Ride Height

Ride Height: Is the height of your car when it is sitting and the suspension is at the optimum setting (location). I can not stress how important setting ride height is on a chassis.

First, you need to pick out the wheels and tires you will be using in the front and in the rear. The diameter of the tire determines the ground clearance, frame angle, engine angle, shock length and correct angle to weld the front suspension.

After establishing the diameter of the tires, find the front spindle location based on the manufacturer's specifications. The car manufacturers all have specifications on this. If you plan to install a front end kit, the manufacturer should also be able to provide you with this important information.

Take the radius of the tire diameter and use these measurements to set the distance from the ground. In the front measure from the center of the spindle and in the rear measure from the center of the axle. You now have "ride height" and everything should be relative to the ground. Of course the ground or suspension jig should be perfectly level as all your measurements will be made from this origin.

No chassis builder can build a chassis that is tuned with optimum suspension without knowing proper "ride height". How did he know your "ride height" without asking you what wheels and tires you are going to use? Maybe he does not want to know so when your car does not handle correctly he can sell you some additional parts. Remember to ask a salesperson these questions when you are buying. Do they sound credible or just out to make a buck?

Now you are ready to set the engine and pinion angle.

If you have any questions regarding the information on this page please feel free to contact me at moonmr@hotrodheaven.com or 888-875-6666.

Dean Oshiro

Copyright reserved by Dean Oshiro. Reproduction without written approval is a violation of Copyright Laws. Sept 2000

Engine and Pinion Angle

Engine and Pinion Angle: There has been numerous "hear says" about what the pinion angle should or should not be. Hopefully this will clear up a lot of misconceptions. One of the biggest misconceptions is the engine angle is it is relative to the frame. Engine, pinion angle and ride height is all relative to the ground.

Most engines are set at 3 degrees, when you look at the side of the intake manifold on a carburetor engine you will notice the manifold has a wedge in it. This wedge is to allow the carburetor to sit level. The main purpose of having an engine angle is to allow for more room in the passenger compartment by having a smaller tunnel. That is why the car manufacturers build front engine cars with the engine at an angle. Drag race cars have a 2 to 3 degree negative engine angle, the engine will tip down in front. Having this negative angle allow for better weight transfer to the rear of the chassis. The 3 degrees you keep hearing about is the recommended angle for carburetor cars with intake manifolds set at 3 degrees. With the engine and pinion set at 3 degrees they do not line up directly and requires you to make them parallel. This misalignment allow the u-joints to rotate on a street car.

There is a misconception regarding the pinion angle on drag cars. I have seen many people advise that the pinion needs to be 2 - 7 degrees down. In relation to what? I disagree with this theory and set-up. The pinion needs to be "parallel" to the engine angle or in a straight line for the least amount of horse power lost.

This following is a quote from Mark William's web site, "There is a general misunderstanding bout "dropping the pinion down" several degrees. This is a practice that could be applied only to leaf spring cars without any traction control devices where springs can “wrap” and change pinion angle. This practice would not apply to 4-link, ladder bar or torque arm equipped cars. Failure to maintain matched and minimum operating angles increase erratic non-uniform output velocity from the drive shaft to the differential."

You can set up the engine angle at almost any degree just as long as the transmission is perfectly inline with the pinion yoke. However, when the engine and pinion yoke is in direct line, it does not allow for the rotation of the u-joints. This straight alignment is mostly used on drag race cars.

If you would crawl under your car and look at the pinion angle you will notice it is the same angle as the engine/transmission (they are parallel). A good example of having negative engine/pinion angle is when you lower a 1 ton crew cab where you lower the front more than the rear and there is quite a "rake". In this case you have to put a wedge on the back side of the saddles to tip the pinion angle down.

If you are building a chassis you need to first determine ride height. This is the most important thing you need to do. Decide what wheels and tires you want to use before you pick up the welder. If a chassis builder or a salesman does not ask you what tires you are going to use do not buy from him. How can he build your chassis without know the tire diameters? How can he set up the front end and engine angle? What they do is build a chassis based on what they want or think you should have and not what you want.

Now determine the ground clearance you want for your oil pan. Set your motor mounts based on this and the angle to best fits your car. Try to set the transmission directly inline with pinion yoke and if that is not possible set the pinion parallel to the engine angle. Before you weld the brackets on the rear end housing be sure that the rear end was set at "ride height" ride height is where the rear end would be with the car done.

If you find a chassis builder or salesman that says you have to have the engine angle at 3 degrees and there is no other angle you can set if at, find another chassis. He apparently does not understand the principles of setting correct engine and pinion angle. Also no chassis builder can build you a chassis with optimum suspension without knowing proper "ride height".