FS 3.07 LSD Sideloader

[JFENG]

"I actually think with the 4-speed the 3.07 would make sense to lower the revs in top gear. That said I wonder what happens in first."

Diff ratios are simple, if you go 10% taller, you lose 10% torque (relative, in any gear). Going from a 3.64 to a 3.07 will cost you nearly 20% in any gear. That's a lot as E9's aren't very fast cars in any gear in their original configuration.

My suggestion is to go with the tried and true combinations: These have proven out over time with thousands of enthusiasts and by the factory.

4spd with 3.91 - good for the track where it's rare you will spend much time at 120mph unless it's a real race car.

4spd (direct 4th) with 3.07 - good for highway cruising, but you'll definitely feel the loss of torque in 1st gear on a stock or near-stock motor. This was the standard setup for the early E-types sold in Europe. It's a great GT setup if you want to keep the 4spd. But, if you do things like mountain tours with steep hairpin turns, I'll bet you will end up 1 gear lower than you are accustom to. You might even find yourself using 1st gear in corners (if you've done the Mount Equinox hill climb you know what I mean). Good excuse to learn double clutch downshifts. If you've got a nice stage II 3.5liter B34 or B35 setup for low end torque, well that's a different situation.

5spd (OD 5th) with either the 3.64 or 3.45 (the latter having long legs if you do a lot of highway cruising in your classic car). Personally, the idea of cruising down the highway for a couple hours is not my idea of fun, but I am sympathetic for those of you who do things like drive from Laguna Beach to Monterey or Phoenix.

5spd (CR, direct 4th) with the 3.07: To me this is the sweet spot for people with big displacement motors. This was the setup BMW picked for the Euro 635Csi (which had slightly larger diameter tires). With a powerful enough motor, this might even be fun for HPDE events. Doesn't Duane Sword run this setup in his Alpina?

 

[Bill 74 3.0 CS]

"I actually think with the 4-speed the 3.07 would make sense to lower the revs in top gear. That said I wonder what happens in first."

Diff ratios are simple, if you go 10% taller, you lose 10% torque (relative, in any gear). Going from a 3.64 to a 3.07 will cost you nearly 20% in any gear. That's a lot as E9's aren't very fast cars in any gear in their original configuration.

My suggestion is to go with the tried and true combinations: These have proven out over time with thousands of enthusiasts and by the factory.

4spd with 3.91 - good for the track where it's rare you will spend much time at 120mph unless it's a real race car.

4spd (direct 4th) with 3.07 - good for highway cruising, but you'll definitely feel the loss of torque in 1st gear on a stock or near-stock motor. This was the standard setup for the early E-types sold in Europe. It's a great GT setup if you want to keep the 4spd. But, if you do things like mountain tours with steep hairpin turns, I'll bet you will end up 1 gear lower than you are accustom to. You might even find yourself using 1st gear in corners (if you've done the Mount Equinox hill climb you know what I mean). Good excuse to learn double clutch downshifts. If you've got a nice stage II 3.5liter B34 or B35 setup for low end torque, well that's a different situation.

5spd (OD 5th) with either the 3.64 or 3.45 (the latter having long legs if you do a lot of highway cruising in your classic car). Personally, the idea of cruising down the highway for a couple hours is not my idea of fun, but I am sympathetic for those of you who do things like drive from Laguna Beach to Monterey or Phoenix.

5spd (CR, direct 4th) with the 3.07: To me this is the sweet spot for people with big displacement motors. This was the setup BMW picked for the Euro 635Csi (which had slightly larger diameter tires). With a powerful enough motor, this might even be fun for HPDE events. Doesn't Duane Sword run this setup in his Alpina?

Thanks for all of the useful information. I won't be doing any mountain climbing, nor would I be spending all of my time on the freeways. And I definitely wont go on any tracks with it. I just want my car to be flexible enough for different enjoyment needs. Have good gas mileage out of it on the freeway, yet nice acceleration in 1st and 2nd gears. I have the original M30 engine with triple Weber carburetors, a mild cam, headers, and upgraded ignition.

 

[Stevehose]

I believe with my Getrag 265 and 3.64 diff I am doing 80mph at 3200rpm and 90 at 4k. With the 4 speed I was at 80mph and 4k.

 

[teahead]

http://www.csgnetwork.com/multirpmcalc.html

 

[aearch]

so where will i be with the s38 and 5 speed overdrive and the 3:91

 

[aearch]

thank you
so at 100 mph ill be running 4730RPM.
w/ 215 60 14.
right in the power band.
so much for gas

 

[Gransin]

so where will i be with the s38 5 speed overdrive and the 3:91

With 205/70r14 tires and if we're talking about the same five speed OD, Getrag 265, which have a final drive of 0.81:1, you'll be doing 80MPH @ 3365RPM

 

[Nicad]

When I was a kid I got a ride from Montreal to Mosport in a new 72' 3.0 CS 4 speed. I would think it had a 3.45 diff. We cruised for a length of time at 110 MPH. I wanted an E9 since that day and look forward to hearing it at high RPM on the highway. Thanks for the ride Mr Bowen.

 

[Bill 74 3.0 CS]

Getrag 265 OD, 3.45 diff, 3,000 RPM at 77 MPH. The sweet spot!

Don't you consider that to be a lot of rpm´s to run on a 40 plus year old engine? I take into consideration various things. Gas mileage, decibels inside the cabin, plus wear and tear on the engine. I would prefer to run lower rpms at the same speed.

