1991 BMW 318is rally cross build

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formyhealth

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Thomas Kimsey


Tight and loose conditions favor FWD, faster stuff favors RWD.

Why is that do you think?

Tighter stuff is easier in Fwd due to it being easier to change direction. Putting the power down while turning. It is not until you give RWD the space to change direction(and put power down) is it viable.

RWD will always be the slowest in Rally cross because they dont give us any room to stretch our legs!.

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Thomas Kimsey

Tighter stuff is easier in Fwd due to it being easier to change direction. Putting the power down while turning. It is not until you give RWD the space to change direction(and put power down) is it viable.

RWD will always be the slowest in Rally cross because they dont give us any room to stretch our legs!.

Interesting, that all makes sense, it'll be fun trying to keep up with the FWD cars when I go out there.

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formyhealth

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Thomas Kimsey

Tighter stuff is easier in Fwd due to it being easier to change direction. Putting the power down while turning. It is not until you give RWD the space to change direction(and put power down) is it viable.

RWD will always be the slowest in Rally cross because they dont give us any room to stretch our legs!.

Interesting, that all makes sense, it'll be fun trying to keep up with the FWD cars when I go out there.

Good luck with that, in our region the AWD cars cant even keep up with the FWD guys. Maybe its different out there by you though.

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Thomas Kimsey

Good luck with that, in our region the AWD cars cant even keep up with the FWD guys. Maybe its different out there by you though.

I'm up for a challenge! (though I've never raced before..)

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formyhealth

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wvonkessler

Yup, but here's the badass Reconsales M - M3 Compact Cup - S14 engine with sequential gearbox:

Oh god that's sexy, is it yours? I am slightly envious I must say.. Sequential gearbox you say? Sheesh what a dream kit for me.

I've only got a ti shell right now. But it's white and is the "M" package. So no. I'm quite envious too.

---

"Talk about drugs. Driving a car like that, going that fast, it’s like all the drugs at once." - Tommy Byrne

"Now, Pinky, if by any chance you are captured during this mission, remember you are Gunther Heindriksen from Appenzell. You moved to Grindelwald to drive the cog train to Murren. Can you repeat that?" - The Brain

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wvonkessler


I've only got a ti shell right now. But it's white and is the "M" package. So no. I'm quite envious too.

I've always really admired those ti's, my uncle had one for a while and I had a soft spot for it.

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formyhealth

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john vanlandingham

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formyhealth
Thanks I agree with you, I've got plenty of paint runs already so I am well on my way to making it look half assed. You're actually the guy that brought me to this site, I saw a build thread that Dave Kern did with regards to that suspension you built, nice looking kit!

Danny

OOh that's kewl..Dave is a real good guy..Crazy in a good way and no bullshit, no backstabbin...and good analysis--ya know? When we were doing that I said OK we have to try some things and so we did, Then he thought "whaddya think of maybe....." so we tried some different things...
Not moaning and butt-hurt all over the World Wide Net..

You know what the back axle ratio is on that thing?

Yeah, read through his whole build, don't know him personally but he seems sharp for sure. Ratio on mine? it's a 4.10 open, looking for a 4.10 LSD for all the torques.

Honestly you may be fine and/or better off with a different ratio - I run a 3.91 (small case) LSD for rallycross, and a 3.73 (medium case) LSD for stage. There have been almost no times where I've wished for shorter gearing, especially with the Conforti chip adding a higher redline. 4.10 LSD is fairly rare since (IIRC) they only came in the 318is from 1991, whereas the 3.73 LSD is pretty easy to find off the 6cyl cars made over many years.

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irish44j


Honestly you may be fine and/or better off with a different ratio - I run a 3.91 (small case) LSD for rallycross, and a 3.73 (medium case) LSD for stage. There have been almost no times where I've wished for shorter gearing, especially with the Conforti chip adding a higher redline. 4.10 LSD is fairly rare since (IIRC) they only came in the 318is from 1991, whereas the 3.73 LSD is pretty easy to find off the 6cyl cars made over many years.

