[rothwem]

I used to have a Toyota Tacoma, and in the off-road community, droop travel is important for both rock crawling and the desert "go-fast" guys, since you get grip even when the vehicle is unweighted by a drip, or directly after a bump.

However, I don't have a good feel for road-going cars suspension, I never messed with my last BMW.

Anyways, I'm stuck between choosing Bilstein HDs and Bilstein Sports for the front of my xi wagon. The sports are shorter, so if I use the same spring for both, I get more bump travel with the Sports, and more droop travel with the HDs. I plan on using the HDs for the rear, since the ride height is perfect already and I want it to stay there, along with the OEM springs.

I know that back in the day before they invented sway bars, they would strap the travel of racecars. Basically, they would put a limiting strap that limited how far the suspension could droop, and that would take away grip from that end. For understeer, they'd strap the rear, for oversteer, they'd strap the front.

If I go with the Sports, will I be effectively "strapping" the front end of the car?

[Kgolf31]

You have to do some crazy things to fully achieve max droop on these shocks and cars.

If you're looking to replace purely for daily driving standpoint, don't worry about that.

I have coilover shocks, which have much less droop travel than what you're talking about and I've never had issues with extending full droop. Yes I've carried wheels in the air before (and have been on 2 wheels a couple times) but nothing that requires strapping the car or anything else of the sort to change handling dynamics of the car. Now we have valve adjustments internally within the shocks to control how fast the piston compresses and retracts.

[rothwem]

Originally Posted by Kgolf31

You have to do some crazy things to fully achieve max droop on these shocks and cars.

If you're looking to replace purely for daily driving standpoint, don't worry about that.

I have coilover shocks, which have much less droop travel than what you're talking about and I've never had issues with extending full droop. Yes I've carried wheels in the air before (and have been on 2 wheels a couple times) but nothing that requires strapping the car or anything else of the sort to change handling dynamics of the car. Now we have valve adjustments internally within the shocks to control how fast the piston compresses and retracts.

I'm not 100% sure what you're saying here.

First, I don't plan on strapping my car. I'm worried that the shock will act as a strap, artificially limiting travel on one end. Off-road, topping out a shock is just as bad as bottoming, though offroad vehicles have more unsprung mass than a road-going car.

So, with that said, is the travel more limited by the bushings and suspension bind than shock travel?

I want a suspension that handles well on a wide variety or surfaces (gravel, rough pavement, and smooth pavement) which means that I want balance and as much suspension travel as possible.

As far as anything being okay for daily driving--that's true. My 112,000 mile worn out suspension gets me to work just fine. A 1997 Hyundai Accent will (probably) get me to work too, as will a dump truck or a donk on 28" rims.

[Kgolf31]

Originally Posted by rothwem

I'm not 100% sure what you're saying here.

First, I don't plan on strapping my car. I'm worried that the shock will act as a strap, artificially limiting travel on one end. Off-road, topping out a shock is just as bad as bottoming, though offroad vehicles have more unsprung mass than a road-going car.

So, with that said, is the travel more limited by the bushings and suspension bind than shock travel?

I want a suspension that handles well on a wide variety or surfaces (gravel, rough pavement, and smooth pavement) which means that I want balance and as much suspension travel as possible.

As far as anything being okay for daily driving--that's true. My 112,000 mile worn out suspension gets me to work just fine. A 1997 Hyundai Accent will (probably) get me to work too, as will a dump truck or a donk on 28" rims.

Any OE replacement shock will have more travel that you can imagine.

Car will bind at the spring than at any bushing, it's common in the rear spring to bind (this causes the car to go up and tricycle).


Replace the shocks with OE and move on. Overthinking this.

[rothwem]

Originally Posted by Kgolf31

Replace the shocks with OE and move on. Overthinking this.

If I had a RWD E91, I'd have already done that. However, I've got an xdrive, and I don't feel like the did as good of a job on it and I'd like to improve it some.

Originally Posted by Kgolf31

Overthinking this.

Agreed.

I'd be less concerned with "droop travel" and more concerned with the fact that you're trying to mix/match dampers that aren't compatible with your OEM springs. The results of "improving it some" will come by way of properly fitted HD dampers, not shoehorned dampers meant for lowering springs into place just for the sake of doing so.

As it relates to your wagon, it would be of great benefit to you to take everything you know about "off-roading" suspension dynamics and throw it out the window. Since you have a limited set of parts to choose from as it is, the selection process at this point should be painfully simple.

[rothwem]

Originally Posted by FCobra94

Agreed.

