Suspension: 850: Switching back from coilovers - parts needed?

[dahamsta]

What parts would I need to switch from coilovers back to standard shocks and springs, i.e. what would have been taken off when the coilovers were fitted? I'm buying a kit from PFS which includes some parts but they're not sure if anything else will be needed, and I want to make sure I have everything when I hand it over to my mechanic.

Other options for the kit are Eibach springs, which I'll probably go for, and Koni Special Active (formerly FSD) shocks, however the FSDs put the kit close to a grand. Anyone gone with this setup on an 855R? Here's a copy and paste about the car that I sent to PFS:

- I have strut braces front and rear (in the boot, not underneath).
- An iPD anti-roll bar is installed in the rear, and I have one for installation in the front.
- The car is on 18s with 5mm spacers front and 20mm rear. I don't think (hope!) this should be a concern with a 30mm drop.
- The roadholding is great with the current setup, but the ride is pretty bad, mostly because of the aging coilovers.
- I'd like a good balance of ride and roadholding, with a slight bias to ride.

Switching because the car failed on a suspension imbalance, one of the shocks is forked. The rears have sagged a lot too. I was hoping to put this car on air at some point, but a) I can't afford it, and b) there's no-one available to fit it here.

[JohnM 855 T5R]

Originally Posted by dahamsta

Other options for the kit are Eibach springs, which I'll probably go for, and Koni Special Active (formerly FSD) shocks, however the FSDs put the kit close to a grand. Anyone gone with this setup on an 855R

In my opinion (and I'm sure others will disagree), save your money. Koni FSD shocks were tested by a number of magazines here and in the States on a range of cars and the general belief was that they didn't make any appreciable difference to either ride quality or handling. I personally know of 2 people who have had FSD's. One was standard factory fit on a Fiat 595 competizione. The owner found the ride to be terrible. The other was a replacement fit onto a BMW 4 series whose owner reckoned they were all hype as he found no difference in handling characteristics or ride. You would be better off going for Bilstein B4's which are more or less equivalent to standard or if you really are determined to have a stiffer ride, then Bilstein B6's (though I think you'll regret it as other owners on here have). As for springs, again, personally I would go for standard ride height. Lowering really makes very little appreciable difference in real terms on the road without a host of other suspension mods. In fact, lowering risks messing up the carefully worked out factory suspension geometry which was pretty damn good on the T-5R and 850/855R. Both had outstanding and class leading lateral G performance in their day.
As for parts, you'll want new damper top mounts anyway. I cant think of anything else.

Regards
John

[RollingThunder]

I'm with John on this

However, if you want to stray from OEM parts, then Eibach make good springs, as do H&R. For a budget option, consider Kilen springs - they are (or were) part of the Lesjofors group who made the original coil springs for Volvo back in the '90s. I fitted these and a set of Bilstein touring dampers to my last 940 estate and it was an excellent combination - along with the iPd anti roll bars.

[CNGBiFuel]

As with many mods, you're hard set to improve on something factory-developed if you don't intend to spend a lot more than is viable. Doing your own R&D is never going to be cheap.

It costs millions to develop a car, real developemt engineers have numerous permutations at their disposal, this to get where the car is at production. The aftermarket outfits don't do as much testing, simply because they can't.

The myth goes that a factory team of highly experienced development engineers can be outdone by a bloke with a box of spanners. This fallacy keeps the after-market goodies business going.

These were properly configured from the off... as fitted R variants and BiFuels, the best set-up is a set of new Nivomats with a 'nice new Nivomat price'. You'll get a proper ride and ride level. Compared with producing a lin-up of options to test for yourself, this is the cheapest way to get what you're after, knowing that this was done already... only that won't make it cheap.

Yes... you can bodge it with less, and it might work out, only the further you stray from what was done, the higher chance you'll get less.

As said 'Doing your own R&D is never going to be cheap.'

[JohnM 855 T5R]

Totally agree with all your views on this CNGBiFuel

Regards
John

[CNGBiFuel]

Love the car-trade. Seems many take it on board. I chuckle.