Thank you for the advice, do you have an M42 engine or a 6 cyl?

I was also interested in the 3.73 as you said, they are a lot more prevalent. I noticed from the calculator that it only makes a roughly 6 mph difference in 2nd gear @6,500 rpm if I went with a longer ratio. (Meaning +6 mph with a 3.73 vs. a 4.10 or 65 MPH with a 3.73 vs. 59 MPH with the 4.10)
So that doesn't seem to bad, should still allow for a good acceleration rate.

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paperpaper
4.10 lsd is the stuff. you need all you can get with the M42. Ditch the steering rack. make it happen with 2.7 to 1 z3 rack. you cannot go fast without it. (unless you dont like to go sidewaze) If you are worried about the puddle ditch the power steers all together. especially with your light front end its not needed on course. and get your self race size steering wheel. the tractor trailer wheel bmw ships is very nice and cozy but seriously big.

Ditch at least the rear sway bar. Its seriously un-nessasary in the car. even with the lighter m42 i bet the rear will be way too stiff. Plus you are pissing away loose surface traction. I just pulled the front bar from my rx car and its great. need all the bite you can get.

I'd agree with Dan on the e36 rack (it really doesn't matter if it's from a Z3 or regualr e36, the difference is minimal and regular e36 racks are substantially cheaper and easier to find at pick and pulls). I couldn't imagine using a stock e30 rack (especially with the stock steering wheel). Also you will want to drop the steering column angle by cutting out the safety bolts near the top and putting in some spacers and new bolts to give the wheel a lower angle rather than the school-bus angle. This will be especially important once you're caged, since you will likely need to put the seat lower than stock unless you have a very short torso.

I personally kept power steering and have never regretted it. I've never had problems with it leaking/breaking/running out of vacuum - even when doing the occasional autocross with the car. I see no reason to delete it unless you just want to tone your biceps or something.

As to sways - if you're on stock suspension (haven't read through this entire thread) you may want to keep the sways for the time being (they're not very big anyhow). I have both sways deleted, but I'm runing 240# linear springs up front and e36 M3 springs in the back so the added stiffness eliminates the need for sways. Stock springs and no sways will make the car unweildy on packed/paved surfaces at least.

In any case, nice to see another M42 built. I keep on thinking about swapping to M20 or M50/2, but keep on asking "why?" seeing as the car is so well-balanced with the M42 and really not giving up much power against the smaller sixes anyhow. So far in 5 seasons of rallycross and one rallysprint, no 6cyl e30 has beaten me (in about 100 attempts)....so the M42 isn't "too slow" or "not powerful enough" by any means. 318's dance intuitively on course while the sixer e30s require more work (I've driven a number of events in well-prepped 325s and road-race a 325e).

In any case, if you haven't already you may want to check out my build thread (and Dan's) on GRM or R3vlilmited. I haven't reinvented the wheel but five years of putting this car together you may find some tips and ideas that would come in handy, plus some 318/M42-specific information.

Looks like you have a good start on this build though, so will be interested to see how it goes! May want to consider doing a carbon copy of the thread on GRM or R3V where you'll get more e30-specific comments/advice (though less rally-specific comments).

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wvonkessler
Proper white wheels:

proper rally wheels are ones where you can't tell WHAT color they are under all the mud

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formyhealth

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irish44j


Honestly you may be fine and/or better off with a different ratio - I run a 3.91 (small case) LSD for rallycross, and a 3.73 (medium case) LSD for stage. There have been almost no times where I've wished for shorter gearing, especially with the Conforti chip adding a higher redline. 4.10 LSD is fairly rare since (IIRC) they only came in the 318is from 1991, whereas the 3.73 LSD is pretty easy to find off the 6cyl cars made over many years.

Thank you for the advice, do you have an M42 engine or a 6 cyl?

