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Played around with the car in the driveway a little bit before the rain hit today. I spoke too soon regarding NVH. Post-swap, the cabin started getting more vibrate-y towards redline. I picked up a generic GM hollow rubber transmission mount to replace the solid poly one and swapped it in. Nice improvement! Overall NVH is decreased but the shifter still doesn't move a bit. Come to think of it, I don't believe it can move much due to nature of the shift rod design. The driveline vibration is still present (I didn't intend for this to fix it), but isn't noticeable until another 5mph higher than before, so that's nice...
I also swapped out the Motorcraft Mercon LV fluid that I was running temporarily for the 50/50 Redline D4/MTF mixture that Der_Vierte recommended. Shift quality definitely improved with it!
The more I read and hear from others, it sounds like this vibration is super common from guys running a BP ZF swap with a Miata diff and Kpower PPF delete. I really appreciate Kpower making this swap kit, but I hope there's a solution for rectifying this without swapping to a different diff. Still gotta confirm the driveshaft is balanced and true and then go from there. Will continue diagnosis this week and speak to Kpower as well.
After checking the driveshaft balance and aligning the pinion angle vertically, check the angle left to right. Also make certain the CV axles don't have vertical play at the diff or an imbalance.
I would put the whole car on jack stands and spin it up to vibration speed and eyeball what's in motion prior to removing the driveshaft. It may steer you in a new direction.
It may be something as simple as a wheel weight having come off.
I shouldn't jump to conclusions and completely blame the kit, but it's a bummer that there are issues like this when you're paying a lot for it. Granted my car has some pretty bad vibrations with the stock drivetrain, so who knows.
I suppose it's expected to some extent when you get deep into racecar territory.
After checking the driveshaft balance and aligning the pinion angle vertically, check the angle left to right. Also make certain the CV axles don't have vertical play at the diff or an imbalance.
I would put the whole car on jack stands and spin it up to vibration speed and eyeball what's in motion prior to removing the driveshaft. It may steer you in a new direction.
It may be something as simple as a wheel weight having come off.
'Twas the plan. See below.
Originally Posted by SimBa
I shouldn't jump to conclusions and completely blame the kit, but it's a bummer that there are issues like this when you're paying a lot for it. Granted my car has some pretty bad vibrations with the stock drivetrain, so who knows.
I suppose it's expected to some extent when you get deep into racecar territory.
Same, but I guess sh*t's gonna happen when you have such an extensive list of parts that are supposed to play nice together.
Without further ado, I present to you: my driveshaft runout.
This has gotta be it. I stethoscope'd the driveline while my coworker ran the car at 70mph as well and the noise seemed localized toward the front of the driveshaft. Might be a long shot, but I'm hoping Kpower can just refund me for the driveshaft so I can get a lighter one made locally and save some downtime.
This has gotta be it. I stethoscope'd the driveline while my coworker ran the car at 70mph as well and the noise seemed localized toward the front of the driveshaft. Might be a long shot, but I'm hoping Kpower can just refund me for the driveshaft so I can get a lighter one made locally and save some downtime.
Good job on the detective work! I wonder if kpower builds those driveshafts or if they farm that out.
Next time you have that transmission out I would still get a dial indicator to confirm that flywheel is spinning true and on center. It should really not rely on the bolt holes to register the flywheel to the crankshaft IF that is what they do. I still believe that heavy flywheel/clutch assembly that IF not well balanced or IF not spinning truly on center combined with being spaced further away from main bearing support is a very possible reason why Greg failed main caps on his prior engine.
Thanks, man! It was literally the first thing I looked at when I got under the car haha. I'm considering myself lucky, hopefully that's the only issue with the setup right now. It doesn't show up in the video, but you can clearly see the driveshaft vibrating once the car hits 60mph. The new axles I just put in look true and the only noise I could through the stethoscope in the rear end was a faint resonance of the noise coming from the front of the driveshaft.
I'll scope the flywheel/clutch runout next time the trans is off. You got me thinking now. Luckily, the NVH from the engine doesn't seem magnified exponentially compared to the rest of the NVH incurred after the swap. I don't plan to run 500hp (or anywhere close) in this car ever, so hopefully that places me out of the danger zone if the backspaced rotating mass is an issue with this swap.
