Upgrade / Gearbox Questions

[trippytipo]

I was considering making some upgrades to my Alfa 156 2.5 V6, namely:

Bilstein B14 Coilovers
Q2 Diff
CSC Exhaust

Would like some opinions on these choices and if they are worth the dosh - I would definitely like an improved handling on the car, especially around corners and reducing body roll. While the engine note on the V6 is beautiful, I find it a little subdued. I wouldn't want the fart-y, boy-racer sorta sound though - just an amplification of the already existing music.

Also, when would be the best time do perform these upgrades? I mean, the coilovers would be most labour cost-effective when the tyres are out for whatever reason, etc. Should I also consider doing stuff like replacing the clutch (slipping a little) and rebuilding the gearbox synchros (gear changes are pretty notchy) when I do the Q2 diff?

Lastly, on the topic of gearbox synchro rebuilds - how vulnerable are the actual gears themselves (i.e. teeth et al) to wear and tear? I know the synchros are usually the first to go, but how much abuse can a gearbox usually handle?

Thank you gentlemen!

[colcol]

Do the Q2 diff conversion first, before you HAVE to do it, to replace clutch, you have to remove gearbox, so have the Q2 diff put in, have a new synchro put on second, have all the gearbox checked, while it is apart, have new seals put in, and a new slave cylinder, do this first and worry about the other things later, Colin.

[bix]

Hi TrippyTipo,
A few comments:

• I don't believe the gearbox needs to be removed to fit the Q2 (at least this is what I've heard with the GTAs).
• If you are on a budget, the Eibach pro sport kit are a more economical choice than the Bilstein. The Eibachs were also voted the best price to performance from Auto, Motor & Sport magazin
• If it's body roll you want to improve, then you might look into the Eibach Anti-roll bar kit
• The gearbox can handle quite a bit of abuse. It's normally the second syncro that goes first. If all gears are notchy, then I'd be very surprised if it was the syncros. Perhaps first try some good synthetic gear-oil with the correct spec
• For the v6, I have heard very good reports (increased power and great sound) on replacing the headers for items such as these: http://www.supersprint.com/en/prod-c-7109-5966-7475-manifold__downpipe_kit_stainless_steel.aspx. These are clearly for the GTA although there must be options for the 2.5 - Pretty pricey though.

Cheers.

[Domenic]

If the diff is changed without taking the gearbox out, how is the pinion depth/diff pre-load measured and set?

I'm scared to know who has put a Q2 in their car without having the gearbox removed, and not having the pre-load not set up right, would be a waste of time fitting the Q2 really if the pre-load isn't done. The crown wheel and pinion won't be meshing as they should. Too tight and it wears the gears, too loose and it'll probably strip the gears.

If it was me, when you change the clutch i'd change the diff and get the gearbox inspected and reco'd, just as Colin said. No point pulling the gearbox out to fix it if the clutch is ok, as you won't end up replacing the clutch and then late on it will need to and you'll have to pay twice for the same labour if than makes any sense.

[L4OMEO]

While the Q2 is almost a mandatory upgrade for the larger engines (for both getting the power down and for the longevity of the gearbox) it's not as necessary for the 2.5 which has far less torque to transmit. Also, the Q2 is very tyre sensitive (ie to get the most out of it you need pretty decent rubber - with ContSportContact 3s I found it sensational with full power-down mid-corner pulling the nose in tight, on Kumho KU31s it's merely ok).

Dominic - interesting comments. Little doubt you're more mechanically competent than I am (not hard...) but I was still surprised by these remarks. Frankly, of the literally dozens of Q2 installations I've heard of I don't believe any of them had the gearbox removed to do so (other than where the 'box was lunched). That being the case, either there are lots of Q2s out there not working correctly, or there is a method of properly installing and setting up the Q2 with the gearbox in place.

If you are on a budget, the Eibach pro sport kit are a more economical choice than the Bilstein. The Eibachs were also voted the best price to performance from Auto, Motor & Sport magazin

Co-incidentally, I have a set of Eibach springs and a full Eibach ProSystem set-up (tuned springs & shocks) for sale at the moment, PM me if interested.

Cheers
Rory

[wankski]

If the diff is changed without taking the gearbox out, how is the pinion depth/diff pre-load measured and set?

it's all done with the g/b in situ - shimming only occurs on the one side to achieve proper lash.

the g/b in these cars have a small 'hatch' for the independent access of the diff.

that said, if the clutch is out, then you're talking dropping the box anyway. In this instance - should be done all at the same time, and to inspect the gearset. U might be surprised... these boxes are pretty solid so u may find the gear issues are indeed clutch related.

good luck with it all!

[colcol]

And while you have the gearbox out to do the clutch, put some new seals in and at least check 2nd gear synchro, don't want it to start leaking a week later, and crunching 2nd, Colin.

[trippytipo]

Thanks for all the advice gentlemen! Always learning heaps from you veteran Alfisti.

To be exact r.e. my gearbox, I have trouble getting into second gear and a notchy third gear usually only when it is cold.

Once the gearbox has warmed up, second is pretty normal and the third gear is only slightly notchy.

