m3 steering rack upgrade

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dr al
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m3 steering rack upgrade

Post by dr al » Thu Jun 05, 2014 8:35 pm

Swapped my 2006 pre-fl 130i's steering rack across to an e90 M3 unit a couple of weeks ago.

I got a good deal from a guy in london on ebay. £200 for the rack, and an M3 front ARB complete with bushings and clamps. Plus postage

This is all just a description of what i did.
Follow this on your own car at your own risk, i take no responsibility for anything!)

-Jack up the car, and put it on axle stands
-Remove undertray.
-Undo nuts holding track rod ends to the hubs. If you're lucky the ball joints will pop out (mine did despite 90K miles on the clock). If you're unlucky you'll need a pickle fork or a ball joint extractor.
-Remove as much ATF from the power steering reservoir as you can (if you're sensible - i didn't bother)
-Undo the two banjo bolts from the stem part of the steering rack. Have a tray and a load of newspaper in place, the ATF goes everywhere, and there's loads of it to come out (well, almost a litre)
-Move the steering left and right a dozen times to "pump" out the remaining fluid.
-Turn the steering until you can see the clamp bolt where the column meets the rack. Undo and remove the bolt (it locks into a groove and hole on the rack so must be removed)
-Undo the hose supports at the front of the steering rack (which hold the power steering hydraulic lines in place).
-Undo the two large ASA bolts (you'll need a reverse torx socket for this - i forget the size. My whole set only cost £6 from ebay - holding the nuts above while you do.
-Wiggle, slide and pull the rack forwards out of the front of the subframe where it sits - The steering column disconnects itself while you do this, try not to let it fall down and bash things in the engine bay.
-Drop the rack out of the car.

Here's a couple of pics of the two racks together
Top one is the M3 one
Image

Closer one is the M3 one - you can see the servotronic solenoid sticking out the side
Image

As you can see the two racks are identical apart from a couple of things.

The heat shields are different. I kept the M3 one on, cos it was shinier. It fits just fine, but makes it an absolute hound to get the steering column pinch bolt back in, so probably best put the e87 one back on.

The hard-wired pipes which are part of the rack are slightly different. The front one comes round the left (as you look at it from the front) side of the front bracket (where the hose guides clamp), rather than over the top of the left bracket on the e87 rack. You can see it in the first pic.
When you put it all back together this pipe gets in the way of the pipe bracket. I had to dremmel off part of the left hand bracket (leaving one hose unsupported at that side - the other hose clamps on as normal). As both hoses are clamped on the right side there's no play in the hose where i removed the part of the clamp, and no chance of rattling. I think it'll be ok.
You could, however, swap over the metal hose from your old rack to replace the bit on the M3 one. i'm sure that'd work fine, but i wasn't brave enough.

It's a pain in the butt to get the new rack into place if you're working on your own, but i managed in the end.
You need to get it nearly in place in it's mounting point then get the steering column lined up and on, then waggle it into place.

BMW TIS and realoem.com are adamant that you have to replace the ASA bolts and nuts that hold the rack in place. I did. Bolts 32106773068, nuts 31356757707

So i got it back in place, bolted in with new bolts (56Nm + 90deg) , modified the hose guide bracket, and bolted the two guides back onto the brackets on the front of the rack (8Nm).
At this point i found that the steering column didn't come right down flush with the top of the rack, there was a 4mm gap which would mean that the pinch bolt wouldn't have a chance of getting into place.

Panic time.

Inside the car, in the drivers footwell (seen once you've removed the panel above the pedals) is a telescoping part of the steering column right near where it goes into a big rubber sleeve.
It was clear from where the rubber had been touching the steering rack that this had telescoped back up a few mm, and was causing my problems. I didn't get any photos of this i'm afraid.

I got a mate to bang on this telescoping part with a rubber mallet and a bit of wood to gently get it extended back out, while i waggled things where the column meets the rack. We got it back into the right place in about a minute. Pinch bolt went in ( i had to get right in under the car to get this in, as the M3 heat shield stopped me getting in from above - the e87 heat shield didn't have this problem) (21Nm).

Replaced the gasket washers on the banjo bolts - one on the rack side, on on the bolt-head side for each bolt - part nos 9906463 and 9906464 - 2 of each.
and torqued them up - very little! Pressure line - M14 30Nm, Return line - M16 35Nm

Fill up the reservoir with ATF (some systems need a different fluid, and say so on the power steering reservoir lid) Any Dex3 fluid will do fine from what i read.

The online guides for changing the power steering fluid (like this one - http://www.m3forum.net/m3forum/showthread.php?t=140947 ) suggest that you move the wheel at this point to draw fluid into the system. This did nothing on my car. I had to turn on the engine and move the wheel back and forth. It made a hideous noise at first, and frothed up the ATF like cappuccino, but that settled after a few seconds, then it was fine.

-Bolt the track rod ends back to the hubs (replacing the bolts if you believe BMW - 33306787062) - 165Nm
-Put the undertray back on
-Do your allignment.

I changed all 4 front suspension arms to M3 ones at the same time as changing the rack, and even with this extra track, my M3 track rod ends were less than half a turn from the end of their adjustment (they could barely go any more toed in). The M3 and e87 have different track rods (M3 significantly longer - as you can see from the pics) , but i just got away with it!. I don't know if i could have got this to align properly if i hadn't had the M3 control arms.