I was also interested in the 3.73 as you said, they are a lot more prevalent. I noticed from the calculator that it only makes a roughly 6 mph difference in 2nd gear @6,500 rpm if I went with a longer ratio. (Meaning +6 mph with a 3.73 vs. a 4.10 or 65 MPH with a 3.73 vs. 59 MPH with the 4.10)
So that doesn't seem to bad, should still allow for a good acceleration rate.

I'm M42 (originally M10). Also keep in mind your tire choice will affect your gearing. I have two different sizes of gravels (185/65/14 and 175/70/14) and my winter tires are 185/70/14 with streets being 205/50/15s. Chances are you won't be running stock tire size in rallycross if you use gravel tires, so account for that when doing gearing calculations.

Also find out how fast the courses local to you are. WDCR I regularly hit the limiter in 2nd with the 3.73 or 3.91, and that's WITH a higher redline than stock. Our courses are fast and open so the longer gearing is good to save shifts to low 3rd where the M42 is kind of gutless. If your courses are tighter and slower near you, the higher ratio may be better.

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irish44j

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Yeah, read through his whole build, don't know him personally but he seems sharp for sure. Ratio on mine? it's a 4.10 open, looking for a 4.10 LSD for all the torques.

Honestly you may be fine and/or better off with a different ratio - I run a 3.91 (small case) LSD for rallycross, and a 3.73 (medium case) LSD for stage. There have been almost no times where I've wished for shorter gearing, especially with the Conforti chip adding a higher redline. 4.10 LSD is fairly rare since (IIRC) they only came in the 318is from 1991, whereas the 3.73 LSD is pretty easy to find off the 6cyl cars made over many years.

Now that's nice but since you didn't put your first and last name--as is the one inflexible rule on this forum----we don't know who you are, or--since you didn't put you city and state (or Province) as is part of that same rule---we don't know where you are...and what you've done..
Reason I say that is cause the Intra-webz if swarming with all sorts of people and all the words look the same just one letter after another so the only way to weigh the words is by knowing who we're talking to, where they're from and what they've done..

I think this guy has a 4 cylinder..Lemme go look, OK,. Be right back.

Ok I'm back..Lookie at the piccie:


Welllp that thar shooooore looks like a 4 to me..In fact it looks just like the one I tore down just so I could measure the fawk outta everything with my trust super accurate electronic Very-nears..
Early version was 1800, later 1900. Not a particularly rip snortin' a-rootin and a-tootin' stump pulling, devastation wreaking motor (although plenty of potential just lurkin...brough ha ha!!!)
So one that seems like it could use some help making the carro scoot.

There is a pretty common correlation between engine size (assuming they kinda run and are no unusually big dogs), tire size overall and end use of vehicle--and final drive...

Now for grass-o-cross makes zero difference...its just more fun if a car has a bit of yank to it..
But for stage rally where 95% of what we do is 25mph to 90mph again and again and again all weekend...pretty typically a 2,0 motor making some beans on 13/14" tire might have 4.88 gears and same on short 62cm 15" tires we'd expect to see about 5,0 to 5.15 final drive..
Been that way for decades...
Of course that presumes a gearbox with ratios intended to do 25 to 90...not 30 km/hr oder vollgas immer gerade aus auf der autobahn! and mid-range sacrificed for top speed.

So welcome aboard and all but man to say "3.73 (medium case) LSD for stage. There have been almost no times where I've wished for shorter gearing" is well sehr interessant, junge..

Maybe explain not what--you just said what, but 'splain to the Oh Pea and me : why you don't wish any shorter. Do you not like acceleration? Short gearing = free acc. (that's pronounced like 'axe' , short for acceleration) Of course with the pick-up truck like 1st gear ration go short and you make the 1st gear suitable for "loading onto trailer only" gear but fawkit just go 2nd thru 5th...

But please why?

---

John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.

