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Copy that, man. Sounds good. Dunno how far from their HQ you are but I assumed it'd probably be in your hands next week based on my call with Jamie.
Makes sense about having your local shop inspect it first. Hopefully the new supplier is better than the old one.
At any rate, keep us posted. I'm distracting myself right now with a digital dash build but am still on the edge of my seat hoping it fixes your car.
If I’m understanding them correctly, it sounds like it’s the same supplier having a go at making the aluminum shaft. I’m def a test case, as they do not have a car to put it in… not ideal. This is what is driving me to have the shop inspect it.
question is, if they find issues (I bet the u joints are not preloaded enough like the past ones) do I have them fix or just run it as-is?
Maybe a bit unrelated as i run a different transmission and a normal yoke/driveshaft but maybe my 2 cents are worth something.. So i just got done with a tremec TKX swap into my NA still running a turbo 1.6 and a 1.8 torsen and fighting the same issues it seems... First driveshaft i got made from a local place same 70ish mph i get a decently high frequency vibration that doesn't seem to subside just gets worse it feels like i got the car up to around 95 about all i wanted to do. Checked pinion angles and all that i could they are damn near perfect at the moment actually zero degrees difference in them both... Talked to the driveshaft company they looked it over today and ended up re tubing it as they found a little spot they didn't like got it in and it made ZERO difference what so ever. Good to know it’s in better shape(I hope, can’t fully trust it yet I guess) but i was hoping it would do some difference and maybe point me in the right direction. I ran the PPF to my crossmember and getting the weird vibration. I also put together this jank ppf delete thing that i ran originally and drove it a few times, i cant remember if the vibrations were there or not i dont think i ever got it up fast enough, that mount just sketched me out if it ever did fail but im thinking of trying it again just for the hell of it... I really dont want to go get yet another driveshaft made, really don't know what else to check. I have a ford 8.8 that needs rebuilt to swap in but was hoping i didn't have to spend all that money at the very moment on top of the already expensive tkx swap... i also ran into the thing of my diff fluid getting dirty extremely fast in under 70 miles it was pretty bad, i noticed it as i swapped to a spare torsen i had to see if it fixes the issue and it didnt. Im starting to think stock miata diffs in swaps are just cursed
Yep, poly on diff and suspension. I run a hybrid motor mount setup of one awr poly on one side and a mazda comp mount on the other but has never given me issues before, engine sits flat.
Ive swapped torsen's (old was type 2 one in car now is type1) although i never had the 1st diff fast enough to see tis vibration i was troubleshooting a decel noise that ended up just being from a lightweight flywheel and transmission chatter i think and hope... had a brief thought of throwing in an open diff ive had sitting around for a while and just see what happens but i dont expect much would happen tbh still deciding if i wana pull the diff yet again, all are 4.10 ratios.
If you tell me that you swapped to rubber bushings and the vibration went away, I'm literally going to kill myself.
Lol in all seriousness, I'm not sure if I'm glad or bummed that even more people are having the same issue even with different trans setups. @Kanaan what's the weight on your driveshaft? Based on everything I've gone through so far, another theory I have is that the Miata diff/pinion doesn't like having the force of a 2x+ heavier than stock driveshaft exerted on it. Our diffs seem to be doing the exact same thing, my two week old diff fluid came out really dark again when I drained it last week. If you put the car up on jacks and get it into the vibe zone, does it feel like the vibration is resonating from the diff? My guess would be yes just like mine.
I just broke my diff arm (my fault, KPower said to reinforce it if you're running a PPF delete brace and I missed that bit of literature) and will be replacing the housing this weekend. Interested to see what the diff looks like and will post updates here.
If you tell me that you swapped to rubber bushings and the vibration went away, I'm literally going to kill myself.
Lol in all seriousness, I'm not sure if I'm glad or bummed that even more people are having the same issue even with different trans setups. @Kanaan what's the weight on your driveshaft? Based on everything I've gone through so far, another theory I have is that the Miata diff/pinion doesn't like having the force of a 2x+ heavier than stock driveshaft exerted on it. Our diffs seem to be doing the exact same thing, my two week old diff fluid came out really dark again when I drained it last week. If you put the car up on jacks and get it into the vibe zone, does it feel like the vibration is resonating from the diff? My guess would be yes just like mine.