It gets risible… 150 mpg with special carburettors, some widget holds the secret of eternal-youth and huge civilisations live under the sea.

You know the kind of thing:

Stickers = +5 hp
Spoilers = +10hp
Big-bore fart cannon = + 50hp
Black paint = +100hp
These are race parts, so they’re certain to be "good for my car”.

Add a few upgrades together and any car’s a 700bhp fire-breathing monster doing 70mpg. Women drag you from your car and beg for sex. Lest we forget the beard-brigade that’ll only buy main dealer oil. plugs, filters etc, and don’t get me started on snake-oil, braided-hoses and the myriad big brake-fallacies?

The more you spend, the more you lose.

Don't have me wrong - Few could truly blame the car-trade. They want to sell 'race-parts' and.... er, we willingly suck up this tripe.

[JohnM 855 T5R]

Originally Posted by CNGBiFuel

and don’t get me started on snake-oil, braided-hoses and the myriad big brake-fallacies?

Once again, I agree with all your sentiments above wholeheartedly. I always chuckle at those people that upgrade to 302mm front brakes from 280mm and then say how much better they are and the improved feel. Utter b*****ks!! The pads are the same in both cases as are the calipers, thus the pad area is identical and it is the pad area that determines how much braking power you can get and the calipers determine the pedal feel. 302mm give no more braking power at all. Nor will they in anyway improve or change the feel of the brakes.
The police specified 302mm on their early T5's because with car chases, extreme high speeds on motorways and the like involving extreme very heavy braking and heat build up, the 302's give more heat dissipation and delay fade. Anyone driving even remotely sanely on the road wont reach the point at which fade becomes an issue. The 280's are more than up to the job.

I'm sure the 302's give bragging rights and a warm feel in the trouser department - but they don't brake any better. Wishful thinking and false expectation is a wonderful thing.

A fool and their money are easily parted (I got 125bhp extra for free by bolting a Heinz baked bean tin to the end of the exhaust. Keep the label on as without it you only get 100bhp)!

Regards
John

[CNGBiFuel]

2/10 see me.

Oh dear, oh dear.... not you as well? Friction is a factor of FORCE. Area, in this case 'pad/disc area' has no bearing on friction. Pads the size of a barn-door - about the same axis - will NOT increase friction.

https://www.youtube.com/watch?v=idYX7kkRqbs

302mm DO work because FORCE has an increase. How so? Moments of force, this by way of the distance from rotation increase, therefore FORCE increases. You were taught this in school at 12YO.See the see-saw.
Pad/disc area has a finite bearing on heat-dissipation, NOT friction. You were granted education, don't say we were never taught levers/ the see-saw because we all were... we were taught via the state. Was the cost of this wasted?

Now go away and shatter the standard boy-racer tripe and understand why in the case of a wider tyre, it is NOT the larger footprint that gives a friction increase. Here's a clue, it'll be to do with maintaining the contact-patch.

Ahem:

thus the pad area is identical and it is the pad area that determines how much braking power

Thus uttter, utter bollox...

Friction is a factor of FORCE, not area. Fit 302mm and we see a marked improvement from the force increase. The 'moments of force' get an increase by 22mm.

We'll get into heat-dispersal once we have AREA/FORCE out of the way.

At present, it's clear the vast majority don't understand the operation of brakes. There's many a big-brake myth, and large brakes do work, although in the round, NOT for the reasons those that fit them give us.

https://www.physlink.com/education/askexperts/ae200.cfm

[JohnM 855 T5R]

Another CNGBiFuel rant? I have to say, your knowledge of basic physics is somewhat rudimentary and the argument you put forward is very flawed as you are applying wholly inappropriate elements of the theory of mechanics. For my part, speaking as someone who a) has "A" level physics, b) was in production engineering at Ford for some years and c) rallied for 12 years engineering, building and maintaining my own rally cars I know enough about braking to dispel your notions.