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irish44j

I'd agree with Dan on the e36 rack (it really doesn't matter if it's from a Z3 or regualr e36, the difference is minimal and regular e36 racks are substantially cheaper and easier to find at pick and pulls). I couldn't imagine using a stock e30 rack (especially with the stock steering wheel). Also you will want to drop the steering column angle by cutting out the safety bolts near the top and putting in some spacers and new bolts to give the wheel a lower angle rather than the school-bus angle. This will be especially important once you're caged, since you will likely need to put the seat lower than stock unless you have a very short torso.

I personally kept power steering and have never regretted it. I've never had problems with it leaking/breaking/running out of vacuum - even when doing the occasional autocross with the car. I see no reason to delete it unless you just want to tone your biceps or something.

As to sways - if you're on stock suspension (haven't read through this entire thread) you may want to keep the sways for the time being (they're not very big anyhow). I have both sways deleted, but I'm runing 240# linear springs up front and e36 M3 springs in the back so the added stiffness eliminates the need for sways. Stock springs and no sways will make the car unweildy on packed/paved surfaces at least.

In any case, nice to see another M42 built. I keep on thinking about swapping to M20 or M50/2, but keep on asking "why?" seeing as the car is so well-balanced with the M42 and really not giving up much power against the smaller sixes anyhow. So far in 5 seasons of rallycross and one rallysprint, no 6cyl e30 has beaten me (in about 100 attempts)....so the M42 isn't "too slow" or "not powerful enough" by any means. 318's dance intuitively on course while the sixer e30s require more work (I've driven a number of events in well-prepped 325s and road-race a 325e).

In any case, if you haven't already you may want to check out my build thread (and Dan's) on GRM or R3vlilmited. I haven't reinvented the wheel but five years of putting this car together you may find some tips and ideas that would come in handy, plus some 318/M42-specific information.

Looks like you have a good start on this build though, so will be interested to see how it goes! May want to consider doing a carbon copy of the thread on GRM or R3V where you'll get more e30-specific comments/advice (though less rally-specific comments).

Thank you for the info, to address a few things, firstly I am on R3V (same username) is your username the same there? I've been thoroughly reading your thread on GRM and you definitely know what your doing when it comes to M42 stuff. I didn't realize that the thread I've been reading the past few days was YOU.

Nice to meet you man, your build there is inspiring to say the least.

I purchased a 96' Z3 rack (last night) so that will go in when it arrives, also have a 210mm NRG wheel in there now which is pretty good for the price. I am interested in lowering the angle of the steering column, where would I find those safety bolts? are they easily visible if I remove the kick panel?

I'd like to keep the sways for now (so I don't feel like I wasted money on those powerflex bushings I bought) and also because I am on stock suspension as well.

Thank you again, I am stoked you are here too since I haven't gotten to the end of your thread yet.

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john vanlandingham

Now that's nice but since you didn't put your first and last name--as is the one inflexible rule on this forum----we don't know who you are, or--since you didn't put you city and state (or Province) as is part of that same rule---we don't know where you are...and what you've done..
Reason I say that is cause the Intra-webz if swarming with all sorts of people and all the words look the same just one letter after another so the only way to weigh the words is by knowing who we're talking to, where they're from and what they've done..

I think this guy has a 4 cylinder..Lemme go look, OK,. Be right back.

Ok I'm back..Lookie at the piccie:

Welllp that thar shooooore looks like a 4 to me..In fact it looks just like the one I tore down just so I could measure the fawk outta everything with my trust super accurate electronic Very-nears..
Early version was 1800, later 1900. Not a particularly rip snortin' a-rootin and a-tootin' stump pulling, devastation wreaking motor (although plenty of potential just lurkin...brough ha ha!!!)
So one that seems like it could use some help making the carro scoot.

There is a pretty common correlation between engine size (assuming they kinda run and are no unusually big dogs), tire size overall and end use of vehicle--and final drive...

