Mark writes via LinkedIn:
You may remember I asked a question about the right winter car for my wife here in southern Oregon some time ago – she is happy now with her Subaru Forester, right in line with what the B&B said she should drive.
My current question has to do with my 2000 Mazda Miata. It has a hardtop, but is otherwise stock. Due to the arrival of my 1959 Rover P5 Sedan project car, the Miata has to live outside in the winter. I’ve put winter tires on it, but should I also man up and spend the money for a LSD rear end? It is an easy swap, but since I am confused after looking online about how much I would benefit in the snow from such an upgrade, I thought I’d ask for some advice. Should I spend the money on the Miata, or put a kicking sound system in the Rover?
Sajeev answers:
So you didn’t get a Pontiac Aztek like I suggested? That’s pretty tragic, for me. Sounds like you did just fine, even though my advice proves you get what you pay for. Sorry about that!
So here’s my second shot: according to this site your Miata has a Torsen limited-slip differential. Which, thanks to the Spec Miata racer scene, is a rather hot commodity. I asked my Spec Miata friend (and all around cool chick) about her experience with adding a Torsen to her car, and it sounds rather cost prohibitive: buying a used LSD (and then rebuilding it) is about $1300, from a reputable shop. Neither of us much care for this route in your situation.
Of course you don’t have to rebuild it, a used part might be adequate for non-racing purposes. And maybe finding one is easier and cheaper in Oregon. But still, a couple of sandbags in the trunk is a smarter pairing with your winter tires. The Rover will thank you for it.
Send your queries to mehta@ttac.com. Spare no details and ask for a speedy resolution if you’re in a hurry.
I would strongly recommend an LSD if the snow tires don’t cut it. After a winter in Texas where we had lots of snow and ice, my LSD equipped Explorer did very well out on the roads with just all-season tires. My peg-leg ’77 Chevelle didn’t do nearly as well, slipping and sliding and being generally disagreeable to any real forward motion. (Had to drive it to the parts store to get a new t-stat for the Explorer, it apparently would stick open)
In a short wheelbase vehicle limited slips in the snow and ice can be both good and bad. You have to know what you’re doing when driving in the winter, which you likely do. With my long wheelbase Cutlass Supreme sedan with a nice tight Posi-Trac and all season tires in the winter and 120lbs of sand bags in the trunk, I did alright as long as I was very conscious about road conditions and such.
Short wheelbase vehicles with limited slips are easier to make do a 180 on ice and snow, I was a subscriber to Four Wheel and Off-road magazine and a few of the readers and contributors wouldn’t let their wives drive their first gen Broncos and 1970s CJ Jeeps in the snow and ice because the Detroit Lockers they had in the rear made the vehicle too easy to rotate all the way around.
Good points about the short wheelbase issue. I drove my 2001 Miata (with LSD) through 5 Ontario winters, and usually wished it had an open diff.
The car would rotate very easily, and while that’s fun when you want it, it’s a handful in white-knuckle situations when you just want the damn car to track straight and stay out from underneath that truck trailer that’s passing you and overwhelming your tiny wipers with slush.
I have driven rwd in snow since day one, and always have 4 good snow tires. The Miata with LSD was just too twitchy for me on snowy days.
As for adding weight to help traction, this has been debated ad nauseum at miata.net
Good point about short vehicles, my Rav4 is generally fantastic in the worst of conditions but if it starts to spin, there isn’t time to do anything but hope for a soft landing.
A neighbor of mine had a AMC Gremlin with the V8 and a tight posi. You should have seen how he could spin that sucker in a Northwest Ohio winter! It wasn’t transportation it was an amusement park ride.
You don’t need to rebuild a used 94 and up Miata LSD. They’re Torsens, they don’t have any clutches. You can get the differential itself and swap it onto your existing housing for under a grand, sometimes hundreds less if you score a local deal or camp on miata.net and other forums. Only parts you need in addition to the diff are a couple of exhaust pipe gaskets and a quart of gear oil.
That being said, I drove my 97 Miata on all-seasons and an open differential through two central Ohio winters without a problem, and here in Washington on summer tires. Dorifto kingu.
My personal view — based on experience with two different cars — is that limited slips are useful on dry pavement but a very mixed blessing on snow and ice.
