Oops : I never even noticed the Tuning subforum until now! This is despite having posted in it! :lol:

I tend to use "new posts" a lot rather than browsing the forums most of the time

----

Have you seen my AO LSD Group test thread Sandy?

http://www.alfaowner.com/Forum/alfa-gta-and-gt/54557-the-ao-lsd-group-test.html?highlight=LSD

If you download the videos you will probably be able to spot the differences in behaviour that I refer to in that thread (and below).

Will have a proper read of your post now Sandy

TB

 

Having had a pax lap in your car at the ring last year I thought it was an understated little gem and applaud your idea of hanging onto a faster version of it
You will defintely need new brakes though! :lol:

Do you know if the Q2 diff can be retro-fitted to existing JTDs?
That would sound like a much better idea than fitting the 2.5V6 diff, which probably assumes a complete paucity of torque.

In my "Group Test" (above) I found the 2.5V6 Quaife diff suprisingly easy to wheelspin under hard corning on a well setup GTA with the same suspension you have (Autdelta sportline coilovers).
I believe Quaife set it up with a fairly conservative limit on the max torque split between the two wheels - its defintely not a torque steering monster and certainly improves traction greatly right up until the point where the inside wheel will spin.
Probably great for the road and is very smooth indeed, completely unobtrusive except for the great traction out of long third gear coeners. Personally I would prefer a much more aggressive max torque split to help with the odd track day.

Obviously in torque terms a 2.5V6 156 will be a hollow chested wimp of a car compared to your planned monster. I would suspect that it is very likely the Q2 diff will have been tuned for the extra torque that the diesel engines produce?

Sandy, did I give you a pax lap at the ring last year?
I remember getting one from you and giving one to others but can't remember if I gave you one.
Well if you were in the car you may remember that I had no torque steer at all on the Ring.

RE clutch type diffs torque steering - I don't know if that is true for all, I believe it depends on how the diff is setup.
I have only driven with one type of clutch type diff, but have tried both fast road setting, and track oriented settings for it.
My Autodelta clutch type LSD hugely reduced the amount of torque steer for road use at either setting.
You will notice no tugging at the wheel in the video I posted above under fairly extreme track use in my car.
I was only at 8 tenths when driving bmoferrals quaife diffed car in the 1st video, but I doubt if throwing the car harder into corners would have improved the diffs performance..
It would just have caused the inside wheel to become unloaded. An unloaded wheel causes the quaife diff to stop functioning and allows wheelspin which would clearly be contained by a clutch type diff.

The drawback of the quaife diff is that it must always transmit a *minimum split* of the torque to a wheel, and unfortunately this is true even if the wheel is unloaded.
This causes the inside wheel to spin up once the the minimum split of torque given to the the inside wheel to spin exceeds the available traction, the diff can't reduce the torque any further and lots of power is roibbed from the wheel that has traction available.
On the otherhand the advantage of Torsen diffs like the quaife diff is that it reacts instantly.

This minimum Quaife diff torque split is hardwired by the manufacturer to suit a specific application - it is my contention that this split (called the torque bias) is way too conservative with a 2.5v6 diff.
I would happily trade a larger torque bias for some extra torque steer..


If you are talking 350lb/ft - then is a pretty serious wedge of torque!
Second gear in my car is pretty wild on road tyres and even on track with Pilot Sport cups I find 2nd gear is pretty extreme under cornering - quite difficult to meter out the max power since you have an excess of torque compared to available grip. I often choose to use third instead and rely on the torque - easier on the car too.

The reason I mention this is that I believe the JTD gearing is pretty low and I suspect 2nd in your JTD box will be pretty useless and result in instantly spectacular tyre shredding
This mightn't be a problem - third might be the only gear you ever need :lol:
The situation might be worse for you than me though, since I have max torque at 5000 rpm, you probably will have 350lb/ft at 2000 rpm or so :lol:
You surely will need an uprated clutch too...

About wet weather performance and diffs - I am sure either diff will hugely increase straight line traction in the wet.
I was VERY suprised at how much less the traction control light came on when I first had my fast road spec AD diff fitted and it made a huge difference on wet track days.
I haven't driven a Quaife diffed car in the wet though.


One other thing is the durability of the diff and the gearbox itself at that torque level.
I have heard of cases of highly tuned supercharged GTAs from diffeent tuners blowing both Quaife and clutch type diffs at around that torque level level (obviously much higher power though).

I wonder how the standard JTD driveshafts will hold up, especially with the lower JTD gearing?
Defintely don't lower your car too much which would increase the strain on them.
(I'm curious to see how long my new ones will last )

AO member "Adie" (ahmotorsports) sells clutch type LSDs and uses them for racing, he gave some helpful info on this thread and might be worth talking too

http://www.alfaowner.com/Forum/lfa-33-sud-nd-sprint/44026-to-lsd-or-not-lsd.html

Hope some of this rambling can usefully be unrambled!

