Lets talk Spring Load, Not the usual Spring Rate thread

[M-Sport fan]

maybe for recce it is possible I drive with almost the fiesta "active" stock suspension setup and know many people with bilstein b6 and stock springs that drive on rallycross tracks (a lot smoother than a rally stage), but if you go flat out without care, i think your chassis will get bent in some places

Yes, given that stage road recces here in the states must be driven at or below any posted, or otherwise speed limits, in as quiet and unobtrusive a manner as possible (I guess he used the 'quiet mode' in that FoRS's exhaust?).

It seems to be the same in Europe, given the videos I've seen of the Monte Carlo recce this year, given that even the street Yaris GRs driven by the Team Gazoo crews sounded quieter than the normal factory built cars.

 

[Rutschpartie]

So, just how much static ride height would I lose pairing the Spec Rs with B8s vs. B6es, and does the resultant higher 'load' mentioned above mean that the B8 setup will not allow the unibody to come as close to the (VERY rough) gravel stage roads as the same springs on the B6es during compression?

if you want i can measure the mounting holes/diameters of some spare fiesta active dampers/springs I have for the mk8 and send pictures. I can also send some old used ones from Austria if you pay for the shipment. Maybe it would be possible to retrofit them to an mk7 ST, they have same/larger tube+rod more travel and softer valving + internal bump stops. You could buy them directly from bilstein. For moderate/careful driving on offroad gravel roads they could be ideal. Fiesta ST Mk8 can use them without any modifications. Ofc you would need the active springs to for this to work. They are also very cheap compared to everything else. Also the suspension uses longer/bigger external bump stops than the ST that also helps to prevent killing your chassis.

Maybe it could also be enough to find out if it is easy to retrofit the mk8 ST supension to an mk7 ST, if yes the active suspension should also work.

 

[Rhys1983]

Have you seen any kind of pricing on those two AVO models at all?

I have given up on ALL of the U.S. based, or available in the USA coil over setups for this car, even including the ones which proclaim that they are built for (gravel and tarmac) rallying (I NEVER get a straight answer from any of them, and they give almost NO info about their product(s) at all ).

The R1’s are around $1600 and the R2’s are about $3300. I did manage to speak to someone today and he was saying that they’re built to order and that you can choose your spring rates in 25lb/in increments.
The suspension will have more travel than standard as they’re a rally shock.
The springs are linear as well which is good. The difference from the standard set up is that these are coilovers front and back as opposed to having a separate damper and spring set up on the back. I’ve spoken to someone who sells suspension and he said that this won’t matter and they’ll still work fine. I’m not sure if a full coilover set up in the back will be better or worse than the original set up? Perhaps someone more knowledgeable than me can shed some light on this!

 

[Rhys1983]

hey, few things I want to add:

Roll centre adjustment is RLY complicated. It will influence a lot of things, including dynamic change of toe, camber and your % of ackermann steering. Understanding what it rly is and measuring it can take time. Simply putting stiffer springs or spacers to your front suspension will not rly work wonders, it can even make some things worse. The roll center advice and adjusters you can buy on some "tuning" websites are 75% garbage. This is a good blog read if you are not scared of formulas: Rodrigo Santos - a discussion on steady state lateral weight transfer and how to use it in setup

If you rly want to do this yourself, you need to do the following steps, some of them are complicated and youll need to do research and testing:

1.) Measure your suspension and calculate roll centre for rear AND front suspension.
2.) Measure and calculate CG of your car
3.) Calculate or simulate static load transfer of your car
4.) test and measure your car on the track (this can be complex and Sensors can be expensive to borrow)
5.) do adjustments, go back to step 3

this can be a time consuming and expensive process, also you need to get the tools and learn the math/physics behind it. Load transfer is NOT easily understood by roll centre height. Body roll is NOT easily related to load transfer. Handling is a lot more than those two topics. Increasig roll inertia or roll stiffness on one end of the car changes load transfer to/on the other side, so you rly need to have a good understanding what you are changing.

