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Old 09-12-2016, 04:58 PM   #1
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Default ITT: We discuss T5 swaps and other information.

Well I finally bought one. 110k on it from an 02 mustang. Paid $300 for it in oregon, your prices may vary.



I'm going to start out with some information I have gathered from around the web. Mostly from Savington's thread.

Quote:
Originally Posted by Savington View Post
A quick change of direction, and a peek into the future. One of the many things we'll use this chassis to develop is a T5 swap kit, and this is the beginning of that development. The box is a -238 code from a 1996 3.8L Mustang, which is desirable for a few reasons:
  • It's a World-Class box
  • It has a 3.35 1st gear which means that you can swap the input shaft from a 3.35 V8 box into it with ease.
  • The 0.75 overdrive is a big step down from the .843 in the car now, but not as deep as the .63 ODs in all the V8 boxes
  • It has an electronic speedo sender, and with a Dakota box and a little work, it should talk nicely to the NB speedometer and MS3
  • It was $130 at the junkyard, not $800 like all the V8 boxes are
I snagged this after confirming with G-Force that it's a suitable candidate to build later on. They actually said it's more desirable than an older V8 box as the basis for a built gearbox, since the newer V6 boxes are typically in much better shape.

For people who want a 100% bolt-in solution, you'll have to shell out $1100 for a new T5z box, but converting the V6 box to V8 spec is easy. You need the input shaft, bearing, bearing cover plate, and a shim kit, all of which can be had for ~$140 or so, which means you can put the gearbox itself together for well under $300 without any special one-time deals or hard to find parts.

The clutch disc was $110 and it's a performance organic disc with a 10-spline T5 center. It will get swapped for a 26-spline piece when I do a G-Force gearset next year. All the G-Force boxes are set up around 7.18" input shafts (V8), not the ~7.8" shafts that came in the V6s, so in order to accomodate built gearboxes, we'll build around the 7.18" length.

The bellhousing is cut off a blown 5-speed (everyone considering this swap probably has a blown 5-speed in their garage) and it will be milled down to the correct length and welded to an adapter plate which will be done in a few weeks. Using a chopped-up OEM bellhousing means I can retain the stock TOB, stock clutch fork, and stock hydraulics, so from the front, it will look like a Miata transmission with a 10-spline input shaft sticking through, and there are no issues with reliability or fitment on any of those critical items.

So that's the trans>engine attachment all sorted out. Next big puzzle is the shifter extension. The PPF bracket should be a little easier.

Quote:
Originally Posted by aidandj View Post
Necro post. My research shows that the 94-98 boxes were from the 6-232, and the 99-04 were from the 6-238. And thats when the electronic speedo switchover happened. Am I totally off base?

Correct me if I'm wrong.

90-93 V8 box = correct length input shaft, bad overdrive. More $$$ because mustangs like em.
94-98 V6 box = Longer input shaft. But good overdrive. Uses 3.35 first gear so we can use a v8 input shaft. Mechanical speedo
99-04 V6 box = Longer input shaft. Good overdrive. 3.35 first gear, but with electronic speedo.
94-95 V8 box = Longer input shaft, bad overdrive, 3.35 first gear
Quote:
Originally Posted by Savington View Post
Quote:
Originally Posted by aidandj View Post
Wow there is all sorts of conflicting information out there.

Going to edit this post instead of continuing to fill up your thread.

Auto/Man Trans Gear Ratios for V6 & GT ? - The Mustang Source - Ford Mustang Forums



But then according to this: http://www.mongosgarage.com/tech/t5/T5Numbers.PDF the 98-99 had a .73 overdrive. and the 99-01 doesnt have ratios listed.

I guess unless I can find some real info the 94-98 is the safe one to go with. And I guess the 96-98 had the electronic speedo?

I wish other platforms had a version of mt.net, with actual fact checking instead of just numbers.
Why I chose what I chose:

I picked a 99-04 box for a couple reasons, the main one being strength. It has the stronger gears of the V8 box, with a .68 overdrive. This is a little low, but I'm hoping it will be manageable. It has an electronic speedo sender, which can be used to connect to a megasquirt and an NB cluster. It was also cheaper than the 90-93 boxes that are more popular.

I'm going to swap in an input shaft from a 90-93 box, which will give me the same dimensions of the Astro A-5's which can handle 485+ ft/lbs.

Plans for the swap:

I'm going a similar route as Savington. I will chop off a spare miata bellhousing. Build a 1/2" flange that matches the t5. weld the miata bellhousing to the t5 flange. Get some clutch discs for the twin disc that fit the mustange input shaft. Aquire correct pilot bearing and make some sort of throwout bearing work. Use stock miata hydraulics.

Some sort of PPF adapter.

Plan for the shifter: Pop out freeze plug. Build extension rod that connects to the shifter inside the box. Keeps the dentents in the box. Send a shaft out the freeze plug with a bushing and an oil seal to keep the oil in. Mount a shifter back behind where the miata shifter goes. Hope it doesn't interfere with the driveshaft.

Somewhere along the way I will screw up horribly and fail, but at least it will be documented!!!

Post questions and information here!

