99 Big Turbo
 

First time posting, tried a little searching with not much luck for what I'm looking for. I've got a 99NB stock engine, 61mm turbonetics Turbo and MS2PnP. 05 6 speed transmission and a Flyin miata clutch. Looking to change my rear gear ratio next. If some more searching doesn't pan out I'll probably ask some questions in the wrong section of the forum.

I laffed. :giggle:

But also...
https://i.pinimg.com/originals/9d/05...14c2edcf97.jpg

It's going well so far. Lmao kind of a test for now. I plan to build an engine later, but its been a complete DIY so far and I'm happy with it. I've been driving it with the turbo for about two months and I've got it on 12psi now. I think thats about as much as I'm willing to push it. Its plenty fast to say its the stock engine. I just want to do little stuff to the car now. Gears, Axles, Suspension, Better tires.

welcome - and ask away. I just spent the last 4 months going through the pain of changing my rear end from a 4.1 to 3.63 to a 3.3:1. Good luck.

Actually, The 3.63 ratio is what I am hunting. I've seen it new on Miata Roadster for around $700 which is ridiculous. So now I am just kind of keeping an eye out and waiting for a deal.

Welcome to the forum, you'll find lots of good info here.

There's a vendor in the UK who regularly sells complete 3.63 LSDs because they actually came on cars over there. They're still around $7-800 but that's not too bad considering they're shipped from the UK and it's a complete swap. Miataroadster is just selling the ring and pinion

@James Theriot or you can just buy a complete 3.63 torsen from me for $875 shipped.

Well if its going to cost that much i need to know if a rear end like that is going to hold up to drag racing or should I put that $1000 towards a beefier setup.

So Next question, What parts are available to upgrade the stock rear? Axles, solid mount bushings, stuff like that. Or is it a waste of time because the diff is going to explode on a good launch anyway?

I've done some searching but it seems like most people are happy with a 1.8x 60 foot by dragging out the clutch and while I'm not completely against that I'd rather just go.

My car has gone several 1.6x 60's. At the dragstrip I set the launch control to 6000rpm and basically side step the clutch.

I've broken:

The factory axles, the factory aluminum differential housing, and 4th gear in a 6spd.

The car now has DSS level 2 axles, and a fully welded and boxed in differential housing and I haven't had any problem since. The 6 speed trans will hang around for awhile at 300-350whp but you'll kill it eventually. But at $5-600 a pop you can still break one every couple years before you justify the expenditure of swapping to something more robust for a dual duty street car.

My shit for reference:


https://www.miataturbo.net/dynos-tim...r-97746/page2/

That is about what i want to do with the car for now. Except I have no forged internal goodies so same concept just a little slower. What gears are in your car with the 6 speed?

3.63.

If your car is a factory 6 speed the 3.9 that comes with it is fine for ~300whp. If it was a factory 5 speed and has the 4.3 diff I'd still just run a taller tire at the track. I'm still in 5th at the end of the 1/4 mile with the 3.63 and a 225/50/15 drag radial so you're not saving yourself a shift by changing the diff. And all the 1.8 differentials have 7" ring gears so you don't gain any strength by swapping ratios either.

Well I'll definitely be running a different tire. At least a 24.5 bias ply slick, although I'd love to get a 26 on it. If I can get the 26 to not rub then I may even keep the 4.30.

I currently have a set of 26x10s that I'm playing with if I can get them to where they wont rub then I'll order some 26x8s.

26x10 is probably optimistic but I'm sure someone has done it somewhere.

A 24.5 bias ply would be the bees knees and is what I plan to move to after I wear out these drag radials. A bias ply would go a long way to preventing diff housing and axle failures.

How fast do you plan to make the car go? You can get enough MPH to go DEEP 11's (see 2nd gearing pic below) with a 4.3. I'd personally take the $700-800 for a diff and spend 300 bucks on some china forged rods and the rest of the dollhairs on a 24.5" bias ply.

https://cimg7.ibsrv.net/gimg/www.mia...841645f8e1.jpg
https://cimg8.ibsrv.net/gimg/www.mia...dde073a082.jpg

I'd like to be well into the 11s but still be in 4th gear. 26s would make that happen with my current gear ratio. If not then either 24.5 and use 5th or 24.5 and a gear ratio swap to come through in 4th.

I'm running nitto 245/50/16 555r drag radials. Those are basically 26x10. Took lots of heavy hammer action to beat the crap out of wheel wells in places as well a rolling fender lip. They still scrape some with two.people. Will use a bigger hammer next time lol...

You have any pictures or a build thread maybe? Was going to start banging today but rain got in the way. Also need to see what I'm going to do about rear coilovers.

This is the closest thing I have to a build thread
https://www.miataturbo.net/build-thr...exhaust-98666/

Awesome car! I just went and ripped off the factory side spoilers, removed the stock rear coils, and started to roll one fender and my tool came apart. Will fix in the AM. I have a set of almost new D2 coilovers in my shed from a parts car I bought a while back. Do you guys think those would be OK to run on the rears for now, just set to approx stock height and tighten the spring real tight to prevent squat? This is my first IRS car (been through a few mustangs before my kids)

What is an IRS car? Irreversible Retirement Syndrome? Irritable Rearend Syndrome? Internal Revenue Shitheads?

Independent Rear Suspension. lmfao. That just made my day.