DTM front suspension setup e30/e36

[johns14]

These are pics of the new suspension pieces. This is late DTM92 style.
It is the ultimate in light weight suspension, full geometry
adjustability, steering precision and stiffness. This suspension will work on e30 and e36 chassis race cars and even some E46 cars have used DTM struts and
suspension (see GTR class cars here in Germany).
These are used successfully on championship winning
rally cars under adverse conditions and they survive 24h Nuerburgring
races and even some front shunts without incident.


version that bolts into bottom of STOCK front subframe (for those
who do not want a custom subframe):
http://gallery.s14power.com/bilder/uniball/va_traeger.jpg


version with raised inner control arm pickup point (modified subframe
for the optimal control arm geometry for lowered cars. you dont have
to run such large spacers at the outer control arm pickup and it will
fit your rims easier):
http://gallery.s14power.com/bilder/userpics/10001/VA_GrA_11.jpg

spare parts:
http://gallery.s14power.com/bilder/uniball/austauschteile.jpg


control arm parts:
http://gallery.s14power.com/bilder/uniball/dtm_1.jpg

look here for more suspension pictures:
http://gallery.s14power.com/thumbnails.php?album=3

Please note that the control arms are SIDE specific -- in contrast
to some earlier setups which try to be universal meaning that they
try to fit them to both sides (which is not optimal).

John

[Eddy@ApexRaceParts]

that is the sexiest front control arm setup I've seen that can fit the e30 chasis.

[Steve J.]

Cool stuff, but whats with the welds on the subframe?

Have you thought about making a subframe from scratch? Its actually pretty simple, and would clean up that stuff very well.

Did you think about making the main control arm adjustable while still bolted in, or do you find it to be quick enough to unbolt it, change length and rebolt?

Is this stuff for sale, or are you just displaying it?

If I remember thelast post you had about a 8 or so months ago, these were just track day cars, right?

Now if someone could PLEASE find these rear trailing arms for me...

http://jaffster.com/misc/Misc/E36rsusp.jpg

[Steve J.]

Also, whose is this!? I assume the blacked out part of the wing has something to do with it?

http://gallery.s14power.com/bilder/userpics/10001/mz46.JPG

[johns14]

Cool stuff, but whats with the welds on the subframe?
Thanks. You have lots of questions.

The subframe shown is for an e30 m3 and thats the way its been
done, same as on the factory DTM cars. This is also where we bolt
the steering rack and blade adjustable ARBs and the motor mounts.

"whats with the welds?"
thats how the subframe is cut out and the inner pickup for the control
arm is raised up. That way we dont space the outer joint down so far.
Simple, cost effective, durable and most importantly: proven.




Have you thought about making a subframe from scratch?
Its actually pretty simple
As a one off, ok. I dont believe that is cost effective to do in any volume.
The stock subframe can be reinforced in all the relevant places
and you are good to go. This setup is tested on the Nordschleife which
is one of the most demanding tracks there is to test suspension setup and
of course the factory setup survived in many DTM races as well. So this
is a good basis to build on.

However, if you are in a position to engineer a subframe, you are
welcome to make a sample and send one to me for testing.
If there is potential, it could get tested on a 24h endurance car
(nuerburgring of course).





Did you think about making the main control arm adjustable while still bolted in, or do you find it to be quick enough to unbolt it, change length and rebolt?
we thought about it, and decided not to. once youve done a setup or 3,
its not a big deal and you make yourself charts with recordings for
baseline geometry measurements along with other data that many
already take like tire wear and temperature etc.




If I remember thelast post you had about a 8 or so months ago
was it 8 months ago already? wow time flies. I believe what I showed
then was a setup that was meant to work with a late DTM magnesium
lower strut housing. Most guys dont have these, and they are not very
cheap. They also use a different steering knuckle, there are several
versions available based on the strut used. We also use reinforced lower
steering knuckles with slightly modified pickup location for the stock
style strut.



these were just track day cars, right?
I dont know what someone elses definition of "track day" car is
nor what the point of the question was.
I may not know what the difference is given that Ive not seen
many track events in the USA. Although I was at sebring last year and
got to see some of the types of equipment used in "DE" cars and
"club race" cars. I also got to see a few pro cars.

If the point was to ask if these suspension parts have been tested
in racing, then the answer is yes. As stated above, test on the Nuerburgring.
this is pretty much identical to the DTM92 setup bar the strut housing
and BMW Motorsport didnt reinvent the wheel when the E36 M3 came
out. They grabbed parts from the same parts bin although there are
different struts and subframes available. The principles are all very similar.