My advice: try stiffer (not shorter) springs front and rear with your b8, see if the reduced body roll feels better. If yes, have a good time driving it on the streets ✌️

Reigers are expensive and for rally, they are durable and have great valving and damping, but for everyday street use in a non seam welded car with no cage it is maybe not the right thing. If you want to get into some rough road/gravel driving you also need to adapt and reinforce your suspension pick up points with at least a cage. If not you will fuck up stuff in the long run.

Suspension and geometry setting really are a dark art!
To be honest the car doesn’t roll about at all now. It corners really flat, the turning is pin sharp and I have great feedback from the road. I was just wandering if there are further important to be made. I am thinking of taking it to a suspension set up specialist and he can have a look at it and see if he thinks if it has enough travel and to fit my DNA caster/camber control arms and see what the roll centre is like i.e. see if the control arms are too parallel and see if a spacer would help.
Like I was saying, if there would be a big improvement in fitting rally suspension which will have more travel, adjustments and ride height setting I’m tempted to go with the AVO rally kit. The only thing is, these are coilovers front and back as opposed to the rear separate strut and shock of the B8’s. Do you know if this set up will work on the back, or are there any negatives?

 

[FiestaSTdude]

If you want to get into some rough road/gravel driving you also need to adapt and reinforce your suspension pick up points with at least a cage. If not you will fuck up stuff in the long run.

Would this apply only if you are doing actual rally stuff at like 80 mph, or could I be damaging my car going like 30-40ish?
I don’t have money for a cage but it would look really nice lol

 

[M-Sport fan]

The difference from the standard set up is that these are coilovers front and back as opposed to having a separate damper and spring set up on the back. I’ve spoken to someone who sells suspension and he said that this won’t matter and they’ll still work fine. I’m not sure if a full coilover set up in the back will be better or worse than the original set up? Perhaps someone more knowledgeable than me can shed some light on this!

Many on here have already stated long ago that a setup like that would require MUCH rear shock tower reinforcement, a VERY thick welded-in plate on the top AND bottom of the mounting plate/surface at a minimum, and maybe even some welded-in bracing (like a tied-in cage does).

Given that they were built for stage rallying that may not be a problem for that use since all of that strengthening/reinforcement (and then some!) is getting done anyway.

But for mostly street use, divorcing the spring from the damper in the back would have been a better move, as even the Reiger R2 setup for our rides does just that.

 

[Rutschpartie]

Would this apply only if you are doing actual rally stuff at like 80 mph, or could I be damaging my car going like 30-40ish?
I don’t have money for a cage but it would look really nice lol

It depends on the roughness of the road/stage, there is no exact speed limit or threshold I can give you, but believe me, you will feel it.. If you go with 40mph over rly rough gravel on a stock setup without reinforced parts your dampers will run out of travel and your chassis will need to absorb the impacts -> this you will feel 100% and it can damage your chassis. On smooth prepared gravel without medium/large holes, should be even ok with the stock suspension

 

[Rutschpartie]

Suspension and geometry setting really are a dark art!
To be honest the car doesn’t roll about at all now. It corners really flat, the turning is pin sharp and I have great feedback from the road. I was just wandering if there are further important to be made. I am thinking of taking it to a suspension set up specialist and he can have a look at it and see if he thinks if it has enough travel and to fit my DNA caster/camber control arms and see what the roll centre is like i.e. see if the control arms are too parallel and see if a spacer would help.
Like I was saying, if there would be a big improvement in fitting rally suspension which will have more travel, adjustments and ride height setting I’m tempted to go with the AVO rally kit. The only thing is, these are coilovers front and back as opposed to the rear separate strut and shock of the B8’s. Do you know if this set up will work on the back, or are there any negatives?

not rly a dark art, just a lot of engineering/physics involved. If you want to learn about it there are some good books used in racing engineering classes, but for them to rly make sense you need to read a little physics/mechanics first maybe. There is a lot of misinformation on the internet by people who have no idea about this, unfortunately also on 90% of the well known sites/shops run by mechanics who have 0 engineering/physics background. The classic read (but a long one): milliken - race car vehicle dynamics

