Upgrading Front Hub Carriers to Improve Handling

[DriverTom]

Hi All!

This is my first time posting on Briskoda, I have been a long time lurker and have decided to contribute back to the community having used a number of the "How To" guides hosted here. 

 

The first thing many of us do to improve the handing is lowering the car using springs, but this has a drawback in that the lower control arm now sits at an angle that reduces camber as the strut compresses during corning. This is a "feature" designed into all the PQ24 platform vehicles (Fabia, Polo, A1 & Ibiza) so that when pushing on the car will under steer safely until the loads are reduced. Even the "performance" variants share the same geometry at the front and rear so there are no benefits to be had from raiding those parts bin. Take a look at how close the ball joint nut is to the bottom of the wheel bearing on a VRS Fabia.

 

 

 

A friend of mine was building a Leon track car and he mentioned that there is a popular mod in the MK4 Golf community to fit the "Wide Track" hubs and wish bones from a Mk1 Audi TT. This pushes the lower ball joint down and out, improving turn in by increasing static camber and increasing camber gain in a turn.

 

I bought a set of TT hubs to play with and discovered that the strut diameter and drive shaft splines were the same as the Fabia, however the ball joint taper is much deeper. Undeterred I had some spacers machined up so the standard Fabia ball joint would fit the TT hub assembly and fitted the whole shooting match to my car! Had the tracking adjusted first as the toe out was insane and then took it for a spin. With the TT hubs installed the static camber was around -3 degrees and castor at +5. The front was a bit more nervous in a straight line but the turn in and cornering was AMAZING!! It was so much harder to get the front to wash away into a round about, to the point where I could get the rear inner wheel to lift, with no rear anti roll bar!

 

Here you can see the extra distance between the ball joint and the hub on the TT carriers.

 

There was a downside though, no abs sensor meant no speedo...... or ABS........ or traction.......or air conditioning (fans are turned on and off by road speed apparently). I found a company that manufactures magnetic strips for wheel bearings and had them make a set of ABS rings that would fit my TT hubs, these were fairly expensive as they were one offs but proved to be unreliable as the clearance between the ABS sensor pick up and the ring needs to be held very accurately to function.

 

I mothballed the TT hubs for a couple of years trying to engineer a solution to getting a reliable ABS signal from the wheel and figure out a way to reduce the extra static camber. 

Fast forward to a few weeks ago and I get a go in an Audi S1 Quattro. Surprise, surprise, my interest in the  wide track project is rekindled. A look through the Audi parts bin and they've only gone and solved my original problem.

 

 

The S1 Quattro hubs have a larger distance between the ball joint and wheel bearing than the Fabia VRS but less than the TT carrier. It  takes a standard PQ24 strut, wheel bearing and ABS sensor, there is also a 312mm disc sized splash guard as standard ready for a brake upgrade. This hub carrier should give us more static camber and more camber gain in the corners whilst working with all the standard equipment on the car. 

 

I am having these hubs fitted on Friday and will keep you guys updated how I get on, including a before and after of the geometry.

 

Cheers

 

DriverTom

 

[DriverTom]

One more thing I forgot to mention is that I'm fitting a set of Audi TTRS lower ball joints at the same time to try and increase the castor. Should make for some fun on the drive home to see how much more grip the front end has!

[DriverTom]

So here are figures for a standard Fabia fitted with just TTRS lower ball joints. The camber is now at about -1.5 (with me sat in it). Unfortunately the alignment machine didn't print out the castor reading for us to see. 

[Mickmartin]

Amazing write up I'm surprised there been no more interest, How long you had the set up on now and is there any signs of tyre wear? Myself like other used mk2 Mondeo droplinks when lowering the car help in a similar situation.

 

And also is it cost worthy?

 

Keep continuing to write up on this mate, I'll be interested to see your final results.

[rum4mo]

Yes it is people trying crazy/stupid things and getting a good result that keeps us going!

 

I am on a Polo forum and I have just discovered that on certain earlier Polos (pre Fabia ones), that the lower swivels are the same on normal cars and GTIs, except the RHS one for normal cars gets fitted to the LHS on GTIs and vice-versa, someone bought a set/pair of lower wishbone assemblies via eBay for his GTI and one side has ended up with reduced camber, which sounds like they are two of the same item and not a pair fitted the wrong way round on the car. 

[Kgod1991]

Keep posting results and cost

[DriverTom]

The factory fitted lower ball joints on my car were backwards also! They are fitted that way to reduce castor and make the front under steer sooner.  The TTRS ball joints that are on my car now are positioned as far forward as I could mount them. It involved slotting the inboard hole in the wishbone but I now have way more adjustability.