For my car, this front axle setup is only one part of the equation.
I also run triple adjustable oehlins front and rear. Also in the works
is a race ABS, but it wont be from BMW.




Now if someone could PLEASE find these rear trailing arms for me...
If that is a request, then send email.

John

[=BA=]

Nice John. I was thinking about using aluminum wishbones in the rear for a E36 M3 without the lower springpad the other day. At wat cost figure are we looking when installing a kit like that, front and rear?

[Steve J.]

Thanks John.

Are you making these parts in a private shop, digging up old DTM parts and replicating them for guys to use on E30's to clubrace?

Or are you still working at the composites/manufacturing company doing factory BMW work?

What race series are you guys currently running?

[dak656]

holy rod ends in bending, Batman...

I know you say they've survived... but still, that's pretty much a design rule of suspension components...

[Steve J.]

holy rod ends in bending, Batman...

I know you say they've survived... but still, that's pretty much a design rule of suspension components...

Haha, sounds like what they used to yell over the loudspeakers at FSAE:

"If you use rod ends in bending you will not pass safety tech" :D

[TXBDan]

Can you guys explain or find a diagram showing "rod ends in bending"? What direction is a problem force in relation to the rod itself? I googled, but couldnt really find an explanation. I'm curious

[Steve J.]

I think this is for a ford focus, but it clearly shows the rod end in bending.

The rod end should really just have forces in compression/tension along that axis.

http://www.imagestation.com/picture/sraid56/peaef50e0091095d7827f91fb797f266f/fc743a26.jpg


Usually the only times you can get away with putting the rod end in bending is going with a rod end thats like 10x the required size.

If components are engineered properly you can use incredibly small hardware for most racecar applications. You usually want to add in a bit of safety factor though just to be safe. Extra 4-5lbs on a 2000lb chassis is worth if it it means a race will be finish rather than getting a DNF.

[dak656]

Can you guys explain or find a diagram showing "rod ends in bending"? What direction is a problem force in relation to the rod itself? I googled, but couldnt really find an explanation. I'm curious

A rod end (sperical bearing with a threaded extension) shouldn't ever be loaded in any direction other than the axis of the threaded extension. Because if you do, you're putting what is basically a threaded bolt in bending - which is a recipe for a failure.

The proper way to do that is to build a housing around a spherical bearing. You lose the adjustment factor of the threaded end, but there are way around that. One way I can think of for this application... rotate the spherical 90 deg (so the bolt that mounts the spherical goes up and down), then rotate the mount accordingly (keeping double shear) and then use pills to adjust the length.

[TXBDan]

Hrmm so any force not along the axis of the rod itself, eh? So it doesnt hurt or help if the axis the bolt goes through the bearing is rotated 90deg?

It seems like a tension/compression force on the rod and bearing would be the same to the bearing as an up and down force perpendicular to the rod if the bearing was oriented so the force was also perpendicular to the bolt through the bearing as well. Ie, so the bearing would take the load properly and not 'sideways'. I can my point is that if the bearing is round and the same all around, why does it care what direction a force comes from?

Or does the problem indeed only apply to forcing the bearing 'sideways'?

I'm surely confused, but its fun to play ME as a EE :P

[Steve J.]

Every engineer at our school, computer or electrical, nuclear, whatever, all took the same basic force/dynamics classes. Time to get your freshman books out ;)

The problem is the load on the threaded shaft, not necassarily the spherical bearing part of the rodend.

You also have to look at where your loads are coming from. Your tire is causing forces in many direction under dynamic loads. While turning it'll be compressing or pulling on those components, however you don't want the vertical displacement of your suspension to add any loads into the joints (aka rod end in bending). This is usually easier to spot on formula chassis where people used to use rod ends for everything, now most chassis got rid of most of the rod ends, thankfully. Used properly, you can usually get away with using very small rodends/bearings.

[TXBDan]

" The problem is the load on the threaded shaft, not necassarily the spherical bearing part of the rodend."

Right, thats what i'm clarifying. But if thats so, why the need for a bigger bearing instead of a bigger rod? I certainly see the problem w/ the rod, but not so much w/ the bearing itself.

[JamesM3M5]

Are these for sale, John? And can you make longer ones for E46 and E46 M3?? What is the price?