TB

 

Cheers for the comments I'll check the vids tonight, Adie was one of the people I spoke to regarding LSD, dropped him a few emails over christmas, he suggested rather honestly that the Quaife might be better suited for my purpose I should probably get on the blower and get the full low down, I guess he has rather aggressive setup for racing etc. but once he starts talking preload and ramp angles etc, its like 'whoosh' right over my head :lol: I just want it to work when I put my foot down with as little grief as possible.

The Q2 reviews have been pretty good but at the moment my dealer can't help me with a number or a price but considering how Fiat/Alfa are on parts cost vs aftermarket I can't see it being cheap.

Regarding the peak torque I don't think it'll be an issue, its just not really how you drive it, well how I drive it, I drive my JTD in the same way as I'd drive a petrol, using all the available revs to peak power in each gear, flooring it at 2k is just not really done much once on the move, I typically don't do a lot of standing starts, I'd imagine you're asking for a broken gearbox with that sort of behaviour, its on the move when in higher gears with higher revs I want extra, don't think the car is ever below 2500 then and the torque has already dropped off. Looking at zbrsqzjk graphs I'd probably be looking 240-300lbs through the usable range.

I am going to test another remap on the car in a couple of weeks, my Angel map provided a useful improvement over stock with approx 23bhp/33lbs extra at the peaks and a good 20-30lbs through the range I was interested in, the next step is a similar bump again by all accounts so I will see how the car responds before splashing out on turbos and intercoolers but it will probably re-affirm my need for an LSD at the very least.

I guess I should buy a serial port for my laptop and see if I can monitor inlet temps like I could on my GTA will be useful info when it comes to next step deciding upon and testing intercooolers.

 

Still not really any clearer on what the advantages of a clutch type diff vs torsen might be, as the Q2 diff is quite cheap I think thats the one for me, no many companies could tell me what would fit a JTD anyway, Kaaz probably the most reasonable in that they would allow me to have one (for a 156 2.0 (932), TS probably) at a discount to inform them and allow me to send it back if it didn't work which is much better than Quaife.

From what I can see the Q2 diff is a torsen diff like a Quaife ATB will these perform the same? I have read a lot of good stuff about Kaaz seems like a few Jap motor tuners like to use it for its progressive action, would be nice to fit all these different offerings in turn and go out for a blast, if I could chnage the diff myself it would have been an interesting proposition.

Seems most aftermarkt LSD are around the same price which is the 650-700 mark + VAT and then the Alfa one is 200+VAT (if it is indeed the right one)

 

I'll keep an eye on this, I was looking at the Autodelta Torsen LSD for the 147 the other day, my car has a LOT of trouble getting it's power down, dunno if this is due to the dampers at the front being too soft or weight over the front wheels not being enough to keep the front end down (it just bounces if I give it too much torque on launch). Accelerating through a tight corner creates **** loads of traction control stuff going on and I just don't seem to be able to keep it clean whilst using all the available power. I haven't done a lot to the car but it still manages to loose traction at the front and spin momentarily when I change into 3rd at 7K in 2nd.

 

Sandy I'm pretty sure the Kaaz diff is a clutch type diff like that sold by Autdelta.
Maybe I am misreading your post but I got the impression you thought it was a torsen diff (like quaife).

Kaaz are one of the biggest names in clutch type diffs, I wasn't aware that they did Torsen diffs at all but (cough) have been known to be wrong before! some quick Googling would seem to back me up though

The Q2 diff sounds attractive for your needs - a diff optimized for an Alfa diesels driving characteristics.
Quieter and Lower maintenance, although I am not sure how long before clutch plates need tweaking (10's of thousands of miles at least I'm sure before their level of differentiation tails off).
Would be interesting to see what figures Adie indicates for maintenance of their APH Motorsport LSDs.

I don't know if the Q2 diff is Quaife or not, maybe give Jwyatt a PM and he might use his special resources
In any case I imagine they have the same characteristics in general, but obviously any LSD can be optimized for different levels of sporty driving. Clutch type diffs can be tweaked (by a knowledable person) after purchase though by just reorienting plates, whereas I believe tosen diffs can't.

Cheers,
TB

Still not really any clearer on what the advantages of a clutch type diff vs torsen might be, as the Q2 diff is quite cheap I think thats the one for me, no many companies could tell me what would fit a JTD anyway, Kaaz probably the most reasonable in that they would allow me to have one (for a 156 2.0 (932), TS probably) at a discount to inform them and allow me to send it back if it didn't work which is much better than Quaife.

