Bilstein B4s too hard :-(
Discussion
I have a Peugeot 607 HDI automatic, which I mostly use around town and on the motorway.
The suspension has always been a little firm on it for a French car with very flat cornering, but last year it started to bounce a bit on certain roads and it scored an MOT advisory for leaking front shocks, so I did a little research and someone was saying that the Bilstein B4 is a comfortable shock, and to be honest it was the only "quality" name that I recognised and not much more expensive than the cheapest. So I bought and fitted them.
After a year the suspension is starting to annoy me.
On speed bumps it's okay, and on smooth motorways it's okay.
Around town it's terrible with small bumps shaking the whole car. On block paving I can feel every block and if the council has put a high grip surface I can feel it.
I have 225/55R16 winter tyres on it the moment with 32psi in them, and in the summer 225/50/R17. That doesn't seem to make any difference.
I also did a little research on the car. First I put it on a DVLA weighbridge and got 960kg on the front and 800kg on the back (the boot wasn't empty and a full tank).
Next I got another used spring with the same colour codes on it and measured the spring rate. Basically I used the weight of the car minus the weight of wheel, tyre, strut, hub and brakes, so 440kg (took off 40kg) and the difference between free length and the length on the car, and I got 117 lbs/inch and using a suspension frequency calculator that gives me 1.09Hz or 65cpm.
I just had a chat with Coil Springs in Sheffield about these figures, and he reckons that the problem is the B4s and not the springs. He said that he could make me softer springs but it won't make much difference because the forces that I am feeling are coming through the shock and not the springs.
So what should I do?
Bilstein are just going to say that I am used to knackered shocks and now it is the way it is supposed to be. That's what it says on their FAQ.
Are genuine Peugeot shocks going to be any better?
I am currently tempted to buy a sheet of thick rubber and cut a shape out that I can stuff between the top of the strut and the inner wing/tower as I can't really think of anything else to do.
What would happen if I did buy softer front springs? The car does seem a bit understeery compared with previous Peugeots I've had and think it could go even softer on the front.
My understanding is that if you have a shock that is much harder than the spring then it can jack itself down until the spring hardens up so you achieve nothing. Also I suppose that a tougher spring will be better at forcing itself down into potholes whereas a weaker spring just won't overcome that tough shock absorber and the whole car drops into the hole (to be honest it already feels like that. Is this true or rubbish?
I would really like to waft about in comfort and I'm not really too interested in cornering and roll doesn't bother me. I have always had soft rolling cars and that's how I like them.
Any thoughts are appreciated. Thanks.
The suspension has always been a little firm on it for a French car with very flat cornering, but last year it started to bounce a bit on certain roads and it scored an MOT advisory for leaking front shocks, so I did a little research and someone was saying that the Bilstein B4 is a comfortable shock, and to be honest it was the only "quality" name that I recognised and not much more expensive than the cheapest. So I bought and fitted them.
After a year the suspension is starting to annoy me.
On speed bumps it's okay, and on smooth motorways it's okay.
Around town it's terrible with small bumps shaking the whole car. On block paving I can feel every block and if the council has put a high grip surface I can feel it.
I have 225/55R16 winter tyres on it the moment with 32psi in them, and in the summer 225/50/R17. That doesn't seem to make any difference.
I also did a little research on the car. First I put it on a DVLA weighbridge and got 960kg on the front and 800kg on the back (the boot wasn't empty and a full tank).
Next I got another used spring with the same colour codes on it and measured the spring rate. Basically I used the weight of the car minus the weight of wheel, tyre, strut, hub and brakes, so 440kg (took off 40kg) and the difference between free length and the length on the car, and I got 117 lbs/inch and using a suspension frequency calculator that gives me 1.09Hz or 65cpm.
I just had a chat with Coil Springs in Sheffield about these figures, and he reckons that the problem is the B4s and not the springs. He said that he could make me softer springs but it won't make much difference because the forces that I am feeling are coming through the shock and not the springs.
So what should I do?
Bilstein are just going to say that I am used to knackered shocks and now it is the way it is supposed to be. That's what it says on their FAQ.
Are genuine Peugeot shocks going to be any better?
I am currently tempted to buy a sheet of thick rubber and cut a shape out that I can stuff between the top of the strut and the inner wing/tower as I can't really think of anything else to do.
What would happen if I did buy softer front springs? The car does seem a bit understeery compared with previous Peugeots I've had and think it could go even softer on the front.
My understanding is that if you have a shock that is much harder than the spring then it can jack itself down until the spring hardens up so you achieve nothing. Also I suppose that a tougher spring will be better at forcing itself down into potholes whereas a weaker spring just won't overcome that tough shock absorber and the whole car drops into the hole (to be honest it already feels like that. Is this true or rubbish?
I would really like to waft about in comfort and I'm not really too interested in cornering and roll doesn't bother me. I have always had soft rolling cars and that's how I like them.
Any thoughts are appreciated. Thanks.
The internet said said:
Bilstein list their B4 shocks as OE (Original Equipment) but they will appear slightly uprated over the standard items on your vehicle.
The only way to soften the dampers is put a lot of miles on them, maybe about 50k then they'll soften up a bit. 
The chap is correct, a car rides on it's dampers, not its springs so softening those will be worse than a waste of time.
OE dampers would be the only sure-fire way of returning it as it was when it left the factory.
You have gone from worn out dampers to slightly uprated ones so there will be a marked difference...
Simular situation on my E34 BMW. I'm pleased to say they have become less harsh now they have covered 6000 miles. How many have you done on yours?
By the way, the general consensus is that the B4s will be marginally harder than OEM. My car originally had Sachs/Boge which are soft (particularly after 120k miles...)
By the way, the general consensus is that the B4s will be marginally harder than OEM. My car originally had Sachs/Boge which are soft (particularly after 120k miles...)
I changed a set of knackered shocks and springs on a car with 100k miles and 195/60/15 tyres to B4s, Eibach springs (30mm lower) and went up to 205/45/17s and found the ride got better. Obviously every car is different and the B4 is a firmer shock but should be far less harsh and crashy than a knackered one.
Gassing Station | Suspension, Brakes & Tyres | Top of Page | What's New | My Stuff