|From the Archives: High Clearance Steering for Dana 44s and CJ Dana 30s||Short Cuts|
High Clearance Steering for Dana 44s and CJ Dana 30s
|The author's steering setup.|
|This view gives an idea of how large the flat area on top of the knuckle is. There are knuckle with a flat are that is smaller, but they should be avoided.|
|You can see the raised bosses for the studs in this picture. The knuckle has already been drilled and tapped here.|
|A set of steering arms.|
|Side view of a finshed steering setup.|
|This image shows the location of the dowel pins that provide positive location on the author's steering setup.|
|Another view of a finished steering system|
There has been a lot of discussion about high clearance steering systems for Jeeps latley. High clearance steering has many advantages such as reducing the chances bashing your steering into a rock, eliminating the need for a dropped pitman arm, allowing straight linkages to be used without spring interference on SOA equipped Jeeps and allowing stock steering geometery to be maintained even on highly lifted Jeeps.
The concept of high clearance steering isn't new, in the old days you could make a new cap for the upper king pin bearings on your closed knuckle front end that also had the steering arm built onto it. It wasn't as common then becuase few people did the extreme trails. When open knuckle front ends such as the Dana 30 and Dana 44 became more comon making high clearance steering became more difficult. For many years a dropped pitman arm or bent and re-inforced drag links were considered to be the only option. It is was only recently that high clearance steering has become popular again.
Here is some information and ideas to aid you in selecting, or possibly even designing and building your own high clearance steering setup. *Caution* Steering work is very serious, any mistake can be deadly. The design must be done by a capable person such as a mechanical engineer and the actual fabrication of the setup will require a machinist with prescion tools. This is not a project for a beginner. Accept no compromises in any part of a custom steering setup. It must be perfect, your life and the lives of those around you depend on it.
The most comon knuckles to use are from a '77 or earlier Wagoneer or Chevy 4x4 with an open knuckle Dana 44 front end. These knuckles are common in most junkyards, so don't be misled into paying a premium price by someone claiming they are scarce. These knuckles can be identified by a large flat area on top next to the ball joint. On the underside there will be cast in bosses where the threads will go. On the driver's side Chevy knuckle there will be three studs where the factory chevy steering arm attached. The passnger side Chevy knuckle will be a mirror image but without the studs. Neither side will have studs on a Wagoneer, otherwise the knuckles are identical to Chevy.
The exact shape and thickness of the arms will vary with the application. Generally they are made from 1 inch or 1.5 inch thick cold rolled (mild) steel. The standard convention is to have the holes for the attaching bolts or studs match the bolt pattern of the Chevy steering arm, and mirror it on the passenger side. This puts the threads in the middle of the cast in bosses for extra strength.
If crossover steering is used the passenger side arm will need to be made longer to allow room for the drag link to connect. Often the end of the arm must be curved in for tire clearance. Moving the location of the drag link hole inwards will not have an adverse effect on steering geometry provided the drag link is modified to keep the steering box and steering wheel centered. If "Y" type steering is used (where the drag link connects to the tie rod, not the arm itself) both arms can be made shorter and there will be less chance of interference with the tires.
The holes for the tie rod ends must be located directly above where the original holes were in the original knuckles to keep the steering geometry correct. This takes some effort to design properly and lay out correctly but the effort pays for itself with better road manners, less tire scrubbing on corners, and longer tire life. The best way to accomplish this is to lay out the holes on your original knuckles using a plumb bob. Mark everything in relation to the upper ball joint and then incorporate these measurements into your design. If you are not sure of what I am talking about here it would be best to leave the design and lay out to an engineer or buy a pre-fabricated setup for your vehicle.
The most comon way to attach the arms is to purchase studs and tapered washers at a Chevy dealer and mount the arms the way Chevy did. This is certainly a safe method of attachment. The drawback to this method is that if you have custom arms built your machinist may not have the proper tapered reamer for the holes in the arms. If this is the case it will cost you extra money to purchase the reamer for this one project. The reamer will likley cost over $100 and the machinist will pass this cost along to you. If you are buying a ready made set of knuckles and arms from an aftermarket vendor it is very likley that the arms will be attached by this method.
Another option is to have high strength dowel pins placed between the bolts attaching the knuckles. The machinist would have to ream these holes for a very tight fit, but since the holes are not tapered it is likley that he already owns the tooling. The knuckles on my Jeep use two 1/2 inch dowel pins in addition to three grade 8 allen bolts on each knuckle. The dowel pins are located between the bolts giving five attachment points rather than three. My machinist claims that this is as strong or stronger than using the Chevy style studs and tapered washers and that it locates the arms more positivley. It is important that the dowel pin holes do not go all the way through the knuckle to prevent the dowel pin from dropping into the the U-joint below.
As was mentioned above, correct steering geometry is critical to vehicles opperated on the street. You have probably observed that the inside front tire of a Jeep turns more sharply than the outside front tire to keep the tires from scrubbing. This effect is due to the Ackerman Angle. Placing your tie rods further in or out, forwards or backwards from stock will change the ackerman angle and cause the front tires to scrub when cornering. The scrubbing is not only annoying, it causes a decrease in available traction for cornering at higher speeds. It is very important to locate your tie rod ends accuratley. If you are not sure how to do this please consult an engineer or buy some pre-fabricated arms made specifically for your application.
Bump steer happens when a tire goes over a bump or into a depression and the angle of the drag link in relation to the frame changes. The angle change causes the drag link to push or pull on the wheel, turning it slightly without input from the steering wheel. The greater the angle of the drag link the more bump steer will occur. It is very likley that this modification will reduce bump steer becuase it will result in the drag link being nearly paralell to the ground if done correctly. Bump steer can also be overcome by the use of a track bar that is paralell to the drag link, but track bars also reduce articulation. If the drag link horizontal or nearly so there will be little need for a track bar to prevent bump steer.
Sources for the Arms
There are many aftermarket parts houses selling steering setups similar to those pictured here, although neither of these setups is from any of them. Here is a partial list: Dynatrac, M.O.R.E., Parts Mike, Tri County and others.
Accept no compromises in any part of a custom
steering setup. It must be perfect, your life and the lives of those
around you depend on it.
This information is a personal account of modifications done to two particular Jeeps and is not necesssarily endorsed or encouraged for any other application. As with any suspension or steering modification the handling and safety of the Jeep is affected. In some circumstances this may be dangerous. We are only providing commentary and opinion based on our experience, your experiences could be significantly different. JeepWire.Com cannot predict how any given modification will be used or what it will be subjected to. We do not recommend or endorse this or any product for any specific or general application. Anybody attempting this or any other modification does so at their own risk, we do not assume any liability.
Accept no compromises in any part of a custom steering setup. It must be perfect, your life and the lives of those around you depend on it.