Turbo trans to NA diff CHEAPER idea?? Someone has had to have thought of this before?
 

Okay, so I'm currently going through a TurboII swap, and am going to run a Tii tranny, but didn't want to switch out my NA rear end, because it's an expensive aftermarket 1.5 way.

I know you can buy the Tii tranny, to NA diff driveshafts for around $300??

I read a few threads saying that you can use the Auto driveshaft, as it has the yoke size of the Tii tranny, but the NA Diff PCD on the other side.

The problem with that is, it's ~1" too short?

So here's my idea.

Attachment 649489



Kinda like a billet wheel spacer adapter. But for the diff. Obviously.

What it would do is basically the same as the wheel spacer though. Retain the mounting holes, but push the driveshaft an inch in the correct direction.

Has anyone ever thought of this, or made something like this??

Please tell me this is a great idea :icon_tup::icon_tup:

Auto drive shafts can be had for like $30, and this adapter couldn't cost more than $50-60 to make. Meaning this would be a super cost effective solution right??

I am thinking there may be an issue with it not being balanced. If you could bolt the piece to the driveshaft as it woiuld be on the car then take it to a driveline shop and get the assembly balanced it might work.

why not take the Diff flange off and see where the holes correspond to the TII Driveshaft?
You can make the holes on the driveshaft Bigger(oval them) ..BUT fill in the old spot where the original TII bolts went through with a weld job.

Then again you got a $1k Diff in a N/A Rear end and you are complaining about matching it to a TII swapped car that cost you money to do.
Not to rag on ya but That statement is just to point out that if you are doing that much to the car you may as well Complete doing it RIGHT and don't fart with stuff that can be "iffy".

1: bought the car with the diff.
2: swap has taken me months to even begin. And am not even half way through. Not much money to play with
3: never once complained.


Okay so let me make my intentions a little more clear.

It can take forever to find a Tii driveshaft, and when you do find them. They're beat up, and cost a fortune. So a Tii shaft would just not be very cash friendly.

Also, many many people already use the $300 driveshaft. I'm simply trying to replace it with a $100 MAX solution. Who doesn't want to save $200??

There's tons of unwanted auto drive shafts that can be had for pocket change. Why not put them to use, and save money at the same time?

I bought a used t2 driveshaft and it had the holes ovaled out since he was using it on a NA rear end. I'm assuming he had no issues, and I'm using it fine now with a t2 rear.

I dont know about Tons of them being out there and in serviceable condition but let us know how it works out

Ya,I mentioned that,but Personally It doesn't sit well with my gut,so I don't fully suggest with doing it.
It can be done but not on my car.I still have a Driveshaft in my shed that someone did that oval hole mod to.
IDEA!:I may just get it welded up..sell it as a conversion.

I ran an ovaled out TII drive shaft to my NA rear end for a couple years with no issues. I recently swapped it out for a legit conversion shaft since I'm planning on selling the car and it will be one less thing to discuss with the next owner. When I swapped it out I saw no evidence of the ovaled out holes causing any issue with the bolts loosening up, or the flange shifting/spinning out of alignment/, or any other causes for concern that it was going to come apart and kill me.

beachFC - I'd ship you my ovaled holed TII drive shaft for the cost of shipping if you'd promise not to sue me if it all falls apart and maims or kills you. :lol:

^BAM. Done.

In the interest of science, the adapter idea could work. BUT it requires you to get two things right:

1. The adapter needs to be balanced. That means holes need to be machined and drilled very accurately and all the geometry is symmetrical. To do it perfectly, you'd need CNC machine time and/or balancing afterward. Basically you are building an tiny solid driveshaft, so it has the same balancing requirements.

2. Threads need to be cut straight, because fasteners don't like rotating, misaligned faces. Again, this is hard to do by hand.

