So, a 3.63 fuji popped up for 575 shipped complete.
Im not seeing what the fuji diff can hold.
The price, amd drop in ability it definitely appealing if it will hold power like the torsen.
If im honest, car will top out about 350hp with the blower im planning.
In reply to Dusterbd13-michael :
What was your gearing on the old one? I remember is talking after I took it to the Challenge about it needing taller gearing. With the extra power I think so even more.
Think of the Fuji as a slightly preloaded Torsen. Not dramatically different in construction. I'd go with it.
I did the 28 spline limited slip out of a thunderbird. This matched with monster Miata's half shafts and the ford cvs inner and outer with broached hubs. Def the most expensive part of the build
Also as has been mentioned, wheel hop broke my first iteration mount
Stampie: it was either 4:10 or 4:30. Pretty sure 4:10. And i fully agree it needs a taller gear. My guess was 3:23, but..
Keith: what do you mean by preloaded?
Ramirez: thanks! I Swear your 8.8 looks smaller than the one I have. Did you carve anything out of the subframe for clearance?
I forget the specifics, but iirc there's a bit of side load on the gears. A Torsen will only transfer a multiple of the torque on the "weak" wheel, and the preload means that number is never zero. It's been a while.
In reply to Dusterbd13-michael :
I did not carve out anything from the subframe but did add material for strength
so, i compared the 4.30s (based on trap speeds on rev limiter, what i had) to 3.63
Its better. Speeds are still not stellar, but im honestly not sure.
The 8.8 would be similar gearing, until i changed to a 3.23 or something. Which adds another $500 to the swap.
What are y'alls thoughts?
The 4.3 is definitely too low, the 3.63 isn't bad but an even higher final drive could work well.
My diff came with 3.08 gears and a trac loc. Given the cost of swapping gears vs. a thunderbird diff in the junkyard I'd be thinking about a new diff with the correct gears already installed if you go the 8.8 route. Just a thought.
Don't recent Flyin' Miata use a GM rear IRS diff?
Your $100 8.8 was a good deal, but all the extra 'stuff' to make it work is adding up.
I've seen those GM diffs on eBay for pretty reasonable money.
We used CTS and G8 differentials.
I pulled the trigger on the 3.63, and prestige is shipping it.
Easy button. As someone once said here, perfect is the enemy of done.
Dusterbd13-michael said:Easy button. As someone once said here, perfect is the enemy of done.
I'm-in-this-picture-and-i-don't-like-it.jpg
Why 6k redline? We shift at 6200 or so if needed. That should add some mph.
To be clear, we have the same engine / Trans and our rear-end ratio is 4.1.
We don't get to 130mph on most tracks. We would need to drive road America or Daytona to get higher than that.
In other words, I think your fine either way.
wvumtnbkr said:Why 6k redline? We shift at 6200 or so if needed. That should add some mph.
My rev limiter hits at 6k, which ive always felt was low. It honestly feels lower than 6k, but thats what the tach reads. Its still pulling strong when the limiter hits.
Michael, I know you already ordered another Miata diff but in the future, another option to look into might be a Lincoln Mark 8 diff. It's an IRS 8.8 that might be smaller than the Explorer diff. Pretty sure they are 28-spline rather than 31-spline like the Explorer. Would probably have more of a highway gear ratio too, I'd guess 3.08-3.27.
untchabl said:Michael, I know you already ordered another Miata diff but in the future, another option to look into might be a Lincoln Mark 8 diff. It's an IRS 8.8 that might be smaller than the Explorer diff. Pretty sure they are 28-spline rather than 31-spline like the Explorer. Would probably have more of a highway gear ratio too, I'd guess 3.08-3.27.
That is the diff that I used. Along with MM halfshaft assemblies. Made life ea$y.
All Mark VIIIs come with open diffs and 3.07 gears. The carrier itself is identical to the T-Bird/Cougar one, but aluminum instead of iron.
As for that failed diff mount above: Was there any kind of bushing there? Hard to tell, but the factory 8.8 rear mount has rubber to cut down on vibration.
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