General Anyone recognize this car?

vexorg

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Besides I like my handling / brakes to be pin-sharp, makes the car far more enjoyable to me than having an extra 50 bhp or whatever, given the roads round here.
Ok, but if the type of rear disc is the deciding factor if you make it round a corner or not then maybe you need to adjust your driving style.

I have no issue with you killing yourself, if when people take out other innocent people then it's more of a problem.
 
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mj2k
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Ok, but if the type of rear disc is the deciding factor if you make it round a corner or not then maybe you need to adjust your driving style.

I have no issue with you killing yourself, if when people take out other innocent people then it's more of a problem.

I'm perfectly capable thanks, I've been driving Subarus with 300+bhp, a low centre of gravity and 4wd for quite a number of years, and before that an AMG E50, Alfa 156 GTA, Xsara VTS, Pug 205 / 306 gti(6), Alfa GTV v6 and Lancia Delta HF... Oh, and Capris. Four of them in a row. Oops, forgot the police tuned Senator 3.0 24v and the BMW 2002. And my very first car (there were a few self-restored classics / normal hatchbacks in between) - a Renault 6 which my friends and I put a 5 Gordini engine in; that one taught me the value of upgrading suspension / brakes if you add more horses, the hard way. And your experience of performance cars is...?

Brake balance is a science rather than an art though, and I'm not 100% sure if Fiat got it right on the Abarth judging by the number of reviews saying it becomes too nose-heavy on heavy braking so if a simple upgrade of rear brake pads sorts it, it's a win-win for everyone who enjoys driving an Abarth. And I like experimenting with things :)
 
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mj2k
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Wahey, new toys to go with my Brembos :)

iQ03TX.jpg


Still need to wait for that MOT before I start playing though, it's with the testers today...

BTW if anyone's interested, according to the 'brakemath' spreadsheet, adding the Brembos shifts the brake balance 8% towards the front; not a biggie, but if it's already heavily weighted towards the front that's not a good thing; once again according to 'brakemath' it's 50% more biased towards the front than a typical Subaru. Admittedly since that's 60/40 rwd car and has more weight at the back the rear brakes are more important, but that's still a pretty heavy front bias on the Abarth.

Fitting 'performance' (not race) pads to the rear would change the bias 13% towards the rear rather than 8% towards the front with the Brembos, maybe that's too much given the roughly 70/30 weight distribution on the Abarth and it may result in rear lockup instead, but it's got to be worth a try if it's too nose-heavy with the Brembos :idea:
 
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jrkitching

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Actually, talking of handling / brakes, I've noticed the car gives an almost imperceptible wiggle if you back off the power a lot on a straight, as you're approaching a corner.

Most likely you're just discovering the limits of a twist beam suspension setup.

BTW if anyone's interested, according to the 'brakemath' spreadsheet, adding the Brembos shifts the brake balance 8% towards the front; not a biggie, but if it's already heavily weighted towards the front that's not a good thing; once again according to 'brakemath' it's 50% more biased towards the front than a typical Subaru. Admittedly since that's 60/40 rwd car and has more weight at the back the rear brakes are more important, but that's still a pretty heavy front bias on the Abarth.

I'd have thought the limiting factor will be the (lack of) weight over the rear wheels, so I'd expect the benefits of any upgrade to the brakes at the back end to be at best marginal, at least when there's only one or two people in the car.

Some small family hatchbacks (and some light vans) struggle to pass an MOT brake test without a bag of sand in the boot, as when unloaded, the rear wheels lock before reaching the minimum braking effort threshold. Even on a 1.2 driven pensioner-style, the difference in both handing and braking when 4-up is quite noticeable.

Oh, and Capris. Four of them in a row.

Anyone who's driven hard in the higher performance variants will likely have decent driving skills.
 
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mj2k
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I'd have thought the limiting factor will be the (lack of) weight over the rear wheels, so I'd expect the benefits of any upgrade to the brakes at the back end to be at best marginal, at least when there's only one or two people in the car.

Some small family hatchbacks (and some light vans) struggle to pass an MOT brake test without a bag of sand in the boot, as when unloaded, the rear wheels lock before reaching the minimum braking effort threshold. Even on a 1.2 driven pensioner-style, the difference in both handing and braking when 4-up is quite noticeable.

Yes, that's what I was thinking, despite the 'over-bias' to the front, maybe shifting the bias around 10% towards the rear would be too much. And too much rear brake bias would lead to the rear brakes locking first in wet braking since even more weight would be shifted forwards during heavy braking, and the last thing you want is a fishtailing car in a wet emergency stop :eek:

That's one big advantage to keeping a full fuel tank and keeping the rear seats - it puts a bit more weight over the rear axle, making that rear end lockup less likely.
 
