I'm getting a nasty vibration in the steering wheel, it seems worse at 30mph. This happens at any rpm. What could it be?

 

I would first rotate the wheels/tires, front to back and back to front and see if any change.

 

I think you nailed it. This happened shortly after I had the tires rotated at Firestone. I'm not sure if it was immediately after, I would have brought it back. I remember thinking that the vibration was caused by some unevenness caused by the rotation and that it would go away after driving it for a while, it didn't. I eventually took it back to Firestone and they wanted to "charge me to diagnose the issue" I explained that this vibration occurred right after the rotation but they wanted to charge for the diagnosis anyway. A lot of time has gone by since I had the tires rotated but not many miles, I don't drive it much. In my search for the causes of the vibration, everything points toward a tire issue. I do park it for extended periods of time and that can cause flat spots but it never has before. These tires were new from firestone and come with free rotation for life. This was the first rotation. Should I pay for the diagnosis? Should I take it to another firestone? What should I say to them?

 

Sounds like you know the answer and need them to buy in.

If you have lifetime rotations, take it in and have them rotate it, and if it continues, take it back immediately and explain the vibration is still present after they did work. This sounds like it is 100% obligation to check the work they did.

 

The rotations are every 5000 miles. So it will be quite a while before the next rotation. They made it real clear they didn't want to touch the car without charging a fee to "diagnose" the issue. Maybe that's the answer but it doesn't' seem right given the circumstances. So I'm wondering what else could cause these vibrations? What could they find that wouldn't be caused by the rotation? One of the other things I found on the internet that would cause this is a missing balance weight or an improper balance. Does that sound plausible?

It might be worth mentioning that when I brought the car in to have the tiers rotated they tried to charge me to do it. I told them it was part of the warranty, required and lifetime rotations were included with the price of the tire. They asked me if I bought the tires at that store which I did. So they did the rotation without charging me for it but they were not happy about it. My records come up with my phone number in their system so they literally had this information in front of them at the time but they asked me to pay for it before I objected.

 

if you feel it in the steering wheel then it is 100% tires/wheels related. quite possibly a ripped cord in one of your tires, you should get them checked before complete tire failure, for your safety. a ripped cord is serious and potentially can cause the tire to rupture and lose control being a steer tire.

this is a warranty-able condition if it is a broken cord so get it done sooner than later.

they may want a diagnosis fee, but it should be waived if the tire is faulty and under warranty. check your warranty sheet/store warranty information for further details whether or not the warranty covers diagnostic costs and for how long the warranty on the tires is for.

if it is "flat spots" from sitting, that may not be covered and is an irreversible condition. raising the car and running your hand over the tread while rolling the tire should easily tell if it is a ripped cord though, you will feel a bubble in the tread that usually covers 1/4 of the circumference.

 

I called Firestone and spoke with a different person. They said they could look at the tires for free in a couple of hours from now. I drove there but all they did was take the tire pressure, measure the tread and try to sell me services. They said it might be a wheel balance issue and asked me to pay for that. Yes, it is possible that it’s a balance issue but what if it isn’t, I don’t want to pay that if it’s not the cause if the vibration. They gave me an estimate for $70.90 to balance all four tires. Explaining a lifetime balance is also available but that would only be for those tires, not the car. They also explained that because the tire is almost 4 years old they couldn’t replace it without charging me full price for each tire.

I asked how long the warrantee was on the balance and was told 10,000 miles. So we looked up my records and found there was just a little over 5000 miles on these tires. So I asked them to honor the warrantee and balance the tires but they refused. We went round and round for a bit and they agreed to rotate the tiers again at no charge. I have an appointment for Monday. So they will rotate the tires but they won’t check them to see if they are damaged, weird. Can I trust these people to do anything to my car?

I did the math on the tires:
Tiers Installed ~ 2021~11NOV~19th ~ Mileage = 188,975
Tires Rotated ~ 2024~10OCT~08th ~ Mileage = 194,107
Total Miles ~ 2025~09SEP~11th = 5,132

I looked up the warrantee information for the tires:
The Basic Limited Warranty covers all tires in the following brands: Primewell A tire covered by the Basic Limited Warranty will be replaced with an equivalent new tire for a pro-rated purchase price if it becomes unusable for any reason within the manufacturer’s control under the following conditions:

There is no free replacement period. Coverage extends up to 4 years from the date of purchase – proof of purchase date required. Without proof of purchase date, then 5 years from the date of tire manufacture. During this period, the tire will be replaced charging a prorated amount. To determine the replacement price, the percent of worn tread is multiplied by THE RETAILER’S selling price for the replacement tire(s) at the time of the warranty transaction. The appropriate taxes, mounting, balancing, disposal fees, and other service charges may be added to the replacement price. The tire must not be worn to 2/32 inch (1.6 mm) or less remaining original tread depth (i.e. worn down to the top of the built-in indicators in the tread grooves). Exclusions apply as identified in the Warranty Manual.”