KPower told me they outsource their driveshaft duties to another company. I sent them the videos a couple hours ago and they said they'll talk to their manufacturer and expedite me a new driveshaft. If it's going to take 2+ weeks to get, I may have a driveshaft made locally, just so I can (hopefully) race Gridlife on the 27/28th.
Last edited by Z_WAAAAAZ; 04-15-2024 at 06:30 PM.
Reason: ADHD
Man, that thing was way outta whack. I feel for you, it really sucks to pay good money for new parts and have this happen. But again, you gotta realize we're dealing with some pretty custom bespoke racecar parts and **** happens.
At GLTC this weekend I spoke with a guy that had a K24Z3 swap and had an issue with the adapter plate concentricity between the crankshaft and trans input shaft. It took months to diagnose why he had vibrations and eventually blew the hydraulic throwout bearing. Man, KPower just seems to be struggling lately with QC.
I have a vibration issue I've been trying to diagnose and ultimately ignoring for months. At first I blamed the Dorman driveshaft I swapped in, but the FM driveshaft looked almost entirely identical, and the OEM driveshaft has the same issue, I'm left scratching my head. Driveshafts seem to be one of the few things left where a local shop still exists and does quality work.
Hope you get this sorted. $6k is a lot to fork out for a transmission swap that still has issues.
Man, that thing was way outta whack. I feel for you, it really sucks to pay good money for new parts and have this happen. But again, you gotta realize we're dealing with some pretty custom bespoke racecar parts and **** happens.
Yeah, that's kinda where I'm at with the whole deal. Super irritating to have to deal with these issues, but it's also a super-niche kit that's made for old vehicles being turned into high performance racecars. Maybe it's a miracle that everything works as well as it does, even despite the number of bolt holes in my kit that didn't quite line up. This is all cutting into my EFR/Xida funds too, but maybe I should've been wiser and expected some extra costs on top of the kit and fab work that already needed to happen.
Originally Posted by OptionXIII
At GLTC this weekend I spoke with a guy that had a K24Z3 swap and had an issue with the adapter plate concentricity between the crankshaft and trans input shaft. It took months to diagnose why he had vibrations and eventually blew the hydraulic throwout bearing. Man, KPower just seems to be struggling lately with QC.
I have a vibration issue I've been trying to diagnose and ultimately ignoring for months. At first I blamed the Dorman driveshaft I swapped in, but the FM driveshaft looked almost entirely identical, and the OEM driveshaft has the same issue, I'm left scratching my head. Driveshafts seem to be one of the few things left where a local shop still exists and does quality work.
Hope you get this sorted. $6k is a lot to fork out for a transmission swap that still has issues.
Oof, I'd be pissed if that happened on my car. That's a bummer to hear, although the first time I've heard of that happening. This reminds me, I gotta ask my buddy with a K24 NB if he had any hangups with his kit. I can't fault KPower too much, as I'd probably have blown another 6 speed by now if it wasn't for their ZF swap kit. I'm glad they're making this stuff. I'm new to powertrain swaps such as this one, and maybe should have expected more inherent hiccups due to the nature of the beast. Still, it would've been nice to hear from KPower "Hey, we've seen a few vibration issues with the ZF/Miata diff w/ PPF delete setups. You're probably good, but don't plan on tracking your car the weekend after your install, just in case."
I've stated it in my other thread here https://www.miataturbo.net/suspensio...ration-109305/ but RichBobby is dealing with the same issue as I am, and is about to be on his fourth driveshaft from KPower's supplier. All of the driveshafts he's had were either out of round, out of balance, unbalanced, and/or had substantial play in the slip yoke. Due to this, I'm going to have our esteemed local driveshaft shop https://www.drivelinesinc.com/driveshafts make me a driveshaft to rule out any other issues I might have with another KPower supplier unit. I'm planning on eating the cost of this. I spoke to KPower about sending my shaft back and getting a credit toward a Getrag diff swap kit, but they said they have to clear things up with their driveshaft supplier first. I can't fault them for that, no hate there.
Originally Posted by SlowTeg
Ya nice work Zak and hopefully you pinpointed the issue. That driveshaft sure looks to have a lot of wobble.
Thanks man, yeah that's gotta be it. I'm hoping there's no further issue after the shaft is ruled out. I've heard of others having the exact same issue with this swap, and don't want to spend the tail end of our prime track season trying to get my car driveable above 65mph lol.