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mj2k
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Most likely you're just discovering the limits of a twist beam suspension setup.

Ahh, sounds plausible (y)

Prob something I'll get used to then, and maybe the wiggle is also the reason for that weird little dead spot in the power assistance when in sport mode and the wheels are facing straight ahead - that'd hide it.
 
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mj2k
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Does this beast not have ABS?

Mmm, I guess, but if the rears lock instantly and the ABS takes a few milliseconds to release them that's still the start of a slide, and if they instantly lock again as soon as the ABS reengages them (and so on) the best ABS in the world won't save you from a fishy fate. Not quite done that, but I did get a very weird 'loose backside' feeling under a heavy braking test when I was messing around with different rear brake configurations in the past and totally mucked up the brake bias (those calipers came straight off and went back on Ebay, and I stopped eating 3 week old currys ;) )

Car passed it's MOT with flying colours btw :slayer:

Edit: Blimey, it's done 600 miles since it's last MOT, and 70 of those are by me, guess it must have been off the road for a bit longer than 2 months post-crash :eek:
 
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mj2k
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Ooh, missed the Capri comment, ta for that (y)

The brakes were a whole new level of dreadful, but I def wouldn't have put the Capri as the worst handling car I've ever driven despite it's horse-and-cart derived rear suspension. It was pretty predictable and the light, precise, feedback-filled steering made it easy to catch when the tail started to flip out. So that comes in at #5 for me :)

#4 worst was the Alfa GTA (unmodified) - the factory suspension setup was terrible and the engine was really too heavy and torquey for a 1980s Tipo-based chassis. So it crashed, wallowed and seemingly bump-steered you onto the wrong side of the road if you hit a twig wrong mid-corner.

#3 worst was the VW type 3 fastback - basically a Beetle with a 1.6 fuel injected engine; that was never going to be a recipe for predictable cornering.

#2 Worst were the Triumph Herald (and the Herald-based Bond Equipe) - the rear wheels developed positive camber under load, which made cornering, er, interesting unless you fitted them with crossply tyres rather than the grippier radials to ensure the rear end kicked out in a predictable manner.

Which leaves the No1 worst handling car I've ever had the misfortune to own - the Skoda 130 Rapid. This combined rear engine, rwd with an even more ancient suspension design (front and rear) than the Capri and a hulking great cast iron engine block to ensure they drove like a wonky pendulum if they actually started. This horrible thing would tailspin on a moist roundabout at 15mph :yuck:
 
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vexorg

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Most likely you're just discovering the limits of a twist beam suspension setup.
Most likely it's something worn or bent in the suspension. (lets say worn as you dont like the idea of bent)


It's a fairly basic suspension setup, not too many bushes to change
 
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mj2k
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Most likely it's something worn or bent in the suspension. (lets say worn as you dont like the idea of bent)


It's a fairly basic suspension setup, not too many bushes to change

Not much left which could be bent tbh, it's all been replaced. And it sailed through the MOT without any advisories, it's only done 33k and the tracking was fine, so there can't be any serious wear. I haven't checked out the rear end bushes but I can hear a v slight bearing rumble from the front end and the o/s/f wheel bearing does have a tiny bit of play (the hub carrier was 2nd hand), so will try replacing that sometime to see if it makes any difference.

Though chances are it is just me being over-sensitive and expecting too much of the little thing; that wiggle might even become endearing once I'm used to it, like it's a bit over-excited. The Alfa 156 GTA had a similar quirk - it felt 'alive' when driven hard (modified suspension and a Quaife/Q4 diff needed to drive it anywhere near it's potential), which gained it a lot of fans; this was caused by the bodyshell twisting under heavy acceleration however, which generally is not thought of as a good thing.
 
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mj2k
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Ooh, it's back with a snazzy new interface :D

Took it on my usual 14 mile round trip down country roads to the local Tesco, definitely about 10mph slower out of the corners than my old modified Subaru Legacy wagon. But then I'm not 100% confident in it yet and I suspect the centre of gravity will be somewhat higher and nearer the front, so not too surprising.

