Question on gearing - did I do this right?

Ratio            % Change	Post Shift RPM
1st	3.6		        6000 <-- Assumed shift point
2nd	2.125     0.590277778	3542
3rd	1.458	  0.686117647	4117
4th	1.071	  0.734567901	4407
5th	0.829	  0.774042951	4644

These are the numbers for the 1984 Audi 4000 transmission. Later 016's only differ in the 5th gear going to 0.778 ratio. I've always been told "go with the 84, its a shorter ratio box" - ok, but not in the gears important to most situations...bottom line, I could use either without affecting overall results - only a few places I remember going into 5th anyway.

Final drive is 4.11:1

What I'm looking to figure out is where in the torque curve I end up given a gear and a shift point.

I noted last weekend, during a shakedown, that (I assume) due to the 34mm restrictor I was running out of torque past 6k or so RPM - shifting early (early to me) seemed to produce better results as I'd be back into the torque curve sooner.

Final Drive as I understand it will give me speed (assuming a tire diameter) vs. rpm - again, this might modify ultimately at which speed/gear I'd be in the best torque range. I do have an option to go to a 3.89 diff (hard to find), but lets start with the numbers above - then take it to a dyno and see where we stand.

Thanks,

Vittorio -

Depending on tire size, Here are some approx speeds at 6k rpm
1st 28mph
2nd 48mph
3rd 69mph
4th 95 mph
5th 120 mph

The 3.89 would bump your top speed per gear a little bit, but at a loss of torque. They are common enough the A4's came with a 3.89 or a 4.11 (open diff), the 200 10vt (and 5k) came with a 3.89 lockable, and the rare urq 3.89... but I dont understand why you would go to a longer final drive...

the 4k trans does have the shortest ratios of all the 016's
the 200 016s had the torsen center which would allow you to change your front rear bias.
Mega gear ratio thread: http://www.motorgeek.com/viewtopic.php?t=8293

I'm using the same trans, and have hear horror stories of using redline in it. I'll see If I can find the thread, it appeared to cause the same failure every time with redline being the common variant.

1 oh-ho & 1 dunno:

1. I recently loaded it w/Redline - I'd love to see the thread.

2. I thought the final drive was a multiplier, and assumed a lower number would give fewer revs per mph, thereby moving where in the torque curve you are relative to the average speed in a particular gear. So if on average a stage has 3's for turns, and lets say I can exit 3's @50mph, with the given gearing, I'd be outside of my torque range, on exit and not wanting to shift right there.

So I think its relative and really theoretical as I'm not going to change diffs and gearing ratio between events.

As for the 3.89 - I was thinking about it backwards.

Do I have the % change and resulting RPM after shift right?

Yes, a multiplier, as in miltiplies the input torque byxxxx The higher the ratio, the more torques at the wheel, at a cost of more RPM for a given road speed.

2 identical cars, one with the 3.89 the other with the 4.11, the 4.11 will accelerate quicker/have a lower terminal top speed.

Vittorio all gears are multipliers even a 1:1
I say best is to think of gears as a series of levers and the point the 2 teeth contact as the fulcrum.
Whatever the box ratio for each gear is, you're slowing speed by xx and multiplying torque by the same xx.

THEN you go to the last chance to do that: the final drive where you slow in down even more and multiply torque again by whatever the ratio is.

I know some idiot that is fixated with insane hp and torque and has for real 500 ft/lbs of torque
500ft/lb$ x 2.2 fir$t x 3.08 final drive =3388 ft/lbs to the back wheels in first
Sounds insane lots, si?

Whell a boring 8v 2300 Volvo turbo or Xratty with bare minimal fiddle can make 267 ft/lbs
267 ft/lbs x 2.95 first x 4.3 = 3388 ft/lbs to the rear wheels

---

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.

Quote
phlat65
Yes, a multiplier, as in miltiplies the input torque byxxxx The higher the ratio, the more torques at the wheel, at a cost of more RPM for a given road speed.

