Jun 17, 2019 update to the BMW 318is project car

Project BMW 318is: Replacing the Steering Rack

While we had no real issues with the steering in our E30, we had heard about various steering racks being used to quicken the steering ratio.

We were going to start with the stock rack and see how we liked it. We liked it fine, until it blew out, just minutes after finishing the car. It was one of the few chassis parts we did not replace while restoring the car. Initially, we just cleaned our original steering rack and put new tie rod ends and boots on it. Murphy’s Law caught up with us rather quickly.

The stock E30 rack is said to be 4.0 turns lock to lock. An E36 steering rack from an M car is said to be 3.5 turns and the Z3 steering rack is a razor quick 2.7 turns lock to lock.

FCP Euro now makes a kit to install a Z3 rack into an E30. This kit includes the spacers and different power steering hoses you will need, as the hoses are mounted differently on the Z3 rack.

Installation was fairly straight forward but will still take a bit of engineering to get a few details worked out.

We never really considered E30 BMW steering to be slow, but once the Z3 rack is installed, you quickly realize what you’ve been missing. While some have said the Z3 rack makes the E30 twitchy, we haven’t found that to be true at all in the three thousand miles of driving we done thus far, including two trips to VIR where we ran the full course.

There is more steering effort with the quicker rack and parking and moving around tight places is now noticeable, but not objectionable.

FCP Euro’s Quick steering rack kit comes with just about everything you need to make the swap. Notice how the power steering hose mounts differently on the Z3 steering rack.

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Ransom
Ransom PowerDork
6/17/19 5:18 p.m.

This was one of the best things I did to my E30, and would be one of the first things I'd do if I had another. Preferably simultaneous with an engine swap for access to the rack... The kit would've been handy.

Brian_13
Brian_13 New Reader
6/17/19 5:21 p.m.

2.7 turns lock-to-lock is "razor quick"? Aside from the strange expression (razors are sharp, lightning and other things are quick), this doesn't seem exceptional; maybe it is for a BMW.

Steering quickness isn't just a matter of turns lock-to-lock anyway. If comparing to other vehicles, rack travel and steering arm length also contribute to the overall steering ratio, and the wheelbase determines what ratio is effectively quick. So, with the 2.7 turn rack, is the result Corvette-quick ('Vettes have had less than 2.7 turns for decades) or Spitfire-quick, for instance?

irish44j
irish44j MegaDork
6/17/19 8:52 p.m.

You need to be more specific if you're going to throw information out there for readers:

e36 racks = all have the same variable/progressive ratio, except the '95 M3, which is actually slower. Just that year of the M3. A few M3 racks have slightly less turn lock to lock (like a 1/4") due to need for wheel well/frame clearance for wider tires. But same exact rate. 

z3 1.9 rack = same as the e36 rack (possibly a bit shorter lock-to-lock due to wheel well/frame clearances)

The only one that's quicker (and presumably the one you have) is the Z3 2.7 rack, which is the same "main" ratio but is fully linear, so it's quicker in the center, giving an quicker overall ratio. It has the same overall travel as the e36 racks, but in less turns due to the linear center. 

All of these I've used, and measured myself and compared. There's a lot of misinformation on the internet so I checked myself.

ANyhow, may want to edit to specify that it's the Z3 2.7 rack that is quicker, so readers dont' go pick up 1.9 Z3 racks and find them exactly the same as any e36....

 

 

Ransom
Ransom PowerDork
6/18/19 12:20 a.m.

In reply to irish44j :

That's awesome info. I couldn't tell you which Z3 rack I had, nor can I tell you whether I could have told you at the time... I'm guessing 2.7 Z3 given that it seemed like a huge improvement.

I suppose at least if someone gets an E36/1.9 Z3 rack it's still quicker than the E30 unit. While there are lots of things that improve an E30, the ponderously slow steering was the first thing that jumped out and really bothered me about the stock car.

irish44j
irish44j MegaDork
6/18/19 7:40 p.m.
Ransom said:

In reply to irish44j :

That's awesome info. I couldn't tell you which Z3 rack I had, nor can I tell you whether I could have told you at the time... I'm guessing 2.7 Z3 given that it seemed like a huge improvement.