[DriverTom]

1 minute ago, Kgod1991 said:

Keep posting results and cost

So far two Audi TTRS ball joints were £40 and the pair of Audi S1 Quattro hubs were £100. I didn't get the afternoon off today so it will be a week or so now before these hubs are installed 

[JGrindel]

This is a good thread!! Interested to hear how this turns out

[DriverTom]

So I've been running this setup for a couple of months now to prove the concept and after having to change a bent lower track control arm decided to document the installation should anyone else want to try it.

 

First we start with a new arm to modify. I transferred across the poly bushes I had fitted, noting the rear is oriented for maximum castor (you will see this becoming a theme later on)

 

 

 

[DriverTom]

Next we need the Audi TTRS ball joint to size where to drill the new mounting holes. I dropped the bolts through the 2 holes that line up and pivoted the ball joint forwards so that both slots were bottomed out (maximum castor position). I knew from a few months ago that this position would give about -1.5 degrees of camber on a standard car and I don't believe it needs any more than that for a fast road setup. It is possible to achieve more camber by pushing the ball joint fully outboard but this is at the expense of castor. Now we can see the third bolt is going to need some room before we can drop it in, this is where the step drill comes into play!

 

 

 

[Ootohere]

This project might interest some that may not have seen the thread.

http://briskoda.net/forums/topic/374661-mk2-fabia-rs-trackday-and-auto-x-project

 

[DriverTom]

Just now, Offski said:

This project might interest some that may not have seen the thread.

http://briskoda.net/forums/topic/374661-mk2-fabia-rs-trackday-and-auto-x-project

 

I totally stood on the shoulders of FDV when putting together this guide, as I understand he was the first to publicise this mod on Briskoda. 

[DriverTom]

Here you can see the new 10mm hole drilled to accommodate the third bolt. Because of the increased size of the ball joint mounting area you will have to bolt it up from the bottom of the track control arm. And for those of you worried about the strength of this arrangement, I had the unfortunate luck to clobber a monster pot hole earlier this week that bent the arm without shifting the ball joint mount or bolts at all.

 

[DriverTom]

Here is the ball joint fitted with a set of M10 grade 12.9 cap head bolts using the TTRS nuts that came with it.

[DriverTom]

If you are doing the ball joints along with the Audi S1 (quattro) hub carriers the you will need to use the standard Fabia nut to mount the tapered portion to the lower mounting point as the machining there is not wide enough to take the TTRS nut.

 

Fabia nut on the left, TTRS nut on the right:

 

[DriverTom]

And so the question is what are the benefits of the Audi S1 quattro hubs (on the left) over the standard Fabia hubs (right)?

 

 

 

[DriverTom]

The increase in distance between the hub and the ball joint mount means that when the car is back together the lower track control arm looks like this.

 

 

 

The arms pivot points are now sat much lower meaning that as the strut compresses during cornering we get much more dynamic camber. This should keep the contact patch of the tyre flat against the tarmac for longer, increasing grip and delaying understeer. The added castor settings will also be adding camber as the wheel is turned further into a corner. Subjectively I feel the initial turn in has improved but this could be because the toe in is now set to 0 degrees.

 

 

[rum4mo]

Maybe I've missed a bit, but it looks like you have fitted TT wishbone rear bushes, ie solid ones to these wishbones?

 

Also like the idea of using proper well strong enough cap headed bolts!

[DriverTom]

10 minutes ago, rum4mo said:

Maybe I've missed a bit, but it looks like you have fitted TT wishbone rear bushes, ie solid ones to these wishbones?

 

Also like the idea of using proper well strong enough cap headed bolts!

It's Fabia Superpro kit SPF3397K which does also fit the TT, MK4 Golf etc.

[rum4mo]

There does to be a revival maybe on people wanting to upgrade these rear bushes due to them ripping to easily in cars like Polo etc, which seems strange as the standard voided part has been in use for years in Golfs/Leons/TT for years so if they were too flimsy I'd have expected VW Group to wise up and sort them out - but these cars are a lot heavier than Fabia/Polo/Ibiza so I wonder why they are failing in these smaller/lighter cars. My wife's August 2015 ended up with a ripped one by the time it was 3 years 18.5K miles old.

[DriverTom]

I'm hoping to get the final laser alignment done on Wednesday and will post the results then. Does anyone have a 4 wheel printout from a standard car to compare it to?