Still great fun though, and as a major plus on the way back all the shopping crammed into the boot, which meant the bags stayed upright and I didn't have to spend another 10 minutes hunting for lost groceries rolling around in the back, like I did with the Legacy
;D


BTW I think I got to the bottom of my 'wiggle' by using a bit of 'o level' / gcse physics - it's the the 'wobble blob' strut top mounts. Since they're basically just a big lump of rubber and aren't anchored to the car, they're pretty much free to move as they want, within the range of movement defined by the lower arms. I've noticed if I'm approaching a corner at wide open throttle (the clockwise torque will no doubt be pulling the strut tops anticlockwise) and back off the power a lot, the car gives that barely perceptible wiggle; doesn't seem to be anything wrong with the car at all, so my thinking is once you remove the torque from the engine going at full pelt the strut tops spring back to their default location, which would cause that little wiggle. Quite endearing, like an over-excited puppy, but if my thinking is correct, the castor of the front wheels actually changes under hard acceleration
:blink:


I suspect those coilovers / modified strut tops will be moving up my wish list a little 🤔
 
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vexorg

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Not convinced on the top strut, I've driven quite a few cars with similar set up, and more power, none have ever given a wiggle. Maybe they are just worn.

On the rear brake problem, wont better brakes on the back make it worse and more likely to lock up?
 
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mj2k
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Not convinced on the top strut, I've driven quite a few cars with similar set up, and more power, none have ever given a wiggle. Maybe they are just worn.

On the rear brake problem, wont better brakes on the back make it worse and more likely to lock up?

I doubt it, most cars have the strut top mount attached to the inner wing with studs and bolts, not interference fit with a cup on the top (that's the rusty cup thingy on the top of the struts) to prevent it popping out, and an elongated strut top cutout. I believe this is the 'revolutionary strut design' mentioned in the 500 blurb; I can see the advantages tbh - for acceleration it'll slightly increase the castor which will lead to better straight line stability, but at low speed the castor will return to normal for better manoeuverability. Also having no direct connection to the bodywork will definitely help with comfort and NVH on such a tiny car, but the payoff (apart from that minute wiggle which I spotted) is that the steering won't feel so 'connected' with the road, something which is often mentioned in 500 / Abarth road tests.

Also as a quick test, try jacking up both front wheels, with the handbrake on. Then lower the car to the ground, let off the handbrake and see how much it moves backwards as the front suspension settles; it's a surprisingly large amount for such a small car...
 
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vexorg

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I was meaning between the strut top mounting rubber and the body. Yeah, the strut top is bolted, but the whole strut just sit in place due to the weight of the car on the rubber mount.

On many cars (with macpherson struts), you can see the top of the shock move a bit as you turn the steering
 
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mj2k
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I was meaning between the strut top mounting rubber and the body. Yeah, the strut top is bolted, but the whole strut just sit in place due to the weight of the car on the rubber mount.

On many cars (with macpherson struts), you can see the top of the shock move a bit as you turn the steering

Indeed, that's pretty normal, there's usually a bit of tolerance built in because the bearings are mounted in rubber. These wear out in due course, clunk and get an MOT fail just like the 500 ones (though with most old Fords the inner wing rots through long before the strut mount fails), but the amount of movement is fairly limited and the mount itself is firmly bolted in place, e.g (I'm just using Ford here):

arrow-jpg.117646


But starting with the Mk1 Ka (the USDM 500 is the same as this) the strut mount is an interference fit with a cup to stop it popping out; presumably this is a nice, cheap way to reduce NVH. Not as precise as the older design and more prone to wearing out, but once again the movement is fairly limited:
image-1271628377-jpg.131524


The main difference is on the EU market 500 / Panda / Ka Mk2 they've elongated the mount to allow more fore / aft movement:

images


And enlarged the mount rubber too (presumably the arrow, which is rubber coated metal, prevents the assembly moving backwards):
609580180.jpg

USDM 500 strut mount for comparison:
FIAT500strutTOPmount1-750x563-4.jpg


As for the brake comment, yes, if you get the brake balance wrong it'll make it more likely to lockup at the back and fishtail; setting it up is more of a science than an art though once you know the brake stopping power and weight distribution you can make a pretty good guess as to what will work well and what won't; if you're comparing similar brake setups, a lot of the complexities remain static so can be removed from the equation (much like 500x+750 = 50y+750 therefore 10x=y) which takes it down to a direct ratio of front->rear brake torque to calculate the balance.
 
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Olliver

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...

As for the brake comment, yes, if you get the brake balance wrong it'll make it more likely to lockup at the back and fishtail; setting it up is more of a science than an art though once you know the brake stopping power and weight distribution you can make a pretty good guess as to what will work well and what won't; if you're comparing similar brake setups, a lot of the complexities remain static so can be removed from the equation (much like 500x+750 = 50y+750 therefore 10x=y) which takes it down to a direct ratio of front->rear brake torque to calculate the balance.

