Maximum Speed For Each Gear?

[JCtx]

Originally Posted by mkoesel

I thought it was the exact same transmission (cooler notwithstanding) that is in the 335i, and I'm almost positive that is a ZF.

Well, the conversation was about the DCT, and I read the info on the BMW site, so you can for sure read about that there if you want.

Since you're talking about a 335, you have to be talking about the manual. I also read several times about the manual being made by Getrag as well. Can't say for certain, but remember the poster was a respected member, so I believe that. I wish it was a ZF too, but doubt it. Maybe somebody can post a link to confirm or deny that. Take care.

[gr8000]

Originally Posted by mkoesel

You sure? I thought it was the exact same transmission (cooler notwithstanding) that is in the 335i, and I'm almost positive that is a ZF.

I am also positive I read somewhere (I will try to find the source) that the DCT is made by Getrag.

[gr8000]

Originally Posted by gr8000

I am also positive I read somewhere (I will try to find the source) that the DCT is made by Getrag.

Sources:
http://www.germancarzone.com/3-serie...hort-take.html

http://www.dctfacts.com/lnws_pg1a.asp

[mkoesel]

Originally Posted by elp_jc

Well, the conversation was about the DCT...

The original topic was about 6MT, and if you go back and read the exchange between PG and I carefully you'll see that it was the 6MT I was talking about.

Since you're talking about a 335, you have to be talking about the manual.

Actually no, since the 335i comes in DCT also outside North America and in fact uses the same transmission as the M3 in that case as well.

I also read several times about the manual being made by Getrag as well.
...
Maybe somebody can post a link to confirm or deny that.

These folks are convinced its a ZF:

http://www.e90post.com/forums/showthread.php?t=269041

PG must know for certain. PG, don't keep us in suspense. ZF or Getrag?

Originally Posted by gr8000

I am also positive I read somewhere (I will try to find the source) that the DCT is made by Getrag.

Thanks for looking it up, but I wasn't talking about DCT.

[southlight]

Originally Posted by PencilGeek

Ack, I couldn't find the pictures I thought I took. But I did find this from one of my pictures. This is a picture of a casting mark on my transmission (6MT). Clearly, the casting is "ZF."

The DCT is a Borg-Warner design, built by Getrag.

Completely right. You can also tell from the part codes. The 6MT is called "GS6-53BZ". The last z stands for ZF. To compare, the DCT is called "GS7D36SG" with the last g standing for Getrag.


Best regards,
south

[dimabimmer]

I get 70 mph in second gear, and 116 mph in third in my 335i 6mt...is it faster than M3?

[JCtx]

Originally Posted by PencilGeek

This is a picture of a casting mark on my transmission (6MT). Clearly, the casting is "ZF."

As I said, I wasn't positive about the 6MT being Getrag (just read about it), but it's clearly great news for us 6MT owners, as ZF is considered the best tranny maker (hope I'm not wrong on that now that you found it's a ZF ). My only question left is if ALL 6MT trannies are made by ZF. I'll make sure to check mine one of these days.

The DCT is a Borg-Warner design, built by Getrag.

I was positive about this one being Getrag from the BMW document, but didn't know it was a Borg-Warner design; interesting. And sorry I thought the discussion was about DCT. I wasn't about to read the whole damn thread to find out for sure .

Anyway, thanks for setting the record straight . Good day gang.

[mkoesel]

Originally Posted by dimabimmer

I get 70 mph in second gear, and 116 mph in third in my 335i 6mt...is it faster than M3?

The 335i has the same transmission gearing (same transmission) as the M3, but has a much lower final ratio (I don't know the exact numbers - you can look them up, but its something like 3.85 on the M3 vs. 3.17 on the 335i). This makes the 335i top speed theoretically higher. But in reality it will probably be around the same as the M3, or somewhat lower due to the suspension.

Originally Posted by elp_jc

As I said, I wasn't positive about the 6MT being Getrag...

Actually you initially said, "There're no ZF trannies on the M3. They're all made by Getrag.", but its no big deal - we all make mistakes.

[gr8000]

Originally Posted by lucid

Contact the admins directly via PM. "Jason" and "MarkE90M3", and/or post the issue in the site related questions forum below. Thanks.

http://www.m3post.com/forums/forumdisplay.php?f=8

P.S. We should make your info a sticky since it sounds like you have GPS validation. The only question is if the top speed you have in 6th (via GPS data) was drag limited before the car hit the redline? In other words, what rpm was the car at when it maxed out at 188 mph? Also, it would be good if you could reference the magazine that did the GPS validation. Thanks again.

