Best AWD/4WD conversion for MK1 Seat Leon [track] car?

[Rgm racer]

Cost aside, what would be the best possible [and maybe most straight forward] AWD/4WD set up that could be fitted to a Seat Leon [track] car?

Am aware some have fitted parts from S3 but understand haldex may not be best system and it tends to under steer similar to a FWD only due to it's more FWD than RWD bias?

Would a permanent and equal front/rear drive system be the best and possible to achieve?

Also is there an any actual difference between what people call a AWD or 4WD system?

 

[d1n93r]

dont know about the rest but the differance between awd and 4wd is, awd is constantly sending drive to all of the whels all of the time. 4wd the back wheels only get drive when the front one are spinning to fast. then the back ones kick in. hope this helps

 

[Darrens7887]

For the 4wd conversion, theres a few variations on how it can be done, but my research into the subject led my to belive that using the rear floor/subframe ect from an s3/A3 quattro is ultimately one of the best ways. an you can get a haldex controller to set the 4wd drive to how u want, an its always been reported to transform the feel of the s3 with the haldex controller fitted.

 

[grahams81]

Cost aside, what would be the best possible [and maybe most straight forward] AWD/4WD set up that could be fitted to a Seat Leon [track] car?

Am aware some have fitted parts from S3 but understand haldex may not be best system and it tends to under steer similar to a FWD only due to it's more FWD than RWD bias?

Would a permanent and equal front/rear drive system be the best and possible to achieve?

Also is there an any actual difference between what people call a AWD or 4WD system?

Hi Rob, i did loads of research before converting mine and the best you'll get is a 50/50 torque split..... this is by fitting any of the vw 4wd / awd traverse systems.

Impreza's / EVO's use adjustable centre diffs and are designed in such a way that the supplied torque is delivered to the centre diff then shared out to which ever axle so they can vary the power to the rear wheels (this allows them to run higher levels to the rear (i think my mates STi can run 70/30 bias to the rear - we don't have a centre diff design for our transversally mounted engines.... ours simply take drive from the front diff crown wheel and put it through a simple bevel box to change it through 90 degrees.

Audi quattro's (longitudinally mounted ones - not s3 or TT) use a similar design to the impreza's etc where you could make them bias to rwd..... they use Torsen diffs.
To get this done right you need to really mount the gearbox behind the front wheels... i think thats why the system isn't used on our transverse applications.

Due to the front engined design of the car and even with a 50/50 split, the car will inherently try and understeer a bit - but in a different way and at much higher speed than a fwd version of the same car.

Basically if you want 4wd your stuck with the haldex system or a massive project to fit an engine longitudinally and the power train. Or look into retrofitting Evo running gear.

Your probably already aware of how the Haldex system works, but in case you don't ----

So as we already know the propshaft is being driven by the transfer box which is turn being drive by the gearbox.....
In a OEM haldex equipped car the Haldex ecu uses information supplied to it via the can-bus system..... sensors include - abs sensors, throttle position, steering angle, acceleration etc etc...
Now the haldex ecu will decide when to lock the diff based on it's current information it's getting.
If the ecu wants to lock the diff it moves a small stepper motor which in turn moves a hydraulic proportioning valve.

The haldex system is quite simply put - a electro-hydraulic clutch.....

On the first generation Haldex systems they rely on wheel slip to lock - this isn't just a electronic requirement of the abs sensors but also a mechanical requirement.... the haldex clutch is made up of clutch plates that need to be forced together to enable drive to the rear wheels. The way they are forced together is by oil pressure - this oil pressure is first produced by the slipping action between the input and output shafts of the clutch assembly.

Over view of the clutch assembly -

Here is a simplified view of how the oil pump works -

Pics & further reading from - http://www.awdwiki.com/en/haldex/

Modifying the Haldex system -

There are performance haldex controllers (blue controllers etc) that can change the behaviour of the clutch system - these still use all the oem signals etc but the can lock sooner or stay lock under braking etc for added stability / engine breaking.
The only problem with these are the car has to have had a functioning haldex system already..... this could be an issue if you do the conversion.

There are also standalone haldex controllers that don't utilise the OEM sensors etc and are designed for people running conversions. You can normally turn the system on / off and use different settings for race / street / drag etc.
I think these are around £700

There is also a simple mechanical hydraulic valve that can be used which removes the haldex ecu and overs a varying level of bias up to 50/50.
They can also be supplied with a switch so you can release the drive when using the handbrake / reversing / or to save fuel.
These are around £300.

I have been looking into this quite a bit myself and i intend on stripping my haldex down and designing a part to replace the clutch plates with a solid permanent drive.... so bin all the gismo's and have 50% to the ear all the time.
This of course would make dyno'ing the car difficult etc.

As for which models to use for the conversion.... any mk4 golf 4 motion / r32.. or audi A3 quattro or S3.... just not the Audi TT as the propshaft is too short and the boot floor is totally different.

