Switch off rear wheals using cruise control

AlexTr

Registered User
Hi everyone!
Could someone help me.. I have info, that using cruise contol and it is connectod to fuse 41 some how, when you reach some speed(e.g. 50mph) - then 44 fuse could be disconnected.. Could someone share info?
 
Last edited:

leonwilliams

Registered User
Hi everyone!
Could someone help me.. I have info, that using cruise contol and it is connectod to fuse 41 some how, when you reach some speed(e.g. 50mph) - then 44 fuse could be disconnected.. Could someone share info?
Why would you want to do that I dont understand??

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AlexTr

Registered User
this method was used for better run on 1/4 mile race, that's my aim, thanks
P.s. I did a mistake, 44 fuse is for all wheel drive, not 41
 

DJAlix

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Disconnecting this would envoke the vehicles safety systems and the ECM would throttle back power so as to avoid an accident. If you want a two wheel drive car then you need to make a proper conversion etc. You could always put the car in to “dyno mode” which would be better.
 

AlexTr

Registered User
The main idea is to switch rear wheel in drag race, when you go straight, and after 40mph switch it... Ok, Does anyone know what is the speed in stock when Haldex is switching off? Because it doesnt work from some speed, I don't know this speed.
 

DJAlix

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The main idea is to switch rear wheel in drag race, when you go straight, and after 40mph switch it... Ok, Does anyone know what is the speed in stock when Haldex is switching off? Because it doesnt work from some speed, I don't know this speed.
Won’t work. The safety systems will kick in because the control modules will see the “disconnection” as a fault.
 

Damo S

Registered User
this method was used for better run on 1/4 mile race, that's my aim, thanks
P.s. I did a mistake, 44 fuse is for all wheel drive, not 41

If you want better 1/4 mile times then go to stage 1 or 2. Mine is stage 2 and at a guess I'd say it would just light the wheels up even in 4th if it wasnt using all of them.
 

pburv

Registered User
Stripping the car down to bare bones will give a similar result on 1/4 mile drag..At least it won't be messing with the car ecu??
 

Shawn8V

Registered User
This can be done through the use of a Haldex controller which plugs in to the haldex unit under the rear seats and you can control Parameter you have described.

Not cheap tbh, looking about £1k+ for the unit and you’d have to get them imported form either the states or Europe.

either get a map or strip the car for a quicker 1/4mile time tbh.
 

Dannymoto

Registered User
Disconnecting this would envoke the vehicles safety systems and the ECM would throttle back power so as to avoid an accident. If you want a two wheel drive car then you need to make a proper conversion etc. You could always put the car in to “dyno mode” which would be better.
I'm sure it kicks it out of dyno mode once it detects the rear wheels are moving?
 

DJAlix

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B5NUT

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You need to read that stuff, the A3 being haldex has a clutch to enable power to the rear wheels, so it can be front wheel drive only. The A3 does not use the torsen system like the larger Audi, which is permanent and uses "gears" as you put it.
 

Peter Peter

Registered User
You need to read that stuff, the A3 being haldex has a clutch to enable power to the rear wheels, so it can be front wheel drive only. The A3 does not use the torsen system like the larger Audi, which is permanent and uses "gears" as you put it.
So gears can be separated to stop rotating from transmission? Because when I went for transmission fluid replace, during pumping new fluid in, we start the car and run it on gear one .. all wheels been spinning..
 

B5NUT

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Yes that is what the haldex system does. Have a looking on the forum, where the haldex units have failed and they are spinning up the front wheels.
 

AlS3BE

Registered User
So gears can be separated to stop rotating from transmission? Because when I went for transmission fluid replace, during pumping new fluid in, we start the car and run it on gear one .. all wheels been spinning..

All wheels spin cause the fluids in the Haldex system can create enough force to rotate the wheels when they are off the ground but not enough to do anything else. It’s the same with a fwd car in the air. The wheels can spin when engine is started even though it’s in neutral.
the prop shaft will always spin regardless if the rear wheels are driven. at the rear end of the prop shaft there’s a electromechanical clutch controlled by the Haldex pump and when the ecu decides it needs rear drive it will connect the prop shaft otherwise the prop shaft is just free spinning. It’s good for fuel efficiency as the rears are only driven when needed as most of the time folk don’t need awd.
 

Peter Peter

Registered User
Yes that is what the haldex system does. Have a looking on the forum, where the haldex units have failed and they are spinning up the front wheels.
But but if am reading correctly on this site : https://jalopnik.com/audis-high-tech-new-quattro-is-about-to-****-off-its-bi-1760502139 ''decoupler ''
Is what separates or disconnects gear from the rear wheels and that been introduced in 2016 and named quattro as ultra.. But I believe A3 2013 to 2015 has permanent quattro ?
 

B5NUT

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That page is talking about longitudinal engine cars (A4, A6, A7, A8, Q7 etc), which in the past have always been torsen based quattro. Cars like the A1, A3 & TT have always been haldex so it's not permanent quattro, it's managed by the ECU/hydraulics/clutch system of the haldex unit.
 

Peter Peter

Registered User

AlS3BE

Registered User
Easy way to identify is if the engine points left to right(transverse) then it’s more likely Haldex system, ie part time awd. Haldex system is for small light cars as no one driving a small hatch wants a really long bonnet as it’s for compact cars.
Torsion/ultra cars have engines pointing front to back(longitudinal), full time awd and tend to be bigger cars. Think I got that the right way round.
 

Peter Peter

Registered User
Easy way to identify is if the engine points left to right(transverse) then it’s more likely Haldex system, ie part time awd. Haldex system is for small light cars as no one driving a small hatch wants a really long bonnet as it’s for compact cars.
Torsion/ultra cars have engines pointing front to back(longitudinal), full time awd and tend to be bigger cars. Think I got that the right way round.
I've seen A3 tdi ultra ... was wondering what's the diff. btw mine..
 

AlS3BE

Registered User
I've seen A3 tdi ultra ... was wondering what's the diff. btw mine..

the ultra name is used in the economical cars like a a3 tdi and normally fwd not Quattro/awd.
The Quattro ultra is a fuel efficient Quattro system similar to the Haldex system but used in longitudinal engine layouts as far as I know.
 

robsy

Registered User
Easy way to identify is if the engine points left to right(transverse) then it’s more likely Haldex system, ie part time awd. Haldex system is for small light cars as no one driving a small hatch wants a really long bonnet as it’s for compact cars.
Torsion/ultra cars have engines pointing front to back(longitudinal), full time awd and tend to be bigger cars. Think I got that the right way round.
Tell that to my transverse Celica gt4 with permanent torsen 4wd.
 
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