I looked up the warrantee information for tire balancing:
At Firestone Complete Auto Care, the warranty for tire balancing depends on whether you purchase a one-time service or a special lifetime plan. Standard tire balancing: If you pay for a single tire balancing service, it is covered by Firestone's nationwide service warranty for 12 months or 12,000 miles, whichever comes first.

Lifetime Wheel Balance plan: For a one-time fee, you can purchase the Lifetime Wheel Balance plan, which covers the service for as long as you own the vehicle. What it includes: Under this plan, Firestone will balance the tires and add external wheel weights whenever needed for as long as you own the vehicle and the originally balanced tires remain on the wheels. Conditions: The warranty on this plan is valid only as long as the original tires are still on the wheels. Additionally, any charges for resetting the Tire Pressure Monitoring System (TPMS) are not included.

 

tire shops are pretty bad about diagnosing anything. they're filled with teenagers who know less than your average newb to this forum unfortunately. all they need to do is jack the car up and turn the wheel and feel/look at the tire tire for flatness. this can also be seen on a tire balancer and would really show up on a tire balancer that does road force measurements.

sounds like your warranty period is up regardless so you may want to try a different tire store with a better attitude about trying to figure out if its a single tire issue or multiples.

 

Might even be a bent wheel which could be checked by jacking up the car, lay a piece of wood
on the groundon side of tire, and lay maybe a screwdriver on the wood with the blade against
the wheel, spin and see of the wheel moves against and away from the screwdriver.
Same can be done to check tire. Wood on ground in front of tire, spin and see if tread moves
in/out from the wood.

 

I took the car to Firestone to rotate the tires. The manager tried to give me a 5gal bucket of car wash things for free but I gave it back. They said there were going to balance the tires and he was informed of the situation. I watched as they checked for defects in the tires. They think the passenger front bearing might be loose. They called me over to look at it and asked if I still wanted the tires rotated. I said yes because I had spoken with the people who rebuilt the engine and they said to have the tires rotated, see what happens and and bring the car to them if the vibration doesn't go away.

Firestone did the rotation, balancing and a road force test. The front right tire was off by 1.2 oz and the driver’s side rear tire was also off by ??? Maybe this was caused by the tire being off balance. They said the road force test was very good for cheap tires. They put the tires back on the car and gave me the key.

On the way home I discovered the car still vibrates but now it vibrates differently and the vibration is a lot quieter. I get different vibrations at different speeds. The vibration still happens at zero RPM in neutral. I can now hear a new vibration when pressing on the gas pedal but it’s a different kind of vibration and not always present. Maybe there’s more than one issue. Or is all this vibration coming from the bearing?

When I got home and checked email, the Firestone receipt just said "TIRE ROTATION - WARRANTY N/C". There was no charge for anything.

 

i assume the vibration can't be felt in the steering wheel anymore?

 

It can be felt in the steering wheel, not only felt but you can see it vibrating up and down, maybe about an inch or so at its worst. Changing speed produces differint amounts and kinds of vibrations.

 

oh i see, i don't typically relate steering wheel vibrations like that, i meant if the wheel feels wobbly in your hands like it's turning itself left and right on it's own in small oscillations. if it is a whole car vibration it could be something like a u-joint failing in your driveshaft or the shaft being out of balance, or something that attached itself to a half shaft in the rear of the car.

but you said it changed with the tire rotation and balance. i'm still wondering if their machine is miscalibrated. it's possible it had a balance issue and a 2nd primary vibration that still is unresolved.

they didn't give you any road force numbers either, do you have a printout with those numbers? they should be in lbs not ounces, ounces are the weights needed to balance the tire. pounds would be the force the tire exerts against the road surface, these small tires should only be a few pounds on a road force. something like 15 lbs would show up as a vibration to the vehicle. 13 pounds on a road force is typically the limit for any wheel/tire assembly.

 

The vibration was mostly up and down now it's a lot less but still there. I drove it a bit today just to listen to the vibrations and to be more accurate about what triggers them. Pressing on the gas pedal does cause a vibration intermittently and at certain speeds. It goes away when I push the clutch pedal down, When I roll it down a hill in neutral it will vibrate at a differint rate. So there are three ways to change the vibration. I don't know enough about cars to know what to listen for or how to test it properly.

I would assume machines like the tire balance must be calibrated regularly or just work properly.