If you already understand some of this stuff you could think about what "improvement" you rly want. Do you want more grip, do you want it front or rear (understeer/oversteer), do you want the steering to feel more direct or "smoother" handling without unsettling the car, do you want smooth race track lap time improvements or suspension travel increase for rough roads? Or do you maybe just want somebody doing your setup and trusting him while he tells you it will be "better" or "optimal" for your peace of mind. If yes, find a good suspension engineer you can afford.

Just changing parts by listening to somebody in any forum without fully understanding it will VERY likely not improve things (unfortunately), not because people here are stupid or want to harm your setup, but because it is more complicated than they think...

 

[Rhys1983]

Many on here have already stated long ago that a setup like that would require MUCH rear shock tower reinforcement, a VERY thick welded-in plate on the top AND bottom of the mounting plate/surface at a minimum, and maybe even some welded-in bracing (like a tied-in cage does).

Given that they were built for stage rallying that may not be a problem for that use since all of that strengthening/reinforcement (and then some!) is getting done anyway.

But for mostly street use, divorcing the spring from the damper in the back would have been a better move, as even the Reiger R2 setup for our rides does just that.

Ah right, so it looks like I’d need to stick to the divorced rear spring/damper set up at the rear.
So from the sounds of things, it looks like sticking to the set up I have now is the best option unless I can get hold of some second hand reigers! The search continues!

 

[Rhys1983]

not rly a dark art, just a lot of engineering/physics involved. If you want to learn about it there are some good books used in racing engineering classes, but for them to rly make sense you need to read a little physics/mechanics first maybe. There is a lot of misinformation on the internet by people who have no idea about this, unfortunately also on 90% of the well known sites/shops run by mechanics who have 0 engineering/physics background. The classic read (but a long one): milliken - race car vehicle dynamics

If you already understand some of this stuff you could think about what "improvement" you rly want. Do you want more grip, do you want it front or rear (understeer/oversteer), do you want the steering to feel more direct or "smoother" handling without unsettling the car, do you want smooth race track lap time improvements or suspension travel increase for rough roads? Or do you maybe just want somebody doing your setup and trusting him while he tells you it will be "better" or "optimal" for your peace of mind. If yes, find a good suspension engineer you can afford.

Just changing parts by listening to somebody in any forum without fully understanding it will VERY likely not improve things (unfortunately), not because people here are stupid or want to harm your setup, but because it is more complicated than they think...

Yes, it’s easy to get drawn into listening to various forums and reading what other people suggest!
I guess what I’m looking for at the moment is for better control on uneven surfaces and bumps. The car can get unsettled a bit in these situations during fast road use.
I think the way forward for me would be to take the car into a suspension specialist for now to get the alignment done and check everything.
I will still be keen an eye out for some second hand re-conditioned tarmac reigers if they come up. As it will be only used for fast road, I wouldn’t have thought that the chassis/seams would need any strengthening as it won’t be used as a rally car.

 

[Rutschpartie]

Yes, it’s easy to get drawn into listening to various forums and reading what other people suggest!
I guess what I’m looking for at the moment is for better control on uneven surfaces and bumps. The car can get unsettled a bit in these situations during fast road use.
I think the way forward for me would be to take the car into a suspension specialist for now to get the alignment done and check everything.
I will still be keen an eye out for some second hand re-conditioned tarmac reigers if they come up. As it will be only used for fast road, I wouldn’t have thought that the chassis/seams would need any strengthening as it won’t be used as a rally car.