I understand the rod-end in bending issue, but when you consider the inner rod end is a foot away from the fulcrum with the force applied mere inches away, the bending load is quite low. No, it is not optimal, but also not a recipe for disaster like the yellow A arm Steve showed (not a BMW part of course). The single-shear lower mount at the steering arm is also not optimal, and stock BMW parts suffer failures occasionally during racing. I've also seen DTM BMW parts where there IS a rod end on the OUTER end of the arm put in bending. It was about a 20mm rod end, so it could take it for a good number of cycles. I'd never do that, but I could put up with the design John has shown above.

[Steve J.]

Here is the gtr subframe solution with the control arm brackets.

http://jaffster.com/misc/Misc/E46mockunder.jpg

[melmyers12]

Are these for sale, John? And can you make longer ones for E46 and E46 M3?? What is the price?

I understand the rod-end in bending issue, but when you consider the inner rod end is a foot away from the fulcrum with the force applied mere inches away, the bending load is quite low. No, it is not optimal, but also not a recipe for disaster like the yellow A arm Steve showed (not a BMW part of course). The single-shear lower mount at the steering arm is also not optimal, and stock BMW parts suffer failures occasionally during racing. I've also seen DTM BMW parts where there IS a rod end on the OUTER end of the arm put in bending. It was about a 20mm rod end, so it could take it for a good number of cycles. I'd never do that, but I could put up with the design John has shown above.

Single shear joints are designed that way to break cheap parts vs. breaking more expensive parts like your chassis for instance.

[Steve J.]

Mel, good point, however often in low-mid end aftermarket parts (off the shelf stuff for the most part thats not high priced high level custom applications) its usually just a poorly designed component ;)

Happy new years Mel, You planning to race in 07?

[e30-323ti]

Here is the gtr subframe solution with the control arm brackets.

http://jaffster.com/misc/Misc/E46mockunder.jpg

Steve, Does the control arm go into the end of the subframe??
If so, does it still use a "rod end" just rotated 90d from those shown earlier? (same orientation as the stock ball joints).
And if it does, the rod end would still be in a bending scenario, most probably at the rod end/control arm interface!?!?!

OR, does it use a high misalignment spherical bearing??
Looks a bit tight to fit any sort of machined control arm with a bearing into the end of the subframe though!?!?!

Have you got a pic of the control arms that go with it??

[Steve J.]

It uses a custom BMW Motorsport peice made for the GTR, uses a spherical balljoint from what I can see in the pictures. Not sure if its CNC or Cast, or if it was from a previous model in Motorsports garage. I think it uses the e30 front strut though.

Why did you put "rod end" in quotes?

This is the only picture I have uploaded where you can see the arms, 2004 Rolex "GTR" from PTG

http://jaffster.com/misc/Misc/gtrfront.jpg

[e30-323ti]

Are these for sale, John? ... What is the price?

I would also like to know thanks John.

[osborni]

I'm guessing, but it probably has the same setup as stock ball joints. The part in bending is a tapered rod that doesn't have any threads on it. You just don't want to bend a threaded bolt/rod as the notches for the threads add about a 4-10x stress riser.

This is why Aerospace bolts all have shoulders so when they are placed in single shear, it's not bending the threaded part.

[Steve J.]

I'd estimate the total package price to be $2-3k shipped form germany, maybe add in a couple hundred for rod ends.

I'd also suggest buying two sets, b/c if something breaks, you be screwed.

Idk know about it being just aerospace though, I think basically anything that is designed with specific hardware gets a proper fastener.

I actually don't think its a similar single shear balljoint like the stock subframe has, it might be a double shear clevis with a shimmed spherical bearing. I have to dig up a picture of it. I know there are some people here who have seen it first hand, I have only seen pics unfortunately, so they will hopefully chime in.

[johns14]

Ive havent visited this thread in a while.

What exactly is it that someone was complaining about
rod end in bending? The outer control arm joint that attaches to the
steering knuckle? or something else?

http://garage.s14power.com/data/512/medium/DSC00419.jpg

http://garage.s14power.com/data/512/medium/DSC00421.jpg


You do not need to buy 2 sets of control arms, but you might buy spare
rod ends so that you can service the supension. The setup shown for the
e30 is much stiffer than the original stock control arm.

Setups for e36/e46 are also available, e90 is in the works. if interested
send me an email m3pilot@gmx.de

PS: the CF body kit work shown on the mcoupe is available too.

John

[Steve J.]

Whats that yoke/clevis on the control arm linkage made of?