 

[Rgm racer]

Guys thanks for the replies, in particular Graham great information as always. I could seriously do with you as my neighbour

I have just done my 6th and final track day this year and plan to carry on with the car as it is for my next track season end March-end October. At this stage I am planning to develop car further after next October assuming I feel the same way I do now through next year.

I am basically thinking either:-

1. GT30 and stroker, still FWD.

2. GT35 and stroker, still FWD, probably mad but quite maybe mental and mad could be fun

3. As number 2 but convert to 4wd, hence reason for post.

Concerns are, will I regret throwing more power at FWD only, on other hand will I be disappointed with 4wd/conversion and then regret having to carry extra weight??

I suppose to sum up I guess option 1 really max way to go if staying FWD, option 3 will give best power and decent traction compromise whilst if just want to go mad go option 2 which will be a handful to say the least in terms of getting power down but will also have serious power to weight ratio??? decisions, decisions, decisions.

If yours is up and running through next year I would love to see it/come out with you to get an idea of what to expect and a chance to go out in a big power 4wd Leon such as yours would help make my mind up one way or the other.

I think in hind sight I am of a similar mind to you in that if I could turn clock back 4 years or so I would probably have bought a 4motion like your other toy or an S3 [or something jap] but I have now spent so much money, time and effort on this car I'm not really looking to start a new car project from scratch , who knows that may change next year but think not at the moment?

So if using either of the various methods of controlling Haldex , would it not matter whether system was of the proactive or reactive type in the first place? So for example either could be set to give permanent 50/50 drive when wanted and switched off all together if wanted?? I'm thinking it might be more economical driving to and from events with it off but on other hand if it kept things more simple I may well prefer to have it just set permanently to 50/50 all of the time if that's possible?

 

[grahams81]

Guys thanks for the replies, in particular Graham great information as always. I could seriously do with you as my neighbour

I have just done my 6th and final track day this year and plan to carry on with the car as it is for my next track season end March-end October. At this stage I am planning to develop car further after next October assuming I feel the same way I do now through next year.

I am basically thinking either:-

1. GT30 and stroker, still FWD.

2. GT35 and stroker, still FWD, probably mad but quite maybe mental and mad could be fun

3. As number 2 but convert to 4wd, hence reason for post.

Concerns are, will I regret throwing more power at FWD only, on other hand will I be disappointed with 4wd/conversion and then regret having to carry extra weight??

I suppose to sum up I guess option 1 really max way to go if staying FWD, option 3 will give best power and decent traction compromise whilst if just want to go mad go option 2 which will be a handful to say the least in terms of getting power down but will also have serious power to weight ratio??? decisions, decisions, decisions.

If yours is up and running through next year I would love to see it/come out with you to get an idea of what to expect and a chance to go out in a big power 4wd Leon such as yours would help make my mind up one way or the other.

I think in hind sight I am of a similar mind to you in that if I could turn clock back 4 years or so I would probably have bought a 4motion like your other toy or an S3 [or something jap] but I have now spent so much money, time and effort on this car I'm not really looking to start a new car project from scratch , who knows that may change next year but think not at the moment?

So if using either of the various methods of controlling Haldex , would it not matter whether system was of the proactive or reactive type in the first place? So for example either could be set to give permanent 50/50 drive when wanted and switched off all together if wanted?? I'm thinking it might be more economical driving to and from events with it off but on other hand if it kept things more simple I may well prefer to have it just set permanently to 50/50 all of the time if that's possible?

Yes If only we could turn the clock back mate

I wouldn't really worry about the extra weight as especially most of it is in the rear which would surely create a more balanced car

Another plus for the conversion is the fully independent rear suspension that comes with the conversion....... it's obviously a major bonus as the original Supercopa's used a 4wd shell and suspension but without the 4wd installed.
The supercopa cars weren't that powerful so on there cars having the extra weight of the diff etc I'm sure it would have been a hindrance.
Your going to be running 2-3 times the power of a supercopa so personally i would have thought the positives would outweigh (do you see what i did there ) the negatives.

I'm more than happy to give you a go or take you for a ride mate when mine is finally on the road, hopefully by spring next year. I'll be taking it to Bill's for final mapping and probably take it down to Bridgwater to work some weeks to give it a run out.

Oh and the haldex controllers - the two bottom ones (in the post above) can be switched on and off to run fwd and 4wd. You can also vary the torque levels on them but i think a 50/50 is going to be the best.
Also i'm probably going to instal a switch in mine to switch between 2-4wd, like you say for normal driving to track days etc it's not worth burning the extra fuel / tyre wear etc..

 

[Murdered LCR]

I think haldex with a controller would be enough tbh I don't have a controller on mine yet but its still really good as they are standard I know alot of the R32 turbo boys don't have any issues Gaz who rebuilt my engine runs a hpa gt35 and does 5k launches with a wot box and the haldex is fine

 

[Hullcupra225]

what would a ball park total figure be to convert a LCR to 4wd out of interest?

 

[Rgm racer]

what would a ball park total figure be to convert a LCR to 4wd out of interest?

Difficult to say but would have thought minimum couple of grand if diying it and minimum double [up to 3 times] that if paying someone to do it.