When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I picked up a CP Racing rack and pinion conversion from the junkyard last week. It seems to be in good condition and I am thinking of installing it in my racecar. I read everything I could find on the forum about it. There were lots of negative comments back in the day, but most of them seemed to be related to customer service. The main issue that seemed to pop-up that could make a difference is the aggressive angle of the shaft connecting the steering column and the R&P. It looks like this set-up is the second or third generation, so the problem may have been resolved. The other two noted problems: blocking oil drain plug and interfering with the oil pan appear to have been resolved with this set-up.
I am wondering if anyone has some long-term useful experience to relate to me. Especially racing experience. It would not be a huge effort to go back to stock if it doesn't work out, but I would rather avoid that if I can.
Honestly, I thought it was power steering when I got under the car haha , you are lucky I didn't slice the boot open, I was curious to see what was behind it but my dad wasn't too comfy with me under the car.
The tubing actually seems to be pretty thick wall. My ultrasonic thickness measurement gauge is not working so I can't verify tho. In any case, round tubing is stronger than square for same general dimensions. Installed in the chassis at the yard it seemed solid. I am thinking I will find out. :-)
Frogman - Your dad may not have been too comfy with you under the car, but he looks pretty comfy on the sofa in the background of the pic you took of the side view mirror. ;-)
The tubing actually seems to be pretty thick wall. My ultrasonic thickness measurement gauge is not working so I can't verify tho. In any case, round tubing is stronger than square for same general dimensions. Installed in the chassis at the yard it seemed solid. I am thinking I will find out. :-)
Frogman - Your dad may not have been too comfy with you under the car, but he looks pretty comfy on the sofa in the background of the pic you took of the side view mirror. ;-)
Carl
Haha, I didn't even notice! Are that rack and pinion unique to that setup? The reason I didn't touch it was because it didn't look like my rack and pinion and the idler arm was obviously not there , that and the fact there was oil everywhere, I used a few shop rags and purple power to clean the area ..
In stock form there is no rack and pinion on the SA or FB. Just the steering box and connecting links. I am not an expert on steering systems, but pretty sure the idler arm just anchors the right hand side. Kind of acts like a passive pitman arm on the right side. Keeps all the other arms moving in the right direction. If you didn't notice, the idler arm is attached to the same holes that would be use for the steering box on a RHD car.
There were 2 versions of the CP rack and pinion kit.
I had one of the earlier versions, yours is one of the later versions, with the tubing construction.
I took the kit off my car, because the geometry was so bad.
The biggest problem was that the rack was not centered to the cross member, and the one steering arm was much longer than the other. This caused the Ackerman angles to be different for left turns and right turns. The second problem was that the steering did not return to centre after a turn. I felt like there was zero caster built in, although the factory caster was unchanged.
The third problem was the slow turn ratio.
I also was not happy with the weld quality of the kit, especially where they welded the tie-rod extension piece on. I would not have felt safe leaving this contraption on my car, and I doubt it would pass any serious racing tech inspection.
The only improvement was that there was no steering free play when driving straight.
It ended up in the scrap bin, as a community service.
Hhmm. So far I have two "for" (one by PM) and one "against". Seems like I will give it a try and see how it works. It won't be too hard to go back if necessary. The actual construction of this version seems sturdy so should be OK in that department. It will be interesting to see if bump and ackerman turn out to be an issue. I am thinking they it should be less of an issue on a race car with much stiffer springs and no full lock steering, but.......
Carl I'm definitely interested in seeing how it works for you! if it works well I may have to crawl under your car and snap some pics so I can fab something similar I've been thinking of a manual-rack conversion for both Mozu and Carasu
Now that I have just sold my car and sadly watched it get towed down the alley, I guess I should finish out my experience with the CP rack and pinion. It has worked fine in my race car since I installed it in Feb 2022. The steering is much lighter and more responsive. It has the same steering ratio, so the lock-to-lock is the same as stock. It took a little fiddling to get the steering column adjusted properly, but once that was done, it has been good. The only problem I had was that the nuts on one of the u-bolts locating the rack came loose at the beginning of an enduro. Red loctite and retightening seem to have solved that problem. So far the r&p has gone through 4 test days, equivalent of 11 SCCA sprint weekends and 2 Lucky Dog enduros. I like it just fine. Hopefully it works as well for the new owners. I am sure Conekiller will let me know ;-)
This info is probably moot since CP Racing has been gone for a long time. I just don't like to leave things hanging. I suspect the MTheory r&p is probably nicer, but those may no longer be made either. Also pretty expensive.
