Also much cheaper and easier to find.

 

I thought useful Miata ratios didn't exist for the T5. Has that changed?

 

Saved! I've been waiting for this.

 

Thought Andrew had found some g-force gear sets. And if your running 4-500hp and a 3.3 rear end arent the useful ratios a little different?

 

No, because the rear end changes all of the tranny ratios by the same factor, so you can't fix a gearbox that has a hole in the gear ratios. Andrew has a long discussion of this in the previous transmission thread.

--Ian

 

If the ratios are spaced wrong, the rear just changes how fast you happen to be going when you fall out of the powerband.

 

What about this? With the exception of 5th, ratios seem very close to what a miata has (1st is a tad longer, 2nd a tad shorter). 5th seems like it would drop you from 7500 rpm to 4700 rpm on a 4-5 shift, with 70mph highway cruising putting you at 2700 instead of 3500 rpm. If you could get a slightly shorter 5th, would this be too bad? Supposedly it's good for 330 ft lbs. edit- does this mean reliable in a v8 with 330 ft/lbs + mustang weight + slicks + hard launches?

AA251 Tremec T-5 5 Speed Transmission - 2.95 SHD

As an aside, I heard that junkyard T5s are ridiculously common and cheap, but vary widely in terms of strength. What would be a cheap source for a miata, or would we just have to rebuild whatever we find to make the ratios not suck?

edit2- how important is the ppf in all of this?

also, wasn't corky working on this idea years ago? I found posts from 2012 on mnet referring to this idea in the past tense

 

this is the **** you want 485 Torque Ford A-5 Transmission - Astro Performance Warehouse

good gearing when you add the .8something 5th gear option. There's also a 575ftlb version thats even more unnecessary. Now this is probably going to put the shifter too far forward so you would want a camaro t5 tail housing, which should put the shifter in about the right spot, but then you lose the speedo gear in the tranny.

 

Speedo gear isn't an issue. ABS sensors+megasquirt+nb cluster.

 

The new T5 cost $1,295 when I bought it about two years ago. I'll dig out the specific PN and dealer shortly. This is the same piece that we used in the Turbo Mustangs 15/ 20 years ago. The 600 to700 hp did bust a couple second gears and cases, but no often.

I think it is fair to suggest any torque rating can handle an excess of 50%. We had to use a 1.5 margin on helicopter parts, and an easy argument suggests the margin would likely be higher on an automobile. Real racing transmission makers often use a design margin in excess of 5.

As I recall the T5 is seven pounds lighter than the Miata tranny.

The Miata clutch disc can be fit with the 9 spline T5 center piece. The shifter position is about 5 inches off of stock, but that piece was easy and available. The extension can be anything from 3 inches to 10 inches, if desired.

A new TOB sleeve, driveshaft and rear trans mount have yet to be made. I hope to get it all done in 6 to 8 weeks. And the PPF attachment, of course.

Any part, or all parts. Your choice.

Corky

 

how much does that bell housing weigh?

 

You do know the tranny behind the 2.3 turbo mustangs is even weaker than the one behind the v8s and even those broke with the pathetic stock fox body hp right?

 

@Corky Bell, what length input shaft is this bellhousing designed around?

I ask because I have a WC T5 sitting in my garage from an SN95 5.0 Mustang and the input shaft is 5/8" LONGER than the T5 from the 79-93 Fox Mustang. Also completely different than the input shaft GM used for the T5 in the Camaro and such...

For those interested in ratios (from the Mustang at any rate)



I believe the "torque" rating in the chart is the OEM rating rather than the actual physical limit. I don't know the source so take it with a grain of salt.

Shitload of T5 info on this site if you are willing to dig: TREMEC 5-speed 6-speed Transmission Conversion solutions Ford Mustang, Falcon, Cobra, Hotrod, GM Camaro, Chevelle, Tri-5, Mopar Muscle
I discovered these guys when I was looking at putting a T5 in my 1966 Mustang.

 

Is the stock t5 out of the v8 fox bodies only good for 300 ft/lbs? The 6 speed is good for that in our cars too.

I'm confused now.

 

That's part of the reason I posted that.

 

It's almost like there's a reason this hasn't become the popular swap by now. Almost

 

Its not 500 ft/lbs for $50? I'm out.

 

I'm going to defend corky on this one.
The Miata community has dropped the ball on a strong transmission solution completely.
There are plenty of high powered 5.0s punishing stock t5s without issue. The reason they aren't a common choice is because the hotrod community couldn't give fewer ***** about miatas, and most of us are either content with 6 speeds or put the effort in adapting T2 trannies.
There are also one million billion versions of the T5, so standardizing a solution would have to take into account many variables.
Also, upgraded gear sets are a thing that is actually available for the T5.

 

Don't get me wrong, I'm not trying to attack Corky I just wanted to throw some gearset numbers out there. Everyone seems to think all T5s are created equal, and they definitely are not.

 

The couple we broke in turbo Mustangs were V8 Mustangs. R&T Mag timed our mustang at 185+ at the Firestone test track in Fort Stocton, Texas. We later put one thru the 1/4 mile at 10.85 @ 121mph. These were equipped with the Super Duty T5's. "Super Duty" implied a change in the synchro, as I recollect.

The correct T5 will do the job okay. The wrong one might not.

It won't be tough to chase down the right one's. I'm out of town presently, but can supply a few more details in a couple days.

I'll check the shaft length and report. Spline, Pilot brg, TOB sleeve, etc......

The weight was about 25 pounds. Next piece will drop 2 or 3 with minor changes. If requested, I can make the housing out of aluminum, after another look at strength needed.

On trying to check this thing for adequate strength, I've been stymied a bit regarding where the loads come from. It seems to me the worst case will be an out of balance driveshaft. I don't have a feel for how far out the balance can get and still be useful, but looking at it from the standpoint of a fatigue load that will kill the shaft eventually (quickly) will not hurt the steel bell hsg. I think adjusting a couple thicknesses will allow aluminum to be okay as well.

Some thoughts on what loads might gang up on it other than a driveshaft misbalance, would be appreciated.

corky