Vibrations Part 2
 

1990 RX-7 Non-Turbo.

So recently, after I put some aftermarket wheels (17x9 Mbbattles, 235F, 255R; in case this may help) on my car, I have been getting violent vibrating ONLY while in gear/throttle. It coasts in neutral just fine. And this occurrence only happens on occasion -- and it nearly always happens when the ground is wet.

This vibrating literally shakes my shifter, the blinker and cruise control knobs, the steering wheel, and sometimes it feels like it is coming from more middle of the car and less towards the front. Other times more in the front. But it does not happen all the time which has been such a problem to diagnose.

Help please! The vibrations are driving me crazy.

Have you checked/replaced the motor and trans mounts?

at whats speeds? while turning, or just straight? hard on the throttle or even light? sounds like u joints in the drive shaft

It does not occur when I am turning and it is any time I am on the throttle -- when it does occur.

I have not checked the motor/trans mounts but I did not think these would be the issue. I will check them tomorrow as I work all day today. Any other ideas while I am investigating? I thought about the driveshaft being a possible problem.

driveshaft u joints

I will take a look at the mounts and driveshaft u-joints tomorrow and see if those are the issue. Thanks!

But he said it goes away when he takes it out've gear, if thats the case, the driveshaft is still turning due to the rear wheels turning, so if it was the ujoints, it should be giving the same symptoms whether in gear or not

Just check everything. Differential mounts, engine mounts, transmission mounts, drive shaft.

Alright so, I did not get a chance to get under my car because I was sick and lying in bed all day on my day off, but I did read some more and drive it around. After reading a ton of old forum posts from my phone while in bed, I have come to the conclusion that it must be the driveshaft based on the symptoms that I am having. I am going to go ahead and check before buying parts but now that I have driven the car and can actually hear the clunk, it sounds like it is coming right from where the driveshaft/trans area.


Now, my next move, instead of buying a mazdatrix na, is to buy a Turbo II driveshaft and go ahead and buy Turbo II half shafts, diff, trans and all the accessory parts preparing for my Turbo II swap. If I do this, will the s5 Turbo II transmission mount in my factory S5 non-turbo mounting location without modification of the mounts? And will it bolt up to my S5 Non-turbo engine? (assuming I have all the correct parts, turbo slave cyl, rod, pp, clutch)

While your at it, check out the front different mount

Not to be too much of a bore, but let's maybe consider that we might be seeing horses instead of zebras.

That sounds a lot like improperly torqued lug nuts (by a lot in this case, I mean it sounds not at all like a driveshaft for the reason mentioned above, and exactly like improperly torqued lug nuts). Adding to the theory is the fact that before your new wheels, everything was honky donky and after blinging things up a bit things are not, and I think the evidence strongly favors a wheel related issue. Assuming you properly torqued the lug nuts, mayhap the guy that sold you the wheels didn't, drove on them a bit, and embiggened the holes. It may be the wheels are simply trash and you got a bad deal.

Check the torque on the nuts. If it's good (spec is 80-120 as I recall), pull the wheels off one by one and inspect the relative to their associated nuts. Aftermarket wheels are almost always lug-centric, so you're looking to make sure the nuts are perfectly centered and seated in their holes (you'll have to be on the inside of the wheel to see this).

Additionally, offer the wheel up to the hub and verify the studs sre similarly centered. Mayhap the lug pattern is slightly off.

a bad driveshaft u joint should go away in neutral/coast though, no? i mean, you're not transferring any torque at those times.
regardless, it is peculiar that the issue presented itself immediately after installing the wheels. as mentioned, AM wheels are a conical lug bore, whereas oe are hubcentric with a ball seat lug. you must use conical lug nuts on an AM wheel to properly center it. however, this problem SHOULD be evident related to tire rotation/speed, as upposed to torque. something smells rotten in the state of denmark. regardless, as mentioned, do a thorough inspection of those new wheels/installation before anything. while you've got it jacked up, check everything else mentioned

My thoughts too as far as neutral. ^

yea it wouldn't vibrate through the shifter if there were no transfer to it. it really sounds like u joints. wakey wakey. slam some coldfx and get out there with the jack

Yeah, he did say from the shifter area. Isn't 120 ft lbs a little much? Don't we use 12 mm studs?
I guess you can just impact it,

I am about to go jack up the car and feel up the driveshaft and check mounts.

It was peculiar about the timing of the the wheels going on; I actually used factory mazda lugs and thought it was the lugs at first. I have new lugs and some hub centric rings that are about to go on (not sure if they help, but a guy recommended them at a local meet, as they worked for him, supposedly).

And I have been using an impact wrench to torque the wheels down. But I will inspect the inner side of the wheel while I am underneath the car.

I firmly believe it is the driveshaft though as now I am hearing a clunking noise when I accelerate. And the car also vibrates violently.. But it coasts just fine.

Thanks for the suggestions and advice. I will report back asap.

FSM says torque is 65-87 ft/lb.

Imagine a customer with center lock going 450ft lb with broken torque wrench. Good thing we had one that worked and would click. In going to bug my boss man for the $1300 SNAP ON one

So I checked everything. The tranmisssion and diff mounts were fine, the driveshaft wouldn't budge an inch and I put a lot of my weight into it. I even took a picture and maybe you can see something that I don't. It's dirty but no problems from my eye. The wheels looked a little scratched where the old lugs were but nothing detrimental. From the inside, the lug holes looked fine. I used an impact wrench to tighten the lugs. It's a 19.2 volt craftsman drill providing 125 lbs of torque.

Attachment 556136 Blurry and low quality, sorry.


My hub centric rings were here, so I decided to install those and the vibrating seemed to vanish.. for now. But we all know how rx7's can be. The clunking is still occurring when I accelerate which I think is the transmission.

So I guess I will still be swapping out my entire rear end/driveshaft/trans as I wanted to do it anyways, this just gives me a good excuse. I'll drive it in the next few days and let you guys know if the problem appears again.


Thank you so much for the help and advice thus far!

are you using conical lug nuts? or oem ball seat?

I was using the OEM lugs but now I am using some thinner spline lugs. They are described as tapered lug nuts.

yes, those are correct