Diff ratio for R200

SeanDezart

SeanDezart

Well-Known Forum User
Doesn't really matter does it, the fun of dropping two gears quite unnecessarily whilst alongside Mr 911 and waving bye-bye doesn't leave much time to glance at the speedo :)
 
Mr.G

Mr.G

Club Member
Mike please chime in.

Can you give us your drag racing experience as to what diffs are best to use. Did you get a lot of wheel spin in 1st gear with a 3.9 was there much imporevement with a 3.54?
 
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Wyn

Wyn

Club Member
Like a bus these things
Wait for one .... then 2 turn up :D

Another with the same ratio, but the other numbers vary :confused:
39.11B C52.01D 18B5 - +6


r2003.jpg


Maybe the next one I find might have a slippa aswell
pray.gif
 
S

SKiddell

Well-Known Forum User
Did you get a lot of wheel spin in 1st gear with a 3.9
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Mike is definitely the man to answer this but

I can give you some slow 13.7 second experiance (using a 3.9)
IMHO It is unrealistic to expect on a modestly powered and light weight car (200+ rearwheel Hp) that dumping the clutch will have any effect other than spinning the wheels or tramping your back end all over the shop so progressive feeding of the clutch is required, if you experiance wheelspin, work on the technique rather than swap your diff out, its easier.

Further more, the larger your diff ratio (4.37 etc) - the more gear changes you may experiance in running a quarter

For example a 4.11 @ 7000 rpm gives 96 mph in third, crossing the line at this wont give you a world beating time
Reving to 7500 gives you 104 MPH in third which could put you into the 13's (if the power is there:D )

I experimented several times changing up to fourth and it cost me couple of tenths every time.

Just my 2 pence worth
 
Black Bug

Black Bug

Well-Known Forum User
Using Albrechts extremes (3.154:1 and 5.143:1) and my cunning car speediness simulator (CarTest2000) with a very generic 240Z, I found that over a 1/4mile there was a difference of just 0.4s and for 0-60 there was a difference of 0.57s, the 5.143:1 was the quickest on both, but not by a staggering amount. I'm not bothering to post the actual times as I think just looking at the comparison data is more appropriate.

The fun thing with CarTest2000 is it tells you how to get the best start, clutch dump or slip, and tells you the best rpm to start at, for the 5.143:1 it recommended a clutch dump at 2400rpm, but for the 3.154:1 it wanted to fry the clutch at 6300rpm.

Upshot is, if you want to go faster, get more power!!

Cheers,
Rob
 
Legendary5

Legendary5

Well-Known Forum User
If you want to swap diff’s you read sometimes about the Ring Gear. You’ve got ring gears with M10 bolds and M12. Don’t have a clou what they mean and where the ring gear is located??? Who can help..
 
Black Bug

Black Bug

Well-Known Forum User
Legendary5 said:
If you want to swap diff’s you read sometimes about the Ring Gear. You’ve got ring gears with M10 bolds and M12. Don’t have a clou what they mean and where the ring gear is located??? Who can help..
Click to expand...

Ring gear is just American for Crown wheel if that's of any use. Look at Wyn's pic in post #43, the ring/crown is the large coggy bit on the left with 18 written on it.

The M10 or M12 bolts are used to hold the crown to the diff centre. On the earliest R200s they used M10, then changed up to M12 at some point. It should also be noted that the viscous LSd centres found in a lot of modern R200s use M13 (I know, mad size) bolts.

Hope that helps a bit.

Cheers,
Rob
 
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