Parts and other information: https://docs.google.com/spreadsheets...it?usp=sharing

Last edited by aidandj; 09-15-2016 at 10:48 PM.
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Old 09-12-2016, 06:27 PM   #2
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I am in for results. I was discussing this swap with a well known miata fabricator because I wanted him to use my car as the guinea pig for a kit he could offer to the community. He ended up deciding that his other projects had a bigger market and were easier for him to deliver in a way that he could sell so he chose not to pursue. Very disappoint.
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Old 09-12-2016, 06:57 PM   #3
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Is there a future SADFab opportunity for those who do not have such facility for magic?
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Old 09-12-2016, 06:59 PM   #4
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Nope. Andrew is working on a kit for people who would like to pay.

This thread is for my personal transmission swap, and for information for others to use along their way.

My next research step is going to be pilot bearing. I'll measure a stock bearing tonight and the input shaft of the t5 and start searching.
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Old 09-12-2016, 08:52 PM   #5
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Subbed for awesome info
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Old 09-12-2016, 08:54 PM   #6
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I know Leafy has some good information in this area.

I have some stuff laying around in my build thread I will try and dig up also. Some good pictures of machining shift adapters.

And the only person I personally know of with a t5 in his miata: TurboTim
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Old 09-12-2016, 09:11 PM   #7
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I just made some pilot bushings for mine. Bought some oilite the right OD for the crank and had them reamed to .670+.002. But that was for the 19mm OD MZR pilot bearing. If the bp is 24mm then the mustang one just works.
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Old 09-13-2016, 12:45 AM   #8
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Subbed for this. If anyone in chicago land is also interested let me know. I have a couple of extra bell housings. We can be the midwest development arm of Halfast Racing. (wholly owned subsidiary of Mickey Mouse Motorsports.
I think the .68 fifth should be fine with 250+ hp cars.
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Old 09-13-2016, 12:48 AM   #9
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I think the belhousing is going to be the easiest part. Chop, mill, weld, mill.
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Old 09-13-2016, 12:58 AM   #10
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Quote:
Originally Posted by aidandj View Post
I think the belhousing is going to be the easiest part. Chop, mill, weld, mill.
Yeah, I think so too. One of the housings will be sacrificed with lots of inspection cut outs to see how every thing is lining up. Did I see you already got the input shaft?
We also need to find the utube video of the guy that already made the shift extension.
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Old 09-13-2016, 12:59 AM   #11
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Pilot bearing:

Mustang:
  • ID: 0.6721
  • OD: 1.487
  • Width: 0.732
  • Type: Needle
Miata:
  • ID: 0.590
  • OD: 1.378
  • Width: 0.4331
  • Type: Ball
What we want:
  • ID: 0.6721
  • OD: 1.378
  • Width: 0.4331
  • Type: Ball

Time to do some searching and find what we need.
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Old 09-13-2016, 01:00 AM   #12
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Quote:
Originally Posted by 2manyhobyz View Post
Yeah, I think so too. One of the housings will be sacrificed with lots of inspection cut outs to see how every thing is lining up. Did I see you already got the input shaft?
We also need to find the utube video of the guy that already made the shift extension.
No input shaft yet. Savington already swapped shafts.

Nobody has done the shift extension the way I plan, AFAIK. The video on youtube is a bit different. Idk exactly where it was though.
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Old 09-13-2016, 01:11 AM   #13
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Quote:
Originally Posted by 2manyhobyz View Post
Yeah, I think so too. One of the housings will be sacrificed with lots of inspection cut outs to see how every thing is lining up. Did I see you already got the input shaft?
We also need to find the utube video of the guy that already made the shift extension.
Modeling clay for depth. Flywheel+pilot bearing for axial alignment. Then tack it in place probably.

Or just cut a big hole. I have 3 spare 5 speeds right now.
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Old 09-13-2016, 01:21 AM   #14
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Just what i came up with quickly on mcmaster. its only 0.394" wide but would work. Ill dig in the timken catalog tomorrow

McMaster-Carr

17x35x11mm is what were after for those that measure in proper units
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Old 09-13-2016, 01:29 AM   #15
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Old 09-13-2016, 03:06 AM   #16
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Don't recall exact p/n, but AFAIK no 11mm-wide bearing exists. Thankfully the flywheel is only 10mm thick anyway, so I have a 10mm-thick bearing.
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Old 09-13-2016, 09:24 AM   #17
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Quote:
Originally Posted by aidandj View Post
Modeling clay for depth. Flywheel+pilot bearing for axial alignment. Then tack it in place probably.

Or just cut a big hole. I have 3 spare 5 speeds right now.
Or send everything to me and I'll digitize it all. While I do have some T5z and miata 5speed stuff in solidworks, it's not enough for me to feel comfy building an adapter off of. I did them quickly to just have something in my assembly, not to base parts from. I built my adapter from the block models; I made my adapters to convert to a SBFord cranks & bell housing and i'm running all mustang clutch stuff.

But then again, I'm not sure how accurate it needs to be. T5z input shaft was .017" off SBF crank centerline when the bellhousing dowels were aligned.
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Old 09-13-2016, 09:42 AM   #18
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I want to keep my twin disc. And the Miata hydraulics. Getting everything digitized wouldn't be that bad of an idea though...
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Old 09-13-2016, 11:41 AM   #19
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Quote:
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I sent your mom to the moon last night. Ill let you figure out which unit I used
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Old 09-13-2016, 11:42 AM   #20
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Must not have been an inch. You need smaller measurements for yours.
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