S14 trans to 2.0 M10 block, I have questions

[Turb02]

First, I know I'll need to modify the tunnel, not that big of a deal but still time consuming. My question lies with the diff that I should match to this, and what clutch kit will work. My goal is ~300 hp and close to 260 tq, weekend track car that wil be driven on the hwy as well.

I know the M3 came with a 4.10 diff but it's not turbo so I wont need that high of ratio. I'm just not sure if the 3.91 will be too high. Should I look at a 3.64 LSD or even lower.

As for clutch kit, I want it to be comfy but with lots of clamp force, so I was looking at the spec II+. It can hold like 320 tq. Should I look elsewhere for a clutch kit?

Also can someone provide me with a picture of an assembled trans with the platform and support bar? I don't think the trans came with the appropriate shift platform/plate.

Thanks everyone, in advance!!

[peteinjp]

I've never driven a turbo 02 so take it for what its worth...... On my tii with its mighty 130hp I love the 4:10. I had the 3:91 and it was nice as well. With the turbo I'd go with the 3:64 for sure. You would have to have some big soft tires to keep the wheels from spinning with the kind of power your talking about and lower gearing. If your setup makes good power from down low- nice torque curve all the way up you wouldn't need the shorter gears which keep the car in the higher RPM range where smaller NA cars make power. And as usual it depends on how and where you want to drive.

[Turb02]

Thanks for the info. I was considering a 3.64 when I posted this topic but wasnt sure if a taller gear would be better. From my calculations, I should hit almost full boost at 3500-3800 rpm's.

Also, does anyone have a picture or a parts list with part numbers for the shifter platform and its associated parts (how it mounts to the trans)? Im not sure how it mounts...

[NickVyse]

First, I know I'll need to modify the tunnel, not that big of a deal but still time consuming. My question lies with the diff that I should match to this, and what clutch kit will work. My goal is ~300 hp and close to 260 tq, weekend track car that wil be driven on the hwy as well.

I know the M3 came with a 4.10 diff but it's not turbo so I wont need that high of ratio. I'm just not sure if the 3.91 will be too high. Should I look at a 3.64 LSD or even lower.

As for clutch kit, I want it to be comfy but with lots of clamp force, so I was looking at the spec II+. It can hold like 320 tq. Should I look elsewhere for a clutch kit?

Also can someone provide me with a picture of an assembled trans with the platform and support bar? I don't think the trans came with the appropriate shift platform/plate.

Thanks everyone, in advance!!

which m3 265 gearbox - US OD or Euro CR?

[Turb02]

US spec. Thanks. I really need to see the hardware and mounting configuration

[TobyB]

uhhh, so you're turboing an M10, and bolting up a S14 trans?

If you gave us the od ratio on the trans, we could be more help...

likewise, knowing what you'll redline the motor at will also help..

as would torque numbers... as would tire diameter... and... oh, hell, color?

but if it's like most US cars, it's significant. That would let you use

a taller diff- the 4.10 in the M3 really IS a good match for zip.

If you're going to try to match the diff for maximum top speed,

you'll probably end up in the 4.27 range with a .85 od, figuring that

terminal velocity of a 2002 with anything less than a Pratt and Whitney stuffed

in the trunk isn't going to exceed 140 mph.

Frankly, though, build the car first. Picking a ring and pinion is going to

be a minor expense.

As to clutch, look at E30 'performance' stuff- I seem to remember that it'll

bolt in, and the E30 has a lot more torque, which is all that a clutch cares

about. I can put 1000 horsepower through a stock 2002 clutch no problems,

but anything over 200 ft/lbs isn't going to work.

t

[Turb02]

uhhh, so you're turboing an M10, and bolting up a S14 trans?

Yes and yes.

If you gave us the od ratio on the trans, we could be more help...

likewise, knowing what you'll redline the motor at will also help..

as would torque numbers... as would tire diameter... and... oh, hell, color?

Not sure the relavance of the OD ratio of the trans, wont rev past 6800-7000, TQ I believe Ive listed in the first post but I will say ~260 to the wheels, might run 225/50/15 but for starters it will be 205's. Not sure on the color yet, might be a factory BMW color, not sure what model and year though.

but if it's like most US cars, it's significant. That would let you use

a taller diff- the 4.10 in the M3 really IS a good match for zip.

Being boosted, I dont see the 4.10 being a smart choice, + its not in a M3.

