B6 bliss...

[johnl]

As some with good memories might recall, when I bought my 147 it needed new dampers all round. I quickly fitted four new 'standard spec' TRW dampers. These were adequate on the rear end, but complete rubbish on the front, barely any better than the old ones that came on the car (that I tossed as worn out). I obviously needed something much better, at least on the front of the car.

Anyway, after much research it became obvious that the only two real possibilities were going to be either Bilstein B4 ('standard') or B6 ('sports'). I really wanted the B6, but only really wanted to pay for the B4 (and certainly didn't want to pay the price for the Koni option...). Eventually I went with the heart and ordered a pair of B6 front dampers, which arrived a few days ago, and do not regret it at all.

I'd read a lot of people online saying that the B6 is way too harsh for a DD (which slightly worried me about my choice), but now having them on the car I beg to disagree. At least for me (and sensitivities differ), they are everything I was hoping they would be. Sure, they're stiffer, but that should be expected, and it's a good thing. Despite being stiffer, which you can easily feel, they are actually less 'harsh'. The suspension is much better controlled, giving a feeling of 'solidity' that I do not find uncomfortable, indeed a lot less discomforting than the 'harshness' of the softer spec dampers. I think much of the harshness of the standard spec dampers has to do with a near fatal lack of rebound stiffness, which could be easily felt as floatiness and in stark relief when traversing speed bumps, when the front suspension would just soggily compress, then crash to full droop on the downward side of the hump, even at barely more than walking pace.

Now, the B6 dampers handle speed bumps almost as if the hump wasn't there, the car just goes up and over and down the other side, with zero floaty sensation, very controlled. And, it just gets better. Steering is sharper with improved (a lot) steering feel, handling is better, body roll more controlled. The car feels so much more a stable platform. Directional stability is way improved, yet changes direction much more nimbly. The TRWs completely lost the plot on corrugated roads, not the B6s, they handle corrugations so much better (though not utterly perfectly). The suspension makes less noise...

So, that's the front end. The rear TRWs behave much much better than the front ones did, yet at some point I can see a set of rear B6s going on the car, after the TRWs kark it (they're not so bad that I can justify changing them just because I feel like it). Seeming to help the rear dampers is a much stiffer rear ARB (20mm), which I'm guessing is so stiff that in single wheel bump and rebound say on the right hand side, that it tends to transfer force from the right side to the left side, so to some degree the damping action of the left side damper is also damping the right side suspension(?), and vice versa for single wheel bump / droop on the left side. This might be wrong, but the rear end does feel more controlled with single wheel bump / rebound than it does in double wheel bump / rebound, when the ARB does nothing...

If anyone is interested in Bilstein dampers, then I highly recommend Squadra Sportiva in Germany (and I have no connection other than as a customer). I paid about AUD$340.00 for the pair of front B6 dampers, including post (much better price than I found anywhere else). Took 19 days from dispatch to delivery, not too bad.

Regards,
John.

[105greg]

Thats a very good explanation.  I am now at war with my wife about the benefits of bilsteins .    Why does she not get it.    Oh well back to work and justify the expense.   Any second hand ones about. 


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[johnl]

My wife was very understanding (maybe 'tolerant', or 'resigned', or 'long suffering' are more descriptive...), though a bit confused as to why on Earth I'd want to be ditching brand new dampers...

The thing is, now I enjoy driving the car, whereas before it just gave me the proverbials every time because the front damping was so atrocious. Now it feels like a proper sports car, with lively and responsive handling as it should have had from the factory. Why did Alfa drop the ball so badly with the front damping calibration? The 147 is obviously a good car trying to get out, it just needs some help...

Lets see what's next on the wish list; change the dreadful CF3 exhaust manifold (and associated pre-cats) for a CF2 manifold from a 156 (longer primary pipes and no pre-cats), stiffer bushes for the rear lateral control arms (I can feel the stock ones squishing around), make a better less sloppy gear shifter (with no squidgy plastic parts), and one or two other things...

Regards,
John.

[bazzbazz]

Lets see what's next on the wish list; change the dreadful CF3 exhaust manifold (and associated pre-cats) for a CF2 manifold from a 156 (longer primary pipes and no pre-cats)
Regards,
John.

Worked out yet how your going to stop the Engine Management from lighting up without the pre-cats yet?   

Baz

[johnl]

Worked out yet how your going to stop the Engine Management from lighting up without the pre-cats yet?   

Baz

Baz,
I don't know for certain that this won't be an issue. However, research online (i.e. trawling Alfa forums) strongly suggests it won't be. There seem to be plenty of people OS who have performed this modification with no resultant engine management problems (appears a reasonably common thing to do on the 147 over there, i.e. Britain and Europe).

Apparently the main cat alone is sufficient for the third lambda sensor to give readings acceptable to the ECU. Of course the pre-cats have no affect on the readings from the two primary lambdas, being located before the pre-cats.

From what I can gather, the pre-cats are there to heat up quickly (being so close to the engine), more quickly than the main cat (being a lot farther away from the engine). This allows emissions to fall within parameters more quickly, arguably more of an issue for cars that live in a cold climate than is the case for Australian delivered cars. There appear to be quite a lot of cars that have passed the routine British and European emissions tests with the pre-cats removed, so long as the test isn't performed with an engine not yet up to temperature (though I haven't read of any car having failed the test due to it starting with a cold engine).

Owners of cars with the pre-cats removed and the 156 manifold replacing the 146 manifold, report noticeably improved "pick-up" and drivability, which suggests some increase in lower rpm torque (and thus lower rpm horsepower). How much I don't know, the web isn't flush with dyno printouts for the TS engine. It's probably not a large lump of torques or horses, but reportedly it makes a significant difference.

I've also been corresponding with the guy I bought the Bilsteins from (an Alfa enthusiast having owned quite a few it seems), and his opinion is that the TS engine in the 147 (and in the later 156 when pre-cats were fitted, but pre JTS) feels "emasculated" compared to the TS engine in other earlier cars. The main difference is the shorter branch manifold and the pre-cats underneath (in the downpipe). This accounts for the 5hp quoted difference between pre-cat TS and non pre-cat TS engines, but from what I'm told it feels like a bigger difference, which implies a fatter chunk of torque below peak power.

That the pre-cats might be restrictive is not surprising. The primary branches on the 147 manifold are also quite short, something that would be good for high rpm power (they are so short the engine may never actually ever see the rpm at which the engine 'comes on the pipe', as two stroke tuners say). However, short primaries are not good for the sort of rpm in which most of would spend 99% of our time. Longer primary pipes would be a good thing for a road car engine. Even the 156 primaries are probably a bit on the short side, but significantly longer than on the 147 manifold.

Oh, and to fit the 156 manifold also requires fitting the 156 downpipe, which apparently requires some minor modification to fit the 147. The 156 manifold doesn't have provision for lambda sensors, nor does the downpipe, so lambda fittings need to be welded into the forward end of the downpipe.

Regards,
John.