Ok guys, i'm newly registered on this forum, but have been reading for about 2 yrs. anyway, i have a 2001 ttq 180hp i just finished my basic super k04 swap with custom FMIC, DP, diverter relocation, turbo inlet hose,10lbfidanzaflywheel, etc and now i'm having problems with my rear end.All i did to my rear was put in new bushings and change the rotors and pads. no other upgrades....yet. Now when i started driving the car, it feels like a bump every 1 second interval, and the harder i accelerate the louder and harder it gets. it does not increase in frequency, which led me to believe that i was my hadlex trying to engage. So i went to the rear and unplugged the harness mountedto the back of the differential. the bump went away, but now i'm only FWD. so whatsthe deal. it worked fine before i took the car appart. it satforonly 2 weeks. mytires in the back ar larger than the front, which affected traction control,but i didnt have the moneyfor all new tires, (which i'm getting in 2 weeks). Sois my haldex shot or are my brakes engaging? i'm assuming haldex, but why all of a sudden? and could it be not engaging because of the bigger tires in the back. they are only slightlywider, butbigger profile. Please help. this has got me truly stumped. ( i was thinking the haldex clutch whent out, but the bump says its still working)

heres a list on my car

180ttq
giac chip
k04-01
2.5 DP no cat (no CEL either, made an elbow for the #2 sensor)
forge inlet hose
forge diverter, relocated at throttlebody
injen CAI
FMIC with 2.5" tubing all hard pipe and as short as possible, (runnig over the top of the engine)
Fidanza flywheel
Spec stage 4 clutch
Zimmerman crossdrilled rotors with pagid pads front
new stock rear with pagid pads
powerflex bushings front/rear
modshack defcon kit front

soont to come
modshack boostmachine
modshack 225 **** maf
380 or 440 cc injectors

The car is super strong rigth now,

 

you cant mix tires on these quatrro cars its a big no no have you changed the haldex fluid and filter every 20k? get a vag com from ross-tech and it has a troubleshooter for the haldex coupling....i hate to say it but it sounds like your rear diff or haldex might be shot.

 

Did you ever VAG-COM it to see if there were any codes? It could be a couple of things... a failing Haldex controller module is one possibility short of a complete failure of the Haldex drive itself. Have you changed the Haldex fluid and filter every 20K miles?

When you say " the tires in back are larger than the front" how much larger? Are we talking same rolling circumference or are they signficantly larger diameter? The Haldex itself can handle about a 5% difference in tire circumference without any prob, but if you have much larger difference front and rear that could be your problem.

 

the dealer did most of my maintainance until now, so its at about 20k since the last time it was in for its final warranty work. i guess i have to change the tires asap, but why now, why not before i took the car appart? the tires are definitely a problem so i'll get that taken care of right away. i sure hope that thing is not done for. anyone know how much the clutch pack costs forthe haldex unit?

 

also i do have vagcom and as of this moment i have no codes at all. i checked it numerous times.

 

http://www.carbibles.com/tyre_bible.html

A little more than halfway down, theres a tire size calculator. If your fronts and rears are different profiles, enter one in the 'current' side, and the other in the 'new' side. Calculate both of those, and then calculate the difference.

 

Speculating here, but it sounds like your tires sizes are different enough to exceed the 5% threshold to where the abs / haldex could be sensing slippage and kicking-in one or the other. I wonder if unplugging the Haldex harness disconnets rear abs as well? Were your tires different sizes before you did the recent work?

 

could it be you have rotational tyres on and they are wrongly set up??

 

so im acctually at 10% difference, and based on that, the haldex thinks i'm burning out in the front as my rears spin slower. I think thats why it feels like its trying to engage. I disconnected it for now until i get my new tires and wheels. I want to go back to 18", so i can have more tire profile. what puzzles me is the fact that i had the tires on before, and i think i just turned traction control off and it would stop. but now it doesnt. I'll have to do the fluid change now as well and if i have to change the clutch, then so be it. a couple extra hundered wont kill me now. I've already put plenty of money into it. 1200 to fix the tranny alone, but it drives great now. (syncros went out on 2nd gear)

 

just get the tyre rotation right