I figured I should post here about what I have been working on since I am sure there are members in this board who would be interested in this or might be able to provide some good insight and ideas. Lately I have been stuck on doing a rack and pinion swap to my 95 525i since this needs to be the ultimate driving machine and a steering box does not cut it. I am going R&P for other reasons, but I would still prefer the feel of it anyways. Before I dive into my current project I will preface this by saying that this rack and pinion project does coincide with an LS swap so I in theory have a bit more freedom to alter things a stock car may otherwise not be able to. However with the route I have taken, I do believe it is possible that my planned setup may work on a stock E34 .
First thing was to determine which rack to use. Being a rear steer, it really limits the racks I can choose. I found a few racks that have the same inner tie rod pivot points at about 24" . There are a lot of GM racks that meet that criteria, Cavaliers, Sunfires, GTOs, LeSabers, etc. I did notice a lot of the GM racks shared a lot of the same architecture. But the big issue with those is the transfer tubes come out the front where it would hit the subframe and go over the top of the tube, which I will explain why that is an issue in my next point. But ultimately I have decided to skip the GM racks and go with a MKIII Golf rack that is ZF built. The lines come out the back and also stay low so no overhead clearance issues supposedly. Also when it comes to the steering ratio, the GM racks were all about 2-3/4 turns lock to lock and the VW rack was a tad under 3-1/4 turns. The linear travel of the stock center link was about 6-1/4" , the GM racks had about 5-1/4" of linear travel, and the VW rack has 5-1/2" of travel. So there will be a slight reduction in turning radius, less so with the VW rack. Not sure by how much however.
Picture below. Stock center link, mid 2000s LeSabre, 2001 Cavalier
Picture below, Golf Rack
Getting the geometry correct is going to be the biggest obstacle to overcome. I started by measuring the stock center link location. I measured it from some parts of the frame to the center points. The easy part is how far back to set it, the difficult dimension to keep will be the height. The stock center link dips down below the oil pan and comes back up towards the outside. Putting the rack in the exact location it needs to be will be putting it in the oil pan. This is where that overhead clearance issues arised with the GM racks. The closest I got was 1" below the stock location and that was fairly close to the oil pan and I removed the transfer lines to get it there.
I tried making new lines that were going to be routed to go under the rack but I can easily see an issue where they might get busted on a bad road since it does sit fairly low, and they use some weird fittings that I cannot find for sale.. The mounts on a horizontal mount rack will end up sticking below the sub frame making a very crucial part of the safe operation of this vehicle vulnerable. Not good.
The GTO rack has a vertical mount so it would be better and the lines get routed below the rack not on top but the lines look like they would stick out more than I feel comfortable with. That is why I decided to go with the VW rack. The lines come out the back and do not go above or below the tube so it would allow me a little more flexibility to get it in position. I have not tried putting the VW rack up yet but I will play around with it this weekend.
I doubt that I will make up the 1" so that brings me to where I am currently pondering. I am thinking of flipping the tie rod ends around to make up the difference. I know it would be better to have all the pivots (control arms, tie rods, etc) on the same plane but I do not see that happening. I am thinking of drilling a press fit hole through the tapered hole in the steering arms and making a separate bushing with the tapered hole so I can swap it around as I experiment. I do potentially see an issue with flipping the rod end. It almost looks as if it could potentially contact the wheel if it was fat enough.
Tie rods will be easy I hope. I am hoping some kind of off the shelf inners work, but I can order a custom set to certain dimension if needed for about $45 a piece. For the outer I need to figure out if the E34 is a 7 degree or 10 degree taper for the cone pin. Anyone know what it is? Steering linkage, I don't know but I am not too worried about that. I will get there when I get there. So that is where I am at, hopefully this will prove out and benefit us all. I know it has been done before but all the old threads the pictures are gone, the threads just died, or was very vague. I hope I can provide as much info to help anyone else out wanting to do this. I will continue to update as I progress with this and hopefully get this set up right.
95 E34 553i6 LS TR6060 Project
93 E34 525iA Beater with no heaterVANOS kicked in yo!
I may use a UK version E39 rack, flipped over.
Black on Black 740i - 10/92 build date, 225,000 miles.