Now for grass-o-cross makes zero difference...its just more fun if a car has a bit of yank to it..
But for stage rally where 95% of what we do is 25mph to 90mph again and again and again all weekend...pretty typically a 2,0 motor making some beans on 13/14" tire might have 4.88 gears and same on short 62cm 15" tires we'd expect to see about 5,0 to 5.15 final drive..
Been that way for decades...
Of course that presumes a gearbox with ratios intended to do 25 to 90...not 30 km/hr oder vollgas immer gerade aus auf der autobahn! and mid-range sacrificed for top speed.

So welcome aboard and all but man to say "3.73 (medium case) LSD for stage. There have been almost no times where I've wished for shorter gearing" is well sehr interessant, junge..

Maybe explain not what--you just said what, but 'splain to the Oh Pea and me : why you don't wish any shorter. Do you not like acceleration? Short gearing = free acc. (that's pronounced like 'axe' , short for acceleration) Of course with the pick-up truck like 1st gear ration go short and you make the 1st gear suitable for "loading onto trailer only" gear but fawkit just go 2nd thru 5th...

But please why?

lol you're a hoot! I wish I could find 4.55s or 4.88s (from the factory that is) I just don't have the green right now to drop on a custom unit. Also, I am GREEN meaning I have no rally experience so I figure stock and relatively low budget is best... for now any way.

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formyhealth

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john vanlandingham

Now that's nice but since you didn't put your first and last name--as is the one inflexible rule on this forum----we don't know who you are, or--since you didn't put you city and state (or Province) as is part of that same rule---we don't know where you are...and what you've done..
Reason I say that is cause the Intra-webz if swarming with all sorts of people and all the words look the same just one letter after another so the only way to weigh the words is by knowing who we're talking to, where they're from and what they've done..

I think this guy has a 4 cylinder..Lemme go look, OK,. Be right back.

Ok I'm back..Lookie at the piccie:

Welllp that thar shooooore looks like a 4 to me..In fact it looks just like the one I tore down just so I could measure the fawk outta everything with my trust super accurate electronic Very-nears..
Early version was 1800, later 1900. Not a particularly rip snortin' a-rootin and a-tootin' stump pulling, devastation wreaking motor (although plenty of potential just lurkin...brough ha ha!!!)
So one that seems like it could use some help making the carro scoot.

There is a pretty common correlation between engine size (assuming they kinda run and are no unusually big dogs), tire size overall and end use of vehicle--and final drive...

Now for grass-o-cross makes zero difference...its just more fun if a car has a bit of yank to it..
But for stage rally where 95% of what we do is 25mph to 90mph again and again and again all weekend...pretty typically a 2,0 motor making some beans on 13/14" tire might have 4.88 gears and same on short 62cm 15" tires we'd expect to see about 5,0 to 5.15 final drive..
Been that way for decades...
Of course that presumes a gearbox with ratios intended to do 25 to 90...not 30 km/hr oder vollgas immer gerade aus auf der autobahn! and mid-range sacrificed for top speed.

So welcome aboard and all but man to say "3.73 (medium case) LSD for stage. There have been almost no times where I've wished for shorter gearing" is well sehr interessant, junge..

Maybe explain not what--you just said what, but 'splain to the Oh Pea and me : why you don't wish any shorter. Do you not like acceleration? Short gearing = free acc. (that's pronounced like 'axe' , short for acceleration) Of course with the pick-up truck like 1st gear ration go short and you make the 1st gear suitable for "loading onto trailer only" gear but fawkit just go 2nd thru 5th...

But please why?

lol you're a hoot! I wish I could find 4.55s or 4.88s (from the factory that is) I just don't have the green right now to drop on a custom unit. Also, I am GREEN meaning I have no rally experience so I figure stock and relatively low budget is best... for now any way.

Wilson had posted this the other day on FB:
http://www.motamec.com/motorsport-parts/motamec-parts/lsd-differentials-crown-wheels.html

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rally gods would turn in their graves if they ever knew Lada's were now part of EU rallying!!!