I'd be less concerned with "droop travel" and more concerned with the fact that you're trying to mix/match dampers that aren't compatible with your OEM springs. The results of "improving it some" will come by way of properly fitted HD dampers, not shoehorned dampers meant for lowering springs into place just for the sake of doing so.

How do you figure that they’re not compatible? If the part physically fits, its “compatible”, it just might not be ideal. Then again, there’s a ton of aftermarket stuff that’s marketed as “compatible” and they get some major stuff wrong, especially as it relates to the x-drive cars.

Originally Posted by FCobra94

As it relates to your wagon, it would be of great benefit to you to take everything you know about "off-roading" suspension dynamics and throw it out the window. Since you have a limited set of parts to choose from as it is, the selection process at this point should be painfully simple.

I think there’s a lot to be learned by looking at other forms of motorsport. The off-road guys have figured out how to make a suspension work and grip the terrain at 100 mph over boulders a foot tall. Why throw away all of the lessons learned there when we struggle with the same things on road cars? Who doesn’t want more grip on bumpy roads? Who doesn’t want a more composed ride over expansion joints?

Especially in the BMW world, we get focused on this “track is everything” perspective, and start to believe that what is done in road racing is ideal. There are a lot of factors that differ between people driving on the track and people driving on the road.

[feuer]

Originally Posted by rothwem

How do you figure that they’re not compatible? If the part physically fits, its “compatible”, it just might not be ideal. Then again, there’s a ton of aftermarket stuff that’s marketed as “compatible” and they get some major stuff wrong, especially as it relates to the x-drive cars.



I think there’s a lot to be learned by looking at other forms of motorsport. The off-road guys have figured out how to make a suspension work and grip the terrain at 100 mph over boulders a foot tall. Why throw away all of the lessons learned there when we struggle with the same things on road cars? Who doesn’t want more grip on bumpy roads? Who doesn’t want a more composed ride over expansion joints?

Especially in the BMW world, we get focused on this “track is everything” perspective, and start to believe that what is done in road racing is ideal. There are a lot of factors that differ between people driving on the track and people driving on the road.

Unfortunately, playing with various shock lengths to achieve desired drop travel or compression travel will only get you so far as both will be limited to other suspension and drive train parts, like: control arm bushings, ball joints, tie rod ends and CV joints. So unless you looking into replacing all of those, like you was told before, you are indeed overthinking it a bit and depending on shocks alone the e91 will never grip the terrain at 100 mph over boulders a foot tall, will never offer more grip on bumpy roads, and be more composed ride over expansion joints.

[Kgolf31]

Originally Posted by rothwem

How do you figure that they’re not compatible? If the part physically fits, its “compatible”, it just might not be ideal. Then again, there’s a ton of aftermarket stuff that’s marketed as “compatible” and they get some major stuff wrong, especially as it relates to the x-drive cars.



I think there’s a lot to be learned by looking at other forms of motorsport. The off-road guys have figured out how to make a suspension work and grip the terrain at 100 mph over boulders a foot tall. Why throw away all of the lessons learned there when we struggle with the same things on road cars? Who doesn’t want more grip on bumpy roads? Who doesn’t want a more composed ride over expansion joints?

Especially in the BMW world, we get focused on this “track is everything” perspective, and start to believe that what is done in road racing is ideal. There are a lot of factors that differ between people driving on the track and people driving on the road.

Yes, people can go over boulders at 100 mph but look at the suspension when it hits dry pavement. Best thing to think of is trophy trucks.

This model line has been out for 10 years now. I'm sure the bases have been covered. Motorsports or not, stuff have been tested and proven around some pretty solid principles

[Cloud9blue]

Originally Posted by rothwem

I used to have a Toyota Tacoma, and in the off-road community, droop travel is important for both rock crawling and the desert "go-fast" guys, since you get grip even when the vehicle is unweighted by a drip, or directly after a bump.

However, I don't have a good feel for road-going cars suspension, I never messed with my last BMW.

Anyways, I'm stuck between choosing Bilstein HDs and Bilstein Sports for the front of my xi wagon. The sports are shorter, so if I use the same spring for both, I get more bump travel with the Sports, and more droop travel with the HDs. I plan on using the HDs for the rear, since the ride height is perfect already and I want it to stay there, along with the OEM springs.

I know that back in the day before they invented sway bars, they would strap the travel of racecars. Basically, they would put a limiting strap that limited how far the suspension could droop, and that would take away grip from that end. For understeer, they'd strap the rear, for oversteer, they'd strap the front.