Delphin on Cherry 533i - 4/84 build date, 136,000 miles
Black on Black 328i - 3/96 build date, 185,000 miles - Sold
2008 Porsche Cayenne GTS
95 E34 553i6 LS TR6060 Project
93 E34 525iA Beater with no heaterVANOS kicked in yo!
I will say this once and then STFU.
WHY has nobody tried simply attaching an E39 subframe? The geometry is already worked out, screwing one into place cannot be that difficult.
Over and out
If you can leave two black stripes from the exit of one corner to the braking zone of the next, you have enough horsepower. - Mark Donohue
I think it would be a great idea but I do have concerns over that. I tried looking into that but not a lot of info out there on that and I am already too invested to mounting this LS to the E34 frame that I cannot just throw it out that easily, but that is my personal problem. The GTO front sump oil pans are not cheap, I do not want to design more mounts for a different subframe and I got the F30 calipers to work on the E34 knuckle.
Another potential issue is the geometry when it comes to the strut. The E39 strut could be wildly dofferent than the E34 and a combo of E34 strut angle with E39 control arm geomotry could really screw woth the roll center in a negitive way. I do not think it would mess woth bumpsteer that much however. Again, I do not know how similar they are so it might not change at all for all I know.
Next issue is converting the knuckle to front steer. So either modify the E34 knuckle to be front steer, figure out how to mount E39 struts to the E34 body, or figure out how to make an E39 spindle bolt to E34 struts.
But again these could be non-issues beyond just mounting the subframe to the E34, I just simply do not know for sure.
95 E34 553i6 LS TR6060 Project
93 E34 525iA Beater with no heaterVANOS kicked in yo!
I swapped a caviler rack into mine for oil pan clearance. I had to mount mine a bit lower and had to do some work on the spindles to get the bump steer reasonable. I used an H2 pan and wish I had gone GTO. I am currently swapping to the Holly pan to get a little better sump clearance after the mishap.
Last edited by flynfrog; 09-13-2018 at 07:41 PM.
Here is my rack mount. sorry for the photobucket links
95 E34 553i6 LS TR6060 Project
93 E34 525iA Beater with no heaterVANOS kicked in yo!
How about the bump steer correction plates sold by AKG?
95 E34 553i6 LS TR6060 Project
93 E34 525iA Beater with no heaterVANOS kicked in yo!
In my opinion its basically a waste of effort.
Every vehicle is an assembly of packaging compromises, taking the compromises from one chassis and adapting them to another just compounds the issues. The geometry is really fairly simple.
I've had a rack setup in my e34 for 6 years now, and have a new revised version in a Alex's ^^ car for 3 years. It really changes the way these cars drive.
Shoot me a message, I don't forum too much these days. Looks like you are semi local too.
link to e30pickuptruck build thread
^driven coast to coast
First I hear of the E39 subframe idea. That would imply E39 control arms and struts, which are aluminum, which alone is a worthwhile upgrade. I'd be very interested to see what it took to work.
Depending on engineering resources available, I'd look into offset inner tierod ends, where the ball mounts higher than the rack, mimicking the E34 center link design.
Last edited by moroza; 09-14-2018 at 02:47 PM.
You are quite a bit higher up than I am. Wish I would have gone GTO pan. Initaly I got some rod ends off of a fiero I think. I think these are it. https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
I didnt like the bump steer so I drilled through the taped and went to heim joints. The issue will run into is that the GM rack is an oddball thread. You might try to the Fiero rod ends first though.
I think its a M14 1.5
I got my parts from
this place https://www.ebay.co.uk/usr/mcgillmot...p2047675.l2559
The attachment I hadn't tightened everything up yet. So they don't sit that low with that much bending on the bolt. I got good rated bolts from mcmaster. I also considered cutting and welding the spindle but I was concerned about keeping everything straight. I haven't really had any issues with the current setup. I do seem to get a weird roll steer at low angles and high body roll (freeway curves). I think a stiffer ARB will take care of this. Speaking of that you will probably run into an issue of the ARB wanting to occuppy the same place as your slightly lower steering. I just cut and extended the linkages about an inch. This probably lowered my roll stiffness but I wanted to do burnouts.
