B7 servotronic to b6 1.8

[Peter07]

Hello.I want to install a servotronic steering system in my a4 b6 1.8t
Which b7 do you recommend buying 2.0 3.2 4.2.
Thanks for help.

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[shurur9]

Are they actually different part numbers?

[Kevin C]

Per the Audi corporate directive there is a different part number rack for every possible variation in the platform. Sunroof? different rack. Heated seats? different rack!!!! Seriously, the S4 got it own number, there is an ongoing debate if it actually ahs a faster steering ratio or not. PArt numbers vary depending on engine, year and if its a convertible. I have never seen an issue with swapping complete racks. On the S4 rack the tooth pitch does look different than the A4. I used an S4 rack, any B7 will have the servotronic setup. Feel is controlled by the servo relay, that seems to be 95% of the upgrade.

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

[rollerton]

Per the Audi corporate directive there is a different part number rack for every possible variation in the platform. Sunroof? different rack. Heated seats? different rack!!!! Seriously, the S4 got it own number, there is an ongoing debate if it actually ahs a faster steering ratio or not. PArt numbers vary depending on engine, year and if its a convertible. I have never seen an issue with swapping complete racks.

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

One reason for so many different racks is different suppliers/ manufacturers- or they can potentially need a different part# just due to country destination. Another one is a few different power steering pulley sizes. From what I can tell they're nearly ALL interchangeable physically, including A3, A6, S4, Passat, etc etc.. I found that the C5 V8, Audi 100, 400, and VW Vanagon (among a hundred other cars) all use the same power steering pump. They ARE interchangeable- but unless you know what it's doing at what rpm it's all just guess work and experimenting.
It's like fuel pump assemblies in these cars. The B6 3.0 may have an external return fitting that you can just plug then you can use it in a B7 2.0 - but they're not officially compatible- you just have to figure out which one works by buying a hundred and trying!

[Peter07]

Thanks for the tips, I think# Kevin C#has cleared up my doubts and I will be looking for a rack and pinion from an audi s4 b7.

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[krazeedrivr]

Anyone know of a good but cheap rack rebuilder? I used Rack Doctor in the past, but they went downhill and then out of business. I need to get a servotronic rebuilt.

[Gunnarrrrr]

Anyone know of a good but cheap rack rebuilder? I used Rack Doctor in the past, but they went downhill and then out of business. I need to get a servotronic rebuilt.

the only good and cheap rack rebuilder these days is yourself unfortunately. Try ATG steering, I think the kit is HK0162 but I could be wrong, kevin has the same 8E1422072C as me and I think he rebuilt his too.

Also to the OP make sure you grab the appropriate servotronic relay (its not really a relay its a whole control module)
I tried running a 640 briefly with my B7 S4 rack and it tapered off the assist much later, making it feel way too light and twitchy above 40mph. the 638 and 641's cut the assist a lot earlier, and even earlier on a 642. Having an extremely tight ratio like the s4/rs4 racks with too much assist can make it very easy to accidentally crank the wheel at high speeds.

This is the list I compiled and I'm like 90% sure its correct.
628 - 8E0907307 - B6 A4
638 - 8E0907307A - B6 S4
640 - 8E0907307D - B7 A4
640 - 8E0907307F - B7 A4
641 - 8E0907307G - B7 S4
641 - 8E0907307E - B7 S4
642 - 8E0907307C - RS4
642 - 8E0907307H - RS4