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E36 Steering Rack Question(s)

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I have been driving an 1997 E36 318i Motorsport sedan for 10 years. It's a made in SA car and it's a fantastic car.  I am the 2nd owner, the first owner brought it with him from SA. It has no modifications.  I recently bought a 1995 M3 sedan and am annoyed to discover that the steering ratio is lower than my 318i.  It's not a lot but enough that I noticed right away.  Any ideas on why this is?  The rack part numbers are different (on realoem.com).  Why would they be different?  

Thanks.

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Its well known the M3s have a shitty steering ratio. Get a purple tag rack in there.

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Agreed, purple tag makes a massive difference.

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BMW has done it to other models too.

The standard Z3 has a 2.7 turn to turn ratio, one of the fastest for a BMW.  The Z3M has a standard E36 rack, which is slower.  Why?  The interweb/forum logic is that the Standard Z3 is for normal road speeds.  Whereas the Z3M is likely to be track/performance driven and the fast rack at high speeds becomes dangerous.  Don't know if that's BMW's thinking or not.

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Whilst most of the above is true the most important thing hasn't been mentioned... the S50B30 M3 (~92-95) (i.e. your one) has a unique steering rack which is considered amongst the worst BMW has provided, it has no redeeming features, it's not used on any other vehicles.

Unless there's a ZA difference the rack in your 318 will be the same as in an M3 Evo which is still considered vague as best.

In ascending order of preference:

95 M3 Rack -> Standard E36 (inc. M3 Evo Rack) -> Retrofitted E46 Sport Rack ("purple tag") -> retrofitted Non-M Z3 Rack.

Some are progressive, some are linear, some have other changes, tons of info out there on the 'net. 

Edited by M3AN

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9 hours ago, NZ00Z3 said:

BMW has done it to other models too.

The standard Z3 has a 2.7 turn to turn ratio, one of the fastest for a BMW.  The Z3M has a standard E36 rack, which is slower.  Why?  The interweb/forum logic is that the Standard Z3 is for normal road speeds.  Whereas the Z3M is likely to be track/performance driven and the fast rack at high speeds becomes dangerous.  Don't know if that's BMW's thinking or not.

There is some 'logic' in this;  we  ran slower racks in touring cars  for two reasons:

  1. high speed racks are too twitchy ,
  2.  we ran less steering boost which robs power so the lower gearing makes the steering weight reasonable. 

Rack turns count is also mis-leading as the real measure is the rack extension per unit of turn - there should be a post where I gave the numbers from memory the range is from about 47mm / 90 degrees to  53 - the purple is about the same as the 2.7 because it has a longer stroke - the extra 0.3 ( 108 degrees) turns gives you more road wheel angle 

 

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I’ve heard the e46 zhp gold tag from the late model 330ci trumps all, but I think it was mostly made for the American market, so a rhd maybe hard to come by. I need to do some more research on that 

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11 hours ago, euroriffic said:

I’ve heard the e46 zhp gold tag from the late model 330ci trumps all, but I think it was mostly made for the American market, so a rhd maybe hard to come by. I need to do some more research on that 

LHD only and it's comparable to the "purple tag" rather than the Z3 rack IIRC.

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Does the purple rack have slightly more overall travel than the standard E36 rack?

I recently failed a warrant because a new anal guy at VTNZ noticed 2 tiny rub marks on my inner guards where the wheels just rub slightly from time to time (20mm mark in the underseal but no metal exposed). I'm sure it didn't do this prior to the purple rack. I had to pop the boots and put a 3mm spacer on each rack shaft end to reduce the travel - once done there was no issue with the warrant.

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I'm not 100% sure now, I measured it back in the day, I think the purple tag + e46 inners are 10mm too much for the e36, which is why I got my e36 inners machined to allow internal venting. I think the racks have the same travel.

That's a picky WoF! you can get OEM rack stops if required.

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On 1/8/2021 at 12:16 PM, M3AN said:

LHD only and it's comparable to the "purple tag" rather than the Z3 rack IIRC.

Thought it would be. 

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On 1/8/2021 at 7:26 PM, wrs said:

Does the purple rack have slightly more overall travel than the standard E36 rack?

I recently failed a warrant because a new anal guy at VTNZ noticed 2 tiny rub marks on my inner guards where the wheels just rub slightly from time to time (20mm mark in the underseal but no metal exposed). I'm sure it didn't do this prior to the purple rack. I had to pop the boots and put a 3mm spacer on each rack shaft end to reduce the travel - once done there was no issue with the warrant.

I have the same issue with right  tyre rubbing and the reason is the purple rack has a longer stroke than the stock one 

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