The basic problem is that, with a rear-wheel drive car, once both rear wheels are slipping, engine torque throws the rear of the car to the right. This is true even with cars that have traction control. On the few times that I have found myself involuntarily driving my Z3 in the the snow, I also found myself sometimes going uphill “crabwise” with the car pointed to the left, but going straight uphill, the rear wheels spinning slowly (limited by the traction control). You can limit — but not eliminate — this effect by counter-steering. (I’ve never had a car threaten to do a 180.) But, it may have the consequence of driving your back wheels off of the road . . . where you will get thoroughly stuck. I’ve never driven a Torsen LSD; to the extent that it does not deliver equal torque to both rear wheels, it may limit this slewing effect. And, I should add, the slower the car is moving forward, the greater this effect seems to be. That’s why it’s not much of a problem on dry pavement; a car spinning both rear wheels on dry pavement is also accelerating rapidly and moving forward very fast.
So, I would stick with investing in a set of true snow tires and perhaps a bag of sand in the trunk. The Miata has the virtue of being light . . . which makes it stop, turn and go better than you would think. However, it has the vice of having limited ground clearance, so it’s not an ideal snow vehicle.
The best thing is to get a set of *skinny* snow tires on base steelies for winter use (and replace the shocks if they’re still the originals). An LSD might be useful, but one problem with a Torsen is that both wheels have to have some traction for it to work. If one wheel goes into a full slip, then it acts just like a regular open diff. A clutch-type LSD would remedy that, but then you get into $$$ for install and setup of the clutch packs.
Based on my own old experience years ago with a rwd ’77 Corolla, my guess is that with snows on the back and some weight in the trunk you should do just fine. I did fine even without snows, but with the weight.
and stay away from that LSD. Some of the people I knew in the late ’60s and early ’70s had BAD TRIPS!!!
I agree with David. Out in that area I would suggest Plum Brandy.
Augustus (the Bear) Owsley died in an auto wreck in Australia not long ago.
He moved there to get away from the inanity of the USA.
Swapped a few e-mails with the hombre over the years; we used to live not all that far away from each other but never socialized; age and social differences but the guy was interesting.
Don’t think he ever owned a Miata.
If you think Australia is inanity free – you haven’t been here
You can get a Miata low mileage Torsen limited slip differential for much less than 1300 if you look around. A very wide range of model year’s diffs will swap in directly. Pretty much all 94-2005 use compatible differentials, which gives you a lot of options. Check with any local Miata clubs, they are everywhere.
I have 13 years experience driving a Miata in winter weather in MN and MI.
Winter tires and 70 lb bag of sand in the trunk are the only mods. Open diff.
The limiting factor has not been traction but ground clearance. In light fluff I can push snow that fills the grill opening. In heavier snow or esp. wind packed drifts once that car gets up on top of the snow you’re done-call a tow or get out the shovel.
On short runs momentum will get you through pretty nasty stuff but your steering skills better be ready.
Bunter
I’ve been driving RWD BMWs with no LSDs here in Colorado for over 30 years. I’d spend my money on extra rims and real winter tires.
I had a set of lower (higher numerical) gears and a posi-trak unit installed in my Crown Vic last year. The posi didn’t make that much difference driving in the snow this past winter. Unless you can get a rear swap / posi install done cheap, I would spend that money on a good set of dedicated snow tires and call it a day. If that doesn’t work out then throw a rear in next year.
Most of our automobiles had limited slips until we moved to the Carolinas. I think they helped. Two rear wheels spinning is a lot more exciting than just one. Unless you do a lot of drag racing, spend the money on tires.
Standard Torsens do funky things in the snow. I had a Mustang that went from a std clutch type diff to worn out clutch type to a Torsen T2 (non-R). The Torsen sends power to the rear irratically in very slippery conditions – aiming for whatever tire has zero traction. Torsens work great when both tires have some traction. They are crap when one tire has zero. R-model Torsens have some ‘pre-load’, correcting this. You’re better off with an open diff.
At first glance I thought “Murilee bought a Miata??”
Anyway he already said he’d put winter tires on the Miata.
I would have thought that proper winter tires and steelies would do it, but I’m not familiar with Torsen funkiness.
Both our Focus ZTS and our non-ABS 2007 Caravan went from terrifying deathtraps to snowmobiles by putting on proper snows.
