MiataSource has successfully depowered over 100 NA/NB steering racks with nothing but positive results from our customers. Ranging from stock daily drivers with V8s to track specific race cars. Our process of depowering is the true complete process breaking down the rack completely removing all necessary parts and tig welding the pinion. Here we will talk about what makes the MiataSource Depowered Steering Rack special and what the process we do while answering the common questions we get.
What is a Depowered Steering Rack?
A depowered steering rack is a stock power steering rack that is modified to essentially become a manual non-power assisted steering rack. Removing all the power assisting parts including internal seals, pipes, couplers, etc.
What are the benefits of the Depowered Rack?
Comparing to the OEM manual steering racks, the powered rack has a more desired ratio. Power is 2.8 turns lock to lock vs Manual's 3.3 turns lock to lock. Meaning that for every degree in steering change the wheels will turn faster than the Manual rack. This commonly called quick ratio.
Also removing all the power assisting parts is considered a weight reduction, it isn't anything crazy about 8lbs. But removing of those parts does open up a lot of space to fit a turbo or at least clean up the engine bay a bit as well.
Depowered racks also are considered to be much more responsive vs the manual/loop line/power steering systems.
Are MiataSource Depowered Racks daily able?
This is our most common question and the answer is strictly opinion-based. Is a depowered rack daily friendly? There are a lot of variables that play into the effect. Tire width will cause drag the wider your tires are. It is a minor effect but is noticeable especially with 225 R-Compond on a hot day but this is really just at a standstill. As you roll it becomes easier. Other variants include steering wheel diameter, smaller the wheel the less torque you have to steer. Again these concerns are really when the car is at a standstill. Additionally going from a power to a depowered rack will be a noticeable difference as you are removing power assist in the steering system. But once you moving it will become easier.
Difference between the MiataSource Depowered Rack vs. Looped Line Rack?
I can't stress how different these two methods are. Yes, both will give you a manual steering Miata. But one will be a much more difficult and less effective mod. Looped line rack is removing all the power steering components and essentially taking some rubber hose and connecting the high side and low side pressure ports of the rack so the fluid loops out and back into the rack. This is the cheapest way to depower your rack. It works and is used but there are some problems with that.
Looped Line leaves all the internal seals and fluid inside the rack causing an issue of drag within the rack. This can make the steering feel heavy. There is an internal seal on the main shaft:
This seal is used when the pump pushes fluid to one side of the seal assisting the rack to turn left or right, but left in just causes a drag. MiataSource depowered rack that seal is removed:
Another problem with the looped line method is leaving the pinion shaft unwelded. Before welding, the pinion shaft has a very slight movement which is used to direct the rack where the fluid is pressured to the rack. If left as-is you will notice some slop or dead play in the steering system. The MiataSource racks pinions are fully TIG welded:
What additional parts are necessary to install?
Cars with OEM power steering racks:
For those replacing their OEM power steering rack with a MiataSource depowered rack, you can reuse your existing inner/outer tie rods and mount bushings. Recommended replacing these components when installing the MiataSource Rack. You will also be required to get an alignment.
Cars with OEM manual steering racks:
For those replacing their OEM manual steering rack with a MiataSource depowered rack, you will be required to purchase inner/outer tie rods for a Miata equipped with power steering for your specific year. You will also need to purchase the steering rack mounts and bushings.
What is our process?
We start with an OEM Miata powered steering rack, we do a complete dismantle down to all individual parts, we remove all unnecessary parts. We then examine all the bearings and parts that retain in the depowered rack and replace them if necessary. Then once all parts are good we ultrasonic clean all the parts to clean out any old grease/oil or debris.
Once the pinions are removed we ultrasonic clean the entire pinion to prepare for welding. We then TIG weld them in house.
We take the steering shaft and remove the internal seal and on some racks remove the internal seal on the housing.
Once everything is modified and ready for assembly we take the housing, degrease it or all the grease built up for the last 20 years. We then ultrasonic clean then sandblast/sand down the paint to raw metal and paint the housing. All hardware is then also sandblasted removing any corrosion. During assembly is where we replace any bearings, bolts, hardware that is kept. All hardware is torqued to spec.
At the end of assembly due to all the lines and fittings, we removed we install our MiataSource Depowered Plug Kit. Which in the end you get a completely 100% truly modified depowered steering rack, ready for install.
If you are interested in ordering a MiataSource Depowered Rack links follow:
Local customer with a MiataSource Depowered Rack in his Exocet.