I have contacted Jason, he immediately replied and asked me to send him an email with the attachment so that he could send me a link I could post. I did the email and after several follow on PMs no signs of him (probably too busy or something). I am not in a mood to keep bugging people so I will leave it to this - ok maybe I will send him a last PM now.

[southlight]

Originally Posted by mkoesel

The 335i has the same transmission gearing (same transmission) as the M3, but has a much lower final ratio (I don't know the exact numbers - you can look them up, but its something like 3.85 on the M3 vs. 3.17 on the 335i). This makes the 335i top speed theoretically higher. But in reality it will probably be around the same as the M3, or somewhat lower due to the suspension.

Top speed is similar for both cars. The M3 has a lower final drive ratio (3.85 vs 3.08), but also a higher redline and bigger wheels (about 10 cm more circumference).


Best regards,
south

[bruce.augenstein@comcast.]

Originally Posted by lucid

OK, so you are explicitly accounting for tire deformation. I get the tire diameter from Tirerack as opposed to using the generic formula since the published numbers are either directly measured by a vendor or supplied by the manufacturer (I suspect it is the latter in this case). I thought that measurement accounted for load, and it turns out it doesn't. It's for an inflated tire mounted on a test rim (9.5" in this case since I am looking at the BMW spec 265/35/19 PS2), but no load.

However, the "revolution per mile" spec is more interesting as it sounds like it is determined empirically. It's not clear if that is for a loaded tire, but if you just use the diameter info to calculate that yourself, you get a lower number of revolutions than what is indicated, suggesting that the revolutions per mile spec accounts for some kind loading/deformation. For instance for the 19" OEM PS2, diameter is 26.3", which should yield 767 rev/mile for an unloaded tire on the 9.5" test rim, but the published "rev/mile" spec is 790. If we use the published rev/mile spec of 790, that should account for most of the difference between your top speed number and the one PG and I have arrived at independently; 790 rev/mile corresponds to an effective rolling diameter of 25.53", and the 6MT gearing/readline limited top speed I calculated drops down to 190.4 mph from 196.1 mph.

Also, the load on the wheel must be somewhat related with vehicle speed, and if the rev/mile spec is indeed for a loaded wheel, it is not clear at what speed that is obtained.

Are you sure your zip file size does not exceed the max allowable file size for that file type?

While we're on moderately arcane data down here in the weeds, A Goodyear engineer told me that a good rule of thumb is to take the calculated revs per mile of a given tire, and divide the result by .965 to get a loaded revs per mile number.

On the same subject, a Michelin engineer told me that a good rule for them was to divide the unloaded tire diameter into 20,900 to get loaded revs per mile.

Anecdotally, calculating speeds in gears is a reasonable and worthwhile effort, but everyone (who hasn't thought about it) should be aware that you'll never get to those calculated speeds if you're chasing after it, because of tire slip under acceleration.

Bruce

[JCtx]

Originally Posted by mkoesel

Actually you initially said, "There're no ZF trannies on the M3. They're all made by Getrag.", but its no big deal - we all make mistakes.

You conveniently left out this:

'I also read several times about the manual being made by Getrag as well. Can't say for certain, but remember the poster was a respected member, so I believe that.'

I never take as fact something posted here, and neither should you . Signing off. Good day.

[lucid]

Originally Posted by bruce.augenstein@comcast.

While we're on moderately arcane data down here in the weeds, A Goodyear engineer told me that a good rule of thumb is to take the calculated revs per mile of a given tire, and divide the result by .965 to get a loaded revs per mile number.

Tirerack description for the revs/mile specs states the following:

"Depending on the tire manufacturer, revolutions per mile may be either measured in a laboratory or derived from a calculation based on previous test experience."

Which is still vague about the methodology. Do you know what type of "test" they might be referring to exactly? Is it for a loaded/mounted tire on a car at a specific steady speed for instance?

Originally Posted by bruce.augenstein@comcast.

Anecdotally, calculating speeds in gears is a reasonable and worthwhile effort, but everyone (who hasn't thought about it) should be aware that you'll never get to those calculated speeds if you're chasing after it, because of tire slip under acceleration.

Sure, if you are on the throttle, there will be slip. Have you seen any type of formal characterization of this effect on a straight line?