Now that I have just sold my car and sadly watched it get towed down the alley, I guess I should finish out my experience with the CP rack and pinion. It has worked fine in my race car since I installed it in Feb 2022. The steering is much lighter and more responsive. It has the same steering ratio, so the lock-to-lock is the same as stock. It took a little fiddling to get the steering column adjusted properly, but once that was done, it has been good. The only problem I had was that the nuts on one of the u-bolts locating the rack came loose at the beginning of an enduro. Red loctite and retightening seem to have solved that problem. So far the r&p has gone through 4 test days, equivalent of 11 SCCA sprint weekends and 2 Lucky Dog enduros. I like it just fine. Hopefully it works as well for the new owners. I am sure Conekiller will let me know ;-)
This info is probably moot since CP Racing has been gone for a long time. I just don't like to leave things hanging. I suspect the MTheory r&p is probably nicer, but those may no longer be made either. Also pretty expensive.
Kind of weird not having an RX7 after 25 years
Carl
I still remember finding that rack on the car and being super confused what it was when taking the springs off !
Are you going to buy another Rx7 or are your rotary days over ?
My personal RX7 days are over, but one of my racing buddies still has several (at least 9 in various stages of undress. Yep, he is a bit whacked!) that I am sure I will be involved with keeping race ready for a long time. My personal project is getting a 1930 Ford Model A pickup truck together that I have had since 1972, 6 months before I could get my drivers license ;-). For racing I have gone over to the dark side with a Spec Miata. It matches my racing interests and goals better these days for various reasons. The RX7 was great though. Was pretty choked up watching it get towed away down the alley this morning.
My personal RX7 days are over, but one of my racing buddies still has several (at least 9 in various stages of undress. Yep, he is a bit whacked!) that I am sure I will be involved with keeping race ready for a long time. My personal project is getting a 1930 Ford Model A pickup truck together that I have had since 1972, 6 months before I could get my drivers license ;-). For racing I have gone over to the dark side with a Spec Miata. It matches my racing interests and goals better these days for various reasons. The RX7 was great though. Was pretty choked up watching it get towed away down the alley this morning.
Carl
We all have our reasons , You car was really sweet and I'm lucky I got to see it in person . Some times I want to sell my car too after 7 years but it got me through law school and I genuinely do enjoy it aside from the long warm up time and bad mpg. My dad has his Falcon Futura that he has had for 32 years which he has never gotten around to finishing . Maybe I will help him !
I have not noticed any weird steering issues, including bump steer. It might be because I have stiff racing suspension, so not much travel. In the process of lowering the car, I also added the spacers between the bottom of the strut and the steering knuckles. Or maybe I am just an oblivious driver. As an enduro car though it was driven for long stints by a number of people including 3 experienced Spec Miata drivers and two long time RX7 racers. Everyone seemed happy with the handling. The new owners may notice something that I didn't though.
Jeez, CP Racing is a name I haven't heard in a very long time. I had a chance to drive a car with one of their kits once back in the day at one of the Ottawa meets. I liked the lack of play in the middle, but it must have been a version 1 kit because it definitely had the bump steer, return to centre, and asymmetric left/right turn issues. The fella driving that car ended up flipping it onto its roof in a Fitch a few hours later that day with his pregnant wife in the passenger seat after taking a sandy corner too fast. Wild day.
I ended up getting a RESpeed Rack and Pinion conversion years later which I'm still using. It isn't perfect but I'm generally pretty happy with it. I love that it switched from rear steer to front steer because now that 14mm caliper bolt is no longer such a pain in the *** to reach, and swapping a motor with a differently shaped oil pan wouldn't be an issue. I also love how beefy the replacement front crossmember is.
I haven't read up much on the MTheory kits, but he chimed in the other day that he's not gone, so hopefully there's still an option out there for people.
j_tso - that wasn't me, I never had a CP racing kit as they stopped making them before I had enough cash to get one. Glad to see a few people remember my name at least since I don't post very often anymore!
I did get one of the early Re-speed kits, and about a year later a second one for my other FB. Initially I loved them (hence buying a second) since it got rid of the dead center/wonder steer of the original box, but it wasn't without it's tradeoffs. In my opinion at least, they went too far in their attempt to improve Ackerman (this was done by replacing the steering knuckle with one that is straight) and it made sharp steering angles, such as maneuvering in a parking lot cause the outer tire to scrub (ie, turned too far) quite badly. Additionally the angle of the "rear" control arm that they added (effectively making it an A-arm) tended to wear the bushings out quite fast. At the time (this is going wayyyy back) I think I was one of the few on here who was daily driving their FB with the re-speed kit 70+ miles a day so I racked up probably 25k miles on it in short order - many of the worn parts and general shortcomings of the kit were probably more apparent on mine than others.
