What was the option list like for 1989 Carrera 3.2 Coupes? How much will I miss LSD?

[david c.]

"Well, in hard cornering the load on the inside rear is reduced, which reduces traction, which could result in the inside rear spinning under throttle and losing traction altogether. If the inside rear wheel spins, it has no traction, which increases the load carried on the outside rear wheel. If that increased load exceeds the outside rear wheel's available traction, then you either get oversteer or a spin, both bad."

If the above is accurate, my understanding of an open differential is totally wrong.

I've autocrossed my 915-equipped car many times and induced the exact type in inside rear wheel spin we're discussing. What seems to happen is that the car just slows down, no oversteer occurs, and it simply won't accelerate until it flattens out again and puts (some) weight on both rear wheels. This jives with my understanding of the function of an open diff in that the amount of power that is transmitted to the wheel with the weight is limited by the amount available to the slipping wheel.

[mmm]

Originally posted by dave cardone
"Well, in hard cornering the load on the inside rear is reduced, which reduces traction, which could result in the inside rear spinning under throttle and losing traction altogether. If the inside rear wheel spins, it has no traction, which increases the load carried on the outside rear wheel. If that increased load exceeds the outside rear wheel's available traction, then you either get oversteer or a spin, both bad."

If the above is accurate, my understanding of an open differential is totally wrong.

I've autocrossed my 915-equipped car many times and induced the exact type in inside rear wheel spin we're discussing. What seems to happen is that the car just slows down, no oversteer occurs, and it simply won't accelerate until it flattens out again and puts (some) weight on both rear wheels. This jives with my understanding of the function of an open diff in that the amount of power that is transmitted to the wheel with the weight is limited by the amount available to the slipping wheel.

Well I'm no expert on this, but so long as the traction load LOST at the spinning inside wheel, and resulting additional lateral LOAD transfered to the outside wheel does not exceed the outside wheel's available traction (which it may not loaded up as the outside wheel is in a corner), than everything would go just as you've said I think. BUT if the additional lateral load transferred to the outside wheel when the inside one spins IS enough to exceed the outside wheel's available traction, then I would expect oversteer at best and quite possibly a spin at worst.

It all depends on how much traction that outside wheel has in reserve when taking on the additional lateral tractive load from the traction compromised spinning inside wheel.

Now then, someone who REALLY knows this stuff should step in and correct me where I'm wrong.

An open differential essentially sends power to the path of least resistance. The wheel that has the least traction gets the most power. You can see this when trying to start out in slippery conditions. Often one wheel will just spin while the other one sits there and does nothing because the spinning wheel, with no traction, gets all the power given the open differential. A limited slip addresses this by limiting the distribution of power more equally even if one wheel has much less traction or spins.

[david c.]

That's my point. There is no increase in the amount of power added to the outside wheel under such circumstances because the path of least resistance, as you said, is the spinning inside wheel. Hence, no oversteer is induced. I've never, ever felt like I induced oversteer in my car but accelerating hard and spinning the inside rear wheel out of corner. If anything, it's a feeling of a lot of push and waiting forever for the car to settle and resume putting down power.

I don't believe an open differential ever lends itself to oversteer or a spin under either street drivng or autocross circumstance (the only ones I know). I wish sometimes my car did exhibit more power-on oversteer. This is certainly not always a bad thing.

[speeder]

Originally posted by dave cardone
That's my point. There is no increase in the amount of power added to the outside wheel under such circumstances because the path of least resistance, as you said, is the spinning inside wheel. Hence, no oversteer is induced. I've never, ever felt like I induced oversteer in my car but accelerating hard and spinning the inside rear wheel out of corner. If anything, it's a feeling of a lot of push and waiting forever for the car to settle and resume putting down power.

I don't believe an open differential ever lends itself to oversteer or a spin under either street drivng or autocross circumstance (the only ones I know). I wish sometimes my car did exhibit more power-on oversteer. This is certainly not always a bad thing.

Dave, Unless I'm missing something you seem to have it backwards. 911s, (especially in stock form), suffer from trailing throttle oversteer, not "power-on oversteer". Throttle steering a 911 requires being able to put the power to the rear wheels to counter oversteer, and if the available traction isn't there due to one wheel being unweighted and spinning, it's time to use your rear view mirror to see WTF you are going, as the old Porsche joke goes.

As I said before, I've had both and the factory 40% ltd. slip is worlds better. And it is not a system designed for starting out on slippery hills, for the last time!! Any rear engined/rear drive vehicle will "hook up" in that situation, that is not the issue.

With 245s on the rear and ltd. slip, my car is amazing in the canyons or at the track. I can absolutely point it in hard cornering using the loud pedal, which is much more difficult if you have lost 75% of your traction w/o LSD.

I've been on some "fun runs" w/ large groups of 911 owners, and the fact of the matter is that a substantial percentage of owners never drive their cars anywhere near the car's limits even in a deserted canyon, so these guys will not notice the presence or absence of ltd. slip. These are the guys who refer to Jack Olsen and Tyson as "CRAZY". Not that they aren't, of course.