I do my own alignment DIY in a similar way to this http://forums.pelicanparts.com/porsche- ... iyers.html.
It's very accurate, and (as long as you can do basic trig) very easy.
My laser spirit level was £25 from screwfix, and if you set things up sensibly, you can get any potential errors from the laser to cancel eachother out.

So...

The rack is very heavy compared to the stock e87 one, but only below 30-40mph.
It's MUCH quicker, and totally transforms the car when you drive it hard! Suddenly it actually drives like a sports car.

The heaviness is because the M3 has servotronic which was not an option on the e87 unless you had active steering.
With the servotronic unplugged, the rack defaults to minimum assist, which is perfect above 40mph, but a bit heavy below. It's really quite like driving the unassisted rack on my old lotus.
The servotronic takes a PWM (pulse width modulation) signal at 9v, so theoretically it should be fairly easy to hit maplin and sort out a simple module to allow you to dial in as much assistance as you want.
This had been my plan, but after just 2 weeks with the new rack i barely notice the heaviness (it seems less every day), so i doubt i'll bother.

Overall i'm extremely happy with this mod. It's completely transformed the car. It's about a month before i have more time off work to do my rear M3 arms, subframe bushings, ARB, Quaife Diff and 135i brakes. I can't wait to thrash it with all that done.

Alan.

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rob180bhp
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Re: m3 steering rack upgrade

Post by rob180bhp » Thu Jun 05, 2014 8:43 pm

Nice write up......

My future mod

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Griff500
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Re: m3 steering rack upgrade

Post by Griff500 » Tue Jun 10, 2014 4:56 pm

Brilliant post. First DIY for this online anywhere as far as I can see. I have the rack ready to go on my 135i shortly.

If you do manage to get the servotronic working please report back, I think this feature is worthwhile and makes the 1M feel very nimble at low speed.

Cheers

dr al
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Re: m3 steering rack upgrade

Post by dr al » Tue Jun 10, 2014 9:55 pm

Thanks.

Some of the guys who've put M5 racks into their 540i cars have managed to retrofit proper BMW servotronic control by wiring the solenoid into the appropriate module (i can't remember which one it is but it's easy enough to find on google) but that works because servotronic was an option on the 540.
On our cars, only the active steering cars have servotronic, so i'm not sure we'll have the hardware / software options to get it sorted.

Having said that, getting a feed of the car's speed from the OBD connector is pretty easy, so using that to create a diy speed sensitive control module would be possible.
The M5 guys who've looked at the output say that the power to the solenoid is all off by the time the speed's up to 35 or 40 or so, so it's just a boost below that that's needed.
It's all just a matter of finding the time to play with it all!


If i do get round to it i'll definitely post, but i wouldn't hold your breath!

damianz
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Re: m3 steering rack upgrade

Post by damianz » Sat Jul 05, 2014 4:31 pm

Also have done it to my car, easy swap (for some people :roll: )

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Re: m3 steering rack upgrade

Post by rob180bhp » Sat Jul 05, 2014 4:35 pm

Any idea of rack part numbers

I want to start looking for one

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Re: m3 steering rack upgrade

Post by rob180bhp » Sat Jul 05, 2014 5:07 pm

There is lots of pwm controllers kits on eBay I'm sure they can be adapted to operate the valve on the rack

Have a switch or knob on dash board for parking or low speed mode
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Re: m3 steering rack upgrade

Post by rob180bhp » Mon Jul 14, 2014 7:00 pm

Im looking for a rack now

A few questions

have you kept the 135 connecting rod between rack and column?

So i need a rack and metal pipes on it and thats it all the rest are 135 parts
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Re: m3 steering rack upgrade

Post by rob180bhp » Mon Jul 14, 2014 7:13 pm

Will my steering arms and track rods ends swap accros go an m3 rack

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Re: m3 steering rack upgrade

Post by damianz » Mon Jul 14, 2014 10:48 pm

rob180bhp wrote:Will my steering arms and track rods ends swap accros go an m3 rack

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yep

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Re: m3 steering rack upgrade

Post by rob180bhp » Mon Jul 14, 2014 10:49 pm

I thought they might do, that's great news as they are new, well they were a few months ago lol

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dr al
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Re: m3 steering rack upgrade

Post by dr al » Tue Jul 15, 2014 5:34 pm

rob180bhp wrote:Will my steering arms and track rods ends swap accros go an m3 rack

........................................
2008-135i jb4 +mods
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What do you mean by steering arms?
The track rod ends swap straight across, but i believe that the track rods themselves attach to the rack in a different way on the M3 (this is second hand from other forums, not my personal knowledge)


Also, to update, i changed my geometry settings, cutting the front toe down to just 2minutes toe in each side (instead of 5) and it makes the rack much lighter.
I think i'm getting less and less likely to bother messing with the servotronic.

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Re: m3 steering rack upgrade

Post by rob180bhp » Tue Jul 15, 2014 8:12 pm

Yes I mean the part between the rack and the track rod ends

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Re: m3 steering rack upgrade

Post by rob180bhp » Sun Jul 20, 2014 9:46 pm

Was there a master spline on the steering rack ?
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dr al
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Re: m3 steering rack upgrade

Post by dr al » Mon Jul 21, 2014 9:36 pm

rob180bhp wrote:Was there a master spline on the steering rack ?
I'm afraid i have no idea what that is!
The steering wheel end was identical, and the track rod ends were identical.
Apart from replacing a rubber boot i didn't really venture into the middle bit!

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