Will try a change of gearbox fluid to see if it helps and wait till the clutch is due to be replaced before I put in the Q2 diff, so I can do a gearbox inspection and overhaul if deemed necessary by the lord mechanic.

Gonna keep shopping around for more opinions on the springs/coilovers and exhaust - no hurry on those.

[colcol]

Don't leave the Q2 installation too long, when the original diff breaks, it punches a hole in the side of the gearbox, requiring a new gearbox casing, which are as you can imagine, quite pricey, and they don't just break when giving it a fang, they have been known to break when backing out of your driveway first thing in the morning, sounds like you may need a new 2nd gear synchro, and 3rd gear synchro needs looking at, priced some 156 synchros on ebay a while ago, didn't seem too bad, if the car is used on short runs, you can get contamination in the oil, as the nasties are not getting burnt off, take it for a good run, and drain the gearbox oil hot, and put in some good fully synthetic gearbox oil of the right viscosity from your favourite oil company, Colin.

[trippytipo]

Thanks for the heads up, Colin.

Is the original diff a service item like the clutch and timing belt or is it something that can potentially last for the life of the car? I suppose what I'm trying to get at is what is a good mileage/age to have the diff replaced, given that it breaks without warning?

[colcol]

A good time to replace the diff is tommorow or when budget permits, how many klms has your car done? the diff can potentially last the life of the car, but go and have a talk to your Alfa Service Provider and have a look at the disaster when the diff breaks, they usually have broken casings to show customers, Colin.

[L4OMEO]

The diff used in the V6 models of this area was a known and well-documented weak point. Examples have been known to let go from as little as 40,000km, while there are other examples that have done in excess of 150,000km. The lifespan probably relates to how it's been treated, cars driven sympathetically being more likely to last than those driven hard (even if they happen to go 'pop' under moderate load). At the end of the day, if you've bought the car second hand there is no way of telling if your diff is minutes away from disaster or will last a lifetime, regardless of age or mileage.

On the positive side, the diff issue is definitely exacerbated by torque. While I'm not saying it hasn't happened, I have never personally heard of a blown diff that's hooked up to the 2.5 V6.  Just so we're clear I'm not providing any sort of guarantee here   but I think the risk is much lower than with the 3.0/3.2 litre cars, which may influence the decision on if/when you upgrade to a Q2. If I were you I wouldn't necessarily panic. By the sounds of it though you have some other problems with the gearbox itself, and if you were to address those then it's an ideal time to go the Q2 route.

The Q2 will most likely outlast the rest of the car so once installed you should have complete piece of mind. Unfortunately the prices of Q2 kits sourced direct from the UK have risen of late and are around GBP500 + shipping, up GBP50 or more from when I got mine. Shop around and see what you can find. There are plenty of places now with first-hand experience of installing these so you should be able to get a set-price quote.

BTW if you DON'T upgrade, and DO blow up your diff/gearbox, give me a call because I have a 6-speed gearbox with Q2 installed about 18 months ago currently for sale. I'll do you a good deal in light of my 'it should be right' comments above  

[Gotta B Red]

Hi All,
My query seems to follow this thread,and is....
Just how big is the "hole" in the G/Box or bell Housing following diff failure? Are we talking a split or crack,finger sized hole or a fist size hole?
Has anyone on the forum taken any images of the damage? Particularly from the inside of the casing And also any images of the repair as I've read they can be welded but I'm guessing the effectiveness of this repair would be contingent on the size of the deficit.
I also realise that the extent of damage is very likely load or speed related at the time of failure.

Any and all info/advice gratefully accepted.
Cheers,
Andy

[colcol]

If you want to see a failed one, just go to an Alfa Repairer, they usually have a good collection of them, you could weld them, but the casings are not hideously expensive, like its not like its an old Ferrari, i have heard of them failing when backing out of driveways, when the diff fails it punches a crownwheel size hole in the side of the gearbox, Colin.

[Gotta B Red]

Thanks Colin,
I'll try to take your advice with some repairers and see if I can have a look at a failed casing.
The purpose behind the query is based on knowledge of welding aluminium alloys and the distortion due to heat created in the process and the potential for internal structures being damaged in either the failure and or the repair. Internal webs or bearing bosses for example.
Without any re-machining(surface grinding) of surfaces warped or distorted by welding it could present some re-assembly problems and perhaps functional difficulties as well, maybe down to surfaces or edges that were designed to mate/approximate perfectly no longer being able to.
Allowing those precious fluids to escape altogether or leak into a cavity where they're unwelcome.
No amount of gaskets and goop will redeem this problem if it exists.
None of the sellers I've queried thus far that state a Q2 has been fitted have done the procedure pre-emptively all have been reactionary ie after failure of the original.
They do get a little coy when pressed on the repair and how it was effected, if they happen to be dealers they are suddenly overcome by a severe case of ignorance and a before my time/ownership mentality or worse still "Yeah mate they've all had it done"
Hmmm...... really?  At which point I thank them for their time and withdraw politely, crossing their offering off my list.

Cheers,
Andy