Needing to Make a Miata More Understeery

Hello All,

I am in need of a quick bit of advice. I am going to be loaning my 1991 Miata to a friend for a few months and since he has very limited experience with RWD cars I wanted to make the car a bit less likely to oversteer on him if he hits the limit.

As it stands now, I have the adjustable FM anti-sway bars front and rear, but stock suspension. My alignment is set-up to be neutral while neutral throttle, but if you lift off at the limit the rear end will come around.

I would like to do something quick and easily reversible to keep the rear end more planted under throttle lift situations. Understeer is favourable to me right now.

My initial thoughts are to soften or disconnect the rear sway bar entirely, but I wanted to consult with the knowledgebase here before I condemn this man to spinning my car into a guardrail.

Any help is appreciated!

Thanks, Martin

Disconnect rear sway bar.

Or.... tell him if he wrecks it, he buys it, and maybe he won't drive it at or beyond the limit.

Not to sound like "that guy", but...

If he's going to be driving your car on the street anywhere approaching the limits of traction, and he doesn't have the fear and good sense to understand what happens at or near those limits, why the hell would you lend a car to him???

editSFO beat me to it

On topic, could you disconnect or remove the rear sway?

Front bar full stiff and rear bar full soft (or disconnect like mentioned). A step further would be to adjust the front toe inwards to induce more understeer.

Put skinny tires on the front?

Cone_Junkie wrote: Front bar full stiff and rear bar full soft.

This.

Or tell him something along the lines of "Hey Friend, dont wreck my car."

Put stock rear bar back on, adjust tire psi.

if this is a concern just start planning and budgeting for an exocet now

Just take the rear bar off completely and store it until you get the car back.

There's room for making the car more user-friendly for an inexperienced driver, and disconnecting the rear sway is probably all you need. IMHO the 5/8" FM rear bar is way too aggressive in any case.

It's 2 nuts to disconnect it, and then a few zip ties to stop the end links from flapping around. Easy peesy, do that, then take it out and do a throttle-lift-while-cornering yourself in a safe place and see what it does. With the FM front bar and no rear it should be very understeery.

I was always told that the rule of thumb is "The stiffer side slides". Obviously that isn't always the case, as other things factor, but with all else being equal, removing the rear bar should make the car more prone to understeer.

adjust tire pressures; more in the front and less in the rear is my recommendation.

Hi, thanks so much for the replies and info! I suppose a bit more background is needed: My friend is probably the most responsible person I know, and I have zero concerns about him pushing the limits. I just know that my car is twitchy at the limits, and I want to minimise any surprises if he encounters something unexpected like gravel in a corner or stopped cars at the end of a cloverleaf on-ramp, etc.

He will have the car for about 5 months (long story, but he needs a loaner until he leaves the country), so I was looking for something simple that doesn't require specific maintenance (such as differing tire pressures). I think I will just disconnect one end of the rear bar and zip-tie the link.

Thanks again for all the input, I am happy to know I was on the right track. Insurance will cover him if it gets wrecked (we have this arranged already), but honestly, 99.99% chance that it would be caused by someone else if he does get in a collision.

I'm with Codrus. Just disconnect the end links and tie up the rear bar. Two bolts.

Add V8, stir.

I like the term understeery and it sounds like your friend is lucky to have you as a friend.

Toe in front and back. No performance for you!

DavidinDurango wrote: Add V8, stir.

In my experience, understeer is not always the end result of this recipe

What am I missing here? It's not like you are lending out a 1970s 911 Porch Turbo that is more likely to spin than not, its a MIATA for heavens sake. If Miatae were a menace to those UN-initiaded to RWD, no-one on the planet would not be able to get a good coif anymore for crying out loud!

I would be more worried about handing over a car that has non-factory validated handling traits.

Seriously, if you cant drive a Miata, you should not be driving.

I would never lend a car to anyone I consider a friend who would drive it anywhere near "the limit" without the talent or intelligence to not wreck the car. You wreck my car, you fix it or buy it. I agree - If you can't drive a Miata, you should not be driving.

Yes but it's the OP's car and he has described it as "twitchy" so I see no issues with wanting to make it a little less twitchy while loaning it out. It's not unheard of for someone, especially on this board, to take an otherwise benign handling car and make it very tricky to drive, even on the street. Either for competition purposes or just because they like them a little twitchy.

I see no issues with wanting to make it a little less twitchy while loaning it out. It's not unheard of for someone, especially on this board, to take an otherwise benign handling car and make it very tricky to drive, even on the street.

Definitely! Lots of good suggestions in this thread. I would disconnect the rear dirveshaft and change the tire pressures and see if that is enough.

Disconnecting the rear driveshaft should taking handling out of the picture entirely - at least, once the car gets to the bottom of any available hill

Disconnect rear anti-sway bar and/or go back to OEM alignment while your friend has the car.

Make him pay a damage deposit equal to or greater than the price of the car. Tell him/her that it will be completely forfeited in the event of damage. That ought to take understeer or oversteer completely out of the picture.