"Project Miata" Update

[erod550]

Can you post a picture of the diff? I think I might have VLSD after all. The other day I was stopped on a dirt road and hit the gas and I could have sworn both tires were spinning. But I may have been mistaken.

[roninsoldier83]

Can you post a picture of the diff? I think I might have VLSD after all. The other day I was stopped on a dirt road and hit the gas and I could have sworn both tires were spinning. But I may have been mistaken.

Actually, a lot of people with open diffs claim that since the car is so well balanced that they will leave two stripes instead of one, so it's pretty common to spin both wheels. It's more of a test to see if the inside wheel spins under hard cornering.

Either way though, you can find all the info you need about identifying what diff you have in the differential spotters guide:
http://www.miata.net/garage/diffguide/index.html


Although, the easiest way for us 90-93 guys to tell is by simply looking at the stub axles. It's actually really easy, as on the VLSD, your driver side stub axles will have "ears" like this:



Also on the VLSD, your passenger side stub axle will have ears that are a bit off-set per se, like this:




In contrast, if you have an open diff, both of your stub axles will have symmetrical/equal length "ears" like this:




The stub axles are all proprietary to the differentials they go to; you can't mix & match them (I've confirmed that with numerous sources, FM being one of them), so without pulling the diff, that's by far the easiest way to tell. All you have to do is merely look at where the axles meet the stub axles, and it's very apparent.

Hope that helps.

[roninsoldier83]

On a separate note, not too long ago I decided I was going to swap out the red conical foam filter with a more traditional cotton gause air filter (i.e. K&N style), since the old one was filthy. Seriously the previous owner really was a lazy guy... you may not be able to tell, but this filter, which is now black, used to be bright red:




^^^No joke. Bright red. Either way, he also pulled the exhaust manifold heat shield off for no apparent reason that I could see.... ?!? So, in the little space I had to work with, I couldn't find a K&N that would fit, but found a knock-off that worked just fine, and was just a bit bigger/more surface area. While I was at it, I put the exhaust manifold heat shield back on, and also changed a few fluids over to synthetics while I was at it.

Honestly, I've been flogging on cars long enough to know when something is just a placebo effect. I wasn't even expecting any noticeable difference at all, but boy was I shocked when I gave it some gas, as the car really pulls a lot harder up top! Before, it almost felt pointless to shift past ~5500rpm, as the car felt like it was choking... I just thought that was normal for this car up here. As it turns out, I was wrong, the car now pulls MUCH harder above 5500rpm, it actually gradually pulls harder and harder towards redline, and almost feels like redline should be a bit higher than ~6500, as it feels like it would keep pulling hard to 7k. Below 5500rpm it feels pretty similar to before, but above 5500rpm it really was choking for air, and now pulls a lot harder.

I was shocked to say the least. While I know the old filter was pretty clogged, at the same time, I didn't think I would actually be able to discern that large of a difference. I doubt the heat shield really did much of anything, but hey, maybe an extra pony or two for deflecting a bit of heat away from the filter haha; but really, I wouldn't be shocked if the car picked up another ~10hp or so, no joke. New synthetic fluids might have contributed as well, but I'm pretty sure 90% of the gains were from changing the uber-clogged filter out with a more free-flowing new/clean filter.


On another note, the former owner really didn't know what he was missing out on. With a bit more TLC, this car has really become far more enjoyable to drive! I've put quite a bit of work into the car since I've picked it up, and am now enjoying it more and more as time goes it; it just keeps getting better!

It now pulls harder, puts down power better (thank you uber-sticky tires & VLSD!), corners harder (negative camber is our friend!), stops shorter/more consistent, and has considerably less NVH than it did when I bought it (there are a few contributing factors to that haha!). It really is a far superior vehicle than it was a few months ago, and I'm actually feeling pretty good about it, as I know it's just going to keep getting better.

Overall, my regret of not buying another MR2 has faded, and I'm actually pretty happy I picked this little thing up. To you guys that encouraged me to keep the car when I was getting frustrated, good call haha!

Either way, just felt like sharing.

-B