Retrofitting a Q2 to an existing Alfa

thanx for that TB, the gearbox i am looking at has a torsen style diff in it, so its nice to know how the diff tranfers torque!!


Brad...

TB, just when I think I've cracked it you have to go and throw a spanner in the works . I am at least seeing how it works now (and it isn't as mystical as I imagined ), the acceleration/coasting is only the final piece of the puzzle.

Right, I'm looking the T1 diagram and assuming it means that under acceleration the sidegears move to the right, altering the gear tooth angle, thereby changing the tbr. Decelerating, changing the tbr again by moving the other way.

Whereas the T2 does not look to have any sideways movement or if it did would break into pieces. What say you?

Highlighted is the interaction of the gears directing torque when turning left or loss of traction on the left, the gear tooth angle determining the bias ratio.

Here's a description to accompany the illustration on how the outside wheel is allowed rotate faster during cornering, tried finding something more technical, still pretty clear. What I take from this (I'm sure someone will correct me if I'm wrong) is that it will behave as an open differential until the output torque is less than the input ie loss of traction, then it applies torque to the output shaft that requires it, which goes to explain the compatibility with braking from ABS and traction control, the side gears (purple) planet gears (gold) above.


"When the differential housing rotates, the planet gears are rotated around the output side gears. Thus, force is being applied from a planet gear to a side gear. As described above, no relative motion can occur between these two gears because they lock up solid. This means that full force is being applied from the differential housing to the output shaft. This occurs regardless of whether or not the other output shaft has any load (traction).

When the car goes around a corner and one wheel needs to go faster, the force from the faster outer wheel goes *into* the differential through the output gear. Now we have a situation where a force is being applied from a side gear to a planet gear. Relative motion between these two gears is allowed when the force is in this direction.

To summarize the two main characteristics in a different way: Forces between the housing and an output shaft (engine power to a wheel) are directly coupled. Forces between two output shafts (differences in speed between the two wheels) allow the internal gears to rotate.

The real beauty of this design is that these two characteristics are autonomous. Both things can be happening at the same time. Full power can be applied while going around a corner. The wheels are allowed to turn at independent speeds. Full torque can be applied to a wheel even if the other has lost traction. (Up to the equivalent of about 80% lock up). Changes in the situation are automatically adjusted for instantly by the inherent nature of the design. Everything operates in a precise balance.

There is no need to choose a trade off between maximum traction, and the ability to go around corners.

It's also important to note that while this design relies on the friction characteristics of the gear teeth to control its behavior, it *doesn't* use friction to transfer power (like a Clutch Plate LSD). This design doesn't have any more wear than a conventional differential.

The Torsen is probably one of the most elegant mechanical designs in automotive history."


http://www.318ti.org/notebook/diffs/index.html

Sorry for the delay in replying, was busy getting car ready for a track day, and then the trackday day itself.

You could be right, I don't know enough about gear internals to comment further on the diagrams to be honest

..but in practical terms though, after the trackday I can now confirm that the Q2 diff works just fine under braking, I didn't notice any negative characteristics and maybe very slightly improved stability over a standard open diff.
This was with Ferodo DS300 front pads, and DS2500 rear pads, type-R tyres - so a stern workout.
As to whether my new 20mm rear ARB also helped with trailbraking I suspect this may also be the case, but the diff seemed to not cause any problems whatsoever.

I'm almost certain my impression of very slight understeer under trailbraking at the Ring was caused by the fact that my rear discs were very worn and just beginning to shudder.
I had new ones for Fridays trackday.

Cheers,
TB

Originally Posted by Caldo Bollente

TB, just when I think I've cracked it you have to go and throw a spanner in the works . I am at least seeing how it works now (and it isn't as mystical as I imagined ), the acceleration/coasting is only the final piece of the puzzle.

Right, I'm looking the T1 diagram and assuming it means that under acceleration the sidegears move to the right, altering the gear tooth angle, thereby changing the tbr. Decelerating, changing the tbr again by moving the other way.

Whereas the T2 does not look to have any sideways movement or if it did would break into pieces. What say you?

Hi TB,

Nor do I, I'm just saying what I see was on a mission to knowing how it works and hasn't been covered in this thread yet, so it's all good.

My understanding from the design of the T1 is that the side gears would, if implemented (as it suggests in the paper), have different angles on each side. Then, according to thrust, screw towards one side or the other as it were, by doing so the planetary gears using a different angle/bias ratio, looking at diagrams of the T2 itself with the opposing rotations this doesn't seem possible.

Having an equal ratio shouldn't really be a hindrance if it continues to search for grip under braking and after reading your review, hasn't.

