Too much traction - paddle tires

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Booga-dune-poon
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Too much traction - paddle tires

Post by Booga-dune-poon » Thu Dec 26, 2013 5:54 pm

How can I have too much traction you ask?
Symptoms:
I can not break the wheels loose when climbing very steep hills. I bog down in second gear and must down shift to first gear, but I loose momentum and ultimately fail to get to the top.

I can hardly break the wheels loose when making a sharp turn even on flat sand!
In this picture I'm using the turning brakes to at least make it look like I'm kicking up a little sand.
Image
The specifications:
Xtreme Sand Squirt 13.00-15
Wright Gear Box - Pro Sand conversion
1914 c.c. VW, Dual Weber IDF 40's, Mallory Distributor SVDA, 044 Heads, Engle 110 cam, blah, blah, blah. It's a VW and I'm guessing maybe 100 horses (pony's?).

So I've decided to mess with the tires. To change the height of the paddles to be more exact. Maybe if I can get a little more slip I can keep the engine up in the power band and make up for lost traction with increased wheel speed while climbing.

The tires have about 4 seasons on them. Measuring between two paddles I get 11/16" height.
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Kevin

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Re: Too much traction - paddle tires

Post by Booga-dune-poon » Thu Dec 26, 2013 6:41 pm

Thinking out loud, how much of an increase in horse power would spin these tires on my sand car? Maybe 30 more horses?
Ok, so what if I made these tires use less power? I'll shoot for 1/3 less paddle height and see what happens. There's no way of knowing for sure if this will work until I get out there. I can't un-cut the tire later. But 1/3 sounds like a conservative number (he said to himself).

11/16" = .687" existing paddle height
.687" x .33 = .226" off each paddle
.461" = new paddle height

Go to hardware store and get a knife used to trim linoleum flooring. I found some 1/2" thick wood molding that I cut for a guide.
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Kevin

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Re: Too much traction - paddle tires

Post by Booga-dune-poon » Thu Dec 26, 2013 6:54 pm

Wash, rinse, repeat. Each tire has 16 paddles.
Image

I used a 4 1/2" grinder with flap wheel to feather out the rough edges. Good thing it was a windy day as the smoke really smelled like I was at the drag strip.
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New paddle height measures to spec.
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Before and after
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Next dune trip coming up. I'll post results when I return.
Kevin

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Re: Too much traction - paddle tires

Post by Vincent J Brunasso » Sun Dec 29, 2013 12:11 pm

If cutting down the paddles appears to be on the right path, I'd suggest a little more tire pressure to see what happens.

I've heard of some cutting alternating halves off the paddles. That's a radical move IMHO - and you can't go back if it doesn't work. I suppose then you could go to Skat Trak and have new paddles glued on. If you get to that, then would be the time to consider fewer paddles - maybe 14 instead of 16.

I realize the following is not what you want to hear, but I think that there's just too much car for the engine. It looks like a 4 or 5 seater. How much does it weigh? You may end up being able to break the wheels loose but still not get up the hills. As the saying goes, there's no replacement for displacement.

Good luck and keep us posted.
Vincent J. Brunasso
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“My reading of history convinces me that most bad government results from too much government.”
--Thomas Jefferson

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Re: Too much traction - paddle tires

Post by Booga-dune-poon » Mon Dec 30, 2013 7:12 pm

The car weighs 1,600 lbs. I also use it for cross country desert and it's really beefed up with bracing and full skid plates. It seats two adults and two children (36" wide bench).

Yes, it's too much car for this motor. I'm unwilling to spend more on a VW engine. No strokers or turbos for me. Very poor bang for the buck. Looking back this was my mistake in motor choice before I built the car. If this engine was a computer it would be an old IBM PC 8086 / 640 kb memory / dual 360K floppy disk drives / DOS 3.1

But, to change out to a Subaru or Ecotec would require a new transaxle, adapter and the whole wiring harness thing. If we go that route I'll also need frame modifications, cooling system and coil over shocks in the rear. As it now stands I couldn't get anything close to what's already in the car.

Having built the car myself, I'm emotionally invested in this over priced / under performing money pit :oops: .

Having said all of that, I'm encouraged by stories that performance can be improved by the right tire setup. On race day, more time and energy is actually spent on tires trying to find the "setup". I'm no racer, just hoping to ring out the last 5% of potential.
Kevin

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Re: Too much traction - paddle tires

Post by Vincent J Brunasso » Thu Jan 02, 2014 5:33 pm

I have a buddy that runs a Corvair with the same trans you have. Might be the easiest swap.
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Re: Too much traction - paddle tires

Post by WoodIsGood » Sat Jan 18, 2014 4:10 pm

This was my approach to a similar problem with my quad: http://www.americansandassociation.org/ ... 11&t=27303 Worked wonders in helping me run with the higher HP quads. Last weekend a friend borrowed a set of my cut paddles for his 400EX with a 440 kit on it and he was shocked by the increase in performance he got; kept thanking me all weekend for the use of the tires. Said he was going to modify his paddles before his next trip.

That all said, it is certainly true that there is only so much that tire mods can do to increase performance.

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Re: Too much traction - paddle tires

Post by Booga-dune-poon » Mon Feb 03, 2014 7:56 pm

I just got back from a sand dune trip to Glamis over the Superbowl weekend. I'm happy to report that the now trimmed paddle tires worked even better than I had hoped. I can now keep the engine in the power band with the tires spinning at a faster speed because they do not move as much sand per revolution. The added bonus is I get more tire revolutions per linear feet of travel so net / net I get more push and the engine works in the sweet spot to output more hp.

For example: Competition Hill is whooped out at the bottom. My car does not have long travel, so I must keep my approach speed at about 1/3 throttle in 2nd gear. Once I get past the real choppy stuff the hill is already getting steep. In the past I couldn't accelerate up the hill in 2nd gear because the tires hooked up too much and I would ultimately bog down and be forced to downshift to 1st gear and then just redline the rpm's to make it up to Osborne Overlook. Now I can get the tires to break loose, the engine stays in the power band and I'm actually moving much faster now than before. I just cruised all the way up to Osborne Overlook in 2nd gear and I felt better not abusing the car like I'd done in the past.

It's just more drivable because I can break the back end loose in turns if I want to. This allows me to steer the car with my right foot by lining up the front end towards the intended direction rather than plow through turns. Much more fun too!

Bottom line, I think the car is now better performing because the tires match the horsepower of the engine.
Kevin

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