I just broke my diff arm (my fault, KPower said to reinforce it if you're running a PPF delete brace and I missed that bit of literature) and will be replacing the housing this weekend. Interested to see what the diff looks like and will post updates here.
I never weighed it but it is certainly a good bit heavier over the stock one. Honestly i never pinpointed exactly what was vibrating but yeah id say its around the diff area as far as i can tell. I need to have someone run it up to that zone so i can get under there and feel around. Also Id just have to re-seal it but i have my old torsen sitting in a housing that still has stock rubber bushings in it, might eventually be worth a try i suppose if the poly ones are a suspect.
I’d be very interested to see if stock diff mounts with a PPF are a recipe for success
I should have some time later tonight to mess with it. Id hate to do more than one change at a time but since its mostly ready to just go in and to save swapping the diff multiple more times for other possible changes I might put my open diff that also still has stock rubber bushings in it tonight and if for some reason that does fix it i can narrow down which one did it from there. Ill make sure to post back what i find
Well maybe tonight.. Looking into it a bit i dont know if i have the stock plates with the spiky rubber things on it anymore
EDIT: This may have helped some i cant fully tell yet as now i have more of a thumping sound at low throttle/speed which very well could indicate i now have a pinion angle issue, i worked on it for so many hours last night experimenting i cant remember where/what angles i left it at before i went to bed or its that loosening those nuts let the diff go up a bit if it was in a bind throwing my angles off.
original message:
Maybe everyone already does this an im just jumping the gun thinking i found something but i cant find a single bit of info regarding this procedure, these support plate things on the bottom of the diff mounts well on a stock car the diff typically is flat with the car and is kinda where it rests bolting it up as the miata drivetrain is basically flat.. In my case atleast and presuming most swaps it gets angled up to fix pinion angles mine for example is like 2.5 or something deg but idk if these support plate nuts ever get backed back off to relieve any binding thats there since those plates hold that big stud solid to the subframe so 100% of that 2.5-8 degrees comes from bushing squish/deflection, and with poly bushings thats one hell of a bind maybe making it a sort of rubberbanding/vibration at a certain speed? looks like people online seem to think these plates just hold the bushings in which i dont think is really the case. This would make sense as to why greg's car magically is fixed after a diff swap that doesn't even utilize any of this stuff at all and braced entirely different. The passenger side supporting plate studs on my car are snapped off and have been for as long as ive had the car so only the driver side was snugged down but i think you get the picture.
Bummer on the stock plates/rubber mounts missing. Keep us posted still.
It's strange to me that binding/motion in the mounts would cause a vibration at a certain speed rather than a certain amount of load applied. You're going to get the most deflection in the bushings/mounts when the drivetrain is under heavy load and during peak torque, right? I'm sure there are additional factors at play, though. Again, maybe the stock diff/mounting setup just has some sort of issue with a substantially heavier driveshaft spinning at 4.5krpm. I mean look at the paper thin Miata pinion flange compared to the Getrag or Ford 8.8.
Bummer on the stock plates/rubber mounts missing. Keep us posted still.
It's strange to me that binding/motion in the mounts would cause a vibration at a certain speed rather than a certain amount of load applied. You're going to get the most deflection in the bushings/mounts when the drivetrain is under heavy load and during peak torque, right? I'm sure there are additional factors at play, though. Again, maybe the stock diff/mounting setup just has some sort of issue with a substantially heavier driveshaft spinning at 4.5krpm. I mean look at the paper thin Miata pinion flange compared to the Getrag or Ford 8.8.
Ok that's enough speculation from me.
Do you still run that cast iron pinion weight balance deal? i forgot the name for it but i was debating cutting mine off but i dont think its an issue mines still pretty solid to the shaft. If anything its a couple pounds of weight off the diff.
