Emmanuele Design Audi A4 (B9) Bump Stop Kit

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Audi A4 (B9) Bump Stop Kit

For those who have lowered their B9 A4, we offer our shortened bump stop kit. Featuring a shorter, stiffer bump stop, this kit will allow your lowered vehicle to maintain proper travel to bump stop engagement. Most valuable for non-sport A4's, sport package vehicles (A4 and S4) would also find value in a slightly improved ride quality.

Sold in pairs.

Read more about bump stops and our measurements BELOW.

B9 A4 Bump Stop Discussion

As there has been a lot of talk regarding the bump stops and how they may affect lowering the A4, we thought it would be helpful to share a few of our thoughts and measurements.

Purpose: The bump stop functions as a helper spring, adding spring rate to the coils in order to prevent the shock from bottoming. It will also limit overall suspension travel. Each bump stop features a progressive spring rate, usually with a soft initial engagement that will get firmer as the bump stop compresses further.

Trim the bump stops? This is a frequently used term when lowering a vehicle, and is usually the subject of debate. When you lower a vehicle, the shock rod length becomes shorter, thus decreasing the distance until the bump stops engage. To keep this distance the same as stock, many users will opt to trim the bump stops.

B9 A4 Rear Standard (8W0512131F) Bump Stop Length: 4.90” / 125mm
B9 A4 Front Standard (8K0412131E) Bump Stop Length: 3.189” / 81mm
B9 A4 Front Sport (8K0412131F) Bump Stop Length: 2.834” / 72mm
B9 A4 eMMOTION Front Bump Stop: 2.150” / 55mm

How do we know how much to trim?

By taking the motion ratio (a factor of how much the wheel travels in relation to the coil/strut), we can get a pretty good idea of how much should be trimmed for proper functionality.

Front Motion Ratio: 0.75
Rear Motion Ratio: 0.80

This means that for every inch the wheel travels, the shock/strut will travel by approximately the above values. So in an ideal world, the front bump stops would be 0.75” shorter for every inch the car is lowered. In most cases, this isn’t possible due to shock travel and/or wheel interference, so a compromise is made.

Lowered Measurements:

On a B9 A4 (standard suspension) test vehicle, which was lowered 1.6” front and rear, we measured the shock rod lengths at:

Front: 3.025”
Rear: 4.233”

This means that on the standard suspension (lowered 1.6") without any bump stop modification, you will be sitting on the bump stops with the car at ride height. In terms of feel, this will lead to a firmer feel with a more notable bounce as the dampers try to handle the increased energy. We have found the best results on the non-sport suspension by trimming 1.2" in the rear, combined with our front bump stops. This allows enough travel for the shock rod, while still limiting rubbing with aggressive wheel setups (some offsets could rub with this amount of travel). This number will change based on how much the car is lowered on stock shocks/struts, but the motion ratios can serve as a good reference point for calculating how much to trim. We always recommend starting with less, and trimming more if needed. We prefer to trim from the top of the bump stop, as this is the firmest rate portion. Hope this helps answer some questions!

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Returns Policy
You may return most new, unopened items within 30 days of delivery for a full refund. We'll also pay the return shipping costs if the return is a result of our error (you received an incorrect or defective item, etc.).

You should expect to receive your refund within four weeks of giving your package to the return shipper, however, in many cases you will receive a refund more quickly. This time period includes the transit time for us to receive your return from the shipper (5 to 10 business days), the time it takes us to process your return once we receive it (3 to 5 business days), and the time it takes your bank to process our refund request (5 to 10 business days).

If you need to return an item, simply login to your account, view the order using the "Complete Orders" link under the My Account menu and click the Return Item(s) button. We'll notify you via e-mail of your refund once we've received and processed the returned item.

Shipping
We can ship to virtually any address in the world. Note that there are restrictions on some products, and some products cannot be shipped to international destinations.

When you place an order, we will estimate shipping and delivery dates for you based on the availability of your items and the shipping options you choose. Depending on the shipping provider you choose, shipping date estimates may appear on the shipping quotes page.

Please also note that the shipping rates for many items we sell are weight-based. The weight of any such item can be found on its detail page. To reflect the policies of the shipping companies we use, all weights will be rounded up to the next full pound.

Ecotune do not assume responsibility for the use of this part on public roads in the UK or abroad where emissions controls have been removed. It is the customer’s responsibility to ensure compliance with the rules and laws of the area of use. We would like to advise that it is illegal to remove any emission control devices or increase the exhaust noise limit on vehicles permitted to drive on public roads in the UK and most other countries around the world. Please check the rules and laws relating to this in your country. Any parts supplied or work carried out by Ecotune are strictly for off-road use and may fail an MOT test. This means that we cannot accept any responsibility for vehicles being driven on public roads where removal of emission control devices is prohibited. If you carry out this work at our premises, we would not be able to road test afterwards..