One more question to the basics, please:

It looks like as if the standard-diff (part# 95721110) can be replaced in general by the new Q2 unit. This part-number is listed for 3.0, 3.2GTVs (98-05), stronger TDs (1,9) and 3.2 petrol engines of series 156, 147, 166 and GTs.

For "older" models, like GTVs 2.0TB, 3.0 (1995-98), 164 (var.), 155 V6 there is a different part-number (60810912). I took a look at the spare-parts catalogue and it looks quite the same - maybe it triggers the speedometer (for some models). I've been told that the Q2 should fit the gearboxes of all V6 models - wether they are 5 or 6 speed - but up to now I don't have any proof....it still sounds like "should" or "might" fit...

Did somebody already replace this part (# 60810912) by the Q2 unit - or at least: does anybody know if somebody has or tried to replace...

Thanks a lot and KR Martin

Originally Posted by GTV916

One more question to the basics, please:

It looks like as if the standard-diff (part# 95721110) can be replaced in general by the new Q2 unit. This part-number is listed for 3.0, 3.2GTVs (98-05), stronger TDs (1,9) and 3.2 petrol engines of series 156, 147, 166 and GTs.

For "older" models, like GTVs 2.0TB, 3.0 (1995-98), 164 (var.), 155 V6 there is a different part-number (60810912). I took a look at the spare-parts catalogue and it looks quite the same - maybe it triggers the speedometer (for some models). I've been told that the Q2 should fit the gearboxes of all V6 models - wether they are 5 or 6 speed - but up to now I don't have any proof....it still sounds like "should" or "might" fit...

Did somebody already replace this part (# 60810912) by the Q2 unit - or at least: does anybody know if somebody has or tried to replace...

Thanks a lot and KR Martin

Take a look..

Originally Posted by kgb

My german is not very good, but the Q2 diff. fits to the 5 gear-box on the JTDs as well without a problem...as you can see from my pictures that you used in the manual

also there is another pictures that I think is from a friend of mine that has fitted the Q2 to his 164 2.0 V6 Turbo.

On the diesel you can go by just replacing the differential itself, no need of rings and other stuff.

Yesterday we finish fitting the Q2 to a GT 3.2

Q2 in action....

If I am having a new clutch put in my GTV V6 is it worth fitting the Q2 diff?

Will it make a noticeable difference to the handling?

Do i just ask for a Q2 diff?

well,

I in personal opinion...YES go ahead and fit it to your bella.

Yes it will improve handling...during all conditions, accelarating, braking, cornering...wet,dry.

Yes you will feel it.

It will work better if you car has stiffer suspension!

Feel free to ask any question you may have....and read the whole thread ( i think you have already done it)

I'm a little confused by all the Part nos & car types flying around. Can I fit a Quaife ATB or/ Alfa Q2 to my 1999 3.0 V6 GTV 6spd?

Yes.

KGB: When you were retrofiting the Q2, did you remove the gerabox from the engine, or is it possible to change the diff, while gearbox is in the car?

No need to remove the gearbox because the diff is in its own separate casing. You just unscrew the driveshafts from the diff, remove the diff casing with the diff inside, swap crown gear and bearings to the Q2 and put back together.

So this also goes for JTD with 5 speed gear box? As I understud all JTD's have the same Diff casing.

Thanks, if this is true I might be not far away from buying Q2.
But I assume that if you are doing the swap, it's better also to replace the bearings with new ones, since you already have dissasemblled the diff.

Bearex,

My 147 JTD is the old 8v version, same as yours (now it is QVD with 170hp and 400NM)....I have the Q2 with the 5 speed gearbox a new one with 6 speeds will be fitted soon.

But the Q2 will fit easily on your car, yes it is better to change the bearings, but if they are in good conditions and you disassembled them with care and caution you can still use them.

Thanks for the explanation, now it's much more clearer to me.
But now that you have fitted Q2 in your original gear box, you will change it for 6 speed? Does it fit without problems?
I can see that you have gained quite a lot from youf engine - 170HP and 400Nm is quite a big number, as I'm familliar with ordinary chip tuning you get 140 HP and 350Nm. I didn't completlly understood what else did you change to acchieve that high power and torque. Did you replaced the intercooler with larger one?

Have a look at another thread:

http://www.alfaowner.com/Forum/tunin...47-jtd-8v.html (6sp. gearbox into 147 jtd 8v)

About the "chip" tuning a can make my own remaps but I am using the services of Digitaltuning. From what I have come across they are among the best tuners in Europe (world).

Can I fit one to a 1997 GTV 2L T-Spark?

I tried reading through the thread to find out but now my brain hurts.