60ft, wheely and wheelybars questions

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joosep
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60ft, wheely and wheelybars questions

Post by joosep » Tue Apr 25, 2017 10:54 am

I have some questions about my car.
I know its not regular beetle but maybe you can help me out.

I made my first passes with that combo and it made 1.5 60ft on cold concrit with no burnout. What do you think how far I can go with 60FT when the wether is 25c warmer and I can do some burnout when it pulled already little wheely on slippy concrit ? I`m asking because I can´t use wheelybars on this car (Try to make it back to streetlegal for a class somehow and wheelybars wouldn´t help)
Is there way to get it under 1.3 without wheelybars or it pulls nose up before I can make it? How far you have gone more since it pulled wheels little up ?

Second question is about how it pulls to left when front wheels don´t hold. How should I fight against it ? Turn some more to the left shock absorber? More spring somewhere? or different tyre pressure? It pulls always to the left and rises more the right side.

Diff is welded.

Engine locates like this: viewtopic.php?f=19&t=146216&start=60

Ol'fogasaurus
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Re: 60ft, wheely and wheelybars questions

Post by Ol'fogasaurus » Tue Apr 25, 2017 11:40 am

I haven't played with straight line racing for many years (more than 30 years now) and even at that not that much (the $$$$ problem) but from what you are saying plus looking at the URL: just how much weight is there on the front of the car?

Pulling to one side or the other could be from engine torque (not sure which direction of rotation you are playing with) as on a couple of my cars you sure could feel it wanting to pull in that direction then when you let off on the loud pedal it would snap back to straight ahead but that was with in-line 6 and V-8 front engine cars.

For what it is worth (and that probably isn't much).

Lee

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joosep
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Re: 60ft, wheely and wheelybars questions

Post by joosep » Wed Apr 26, 2017 9:54 am

There are between 150 to 200kg on front wheels I think.
I don´t stay on my line when I let the pedal off @ 190+ :( it goes to left. I hope it was because of the wind but it was problem on all my 5 passes I made on weekend.
In start it turns to left too somehow.

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Re: 60ft, wheely and wheelybars questions

Post by Ol'fogasaurus » Wed Apr 26, 2017 10:38 am

joosep, I looked at your video and I see what you are talking about.

Have you tuned your suspension; e.g., preload for example? With a V-8 in the rear things are way different than with a opposed four, in-line 4/6 just in weigh as well as torque. It looked like one side was burning a bit more than the other side (rotational torque?).

The V-8 bugs I remember seeing were all front engine or mid-engine conversions and they had a lot of problems with "racking" in the pan unless they were a tube frame with a VW body on them (this would have been in the early to mid-70s as I remember. After one ride one of my friends refused to get back in his).

In the race sequence there was the turn into the right lane at the end of the track. Was that deliberate as getting prepared for a turn into the return road back to the start line or was that a wicked reaction from instant "power off" at the end of the track. If it was from taking your foot off the "loud pedal" isn't a good reaction by your car and can cause a wreck of several sorts?

I am assuming you have a full cage and it is installed properly so the pan isn't racking. Did you add some support from the pan/cage to the rear torsion bar? What about to the frame head. A Kaffer/Truss bar on the rear mounts? All things that could cause something like this.

Good luck as it looks like a better than average start on this.

Edited for some clarifications


Ol'fogasaurus
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Re: 60ft, wheely and wheelybars questions

Post by Ol'fogasaurus » Thu Apr 27, 2017 11:38 am

That is reminiscent of starts back in the 50's and 60s before a lot about suspensions was learned :wink: .

With the engine mounted the way it is, is the engine torque now rotating towards the left or the right (standing in the rear looking forward)?

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joosep
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Re: 60ft, wheely and wheelybars questions

Post by joosep » Thu Apr 27, 2017 2:05 pm

Torque rises right side of the car and push down left side. In start I think that left rear wheel moves so much up that it looses some teaction because of the camber change and whem right one has better traction the wehicle goes to left. What can I do? More spring pressure or more schock?

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Re: 60ft, wheely and wheelybars questions

Post by Ol'fogasaurus » Thu Apr 27, 2017 3:08 pm

joosep I haven't been involved with drag racing for a long time and I am sure things have changed a lot since then (because of all the new high tech stuff coming out in the early 90s that I got priced out of racing [plus a wife that did not have a clue other then money issues]). Also you are playing with a rear engine, short wheel base car which I don't have that kind of track experience with. There were guys running short wheel base cars (besides the "gassers") but I don't ever remember them talking to the rest of us much.

Back when I was playing around with this the battery had just been moved to the rear of light/right side. I had forgotten about cross the car torque transfer but I seem to remember about the same time there was work on both the shocks and the springs. If you can afford it try (are you running coil-overs??) a bit stiffer spring on one side to start with to see if there is any kind of a change.

We had front shocks (dampeners) that held the front end up longer allowing for the weight transfer to the rear to remain a bit longer but that may be old technology now days too.

I wish I could help more but there are guys who drag race here that I thought would chime in on the subject.

I don't know if they still do it but with all the high tech stuff they had "minute" drags. You had to launch hard then try to come to as close to a minute as you could before hitting the finish line (1/4th mile drags). The closest to, but not going over a minute, won.
Lee

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RJVolksperformance
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Re: 60ft, wheely and wheelybars questions

Post by RJVolksperformance » Wed May 24, 2017 2:23 am

joosep wrote:
Tue Apr 25, 2017 10:54 am
Is there way to get it under 1.3 without wheelybars or it pulls nose up before I can make it? How far you have gone more since it pulled wheels little up ?

I don't think you will get 60ft under 1.3 seconds on an un prepped track, but it can be done without wheelie bars, this pass I went 1.29 60ft


https://www.youtube.com/watch?v=TVtjQQcIoFg


cheers Richie

gbaker770
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Re: 60ft, wheely and wheelybars questions

Post by gbaker770 » Wed May 24, 2017 6:32 am

There are many different ways to do it. You will need to figure out both the front and rear suspension, tire pressure, and launch rpm. My car is built for a heads up street car class wich requires you run without wheelie bars. It is now consistently 60'ing in the 1.40's. The goal is to get it in the low 1.30's.
Took a lot of time and work to get it there. The biggest piece of the puzzle was the suspension. We also found after pulling it apart to re-do the rear suspension that the framehorns were bent. Dont overlook the front suspension as well. I went through 3 sets of front shocks, they play a huge role in weight transfer. I'm not saying you need a ton of weight transfer, every car is different. It took me tons of passes to get it where it is.
Some people get lucky and get a car that will 60' in the 1.50's right off the bat and are happy with that.

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Re: 60ft, wheely and wheelybars questions

Post by Ol'fogasaurus » Wed May 24, 2017 10:12 am

gbaker770 wrote:
Wed May 24, 2017 6:32 am
.... We also found after pulling it apart to re-do the rear suspension that the framehorns were bent....
One of the reasons that the Truss Bar and the Kaffer Bar (the same thing) is also called a "Traction Bar" by some.

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