If I go with the Sports, will I be effectively "strapping" the front end of the car?

You might want to update your knowledge on road car suspension...

[rothwem]

Originally Posted by feuer

Unfortunately, playing with various shock lengths to achieve desired drop travel or compression travel will only get you so far as both will be limited to other suspension and drive train parts, like: control arm bushings, ball joints, tie rod ends and CV joints. So unless you looking into replacing all of those, like you was told before, you are indeed overthinking it a bit and depending on shocks alone the e91 will never grip the terrain at 100 mph over boulders a foot tall, will never offer more grip on bumpy roads, and be more composed ride over expansion joints.

Why is it unreasonable to expect the shock to not be the limiting factor for suspension travel? That's all I'm asking for.

And I also don't think its unreasonable to ask for more grip on bumpy surfaces either...that's what a good suspension does. Sure, I might not be able to swallow up giant boulders, but it would be nice to be able to use the entire articulation range of the stock suspension (and axles).

[rothwem]

Originally Posted by Cloud9blue

You might want to update your knowledge on road car suspension...

google "droop limiters". They were used to bias the suspension for oversteer/understeer.

[Kgolf31]

So when have you experienced to date when your suspension has bottomed out or experienced full droop?

I ask this because you never have.

[Cloud9blue]

Originally Posted by rothwem

Why is it unreasonable to expect the shock to not be the limiting factor for suspension travel? That's all I'm asking for.

And I also don't think its unreasonable to ask for more grip on bumpy surfaces either...that's what a good suspension does. Sure, I might not be able to swallow up giant boulders, but it would be nice to be able to use the entire articulation range of the stock suspension (and axles).

You don't buy a e91 for Dakar rally...

Let me ask you this question. Do you plan on speeding across unpaved surface at +70mph in your e91??? If not, just leave it alone.

E9x, or any street cars, even most of unibody SUVs with independent suspension, isn't designed for the suspension to be effective at full droop... You are really asking the wrong questions at the wrong car here... Also, without some pretty chassis reinforcement, you will be bending shocks, control arms, and strut towers left and right if you plan on utilizing the full travel of your suspension at speed.

Good off-road suspension and shocks are incredibility overbuilt to absorb the insane amount of energy that they are being subjected too. Something our car will never be able to handle with the stock chassis.

[feuer]

Originally Posted by rothwem

Why is it unreasonable to expect the shock to not be the limiting factor for suspension travel? That's all I'm asking for.

And I also don't think its unreasonable to ask for more grip on bumpy surfaces either...that's what a good suspension does. Sure, I might not be able to swallow up giant boulders, but it would be nice to be able to use the entire articulation range of the stock suspension (and axles).

Because short shock, long shock, or no shock at all, the suspension travel, both front and rear, will be limited first and for most from the travel allowed by the control arm bushings, then ball joints, tie rods and CV joints on your car on both ends. That is why the control arms bolts need to be tighten up when the suspension is loaded by the natural weight of the car, not with the suspension hanging, not when the suspension is compressed.

[rothwem]

Originally Posted by feuer

Because short shock, long shock, or no shock at all, the suspension travel, both front and rear, will be limited first and foremost from the travel allowed by the control arm bushings, then ball joints, tie rods and CV joints on your car on both ends. That is why the control arms bolts need to be tighten up when the suspension is loaded by the natural weight of the car, not with the suspension hanging, not when the suspension is compressed.

Perfect.

This exactly what I was wondering. So the shock doesn't limit travel, rather its the suspension bind. So really, all I have to do is keep the shock length close to the OEM and I won't lose travel. And that's true for the xdrive cars too?

[rothwem]

Originally Posted by Cloud9blue

Let me ask you this question. Do you plan on speeding across unpaved surface at +70mph in your e91??? If not, just leave it alone.

THAT. WOULD. BE. AWESOME.

Actually, I did do some pretty gnarly gravel road driving when I was on vacation in Arkansas. 50 mph on a twisty gravel road was a fucking blast.

[Cloud9blue]

Originally Posted by rothwem

THAT. WOULD. BE. AWESOME.

Actually, I did do some pretty gnarly gravel road driving when I was on vacation in Arkansas. 50 mph on a twisty gravel road was a fucking blast.

Alright, whatever, do whatever you want and sell your car for dirt cheap when you are done abusing it... Since you clearly aren't listening to what everyone is trying to tell you.

[Camman]

I would not own a BMW if you are going to be off roading a lot. If you are experiencing full compression or full droop on your 328 on a regular basis, you are driving the wrong car.