[CP Louie]

John:
I think that they are referring to the area below.
Chris

[Matt]

If that's supported by a similar spherical bearing at both ends, how can it possibly be loaded in bending?

[Steve J.]

Chris, that looks like a solid Yoke/clevis, I don't think thats what others were referring to before.

I think what was being referred to was the Subframe mount and the rear clevis mount which have rod ends.

They look beefy enough to withstand any bending loads being encountered. Also, I don't think anyone has reported failures yet from the application.

Many times designs at this level of motorsports can go against common principles, because they are made beefy enough to withstand the abuse (or lack of) that they see.

Its more of a problem in formula/prototype applications where you are pushing the limits with substantially higher lateral forces as well as aero downforce that create much harsher conditions, using hardware thats as small as possible with the required FoS.

Even for a competitive Mod racer though, you'd have to have a lot of testing and alignment time to make sure all the geometries of these components are right, because with more adjustments brings more chance for you to make it handle worse than before.

Adjustability does not necessarily mean it'll be faster...and in amateur racing, it actually usually means the opposite, without proper knowledge and testing/setup of the component.

[robweenerpi]

If components are engineered properly you can use incredibly small hardware for most racecar applications.

Those aren't cheap either. $40 dollar a peice tiny bolts are expensive to keep up with, and have to be torqued very accurately.

[Steve J.]

Those aren't cheap either. $40 dollar a peice tiny bolts are expensive to keep up with, and have to be torqued very accurately.

Got to pay to play :) (btw: Goodluck tomorrow BW!)

[Kevron]

John, sent you a pm and an email.

[SLR]

Cool stuff, but whats with the welds on the subframe?

Have you thought about making a subframe from scratch? Its actually pretty simple, and would clean up that stuff very well.

Did you think about making the main control arm adjustable while still bolted in, or do you find it to be quick enough to unbolt it, change length and rebolt?

Is this stuff for sale, or are you just displaying it?

If I remember thelast post you had about a 8 or so months ago, these were just track day cars, right?

Now if someone could PLEASE find these rear trailing arms for me...

http://jaffster.com/misc/Misc/E36rsusp.jpg

Dragging this out of the grave I know... but I think I can get ahold of these trailing arms, if you're really interested PM me

[Steve J.]

Why am i not surprised with a PTGM3 user name...ex-ptg employee? :)

Actually i had sourced some, but they were not worth the expense, plus if I needed replacements it would be hard to do. So i just did bearings in the stock M3 trailing arm.

Thanks though!

[JS154]

Cool stuff, but whats with the welds on the subframe?

Have you thought about making a subframe from scratch? Its actually pretty simple, and would clean up that stuff very well.

Did you think about making the main control arm adjustable while still bolted in, or do you find it to be quick enough to unbolt it, change length and rebolt?

Is this stuff for sale, or are you just displaying it?

If I remember thelast post you had about a 8 or so months ago, these were just track day cars, right?

Now if someone could PLEASE find these rear trailing arms for me...

http://jaffster.com/misc/Misc/E36rsusp.jpg

I think you're looking at a $15,000 Metalore axle shaft right there.

If you want to buy one for the other side, that will be another $15,000.

[FredK]

Soooo, that's not cad plating, it's gold plating? :D

That is achingly beautiful, though.

[TOOLEAN]

Where does that diff cooler ducting go? Looks like it goes into the cabin, no??

[Steve J.]

I believe the side window duct is the inlet for the cooler.

As for the Axles, you can get them from Cartridge Limited :)

[SLR]

Why am i not surprised with a PTGM3 user name...ex-ptg employee? :)

Actually i had sourced some, but they were not worth the expense, plus if I needed replacements it would be hard to do. So i just did bearings in the stock M3 trailing arm.

Thanks though!

Heh, I'm actually not an ex-PTG guy, just fell in love with their cars at Sebring when I was 18 or so, and have always wanted my own replica.

But actually those trailing arms are a factory BMW Motorsport piece. I even used to have the part number in a Teilekatalog somewhere, but cant find it.
From BMW when available they were something like $4500 each. They are aluminum I believe but might be magnesium??

They were standard pieces on all the Motorsport STW/GT chassis' from 1995 to 1999 along with the drool-inducing unobtainable-for-mere-mortals Moton 60mm inverted dampers:
http://i254.photobucket.com/albums/hh100/rolfos/S42%20BMW%20STW/Dscn5848.jpg
http://media.dtmpower.net/gallery/photos/121/dscn0709.jpg


I took a look under a Z4 Motorsport at the Nurburgring a few years ago and it appeared to be using the same trailing arms as well so there is a chance they are even still available direct from BMW M.