I suppose at least if someone gets an E36/1.9 Z3 rack it's still quicker than the E30 unit. While there are lots of things that improve an E30, the ponderously slow steering was the first thing that jumped out and really bothered me about the stock car.

Oh yeah, I had the e30 rack, then a e36 rack, and now the z3 2.7. The 2.7 rack is noticeably quicker off-center (which is important for rallycross precision). For track/street driving not sure if the extra cost/effort to find that one would be worth it over the standard e36, to be honest. 

mike_grassroots
mike_grassroots New Reader
6/19/19 6:36 a.m.

Does the firewall still need to be notched for airbag equipped E30s?  Or does the FCP kit no longer require the firewall modification?  Link to the FCP kit please!  I couldn't find it on their website.

Tim Suddard
Tim Suddard Publisher
6/19/19 1:39 p.m.

irish44j. Thanks for the clarification on the rack. And let me get a link from FCP Euro. I don't believe we notched the firewall, but let me check again, as it was a while ago since we did this.

mike_grassroots
mike_grassroots New Reader
6/19/19 8:08 p.m.

In reply to Tim Suddard :

Thanks!  I replaced the rack on my 318is a few years ago with a stock refurb.  Still works great, but I'd love something with a better ratio without having to notch the firewall.

I've said it before, but I absolutely love this build.  You guys really knocked it out of the park.  I've picked up a bunch of useful information for my project and I'm looking forward to how yours compares to the E30 M3 at VIR.

stuart in mn
stuart in mn MegaDork
6/19/19 9:33 p.m.

I don't suppose the internals from the Z3 rack can be swapped into the e30 housing?  I was thinking this may be a way to get the quicker steering without having to use an adapter kit.

irish44j
irish44j MegaDork
6/19/19 10:14 p.m.
stuart in mn said:

I don't suppose the internals from the Z3 rack can be swapped into the e30 housing?  I was thinking this may be a way to get the quicker steering without having to use an adapter kit.

I don't know the answer to your question, but having disassembled an e30 steering rack and reassembled it......just doing the adaptors is way less work. And on a non-airbag e30 it's actually pretty easy. 

Tim Suddard
Tim Suddard Publisher
6/20/19 8:39 a.m.

I checked with FCP Euro and sadly the Z3 rack is now on back order, so there is no link to order the kit. And we did not have to notch the firewall to do this installation.

Daeldalus
Daeldalus Reader
6/20/19 9:02 a.m.

The standard e36 rack and pinion is a 3.2 turn to lock ratio.

 

I installed one on my swapped e30. It has been really nice as a daily driver rack.

 

Also if anyone us looking for a z3 rack and pinion. Give Rack Doctor a call they have all the knowledges when it comes to racks. Prices aint bad either.

mike_grassroots
mike_grassroots New Reader
6/20/19 10:54 a.m.

In reply to Tim Suddard :

That is excellent news (that you didn't have to notch the firewall)!  I'll keep an eye out for when FCP restocks as the only thing that's been holding me back from doing this is the firewall modification.  Thanks so much for checking and following up!

Tim Suddard
Tim Suddard Publisher
6/20/19 12:16 p.m.

And I just got this back from Gareth Foley, who sells this stuff at FCP Euro and presumably was looking at part numbers when he sent it:

All Z3 non M variants share the same rack (1.9, 2.5, 2.8, 3.0, Coupe/Roadster). This is the quick linear ratio rack (~2.7 turns lock to lock). The Z3M variants share the same rack as the E36 models (with the exception of the 1995 M3 rack which is unique).

So while not trying to be a troll, Irish44J, I am not sure you are correct about some Z3 racks being unique.

 

Paynef
Paynef
7/29/19 1:39 p.m.

Can you advise us of the cost of the power steering kit and also please provide a part number.

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