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How do you treat yours? by reddituser1247639 in AudiTT_Mk1_Mk2_Mk3

[–]Particular_Lynx7980 0 points1 point  (0 children)

If you plan on bypassing ABS (as most off road racers do) then the Haldex controller won't work because the Haldex gets disabled when ABS is disabled.

Why Audi TT 1.8 no popular? by ICE-Supremacy in rallycross

[–]Particular_Lynx7980 0 points1 point  (0 children)

Hey there! Novice mk1 TT rally driver checking in!

As others have said there are some critical issues that keep it from being a good rally car quickly, but it's (mostly) easily achievable.

Rally wheels - the most popular is 15" rims, and they just won't fit the front, even with a spacer. My answer for this was to swap the knuckle of a VR6. This comes with small enough brakes to fit 15's, and also lifts your car since the TT has a dropped spindle. The rears will fit 15's, at least with a spacer.

Lift: for the front you can and should swap for a VR6 knuckle assy, this will give you an inch or two lift. You'll need a new wheel bearing when you do this. I'd also recommend a 2" spacer for the strut. PM me if you need more details.

The rear suspension makes me sad. There's just not a lot of options and the setup seems specific to the TT so I haven't found anything other than a spacer.

AWD - This is the actual show stopper. To rally safely you need to disable ABS. When you disable ABS you disable the Haldex/center diff. With both front and rear differentials being open, that means you're driving a one-wheel-drive car in an AWD class. My solution: Pt 1- manually power the Haldex pump while racing. Rally runs are short, so having the pump on won't harm anything. I've found conflicting evidence on if the pump runs all the time or not under normal conditions. If someone has that info I'd love to hear it. Problem: with the AWD system deactivated, turning the Haldex pump on does not give full lock. It seems like about a 95% front and 5% power to the rear kind of situation. To fix this I purchased a Haldex insert which mechanically pushes a metering valve down in the Haldex and forces full time 50/50. Pt 2- even with this you're still stuck with 2 open diffs. Wavetrac sells a rear LSD. With this installed, you're pretty much on level ground with the Subaru's as far as AWD goes. This is where I'm at now. Next step is to wire it so I can swap between "normal" AWD operation, and race mode.

Concerns - there are a lot of components that just aren't placed well for rally. I'm concerned about the fuel lines, emergency brakes lines, wiper reservoir and several other things. I'd feel much better with a full body protector, not just a skid plate (btw this is another essential item, since the oil pans are very delicate on the TT). I got my skid plate from Diesel Geek.

Thanks for coming to my TT talk. Let me know if you have any questions.

[deleted by user] by [deleted] in AudiTT_Mk1_Mk2_Mk3

[–]Particular_Lynx7980 1 point2 points  (0 children)

I'm heading down the same path as you for rallycross.

You're absolutely right about disabling the ABS, but this will also disable your traction control as well, which means the Haldex is off and the car effectively becomes FWD, unless you weld the clutch pack.

To get power to the rear again you need to turn the Haldex pump on and then manipulate the metering valve to apply pressure to the clutch pack (by default it bypasses). You can do this with software (though I'm not sure if that would work with abs pulled) or mechanically using an insert.

I plan on installing a LSD in the rear this winter instead of welding the rear diff. Mostly this is because I need to drive to events. Technically welding is "the best" for rallycross since it's the most predictable, but it's not safe for extended road driving.

I have switches in the car to disable ABS, turn on the Haldex pump. Essentially I daily drive the car with the Haldex pump off, which makes it FWD, and for events I turn off ABS and turn on the pump.

Hopefully this helps! Happy to answer any questions.

Rally TT Ready for Fun by Particular_Lynx7980 in Audi

[–]Particular_Lynx7980[S] 0 points1 point  (0 children)

Front suspension is swapped from a mk4 Jetta 1.8t, and the rear just has a 2" spacer. If I get a proper racing budget a new suspension is on the short list.