With a new engine going in my M5 I was thinking of updating my wheels to some RSs purchased earlier this year. The RS 212s have to be rebuilt and was thinking about doing a popular up-sizing trick that a lot of e30-M3 guy do. They run a 212/197 combo which works out to 17x8.5 - 17x9.5. The "trick" here is to use the same 212 centers for the rear but a .5 inch wider lip and inner barrel to achieve the RS 197 spec. Real RS 197s are harder to find then 212s which is why up-sizing is popular.
So, anyone running staggered wheels/tires on their e28 ? I'm doing this for functional reasons as well as looks. e28s with skinny tires simply looks odd to me. When I see 528s on the road I hate it. But 535s and M5s with wider tires along side the boxy e28 body looks bad ass. As for the functional part.., the new engine will be around 340hp so thought that putting some more meat in the rear would be a good idea. Not sure about handling though. Might help with under-steer ?
Thanks.
Staggered set on M5
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mooseheadm5
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How about your tires?mooseheadm5 wrote:I'm running a 17x8/9 combo. It makes understeer worse unless you tune the suspension to compensate for the extra lateral grip afforded by the wider tires.
I run 16x7/8 but 225/50 all around. I haven't "tuned" the suspension (coilover/camber plates/swaybars) yet, but i've been more than happy with looks and performance.
Edit: my bad. This is M5 talk. "STFU Donny! You're out of your element!"
I am running a very slightly staggered set, Hankook RS3 on Fikse Profile 5S; 245/40/17 on 17x8.5 and 255/40/17 on 17x9. My 85 M5 was previously running 235/45/17 Potenza S-03 on BMW Style 32 Radials all-around. With 340 rwhp, the smaller/square set understeered moderately to heavy near the limit and would lose traction on the rears as the engine came on power in 1st and 2nd gear, a really issue in tight/slow corners. This may have been partly due to 4-5 yr old Potenzas? With the new, larger Hankooks the car is very neutral can be driven aggressively to the limits without worrying about the rear snapping loose. As long as you can keep the wheel/tire weights close to original specs, the handling should be great. my car tracks perfectly and has no unpleasant traits. FWIW, the rest of the suspension is Konis with Dinan springs and bars with GC links and a Brembo BBK. Good luck with your upgrade!
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mooseheadm5
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I run 16x7.5 and 16x8.5 with 225/245 right now and have set the suspension up to be almost neutral with that setup. I am now working on a 17x8/17x9 245/255 setup which will require a little retuning of the suspension.
What I look at is all other new performance cars. All of them that I have seen which are front engine, rear wheel drive use a staggered setup. The suspensions are all setup for that and if so the understeer can be dialed out with the correct swaybar, shock and spring setups. Also an adjustable rear subframe also really helps to dial out the understeer.
What I look at is all other new performance cars. All of them that I have seen which are front engine, rear wheel drive use a staggered setup. The suspensions are all setup for that and if so the understeer can be dialed out with the correct swaybar, shock and spring setups. Also an adjustable rear subframe also really helps to dial out the understeer.
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mooseheadm5
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I did forget to mention that I ran the same 16 wheel/tire dimensions on my old M5. As mentioned, understeer can be combatted with proper suspension tuning, but without changing things like shock valving, spring rates, sway bars, and rear camber/toe, you will have understeer issues on an E28 with staggered tires, especially with an M5 which is heavier up front than any of the other E28s.m535is wrote:I run 16x7.5 and 16x8.5 with 225/245 right now and have set the suspension up to be almost neutral with that setup. I am now working on a 17x8/17x9 245/255 setup which will require a little retuning of the suspension.
What I look at is all other new performance cars. All of them that I have seen which are front engine, rear wheel drive use a staggered setup. The suspensions are all setup for that and if so the understeer can be dialed out with the correct swaybar, shock and spring setups. Also an adjustable rear subframe also really helps to dial out the understeer.
Lots of comments on correct suspension tuning.. So, what specifics are we talking about other then tire pressure ?
Here's my setup
* Billie sports
* M-tech springs
* Bridgestone G-force KDWs (love these).
* Camber correct strut tops (OE).
* Dinan sway bars
* Stock sway bushings
* Adjustable links
So with the above what base line tuning should I try to achieve with standard wheels or a staggered setup ? Don't want to cause a thread war.., just looking for general guidelines and will fine tune once I get the car back on the road.
Here's my setup
* Billie sports
* M-tech springs
* Bridgestone G-force KDWs (love these).
* Camber correct strut tops (OE).
