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Discussion Starter #1
I'm considering fitting/having fitted some stiffer ARBs to make the car less rolypoly in the corners on my 159 2.4 SW.

I guess the obvious is a set of eibachs which seem to be the ubiquitous upgrade option.

Does anybody have any feedback or useful experiences with these/others/this sort of thing?

cheers
 

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Discussion Starter #4
If you get an Eibach kit, throw the pu bushes away and get powerflex...the eibach bushes and grease are ****e.
See here:
http://www.alfaowner.com/Forum/alfa-gta/426674-eibach-anti-roll-bars-3.html#post16644146
hmmm ok - I'm not a fan of any PU bush but if i have no choice then I'll maybe powerflex. I'll consult my garage and go with their opinion on the mattery I think.

Glad to hear generally positive feedback so far.

Any impact on ride quality? Standard springs and dampers atm.
 

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Same answer as above, better road manners & massive improvement on standard.
 

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Don't fit plastic bushes. the rubber is there for a reason. I'm sure your upgrade is not to make the ride worse.

But turning to the anti roll bars you first have to establish what 'outcomes' you are looking for. The 2.4 diesel is a very heavy lump and you want to try to get the car to turn in. The original setup is designed to understeer by default (which isn't hard with a 2.4 also trying to send it straight on). So, to get less understeer you need a stiffer rear anti roll bar. This will keep the rear level while the fronts are trying to allow as much rubber as possible to steer it around the corner. If you stiffen the front anti roll bar it will lift the front inner wheel and not go around the corner.

Personally I would soften the front springs to make the front tyres to grip much more. I've done it on mine and now have a neutral towards oversteering car. But I don't have that impossibly heavy diesel in mine!
 

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Discussion Starter #7
Don't fit plastic bushes. the rubber is there for a reason. I'm sure your upgrade is not to make the ride worse.

But turning to the anti roll bars you first have to establish what 'outcomes' you are looking for. The 2.4 diesel is a very heavy lump and you want to try to get the car to turn in. The original setup is designed to understeer by default (which isn't hard with a 2.4 also trying to send it straight on). So, to get less understeer you need a stiffer rear anti roll bar. This will keep the rear level while the fronts are trying to allow as much rubber as possible to steer it around the corner. If you stiffen the front anti roll bar it will lift the front inner wheel and not go around the corner.

Personally I would soften the front springs to make the front tyres to grip much more. I've done it on mine and now have a neutral towards oversteering car. But I don't have that impossibly heavy diesel in mine!
My thoughts regarding the ARBs were along the lines you mention.

I have seen that some are adjustable depending on which hole you bolt it to the car with. My idea was to have the ARBs set stiffer at the rear than the front (under the direction of my garages advise so I don't wrap it round a tree....)

I am not keen on laying out for the money to change my suspension because its a big cost and I like my ride how it is. I take your point on the softening the front springs but I find the nose dives quite dramatically under braking so I don't want to increase this even more (as you say, heavy diesel lump)

Would I be correct that my idea of stiffer ARBs all round, but set stiffer to the rear than front should achieve the desired affect in your view?

Agreed on the bushes, not interested in PU/plastic ones. I got the impression from goremohekan that the bushes it would come with would be PU or is this just an option? I'd rather rubber over PU.
 

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The 2.4 diesel is a very heavy lump and you want to try to get the car to turn in
Does anybody know how heavy? The TBI has one less piston and presumably an alloy block but surely these alone can't weigh that much less, especially if TBI has steel liners?
 

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Discussion Starter #9
Does anybody know how heavy? The TBI has one less piston and presumably an alloy block but surely these alone can't weigh that much less, especially if TBI has steel liners?
carfolio reports a 200kg difference in kerb weight between a 2005 2.4JTDm saloon and a 2009 1.75Tbi saloon. 1430kg vs 1630g respectively.
 

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Does anybody know how heavy? The TBI has one less piston and presumably an alloy block but surely these alone can't weigh that much less, especially if TBI has steel liners?
1750tbi in the Brera/159 has a steel block, very similar to Twinspark or 1.9 JTD.
 

