Rack and pinion conversion question - M2 build

[djm1968]

Hello,

I am deep into the planning an parts procuring stages of my M2 build. I am gather parts to rebuild the front suspension and steering. Decided that I'd really like to do a rack+pinion conversion.

I am wondering what rack to use? I have seen people use a rack from a 320i and an 323is -- any difference in these racks? I have a lead on a 320i rack for very cheap, but want to see what you folks think first. Also, have anyone tried converting to rack steering using a non-BMW rack? Some years back, when I was into vintage Mustangs, a company came out with a rack conversion supposedly based on a subaru rack...

Thanks,

DJM

[Caesar]

i am curious if it is any way to use a E36 steering rack in the 2002 .... !

[CamB]

E36 rack mounts in front of the axle, so you'd need to figure that out too.

I have had a Toyota rack put in mine. The rack is not superior (or inferior) to the e21 rack from what I can tell, and the Toyota rack was chosen since it is easier to find and wasn't expensive.

The devil is in the details - I have had the steering arms drilled (and crack tested) to move the tie rod attachment point further in (which quickens the ratio), and the rack is shortened and has limiters to make sure it doesn't try and turn the wheels too far.

I now have slightly under 3 turns lock to lock, and a very light wallet. I haven't driven it yet so I have no idea if its any good.

[djm1968]

Very interesting. What Toyota rack did you select? I am thinking I am going to simply head to the junk yard with tape measure and look for something that has similar track dimension to an 02.

Out of curiosity, approx. how much did this all cost you? I'd do most of the work myself, including shortening the arms. I was estimating that a rack conversion should not be significantly more than the cost of rebuilding a stock box/stock steering gear.

I'd certainly like to know how you conversion turns out in regards to feel, effort, etc. Keep us informed!

Thanks,

DJM

E36 rack mounts in front of the axle, so you'd need to figure that out too.

I have had a Toyota rack put in mine. The rack is not superior (or inferior) to the e21 rack from what I can tell, and the Toyota rack was chosen since it is easier to find and wasn't expensive.

The devil is in the details - I have had the steering arms drilled (and crack tested) to move the tie rod attachment point further in (which quickens the ratio), and the rack is shortened and has limiters to make sure it doesn't try and turn the wheels too far.

I now have slightly under 3 turns lock to lock, and a very light wallet. I haven't driven it yet so I have no idea if its any good.

[inkatouring]

Nick Vyse did a e21 rack into a RHD touring to fit his M2 conversation. See more details here: http://www.m2bmw.com/complete_spec.htm

[CamB]

I am not sure which Toyota rack - I'll try and find out. An early RWD one I think. Remember I said it's been modified fairly extensively.

I honestly don't know what it cost. Lots and lots (I had an overhung brake pedal assembly installed and the brakes converted at the same time and the bill was huge). Physically mounting the rack isn't that hard, and neither is modifying the steering arms (by the way the engineer preferred them to be redrilled rather than cut and welded). As I said, the rack needed shortening and limiting as well. The steering shaft needed cutting, welding and crack testing.

For the rack, rod ends (see pic), shortening the rack, modifying the rack ends and steering shaft, crack testing, etc was over US$500 (that was outwork), plus fabricating the rack mount and endless stuffing around ... lots of $$$ total. In my case its a race car (with a turbo - aiming for 250hp plus) and I'm trying not to take any shortcuts, so for instance there will be an hour or two of labour checking the bump steer and ackerman (sp?) angle, etc.

(there is more clearance than it looks between the wheel and the nut)

[NickVyse]

Nick Vyse did a e21 rack into a RHD touring to fit his M2 conversation.

I love an M2 conversation, but some people find it boring.

Any old rack that fits and is designed to mount behind the front axle should do the trick really. Remember some 6 cylinder e21's had power steering.

Another Aussie racing 02 used a Mazda rack.

If you're doing all the work yourself and mainly using scrap yard bits it's not going to cost you much. €100 got me shortened steering arms with precise geometry, but I've yet to fit them as the car's off the road. Just got myself a LHD e21 rack as I'm changing shell from a RHD to a LHD - the rack was on the high side at €150 - the bonus was it came attached to the rest of a 5 speed 318...

[djm1968]

CamB,

Great info. I am shooting for 225hp or so (to start!), also a track car -- I am into hillclimbs and, eventually, I'd like to hit a tarmac rally (there are a few left here in N. America). While I want to keep costs in-line, I am not willing to risk my safety -- I think your checking specs is quite prudent.

Interesting that your engineer suggested re-drilling rather than cut/weld -- make sense, especially for old parts.

Old toyotas, esp RWD, are rare here in the States, so I think I am going to look into subaru racks, failing that I'd go to an e21.

One last thought -- seems the racks often have rather slow steering ratios; any thoughts on using steering quickener like this:

http://www.howeracing.com/steering/Index-Quickener-Quickener.htm

Cheers,

DJM

I am not sure which Toyota rack - I'll try and find out. An early RWD one I think. Remember I said it's been modified fairly extensively.

I honestly don't know what it cost. Lots and lots (I had an overhung brake pedal assembly installed and the brakes converted at the same time and the bill was huge). Physically mounting the rack isn't that hard, and neither is modifying the steering arms (by the way the engineer preferred them to be redrilled rather than cut and welded). As I said, the rack needed shortening and limiting as well. The steering shaft needed cutting, welding and crack testing.

