E30 Zone

Who has had both?

Are the Sport gearboxes really that much better?

What is a Sport gearbox like at track days?

What is the right diff ratio for a Sport gearbox? 3.25?

Thanks!

3.91 is gonna be the one for track days..

Sport box will be better out of low speed corners.. its difficult tho, different circuits will suit different ratio boxes hence why proper race cars have adjustable ratio boxes..

I've driven a std 325 and its nice but the sport is more urgent. I think the diff is uber low at 3.91. Whats nice is that the interim gears are closed up - shifting from 4th to 5th is no longer a killer during accelerative bursts. All it needs is a sixth ratio to prolong the fun

It's pretty much optimal so long as cruising economy isn't an issue (if so go buy a derv drinking mundano or something).

I have a 3.91 for my standard non-Sport gearbox --- should I run a lower ratio for a Sport gearbox? Like a 3.25? Or a 3.73?

I'm not going to change the diff just for track days --- and I will have to spend some time on the motorways, etc --- so help me pick a good flexible ratio!

Thanks,

DieselMeister wrote:shifting from 4th to 5th is no longer a killer during accelerative bursts.

4th and 5th ratios are the same in sport / non sport boxes

3.91 is fine on the motorway

3.25 is waaay to long

BMW_YARD wrote:

DieselMeister wrote:shifting from 4th to 5th is no longer a killer during accelerative bursts.

4th and 5th ratios are the same in sport / non sport boxes

I thought the non-Sport 'boxes have an overdriven 5th gear, while the Sport 'boxes have a 1:1 5th gear?

Here are the ratios I have found --- are these correct?

Gear Ratios / Gear
Standard Close Ratio
3.83 3.72
2.20 2.40
1.40 1.77
1.00 1.26
0.81 1.00

sport boxes have the same 4th and 5th gear as the non sport

5th is 0.81 or summat..

e36 boxes are 1:1

This may be but the sport box plus 3.91 diff makes for a different driving experience imo.

I'd like 24 valves to go with that gearing to make even more of it

Jhonno wrote:sport boxes have the same 4th and 5th gear as the non sport

5th is 0.81 or summat..

e36 boxes are 1:1

As I understand it, and maybe I'm wrong, there are:

- Standard 5-speeds w/ overdriven 5th gear (0.81:1)
- Close Ratio 5-speeds, "Sport" 'boxes, all 5 gears are slightly higher than the gears in a Standard 'box, and a direct 5th gear (1:1)
- Dogleg CR 5-speeds, same ratios as Sport 'boxes

Where can I find the accurate info?

DieselMeister wrote:This may be but the sport box plus 3.91 diff makes for a different driving experience imo.

I'd like 24 valves to go with that gearing to make even more of it

What is your RPM / engine speed when you're doing 70mph w/ your 3.91 and Sport 'box?

It's a bit confusing having these two threads on about the same thing but this should help, it's taken from the owners manual

Fantastic!

Thank you -- that's what I needed!

80mph equates to around 3.5k rpm. A bit busy for a 2.5 litre but as its a bimmer straight six, it doesn't mind and sounds / goes absolutely fine.

Wind noise is the biggest problem for E30s, being shaped like the proverbial housebrick.

whats the top speed for a sport? mine struggles to even show 140 on the clock thats with 17s fitted so not sure if will make much of difference
were as ive been in normal 325i that seems to pull past that no bother

140 in a 325??? pull past that no bother??? sorry mate but dont think thats quite right. The factory quoted speed was only 135(actually 137) and those figures are normally optimistic, was your speedo in km/h??

Ive hit between 135 and 140 mph on the clock on 15's. How accurate my speedo is I dont know.

135 is about right, I have had 7 "Sports" that was the average

you speedo will be about 7-10% out so an indicated 140 will be a more realistic 125-130. and the size of your rims (within reason) will not make a great deal of difference if your tyres have the correct aspect ratio. and of course it will depend on road conditions i.e the gradient, a 5-10mph head wind will take a great deal of top end speed off of a car as un-areodynamic as an E30. and if is hot then you can forget another couple of mph. even my Z3 coupe with the M54 3.0 engine struggles to make 230km/h in summer, but... my 1000cc mini (slightly modded)would reach all the way round to the IGN mark on the speedo down the southbound M6 hill near the Tickled Trout which by scale is about 105-110 mph!

Dav not saying you didn't see this speed but were the two road conditions the same? so many factors affect top end speed.

mrlee

sport box is better imo. but i would only use 3.64, 3.73 or 3.91 diffs whichever u prefer. 373 is the best of both worlds

For a track car, which diff would you choose? A 3.91?

if it's a track car for using on UK's circuts i'd use 3.91 yes. All our tracks are short really and it will give the best acceleration.

i found 3.91 to fine round the ring also

Another vote for Sport gearbox.

Big difference when going from 2nd -3rd gear.

Sal

well as i said it was only indicated on my speedo and i knew that isnt accurate.the road was the same long stretch of road.obv not excact same conditions as wasnt the same day but felt the normal 325i had a much better 5th gear maybe it was he had a standard exhaust and my one makes some noise at that speed .maybe just made it feel like the car wasnt trying as hard i dunno

forgot to add this road was in germany

dav325i wrote:well as i said it was only indicated on my speedo and i knew that isnt accurate.the road was the same long stretch of road.obv not excact same conditions as wasnt the same day but felt the normal 325i had a much better 5th gear maybe it was he had a standard exhaust and my one makes some noise at that speed .maybe just made it feel like the car wasnt trying as hard i dunno

The reason people do not believe you is because they do not know what can be achieved with changing ratio's of gearbox's and diff's.

With a 2.0L gearbox and a 3.25 LSD, my car did 130mph (Speedo reading) in 4th at 6000rpm!
She was doing 140mph in 5th at about 5500rpm!

The ratio's may have been changed mate, you never know

I changed the ratio of my diff on mine to 3.64, does about 130-135mph in 5th now LOL