Braking comes down to just three factors -
1) Pad area - obviously this determines how much friction material is in contact with the disc.
2) Friction material - the co-efficient of friction will, in simple terms, determine how well the pad "grips". A high co-efficient however as we all know comes at a price - the pads usually have a narrow optimum operating temperature range and work worse when too cold plus the pressure that needs to be applied to take advantage of high friction material is normally greater which leads to...
3) Clamping pressure (the force that is applied through the pads) - i.e., how hard you shove the pads onto the discs. Apart from the strength of your right foot, the amount of clamping pressure that can be applied is determined by the design of the caliper itself and its hydraulic relationship to the master cylinder (along with the brake booster which makes higher brake pressures possible without having to go to the gym.)

Having a larger 302mm disc and moving the caliper further out with the required mounting brackets put the pad into contact with a part of the disc which has a higher surface rotational speed. This makes absolutely no difference whatsoever in terms of the basic physics of braking. If you use the same pads, calipers, master cylinder and brake booster you will get diddy squat improvement on 302's. As I said, the only benefit is in extreme conditions where fade might be delayed due to the increased ability of a larger chunk of metal to soak up generated heat and the higher rotational speed at the rim of the vented disc to dissipate in the the airflow.

Back to the classroom and get your basic physics right

I like your rants when founded in common sense and fact - and I agree with you a good deal of the time. But sadly, a fact free rant just irritates.

Regards
John

[CNGBiFuel]

1) Pad area - obviously this determines how much friction material is in contact with the disc.

A: Of course, when all else is equal the larger the pad, the longer it takes to wear out. larger areas also shed heat quicker. You maintain a larger area gives a friction increase, only so far as it stays cool for longer. At the same temperature it doesn't. Else explain this:


https://www.youtube.com/watch?v=idYX7kkRqbs

2) Friction material - the co-efficient of friction will, in simple terms, determine how well the pad "grips". A high co-efficient however as we all know comes at a price - the pads usually have a narrow optimum operating temperature range and work worse when too cold plus the pressure that needs to be applied to take advantage of high friction material is normally greater which leads to...

A: I am in complete agreement.

3) Clamping pressure (the force that is applied through the pads) - i.e., how hard you shove the pads onto the discs. Apart from the strength of your right foot, the amount of clamping pressure that can be applied is determined by the design of the caliper itself and its hydraulic relationship to the master cylinder (along with the brake booster which makes higher brake pressures possible without having to go to the gym.)

A: Of course, let's call it 'force'.

Having a larger 302mm disc and moving the caliper further out with the required mounting brackets put the pad into contact with a part of the disc which has a higher surface rotational speed. This makes absolutely no difference whatsoever in terms of the basic physics of braking.

A: When you push an object across a table-top, first slowly, and then quicker are you doing the same 'work' in each case? If you wanted the 'table-top' to get hot would the speed you did thsi make a difference? I say, the greater rotational speed will increase heat, you don't, ergo...

If you use the same pads, calipers, master cylinder and brake booster you will get diddy squat improvement on 302's.

A: Not quite, you will see more friction, the Moments of force increase, The pad will now get hot quicker covering more ground than it did on a 280mm disc, we're doing more work.

As I said, the only benefit is in extreme conditions where fade might be delayed due to the increased ability of a larger chunk of metal to soak up generated heat and the higher rotational speed at the rim of the vented disc to dissipate in the the airflow.

A: Agreed a bigger chunk of metal (we can keep it at 280mm if we like?) will delay brake-fade, outside of race conditions, eg: an emergency stop, that alone is an improvement. It'll l take longer to cool - we'd hope to have stopped by then.

In my own experience fitting the 302mm kit does work, doing more work. If we go by your thinking, this can't be so?

However, if I'm correct and the 302mm is creating more friction, thsi via greater rotational speed and larger 'moments of force' - all else equal - there will be more heat. Of course this could all be more marketing-hype, yet witness that Mintex offer a harder pad for the 302mm disc. To cope with the higher rotational speed and the greater heat?

I think we'll have to agree to disagree. And for my part I lay prostrate at your feet, I shall remove my 302mm kit this minute. Christ it's cold out, I shall rub my hands together... slowly.