For the rack, rod ends (see pic), shortening the rack, modifying the rack ends and steering shaft, crack testing, etc was over US$500 (that was outwork), plus fabricating the rack mount and endless stuffing around ... lots of $$$ total. In my case its a race car (with a turbo - aiming for 250hp plus) and I'm trying not to take any shortcuts, so for instance there will be an hour or two of labour checking the bump steer and ackerman (sp?) angle, etc.

(there is more clearance than it looks between the wheel and the nut)

[djm1968]

Nick,

Hard to imagine an M2 being boring, IMO. :-)

I do plan to perform most of the swap myself (if I go that route), but I'd certainly have the parts checked for cracks, etc. My big worry is more to do with messing up the steering geometry, rather than building something that will fail. So far, I have not found a resource that lists the full specs/details of a rack conversion, so it seems there is more to research.

Cheers,

DJM

Nick Vyse did a e21 rack into a RHD touring to fit his M2 conversation.

I love an M2 conversation, but some people find it boring.

Any old rack that fits and is designed to mount behind the front axle should do the trick really. Remember some 6 cylinder e21's had power steering.

Another Aussie racing 02 used a Mazda rack.

If you're doing all the work yourself and mainly using scrap yard bits it's not going to cost you much. €100 got me shortened steering arms with precise geometry, but I've yet to fit them as the car's off the road. Just got myself a LHD e21 rack as I'm changing shell from a RHD to a LHD - the rack was on the high side at €150 - the bonus was it came attached to the rest of a 5 speed 318...

[NickVyse]

Nick,

Hard to imagine an M2 being boring, IMO. :-)

I do plan to perform most of the swap myself (if I go that route), but I'd certainly have the parts checked for cracks, etc. My big worry is more to do with messing up the steering geometry, rather than building something that will fail. So far, I have not found a resource that lists the full specs/details of a rack conversion, so it seems there is more to research.

Cheers,

DJM

Nick Vyse did a e21 rack into a RHD touring to fit his M2 conversation.

yep - there's no definitive way on this - have you seen Moespeeds work? Some great stuff - have a search here if you haven't already.

[CamB]

One last thought -- seems the racks often have rather slow steering ratios; any thoughts on using steering quickener like this:

http://www.howeracing.com/steering/Index-Quickener-Quickener.htm

Cheers,

DJM

If you use (for example) an e21 rack with 2002 arms, the ratio of wheel turns is bad AND the lock is bad. Putting a quickener on fixes only the ratio - it won't fix the lock.

That is why the arms need to be shortened.

[djm1968]

Nick,

Hard to imagine an M2 being boring, IMO. :-)

I do plan to perform most of the swap myself (if I go that route), but I'd certainly have the parts checked for cracks, etc. My big worry is more to do with messing up the steering geometry, rather than building something that will fail. So far, I have not found a resource that lists the full specs/details of a rack conversion, so it seems there is more to research.

Cheers,

DJM

Nick Vyse did a e21 rack into a RHD touring to fit his M2 conversation.

yep - there's no definitive way on this - have you seen Moespeeds work? Some great stuff - have a search here if you haven't already.

Yes, I've seem Mospeeds work on www.m2bmw.com. Does he frequent these forums?

Cheers,

DJM

[djm1968]

One last thought -- seems the racks often have rather slow steering ratios; any thoughts on using steering quickener like this:

http://www.howeracing.com/steering/Index-Quickener-Quickener.htm

Cheers,

DJM

If you use (for example) an e21 rack with 2002 arms, the ratio of wheel turns is bad AND the lock is bad. Putting a quickener on fixes only the ratio - it won't fix the lock.

That is why the arms need to be shortened.

Sorry, I should have been more clear with my question: yes, the 02 steering arms must be shortened to 130mm to match the e21 rack. What I was meaning to ask is along these lines:

quick ratio racks seem to be impossible/difficult to find. Some of us who perform rack conversions also want a much faster steering ratio -- I was just curious if any of the "steering geeks" on the forum had experience with the quickeners.

Cheers,

DJM

[NickVyse]

One last thought -- seems the racks often have rather slow steering ratios; any thoughts on using steering quickener like this:

http://www.howeracing.com/steering/Index-Quickener-Quickener.htm

Cheers,

DJM

If you use (for example) an e21 rack with 2002 arms, the ratio of wheel turns is bad AND the lock is bad. Putting a quickener on fixes only the ratio - it won't fix the lock.

That is why the arms need to be shortened.

Sorry, I should have been more clear with my question: yes, the 02 steering arms must be shortened to 130mm to match the e21 rack. What I was meaning to ask is along these lines:

quick ratio racks seem to be impossible/difficult to find. Some of us who perform rack conversions also want a much faster steering ratio -- I was just curious if any of the "steering geeks" on the forum had experience with the quickeners.

Cheers,

DJM

A/ yes, Moespeed is here, and as stated there's much more info on his set-up f you search the FAQ than there is on my web site.

B/ Also do a search on steering quickeners here - it's been done. There was also a guy in the UK who made a close ratio set of gears for an e21 rack. If you're interested email me direct and I'll see if I can dig out his address.

Nick