Red Devil mkII - The Journey Continues

[h100vw]

Rolled the arches at both ends, but it's down to how low you intend to go.

Gavin

[seangti]

I noticed you had: Enkei RPF1 17x8, 35ET which are the exact wheels I want to go. Did you require any rolling or did they fit stock? I know Louis has the 16x7s and they are okay, just not sure about the extra width.

FYI running stock suspension / brakes (for the time being )

Yeah as Gavin said, the guards have been rolled. I also have TT rims which are also 8", though I can't recall the off set. On my other polo that don't scrub either - I haven't tried the enkei on it. I'm not sure how much impact the rolling has had. The current ride height is relatively high (for a "lowered" car), I also had to raise the front a little for the semi slicks as they are a 215/50/17 and just touched the wheel well on the front under compression.

[seangti]

I've been a bit quiet in this thread as the car's been running well and I haven't fiddled with or broken anything, win.

I ran at eastern creek back in February and lakeside timeattack round 1 in early March. The car was faultless for the 2500km round trip to Eastern Creek, Nowra (for work) and back.

As the car is running well, I've got itchy hands so pulled the gearbox out over the Easter break and it's now at NA Autosports having the box opened up for an LSD to be installed. I was planning to run a Wavetrac diff though am being encouraged to consider going a clutch plate diff instead. NA are sourcing prices for me at the moment. I think the Wavetrac will be adequate, I'm aware of the shortcomings of such a torsen diff, so it'll probably come down to the price difference. I know the plate diffs are much better for what I'm doing with the car, though they also come with more maintenance considerations and being clutch oriented, have wear considerations so will need to better understand that too.

[sambb]

I'll be interested to hear what decision you make re the diff Sean. A mate is making the same decision for his RS clio and i'll probably do a 5 speed diff down the track too. I've attached articles by a US suspension guru regarding full race setups for FWD'ers and other stuff on diffs, that might have something lurking in there that helps.

April 2000 suitability of preloaded clutch diffs for FWD

April 2000 longevity of preloaded clutch versus worm drive diffs

April 2000 all the diff types (rear wheel drive angle on it though)

I know he's done some articles where he talks about the effect of traction control on clutch pack diffs. From vague memory it was something about how slip needs to develop before the locking will ramp up, so you need to drive them with the TC off or they won't work properly. Might be worth looking into. Eddy seems to drive his on two wheels - wonder what diff he's running?

[Martin]

I have a Quaife torsen LSD in my Pulsar (dedicated track/race car)
and a Cusco clutch pack LSD (80% locked) in my 350Z

The Torsen diff is just wonderful - does a marvelous job on the track and yet it's easy to park in the pits
I do avoid hitting the curbs to keep both wheels on the ground
Uses normal gearbox oil - no friction modifier - no wear and tear - oil stays clean
All the other guys have welded up their diffs - that has given them some turn in under steer and when parking in the pits it's a nightmare (real problem pushing them also)

The 350Z is a pain, parking and left turns always have chirping from the tires and banging from the diff
Have to use the extra high viscosity oil with the friction modifier
The clutch plates make the oil black
The clutch plates will wear out

For street and occasional track work I would much prefer a Torsen diff

(I'm now running -4.6 degrees camber on the Pulsar!)

[sambb]

My mate in his clio is leaning towards the quaife too for that (more streetable) reason. Out of curiosity Martin is your pulsar set up so that its inside rear will hover in the air through corners?

[seangti]

Big thanks for the input guys. Sam, I'll have a read through those articles too.

The ramp angles on the plate diff have to be quite low (which results is lower bite) for FWD for the reasons Martin mentioned. I was advised the car would still have some inside wheel spin as a result of the steeper angles, plus it makes it more gentle on the engagement and the gearbox itself. I run with traction control off, so that part isn't an issue - I hadn't heard that, but I can understand why it would be a hindrance.

I believe Eddy run a plate diff too nowadays. I vaguely recall he had ran a torsen diff in the past.

Any reason why Quaife over Wavetrac. I really haven't looked much at the others.

[Martin]

Any reason why Quaife over Wavetrac

They are both totally awesome

MFactory also make torsen diffs for a range of cars, they are much cheaper

[Martin]

My mate in his clio is leaning towards the quaife too for that (more streetable) reason.

I really don't like the VAG fake LSD (using the brakes)
Previously I thought that the clutch pack was the best option
Now I am totally adamant it's torsen for street usage
Motorsport can use either - hard core and drifting need the clutch pack

Out of curiosity Martin is your pulsar set up so that its inside rear will hover in the air through corners?