And yeah all the speculating is hurting my brain too, the rubber plate things i have to have some but i cant say i ever kept up with where they went.
I do still have the balances on my diff flange. I remember Curly saying in another forum that people have chopped them off with no ill effects. No firsthand information on them affecting the vibration we're having though.
I do still have the balances on my diff flange. I remember Curly saying in another forum that people have chopped them off with no ill effects. No firsthand information on them affecting the vibration we're having though.
so my above comment sounded kinda dumb but I believe it did help, Hopefully its not all in my head but it still has a bit of something come on around that speed i dont think its as violent. Without touching anything all I did was loosen those 2 12mm and the diff tilted forward like a .5-1 degree
or so and threw my pinion angle off that much. So that means I had my ppf shimmed way too far up and all that was extra compression on those bushings that I didn’t need and maybe ppf flexing a hair? Idk where the extra angle would have came from if it wasn’t.. Went for a drive and while my cars no Cadillac I think it’s a little better, I’m going to have to draw a line somewhere because this cars basically all poly bushings and mostly spend 225 old 200tw tires it’s never gona be perfect I could chase my tail for ever here. I got it up to 95 and while it was decently buzzy idk if it was any worse than It was with the old 5 speed I honestly can’t remember it’s been like 6months. Next step just to verify is do what you said and run it up and feel the diff or something. And I only have these on one side the other sides broken off. Can’t say it’ll fix your problem but It’s worth a shot if anything. If anything its less stress on the diff arms in a twisting motion
so my above comment sounded kinda dumb but I believe it did help, Hopefully its not all in my head but it still has a bit of something come on around that speed i dont think its as violent. Without touching anything all I did was loosen those 2 12mm and the diff tilted forward like a .5-1 degree
or so and threw my pinion angle off that much. So that means I had my ppf shimmed way too far up and all that was extra compression on those bushings that I didn’t need and maybe ppf flexing a hair? Idk where the extra angle would have came from if it wasn’t.. Went for a drive and while my cars no Cadillac I think it’s a little better, I’m going to have to draw a line somewhere because this cars basically all poly bushings and mostly spend 225 old 200tw tires it’s never gona be perfect I could chase my tail for ever here. I got it up to 95 and while it was decently buzzy idk if it was any worse than It was with the old 5 speed I honestly can’t remember it’s been like 6months. Next step just to verify is do what you said and run it up and feel the diff or something. And I only have these on one side the other sides broken off. Can’t say it’ll fix your problem but It’s worth a shot if anything. If anything its less stress on the diff arms in a twisting motion
Interesting there. Glad you were able to make an improvement by doing that. So the vibration comes on at the same speed just lessened severity? That’s what I felt after shifting my subframe over a tad. How bad is the vibration now? On Rich’s and my cars, it’s bad enough that it feels like it’s gonna damage something. Just trying to gauge how similar our issues are.
I gotta swap my diff housing this weekend. I’ll check if anything seems to be bound up when I remove it.
Originally Posted by sixshooter
I'm still using the stock 1996 original diff mount bushings, lol. Never changed them.
This has to be the last difference between our setups that I haven’t verified haha. Maybe I’ll grab a set of rubber bushings and see if that makes a difference.
kpower requires poly bushings with the PPF delete- still twisting my brain that we’re having issues after “hundreds of kits sold”
I actually went through some lengths to make sure I was not preloading or binding the diff bushings when installing the K power diff crossmember. I put my jack under the diff to provide upward pressure and then tightened up both mounts and retention plates. Once it’s all tightened up, there is not much/any play in the diff assembly.
I found the crossmember mounting tab holes were a bit low to capture the bushing, so I had to slot the holes about 2mm (up) so I wasn’t pulling the nose of the diff down and preloading the bushings. (I’ll snag a pic here if that didn’t make sense)
but yeah if the alloy shaft does not fix, then I think that is the next thing I will try (stock or mazdaspeed diff mounts & ppf)
I didn’t really like the nvh that the poly mounts added anyways!
05-02-2024, 07:06 PM
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