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Author Topic:   measuring wheelbase ?
brownstone
Dirt Freak

Total posts: 284
posted April 07, 2005 06:05 PM  
Ok needs some suggestions please. I am trying to measure wheelbase, I have tried having someone hold the tape measure and going from the bottom grease zert to the center of the axle but this not working well, body and other things are the way so the measurement is not accurate.

How do the rest of you measure wheelbase on your car ?

Any help is appreciated.
Thanks !

Rat Trap
Dirt Maniac

Total posts: 129
posted April 07, 2005 06:45 PM  
use a plumb bob (i think thats what its called) (string with a weight on the end of it) Hook it to all 4 corners, make a mark on the floor, move the car out of the way and measure to your marks.

brownstone
Dirt Freak

Total posts: 284
posted April 07, 2005 07:02 PM  
ok thanks, now on the back should I measure to the center of the axle tube on each side and then hold the plumbob on that mark and drop it to the floor ??

On front I am assuming that I would hang the plumbob off the center of the spindle with the grease cap off ?

Again thanks !!

Rat Trap
Dirt Maniac

Total posts: 129
posted April 07, 2005 07:27 PM  
on the front we come off the center of the lower ball joint. Coming off the center of the spindle with the dust cap off can give you a false reading, because then caster and toe come into play plus haveing to have the wheel straight.

On the rear we come off the center of the axle on each side. This is also how we check to see how much rear steer or square our rear end is also. after we do this and have it all set where we want it we will take another measurement from the rear axle to some other place forward, for us its the frame and use those measurements for reference later on if we need them. Hope this helps.

Istock66
unregistered Total posts: 129
posted April 07, 2005 07:36 PM           send a private message to Rat Trap   Edit/Delete Message   Reply w/QuoteBBBBBB
Are you trying to see if your car is square or just want the wheel base??

to determine wheelbase

set your toe to straight up

hook the tape on the front of the front wheel between the wheel and tire and measure to the front of the rear wheel you can do it by yourself


autoshop
Dirt Freak

Total posts: 298
posted April 07, 2005 08:19 PM  
Here's how I do it I drill out a pair of zerk fittings and run a string thru the hole with a plumbbob on the end of the string,and then go to the rearend and measure off the hubs the same length in to clear any mounts and drop a line from that point and measure forward and cross wise.Some times you can use the axle bolt to drop a line from. That will give you the center of the rearend to the center of the front.

joeltjen
Dirt Maniac

Total posts: 182
posted April 07, 2005 10:28 PM  
we have four big washers with holes drilled in them for plumbbob strings turn your hub so you have 1 wheel stud on the very bottom. you can put a 6 inch level across the top two and turn the hub so you know when its straight down. hang the washer on the bottom stud making sure it swings freely. we put a strip of duct tape on the floor and use a ball point to mark where the plumbobs hang. you can now connect the front 2 marks and back 2 marks and measure wheelbase. if you know where the center points are on your chassis you can also run a line down the middle of the car and check front and rear wheel lead and axle squarness and offset. john

[This message has been edited by joeltjen (edited April 07, 2005).]

brownstone
Dirt Freak

Total posts: 284
posted April 08, 2005 05:56 AM  
Thanks to all I will give it a shot car is pushing like a tank and I want to measure the wheel base to see if the rearend is leading.
Thanks !!

superdave
Dirt Freak

Total posts: 280
posted April 08, 2005 04:36 PM  
Please don't measure your wheel base from the ball joints and rear axle. When it's measured at the track they will use a long gauge center to center of the wheels. When you add caster you tip the knee (upright portion of your "spindle") back and that moves the he spindle and center of the wheel back. Add toe out and it moves back even more. Many a car has been disqualified because they didn't take into account what the alignment settings would do.

Good luck,
Superdave

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