Yeah, that's the kind that came with my Getrag swap kit. Had a decent bit of runout as well, although I don't have a video of it unfortunately.

 

Getrag diff or getrag trans? and what diff with trans?

Trying to decide if i give this another go, vs going DSS cv driveshaft. or crazier and do a 2 piece.

 

ZF6 trans with Getrag G80 diff.

2 piece seems like the move from here. I remember Greg saying a CV driveshaft didn't fix his issue.

 

I have no direct experience, but after following along with folks on this forum and Greg on YT I agree that I'd just straight to the 2pc option.

 

Did you toss your giubo that came with the trans? I threw mine away the night I received mine (dumb) and regretted it after some folks started surmising that a 2-piece driveshaft was the key to eliminating the vibration.

 

I'm still amazed everyone else had vibration issues. Both driveshafts he sent me were fine. He must have switched suppliers.

 

At this point I'm amazed that yours didn't! I can't say I've seen too many of these swaps that don't have this issue at this point, including the k swap car owner I met.

 

Smooth and strong at 150 mph. But scary as f*** because the car was so small.

 

Lol any tips or things im missing here? Getrag or Miata diff? PPF delete? Adapter on trans or diff? ZF6 trans? What driveshaft?

 

ZF6, Miata diff, stock diff mounts, modified stock PPF to bolt to topside of trans crossmember. Pics near end of my build thread called Slow Torture. I doubled up parts of the PPF for strength, and those pics are there, too.

 

ah yes, the infamous sixshooter "heard you like ppf's" setup. Sorry to see you sold the car, glad you are still around.

Unique to your car obviously was the diff mount, but even then you still had to ensure diff pinion angle matched trans.

Wondering if you got extra lucky on the driveshaft and thats all this simply is or what?

 

You could always have one made locally.

 

I bought Six's car

It's fine up to around 120mph and then I am also having vibration issues. It's tolerable but makes me think I'm going to break something. Glad I'm not seeing the same 60mph stuff y'all are at least.

I will admit I have been towing the car with a dolly, so disconnecting the driveshaft regularly. I am wondering if maybe Six just had the rear mounted perfectly and my messing with it has created an issue.. or if his tolerance for vibrations is just much higher than mine haha.

 

This is good information ^^ Wonder if you can see any runout in any of the components with the car idling in 1st or second on jack stands.

Goose, what's the latest?

 

It was smooth at 150mph previously, so maybe.

 

Well, I was sent the latest and greatest KPOWER 3.5" Aluminum driveshaft from their new vendor Dynamic Drivelines. I installed this onto the car with all other stuff remaining. 60mph shake went away. Took it to the track for the weekend and it now shakes around 100-115ish.

This new aluminum driveshaft is def much better built all around. Slip joint is now at trans side and is supposed to be bigger and tighter. However the U joint on the transmission side is too big/short and you cant use lock washers under the allen head bolts, and installation is a 13 out of 10 pain level. You have to cut down a 5/16" allen key and have to walk each one in a little at a time because there is no room otherwise. Really needs to be redesigned and feedback sent to KPOWER.




KPOWER then suggested me to replace the old aluminum ZF6 to driveshaft adapter to the new steel version. Old aluminum one had the tiniest bit of slop between driveshaft and recess in adapter.. But it had zero runout measured on its edge. Installed the new steel one, super tight tolerance shaft to adapter. With bolts installed i can not get it to seat with cut off allen key on the car. With driveshaft/trans/ out of the car And articulating the front U joint i can put a long ball end socket allen with impact on the bolts. I can get it to seat like this, but cant make this happen on the car. When on the car, driveshaft wont seat, and new steel had visible runout and shook the car as bad as day zero.




This is the latest, lol.. waiting on KPOWER from emails on the weekend.

 

Holy hell, well I'm glad it was at least good enough to track last weekend.

I thought my setup was hard enough to secure with those allen bolts. That's incredible it's somehow even tougher to do with that new driveshaft lol.

 

Ahh realizing my photos didnt upload.

Old aluminum left, new steel right.


The furthest i could seat the driveshaft into the new steel adapter on the car....



Incredibly tight tolerance between allen bolt and u joint on trans side. (photo from previous aluminum adapter on the car)




What im realizing tonight is that the new steel adapter has too tight of a pocket compared to the older aluminum one. I think a bit tighter to reduce slop is good but this is too far. Also the bottom of new steel adapter pocket is smaller then the top/opening if that makes sense (sides arent parallel).

• Old Aluminum Adapter ID- 60.39 would be my best guess
• New Steel Adapter ID- The pocket sides are not really parallel are there is a small radius at the bottom, of the pocket. The base of the pocket is smaller then the top opening if that makes sense. Very hard to get a consistent reading. But if i had to say a number at bottom it would be 59.80 And at the top/opening 60.36

• Both have a depth of about 3.33

• Outside diameter of the driveshaft-60.32 ish.This is a more consistent thing to measure.

 

Quick Update-

KPower realized the pocket is too tight and sent a new driveshaft adapter with a deeper pocket. Received this and reinstalled. Also realized the chamfer on the backside was missing which was also preventing it from seating flat due to the transmission pin having a bit of flare.

Reinstalled new adapter and aluminum driveshaft went to an event, never really was able to hit 105-115 to see, but 60mph is def gone.

IMHO there is still a bit of visible runout in the adapter. Just enough play in everything and its never going to be perfect.

Should be back on track end the month where i can test higher speed vibration.

 

Update on my end, went to the track but was unable to try anything. Was bleeding brakes and noticed front hubs were not in great condition so loaded the car back up and never drove it. Have another event in August but hopefully will test it out before then. The elevated expressway here is a fun place to find triple digits at night lol.