Also consider the residual value of the parts if you do the TII diff swap. Your spacer is worth 0 dollars while the driveshaft could be sold for ~$150? You're not that much further in the hole.

exactly this part needs to be very accurate or it will vibrate,

my dad and I build a getto adapter back in the day and it had a ton of vibration, but it did allow us to at least get the car rolling, until proper items could be installed,

however strong vibration could put stress on the bolts and drivetrain and cause them to break,
you don't want your driveline exploding going 60 mph!

I've personally seen them sell for $10 in great condition. Where as I've seen TERRIBLE condition Tii driveshafts sell for $70. I mean BOTH u-joints had major play in them.


Mega down for that deal. But it's not gonna keep me from pursuing this spacer idea haha..


1: I have 3 buddies that work in machine shops, One at Jet engineering(who make parts for Boeing I believe?? not sure) and 2 at privately owned smaller shops.

2: I also work at NRG Innovations. The company that produces the hub adapter, and quick release steering wheel systems.. We have MORE than enough CNC machines at the ready hahaha :D The factory where our sh*t is made has about an acre of warehouse filled with them. But i'd only really go that route if they were going into production.



Again, I am NOT trying to come up with a completely new idea. The drive shaft is already 100% available, and in production. I am simply trying to come up with a easier, and more cost effective way to adapt the two driveline parts. How is nobody else on board?! :scratch::lol:

selling adapters might be profitable, id agree,

no ones on board cause all of us who are posting have already moved passed this point lol

make your adapter and become rich! if you sell enuf u can afford a new t2 diff and lsd! lol

we could call it the "son of a Beach FC driveshaft adapter!'

heresa drawing I modified,

use longer high grade bolts, then make a hole in the middle cuase the stock diff flang has a centering section that sticks out, and then make one that sticks out on the other end to go into the stock auto driveline.

like hubcentric wheel spacers,

Not worried about making profit. Of course that sounds interesting, but I've just never been that type of guy. More of the "pass on a deal to a fellow enthusiast" kinda guy. I'd really only want to charge enough to cover the cost of production.

As for the "not on board" deal.. I wonder why there was enough interest for a known company to spend big bucks, and produce an entirely new $300 drive-shaft, but not enough interest to make a $50 adapter. :scratch::scratch::scratch:



:nod: :icon_tup: "Son of a Beach!" sounds attractive ^_^

Aside from the bolt hole stuff, that was all part of the plan. I wanted it just like a hub-centric wheel spacer. I mentioned that in the first page, but included no detail. I guess I thought that everyone would have got that part :blush:

For some reason the longer bolts scare me. Seems like if you were to get even the SMALLEST amount of play, that the bolts would have enough force to snap like tooth picks, and ruin/oval the holes on all the pieces, and opposed to the ruining of two pieces if the bolts were to snap on the original plan.

Not sure if I'm way off on that one. But my mind seems to see it happening??

I dont know how the adapter will handle the driveshaft angle aspect of the operation , in my head it sounds like it would work , then I over think it and I picture vibrations

( CNC is simple for this, if guys cut wheel spacers for $50 a pair how much more complicated is threading some of the holes ? )

Well that's the thing. I WANT the holes threaded. As seen in the first picture.

As for vibration, I doubt there will be any to speak of.. not sure how off a forged billet aluminum spacer could even be. But probably next to nothing at all.

Because the factory driveshaft has non-replacable U-joints( I know there is a way to replace them but it requires some grinding and extra steps that true replacable ones don't). They "Mazdatrix" were already selling an aftermarket driveshaft with true replacable U-joints before the popularity of the TII swaps happened. So to sell one to adapt the two was just as simple as offering the option of the n/a flange on their TII shaft or vice/versa. Also from a liability standpoint the risk, even if small, of something failing on the adapter and getting sued over it if someone was injured was probably not worth the effort to develop it.

when going to the expense of a properly done swap, a driveshaft is a minor expense in the overall scheme of things

I can hate to pay for things as much as the next guy so I can appreciate some grassroots money saving techniques. Set one up and use it for a while and see what happens but you wouldnt be the first to say "hey how come they dont make a spacer"= maybe you need to be that guy who makes it

That does make sense. But my point is that, people BUY the thing. For $300. Is saving $250 a hassle?? I sure wouldn't mind.