If you're going to try to match the diff for maximum top speed,

you'll probably end up in the 4.27 range with a .85 od, figuring that

terminal velocity of a 2002 with anything less than a Pratt and Whitney stuffed

in the trunk isn't going to exceed 140 mph.

Not going for max speed here. Looking for a dif that wont be a dog from a dig or redline at 100.

Frankly, though, build the car first. Picking a ring and pinion is going to

be a minor expense.

I agree but I figured I would get my parts list SOMEWHAT complete, and the diff is something that I need to figure out.

As to clutch, look at E30 'performance' stuff- I seem to remember that it'll

bolt in, and the E30 has a lot more torque, which is all that a clutch cares

about. I can put 1000 horsepower through a stock 2002 clutch no problems,

but anything over 200 ft/lbs isn't going to work.

t

Thanks, So the stock M3 flywheel will bolt up to the 2002's M10? What is the diameter of the M3 flywheel? Then the Spec Stage II+ ~should~ suffice? My question in this area was pointing towards the crowd to find out if there was a better alternative than the Spec clutch...

[TobyB]

Not sure the relavance of the OD ratio of the trans, wont rev past 6800-7000, TQ I believe Ive listed in the first post but I will say ~260 to the wheels, might run 225/50/15 but for starters it will be 205's

The overdrive ratio determines your final cruise rpms. What you're aiming for with power can get

you into the 130+ mph range, and that means that your top gear can either

be a cruising gear for the freeway OR it can be top gear at 6800 at flat out

top speed. All depends on the diff you choose...

Yes, sorry, I meant the 4.10 from the E30's... and with a .81 od out of an

E21, that makes 4th gear very zippy, and 5th ends up a little above stock 4th with a 3.64, so you get a fast car that doesn't drive you nuts when you drive

fast. But if you want to cruise at 2400 in 5th @ 70 , start looking for a 3.45...

There's one other big variable in all this- where does your turbo like to be

for maximum efficiency? For example- just an example, I'm old- fashioned

in what I know about turbos-

If you're running a big T4, you'll want to gear

up so you can spin the motor pretty fast, keeping a lot of flow through the turbo. I'm guessing, since you're talking about 7k, you'll have

a pretty open turbo, and thus want a lower (numerically higher) rear

to keep revs up.

But if you were to run a small A/R t3, you'll want to gear down so that you can

keep flow lower and not overflow the smaller passages in the turbo.

And you'll shift at a lot lower rpm than the big turbo. Kind of like an eta E30...

Check me on the E30 clutch stuff, but I recall that the E30 pressure plate bolts right

up to the stock 228mm flywheel. I think the 'sport' version from Spec or

Sachs or anyone reputable would probably hold up pretty well,

and not break the bank. The friction plate should probably be pretty

aggressive, too- but not a full- race version, because that won't last very long.

Good luck, and hope this helps...

t

[Turb02]

The turbo is a hx35 from a cummins, and it will boost from ~3500 to redline. The limit I posted (7000rpm) won't be seen that often, more of a personal rev limit for spirited shifting, which the turbo will be more than adequate.

That being said, what would you recommend, for diff ratio?

Thanks on the clutch info!

[TobyB]

I STILL like the 4.10, if your turbo's going to come in as late as 3500...

but I think you'd like a 3.91 just fine, and they're so much easier to come by,

especially as a 'get on the road and try it.'

I'd love to turbo an M10 sometime... good luck with it!

[Turb02]

Thanks for the tips. Im sure I can find a good condition 3.91 lsd fairly "local"

[Turb02]

Ok, so now that we've covered that, can we discuss a picture of the shift platform and its mounting hardware? THe one that came with the S14 trans, doesnt seem like its the right one. Granted I dont have any of the mounting bolts and stuff.

Any pointers for a parts list AND installed platform pictures (of where it mounts to the trans)?

[canadamatt]

Check me on the E30 clutch stuff, but I recall that the E30 pressure plate bolts right

up to the stock 228mm flywheel. I think the 'sport' version from Spec or

Sachs or anyone reputable would probably hold up pretty well,

and not break the bank. The friction plate should probably be pretty

aggressive, too- but not a full- race version, because that won't last very long.

Good luck, and hope this helps...

t

Yep, most of the the swedish e30 dudes / 228mm run the sachs "618" pressure plate, and most seem to run the stock disk actually. And they run some sick numbers. The 618 is pricey though, I think around $400 by itself.

Matt

[Turb02]

That is expensive just for the pressure plate. I would like to get a complete kit for just a bit more than that.

so, Im assuming the S14 used a 228mm flywheel?