Sorry if this is somewhat brain dumpy but if you have any questions and I dont log in my email is my username at gmail
Good luck on the project.
I also forgot the horn grounds through the steering shaft so it might not work depending on what you end up with to make the shaft work.
Still working on this. I got a real asinine plan for the tie rods that involve a Honda Accord inners, stock outers, and some 7075 Aluminum. I got the subframe out after many hammer blows so I could mock things up even better. So I got some mounts drawn up that will be welded to the sub frame made out of 1-1/2 square tubing and some metal strips. I just bought a new AC/DC TIG welder so I am looking forward to doing this.
The amount I have the rack dropped compared to the center link allowed me to just lip over the steering arm and it will theoretically line up perfectly.
During my measurements the control arm pivot points chassis side are about 25" and 26.5" and it seems all pivot points on the knuckle are inline. It seems like there is built in bump steer from the factory given the center link pivots do not fall within the plane of the control arm pivots. I am not sure how much bump steer there is from the factory so I might just bolt all the stuff back together and find out to verify my theory. If I am correct, I will need to push the rack and pinion pivots out to abut 25-1/2" to 26"Also, I noticed on the sub frame where the control arms mount. There are 2 holes in the tabs, is the outboard hole there for no reason or is it a way from the factory to change the geometry?
95 E34 553i6 LS TR6060 Project
93 E34 525iA Beater with no heaterVANOS kicked in yo!
95 E34 553i6 LS TR6060 Project
93 E34 525iA Beater with no heaterVANOS kicked in yo!
Not to go too off-topic, but does an E32 thrust arm crossmember also share geometry (hole-to-hole distance... also important... ) with the E34? I wonder about swapping to an early rubber-mounted 750iL crossmember for extra NVH reduction.
Welded knuckles seem spooky. Though not as bad as what's in post 15.
Agreed and they will not be permanent, though this was not welded using your typical at home welder. It was welded with a 400 amp industrial welder. They are welded upsidown only for test fitting all the stuff. I will be making a whole new lower knuckle from scratch based on the new locations if all works out.
95 E34 553i6 LS TR6060 Project
93 E34 525iA Beater with no heaterVANOS kicked in yo!
Was finally able to get back at this project. Been hunkering down paying off all my debts years in advance so I should have a little more freedom to put towards this. I think I have a great start on this.
I was able to make some mounts for it and I am trading welding work from a co-worker for powder coating work. So for now it is just tacked. I am going to incorporate the rack and pinion mounts with the LS mounts since I need to redesign those. The oil pain will hit the R&P with the old mounts I made.
I made a quick concept of the tie rod which utilizes a 98 V6 Accord inner tie rod and a stock E34 outer tie rod with the LH thread. The connector is made of 7075 Aluminum and I think for the real pieceI will enlarge at the ends of where the threads are and have it taper off towards the middle to clear the control arm. As is it did not touch the control arm at any position around it's approximate real world suspension travel, but it got REAL close in some areas.
I tried my best to test for bump steer. This is where I could use some opinions on the results. The stock E34 wheel center to fender height it 15" (at least on my stock 93). I will probably lower the car with a set of Eibach springs I got so I set the wheel center to fender at 14" as my base. Below is my setup. I set the square at a 90 degree angle, parallel with the lower caliper mounting tab. I marked a spot on the tab and where it was in relation to the square which was at the 14" mark. I marked 2 more spots at 1" intervals above and below, so 4" total. I raised and lowered the suspension and observed the caliper mount move in relation to the square.
This is the video of the suspension travel. When the suspension is moved up (compressed, bump, whatever) 2" from the base line it hardly moves, but 2" below (droop, rebound, whatever you want to call it) it swings out a lot.
Can't figure out how to imbed video so heres the link.
https://www.youtube.com/watch?v=nICgq4ZjOlU
Last edited by XCRN; 07-03-2019 at 09:34 PM.
95 E34 553i6 LS TR6060 Project
93 E34 525iA Beater with no heaterVANOS kicked in yo!
95 E34 553i6 LS TR6060 Project
93 E34 525iA Beater with no heaterVANOS kicked in yo!
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