2 identical cars, one with the 3.89 the other with the 4.11, the 4.11 will accelerate quicker/have a lower terminal top speed.

Not so fast Sean!
Many many cars are geared sky high for MPG and EPA that they're effectively overgeared.

Just spoke with a nice guy out in Quebec yesterday who was saying that in the 16v VW with a 4.2 he couldn't pull max revs in 4th, much less think of even selecting 5th.

And those old V4s i fawk with would 'wheeze out' at 91mph, 140 km/hr with the typical tired V4 and stock 4.88 final drive, they go way past 105 with a 5.45 in the box.

So yeah the 4.11 car will be quicker AND may pick up some top speed.

---

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.

ok - I think this is all congealing in my brain (I figure solid is better than mush).

so in my case w/the 4k, if I generate a real 267ft/lbs of torque at the wheels x 3.6 first x 4.11 = 3951 ft/lbs with 4wd and I win!! si! but changing it to a 3.89 final I get 3739 ft/lbs, less - but I still win

I think I get it - but did I get the % change calculation right in the table - which will tell me where in the torque curve I land on each shift change? This should help me best use what I have once I get a torque curve - no?

http://www.motorgeek.com/viewtopic.php?f=15&t=39681&start=25

One of the threads I remember, couldn't find the other one. It appears the pin in the center diff likes to come out the wrong way, and some vague complaining about redline. However Scott doesn't recommend running it, and I assume he knows better than I

Thanks AJ - looks like another research project - what fluid to run in the 016. will be drained prior to next shakedown 12/30

I put in something made from dinosaurs and added some shockproof. We'll see what happens

Quote
vbares
ok - I think this is all congealing in my brain (I figure solid is better than mush).

Even semi-solid is better-er. Last 4 weeks my brain has been running down my throat into my lungs, and clogging my sinuses and I've been spitting and coughing up various colored hunks of my brain after they sit in my lungs and get all yummy.
I go to hospital next week for this, they're going to use a chisel and a long screwdriver (always use the right tools for the right job!) to rebuild inside my nose.

Quote

so in my case w/the 4k, if I generate a real 267ft/lbs of torque at the wheels x 3.6 first x 4.11 = 3951 ft/lbs with 4wd and I win!! si! but changing it to a 3.89 final I get 3739 ft/lbs, less - but I still win

Yeah but those 3739 toarks have to move 3739 LBS

Those nice rwd cars may have 3739 of those toarxz but maybe only 2600 LBS..

Quote

I think I get it - but did I get the % change calculation right in the table - which will tell me where in the torque curve I land on each shift change? This should help me best use what I have once I get a torque curve - no?

I dunno I just floor it till it begins to fall off and grab the next gear.
Your numbers throw me cause they only go to 6000, I always calculates at 1000 and 7000. And I'm zonked after pulling up 60 feet of chain link fence with weeds and blackberries growing thru it. I looked and said "YIKES!!!!! only 28 in first!!!!!"

I shoot for a min of 40mph in first 43-43 is fine too.

---

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.

Quote
JVL
Even semi-solid is better-er. Last 4 weeks my brain has been running down my throat into my lungs, and clogging my sinuses and I've been spitting and coughing up various colored hunks of my brain after they sit in my lungs and get all yummy.
I go to hospital next week for this, they're going to use a chisel and a long screwdriver (always use the right tools for the right job!) to rebuild inside my nose.

I like detail - perhaps, not that much though

Quote
JVL
Yeah but those 3739 toarks have to move 3739 LBS

Those nice rwd cars may have 3739 of those toarxz but maybe only 2600 LBS..

Tempt me all you want - I've got too much into this bitch to make a move - I've not properly flogged her and you know that just needs to be done.

Well - I've got 4 wheels a turnin (ok 3 mostly but who's counting)...

And I'll bet you make a comment about the RWD cars being close to 50/50 - well I've got 80/20 front to back

I'll get'er properly weighed so we can see how much she's dragging around...

