These eccentric lower control arm lock washers were initially developed by Split Street Motorsports.
On the FD front and rear subframes, where the lower control arms connect, there are eccentric bolts and washers hat allow for adjusting suspension settings. These eccentric bolts/washers are fastened/rotated in various different positions thus pushing the LCA's inward or outward which decreases or increases the camber of the wheels.
The factory eccentric bolts use washers on both ends; these washers have markings which help when making adjustments and finding the desired camber setting. In order to keep the eccentric washers and bolts in place the subframes have welded on U “guides”. This method works great and some FD owners will never have any issues with the factory eccentric washers and bolts.
One of the downside of the factory OEM eccentric washers is that anytime the LCAs are taken off for whatever reason…ideally you would want to get your suspension alignment dialed in again. There is also a chance of eccentric bolts slipping during hard cornering, especially if using new sticky tires in combination with old tired bolts/washers.
So this is where the eccentric lock washers come into play. They fully replace the factory washer (on the nut side of the bolt), and as you can see on the following image they also use an outer ring. The outer ring sits perfectly against the walls of the factory welded on U “guides” which prevents any left-right movement. Also notice the inner washer is secured inside the outer ring using “teeth” which ensure the inner washer cannot spin out of place.
Other than the obvious benefit of completely eliminating any slipping or movement during hard cornering, the lock washer can also be used to dial in certain alignment settings, which you can easily revert back to anytime the LCA’s are taken off, without having to go back to the alignment shop. Or for example, one could always have a street and track setting which they can easily change on the spot by simply adjusting the inner washer to a different position. It’s easy to keep track of the positions as you simply mark the teeth with a sharpie perhaps.
Product feature list:
- CNC laser cut lock washer set (6x inner, 6x outer) - (4 washers for the front LCA’s (2 per side) and 2 washers for the rear LCA’s (1 per side) 1 set includes the washers you need for 1 FD RX7
- 304 stainless steel
The initial eccentric bolts utilized in the FD RX7 were the D shape, whereas updated bolts or newer cars have the H shape. Please verify what is on your vehicle when ordering.
As mentioned in the during product development, some subframe “horseshoe” or “U” welds are wider and some are narrower in width. Due to this, the outer lock washer ring has been cut a bit wider than the average size. Some of you that have narrower U horseshoe welds might have to grind off a bit of material from the sides of the outer washer, which is not that hard, just make sure to grind both sides equally and try to keep the straight part of the outer washer flat to the grinding surface. Best way would be to place a sand paper sheet on a flat surface and then grind each side equally. At most you will have to grind off 0.05 to 0.15mm of material per side, no more than that should be necessary. This will ensure you have a nice and tight fit. Best practice would be to go slowly step by step and after you grind of a bit try to set it into the U weld and see how it fits.
Original product development info can be found here: