Latest Alfa.... 147jtdm

[Divano Veloce]

To replace my faithful 75TS for the run to work, i now have a 147jtdm...it should pay for itself in 4 years with the improved economy... #littleredtractor

[Citroënbender]

Looks beaut. Sunroof and Bose system?

[Divano Veloce]

Thanks Bender, no sunroof or bose alas.... but low kms and a very nice tan interior. Needs stereo connectivity and egr disable/delete. 3rd gear 60-100 is a blast, as is 4th 100-..... but im thinking a remap may eventually be on the cards ...

[Divano Veloce]

Reading alfaowner.com and have contracted swirl flap paranoia.... and have decided to deflap my cf4 manifold.... purchased gaskets from Holden dealer in Bendigo and am ready to proceed....

[Divano Veloce]

Experience so far and some comparisons to our other tractor – Skoda Octavia 2.0TDI

Air con – I drove the 147 from Adelaide to Castlemaine from ~20 degrees to ~35 degrees and adjusted the fan speed maybe twice.... Its so damn good you don't even notice it. Our skoda blows cold air up your nose while the rest of you sweats. And it gives you industrial deafness. That's if you can get it to do what you want.... And if it works at all...

The 147 handling is a bit iffy... maybe its tired dampers/bushes at 120k kms but this new car review sums up my experience perfectly:

At ordinary speeds it's only the slightly fidgety ride and quickish but not overly communicative steering that gripe. But step up the pace, as you'll want to in an Alfa, particularly one with such a sporting engine, and you're rewarded with deteriorating body control and a mushy-feeling middle pedal.

The steering is over-assisted and the car just wont take a set in a corner.... At higher speeds, especially on rough roads it gets hairy...
However, at 210k kms and original suspension our Skoda Octavia wagon is still bang on. Nicely weighted and responsive steering, takes a set every time, very easy to position on the road, responds very predictably to the throttle and handles poor road surfaces and dirt roads with ease. They Czechs got it right. Its longer and heavier which no doubt helps.
Im interested in how to improve the handling of the 147, however it's an a to b sensible(!) second car, not a project.... But its really not anywhere near where it needs to be.... It bottoms out the undertray on good b roads at sensible speeds..... fark.

Motor.... The Golf 2.0TDI motor in the Skoda with 6 speed box is torquey but needs to be short shifted for any sort of rapid acceleration. Fortunately the box is slick. Above 100kms/hr it's not very interesting.
The JTDm motor is just so much better.... More torque for so much longer.... but the gearbox is slow to shift so it seems most remarkable in single gear bursts, like 60-100 in 3rd. (60-100 in second in the 75 is not quite as much fun....)
This may help to fix it: http://www.alfaowner.com/Forum/alfa-147-156-andamp-gt/315867-how-to-147-stiff-gear-change.html
Maybe Ill tackle the gear shift after the deflapping... but its not a project car....

[Citroënbender]

OEM shocks are rubbish, they'll be your numero uno item to replace. 

[Divano Veloce]

Thats great news! A shame for the first owner who did all those kms on them...

http://www.alfaclubvic.org.au/forum/index.php?topic=17201.msg100881#msg100881

Seems to be a consensus on the 147. All issues fixable.

[johnl]

The 147 handling issues (at least as I identify them) can largely be fixed, or at least substatially improved. All you need to do is identify each specific problem (and there are a few), and then throw enough time, money, and lateral thinking at it.

Semi random related thoughts:

Having lived with them for a while now, I still consider the B6 Bilsteins (front) to be a bit lacking, i.e. not as well sorted as I think they ought to be out of the box (though an order of magnitude better than new condition stock rated TRW front dampers). Even with the stock springs the B6s struggle with high frequency inputs, even of relatively small amplitude.

Corrugated surfaces are the most extreme example of what causes them to lose the plot, though any sharp, abrupt kind of bump can exite the suspension in  manner the damper may struggle with. The deeper the corrugations the worse it is, but the corrugations don't have to be severe. If I had the time and uncommitted $ I'd have the Bilsteins revalved, probably quite a bit stiffer in rebound (my impression is that the B6 damping may be stiff 'enough' with low rod velocity damping, but too soft with high rod velocity damping).

Given my previous experience with adjustable Koni 'Sports' on a diferent car I would have chosen those rather than the non- adjustable B6 (i.e. if I knew then what I know now re the B6 in this application). A consideration at the time was that the B6s were quite a bit less costly than the Konis, and since Bilstein is very highly regarded and user satisfaction generally reported as very high, I went down that road. Wrong track IMO, a bit disappointing really, at least for the front end of a 147.

Oddly, I found the stock rated rear dampers (TRW) to be far massively better than the stock fronts. Ideally (IMO) they could be a bit stiffer, but not as a matter of urgency (as I felt was the case for the new stock rated front dampers, i.e. I couldn't live with how bad they were, at all). My preference, considering my experience with the front B6s, would be to replace the rear dampers with Koni Sport, but this can wait until the existing rear dampers die (though having said this, considering that the B6s are stiffer than the already at least adequate stock rated rear dampers, the B6s may be just fine on the rear end).

In all honesty I feel the stock rated rear dampers work better on my car than the B6 front dampers. It may be (i.e. I speculate) that this could possibly be related to the massive rear anti roll bar I have fitted. I suspect that in single wheel bump / rebound, force is transferred through the very stiff ARB from the suspension on the side that has encountered the bump (or roll motion suspension travel) to the suspension on the side that has not encountered the bump. The speculation goes that in this case it is not only the damper on the side encountering the bump that is working to damp that side, but also to some degree the damper on the other side. Thinking this through, it also seems that the very stiff ARB would also cause both springs to in different degrees resist a single wheel bump / rebound moment (imagine a hypothetically infinitely stiff ARB, what would that cause in this regard?). The affect of the stiff ARB on double wheel bump / rebound stiffness is at least a lot less.

Something I would dearly like to do is to substantially increase the caster angle, which would have a number of positive benefits, but also cause a significant problem. This problem is an increase in bump steer, which would also manifest as roll oversteer (probably a bigger issue than bump steer per se, having encountered this side effect of increased caster on my old Accord, which I did fix by relocating the steering rack downward by several millimeters, not really possible with the 147 steering rack). To significantly change the 147 caster angle would be quite difficult, and then rectifying any consequent bump / roll steer problem arising could also be very problematic.

Sorry for rambling on...

Regards,
John.

[bazzbazz]

I have believed for a long time the 1.9D 147 is the pick of the litter, same horsepower as the petrol but with extra 120nm of torque, just put your foot down and it PULLS !

Add to that 6 speed box and the ability to go from Brissy to Sydney on a single tank , , , , what's not to love? (and I hate diesels) 

[Divano Veloce]

Thanks everyone. The 147 was to replicate the role of the skoda rather than replace the 75 (nothing could). So comfort, safety, efficiency and cost were the the drivers. Ultimately we bought the car for the motor, only to find out on the drive home that in terms of handling it was not like any Alfa I'm familiar with. Its a bit disappointing as the ingredients are there... but it seems that front dampers and anti roll bars should fix it. It now has a Holden inlet manifold gasket so why not install a Holden rear ARB...
Otherwise, I have an opportunity to purchase a set of 147GTA ARBs. Will these be enough increase in roll stiffness?

In other news.... the dreaded Swirl Flaps are no more...

[Citroënbender]

Stiffness of an ARB is (theoretically) compared by diameters to the fourth power, but as the ability of an ARB to pass on load from one leg to the other increases, you'll get more deflection of other components.

I'd start with just shocks.

[johnl]

CB said:
"I'd start with just shocks."

Yes. Dampers are more important than spring rates (within reason). If the damper performance is marginal then changing the spring rate is at best a waste of time, and may even make matters worse (often...). Changing ARB rate (which most commonly means stiffening it) is somewhat less affected by damper performance, but again the effort (money / time) would be far better invested in damper improvement first because no suspension will ever work acceptably if the damping performance is poor.

"Stiffness of an ARB is (theoretically) compared by diameters to the fourth power,"

Yes...

"but as the ability of an ARB to pass on load from one leg to the other increases, you'll get more deflection of other components."

What components? And the problem then is?

A stiffer ARB will more heavily load the drop links, the 'D' bushes, the chassis locally where the 'D' bushes attach. If these are up to the job then what issues arise?

A stiffer ARB will take load off the springs in roll and single wheel bump loading. In single wheel bump, some of the bump loading will be transferred from the spring encountering the bump, to the spring not encountering the bump, more so the stiffer the ARB.

So with a stiffer ARB, the spring and damper on the side that encounters the bump will be less loaded / deflected by the bump because a somewhat greater % of the bump loading is transferred to the other spring and damper through reduced twisting of the stiffer ARB. So, a stiffer ARB reduces load on the 'bumped' spring / damper while simultaneously it more heavily loads the 'unbumped' spring / damper, but not a lot, and way less than it is loaded when it is on the side that encounters the bump.

Regards,
John.

[Citroënbender]

That was essentially my point; that while I had furnished the means to make an empirical, facile comparison there would be contributory elements which took the result away from the simple ratio of (D1)^4/(D2)^4

Aside from that, your own documented variations are to the "TI" spec suspension which may or may not be similar to that of our man in Castlemaine. EPer would reveal the extent of overlap.

[johnl]

It now has a Holden inlet manifold gasket so why not install a Holden rear ARB...
Otherwise, I have an opportunity to purchase a set of 147GTA ARBs. Will these be enough increase in roll stiffness?

DV,
A reason to not fit a Holden (modified front) ARB is that this conversion is far from a simple bolt-in swap. The Holden bar needs a lot of modification to its' shape, and strong custom brackets need to be designed and fabricated. If you are confident that you can do these things, then go for it. 

Having fitted and lived with a very 'robust' rear ARB, IMO the stock rear ARB (only a wimpy 14mm OD) should be replaced with another at least as stiff as you are likely to purchase (or adapt / make). My modified Holden Rodeo bar is significantly thicker at 20mm OD than the aftermarket 147 rear ARBs that I've seen advertised on ebay (18mm), though the 'arms' on my bar are 3cm longer than standard, which will deduct from effective stiffness.

So, my rear bar is a LOT stiffer than stock due to being substantially thicker, but somewhat softened due to longer lever arms. I found an ARB rate calculator on-line and input some dimemsions from the stock 14mm ARB, stock shaped but thicker (18mm), GTA (17mm) and my custom bar. The calculator says:

17mm GTA bar = approx 2.2X stiffer than stock 14mm bar

18mm aftermarket bar = approx 2.8X stiffer than stock bar

My ARB = approx 3X stiffer than stock bar (this takes into account that my bar has the longer arms)

Next time I have the rear ARB out I intend to weld on some new bar ends with multiple attachment holes, so I can try running it yet stiffer...

Regards,
John.