* Dinan sway bars
* Stock sway bushings
* Adjustable links
So with the above what base line tuning should I try to achieve with standard wheels or a staggered setup ? Don't want to cause a thread war.., just looking for general guidelines and will fine tune once I get the car back on the road.
Have you had the billie sports valved to match the M-tech shocks. If not, the car will understeer pretty much whatever you do. The rear billie sports are so soft they don't promote anything but understeer.
Are the Dinan bars adjustable? I can't remember.
Get yourself an adjustable rear subframe. I also ditched the camber correction mounts for Dinan fixed camber plates. Gives you more camber up front which is definitely helpful.
A lot can be done with swaybars, but you need to be able to adjust the rear suspension angles and damping adjustments help a lot too. You will know you have gotten the suspension dialed in correctly when you can adjust 1 or 2 psi on tire pressure and feel a difference.
Are the Dinan bars adjustable? I can't remember.
Get yourself an adjustable rear subframe. I also ditched the camber correction mounts for Dinan fixed camber plates. Gives you more camber up front which is definitely helpful.
A lot can be done with swaybars, but you need to be able to adjust the rear suspension angles and damping adjustments help a lot too. You will know you have gotten the suspension dialed in correctly when you can adjust 1 or 2 psi on tire pressure and feel a difference.
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Coldswede
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I fully agree with this statement. However, I would like to say that experimenting with sway bars should be done in the Fine tuning stage If your trying to increase your spring rates with your sway bars. Your doing it wrong! Get it dialed in with springs, shocks, camber, caster, alignment, tire width and sidewall stiffness and when your "This close" play with adjusting one side of the sway bar and tire air pressures. Keep a good record of what you do and how it reacted.A lot can be done with swaybars, but you need to be able to adjust the rear suspension angles and damping adjustments help a lot too. You will know you have gotten the suspension dialed in correctly when you can adjust 1 or 2 psi on tire pressure and feel a difference.
Oh! You will not be done this weekend.
Nope.., mounted them as-is. Is this a must ? I have a used set that I was thinking about having valved and can send them to Bilstein. Will they have the specs or do I need to dig them up for them ?Have you had the billie sports valved to match the M-tech shocks
The rear sway bar is adjustable and I have it set to the most aggressive/shortest setting right now. There are three holes, I have it in the last hole closest to the sway bar pivot.Are the Dinan bars adjustable? I can't remember.
Adjustable bolts/kit or is there an entire adjustable subframe. Also, what's the rule of thumb with adjusting the rear to dial out under-steer ?Get yourself an adjustable rear subframe
Ya, the OE plates don't allow that much camber but I had a set of Grunts plates in there and they failed in just a couple years due to the piss-poor roads in Los Angeles. Are the Dinan plates still available ? I heard they are the same as the OE camber correct plates ??I also ditched the camber correction mounts for Dinan fixed camber plates
Funny you say this because just prior to pulling my car off the road I could definitely feel when tire pressure was off. I was running 32 front and 34 rear.You will know you have gotten the suspension dialed in correctly when you can adjust 1 or 2 psi on tire pressure and feel a difference.
Bilstein HD/Sports (they're nearly the same valving) have really soft valving for the rears. I have no idea why. If you're sending a set in to get rebuilt, talk to Bilstein about what you have and your goals. I've heard they're generally good about knowing what settings work best with what setup. Failing that, you could just ask for BMW-Bilstein factory valving or even Dinan rear valving. BMW is a definite step up from stock HD/sport, Dinan is stiffer still from what I understand.Philo wrote:Nope.., mounted them as-is. Is this a must ? I have a used set that I was thinking about having valved and can send them to Bilstein. Will they have the specs or do I need to dig them up for them ?Have you had the billie sports valved to match the M-tech shocks
I do not like staggered wheel/tire combos. I'm not putting down ridiculous power on any of my cars, but the difference. Between a staggered set and a square set of 225/50s is amazing. The car is so neutral.
Also an RS212 barely fits on an E28 M5 or M535i with a 225/45/17. I don't know how you think you can make the wheel wider and get more rubber under there.
Also an RS212 barely fits on an E28 M5 or M535i with a 225/45/17. I don't know how you think you can make the wheel wider and get more rubber under there.
I would agree with the statement that you must play with spring rates first, but most of us do not use adjustable coil overs and cannot easily change spring rates so therefore you must go with a set of spring and tune from there.
