Vibration Between 2500-3400 rpms. What can this be?

[Mattr89]

So if I am in any gear I get this vibration around 2500rpms and stays until 3500rpms.

It just started appearing in the last 6 months or 1500 miles.

It feels like a massager or vibrator pulses trough the engine and floorboards. No clunking or out of the ordinary sounds. Just feels like engine vibes through the car and enough the I can hear it rattling things on the dash board.

So I did the following:

all new tires roadforced on a hunter balancer @ less than 10lbs of roadforce.

I unbolted the subframe and supported the engine on a jack stand and moved subframe around to make sure it wasn't binding.

Checked mounts and they are good. I replaced the outer tie rod ball joints. I also installed maximum Motorsport camber/caster plates.

Alignment is spot on. The only thing I can think of is the h pipe hangers and mounts could be binding, or the BMR lca and UCA?

Mods:

New plugs ford racing HT0
New 40,000 bolt coil packs
JBA off road H pipe
JBA Longtube headers
Driveshaft shop aluminum driveshaft
BMR relocation brackets (bolt on)
BMW Lca's with poly bushings
BMR adjustable panhard bar
BMR UCA (old version, non adjustable)
Eibach pro kit
Bilstein HD struts and shocks

I was thinking about going back to stock Lca's and UCA to ensure less tension and for more soft feel, would this help?

I had the Lca's bolted to the top hole on the relocation brackets, I moved it to the center hold and it's a bit smoother but not much.

I might cut the h pipe hangers just don't want it to fall.

Any help would be greatly appreciated. Thanks!

Spark plugs gapped at 0.45. Supercharged with 3.4 pulley.

 

[Dubstep Shep]

You can rule out everything suspension wise if the vibrations are independent of road speed.

If they're related to road speed, it's likely something with the balance of the wheels or so forth.

 

[Fullboogie]

Do not overlook the H pipe hangers, particularly the driver's side which will vibrate on the tranny crossmember.

 

[07graygt]

Drive line? Maybe threw a weight or someone added weight? When I used to work at the tire shop we would mess around an put tape a weight on guys cars/trucks makes a good vibration.

 

[Mattr89]

Around 1500-1900 rpms I feel the car wobble in neutral.

It feels like someone on either side of the car pushing lightly then vibes turn to a massage type pulse around 2500.


At 1800 it seems the vibe pulses are more spaced out not like a vibrator massage almost car with slight shake. Like weak mounts.

 

[Dubstep Shep]

So it's completely unrelated to the speed of the car?

 

[Mattr89]

So it's completely unrelated to the speed of the car?

Yes but seems slightly more prominent while in gear due to the load through the drivetrain.

I have no vibes that I can tell outside the engine vibes. In neutral revving it's almost the same.

Road forced all 4 wheels.

7 lbs force on passenger front
11 lbs driver front
14 driver rear
15 passenger rear

Alignment spot on.

 

[avinaj80]

Are you manual trans? If so, i had a similar issue that turned out to be this:
(pulled from my own vibration thread)

Looks like your first suspicion was correct. I've been sitting on a replacement clutch for about a year and a half and 37k miles ago. Stock clutch finally replaced at 138,567 miles and looky the disk.

Shitty cell phone pic, but yeah. One side of the linings just completely sheared off of the center plate. Pressure plate had some fingers loose also.

I still give it up to the factory unit. Couldn't of asked for anything more from it. I did replace it with another stock unit also.

 

[Mattr89]

Are you manual trans? If so, i had a similar issue that turned out to be this:
(pulled from my own vibration thread)

I have a Manual trans. Replaced the clutch with exedy Mach 500 and exedy steel flywheel, new throw out bearing. New clutch setup has about 15k on it.

 

[avinaj80]

Stock balancer or UDP?

 

[Mattr89]

Stock balancer or UDP?

Yep. All factory pulleys. Supercharger too.

 

[1bad99]

I noticed you said aluminum drive shaft might need high speed rebalanced I had same issues but mine is a home made shaft sent it in to get balanced and no issues now

 

[Mattr89]

I noticed you said aluminum drive shaft might need high speed rebalanced I had same issues but mine is a home made shaft sent it in to get balanced and no issues now

This won't affect vibes while in neutral will it?

Also when I put the car I to second to downshift while coming to a stop sign or light if I got into first I can hear harmonics or a whine. Local shop said that is normal for 1 piece shaft. Is this correct?

 

[eighty6gt]

It's normal to hear synchronizer noise downshifting while coasting to a light, especially in 1st.

How many miles on the car? The engine mounts could be giving up. I have steeda urethane mounts.

.045 is a very big gap, I'd put that at .035, even if it is a low boost setup. How old are the plugs?

 

[Mattr89]

It's normal to hear synchronizer noise downshifting while coasting to a light, especially in 1st.

How many miles on the car? The engine mounts could be giving up. I have steeda urethane mounts.

.045 is a very big gap, I'd put that at .035, even if it is a low boost setup. How old are the plugs?

Plus and coils have less than 1k on them. I have high voltage coils. Big gap means more spark demand. Factory coils are 20k volts mine are 40k.

How can I be sure if the mounds have given up?

 

[eighty6gt]

Who made the coils? Have you still got your factory coils and did they work?

 

[Mattr89]

Who made the coils? Have you still got your factory coils and did they work?

They are granatelli. Many have had problems with them, but I figured out why. My mustang doesnt misfire either.

The factory ones were old with over 110k on them.

 

[eighty6gt]

Put me in your shoes I'd do something cheap and lower the gap to .035". After that I'd go searching for a set of new OEM coils. How'd you fix the terrible Granatelli units?

With that many miles maybe after trying plug gap do the engine mounts, they are inexpensive and I really liked the way they felt. The stock mounts are very, very soft. I bought mine from Steeda.

 

[Mattr89]

Put me in your shoes I'd do something cheap and lower the gap to .035". After that I'd go searching for a set of new OEM coils. How'd you fix the terrible Granatelli units?

With that many miles maybe after trying plug gap do the engine mounts, they are inexpensive and I really liked the way they felt. The stock mounts are very, very soft. I bought mine from Steeda.

Could this be a symptom of the oem mounts going bad?

Also I believe the vibrations started after swapping long tube headers.

Could it be the tune? I was dyno tuned with a set of headers and then changed them.

I now have JBA. The headers prior were replicas and almost identical in every way.

Jim over at Jdm Motorsports said he didn't think I would need to retune

 

[eighty6gt]

Probably don't need to retune but you can almost be sure the new headers are touching! Have a look. I think you've found your problem, those are the rpm ranges that things would buzz.