Quote
JVL
"YIKES!!!!! only 28 in first!!!!!"

Trust me - we don't stay in first very long...

..and fer christ sake, get yerself fixed already...its not only with motors that CFM is all that but with the human body too...

Quote
john vanlandingham
I know some idiot that is fixated with insane hp and torque and has for real 500 ft/lbs of torque
500ft/lb$ x 2.2 fir$t x 3.08 final drive =3388 ft/lbs to the back wheels in first
Sounds insane lots, si?

Ooo, ooo, I want to play.

550 ft/lb$$ x 2.785 1st x 4.529 = 6937 ft/lbs to all wheels? (restrictors are for lawyers)

or

190 ft/lbs x 4.2 1st x 4.3 = 3431 ft/lbs to back wheels


Which brings up an interesting question - with gravel tires on your "average" road, how many torques can we actually put to the ground that aren't simply turned into tire dust? At CORE which is pretty slippery/dusty, I can get wheel spin when the motor comes on power (Vanos kicks in?) in 3rd gear...so:

190 ft/lbs x 1.66 3rd x 4.3 = 1356 ft/lbs at the back tires

Dave

Quote
DaveK

Quote
john vanlandingham
I know some idiot that is fixated with insane hp and torque and has for real 500 ft/lbs of torque
500ft/lb$ x 2.2 fir$t x 3.08 final drive =3388 ft/lbs to the back wheels in first
Sounds insane lots, si?

Ooo, ooo, I want to play.

550 ft/lb$$ x 2.785 1st x 4.529 = 6937 ft/lbs to all wheels? (restrictors are for lawyers)

or

190 ft/lbs x 4.2 1st x 4.3 = 3431 ft/lbs to back wheels


Which brings up an interesting question - with gravel tires on your "average" road, how many torques can we actually put to the ground that aren't simply turned into tire dust? At CORE which is pretty slippery/dusty, I can get wheel spin when the motor comes on power (Vanos kicks in?) in 3rd gear...so:

190 ft/lbs x 1.66 3rd x 4.3 = 1356 ft/lbs at the back tires

Dave

OK background so folks unnerstan this isn't my opinion, I am merely reporting what others with serious pedigree have all said.
VW farmed their rally engine development primarily to a guy straight South of Stockholm 40km in Södertälje, Sweden named Gunnar Forssberg from about 71-72.

Opel farmed rally engine and trans to a Norwegian guy in the Eastern suburbs of Stockholm named Janne Carneborn who runs Enem (like ''N'', ''M'' spelt out from ''Nacka Motorrenovering''.)

Saab ran their own rally department from 1959 to end of season 1980 and one of the engine development guys I've known since 1986 is named Bengt-Erik Ström who ran his own place on the side part time till end of 80 and full time after that including testing jigging and fixturing and some ''fine polishing' on some development stuff for Saab.

They all know each other (in fact it was Ström who put me in toch with Forssberg back in 93 when we began building the saab 16v n.a thing that went on to win Gp2 National title (back when there was more than 1 person towing to more than 2 events to win a title) in 1995.

All 3 at various times said ''Njääääääää, 220 maybe 230 bhp is plenty, after that work on delivery (power band and spread).

To my question ''But, but, but! You're making 265-270 bhp motors for the baddest 2.0 cars!!!''

All shot back same words ''Yeah? Who's buying your tires?''

That help?

---

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, I thought I had my tranny ratios figured out, but looking at this thread I seem to be lacking in the torque department.

I figure I can get 210 ft lbs out of my stroker Opel engine, with a 2.16 1st gear ratio (Tran-X) and a 5.29 Toyolet rear axle ratio. Works out to 'only' 2399 ft lbs in 1st gear, which seems to pale in comparison to others here. Should I be worried?

My car has to weigh 2271 lbs per the Group 2 rules...I will have to add ballast to get to that number.