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1750tbi in the Brera/159 has a steel block, very similar to Twinspark or 1.9 JTD
Wow - so now even more confused where the weight differences comes from - can't be much significant difference in the front end weight (maybe 10kg or so but the washer bottle weighs 6kg when full) so 200kg must mainly be from the trim and fittings which are more evenly distributed - confused.com?
 

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They put the car on a weight reduction program around 2008 and I think they managed to strip about 70kg out of the car across the whole engine range. It could well be that the later models have a lower spec - factory weight figures are without any optional extras.

The 2.4 is noticeably heavier at the front end than a 1.9, its got 25% more engine for starters. F40 box feels a lot heavier than the M32 as well.
 

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Discussion Starter #13
Wow - so now even more confused where the weight differences comes from - can't be much significant difference in the front end weight (maybe 10kg or so but the washer bottle weighs 6kg when full) so 200kg must mainly be from the trim and fittings which are more evenly distributed - confused.com?
dont see the confusion.....1.75TBi has four cylinders and is petrol and the 2.4JTDm is five bigger cylinders and diesel. Diesel block generally heavier duty due to higher compression forces. Turbo maybe bigger, bigger intercooler, radiator too I suppose....20% less material need (sort of) for fewer cylinders, and also less steel needed in the block and bits because doesn't need to be as strong.

I think the car also went on a diet around 2008 from the quoted 2005 weight and lost maybe 80kg or so.
 

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But the extra middle iron cylinder in the diesel is only a bit of crank, a piston and a slice of alloy head which would only weigh say an extra 10kgs in the 500kg front end weight. Everything else is pretty much the same except possibly the gearbox which may add a few more kgs. So not really a huge heavy perkins tractor diesel and box we're talking about when comes to comparing handling.
 

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I don't know about the 159's but PU anti-roll bar bushes on a 156 don't affect the ride quality at all. Suspension arm bushes yes, but not the anti roll bar.
On the 156 the rubber bushes don't last more than 25,000 miles on the front arb, and they are a task to change, hence many go pu bushes on the arb. 159's probably very different I guess.

Also, I'm not sure that a stiffer arb will reduce dive and lift...I always thought that was the struts/coil springs. I believe (correct me if I'm wrong) that the arb gives lift/torsion to the outer wheel under sideways inertia/cornering?
 

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In general anti roll bars do exactly what the name suggests. It reduces body roll under cornering.

The same can be done by increasing spring rates however that has the side effect of increasing ride firmness in a straight line.

Diesel engines weigh more than petrols because they need to be stronger. This tends to include the block, crank and rods. Also as the 2.4 has an extra cylinder you're basically adding another 25 % of the weight as you have an extra piston, con rod, cylinder, section of crank, 4 extra valves etc.

I would think that the engine weight difference would be more than just 10kg. Would be interesting to find out the figures and see what the difference is.
 

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Diesel engines weigh more than petrols because they need to be stronger
Not sure that makes total sense - the bang of the TBI is about the same as the bang of the JTD so they surely both need to be the same strength. The 17:1 vs 8:1 ish compression ratios surely don't matter once the fuel is ignited - or am I into senior moments here?
 

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I would think that the engine weight difference would be more than just 10kg. Would be interesting to find out the figures and see what the difference is.
That would be really simple to do if somebody had a 2.0 + 2.4 JTD engine to weigh (pud237??), they're virtually identical apart from that extra middle pot on the 2.4.
 

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Can't find the engine weights online unfortunately. The compression ratio is slightly more than double so the con rods have to be able to withstand much higher loads than on the petrol versions.
 

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The later car weights are: Tbi 1385kg, 2.4 1585kg, 1.9 & 2.0 JTDM 1490kg. 3.2 1540kg

So a six cylinder petrol is still 45kg lighter than the 5 cylinder diesel. And the 2.0 diesel which is nearly identical to the Tbi is 105kg heavier. The diesels carry much more equipment to make the system work.
 
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