If you want to go over regular roads with potholes it should be enough to get rid of bump steer without changing ackermann % too much by simply adjusting your tie rod pick up points or steering rack height (also here you have to calculate/measure the actual toe curve! Not just slap in some random spacer or balljoint from hardrace), a specialist can do that and it will not be expensive. Also going for stiffer springs is not the best idea for pothole/uneven roads. Honestly, for this kind of roads I think the stock fiesta ST springs with b6/8 dampers is what you want, should give you enough travel and is not too stiff. Also the geometry will be almost as intended by the ford suspension engineers who designed the car, they did a much much better job than some random forum guy advice. You can still play around with setting static toe/camber for your wheels and make some small adjustments with the dna hardware mounted.

 

[Rhys1983]

If you want to go over regular roads with potholes it should be enough to get rid of bump steer without changing ackermann % too much by simply adjusting your tie rod pick up points or steering rack height (also here you have to calculate/measure the actual toe curve! Not just slap in some random spacer or balljoint from hardrace), a specialist can do that and it will not be expensive. Also going for stiffer springs is not the best idea for pothole/uneven roads. Honestly, for this kind of roads I think the stock fiesta ST springs with b6/8 dampers is what you want, should give you enough travel and is not too stiff. Also the geometry will be almost as intended by the ford suspension engineers who designed the car, they did a much much better job than some random forum guy advice. You can still play around with setting static toe/camber for your wheels and make some small adjustments with the dna hardware mounted.

Thanks for the info @Rutschpartie. That’s good to know. Yes the roads around here are very uneven with lots of bumpy/broken tarmac so I’m looking for a set up that will work well. So in regards to standard ST springs, would you go for the pre ‘16 stiffer set up, or the newer softer springs? The Eibach springs that I have now are slightly stiffer than the pre ‘16 springs and about 20mm lower.

 

[Rutschpartie]

Thanks for the info @Rutschpartie. That’s good to know. Yes the roads around here are very uneven with lots of bumpy/broken tarmac so I’m looking for a set up that will work well. So in regards to standard ST springs, would you go for the pre ‘16 stiffer set up, or the newer softer springs? The Eibach springs that I have now are slightly stiffer than the pre ‘16 springs and about 20mm lower.

If you like your current spring rate, take the one closer to it and try to get rid of too much bump steer without changing your ackermann % (toe angle difference in steering), small potholes will be ok, large/deep ones will stay a pain. If after that you still have the feeling driving over bumps/holes unsettles the car/steering too much you need to soften the setup. But this will include thinking about dampers, sway bars and rear axle.

 

[Rhys1983]

If you like your current spring rate, take the one closer to it and try to get rid of too much bump steer without changing your ackermann % (toe angle difference in steering), small potholes will be ok, large/deep ones will stay a pain. If after that you still have the feeling driving over bumps/holes unsettles the car/steering too much you need to soften the setup. But this will include thinking about dampers, sway bars and rear axle.

As the Eibach springs are of a similar rate to the old st springs, would fitting a 15mm spacer have the same effect as fitting a pre ‘16 spring?
I think that it should be quite east to get hold of newer ‘16+ springs online so that would give an option to soften the ride.
Would fitting standard springs into B8’s create a higher spring load and a stiffer ride as a result?
The rear Eibach springs are progressive and the standard ones are linear, but I’ve had a look at my rear springs and it looks like the progressive part of the springs are binding, which would possibly make the spring behave like a linear spring?

 

[Rutschpartie]

As the Eibach springs are of a similar rate to the old st springs, would fitting a 15mm spacer have the same effect as fitting a pre ‘16 spring?
I think that it should be quite east to get hold of newer ‘16+ springs online so that would give an option to soften the ride.
Would fitting standard springs into B8’s create a higher spring load and a stiffer ride as a result?
The rear Eibach springs are progressive and the standard ones are linear, but I’ve had a look at my rear springs and it looks like the progressive part of the springs are binding, which would possibly make the spring behave like a linear spring?

Fitting a spacer could be ok, but only if it is not possible to fully compress the spring when hitting/compressing the bump stop, if this is the case it will take the impact <- not good! so it is not exactly the same but could be an option if you do not kill the spring itself under full compression (enough air left between the coils). For the spring load: it will make a difference, but you would rly have to measure/test how much, i think it would be minimal. Depends on the b8.

