rack and pinion 101
Posted: Dec 24, 2008 1:31 PM
OK, after numerous requests for info. on my RP conversion I decided to do a half assed attempt at a write up. I want to preface this by stating that I am NO engineer or fabrication whiz. I can't do math, have no geometry skills and am, in general, not the engineering type other than the backyard variety. Having said that, my approach to this mess was simple logic and a lot of trial and error. There's no doubt in my mind that things could have been done differently but this was an effort by your average "Joe" and if I can do it, anyone can. I did some research on this topic and didn't come up with much. I spoke with a few guys in CA that had "heard" of this having been done but was not able to make any connections. Given this, I went at it blind.
Searching for the rack to use was pretty easy. I had several e21 racks on the shelf so that was the logical choice. I despise the 4 turns lock to lock in my 323 and from the outset knew this would be an issue. I'd heard of the roundy round guys using steering quickeners and immediatly knew this would be the answer to the problem. The other problem with the e21 unit is that the e28 pump will more than likely blow the seals in the rack. With an e21 power rack being a pretty rare item, I chose to convert the e21 pump to fit the M30 and avoid any issues.
Frist off, modifiying the sub frame.
This was actually quite easy with an e21 rack. All I did was to weld some tabs to the backside of the subframe and the rack mouted right up.
Here's the only reference I had before I set out on this project. If it's your car I hope you don't mind the posting.
The idea was sound but I chose to do the mounts a bit sturdier. This is what I came up with.
Since this car is primarily for the track and the old steering shaft location was no longer useable, I moved the firewall opening a fair amount lower in the firewall. This allowed for a better angle of the steering shaft. Also, I mounted the rack at a downward angle so as to make the output shaft more in line with the steering shaft (if that makes any sense!)
I cannot say that this method will work with the steering shaft in its OEM position (as it exits the firewall) with an e21 rack. I've since learned the 944 , e36, Pinto (yeah, Pinto) and several others might have more optimal angles. Regardless, it works fine for my application.
OK, this was all well and good until the car started going back together. It was then that I realized it was more than a little flawed and I needed to start over. With the suspension back in the car and having a look at where things were lining up, it became blatantly obvious that bump steer was going to be an issue.......and a big one at that.
Here's a pic with everything where it should be (approx). Note the extreme angle of the tie rod in relation to the lower control arm.
Here's approx where things would have been under full compression. This ain't gonna work!!
Several years ago on RF (prior to the exodus) I'd seen a writeup on bump steer issues with severly lowered cars. I recalled someone putting a spacer between the bottom of the strut tube and the steering arm plate. After a search I was not able to find anything like that on the market (since have found them) so I made some 1" thick alum. spacers. The results speak for themselves.
Here's at "rest", then under full compression. Better, but still not great.
This left me scratching my head. I bounced these pics off a few guys, most who said it might not be that big of a deal and to live with it. Something told me I could figure this out so I did something else for a few weeks and got back to it.
What I came up with was a complet re-think of the whole thing. Unfortunatly I got in the "groove" and didn't take any photos of this process but in short, I pulled the motor and remounted the rack as high as possible in the chassis. It now clears the oil pan by less than 1/4 inch. I also moved the rack back an inch further so as to lessen the fore/aft angle of the tie rods as they went from the rack to the steering arm. Given the rack is back a bit further I rotated the rack so the output shaft/steering shaft would still line up. This actually worked out better than before since the U joint takes a much less severe angle.
This was lot better but still not what it could be so I got creative. I came up with the plan to get rid of the ball joints, install some HD heim joints and attach them to the bottom of the steering arm. Bingo.
Excuse the poor pic, but you get the idea. The camera angle is poor but the tie rod/LCA is now parallel.
How I did that was pretty easy. I removed the tie rods from the steering rack and cut them off. I then took some 3/4" steel bars, hollowed them out and threaded each end.
.
This setup comes with a price. Given the heim joints are located where they are, a 17" rim must be used. 16's rub and I can't see any way a 15 will work. I'm using 17"'ers so it was no big deal. Since the car is lowered quite a bit, this might not be an issue if the 1" spacers are not used.
There are still questions to be answered. One is that the e21 323 is a much lighter car up front and this setup might not work. This is quite true but there is nothing on this car that doesn't need to be there. I'm guessing the weight to be similar to that of the 323 and am crossing my fingers there are no issues. The trial and error approach once again!
Secondly, the way it's set up now it's 2 turns lock to lock. This may be great for AutoX but cruising down the highway might be a problem. If so I'll install the other quickener. If that's still an issue it'll be back to the OEM e21 ratio. Thankfully it's easy to install/remove the quickener!
