RS4 Steering Rack Upgrade DIY

[Denio24]

So this is actually a thing not many people may know about. Speculation was on the net that the RS4 supposedly had a tighter steering ratio, and I found out myself that it actually does. I hopped on the parts catalog online and found the rs4 part number and i found myself a unit from a local junker for about $50. I see units on ebay going for $150. 8E1422054C. I did compare the racks side by side and they are quite different internally. I made a quick video providing explanation. The stock A4 rack has a straight cut tooth rack, the RS4 has an angled gear design and im sure the pinion is different as well. If you compare the lock to lock turns inside of the car one may think that the ratios are the same but with the rack removed from the vehicle it is much easier to compare as there is no added factor of steering wheel slop, loose joints, etc. The ratio comes out to just under 14.9 which confirms the info on the net that the ratio is around 14.5. While I did find that there was an even tighter steering ratio around 13.1 perhaps that was from a b5 because the part number I have was from an RS4. Pictures and more to come.

Before removing the steering column bolt and the rack itself you want to disconnect the power steering return line that goes after the rack and empty the lines by moving the steering wheel lock to lock. This will help considerably. You can also empty the system by running the car with the line disconnected for a max of two seconds.

First things first, you want to center your steering wheel to straighten your wheels to make everything easier. Next step is to remove the 8mm hex bolt at the steering column.

Jack the car up from the front slightly and remove the driver side wheel, and slightly lift the passenger side wheel. Disconnect the tie rods from the knuckle on each side. You dont have to remove the passenger side wheel as long as you have access to the bolts. Loosen the steering rack bolts and remove the two bolts closest on the driver side. Keep the bolt on the passenger side 1 turn loose so you can swing the other side of the rack towards the car. Using some long extensions slide the extensions and 19 and 22 mm sockets up near where the driver side axle is and hit those bolts. This is much easier than tackling these bolts with box end or combination wrenches. Have a piece of paper towel prepared for a tiny bit of fluid to come out from the banjo bolts.

In preparation to remove the rack, undo the top strut mount bolts and swing the strut top hat outwards and to the front to give you clearance to remove the rack. Jack the knuckle from the lower control arm so it doesnt go anywhere. Remove the plastic dust cover, remove the steering column bolts and the last rack mounting bolt. Now you can easily remove your steering rack.

Great now you have your new rack, clean it up, clean the shaft with some scotchbrite to remove rust and wipe off with break cleaner.



Grease the rack end lightly with a moly grease..i just installed a fresh tube of molykote g4700



Time to button it up with new orings and the old boots since they weren't ripped.

You wil have to make a centering bolt that is M10x1.5 that looks like this



And it fits in here. This is only for installation and MUST be removed and replaced with the original bolt before you drive otherwise your wheels will not turn and you may damage your rack...doh.



Center the rack and you will find the hole



Install the rack again only mounting it on the bolt closest to the passenger side so you can swing it. Using new crush washers



Install the banjo lines. Using the set of extensions and reaching from bottom of the car up and through where the axle is, torque the bolts to spec (will be updated with specs).

Place the strut assembly back in place, install and torque the remaining steering rack bolts with blue loctite, and install the tie rods to the steering knuckle and torque to spec. Dont forget to remove the centering bolt after youve attached the steering wheel pinion with the 8mm allen bolt (torque to 22 Nm). Dont forget to add fluid, connect the lines, and bleed the rack.

https://youtu.be/KAYuyCN_4sc





Sent from my SM-G920P using Tapatalk

[Mech_Mike412]

Subscribed, it would be great to get a cheap rack that turns quicker than my stock A4's. It's weak, and just makes it feel like a "old person" car

Sent from my SM-G900V using Tapatalk

[Okedokey]

http://www.audizine.com/forum/showth...steering-ratio

[Denio24]

http://www.audizine.com/forum/showth...steering-ratio

That is a well known thread.

Sent from my SM-G920P using Tapatalk

[Rulty]

I was actually wondering about this as I hate to make a corner turning this damn wheel the whole way around is annoying. I always liked cars that drove like go karts :)

Sent from my Pixel using Audizine mobile app

[Denio24]

I was actually wondering about this as I hate to make a corner turning this damn wheel the whole way around is annoying. I always liked cars that drove like go karts :)

Sent from my Pixel using Audizine mobile app

A flat bottom steering wheel will also help

Sent from my SM-G920P using Tapatalk

[Rulty]

How so? Smaller diameter?