Ok - that's an interesting point

I have not specifically set my car up to do that - but as my driving speed has increased and my setup has changed to go harder - yes, my car does pick up the inside rear wheel - but not big air like the other guys, it's only a fist of the ground

With 60% weight at the front, there are particular corners and speeds where the inside rear wheel will come off the ground - that's just how it is
Even the Nissan GTR LM was picking up it's inside rear

As you go for a stiffer rear sway bar that increases the tendency to pick up the inside rear

It's not necessarily a bad thing (on FWD), it has a subtle/moderate benefits:
-helps put some weight on the inside front (to keep it on the ground - and if you have a torsen diff this is important)
-helps limit weight on the outside front wheel, which reduces under steer

The thing is if you dramatically lower a FWD car with McPherson strut suspension, that wrecks the front geometry
It moves the roll center away from the center of mass and causes more roll (rather than less)
Cars like this pick up the inside rear wheel with big air time
But they also get nasty bump steer and erratic handling

My car has a higher than average ride height on the grid - yet it is ~15mm lower than stock

[sambb]

"-helps put some weight on the inside front (to keep it on the ground - and if you have a torsen diff this is important"

Glad you mentioned that. That's what I could gather too, that to run the torsens in FWD it would help to have that kind of setup to ensure BOTH your fronts were being pressed into the ground to make the diff work properly. My open diff car was definitely way quicker on the tight tracks I'm normally on when set up this way at least allowing me to run without the interference of the TC/power cut.

[grandturismo]

Red Devil mkII - The Journey Continues

Some really great info, thanks for the links sambb.

Sean, I've been tracking both the Wavetrac Torsen type diff with my stage 3 GTI and when I moved to my built engine, giving me about around 100kwaw more, I then installed the VWR clutch plate diff.

I originally chose the torsten type LSD from Wavetrac after researching and was impressed with the engineering and quality of product... BUT torsten differentials only work during acceleration and they also rely on both wheels having a certain amount of traction. This was always going to be an issue moving to more power and trying to extract every valuable second I can out of the car.

I'm not sure if you experience some wheel spin driving hard through certain turns at Lakeside? Particularly out of Carousel?

The clutch-type differential works incredibly well on the track and I found that this section of the track I was getting the power down and out quicker with the change in LSD. Much better than the torsen diff when you want increased acceleration out of corners as it will transfer torque to the wheel with the most grip much more aggressively.

Having said all that, it has inherently brought problems to my gearbox with the added load and power. I'm also checking load angles as you know. I thought I'd mention that as I found I had no issues with the Wavetrac/power combination, in fact comparatively I was only marginally quicker with the same turbo setup, tyres and clutch plate diff. The difference is not huge between them but it's the better diff choice for the track.

The Wavetrac is still a great choice, as is the Quaife (any LSD really) but I'd make sure the clutch plate diff, if u go down that path, is of equal quality and well engineered as it will also probably be more expensive.

[seangti]

Thanks Alan. Yeah I have "one tyre fires" all over the place, even coming down the back past the bridge, that downhill left hander into hungry, lighting up the left in 4th gear at 150-160kph, haha, good for a laugh but quite brutal on the box once it grips as it levels out.

I think I'll make the decision based on price as I'm not chasing outright performance and had planned on a wavetrac from the outset, NA Auto were pulling the crown wheel off y'day arvo to measure so they could lock in some pricing. I now nervously await the phone ringing. Plus I really want the box back in a fortnight so I can try get it back in the car before my holiday. If I don't get it back a fortnight it'll possibly rule me out of June timeattack.

[Water Boy]

I believe the wavetrack/qaife is much nicer on axles and CV's. I have also seen them called TBD. Torque biasing diff.

The plate/LSD can be very violent as mentioned above.

Ive purchased a Qaife for my 02J. Will be a while before I can report back!

[seangti]

I went with wavetrac, it's on the way from the US at the moment and will be installed into the box next week. I'll have the complete box back in the car next weekend, though not yet sure if time will permit to be drivable next weekend... fingers crossed. Though beyond that, it'll be June until I can finish it. let's hope not

The pricing hadn't yet come back for the clutch plate diff, though indicatively was looking to be nearing an extra $1000. The other consideration was the wear rate. Whilst the car doesn't get driving often and wear only occurs when it's engaging, I didn't want to have to pull the box out again in 2-3yrs to replace worn plates. Whilst not a big issue, is still a consideration. I feel with carrying left foot brake during corner exit I can manage some of the shortcomings of the torsen style diffs. Chris Harris did a good video on left foot braking in an older focus RS. Worth a look.

[seangti]

I got the gearbox back last week and installed over the weekend. Another PITA job on the drive shafts and a little getting the gearbox mount aligned, would have been infinitely easier with another person. By way of the gearbox, it's now sporting a wavetrac diff and new bearings and seals. It feels like a newy now, albeit it a little tighter and more precise, really happy with the feel.

By way of the diff, yup, it works I've only had a few in-gear quick blasts, but it locks-up both fronts. It still spins 1st and 2nd as it comes on boost in straight line, there is a slight feel in it working the tyres much harder from left to right, it's really quite nice, grips and goes.