Drive train vibration

[Voltaire]

I recently re-built and installed a ford 302 in my cobra as well as a new Center Force dual friction clutch, throw out bearing and input shaft bearing. The issue I am having is a vibration that starts around 3800 rpm (not very noticeable) and gets increasingly worse as I go up to 6300 rpm or hit the rev limiter. This is under load running through all of the gears. If the car is neutral and I rev it up there is no vibration. Any thoughts on what could cause this would be appreciated. The vibration isn't horrible but it is annoying.

Drive train details;
Boss Block 302 block, Probe mini dome pistons, Eagle H Beam Rods, Forged steel crank, 50oz balancer, Trickflow track heat heads and intake, Trickflow stage 2 billet cam

Transmission/Rear End;
Centerforce duel friction clutch and clutch disk, billet fly wheel, Lakewood scatter shield, TKO 600, aluminum drive shaft, Strange Engineering aluminum 9” center section 3.73 limited slip

[blykins]

First thing that comes to my mind if you don't get an engine vibration in neutral, would be to check the u-joints and make sure the pinion nut is tight.

Also, I assume the driveshaft has been balanced.

[Jerry Clayton]

Is the flywheel 50 oz balance also??

Are the u-joints timed correctly??and u-joint/pinion angle thru out opt suspension travel??

[Wbulk]

You don't say if the car has been run before with another engine. If it has then the problem would be with this engine/flywheel. If not, then it could be engine/flywheel, trans bearings, u-joints, rear axle pinion angle off. If it's solely based on RPMs and not speed, then that eliminates a lot towards the rear.

[xlr8or]

Did the bellhousing get indexed to the block?

[bobcowan]

Since it's there in all gears, it most likely not the trans, drive shaft, differential, tires, or suspension.

Did you put the dowel pins in the flywheel to locate the pressure plate?

Many billit flywheels have a removable weight, so you can use a 28oz, 50oz, or no weight at all. Did you check to make sure it matches with the rest of the engine?

[CobraEd]

Is the crank from a "302" or a newer "5.0". The engine balance is different.

A 302 need 28 oz on the harmonic dampner AND flywheel. The newer 5.0 needs 50 oz on both.

If the engine is smooth in neutral and the vibration only occurs when driving, then it is driveshaft balance (or lack there of) or bad U joints or wrong pinion angle.


.

[FWB]

sometimes the force put on the trans mount by letting the trans hang or changing stuff around weakens it and can give you vibes......

[tcrist]

When you are driving and you have the vibration, kick it out of gear and let the engine drop down to idle and see if the vibration is still there. Basically, try to eliminate your drive-train and isolate it to your engine clutch area.

If you have driven it before with a different engine and no vibration, then changed engines and have a vibration, then you pretty much know where to look.

Did you put in the correct pilot bearing?

Is the pilot shaft now too long and bottoming out on the crank (because of a different crank)?

Did you align your bell housing using a dial indicator or just bolt it in?

Any minor imbalance in your engine will transfer the vibration to the seat of your pants.


Just a few thoughts.

[Voltaire]

The car previously had a 302 roller in the same configuration. The bell housing, transmission, ujoints, drive shaft and rearend have not changed and there was no vibration previously. When I changed the engine I went to the new clutch. I reused the flywheel (after having it resurfaced). The input bearing is new and is the right size. The throwout bearing is also new. The harmonic balancer is a new one. The rotating assembly was balanced with flywheel and harmonic balancer at a builder here in phx. I just bolted the bell housing up as the bell housing were never removed from the car. Before pulling the transmission I will try some of the other easy suggestions to try and identify the problem. I need to see if the harmonic balance has gone bad, I believe this can be checked by checking timing.

[CobraEd]

if the old engine was a roller, then it was a 5.0 not a 302 per se. It had a 50 oz balance on the front dampner and rear flywheel. If the engine now is a 302, (non roller engine), it needs a 28 oz balance at both ends.

When the guy balanced the rotating assembly, he had no issues ????
.

[Rick Parker]

Your balancer and flywheel are different imbalance weights.