From what I can see the Q2 diff is a torsen diff like a Quaife ATB will these perform the same? I have read a lot of good stuff about Kaaz seems like a few Jap motor tuners like to use it for its progressive action, would be nice to fit all these different offerings in turn and go out for a blast, if I could chnage the diff myself it would have been an interesting proposition.

Seems most aftermarkt LSD are around the same price which is the 650-700 mark + VAT and then the Alfa one is 200+VAT (if it is indeed the right one)

 

Hi Ghosty,

Autdeltas LSD is defintely a clutch type diff, not a torsen diff like the quaife diff.

The short wheelbase of the 147 would mean that it suffers much more from weight transfer under hard acceleration compared to a saloon (changes direction quicker though as compensation ).
Better dampers would defintely help, as indeed would an LSD.

Wheelspin changing up to third in 1 .6? (in a straight line? )
I can't do that in my car! :lol:
You aren't revving on up-changes are you?

The fitting costs would be 4-6 hrs labour on top of the diff itself.

Cheers,
TB

I'll keep an eye on this, I was looking at the Autodelta Torsen LSD for the 147 the other day, my car has a LOT of trouble getting it's power down, dunno if this is due to the dampers at the front being too soft or weight over the front wheels not being enough to keep the front end down (it just bounces if I give it too much torque on launch). Accelerating through a tight corner creates **** loads of traction control stuff going on and I just don't seem to be able to keep it clean whilst using all the available power. I haven't done a lot to the car but it still manages to loose traction at the front and spin momentarily when I change into 3rd at 7K in 2nd.

 

Yup the Kaaz is a clutch type. I am just blabbering in the post as i don't know if I'd be missing out by going for one type over the other, ultimately either type would be an improvement over the electronic option, fingerscrossed the el cheapo option from Alfa is correct and should be sufficient.

 

Wheelspin changing up to third in 1 .6? (in a straight line? )
I can't do that in my car!
You aren't revving on up-changes are you?

Yup, it's not total wheelspin it's more of a scrabble for grip, it definitely loses traction. I tend to change gear pretty quick when i'm pushing it, stamp on the clutch change gear and let off the clutch without a real drop in revs, could this attribute to this? (and the death of my clutch if im not careful )

Why rear dampers?

 

I had said "rear dampers" just to indicate that anything that slows the weight transfer from front-to-back under accleration will help avoid the scrabble for grip on a fast upchange.
It sounded like the lurch due to the sudden reapplication of power was raising the nose of the car and thus losing traction.

Stiffer rear dampers will slow this down.
Stiffer rebound settings on the front dampers would also help too (I had edited my post to just "better dampers" while you were replying )

About your quick gearchange, it should be okay as long as you aren't actually applying power during the upchange. You would hear an engine "slurring" noise as the revs raise when you put the clutch in if you are too slow in releasing the accelerator.
This would be hard on your clutch for sure!
You probably aren't doing it but some people don't notice in the heat of the moment.

Obviously the quicker the upchange the harder it is on the gearbox too, a fact that has recently come home to me
Perhaps my obsession at one point in getting gearchanges physically done in 0.2 of a second for a few track days wasn't my cleverest move. In conjunction with some (fairly evil) engine mods I suspect it meant I recently had to get a new gearbox after 42000 miles.

I'm sure you can take more extended liberties with a 1.6 though.

Any diff would make a huge differnce to how early you can apply the power out of a corner.
Personally I would turn of the traction control anyway on track, it actually helps you learn throttle control, as well as being faster.

Cheers,
TB

Yup, it's not total wheelspin it's more of a scrabble for grip, it definitely loses traction. I tend to change gear pretty quick when i'm pushing it, stamp on the clutch change gear and let off the clutch without a real drop in revs, could this attribute to this? (and the death of my clutch if im not careful )

Why rear dampers?

 

I'm planning on going for the KONI FSD damper setup with eibach springs. From the reviews I've read on other forums they seem and almost ideal balance of comfort and sportiness.

Maybe look at ARB's and a strut brace as well.

I'll do it a stage at a time to better evaluate affects of the various bits I put on.

I think the scrabble for grip is down to the crappy oem dampers on my car.

 

I forgot to say that Lowering will make a big difference too!

Dampers just slow the weight transfer, but lowering the centre of gravity has a more fundamental effect to the actual amount of weight transfer. 147's always seemed a bit high to me personally at standard ride height.

Will be interested to see how you get on with the FSD dampers

Think you are definitely right in termsof bang per buck to sort the suspension before the differential.

Cheers,
TB

I think the scrabble for grip is down to the crappy oem dampers on my car.

 

For sure before any mods to increase power, suspension and brakes will make your car much quicker on the fun stuff.

