GoatAutomotive
Autocross Champion
- Location
- Georgetown, TX
- Car(s)
- 2017 VW GTI SE, DSG
Last month, I started a big MQB LCA tech article to share, but things went sideways when I encountered issues with a fresh-out-the-bag set of RS3 control arm bushings, straight from the Audi dealer. Report below. It's a working draft, so I'll come back to it and clean it up, add pics where helpful, etc.
The RS3 Bushing Mod
(it's not what you think...)
In January of this year, I installed Whiteline's steel front LCAs to my car, and they were amazing. No more wheel hop. Front end felt Porsche-level precise. Absolutely awesome upgrade for under $180.
And that euphoric Fentanyl high lasted for about 2500 miles...
By May/June, the bushing had failed on the left front LCA (Driver side), and I didn't discover it in time.
Polyurethane is essentially a solid mold with little to no give/flex, which can make it marvelous (in the right durometers) for engine mounts, trans mounts, and suspension bushings that encase a standard collar and bolt, for pivoting like the hinge of a door. Poly reduces undesired "squish" in the mounts or suspension pivot points.
In the case of an MQB LCA with a "puck" that must allow the LCA to flex downward when the wheels droop, you're basically inducing suspension bind to the car when you trade rubber for poly on the rear bushing location
Yes, it will roll down the road fine under static vehicle load, but only in the beginning. Every time you put the car in the air and let the front tires droop, you're asking that poly bushing to flex and give where it was designed to stay solid and rigid. The stored energy of the coil springs pushing down against the bushing will always win the long battle.
I'm one of a half dozen who experienced premature poly bushing failure on a MQB LCA.
With the issue undetected (at the time), my failed poly bushing sent me flying off track in an easy corner of our 6/7/23 SCCA Track Night event. I couldn't understand why the front of the car felt so unsteady that day, even after a fresh alignment. It was several days after during the mechanical inspection that I found the damage:
(pics below)
Regarding material choices for improving the bushing performance of the OE MQB front lower control arms (LCAs):
1) Straight poly fails (Whiteline and other poly choices)
2) Poly wrapped around a ball and socket design works well if it stays lubricated (Superpro/Whiteline Aluminum LCA offerings)
...Is there a simpler solution for folks on a budget?
Yes. Solid rubber.
I did my homework and purchased a set of OE Audi RS3 LCA bushings for Stormy. There are currently two generations of RS3 for North America. The bushings I'll be discussing are for the 2017-2020 models. Part #81A-407-183
[See it here:] https://parts.audiusa.com/p/Audi__/...m-Bushing-Rear--Lower/68895617/81A407183.html
Saturday night, 9/23, my assistant and I finally attacked the install. Removal of the LCAs, and the failed bushings, was butter…until we made a horrific discovery:
The OE Audi RS3 bushings we received, from the dealer, are NOT compatible with the Mk7 GTI LCAs, nor the Whiteline Mk7 LCAs I was attempting to press them into.
The bushing bore on the stock Mk7 LCAs is ~64.22mm, ID. (OE Gumby bushings in the right for reference)
The Audi RS3 bushings I received were 65.11mm, OD.
That’s almost a 1mm delta on an interference-fit item. Think of a porn star with a huge…never mind. It’s not gonna fit. Anti-seize/lithium grease/soapy water be damned.
We wasted hours trying to figure out this issue:
-locating a HD hydraulic press and adapters (in case more cowbell was needed)
-bothering Tony (Derhase) over on the east coast (to measure his BFI bushings)
-researching install methods online (in case my method with the ball joint press was insufficient)
In all of that time, I hadn't measured the bore and bushings. Didn't think that was the issue. I should have used my micrometer sooner, but holding up the Whiteline poly bushing, the OE VW bushing, and the Audi RS3 bushing, they looked visually the same size. And I had no reason to suspect a size variance based on the research I’d completed.
GTI = MQB.
RS3 = MQB.
…Same DNA, why would the bushing dimensions be any different?
9/23 OUTCOME:
Late night, incomplete repair…I had to miss yet another car cruise with my club that Sunday morning (9/24), and as collateral damage, I let my young son down. He normally goes on the events with me, looks forward to them, and is super popular with all the members. They ask about him with weighted interest when he’s absent.
Tony sent me picture confirmation on 9/24 that the BFI RS3 bushings are indeed the correct size. ~64.22mm, so I ordered up a set, and returned the Audi RS3 bushings to the dealer for a refund - restocking fee.
I measured the BFIs as soon as they arrived, and they checked out.
New BFI bushings are going in in the next week, along with a custom subframe centering kit I'm working on that uses ARP hardware.
Punishment:
For 9/24, in order to get the car back on the ground and driving under its own power, I had to dust off my OE GTI LCAs, with their garbage truck VW Gumby bushings, and run them for the past month.
Words alone cannot depict how truly terrible those suckers are. With no other changes to the car's suspension, it's back to feeling like a shopping cart at WalMart.
-Apply torque/power: toe angle changes.
-Change lanes quickly and get on power: toe angle changes.