Lastly, all of my comments apply to factory 40% ltd. slip only, aftermarket diffs w/ more agressive lock-up for track use can and will have severe downsides on the street, like your car "pushing" when you try to parallel park.

[david c.]

No, I gotcha. I was responding to what MMM wrote with regard to a car with an open diff: "If that increased load exceeds the outside rear wheel's available traction, then you either get oversteer or a spin, both bad"

I agree exactly with you but, the trailing throttle oversteer is not what he was discussing. And you said "suffer"! I like a little power on oversteer at times on a tight autocross circuit. That's why I have a 22mm rear ARB on my little 912E!

[mmm]

Originally posted by dave cardone
That's my point. There is no increase in the amount of power added to the outside wheel under such circumstances because the path of least resistance, as you said, is the spinning inside wheel. Hence, no oversteer is induced. I've never, ever felt like I induced oversteer in my car but accelerating hard and spinning the inside rear wheel out of corner. If anything, it's a feeling of a lot of push and waiting forever for the car to settle and resume putting down power.

I don't believe an open differential ever lends itself to oversteer or a spin under either street drivng or autocross circumstance (the only ones I know). I wish sometimes my car did exhibit more power-on oversteer. This is certainly not always a bad thing.

Yes, but say you're cornering, and while doing so the inside rear wheel is carrying 30% of the total rear lateral cornering load (because it's unloaded due to weight transfer in the corner), and the outside rear wheel is carrying the remaining 70% of the total rear lateral cornering load (again due to weight transfer). Now then, in carrying 70% of the total rear cornering loads, let's just say that the circumstances of this corner are such that the outside rear wheel is using 90% of it's available traction. In those circumstances, if the inside rear tire spins under throttle and thus losses much of it's traction, including lateral traction, the lateral loads it was carrying to hold the rear in line through the corner are largely transferred to the outside rear tire, increasing it's load and potentially exceeding its available traction. At that point the outside rear slips and you've got either oversteer or a spin coming.

[david c.]

If/when this happens, it's due to inertia, not because the outside wheel is spinning. But I see what you're saying. Of course, when you're spinning in that fashion, all four wheels are likely to be on the ground. I've never seen a car spin out at an autocross on two wheels.

[Russ in VA]

This thread is making me think ... I am confident that in power on situations a car with LSD is easier to spin because it forces the tire that is carring most of the corning load to take the brunt of the acceleration load as well (just drive a car with a torsen type LSD in the snow and you'll know what I mean ... or go try and do donuts in a car with no LSD, it's not nearly as much fun as doing them in one with a LSD) .... I am not so confident in predicting what effect a LSD has in a trailing throttle oversteer situation ... where are the suspension engineers ... I want to hear and educated discussion on this! My head hurts now...

[kevjandon]

I on my 4th 911. I've had a 70, 79, 90 and now an 83.

My 83 is the first with a factory LSD or any LSD for that matter. I'm a spirited driver and haven't had a chance to do a drivers ed yet, but there is something about that LSD that I feel makes the car better. Maybe it's all in my head, but the rear end just seems much happier with it.

I don't think I'll buy another 911 w/0 LSD.

[fastpat]

Originally posted by mmm
Heh. Nah, I'm looking for the "real" answer. I *THINK* it's probably not that big a deal for just street driving, but wanted to get a good read on it from folks here. Of course, it CAN be an issue in terms of putting the power down in low traction situations from a stop or at slow speeds too. Starting in the rain on a steep hill for example, where an open differential will be much more prone to just spinning one side....

My Carrera doesn't have limited slip and I probably won't install one. With the engine weight on the rear axle, I'm not likely to see loss of traction often. On my front engined, rear wheel drive BMW's I've installed or am installing limited slip diffs in all of them, but those cars can lose driven wheel traction much more easily.

[Wil Ferch]

Short answer is that the lack of LSD..in your circumstance....shouldn't be a factor to consider / not consider an otherwise fine car....

I have an 85 with LSD and feel that the rear is "planted" better...either power "on" or "off ...but I get this added sensation only when I'm deep into the performance envelope of the car....on the track.

Heck...with only limited track experience...I'm tempted to say that it may feel the same way w/o LSD...but I've driven similar cars on the track w/o...and there is a subtle difference.

More noticable...perhaps..is aggressive street driving during on-ramps maneuvers....especially if throttle is applied abruptly on /off. Better to be smooth.....

Wil

[mike sampsel]

For those interested in Z50 option group. My sticker has Z50 and it’s a $2,985 charge. So it’s difficult to believe the Z50 option corresponds to the one in this thread. I know I have 16” Fuch wheels on my ‘78 Targa. There is no list of these on the sticker, maybe they were part of the Z50 option in ‘78?