The next point that needs to be tuned is the sway bars and since the Dinan bars are adjustable, let me teach you about roll-couple. Roll-couple is the difference between the stiffness in roll front to rear in a car. The comes from having a softer roll rate on one end of the car than the other. So for example you can put the front bar on full soft, furthest position from the pivot and the rear bar on full stiff, closest to the pivot. This will give you a roll-couple. You will then feel the car want to oversteer much more. I have played with this a lot and come to the conclusion that the front bar in the middle and rear on full still gave me the best combination.
Then you get to the shocks. You really can't tune the shocks properly until you get the roll rate correct or else you run in to the problem of over/under damping as you change spring rates and swaybar rates. With the setup I use, I have Koni Yellows, I run the rears between 3/4 and full stiff. The fronts I actually change more the the rear. If I am going to an auto-x I run them at full stiff to overdamp a little and help turn in. If I am going on track I run them at between 1/2 and 3/4 stiff to be able to handle curbs smoother etc. BTW, Konis have rebound adjustment, so you are really only adjusting how strong the shock resists lengthening. This really means you are controlling how much force goes into the swaybar during turn in, aka how fast or slow the car loads.
Now alignment settings. To get an adjustable rear subframe you can buy kits. Dinan used to sell one. The good ones are weld on and so you have to take the subframe out of the car and the inside trailing arm attachment is slotted vertically for camber and the outside is slotted horizontally for toe. You then spend hours aligning the car properly, so you need to make some friends at an alignment shop. I run factory rear toe on my car. I then run about 2.5 to 2.75 degrees of negative rear camber. I run this much static camber because I have set the rear suspension up so that it is very hard in roll. This means that without this much static rear camber I would wear only the outside edges of the tires in corners. In the front, more camber is better. The Dinan fixed plates are no longer available, but IE makes copies. I have seen both and the IE ones don't fit as well as the Dinan ones, and they all use the non-offset upper mounts which are about 1/2 the cost of the camber correction units. This gives you about .75 to 1 degree of camber on a stock car. My current lowering shows me at the 1.75 to 2 degree range.
I run 36psi all around and have perfectly flat tire wear both front and rear.
All of this gives me a neutral car in my view. But here is where we come to the largest point. Everyone has different driving styles. I have had people drive my car and say that it is way to loose and other who say that it still understeers too much. It is all a balance between your driving style and how you setup the car. So the real key is is you are looking for speed, you need to get the most adjustablity as possible and as much seat time as possible and get it to your liking. It probably took me about 6 months before I got the car to where I like it.
Now with the heavier motor, and looking into the different wheels I could be in for another 6 months or more.
The next point that needs to be tuned is the sway bars and since the Dinan bars are adjustable, let me teach you about roll-couple. Roll-couple is the difference between the stiffness in roll front to rear in a car. The comes from having a softer roll rate on one end of the car than the other. So for example you can put the front bar on full soft, furthest position from the pivot and the rear bar on full stiff, closest to the pivot. This will give you a roll-couple. You will then feel the car want to oversteer much more. I have played with this a lot and come to the conclusion that the front bar in the middle and rear on full still gave me the best combination.
Then you get to the shocks. You really can't tune the shocks properly until you get the roll rate correct or else you run in to the problem of over/under damping as you change spring rates and swaybar rates. With the setup I use, I have Koni Yellows, I run the rears between 3/4 and full stiff. The fronts I actually change more the the rear. If I am going to an auto-x I run them at full stiff to overdamp a little and help turn in. If I am going on track I run them at between 1/2 and 3/4 stiff to be able to handle curbs smoother etc. BTW, Konis have rebound adjustment, so you are really only adjusting how strong the shock resists lengthening. This really means you are controlling how much force goes into the swaybar during turn in, aka how fast or slow the car loads.
Now alignment settings. To get an adjustable rear subframe you can buy kits. Dinan used to sell one. The good ones are weld on and so you have to take the subframe out of the car and the inside trailing arm attachment is slotted vertically for camber and the outside is slotted horizontally for toe. You then spend hours aligning the car properly, so you need to make some friends at an alignment shop. I run factory rear toe on my car. I then run about 2.5 to 2.75 degrees of negative rear camber. I run this much static camber because I have set the rear suspension up so that it is very hard in roll. This means that without this much static rear camber I would wear only the outside edges of the tires in corners. In the front, more camber is better. The Dinan fixed plates are no longer available, but IE makes copies. I have seen both and the IE ones don't fit as well as the Dinan ones, and they all use the non-offset upper mounts which are about 1/2 the cost of the camber correction units. This gives you about .75 to 1 degree of camber on a stock car. My current lowering shows me at the 1.75 to 2 degree range.
I run 36psi all around and have perfectly flat tire wear both front and rear.