As far as getting sued?? I highly highly doubt it.

Companies already sell a similar product, and even goes on the same section of the car(Drive line). Wheel spacers. If Daigo Saito can launch a 1200hp car running 285 Achiles 123's on an a 75mm!!! billet wheel spacer. I'm quite sure anyone doing a budget Tii swap can't come anywhere near the amount of power it takes to destroy one.

the guy that is such a cheap ass to buy this spacer cant afford an attorney, you could always just advertise this for off-road testing purposes only, use at own risk,as-is no liability bla bla

make it!

I never said anything about a hassle. I just stated why I think they sell driveshafts and not adapters. They already sold driveshafts. For them it was probably a phone call and/or a new drawing to their vender saying we want to order x-number of driveshats with this flange on them. This, I'm sure was less cost for them than developing and building a prototype and then testing the adapter before offering it for sale.

Even if there is no chance of failure which there could be even if as small as 0.1% lets say, you have to take it into account as a business.

Personal injury lawers usually get their cut from your settlement if you win your case thus you don't have to have any money to sue. They only get paid if you win. You lose they and you are S.O.L.

Don't misunderstand. I'm not telling him to not make it for his build or even sell a few if it works out. I was just saying why I think they don't sell adapters. His chances of getting sued may be almost 0, but some people see a successful business and they see $$$, and here comes the lawsuit even if there is no grounds for one.

Sorry for derailing the thread.

Just oval the bolt holes

Get a turbo2 drive shaft!Take off the NA flange off the diff and mate it 2 the turbo driveshaft.If you look carefully the flanges will be centered but the holes wont match.Clamp them down together and redrill oval the holes a little and your done.7 plus years off street racing,dyno pulls,drag racing and my setup was still running with the above mod and never had a vibration or anything!well i did destroy the NA rear end eventually did install a Turbo 2 diff....thanks 2 the newly found power after my REW RE hybrid swap.

Or like I said just oval the holes. Lol

And just a bit off topic, even if he has an upgraded lsd, it will still be prone to grenading stub shafts right? Seeing as they are like a baby's ankle.

there's multiple ways of doing this which are listed here already, without using the short automatic driveshaft.

i would also worry about balance with a fabricated spacer, it would have to be milled to the perfect size for the yoke centering pilot hole. then the material weight plays a role, steel would be heavy and throw balance out easier, except it would be cheap to make and sturdy.

aluminum would be better for balance but would i trust aluminum for this job? likely not since the pilot holes would take up half the thickness of the adapter which will weaken the already somewhat weaker material. the cost would be multiple times that of the steel adapter. even a billet chunk for the job would be about $25 before machining.


while being a good idea it just would create another fork for possibilities, and still not being one that is the optimal route or even all that much cheaper in the end.

i also never much cared for the TII to n/a driveshaft, the rear u-joint is still only as strong as an n/a part. if you've checked these staked joints the n/a joints are VERYYYYY small/weak. even the TII staked joint is still smaller than the 1972-1982 joints that were replaceable. the 1979 shaft i just rebuilt was the most recent one that still felt like an actual driveshaft, the '83 shaft(non serviceable/staked) i rebuilt several weeks ago the joints felt like tinker toys.

Other people don't do it because they do not have free access to a $50,000 cnc milling machine. It may cost you $50 but it costs the business $500 to pay the employee to create a program, buy the material, buy the cutting bits, buy the taps, rent the building, maintain the machine, health insurance, facility insurance, machine depreciation, electricity, etc.

Driveshaft "technology" is well established and readily available, thus cheap.

And what's the difference between a used auto driveshaft and a used turbo driveshaft?