Long story short I got tired of the scrubbing tires on a street car and ended up going to an FC subframe in 2011, which I have redone, modified and tweaked over the years. I sold my Re-speed kits shortly after and I am very happy with the FC setup I have on my cars now - although I did pick up a Miata subframe a few months ago so you can guess where this is going
I've got the respeed kit too. While I want to like it, I have the exact same feeling. It actually has 0 ackerman, which sucks at low speeds as the tires are parallel. Once you are moving it is okay but low speeds are AWFUL. I have grippy tires and a locked diff, extra terrible combo with no ackerman, lol.
I've tried to sort it out but since it is a front steer conversion, you cant move the tie rod end out far enough without hitting the brake rotor. In a rear steer you move the tie rod in to increase ackerman but front steer it has to move out. Theres just no room.
The reduced ackerman was definitely not intentional, it was a limitation of the design. It can be improved with a rod end or an adapter between the strut and steering knuckle, but there's no good way to solve it. The rear "control arm" design straight up sucks. I was going to redesign the whole thing but I just picked up an FD so that's on the backburner.
Unless you are changing the struts/knuckles/hubs, the car really only supports rear steer.
Interested to hear what comes of the miata subframe, but its unfortunate someone hasn't knocked an R+P conversion out of the park yet. I think MTheory was the closest, unfortunately my setup needs to clear an FD oilpan (which is the only thing the respeed kit does well, haha)
-Alex
Edit: CP racing actually sold that? Crushed tubes and booger welds, lol. If people would buy that, I should start a shop haha. I'd be hesitant to run it but the angle of the joints look fine to me.
^ Glad I'm not the only one! Also you are correct, I worded my statement incorrectly - it was more of a packaging limitation on their part with the steering knuckle. They did what they could, but in the end the Ackerman sucks. In theory you could move the pivot point out farther if you ran big enough wheels (probably 17 at minimum), but anything smaller (like most of us run) means the outer tie and the wheel want to share the same space...
Also agree, The MTheory kit looks great, but running an FC engine (with the FC oil pan) or FD engine (again with FD oil pan) pretty much negates the possibility of keeping it rear steer.
Shortly after buying the Miata parts we had a death in the family so it got put on the back burner. I have to get some things sorted before getting back to it, but it will happen for sure.
The M theory Kit is so pricy . I have been putting away 350$ a month and im still a grand short 😂😂.
My steering is pretty great but the small amount of wandering is pretty evident at certain speeds .
Man...just found this thread or I'd have responded sooner...especially with Carl's mention. So, after My team buying Carl's car and hauling up to the Portland area we immediately did a track day and all members of my team got a chance to drive it at speed. Of all the things Carl had done to the car and set up, the steering was one of our favorites. No noticeable bump steer, no differences left to right and most importantly, no dead zone. The only weird thing we encountered was the driver side outer tie rod end is different than the passenger side. The drive side outer has a much larger body. Where that became a problem was when we tried to change wheels. The wheels and tires Carl had on it for storage were quite and bent and the tires severely flat spotted. He had it set up with adapters/spacers to run Miata wheels. We removed the spacers to install a spare set of our primary race car wheels, Koenig Rewinds with standard GS fitment, and found the driver side wheel made hard contact with the tie rod end. No issue on the passenger side. Kinda strange. I've ordered a set of outer ends to hopefully get a smaller bodied one like the passenger side.
We will be moving the rack (along with the three link rear) to the primary car over the next couple weekends assuming we can get the tie rod issue solved. Carl's car will need a new roll cage and fuel cell before we can swap parts back and replace our current chassis with it.
Interesting. Not sure how the tie rod end got bigger on the driver side. The tie rods themselves are modified VW golf Mk1 pieces. There are definitely spares of the tie rods somewhere in the pile of stuff that came with the car. There are probably also new tie rod ends (almost guaranteed used ;-)), but maybe not.
Also interesting. One of my endurance co-drivers texted me a week ago and said he saw the car up in Portland. Probably the test day where the pic was taken.
Interesting. Not sure how the tie rod end got bigger on the driver side. The tie rods themselves are modified VW golf Mk1 pieces. There are definitely spares of the tie rods somewhere in the pile of stuff that came with the car. There are probably also new tie rod ends (almost guaranteed used ;-)), but maybe not.
Cheers,
Carl
Thankfully the replacement tie rods are cheap. I think like $12 each and more readily available than FB tie rods...
12-01-21, 06:21 PM