Well, I'm sure there's plenty left out but that's it in a nutshell. This is by no means the definative way of doing it and I'm sure a more talented person can come up with a better way. I've gone so far as to hire a master welder and fabricator to come over and go over everything with a critical eye. It's got his thumbs up so I'm pleased from that standpoint.
I hope this helps those who are thinking about doing it.
Searching for the rack to use was pretty easy. I had several e21 racks on the shelf so that was the logical choice. I despise the 4 turns lock to lock in my 323 and from the outset knew this would be an issue. I'd heard of the roundy round guys using steering quickeners and immediatly knew this would be the answer to the problem. The other problem with the e21 unit is that the e28 pump will more than likely blow the seals in the rack. With an e21 power rack being a pretty rare item, I chose to convert the e21 pump to fit the M30 and avoid any issues.
Frist off, modifiying the sub frame.
This was actually quite easy with an e21 rack. All I did was to weld some tabs to the backside of the subframe and the rack mouted right up.
Here's the only reference I had before I set out on this project. If it's your car I hope you don't mind the posting.
The idea was sound but I chose to do the mounts a bit sturdier. This is what I came up with.
Since this car is primarily for the track and the old steering shaft location was no longer useable, I moved the firewall opening a fair amount lower in the firewall. This allowed for a better angle of the steering shaft. Also, I mounted the rack at a downward angle so as to make the output shaft more in line with the steering shaft (if that makes any sense!)
I cannot say that this method will work with the steering shaft in its OEM position (as it exits the firewall) with an e21 rack. I've since learned the 944 , e36, Pinto (yeah, Pinto) and several others might have more optimal angles. Regardless, it works fine for my application.
OK, this was all well and good until the car started going back together. It was then that I realized it was more than a little flawed and I needed to start over. With the suspension back in the car and having a look at where things were lining up, it became blatantly obvious that bump steer was going to be an issue.......and a big one at that.
Here's a pic with everything where it should be (approx). Note the extreme angle of the tie rod in relation to the lower control arm.
Here's approx where things would have been under full compression. This ain't gonna work!!
Several years ago on RF (prior to the exodus) I'd seen a writeup on bump steer issues with severly lowered cars. I recalled someone putting a spacer between the bottom of the strut tube and the steering arm plate. After a search I was not able to find anything like that on the market (since have found them) so I made some 1" thick alum. spacers. The results speak for themselves.
Here's at "rest", then under full compression. Better, but still not great.
This left me scratching my head. I bounced these pics off a few guys, most who said it might not be that big of a deal and to live with it. Something told me I could figure this out so I did something else for a few weeks and got back to it.
What I came up with was a complet re-think of the whole thing. Unfortunatly I got in the "groove" and didn't take any photos of this process but in short, I pulled the motor and remounted the rack as high as possible in the chassis. It now clears the oil pan by less than 1/4 inch. I also moved the rack back an inch further so as to lessen the fore/aft angle of the tie rods as they went from the rack to the steering arm. Given the rack is back a bit further I rotated the rack so the output shaft/steering shaft would still line up. This actually worked out better than before since the U joint takes a much less severe angle.
This was lot better but still not what it could be so I got creative. I came up with the plan to get rid of the ball joints, install some HD heim joints and attach them to the bottom of the steering arm. Bingo.
Excuse the poor pic, but you get the idea. The camera angle is poor but the tie rod/LCA is now parallel.
How I did that was pretty easy. I removed the tie rods from the steering rack and cut them off. I then took some 3/4" steel bars, hollowed them out and threaded each end.
. This setup comes with a price. Given the heim joints are located where they are, a 17" rim must be used. 16's rub and I can't see any way a 15 will work. I'm using 17"'ers so it was no big deal. Since the car is lowered quite a bit, this might not be an issue if the 1" spacers are not used.
There are still questions to be answered. One is that the e21 323 is a much lighter car up front and this setup might not work. This is quite true but there is nothing on this car that doesn't need to be there. I'm guessing the weight to be similar to that of the 323 and am crossing my fingers there are no issues. The trial and error approach once again!
Secondly, the way it's set up now it's 2 turns lock to lock. This may be great for AutoX but cruising down the highway might be a problem. If so I'll install the other quickener. If that's still an issue it'll be back to the OEM e21 ratio. Thankfully it's easy to install/remove the quickener!
Well, I'm sure there's plenty left out but that's it in a nutshell. This is by no means the definative way of doing it and I'm sure a more talented person can come up with a better way. I've gone so far as to hire a master welder and fabricator to come over and go over everything with a critical eye. It's got his thumbs up so I'm pleased from that standpoint.
I hope this helps those who are thinking about doing it.
