Engine vibration at 2200 rpm

[209]

Hello all,
What does Roush do when their sbf engine developes a vibration? No, I haven't contacted them yet. At first this slight vibration was felt at 2200rpms in 5th gear about 55/58 mph. I thought it was chassis related until recently when it happens in all gears at 2200. My installer is still scratching his head. Yes it vibrates in neutral at 0mph too. There is none at 2150 and none at 2250. Anybody experience this anywhere? I received the car/engine trans new in July and now I've got 4600 miles. I guess you can say the vibration is a tad more than new. Cliff

[RANDY CARTER]

What type of motor mounts do you have? I had the same problem on my SPF and SB Roush engine and it turned out to be only the motor mounts. If you have the very hard neoprene mounts instead of the softer rubber mounts this could be your problem. Hopefully you don't have an engine problem and just don't drive at that RPM to eliminate the vibration.

[RICK LAKE]

209 cliff I am hoping for the best which is either a dampener on the front of the motor may have gone bad if it is a rubber one. If it's a ATI or fluid one I doubt this is the problem. This leaves the clutch assembly or fly wheel.
The next thing to do is make sure that the motor doesn't have a bad cylinder. pressure test and leak down. if every thing is on the money next is to pull the trans and run the motor without the clutch assembly on the back of the motor. If the vibration is gone, you have either a bad clutch assembly or there is a problem in the trans. Even through you have the trans in netural this doesn't mean there is not a problem with the inputshaft bearing or main shaft. What trans is in the car? Tremac t-5, 3550, TKO 500, Tko 600. There has been some problem with them. Do you learn any noise in the trans? If it is easy, drain the trans and see if there is any metal in the fluid or in the bottom drain plug. If none of this shows anything, your motor may be going sour. I hope not, this would be last thing to check. At this time I can't think of anything else, Cliff. Rick L. Cliff send me a P-M with a number to reach you at in the evening. I'm in NJ.

[209]

Hello Randy and Rick,
Apparently I ran out of time and have to write this all over again. I have the polyurethane mounts 'cause I was told to put them in over the rubbers. The front dampner I have no idea what I have. I do know I have the TKO500 5sp and no noise but I do occasionally have difficulties getting into reverse. I have faith in my installer and even though he's 6 hrs away, I will do whatever he suggests. Other than the vibe, the motor is strong. There's a reason why I went with Superperformance and Roush and this means I normally know squat! But, ask me a question about Bultaco Astros and Pursangs and I'm sure I can answer and repair those. As for a pm, Rick, give me a little time to learn how. Thanks for your answers and hopefully I can find my vibe problem. Cliff

[CHANMADD]

All engines have a harmonic imbalance at about that RPM.....1800-2400 roughly. This is normally cured by balncng the rotating asembly.
So it cold be the damper..or an out of balance flywheel or clutch disc. I have seen a nd repaired engines that have cracked Bellhosins because of this imbalance John

[PANAVIA]

I have 20$ on the dampener, and 10$ on the motor mounts.

[DSM351]

WOW 4600 mines already!!
How bad is it, mine has the exact same thing, 392 (351W), but no one else can feel it?


Does anyone know if those fluid or bearing dampeners work?

r

[llobon]

could be both dampner and or flywheel due to weights involved
5.0ho has a 50oz on both flywheel and dampner while earlier engines had a 28 oz
351w engines had a 28oz

[PANAVIA]

Balancing ---or a off balance pulley. . . . hmmm.

[CowtownCobra]

You need to contact Roush about this. You have a Dart block with no Ford OEM parts, so the balance could be 28oz or it could be zero. Only Roush knows for sure. You paid top dollar in part for that warranty, use it!

[209]

Thanks for all your replies and suggestions. Cliff

[GMSmith]

I too have the same vibration... Actually, there is even a subtle one at about 950rpm... then at 2200, in any gear or in neutral... Wasn't going to run it to 44 (the next harmonic) to see... I would wonder about the flywheel if many have the same spots... it statistically should vary if the flywheel or pressure plate were of issue... IMHO... the Damper, maybe... It's annoying to be sure.

SPF ... Tied to a Tremmech 600

[jhv48]

What brand clutch did they install? Centerforce?

My bet is on the clutch. Haven't heard of a roush vibration problem in years. They seem to know what they're doing most of the time. Needless to say, they will want you to eliminate the possibility of the tranny or clutch causing the vibration before they will step up.

[olddog]

With transmission in gear, clutch pushed in. and car stopped, rev engine and see if vibration is still there. If it is, it cannot be the clutch, as it is not turning.

There are two different off set balance options for the SBF - 28 & 50. Also some aftermarket builders internally balance the crank. Do you have the correct flywheel and harmonic balancer for your engine? Are you sure?

[jhv48]

Originally Posted by olddog

With transmission in gear, clutch pushed in. and car stopped, rev engine and see if vibration is still there. If it is, it cannot be the clutch, as it is not turning.

There are two different off set balance options for the SBF - 28 & 50. Also some aftermarket builders internally balance the crank. Do you have the correct flywheel and harmonic balancer for your engine? Are you sure?

I think you mean that it isn't the transmission, as the clutch pressure plate is bolted to the flywheel and thus is still turning even when the clutch pedal is depressed. Still could be a damaged pressure plate, and often is.

[Rick Parker]

If it is Centerforce, it could have lost one or more of the counterwights.

[olddog]

Originally Posted by jhv48

I think you mean that it isn't the transmission, as the clutch pressure plate is bolted to the flywheel and thus is still turning even when the clutch pedal is depressed. Still could be a damaged pressure plate, and often is.

No. The clutch splines slip over the transmission input shaft. When in a gear and car stopped the transmission output and input shaft are not turning, and therefore the clutch plate is not turning. The pressure plate is bolted to the flywheel and it is turning, but the clutch is not. Otherwise the clutch would not work and the car could never be stopped when in gear.

[jhv48]

Originally Posted by olddog

No. The clutch splines slip over the transmission input shaft. When in a gear and car stopped the transmission output and input shaft are not turning, and therefore the clutch plate is not turning. The pressure plate is bolted to the flywheel and it is turning, but the clutch is not. Otherwise the clutch would not work and the car could never be stopped when in gear.

.

I think if you re read what I wrote, that is exactly what I said. I never mentioned the disc. Pressure plates have been known to crack or throw a weight and cause just this type of vibration.

[Clois Harlan]

Just a thought here, I recently experienced the same situation at the track in my coupe. Checked all the above including having all my tires re-balanced...it turned out to be my rear u-joint bolts had managed to come loose a tiny bit. Three of the four bolts has loosened because I failed to recheck them after installing my TKO 600. Simple and cheap fix if you don't count all the extra steps I went through to get to the u-joints.

Clois

[Jaydee]

Years ago I had a similar problem. I found one piston was a different weight.
Has yours been doing it since new? Maybe the harmonic balancer has slipped around the shaft.
JD