Sent from my Pixel using Audizine mobile app

[Denio24]

How so? Smaller diameter?

Sent from my Pixel using Audizine mobile app

Easier to turn around. Smaller circumference so its easier to get your hands around it lol.

Sent from my SM-G920P using Tapatalk

[Rulty]

Well smaller diameter would change the effective ratio in a way I don't have a problem with getting my grimy hands around it lol just annoying to have so many turns with the wheel

Sent from my Pixel using Audizine mobile app

[Denio24]

Well smaller diameter would change the effective ratio in a way I don't have a problem with getting my grimy hands around it lol just annoying to have so many turns with the wheel

Sent from my Pixel using Audizine mobile app

It wouldnt change the ratio but it would definitely make it easier to turn. That may be my next upgrade. There is some polish company that makes custom fbsw's forgot what they were called.

Sent from my SM-G920P using Tapatalk

[Rulty]

Well your hand wouldn't have as far to travel from lock to lock, but with the smaller diameter it may make the force needed to turn the wheel more,doubtly very much stiffer, but you in theory would be losing leverage on the wheel no?

Sent from my Pixel using Audizine mobile app

[Denio24]

Well your hand wouldn't have as far to travel from lock to lock, but with the smaller diameter it may make the force needed to turn the wheel more,doubtly very much stiffer, but you in theory would be losing leverage on the wheel no?

Sent from my Pixel using Audizine mobile app

On that note you are correct, more torque would have to be applied but that are where the electric power steering assist units come in. It has also been found that there are different relays for the a4 vs rs4.

Ratio would be unaffected as you would still need to turn the wheel in the same amount to turn the wheels lock to lock.



Sent from my SM-G920P using Tapatalk

[Rulty]

Hmm interesting I was think smaller circumference would mean less travel....or more travel.....I'm just confused now either I'm sure it's a nice upgrade!

Sent from my Pixel using Audizine mobile app

[Nollywood]

It wouldnt change the ratio but it would definitely make it easier to turn. That may be my next upgrade. There is some polish company that makes custom fbsw's forgot what they were called.

Sent from my SM-G920P using Tapatalk

I think you've got it the wrong way round.

A smaller diameter wheel will effectively gear the rack action higher, albeit artificially. Less turns lock to lock. However, it won't make it easier to turn the wheel, it'll require more effort.

[Denio24]

How is it less turns lock to lock if the size of the steering wheel has nothing to do with the gearing of the pinion. The rack will always have a fixed amount of rotations for the pinion. Pardon me if im wrong, because it has been a long day.

Sent from my SM-G920P using Tapatalk

[Rulty]

How is it less turns lock to lock if the size of the steering wheel has nothing to do with the gearing of the pinion. The rack will always have a fixed amount of rotations for the pinion.

Sent from my SM-G920P using Tapatalk

Yeah I misspoke there but the distance your hand travels is less so it's "faster" but I doubt my much

Sent from my Pixel using Audizine mobile app

[drewgold]

Trying to find the interchange numbers for the the B7 S4/RS4 steering racks. The main part number listed is 8E1422054C, but seems like 8E1422072F is an interchange number?

Part numbers for steering racks seem to be super confusing, there's the 'raised' part number on the rack which seems to be very broad, ie. 8E1422105B then the stamped more specific part number such as 8E1422072F

Anyone know how exactly these part numbers work?

[canadianA4B7]

s4 and RS4 racks are 100% the same by part number, the electronic devices on S4 and RS4 are the difference. Then add the 642 relay under the knee bolster. For complete rs4 feel.

[drewgold]

s4 and RS4 racks are 100% the same by part number, the electronic devices on S4 and RS4 are the difference. Then add the 642 relay under the knee bolster. For complete rs4 feel.

This what I thought, appears to be a few different revisions and part numbers though for the rack itself. Maybe depends on which year?

[tloft4]

How is it less turns lock to lock if the size of the steering wheel has nothing to do with the gearing of the pinion. The rack will always have a fixed amount of rotations for the pinion. Pardon me if im wrong, because it has been a long day.

