BMW Compact Build

Topi Wrote:
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> Mike Whitman's wife Bobby has one in the garage in
> N.M. Brand new, never rallied since built.... she
> found out horses are more fun than HP.
>
> - RWD rocks -
>
>
>
> Edited 1 times. Last edit at Apr 17, 2010 by Topi.


ummm HP = horsepower....?

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-Mark
www.nocoastmotorsports.net

Mark Wrote:
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> ummm HP = horsepower....?

So (1 hp) > (2+ hp)

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Grant Hughes

What are you guys using for an LSD? Or does it already have one?

And what's the gearing like on these?

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Ben Hetland
1973 Volvo 142 project car (with some cone-smashing on dirt in it's future, however)

"No. Rally Racing is a back alley sport filled with jackals, headhunters and thugs!"
-Pops Racer (Speed Racer movie)

www.utahrallygroup.com

1fastben Wrote:
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> What are you guys using for an LSD? Or does it
> already have one?
>
> And what's the gearing like on these?

These boys listen!
They're going to use the MA70, MkIII Supra unit just like we use on Xratties since I make adaptors for the half shafts, why the fawk not!!??

BMW gearbox ratios are a chapter unto themselves, don't ask, they make perfecrt sense in 'der heimat' aber im schotter ganz scheisse!
>
> "No. Rally Racing is a back alley sport filled
> with jackals, headhunters and thugs!"
> -Pops Racer (Speed Racer movie)
>
>
> www.utahrallygroup.com

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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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> What are you guys using for an LSD? Or does it
> already have one?
>
> And what's the gearing like on these?


If we go with the Toyota conversion, R&P up to the high 5.xx range are available thanks to all the rock crawlers running 35s. If I have to buy a R&P set to get going, I'll probably start out with a 4.88.

I'm not too sure what options are for LSDs, but my preliminary thought is to just weld it up for this year (i.e. cheap), and look at having a 2nd unit with a proper plated LSD for 2011.

Dave

john vanlandingham Wrote:
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> BMW gearbox ratios are a chapter unto themselves,
> don't ask, they make perfecrt sense in 'der
> heimat' aber im schotter ganz scheisse!

Ain't that the truth. Stock M3 gearbox has something like a 4.2 1st gear and a 1.0 5th. 3-4-5 are stacked pretty nice, but there's a wicked drop from 1st-2nd.

BMW diffs are really only available up to 4.27s in the US (medium case 188), though their motorsports division does make diffs up into the 5.xx range. For those you're talking $1000-1500 for the R&P, so I'm figuring that long term, converting to the Toyota stuff makes sense.

Dave

DaveK Wrote:
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> If we go with the Toyota conversion, R&P up to
> the high 5.xx range are available thanks to all
> the rock crawlers running 35s. If I have to buy a
> R&P set to get going, I'll probably start out
> with a 4.88.
>
> I'm not too sure what options are for LSDs, but my
> preliminary thought is to just weld it up for this
> year (i.e. cheap), and look at having a 2nd unit
> with a proper plated LSD for 2011.

Something wrong with the stock Toyota plated LSD? If I recall, it's around 120 breakaway torque. Both Cusco and Kaaz make them as well (2 way and 1.5 way ones anyhow). All three of those I got were plated LSDs with 4.3 final drives.

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Grant Hughes

NoCoast Wrote:
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> Something wrong with the stock Toyota plated LSD?
> If I recall, it's around 120 breakaway torque.
> Both Cusco and Kaaz make them as well (2 way and
> 1.5 way ones anyhow). All three of those I got
> were plated LSDs with 4.3 final drives.

IDK, I don't own at Toyota rear diff yet, I'm still waiting to see what the deal is with the one Aaron supposedly has. I figure if its an open diff, weld it up and call it good. If its a plated LSD to start with, maybe I'll try to cram a few more plates into it and call that good.

A 4.3 is just about perfect for a N/A track car based on speeds at HPR and PMI, with a top speed of ~130mph. For rally duty, a 4.88 will yield a top speed closer to 110.

BTW, I found a guy locally who's willing to set one up for me (and hopefully show me how its done) in return for a bunch of GTX spares I passed on to him.

Dave

I mean, look at how pretty that looks!

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Grant Hughes

Nice!
Aaron's was in the back of his car. Pretty sure.
I paid $60 for the two junkyard ones and $40 for that one that you borrowed that needs a rebuild. Takes about 20 minutes to get it out of the car typically.

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Grant Hughes

DaveK Wrote:
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> --------------------------------------------------
> -----
> > What are you guys using for an LSD? Or does
> it
> > already have one?
> >
> > And what's the gearing like on these?
>
>
> If we go with the Toyota conversion, R&P up to
> the high 5.xx range are available thanks to all
> the rock crawlers running 35s. If I have to buy a
> R&P set to get going, I'll probably start out
> with a 4.88.
>
> I'm not too sure what options are for LSDs, but my
> preliminary thought is to just weld it up for this
> year (i.e. cheap), and look at having a 2nd unit
> with a proper plated LSD for 2011.
>
> Dave


There's a smart boy.
Although be careful on the ratio, too short and first will be good for crawling up the ramps onto the trailer and nothing else.
Now if you had a dogleg first you could easily just skip 1st and use 2nd thru 5th

---

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.

john vanlandingham Wrote:
-------------------------------------------------------
> There's a smart boy.
> Although be careful on the ratio, too short and
> first will be good for crawling up the ramps onto
> the trailer and nothing else.
> Now if you had a dogleg first you could easily
> just skip 1st and use 2nd thru 5th

I tried to see if there were any replacement 1st gear kits for the BMW but didn't have any luck. It seems like even in factory trim, 1st is only really to get you going, and you'll never drop down into it again. With a torquey 3.0L on dirt, it should still be able to spin the tires in 2nd, which I think is in the 2.2-2.4 ratio range.

3.9 (common OEM BMW ratio), 1st = 32mph, 5th = 137mph
4.88 (toyota rock crawler), 1st= 26mph, 5th = 110mph

I'm not sure what the shift pattern is on my transmission...it didn't come with a shift knob with the handy diagram on it...

Dave

Once you get the Toyota/Bimmer rear end done, let me know. Right now we've got 4.1s, one with a factory LSD, the other with a Quaife. It is still fun.

Wilson

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"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

Figured I'd post some updates - been very busy with the car lately, hoping to have it running by the first week in December.

Kevlar being applied to the gas tank:



Floor pan felt pretty thin, so decided to add a couple layers of kevlar there too:



Macropoxy on the underbody:



Interior painted - used appliance epoxy spray cans:



New rear subframe and trailing arm bushings installed:



UUC lightweight flywheel replaces the craptastic heavy dual-mass unit.



Steering rack from a Z3 (14.5 ratio vs. 16.8 stock TI) installed along with new motor mounts:



Heaterbox trimmed to fit around the cage:



Dash trimmed to fit:



"New" engine finally dropped in:



Dave

Looking good!