/* Style Definitions */
table.MsoNormalTable
{mso-style-name:\"Table Normal\";
mso-tstyle-rowband-size:0;
mso-tstyle-colband-size:0;
mso-style-noshow:yes;
mso-style-priority:99;
mso-style-qformat:yes;
mso-style-parent:\"\";
mso-padding-alt:0in 5.4pt 0in 5.4pt;
mso-para-margin-top:0in;
mso-para-margin-right:0in;
mso-para-margin-bottom:10.0pt;
mso-para-margin-left:0in;
line-height:115%;
mso-pagination:widow-orphan;
font-size:11.0pt;
font-family:\"Calibri\",\"sans-serif\";
mso-ascii-font-family:Calibri;
mso-ascii-theme-font:minor-latin;
mso-fareast-font-family:\"Times New Roman\";
mso-fareast-theme-font:minor-fareast;
mso-hansi-font-family:Calibri;
mso-hansi-theme-font:minor-latin;}
My consultant on this Piston Slap wanted to share her thoughts in more detail, but cannot personally do that at work. So here they are:
*******
Sajeev is so sweet (tru dat. – SM) to include me, the “cool chick” mentioned above. Mark, here’s how I came to my conclusion: I own 2 Miata’s, a Spec Miata and a daily driver. I’ve owned my daily for five years, it’s my first Miata. It does not have a Torsen, but I spent many weekends at the track doing DE’s and time trials. I built my Spec Miata with a roll cage and a Torsen about three years ago. So I asked your question to the race shop that built my Spec Miata. They said, “you don’t need to waste your money and upgrade to a Torsen rear end in a daily driver, unless you are going to race it.”
That aside, I still get it: I grew up in Upper Michigan, where the white stuff gets so deep you either go on horseback or snowmobile to town . I did some ice racing too. Which brings me to my last observation: if you like to run WOT to see how awesome of an icy powerslide you can do on a snowy road, buy a Torsen. Otherwise you don’t need it in a Miata.
Oh, and about that picture, I’m thinking the red Miata looks like it has a Bull Dog bolt-in roll cage.
Wife’s NC Miata has a torsen, and it’s a handful in the snow, although it’s drivable in light-ish snow with stock (!!) tires if you take it easy and don’t try to go up/down a hill.
On my MR2, I have nothing but Blizzaks and an open rear end. The bottom of the hull is rather flat, so the car can traverse deeper snow than what its ride height would suggest. Of course, I don’t need no sandbags, I have my engine where it’s supposed to be.
Having driven many winters in many places in a couple of different miatas, I will agree with what most of the folks here are saying. Buy snow tires. I believe they still allow studs in eastern Oregon? do it. Also as said, the LSD is a mixed blessing, and traction will not be the problem, but rather the depth of snow. I’ll do 6+ inches of the light eastern oregon desert snow, but only 3 or 4 of wet concrete cascades snow. Once you high center you are done.
put weight in trunk will be cheaper way, I had a few Posi rear ends, is easier to spin out.
the posis are great when u need power to both wheels, but u going to meet the ice, and that will change it to an Amusement ride of Bumper car in a split sec.
As both wheels do lock, so u basically have no traction on slippery ice, and your rear end will not track straight! can u understand that?
Normal diff allow 1 wheel to turn along with the ice so u will atleast change direction when u want it, not unilaterally going whatever direction she likes.
It would have been a disaster if u had coughed up 1500 plus installation or u spend 6-8 hrs to crawl around like an Iguanna to have her installed, only to find out moments later thats not for u.
Get some good studless tires + 50 pounds of ballast in the trunk and have at it. I got around fine with 100 pounds of cement and Michelin Arctic Alpins on my 740 & 940 Volvos. Sure, they weren’t as good as having AWD but they got around fine in the snow of Eastern Washington state.
Of course I didn’t buy an Aztec, Sajeev – why buy a Prius look-alike if you don’t get the mileage?
Thanks much for the advice, everyone – especially those who own and drive Miatas. Looks like the Rover gets the project money instead.
I have winter tires for the Miata on a separate set of rims – studless snows, as the studs make too much noise. We can have studs here in Oregon, but the studless ones seem to work pretty well these days. Hereabouts we don’t get really deep snow most of the time, and those few days we do I can borrow the Forester if I need to.