Sent from my SM-G920P using Tapatalk

i know this is an old thread, but in terms of degrees, its the same, yet the larger the diameter, the further each degree is. if you had a 100ft steering wheel and a 1ft steering wheel and one full rotation (360deg) is lock, the bigger the wheel, the more you have to turn it. thats obviously very drastic but the comparison is the same.

[canadianA4B7]

This what I thought, appears to be a few different revisions and part numbers though for the rack itself. Maybe depends on which year?

I would ask the guy in the rs4 section c5vette65 or something (I never spell it correct thanks dyslexia) he sold me the rack and confirmed the part number differences at that time. Sorry I don’t have more info I took pics of it all when apart but cannot find them. I think my cloud got hungry and ate them.....

[rodgertherabit]

s4 and RS4 racks are 100% the same by part number, the electronic devices on S4 and RS4 are the difference. Then add the 642 relay under the knee bolster. For complete rs4 feel.

this is good info...

[rodgertherabit]

so the s4/rs4 racks are improved driving dynamics over the standard A4s?
=jsut want to confirm..

Also is this across the generations or b5 specific? b6/7 specific?

[Denio24]

I've checked the part numbers and like previously mentioned, the b7 s4 and rs4 racks are the same which are 14.5:1, as opposed to the stock a4 ratio of 16.3:1. I'm not sure where the 13.1:1 rack comes in but perhaps that was the b5 rs4 that had a 13.1:1, sources say ??, which I'm pretty sure it wouldn't be a direct fit as it was a different platform.

[Jayz691]

Reviving an old thread, cuz I need to replace my rack in my 07 a4q. Sprung a leak at the end, under the boot somewhere. Anyway, is the s4/rs4 swap direct? Just buy one and instal, or are there other things that need changed or modified? Like bokts in same place and everything, just different ratio rack? Tia

Sent from my VS995 using Audizine mobile app

[vce1232000]

a RS4 rack a few years ago. Direct in. You have to change the relay on the fuse panel to get full benefit. You wont be disappointed if you do

[Jayz691]

a RS4 rack a few years ago. Direct in. You have to change the relay on the fuse panel to get full benefit. You wont be disappointed if you do

K, thanx. I'll have to look for part #.

Sent from my VS995 using Audizine mobile app

[canadianA4B7]

642

[Jayz691]

642

What, last 3 numbers?? 8e1 422 642?

Sent from my VS995 using Audizine mobile app

[canadianA4B7]

What, last 3 numbers?? 8e1 422 642?

Sent from my VS995 using Audizine mobile app

One under the bolster is just labelled 642 from what I remember. That’s what I replaced on mine with rack added a cooler too (this stealth little bastard is re purposed from a Sierra truck trans cooler and fits perfectly where drivers IC was) steering is same as RS4. I ordered it by requesting “642 steering relay from 2007 Audi RS4”. I c VCE states “on fuse panel” but I don’t recal the Bentley specifying a steering relay in the panel itself (small door left edge of dash) If you pull off the lower knee bolster you look in through there and you should see a few relays I think oem in A4 is 641 iirc. They were off white in colour.

[vce1232000]

\ I c VCE states “on fuse panel” but I don’t recal the Bentley specifying a steering relay in the panel itself (small door left edge of dash) If you pull off the lower knee bolster you look in through there and you should see a few relays I think oem in A4 is 641 iirc. They were off white in colour.

You rite. my

[Nollywood]

My steering rack is servotronic as standard.

This rack was fitted to the SEAT Exeo 2.0 TSI and 2.0 TDI 170 models only. All other cars with engines below the 2 listed here are non-servotronic.

I must say it feels much better than my old B6 3.0 Avant Quattro Sport. I’m going to check what the actual rack part number is. There were quite a few improvements in the SEAT Exeo suspension and steering, compared to an A4 B6/7.

[Kevin C]

On my B6 I used wiring from a 2007 A4 B7 to retrofit a S4 RS4 Servotronic rack and relay. I used the S4 relay (actually a pwm control). One thing I notices was that the steering feel really depends on the tires. My winter tires felt pretty light at low speeds, the summer tires feel perfect even with just the S4 relay.

If it helps have pics of the part locations and list various part numbers of S4 racks:

https://www.audizine.com/forum/showt...th-Servotronic