 

[Rhys1983]

Fitting a spacer could be ok, but only if it is not possible to fully compress the spring when hitting/compressing the bump stop, if this is the case it will take the impact <- not good! so it is not exactly the same but could be an option if you do not kill the spring itself under full compression (enough air left between the coils). For the spring load: it will make a difference, but you would rly have to measure/test how much, i think it would be minimal. Depends on the b8.

Thanks for the advice. I’ll get the suspension set up garage to have a look to see what they think and take some measurements to see if the gaps between the coils are big enough.

 

[M-Sport fan]

Yes, it’s easy to get drawn into listening to various forums and reading what other people suggest!
I guess what I’m looking for at the moment is for better control on uneven surfaces and bumps. The car can get unsettled a bit in these situations during fast road use.
I think the way forward for me would be to take the car into a suspension specialist for now to get the alignment done and check everything.
I will still be keen an eye out for some second hand re-conditioned tarmac reigers if they come up. As it will be only used for fast road, I wouldn’t have thought that the chassis/seams would need any strengthening as it won’t be used as a rally car.

My guess (with all due apologies/concessions to Rutschpartie above) would be that those tarmac R2 Reigers would be just fine, even without all of the actual rally car chassis/unibody seam welding and reinforcement, as long as you stuck with their roughest tarmac road spec valving, and spring rates.

You most likely will have to change out the front uprights/knuckles for the base Fiesta versions though, but I think that you already know this, correct?

 

[Rhys1983]

My guess (with all due apologies/concessions to Rutschpartie above) would be that those tarmac R2 Reigers would be just fine, even without all of the actual rally car chassis/unibody seam welding and reinforcement, as long as you stuck with their roughest tarmac road spec valving, and spring rates.

You most likely will have to change out the front uprights/knuckles for the base Fiesta versions though, but I think that you already know this, correct?

Yes, I’d be looking at quite a soft set up for broken tarmac similar to the roads you see in Irish road rallies.
You mentioned before that the steering upright/knuckle would need changing. Would this be an easy job to do? Would I need to change anything else on the car as well?

 

[Rutschpartie]

My guess (with all due apologies/concessions to Rutschpartie above) would be that those tarmac R2 Reigers would be just fine, even without all of the actual rally car chassis/unibody seam welding and reinforcement, as long as you stuck with their roughest tarmac road spec valving, and spring rates.

You most likely will have to change out the front uprights/knuckles for the base Fiesta versions though, but I think that you already know this, correct?

No need to apologize, i think tarmac reigers will be fantastic!! (but financial overkill for your use) if you have the money and want them, go for it, but be aware that you do not need them for your daily spirited driving, also i think you do not need a cage for that

 

[Fusion Works]

Yes, it’s easy to get drawn into listening to various forums and reading what other people suggest!
I guess what I’m looking for at the moment is for better control on uneven surfaces and bumps. The car can get unsettled a bit in these situations during fast road use.
I think the way forward for me would be to take the car into a suspension specialist for now to get the alignment done and check everything.
I will still be keen an eye out for some second hand re-conditioned tarmac reigers if they come up. As it will be only used for fast road, I wouldn’t have thought that the chassis/seams would need any strengthening as it won’t be used as a rally car.

This is where a custom valving comes into play. The "unsettled" feeling you get is a lack of rebound control. I was looking at the dyno curves last night and the OE ST rear damper has higher forces than the Bilstein B8 does. I am starting to think mixing and matching may be the answer for an off the shelf basic setup. If I can round up another ST rear damper I may swap it on to my car to see how it feels. I am rounding up some bleed shims to change the valving in my custom dampers to see if I can make it a better match for a street setup.

You most likely will have to change out the front uprights/knuckles for the base Fiesta versions though, but I think that you already know this, correct?

If you change to a base Fiesta knuckle your steering rate changes. That was one of the changes on the ST, they shortened the steering arm to make the steering quicker. I would hate to give up the quick steering on this car.