[footie]

Originally Posted by bruce.augenstein@comcast.

While we're on moderately arcane data down here in the weeds, A Goodyear engineer told me that a good rule of thumb is to take the calculated revs per mile of a given tire, and divide the result by .965 to get a loaded revs per mile number.

On the same subject, a Michelin engineer told me that a good rule for them was to divide the unloaded tire diameter into 20,900 to get loaded revs per mile.

Bruce

Both engineers are spot on.

But as all of this is theory and not actual I will watch how this thread develops.

P.S.

I seriously hope no one is using the rev counter to calculate the actual speed using this formula.

[mkoesel]

Originally Posted by southlight

Top speed is similar for both cars. The M3 has a lower final drive ratio (3.85 vs 3.08), but also a higher redline and bigger wheels (about 10 cm more circumference).

Good point south - I completely forgot to consider those, especially redline.

Originally Posted by elp_jc

You conveniently left out this:

Oh, well I was just talking about your initial response. No indication on your part of being unsure there. Like I said, though, no biggie.

I never take as fact something posted here, and neither should you

This forum is full of great facts - but yes I always double check with another source when I can. That's how I knew you were wrong.

[bruce.augenstein@comcast.]

Originally Posted by lucid

Tirerack description for the revs/mile specs states the following:

"Depending on the tire manufacturer, revolutions per mile may be either measured in a laboratory or derived from a calculation based on previous test experience."

Which is still vague about the methodology. Do you know what type of "test" they might be referring to exactly? Is it for a loaded/mounted tire on a car at a specific steady speed for instance?

Didn't get into that, sorry.

Originally Posted by lucid

Sure, if you are on the throttle, there will be slip. Have you seen any type of formal characterization of this effect on a straight line?

Saw some stuff from the SAE way back when we were working on a quarter-mile simulation, but it was info in regard to the effect of slip on coefficient of friction. Basically, max traction occurred in the 8 to 10 percent slip range on a street performance tire (around 10% better than initial slip), and began to fall away pretty rapidly after that - off a cliff at 20% slip and greater. For race tires (slicks), max came at around 35% slip, falling away more gradually as slip rates rose.

Never saw any torque/footprint/weight/cf vs slip stuff. Never looked for it in that precise way, though. You might try to check in with them.

[crypticc]

Originally Posted by bruce.augenstein@comcast.

Didn't get into that, sorry.



Saw some stuff from the SAE way back when we were working on a quarter-mile simulation, but it was info in regard to the effect of slip on coefficient of friction. Basically, max traction occurred in the 8 to 10 percent slip range on a street performance tire (around 10% better than initial slip), and began to fall away pretty rapidly after that - off a cliff at 20% slip and greater. For race tires (slicks), max came at around 35% slip, falling away more gradually as slip rates rose.

Never saw any torque/footprint/weight/cf vs slip stuff. Never looked for it in that precise way, though. You might try to check in with them.

Here... sliding friction once static friction is broken (or if lubricated by water) depends on the hysteresis (speed of recovery) of the tyre rubber in response to being deformed by the road surface. Interestingly the extra traction from a track tyre is due to pressure difference not softness of the rubber itself mechanically binding to the road as often thought.

high hysterisis rubber is slow to spring back from the road texture ... much like drag on a ship s hull in water is created by the water on the bow building up, and water on the trailing edge being slow to fill in the void. Tyre rubber creates a pressure difference either side of the lumps and bumps which literally drags on the tyre in the opposite direction to the slip as it slides over the irregularities. A soft tyre that moulds quickly and reforms once the bumps pass won't work as well as a harder tyre that allows the pressure to build before the bump and is slow to "rebound" once the deformation has passed


Excellent summary of the key forces here

http://insideracingtechnology.com/tirebkexerpt1.htm


They also explain why off the racing line works in the rain for the reason of the irregularities being less worn renaming this effect and not to do with rubber and oil as often cited.



Chris

[krx927]

since this resurfaced. Nice link to calculator:

http://www.m-forum.de/kalkulator/getriebe/index.html

[kb9uwu]

I wonder if the people in this thread even own their ///M3's anymore?!

[jphughan]

Originally Posted by krx927

since this resurfaced. Nice link to calculator:

http://www.m-forum.de/kalkulator/getriebe/index.html

Or one in English, with E9x M3 6MT values prepopulated: http://www.car-videos.net/tools/spee...B1=Recalculate