-Try to load the car up mildly into a corner: front end shifts a bit from the bushing slop.
It's rubbish! (as my Brits would say)
Hope this helps educate some folks.
@DerHase @tigeo @GTI Jake
The RS3 Bushing Mod
(it's not what you think...)
In January of this year, I installed Whiteline's steel front LCAs to my car, and they were amazing. No more wheel hop. Front end felt Porsche-level precise. Absolutely awesome upgrade for under $180.
And that euphoric Fentanyl high lasted for about 2500 miles...
By May/June, the bushing had failed on the left front LCA (Driver side), and I didn't discover it in time.
Polyurethane is essentially a solid mold with little to no give/flex, which can make it marvelous (in the right durometers) for engine mounts, trans mounts, and suspension bushings that encase a standard collar and bolt, for pivoting like the hinge of a door. Poly reduces undesired "squish" in the mounts or suspension pivot points.
In the case of an MQB LCA with a "puck" that must allow the LCA to flex downward when the wheels droop, you're basically inducing suspension bind to the car when you trade rubber for poly on the rear bushing location
Yes, it will roll down the road fine under static vehicle load, but only in the beginning. Every time you put the car in the air and let the front tires droop, you're asking that poly bushing to flex and give where it was designed to stay solid and rigid. The stored energy of the coil springs pushing down against the bushing will always win the long battle.
I'm one of a half dozen who experienced premature poly bushing failure on a MQB LCA.
With the issue undetected (at the time), my failed poly bushing sent me flying off track in an easy corner of our 6/7/23 SCCA Track Night event. I couldn't understand why the front of the car felt so unsteady that day, even after a fresh alignment. It was several days after during the mechanical inspection that I found the damage:
(pics below)
Regarding material choices for improving the bushing performance of the OE MQB front lower control arms (LCAs):
1) Straight poly fails (Whiteline and other poly choices)
2) Poly wrapped around a ball and socket design works well if it stays lubricated (Superpro/Whiteline Aluminum LCA offerings)
...Is there a simpler solution for folks on a budget?
Yes. Solid rubber.
I did my homework and purchased a set of OE Audi RS3 LCA bushings for Stormy. There are currently two generations of RS3 for North America. The bushings I'll be discussing are for the 2017-2020 models. Part #81A-407-183
[See it here:] https://parts.audiusa.com/p/Audi__/...m-Bushing-Rear--Lower/68895617/81A407183.html
Saturday night, 9/23, my assistant and I finally attacked the install. Removal of the LCAs, and the failed bushings, was butter…until we made a horrific discovery:
The OE Audi RS3 bushings we received, from the dealer, are NOT compatible with the Mk7 GTI LCAs, nor the Whiteline Mk7 LCAs I was attempting to press them into.
The bushing bore on the stock Mk7 LCAs is ~64.22mm, ID. (OE Gumby bushings in the right for reference)
The Audi RS3 bushings I received were 65.11mm, OD.
That’s almost a 1mm delta on an interference-fit item. Think of a porn star with a huge…never mind. It’s not gonna fit. Anti-seize/lithium grease/soapy water be damned.
We wasted hours trying to figure out this issue:
-locating a HD hydraulic press and adapters (in case more cowbell was needed)
-bothering Tony (Derhase) over on the east coast (to measure his BFI bushings)
-researching install methods online (in case my method with the ball joint press was insufficient)
In all of that time, I hadn't measured the bore and bushings. Didn't think that was the issue. I should have used my micrometer sooner, but holding up the Whiteline poly bushing, the OE VW bushing, and the Audi RS3 bushing, they looked visually the same size. And I had no reason to suspect a size variance based on the research I’d completed.
GTI = MQB.
RS3 = MQB.
…Same DNA, why would the bushing dimensions be any different?
9/23 OUTCOME:
Late night, incomplete repair…I had to miss yet another car cruise with my club that Sunday morning (9/24), and as collateral damage, I let my young son down. He normally goes on the events with me, looks forward to them, and is super popular with all the members. They ask about him with weighted interest when he’s absent.
Tony sent me picture confirmation on 9/24 that the BFI RS3 bushings are indeed the correct size. ~64.22mm, so I ordered up a set, and returned the Audi RS3 bushings to the dealer for a refund - restocking fee.
I measured the BFIs as soon as they arrived, and they checked out.
New BFI bushings are going in in the next week, along with a custom subframe centering kit I'm working on that uses ARP hardware.
Punishment:
For 9/24, in order to get the car back on the ground and driving under its own power, I had to dust off my OE GTI LCAs, with their garbage truck VW Gumby bushings, and run them for the past month.
Words alone cannot depict how truly terrible those suckers are. With no other changes to the car's suspension, it's back to feeling like a shopping cart at WalMart.
-Apply torque/power: toe angle changes.
-Change lanes quickly and get on power: toe angle changes.
-Try to load the car up mildly into a corner: front end shifts a bit from the bushing slop.
It's rubbish! (as my Brits would say)
Hope this helps educate some folks.
@DerHase @tigeo @GTI Jake
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