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.