All of this gives me a neutral car in my view. But here is where we come to the largest point. Everyone has different driving styles. I have had people drive my car and say that it is way to loose and other who say that it still understeers too much. It is all a balance between your driving style and how you setup the car. So the real key is is you are looking for speed, you need to get the most adjustablity as possible and as much seat time as possible and get it to your liking. It probably took me about 6 months before I got the car to where I like it.
Now with the heavier motor, and looking into the different wheels I could be in for another 6 months or more.
That was a great post Rob! 
Right now I have an old set of Sumitomo HTRZs on them I think. Chris is right, tires are slim. All the tires available on tirerack right now are DOT-R and while I love that idea, I currently spend more time on the street than on the track in the car since I am still getting all the bugs out of the engine swap. This for me is the main driver of why I need to put 17" wheels on the car. Then I can run the 17x8 and 17x9 wheels with 245/255. Then I will put some RA-1s on the 16s. You know it is funny because in Germany there are both the Bridgestone Potenza S-02s and the Michelin Pilot SX MXX3s available.
You can pretty much run anything on the street -- staggered tires, skinny tires, 16. 17, 18, dubs, koni adjustables, Bilstein sports, adjustable camber plates, etc. it's about the style, look, and feel you want for commuting to work and sliding around the on ramp.
on the track, there are fewer choices if you want to go fast. I've tried many combinations of wheels and tires including staggered, 16 vs 17, staggered 16, etc. You want the largest front tire not only because of under steer but because it is such a heavy front end that tires get chewed up fast. I run 17x9 with 255 all around and there is no comparison to anything else except maybe 255 on 16" wheels. Staggered on the track has no advantages.
The shocks need to be matched to the springs and to your driving intention. This is probably the single most important adjustment to be made. There is no way that a single generic sport shock will work optimally with every spring out there. The cost of revalving is so little that you should just do it and try it.
There are at least 4 different damping rates that are set on each shock so there is no single stiffer or softer shock setting. Give Bilstein your spring rate and corner weight along with the application. I would recommend "street setup with occasion track". Ride quality will be good (better than sports out of the box) and they will work great on the track. the track valving setup is really for a car with a cage. Without a cage the track valving isn't much better than street, and the ride suffers a lot.
To me a staggered setup on the E28 is for people who want the looks of less tire rather then more tire.
on the track, there are fewer choices if you want to go fast. I've tried many combinations of wheels and tires including staggered, 16 vs 17, staggered 16, etc. You want the largest front tire not only because of under steer but because it is such a heavy front end that tires get chewed up fast. I run 17x9 with 255 all around and there is no comparison to anything else except maybe 255 on 16" wheels. Staggered on the track has no advantages.
The shocks need to be matched to the springs and to your driving intention. This is probably the single most important adjustment to be made. There is no way that a single generic sport shock will work optimally with every spring out there. The cost of revalving is so little that you should just do it and try it.
There are at least 4 different damping rates that are set on each shock so there is no single stiffer or softer shock setting. Give Bilstein your spring rate and corner weight along with the application. I would recommend "street setup with occasion track". Ride quality will be good (better than sports out of the box) and they will work great on the track. the track valving setup is really for a car with a cage. Without a cage the track valving isn't much better than street, and the ride suffers a lot.
To me a staggered setup on the E28 is for people who want the looks of less tire rather then more tire.
Sorry, but there is no way to fit a 255 on the front of an E28 unless you are going to run adjustable coil overs with 4 inch diameter springs. If you want to run an off the shelf stock replacement spring a 245 up front is the most you can ever hope for and even that you have to have the offset correct to the mm. As for a staggered setup not being useful on track, please explain to me then why so many sports car racers use staggered setups. Simply put you want to fit the largest tires possible under the car period. If you can fit 255s all around and that is the largest you can go, great, but if you can put 255s out back and 245s or 235s up front then you should do this and set up the suspension accordingly, as most race teams do. Thinking that bigger is better on the front to get rid of understeer is only bandaiding the problem. The fact of the matter is, the larger the tire on the front axle, the more numb the steering becomes, especially if the suspension is not designed for it. Yes you fix, or partially fix the understeer issue, but you could have also done that with spring rate, roll bar and shock settings.
But like I have said before there are 2 keys. First is fitting the widest tire you have clearance for. The second is that each driver is different and therefore the way the car is setup is different for each driver, why do you think endurance racing is so challenging?
But like I have said before there are 2 keys. First is fitting the widest tire you have clearance for. The second is that each driver is different and therefore the way the car is setup is different for each driver, why do you think endurance racing is so challenging?