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B4 Steering Geometry

B4 Steering Geometry

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Old 10-05-2014, 10:13 PM
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Default B4 Steering Geometry

Hey, I'm trying to figure out how to take some caster out of the front end of my B4FT. I've got some 25 degree caster blocks on there now, but I'm wondering if taking out more of it would help.

I'm running on carpet, with very low jumps. The car has Pro-Line Wedge Z3 tires up front and Pinpoint rears. The buggy just plows into corners with any degree of speed involved, but really grabs once it's slowed right down.

I'm guessing getting the tires a little more upright by adjusting the camber and caster would put more tread on the ground, as opposed to the knife edge I'm getting at full lock now. Thoughts?

Jim
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Old 10-06-2014, 05:46 AM
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Default Try the 20 Degree Caster Blocks...

Originally Posted by monkeyracing View Post
Hey, I'm trying to figure out how to take some caster out of the front end of my B4FT. I've got some 25 degree caster blocks on there now, but I'm wondering if taking out more of it would help.

I'm running on carpet, with very low jumps. The car has Pro-Line Wedge Z3 tires up front and Pinpoint rears. The buggy just plows into corners with any degree of speed involved, but really grabs once it's slowed right down.

I'm guessing getting the tires a little more upright by adjusting the camber and caster would put more tread on the ground, as opposed to the knife edge I'm getting at full lock now. Thoughts?

Jim
Jim,

You could give the 20 Degree Caster Blocks a try. They are Associated Part Number 9592.

However, if you are looking for corner entry you may be going in the wrong direction as less caster reduces corner entry steering.

The issue could be a few items:
1. Do you have the best tires for the track?
2. Does the insert of the support you need for the front tire in such a high traction track.
3. Shock setup too thick and not allowing weight to transfer to front fast enough
4. Over-driving into the corners. This is really easy to do on carpet racing due the the traction and speed generated on carpet.

I would suggest staying at the 25 degrees and play around with camber and camber link locations as well as your front shock package to find a good balance.

Good Luck!
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Old 10-07-2014, 12:38 AM
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Originally Posted by JFuel11 View Post
Jim,

You could give the 20 Degree Caster Blocks a try. They are Associated Part Number 9592.

However, if you are looking for corner entry you may be going in the wrong direction as less caster reduces corner entry steering.

The issue could be a few items:
1. Do you have the best tires for the track?
2. Does the insert of the support you need for the front tire in such a high traction track.
3. Shock setup too thick and not allowing weight to transfer to front fast enough
4. Over-driving into the corners. This is really easy to do on carpet racing due the the traction and speed generated on carpet.

I would suggest staying at the 25 degrees and play around with camber and camber link locations as well as your front shock package to find a good balance.

Good Luck!
Thanks for the advice. I won't have a chance until next week, but it appears I'm homing in on something. The tricky thing is camber. With the front kick up and the nature of the vehicle, there's a large amount of camber gain as the wheels steer. Once at full lock, only the edge of the tire is contacting the surface. Even with these very aggressive tires it's limiting traction.

To address your points:

1. I think these are the best tires, but i will try some grooved and even slick front tires next race day.
2. There is no insert on the new Prolines. Theyre extra skinny and have very stiff sidewalls.
3. My shocks are setup pretty light, with 30wt all aroun. i could mess with springs.
4. Over driving. That's probably a good portion of it, but it's like over driving on ice - easy to do.

One thing i hadn't considered is rear traction. I may actually have too much and it won't allow the vehicle to rotate. Brand new, very aggressive rear carpet tires may be a factor.

Thanks again.
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Old 10-07-2014, 04:05 AM
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Originally Posted by monkeyracing View Post
Hey, I'm trying to figure out how to take some caster out of the front end of my B4FT. I've got some 25 degree caster blocks on there now, but I'm wondering if taking out more of it would help.

I'm running on carpet, with very low jumps. The car has Pro-Line Wedge Z3 tires up front and Pinpoint rears. The buggy just plows into corners with any degree of speed involved, but really grabs once it's slowed right down.

I'm guessing getting the tires a little more upright by adjusting the camber and caster would put more tread on the ground, as opposed to the knife edge I'm getting at full lock now. Thoughts?

Jim
UK racing has been on this kind of surface for a long time and I have a fair bit of experience tuning the B4 for these conditions.

Fundamentally, you will always struggle for steering due to the nature of the car. The rear end of the car has lots of grip but when it breaks away, it does it dramatically. Mid-motor cars have been the most popular choice in the UK for years for this very reason.

The steering geometry isn't going to transform the car. I've run the B4 with all the caster options and it always feels best with 30 degrees.

Tyres are a big one. The Pro-line tyres are a copy of the Schumacher Minipins/LP Cut staggers but in an inferior compound. If you can get hold of the original Schumacher tyres (in Yellow) you will be at a good starting point. Schumacher Minipins on the front will give more steering but I find them too edgy.

You can make a small improvement to the car by adding weight near the front axle. A heavier bulkhead and some stick on weights around the servo can get 40-odd grams over the front end which helps, but is still no where near the weight distribution of a mid-motor car.

There are small balance changes to be found in springs, damper and linkages too.

But at the end of a the day a quick car on carpet is a mid-motor car running Schumacher tyres.
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Old 10-07-2014, 04:21 AM
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Mm on carpet, as said, is likely to be quite a bit .faster
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Old 10-07-2014, 08:44 AM
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Did you use the "wedge" or the "wedge squared" tires?

If you were running the "wedge", you could try the "wedge squared" which should give more steering.

Some of the Schumacher tires might be worth a shot too.

Believe most of the European carpet tracks are AstroTurf which would be a bit different than the Ozite at Karz...
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Old 10-07-2014, 09:19 AM
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Hey Jordan. Wedge squared. I'll have to do some testing next week with the tweaked geometry and spring rates. Can't see putting any more weight in it. The giant battery is plenty heavy.

Once I get that sorted out, I can figure out gearing. The thing is fast no matter what - need to find the right kind of fast.
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Old 10-07-2014, 09:22 AM
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Please use the existing B4 thread. no need to create a new one.
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