Shaft is out. Dropping it off at Drivelines tomorrow to have one made based on the dimensions. Also hoping that they can make me one that’s a little lighter as this car’s never gonna push 700lbs/ft of torque. We’ll see.
With the shaft out of the car, the slip yoke feels like it has a pretty minimal amount of play. I didn’t put it in a vice to test though like RichBobby did. I’ll give that a go when I get the shaft back in a couple days.
Wide angle camera on my phone makes my forearm look bigger than it is. Gotta make a mental note of that.
Bro, you got my roomie and I dying over here hahahaha. If this doesn't fix it, my arms might end up looking like that from all the holes I'm gonna punch in my garage wall.
Yeah, that's kinda where I'm at with the whole deal. Super irritating to have to deal with these issues, but it's also a super-niche kit that's made for old vehicles being turned into high performance racecars. Maybe it's a miracle that everything works as well as it does, even despite the number of bolt holes in my kit that didn't quite line up. This is all cutting into my EFR/Xida funds too, but maybe I should've been wiser and expected some extra costs on top of the kit and fab work that already needed to happen.
I gotta say you're a damn good sport about it. Maybe you're cursing behind the screen, I know I would be. There are definitely some issues to be expected with these swaps but with that said this stuff isn't that cheap and having to elongate a bunch of holes + bad driveshaft and other things.. you'd think the least they could do would be to credit you the damn driveshaft that doesn't work for ****.. Ya I get it though what can you do. I'm sure when subbing many different things/parts out it's hard to verify parts are in fact good and quality control is tough for small bizs. This sort of stuff definitely scares me away from any serious drivetrain swaps (on top of the costs). Hopefully you get it sorted but I'd definitely press them a bit on giving you credit for the driveshaft. Sadly, the squeaky wheel gets the grease.. just how things are at times sadly.
I gotta say you're a damn good sport about it. Maybe you're cursing behind the screen, I know I would be. There are definitely some issues to be expected with these swaps but with that said this stuff isn't that cheap and having to elongate a bunch of holes + bad driveshaft and other things.. you'd think the least they could do would be to credit you the damn driveshaft that doesn't work for ****.. Ya I get it though what can you do. I'm sure when subbing many different things/parts out it's hard to verify parts are in fact good and quality control is tough for small bizs. This sort of stuff definitely scares me away from any serious drivetrain swaps (on top of the costs). Hopefully you get it sorted but I'd definitely press them a bit on giving you credit for the driveshaft. Sadly, the squeaky wheel gets the grease.. just how things are at times sadly.
Man, I'm trying to be haha. I know KPower is pretty esteemed around here and their customer service has been good so far. Don't wanna badmouth anybody or make enemies just because I'm angry in the moment. I also have no experience with drivetrain swaps like this, and no baseline for how much should be expected to go smoothly or not. My estimate is that it's extremely variable due to all the factors involved lol. To top it off, it's not KPower's shaft, but another company's, whose name I'm not aware of. It's all good. I'm stoked to have Drivelines make me a custom shaft for this thing. I knew at some point I wanted something lighter anyways. Also, now I'll be able to brag that my driveshaft was made by the same people who made BJ Baldwin and Ken Block's vehicles to a bunch of people who don't care. Nothing but wins over here!
Bonus post. Ricardo messaged me this morning telling me that his 6 speed actually turned out to be an NB1 (no VIN tag on it) and the late-model 6 speed tailshaft I sent him wasn't going to work. I tore the tail off of my recently-failed early-VIN 6 speed and got it shipped out to him. See anything wrong here?
Got the new driveshaft today and put it in the car. The resonant frequency of the vibration moved up from 60mph to 75, and the location now seems localized to the rear end rather than the entire underside of the vehicle. Better than before, but still totally untrackable and still a bummer.
I’m gonna get the car in a lift tomorrow and stethoscope the rear end at 75mph. I can still swap in my old stub-type axles if the exhaust will allow it, and may try ditching the PPF delete brace and mounting my PPF to the transmission crossmember like SixShooter did.
Damn, that's a bummer that it didn't completely fix the issue. At least there's one less culprit now, or at least I'd hope so with how nice that driveshaft is.
Any idea what the weight savings are on the driveshaft compared to the K power one?
04-14-2024, 10:42 PM
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