Wheel base vs. Track Width

Tech Tim

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This has been covered before but within constraints of certain classes. Like "What is the best wheelbase for X class or "How much track width can/should I run for class Z".

Is there a formula, guide or rule of thumb when it comes to track width vs wheelbase?

The longer the A-arms in front the more travel we can get without have dramatic geometry changes. The longer the wheelbase, the more stable through the bumps.Get WB to TW package too square and the rig gets a little squirrely. Get the WB overly long, vs the TW, you are stable, but could be wasting useable A-arm length.
 

DUMP!

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This has been covered before but within constraints of certain classes. Like "What is the best wheelbase for X class or "How much track width can/should I run for class Z".

Is there a formula, guide or rule of thumb when it comes to track width vs wheelbase?

The longer the A-arms in front the more travel we can get without have dramatic geometry changes. The longer the wheelbase, the more stable through the bumps.Get WB to TW package too square and the rig gets a little squirrely. Get the WB overly long, vs the TW, you are stable, but could be wasting useable A-arm length.

That depends entirely on what the rigs intended use is for. For desert racing you don't want the track width much more then about 90-92 inches any more and you are going to be braking your own trail so to speak because the tires are going to be running on a part of the course that most other cars are inside of. Any less then about 88-85 and your going to find the car wanting to fall off the hump in the middle of the road. This is speaking strictly from a Trophy Truck or class one point of view. As for wheel base most all of these class vehicles have evolved into about the 124-125 inch wheel base range. Very much longer and they don't turn very well, any shorter and they beat you up in the rough.

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Tech Tim

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Thanks for chiming in DUMP.

First off, I should clarify track width. From what I've read on this forum, TW is defined Outside edge of tire to outside edge of tire, correct?

DUMP said:
That depends entirely on what the rigs intended use is for.

That's why I was wondering if there was a formula for TW to WB. Like you want to keep your TW between 70 to 80% of the wheelbase or you want your WB to be 10-15% longer than the TW.

DUMP said:
Any less then about 88-85 and your going to find the car wanting to fall off the hump in the middle of the road.

By falling off the hump you mean that the rig will continually be pulling right or left because of the hump in the road correct?
 

DUMP!

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Thanks for chiming in DUMP.

First off, I should clarify track width. From what I've read on this forum, TW is defined Outside edge of tire to outside edge of tire, correct?

YES



That's why I was wondering if there was a formula for TW to WB. Like you want to keep your TW between 70 to 80% of the wheelbase or you want your WB to be 10-15% longer than the TW.

I dont' know of any



By falling off the hump you mean that the rig will continually be pulling right or left because of the hump in the road correct?

YES

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Triaged

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According to SAE Track Width is the lateral distance between the center of the contact patch.

Assuming a 12.5" wide tire in DUMP's example and dividing wheel base by track width you get a range of 1.56-1.72. Some of the stuff I have done has fallen around a 1.6 wheelbase to track ratio which is about in the middle of DUMP's range. A CORR Pro2 is at 1.45 by the rules while a new Mustang is at 1.72.
 

DUMP!

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Derek-
are we gonna get to finish our trucks or what?!?!?!
-Benji

I sure hope so, but I don't think it will be anytime soon. I also don't know if I would want to, those truck where designed with certain things in mind. I've heard that they may want to start changing those things due to cost. Not sure if I want to be involved in a re-hash or a "yea we can make that work" mind set.

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Tech Tim

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According to SAE Track Width is the lateral distance between the center of the contact patch.

That's why I wanted a clarification. OE use the center of the tire, us rock crawlers usually discuss WMS to WMS (Wheel Mounting Surface) and not track width and here they use OEoT to OEoT.

Assuming a 12.5" wide tire in DUMP's example and dividing wheel base by track width you get a range of 1.56-1.72. Some of the stuff I have done has fallen around a 1.6 wheelbase to track ratio which is about in the middle of DUMP's range. A CORR Pro2 is at 1.45 by the rules while a new Mustang is at 1.72.

Thanks for the numbers.
 

Tech Tim

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If you are using pre-made steering arms, maybe.

By designing your own, you can place the TRE or heim where you need it for the optimum AA for your particular wheelbase and track width.
 

Moss2

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Depending on your class and travel, I think it may be an advantage to be a little bit narrower, ride the humps and stay out of the big holes and braking bumps.
 
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