the transmission. You want about a 1/2 inch of play in the clutch pedal before you feel resistance, feel it with your hand and not your foot. If it doesn't have enough play. there is a wing nut on the end of the cable at the transaxle to adjust the tension, loosen it once at a time and check the pedal. It doesn't take much. I don't think that's the problem though, sounds like the classic 009 stumble, rev is through the roof and ride the clutch or it dies.

Tue Feb 18, 2014 3:06 pm

Bowden tube was the name!
http://www.vw-resource.com/bowden_tube.html

Since your description was "bucking bronco" , it reminded me of the adjustment I had to do on my Thing about two years ago.

Tue Feb 18, 2014 8:53 pm

Hey Everybody,

Thank you for the responses and help!

My carb is a Bocar 34-3 with the 009 distributer w/o vacuum advance. I looked into distributers online and saw the Mallory distributer and this:http://www.svda-distributor.com/
I read up on the differences between the 009 and the SVDA and gained some insight- I think I want to switch out that 009!!

About the Bowden tube--do you need to take the rear left tire off to locate it or is it visible by crawling under w/o being jacked up?

Thank you again guys!!! It feels good having a bug!!

-Sean

Tue Feb 18, 2014 9:04 pm

Oh--I also checked the play on my clutch pedal (w my hand!) and there is 1/2" of play...

Wed Feb 19, 2014 9:58 am

The clutch cable is on the driver side of the transaxle close the the engine. You can access it from under the car. With a 1/2 inch of play, if you don't have any other symptoms of a slipping clutch (burnt smell, reving high without acceleration) I don't think that's it. You need to change out the 009. A Bosch 034 (svda) would be great, it's what I run. But They stopped making them a few years ago. Try looking here on the classifieds for one. Expect to spend about $200. It's a super easy swap, but you will have to time it with a light when you're done.