 

[Bill 74 3.0 CS]

"I actually think with the 4-speed the 3.07 would make sense to lower the revs in top gear. That said I wonder what happens in first."

Diff ratios are simple, if you go 10% taller, you lose 10% torque (relative, in any gear). Going from a 3.64 to a 3.07 will cost you nearly 20% in any gear. That's a lot as E9's aren't very fast cars in any gear in their original configuration.

My suggestion is to go with the tried and true combinations: These have proven out over time with thousands of enthusiasts and by the factory.

4spd with 3.91 - good for the track where it's rare you will spend much time at 120mph unless it's a real race car.

4spd (direct 4th) with 3.07 - good for highway cruising, but you'll definitely feel the loss of torque in 1st gear on a stock or near-stock motor. This was the standard setup for the early E-types sold in Europe. It's a great GT setup if you want to keep the 4spd. But, if you do things like mountain tours with steep hairpin turns, I'll bet you will end up 1 gear lower than you are accustom to. You might even find yourself using 1st gear in corners (if you've done the Mount Equinox hill climb you know what I mean). Good excuse to learn double clutch downshifts. If you've got a nice stage II 3.5liter B34 or B35 setup for low end torque, well that's a different situation.

5spd (OD 5th) with either the 3.64 or 3.45 (the latter having long legs if you do a lot of highway cruising in your classic car). Personally, the idea of cruising down the highway for a couple hours is not my idea of fun, but I am sympathetic for those of you who do things like drive from Laguna Beach to Monterey or Phoenix.

5spd (CR, direct 4th) with the 3.07: To me this is the sweet spot for people with big displacement motors. This was the setup BMW picked for the Euro 635Csi (which had slightly larger diameter tires). With a powerful enough motor, this might even be fun for HPDE events. Doesn't Duane Sword run this setup in his Alpina?

I am simply trying to use a similar setup to what the engineers in Bavaria used on the E24 chassis. I know that car was heavier and bigger than the E9, plus it has higher output engines. I think that a good compromise would be a 3.25 final ratio in combination with the OD getrag 265. What are you thoughts?

 

[HB Chris]

Bill, 3000 rpm is the sweet spot on these motors, not loud but ready to respond at a moments notice.

 

[OCCoupe]

Bill I would rather be at the sweet spot versus loading up the motor by lugging the motor which will put a load on the crank bearings. I agree that 3,000 or so rpm is where the m30 is happiest.

 

[WISE9UY]

I am simply trying to use a similar setup to what the engineers in Bavaria used on the E24 chassis. I know that car was heavier and bigger than the E9, plus it has higher output engines. I think that a good compromise would be a 3.25 final ratio in combination with the OD getrag 265. What are you thoughts?

I tend to agree that 3.25 would be a good compromise for the high output engine. Refer to my thread at the following link for calculated speeds:
http://www.e9coupe.com/forum/thread...ar-for-different-gearboxes.23432/#post-172354

I will go out on a limb and say a well tuned engine does not need to be singing at 3000rpm to be responsive. Many moons ago my father had a 635csi with a 4-speed and 3.07 LSD and it was a very responsive and fast car. With and overdrive box you could certainly go to 3.25 but I do have concerns with the 3.64 being too tall. This all depends of course on the environment that the car will be used (motoway, track etc) and how it will be driven. Each to their own.

 

[Stevehose]

I'd say 3k rpm is the low end of the sweet spot which I think is 3-4k. Any lower in high gear and it will lug along.

 

[WISE9UY]

A good M30 can be left in direct drive and should slowly pick up from sub 1000rpm. At least this is how I know M30s and can certainly do that with my carburetted CS and remember that from the E24 and my E3. My view is that above 4000 without turbo, the absence of multivalve technology breathing leaves the M30 kind of slow in further uptake of revs at that point. At least that is why I am going force induction to liven things up from 4k.

 

[sfdon]

The factory BMW 745i turbo had maximum horsepower at 4900 rpm.
Maximum torque was at 2000 rpm through 4000 rpm
The earlier m102 turbo engine maxed out its torque at 4000 rpm
The 2002 turbo maxed its torque at 4000 rpm
It appears that none of these cars were helped above 4000 rpm by having a turbo.
My turbo BMW runs 22psi of boost and I never go past 5000 rpm.

 

[WISE9UY]

The factory BMW 745i turbo had maximum horsepower at 4900 rpm.
Maximum torque was at 2000 rpm through 4000 rpm
The earlier m102 turbo engine maxed out its torque at 4000 rpm
The 2002 turbo maxed its torque at 4000 rpm
It appears that none of these cars were helped above 4000 rpm by having a turbo.
My turbo BMW runs 22psi of boost and I never go past 5000 rpm.

I can only talk from experience and I am not doubting your numbers. My Callaway E24 absolutely roars away above 4k all the way to 6k. The 635csi my father had would go to 6700rpm but I recall from 5k it could have done with some help. Each to their own... I am not arguing my point, just stating my experience

 

[Bill 74 3.0 CS]

Bill I would rather be at the sweet spot versus loading up the motor by lugging the motor which will put a load on the crank bearings. I agree that 3,000 or so rpm is where the m30 is happiest.

Thanks for your input. I will keep that in mind. I will try to stick to something close to the actual final drive 3.45 that I currently have. Seeing that the 3.0 CSI version of our car got the 3.25 final drive ratio and has 200hp out of its M30 engine, and that I am running a bit more hp out of my engine, it would be the best choice, plus I'm running tires 225/45/17 at the moment, but thinking of going down to 205/50/17 once the car is fully restored.