[ab1752]

I have 2 "toy" cars, an 89 Carrera without LSD and a 240Z that has a CLSD out of an 88 300ZX turbo matched to a 5 speed out of an 83 280zx. I think the argument of how a LSD affects overall performance for the OP is similar to my experience. In the 911 I don't notice not having LSD at all since there is so much weight over the rear tires and for highway carving and city usage that I use my 911 for I don't miss LSD at all. For the 240Z I definitely noticed a big improvement while the car is being used in the same manner as the 911 since it is very tail happy, now it is nicely planted.

For track or autocross I could see definite benefit of LSD for sure but I also find that it would be pretty hard for me to push my 911 that hard, to me anyway. I am a real fan of spending money on cars and have thought about adding LSD to the 911 but in my case, I can't see the overall benefits unless I needed to open up the gear box.

Awesome car, I like it a lot and really enjoy going between both cars.

[GH85Carrera]

Originally Posted by ab1752

I have 2 "toy" cars, an 89 Carrera without LSD and a 240Z that has a CLSD out of an 88 300ZX turbo matched to a 5 speed out of an 83 280zx. I think the argument of how a LSD affects overall performance for the OP is similar to my experience. In the 911 I don't notice not having LSD at all since there is so much weight over the rear tires and for highway carving and city usage that I use my 911 for I don't miss LSD at all. For the 240Z I definitely noticed a big improvement while the car is being used in the same manner as the 911 since it is very tail happy, now it is nicely planted.

For track or autocross I could see definite benefit of LSD for sure but I also find that it would be pretty hard for me to push my 911 that hard, to me anyway. I am a real fan of spending money on cars and have thought about adding LSD to the 911 but in my case, I can't see the overall benefits unless I needed to open up the gear box.

Awesome car, I like it a lot and really enjoy going between both cars.

Yea, good summary.

My 85 911 has an open diff. I have done over 100 autocrosses, and only in very tight corners did I ever get tire spin. For the street, it is just not an issue unless you are driving like an idiot. In twisty mountain roads you would have to be pushing stupid hard to have an issue.

My daily driver is my 1986 El Camino. Totally different driving experience. It came with an open diff. One day driving home in an ice storm I could just barely get moving, it was horrible. I put in a limited slip or posi traction rear end. Now in the bad weather I can get rolling much better. BUT and it is a big but, it takes real finesse and driving knowledge to drive in the rain or icy conditions with a limited slip. Making a turn and giving it more gas is done with great caution, the rear will come around in easily. If I am making a sharp right turn at a stop sign and give it much gas it will spin in a heartbeat.

This is a really old thread, and the OP likely is not a part of Pelican anymore.

Originally Posted by mmm

Car I'm looking at doesn't have LSD. How much will I miss that?

It does have:
Full Leather
Rear Wiper
AM/FM Cassette
Short Shifter
Sport Suspension
Power Windows
Power Sunroof
Power Seats
Power Locks
Headlight Washers
Front Air Dam/Spoiler
Rear spoiler
Cruise Control
A/C
Factory Alarm

So what is it missing in terms of the 1989 option list besides LSD?

I imagine that the stereo is not the top line option. What else was available and what else is it missing?

For street driving, I don't think you'll miss the LSD at all. I've had it on all my track cars, but my street 1985 does not have it, and I don't have any plan to install it. It's a nice-to-have option for bragging rights and resale, but will have limited use in normal street driving. LSDs tend to make the car push (understeer) because both rear wheels are in lockstep--it removes the "differential effect" that allows the car to turn easily. On track, the main benefit to me was under heavy braking, on corner entry, where the LSD adds stability by "squaring the car up." It also helps, of course, pur the power down on corner exit, but the stability under braking was the most important part for me.

If you really think you want it, you can always add a limited slip or torque-biasing diff pretty easily. The factory ZF units tend to wear out their clutches, so many cars originally equipped with LSD 30 years ago may not be getting much limited slip effect. You can tell by jacking the rear wheels, having someone hold one still, and checking the amount of breakaway torque required to move the opposite wheel.

I see you are local--welcome to the slippery slope!

[Matt Monson]

Damn. 15 year old off topic bump. Someone must have gotten some of the brien acid.

[ab1752]

Originally Posted by Matt Monson

Damn. 15 year old off topic bump. Someone must have gotten some of the brien acid.

Hahaha....nice. So the question for the OP is did he in fact miss LSD on his '89 or what?

[danco_]

Now you guys have me wondering. WHat is the path of least resistance for getting an LSD into my car? G50 trans. I have read up quite a lot on the factory option, the motorsport option, the Guards aftermarket option, the WaveTrac option, and one other that is escaping me at this time.

I am one of those canyon bomber types and in theory, a clutch type makes the most sense for me. But $3k for a Guards unit plus another $1000-1500 to install/calibrate puts this particular upgrade at a hefty cost.

For those of us ready to make terrible financial decisions, where can we find a reasonable stock unit or something that doesn't cost $4k?

[da Vinci Dan]

You will miss LSD at the vary moment your rear lifts mid turn and you go ass backwards into a ditch.

Wet roads, icy spots, slick tires, accident avoidance maneuver ... can all cause this, not just overly spirited driving.