 

Seen as I've been through this on a previous car:

Go with a torsen diff if you can, it is a much nicer thing to have on the road.

I was OK until around 400@wheels, then the car started to chew through torsen diffs. Switched over to a Kaaz (plate type) and the breaking stopped, unfortunately the car was not much fun on the road - pottering around it would clunk and you could feel the car jump sideways. Car parks were always amusing as people looked over at the car with a mechanical bang, bang noise eminating from it.
As soon as you were on maximum attack the diff behaved impecably, it simply did it's best to put the power down smoothly, it was just a pain 99% of the time when driven normally.
In my experience the torsen type are fine where both wheels are in contact with the road, you are running road tyres, are not doing drag racing starts, and aren't running stupid power. From memory I was OK with around 360bhp & 310lb/ft at the wheels, add another 80 onto these and bits of metal get upset quickly. The Kaaz even seemed to cope OK with airborne moments, which is more than can be said of the bolts that held the diff casing together

 

Hi Robertio, what type of car was it that you fitted the KAaz diff to?

Sounds like your diff was set to a fairly race oriented spec, I doubt if most non enthusiasts would notice anything funny about my diff for day to day use.
A quick takeoff at a 90 degree left turn might cause a momentary slight awkwardness but thats about it.

Cheers,
TB

 

It was a fairly harsh diff I fitted - a diff let go on the dyno, so a fresh one was fitted along with the next engine, ran it in, mapped it and drove down to Shakespear County Raceway and the diff started whining. First run on the quarter - crept off the line, into second and put my foot on the floor, just as I grabbed third there was a loud clunk followed by traditional metal on metal noise. Large shock through the car shook a cracked apex seal loose, so lost compression (and therefore power) through 3rd and 4th, crossed the line with a 12.6@121mph (2.5sec 60')and it was time for another engine and diff, grrr. Decided that I'd be better to put in a diff that would last more than a week, hence the Kaaz (nicknamed clunky for obvious reasons to anyone that heard the car moving around).

The car was my old RX-7, a brief clip of me running it at TOTB last year on another dead engine (killed this one at Knockhill, running in Time Attack) before I admitted defeat and sold it.

 

Looked pretty rapid!

 

well hi there i just order the Q2 diff which is about £280 just the part from alfa it self but there a back log of orders of them and it the gear type diff not plate type so it does not wear any plates out. it fit in the six speed box i think it also fit the standed 5 speed box (need to check that)

 

Lots of info regarding the Q2 retrofit in this Thread

 

That Q2 thread is very interesting - I can't believe the price! I wonder who is making them for Alfa (I don't think it is Quaife but might be wrong) - whoever it is, they are likely to get some bumper orders when this news is widespread. A LSD is probably the best single upgrade to make to a powerful FWD car.

As to plate vs clutch type, the basics are that a clutch type will have better characteristics in most respects for performance driving, and can be tuned, but it is also more complex, expensive, and requires maintenance as the clutch plates wear out. They also produce some unwanted characteristics such as noise, and need the right oil/additives to work right.

Gear type torsen diffs (Q2, Quaife, etc) are totally maintenance free, and will last longer than the rest of the car, on whatever oil you use. They are slightly below the clutch type for on the limit/track driving in terms of characteristics but still a million miles better than an open diff. I would expect them to cause more torque steer than a clutch type if you drove one-handed. But there are no weird noises or appetite for expensive oil, additives, clutch plates, and adjustment. Unless driving a focused track beast like TB's I think they are the better real-world choice but we all have different needs. I'll be fitting one to my car along with better dampers and a strut brace at some stage (and possibly a remap/filter). Springs, ARB's, ride height etc can all stay the same - it's a road car after all in my case...

 

I wonder who is making them for Alfa (I don't think it is Quaife but might be wrong)

It's this company, initially owned by Bosch. It has changed some owners and names since. Now it belongs to JTEKT Corporation. This is their full history.

 

Will use this thread for a question.

Anybody runing KAAZ 1,5 way diff in a fwd alfa?
I'm changing my q2 for something more track oriented (ahm diff, kaaz, autodelta....)
I have some info about AHM and AD, but not much about kaaz?

 

Will use this thread for a question.

Anybody runing KAAZ 1,5 way diff in a fwd alfa?
I'm changing my q2 for something more track oriented (ahm diff, kaaz, autodelta....)
I have some info about AHM and AD, but not much about kaaz?

I already have q2. I think ahm or kaaz will be my choice.

 

go for the quaife :thumbs:

 

It's really not a step up from q2...
Some say it's the same, some that it's a little better. I read all of Trailbraker's posts about AD 30% lsd and something like that is for me

 

I didn't think the AD is a quaife unit?

 

It's not, AD is clutch type