When I got home and checked email, the Firestone receipt said TIRE ROTATION - WARRANTY N/C. There was no mention of the road force test, the balancing or the corresponding numbers. Since I didn’t pay for these things I didn’t contact them to ask for a receipt that documented what actually happened. Driving home I was really surprised the vibration was still there and discovering the new way to cause some vibration was very disappointing because I was sure it was just the bearing at that point. Now I don't know what it is or if there's more than one issue.

 

if you're not mechanically inclined, vibrations can be one of the more difficult issues to diagnose on a car. there is very specialized tools to measure the hertz of a vibration and chassis ears to listen for the peak noise location. but personally i would start by checking engine, trans and differential mounts. a simple blown shock can cause a vibration as well.

 

I brought the car to local auto repair place and they determined the vibration is being caused by bad U-Joints on both ends of the driveshaft. They needed a couple of days to do some research to determine weather or not they could fix it and they just called to tell me they can't. This is very strange to me because when I got home I did some research on the repair and I was able to find several places that sold the U-Joints and a couple of places that sold the driveshaft itself with the U-Joints attached. I even found a couple of websites with step by step directions of how to do it. I don't have the tools or experience to fix this. So I called a bunch of local repair shops and they all say they can't do it either. I just found the sticky list { NW List: Motor Rebuilders, Tuners, Rotary Specialists, Performance Parts } so I'll start looking for someplace on it.

 

you can call a driveshaft repair shop locally and ask them. the FC uses staked in u-joints so technically it is considered to be a non servicable driveshaft but it can be modified to accept replaceable u joints.

it's an inevitable issue we all deal with, since there is no grease fittings on the joints either.

 

I had no idea driveshaft repair was a specialty that existed. I found one on 4th Ave South, just past Costco in Seattle here. Their website only mentions the manufacture of the driveshaft but not the installation. O'ReillyAuto and Mazdatrix have replacement driveshafts with "serviceable" U-Joints. I found Instructions to replace the driveshaft and Instructions to replace the "non-replaceable U-Joints" and another one here. Obviously I would rather replace the U-Joints and not the whole driveshaft but I'm not sure I can do that or if I can find someone willing do it instead of replacing the whole driveshaft. I did find replacement U-Joints that are greaseable but can I use them?

 

The joints are not serviceable iirc. If your joints are shot then you need to replace the whole driveshaft, or make one. It will probably be the same price either way you go.

 

yeah, driveshaft repair and manufacturing is a common service in most areas. those shops rarely do actual vehicle repair though so you'd have to have a shop remove yours so you could have it repaired or remove it yourself, it is a rather easy job to do.

i have had these types of shops repair FC3S shafts before. i built one car that made 500RWHP that twisted a shaft and lost balance that caused a vibration like you describe, a driveline shop was able to repair and rebalance it. about 15 years ago i think the service was around $100, probably around $250 now for new u-joints and this modification.

it would likely save you a considerable amount having it taken in for repair over buying a whole new shaft. though the aftermarket ones are certainly viable options, i figured they would be over $500 by now. it is a job someone motivated and who has a grinder and press could do at home to save a bit more, but you have to feel comfortable with modifying parts before you even attempt to tackle a job like this.

 

I'm not sure if this is the original driveshaft. Some aftermarket driveshafts are made to have replaceable U-Joints. Can you tell by the pictures if these U-Joints are replaceable? I'm not sure but the drive shaft itself seems to be missing a chunk of metal right where it connects to the U-Joint. Does it look like it's damaged? And there seems to be a bit of liquid coming out of that thing sticking out, what is that?

The Back U-Joint

The Front U-Joint

 

that's a stock shaft with staked joints. technically called a non serviceable shaft, but anything is serviceable with the right amount of effort. a driveshaft repair shop can rebuild it, or follow the DIY replacement instructions which requires a heavy press, some heat and grinding.

 

So it will be the more difficult to remove and replace method if we keep this driveshaft. What determines the "serviceability" of the driveshaft, the shape of the driveshaft or the type of U-joint used? Can a NON-Serviceable driveshaft be converted to a serviceable driveshaft by using differint U-Joints? Are these the correct replacement U-Joints ?

 

I looked into replacing the staked-in universal joints on my FD since the originals felt a little notchy, and it looked like more than I was willing to take on myself. Here's a video I found, it's not an RX7 but the driveshaft looks similar:

 

the joint dimensions on that joint match the rockford 430-10A so it should fit, for anyone else, be aware the TII shaft has a bigger u joint and this one isn't for you.

this process removes the stakings holding the stock joints into the shaft and replaces them with an inner circlip to hold the joints in place, making the joints replaceable. the new joints have grease fittings too, so you can lubricate them unlike the stock joints which are serviced for life with no grease fittings.