[Steve J.]

Its in my Motorsport catalogs, but the Z4 seems to be a different part. The problem was not knowing what it was, but where to find them for sale :)

I'd also take my Ohlins over those dampers ;)

[NeilM]

http://i254.photobucket.com/albums/hh100/rolfos/S42%20BMW%20STW/Dscn5848.jpg

Damn, that's one sexy threaded camber adjustment.

Neil

[Fair]

They were standard pieces on all the Motorsport STW/GT chassis' from 1995 to 1999 along with the drool-inducing unobtainable-for-mere-mortals Moton 60mm inverted dampers:
http://i254.photobucket.com/albums/hh100/rolfos/S42%20BMW%20STW/Dscn5848.jpg
http://media.dtmpower.net/gallery/photos/121/dscn0709.jpg


I took a look under a Z4 Motorsport at the Nurburgring a few years ago and it appeared to be using the same trailing arms as well so there is a chance they are even still available direct from BMW M.

Not trying to nit-pick but those cannot be 60mm inverted shafts... because as you can see they are considerably smaller than the clearly marked 60mm ID springs that are used on them. Not saying Moton didn't make a 60mm inverted shaft at some time (I've sure never heard of one, but anything is possible), but its not the one shown in that pic. They do look pretty slick though.

This is a 60mm inverted strut shaft. It uses 90mm Id springs and is on an EVO rally car:
http://vorshlag.smugmug.com/Product-Pictures/AST-5300-Shocks/Image34/517014511_6gXEk-M.jpg http://vorshlag.smugmug.com/Product-Pictures/AST-5300-Shocks/Image3/517018408_zvuKj-M.jpg

I've held these "Jumbos" in my hands (that's what AST calls them) and they indeed have HUGE shafts. Not what you'll see on a circuit/road race car (massive, massive overkill), but they are super strong work great for use in jumps/rally cars. :)

Cheers,

[SLR]

Not trying to nit-pick but those cannot be 60mm inverted shafts... because as you can see they are considerably smaller than the clearly marked 60mm ID springs that are used on them. Not saying Moton didn't make a 60mm inverted shaft at some time (I've sure never heard of one, but anything is possible), but its not the one shown in that pic. They do look pretty slick though.



I would guess they must be 50mm then, at least if thats a 5mm gap all the way round.... for some reason I thought I'd heard they were 60

Funny thing, as far as I can gather, Moton doesnt even offer inverted struts anymore.


Oh and here's a great pic of that trailing arm for anyone interested:
http://img.photobucket.com/albums/v249/freethinker41/stwe36lg.jpg

I found the catalog and there was a steel version from '92+ and Aluminum '97+

-Sean

And a nice shelf full of them:
http://img.photobucket.com/albums/v249/freethinker41/bmwSTWparts06lg.jpg

[RacerX]

I would guess they must be 50mm then, at least if thats a 5mm gap all the way round.... for some reason I thought I'd heard they were 60

Funny thing, as far as I can gather, Moton doesnt even offer inverted struts anymore.


Oh and here's a great pic of that trailing arm for anyone interested:
http://img.photobucket.com/albums/v249/freethinker41/stwe36lg.jpg

I found the catalog and there was a steel version from '92+ and Aluminum '97+

-Sean

And a nice shelf full of them:
http://img.photobucket.com/albums/v249/freethinker41/bmwSTWparts06lg.jpg

They're probably 45ish assuming Moton did not make the shafts and such. The kewl factor in all that is the upper portion/topmount adjuster set up anyway. Inverted struts kick ass of course but yeah, as Terry said, I don't think they do inverted anymore.

Love the TA's, very nice.

Cheers.

[SA E30]

I wouldn't mind one of those steering racks.

[Fair]

Yea, as Jack mentioned they look more like 45mm inverted shafts... for reference these are the common strut shaft sizes:

Non-inverted:

22mm (almost all non-inverted struts use this shaft size)

Inverted:

40mm (most inverted Bilstein stuff)
45 mm (pretty common for inverted struts outside of Bilstein, like AST 5000, Ohlins, other brands)
50mm (rare for AST and a very few others)
60mm (extremely rare AST and I've never heard of anyone else)


Those trailing arms are HAWT... :cool