I think the only way to improve is to bring weight in the trunk, e.g. the battery...
I was always wondering that the Brembo brake-kit conversion that is also officially offered by Abarth does not include any recalibration to the ABS / ESP control unit. I think this due to the fact the that the displaced volume stays the same. The standard floating caliper has a 54mm piston, the Brembos have four 38mm pistons. So this means the total piston area of the Brembo caliper is 4537mm², the area of the floating caliper is 2.290mm², but it has to travel the double way due to the floating construction. So in the end the displaced volume stays nearly the same and is even little smaller with the Brembos...
But anyhow, if the brake force at the front is too high, the 595 will lift it´s ass, and than it doesn´t matter any more how much or few you brake at the rear...;)
 

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mj2k
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I think the only way to improve is to bring weight in the trunk, e.g. the battery...
I was always wondering that the Brembo brake-kit conversion that is also officially offered by Abarth does not include any recalibration to the ABS / ESP control unit. I think this due to the fact the that the displaced volume stays the same. The standard floating caliper has a 54mm piston, the Brembos have four 38mm pistons. So this means the total piston area of the Brembo caliper is 4537mm², the area of the floating caliper is 2.290mm², but it has to travel the double way due to the floating construction. So in the end the displaced volume stays nearly the same and is even little smaller with the Brembos...
But anyhow, if the brake force at the front is too high, the 595 will lift it´s ass, and than it doesn´t matter any more how much or few you brake at the rear...;)

Yes I noticed that with the Brembo kit too, the main increase comes from the increase in rotor diameter, plus Brembos give a nice feel to the brakes judging by my previous experiences with them (mostly down to how much fluid has to be moved by the pedal for a floating caliper vs a fixed one). But according to my calculations it moves the bias around 8% towards the front, which might be too far under heavy braking:

1637921699036.jpeg
I've been thinking a bit around this and it'd be nice to make the rear brakes 10% better to match the front, but that's tricky given the car's weight distribution. Possibly the best way, for a road car at least, is to leave the rear seats in, keep the fuel tank quite full and put an actual wheel in the spare wheel well (or maybe 2 smaller batteries?) since those all sit over the rear axle (with no overhang), and put a modestly harder set of pads on the back.

Possibly the cabrio's roof mech being in the back might help too, but that has negative payoffs around roll centre and possibly structural rigidity (a lot of cabrio owners complain the mirrors vibrate, which might be a sign of scuttle shake despite the rigid sides).
 
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Olliver

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Possibly the best way, for a road car at least, is to leave the rear seats in, keep the fuel tank quite full and put an actual wheel in the spare wheel well (or maybe 2 smaller batteries?) since those all sit over the rear axle (with no overhang), and put a modestly harder set of pads on the back.

Possibly the cabrio's roof mech being in the back might help too, but that has negative payoffs around roll centre and possibly structural rigidity (a lot of cabrio owners complain the mirrors vibrate, which might be a sign of scuttle shake despite the rigid sides).

In my Clio, I installed two 12V 20Ah batteries in the left and right sides of the back seats. This is sufficient from capacity point of view as I drive the car only in summer. But you have transferred some weight to the rear und you don´t loose space. The only thing you have take care for is, same cable length until to the point where you connect the two plus cables of the batteries.

I never experienced vibrating mirros in our current and also previous Cabrio.

Anyhow it´s always nice to see them lifting their backs...😆
 

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mj2k
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In my Clio, I installed two 12V 20Ah batteries in the left and right sides of the back seats. This is sufficient from capacity point of view as I drive the car only in summer. But you have transferred some weight to the rear und you don´t loose space. The only thing you have take care for is, same cable length until to the point where you connect the two plus cables of the batteries.

I never experienced vibrating mirros in our current and also previous Cabrio.

Anyhow it´s always nice to see them lifting their backs...😆

FCA seem to like making cars which can do a handstand 😁

JeepRenegade-Stoppie.jpg


I was planning to go for the cabrio myself originally (planned to get a standard 500c and a crash damaged Essesse donor, and make my own) and even went as far as arranging to buy a 1.2 500c which looked like a bumble bee but ended up getting my current one instead, mainly because of a Copart bidding anomaly. I do rather like the black paint and heritage brown interior on mine though (reminds me of my old Alfa GTV), so I'm sticking with that, even though the giant glass sunroof probably puts the roll centre somewhere level with my eyebrows ;)

Might have to play with the battery location, sounds like a sensible plan, but going to try it with the Brembos, EBC Greenstuff (v slight upgrade) pads at the back and standard Brembo pads at the front to see how it feels and performs for a start.
 
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