Out of curiosity I looked at Mazdatrix's site and they use the same U-joint for all their aftermarket steel driveshafts. I take you were talking stock parts so hopefully their part solves the potential u-joint strength issue you mention.

length, the automatic is a physically longer transmission so the shaft is shorter than the turbo shaft is.

if the difference is 1", you could theoretically use an auto shaft in place of a turbo shaft but the insertion won't be full depth and some additional spline wear might take place. a driveshaft shop could also simply replace the tube to meet the length that you need and rebalance it for probably $100-150. for those who need a turbo shaft and can't find one this could be a possibility.

it's been many years since i actually used the adaptive driveshaft but i somewhat recall the joint being 2 sizes to account for the different yokes. it's possible they moved on to making a new rear yoke altogether(or one from a different vehicle which fits the n/a pattern) which accepts the joint on the turbo shaft. the straps around the OE joints is too thin to be machined out for this to be possible if they didn't. either that or they simply forgot that there should be an exclusion for the modified shafts.

My bad, I meant the difference in "condition" of a used NA auto 25 year old driveshaft vs a used turbo 25 year old driveshaft. :beerchug:

The either way, this setup still retains all the weak points of the NA drivetrain.

They sell the flanges seperate now and list them as replacements for their aftermarket shafts only, so maybe they did move on to making a new rear yoke altogther.

probably right, they likely use different yokes altogether since none of them interchange with the OE parts anymore. too bad this still eliminates the probability of making your own hybrid shaft with a standard turbo front section. a rear yoke and joint being about $65, working around the staked shaft is still manageable.

All this talk of CNC being needed and balancing is kind of laughable...

You think all aftermarket pulleys are balanced? Nope! You think all of the wheel adapter and spacers are balanced? Nope!

If you are skilled, the spacer the OP is talking about would be easily built on a GOOD drill press. Not some dewalt/HF/Home Depot drill press. Any day 1 machinist can make this on a manual mill in about 5 minutes.

As long as the center hole is concentric to the outside diameter and the 8 holes are evenly spaced around the entire circle. It will naturally be balanced.



BUT... Just wait and but the TII to NA shaft in the classified section. They come up every so often for around $100. I have bought 2 on here when i needed them. You say it might take a while to finish. just wait for one to show up...

that assumes that the yoke itself would allow it to be perfectly balanced by just being concentrically placed. i wouldn't trust that to be true, with the weight of a 1" spacer strong enough to handle this job.

it might work, it might not. only one way to know for sure, but the next question is: is it worth the effort if it doesn't work and the whole assembly needs to be rebalanced? from a shop perspective i would say this isn't a worthwhile endeavor for such a low possible volume in sales and small profit to be made off the part.

i spent weeks/months in R+D on those seal savers and about $1k in costs, years later i haven't even sold enough to make a profit so i haven't even bothered making any more. i guess i should take it out of my signature, heh. the market here is very small, with something like this it is even that much smaller.

there is no good answer to this issue anyways. JDM engines are most commonly installed, they sometimes come with the turbo transmission but no driveshaft, so you'd have to buy a turbo or automatic driveshaft, why bother with the auto shaft and an adapter? you'd still spend $150 to make that work, or spend $300 for a hybrid shaft. or use the non turbo transmission and everything bolts together. or do it right and install the turbo diff and half shafts. all this arguing over one very out of the way possible workaround which hasn't even been hammered out yet to save a few bucks.

what i'm getting at is i can't foresee lines of people tripping over grabbing a driveshaft adapter, when you first also need the auto shaft to start with. the mazdatrix shaft is already serviceable and the u-joints already replaceable.

I'd personally start the project in a lathe but yes, it is simple enough to be done on conventional machinery. The spacer could be made to take up the 1" difference in the length of the shafts also.

I very much agree about starting it on a lathe. But there is no every man's comparison for a tool like a drill press in place of a mill. So I left it out. I still believe that this can be made easily on a stout drill press with patience.

A hack job, maybe.