Sorry to hear this!
You will get it straightened out afterwards though. I Would have liked to see Black Jack! Is Grover still around?
Black Jack: Vibration resolved in time for Foxtoberfest!
- Thread starter FastDriver
- Start date
You will get it straightened out afterwards though. I Would have liked to see Black Jack! Is Grover still around?
Yeah, but also not ready for this year.
I've packed up flywheel & clutch, and will swing by a machine shop tomorrow. If they can knock balancing them same day, then I can maybe put everything back together again. Long shot... fingers crossed.
I've packed up flywheel & clutch, and will swing by a machine shop tomorrow. If they can knock balancing them same day, then I can maybe put everything back together again. Long shot... fingers crossed.
If it still does it afterwards, try raising and lowering the trans in small amounts with a jack while its running, I had a nasty vibration years back that was from an HPM cross member throwing the angle out of wack on my 3550, shimming the mount height eventually fixed it.
Not sure I understand. Wouldn't jacking the trans just stress the connection to the bell or the trans mount?
Your not moving it ton, and a screw jack might work best, disconnect the trans mounts and do it with it in the air, it stresses the input shaft pre load more than anything as the motor mounts will absorb most of the movement and let the engine move a bit. with mine and the old HPM cross member it needed almost 1/2" of shimming between the mount and the tailshaft pad, mine was very rpm specific but happened in or at out of gear, but was worse on the highway at certain speeds,
When i had a vibration I couldn't find, it ended up being a dead injector. I was driving around on 7 cyl without even realizing it. Still ran damn strong like that.
My point is don't overlook something simple
My point is don't overlook something simple
I only skimmed the info but it started after clutch and or the work they did welding up the torque boxes and D/S loop, I'd expect its possible it changed the angles just enough. like the tko, the t56 doesnt share the same mounting pad height as a t5 so shimming is pretty important. I would look close at the cross member since stifflers can be assembled a few different ways by the bushings and spacers. I remember chasing a vibration like this this almost exactly with I put in the old HPM one, drove home from work after throwing it in, and it started to vibrate on the highway and it even had the vibration in neutral sitting still free reving by the time I got home. This was way back, stifflers wasn't even a company, HPM had the gold solid cross memeber sold specifically for tremecs, but It was a bind caused by the cross member. Can you measure drive line angles? With the old school hpm cross member not only did it throw off the angles but it also was binding on the tunnel itself, the raised section on the passenger side for the exhaust, clearance was paper thin between the floor board and amplifying the vibration, shimming the mount and extending the body side mount holes fixed it with zero vibration affer.
Yeah, I hear you. I remember that gold HPM crossmember from back when I had a TKO, which at the time was essentially just a 3550 with a 26-spline input shaft. This was before the TKO 500 and 600 came along.
I guess what I don't understand is why you were experiencing the vibration in neutral, especially if it was still present with the transmission in gear and the clutch fully depressed. Regardless, I'll eventually work through all of that.
I do have the equipment to measure driveline angles, and I've set the engine, driveshaft, and pinion angles with the Stifflers crossmember installed. In fact, it's the only crossmember I've ever used with the T56. What I haven't done is recheck those angles since installing the driveshaft safety loop. The loop added approximately 1/4" of plate above the transmission crossmember, so I removed roughly 1/4" of spacer to compensate. I didn't measure it precisely, though, so it's certainly worth revisiting.
First things first, though. I need to get this pressure plate checked out.
My regular machine shop said they couldn't balance it without the complete assembly. I called another shop, and I'm actually on my way home now to pick up a neutral-balanced flywheel because they can't do it with my 50 oz imbalance flywheel.
I really don't think the flywheel itself is the problem, unless the three locating dowels are somehow misaligning the pressure plate. After I get everything back, assuming I'm no longer racing the clock to make it to Foxtoberfest, I'll reinstall the pressure plate by itself and see if the vibration returns.
If the shop finds the pressure plate out of balance and can correct it in time for Foxtoberfest, I may just put everything back together and hope for the best. I'll make a quick attempt to check and adjust the pinion angle, but I won't have much time to get carried away with it. That can easily turn into a multi-hour ordeal.
I guess what I don't understand is why you were experiencing the vibration in neutral, especially if it was still present with the transmission in gear and the clutch fully depressed. Regardless, I'll eventually work through all of that.
I do have the equipment to measure driveline angles, and I've set the engine, driveshaft, and pinion angles with the Stifflers crossmember installed. In fact, it's the only crossmember I've ever used with the T56. What I haven't done is recheck those angles since installing the driveshaft safety loop. The loop added approximately 1/4" of plate above the transmission crossmember, so I removed roughly 1/4" of spacer to compensate. I didn't measure it precisely, though, so it's certainly worth revisiting.
First things first, though. I need to get this pressure plate checked out.
My regular machine shop said they couldn't balance it without the complete assembly. I called another shop, and I'm actually on my way home now to pick up a neutral-balanced flywheel because they can't do it with my 50 oz imbalance flywheel.
I really don't think the flywheel itself is the problem, unless the three locating dowels are somehow misaligning the pressure plate. After I get everything back, assuming I'm no longer racing the clock to make it to Foxtoberfest, I'll reinstall the pressure plate by itself and see if the vibration returns.
If the shop finds the pressure plate out of balance and can correct it in time for Foxtoberfest, I may just put everything back together and hope for the best. I'll make a quick attempt to check and adjust the pinion angle, but I won't have much time to get carried away with it. That can easily turn into a multi-hour ordeal.
Neutral vibration my best guess would be the cross member just barely making contact with the chassis, carrying the harmonics right to the floor, mine you could kind of feel it coming from the tunnel/ floor area. The t56 is pretty damn tight in a fox tunnel so I would definitely check clearances when you put it back together. Did they pull the cross member out or just remove the shim and replace it with the loop, could be they mixed up the spacing. You said its fine with the trans pulled so definitely pay extra attention to clearance when its going back in.
I read back a couple pages. Vibration in/out of gear and clutch in/out rules out trans and rearward. Have you looked at the damper in front? Always hear about them going bad. I assume yours isnt stock but still worth looking at I think.
Yeah I replaced that and I replaced the engine mounts before going back in to the trans clutch flywheel area
I figured as much. I had a bad vibration with the last engine as well that I could never figure out. Ill be curious to know how this plays out.
This tells me he's on the right track, either the clutch which I doubt unless the pressure plates bent or some rivets are tore up, most should be noticable or its a binding issue with the T56 that was made worse when the the torque boxes where welded up and the driveshaft loop was installed. Harmonics are crazy on cars, I've seem some really dumb
cause vibrations on stock oem stuff over the years doing dealer work. My only questions would be where are your feeling it the most, your feet on the floor, hands on the steering wheel, the shifter or ass in the seat.
I may have put this in an earlier post, not sure, but I felt it most actually with a friend rev in the car while I put my hands on eventually the outermost portion of the tail housing of the transmission and the drive shaft safety loop, which ends at about the same place. When I put my hand on the intake I felt nothing. And in the car it's an overall sensation the whole car is vibrating but it's clearly coming from the motor. 2100 RPM give or take and 4,000 to 4200 RPM seem the worst to me.
Well, gentlemen, I FINALLY figured it out. And I am absolutely blown away by what caused this damn vibration!
For those who haven't followed the saga, I had a relatively minor vibration around 4,000 RPM after replacing the clutch earlier this year. Then, after having the torque boxes welded and the Stifler's driveshaft safety loop installed, it became dramatically worse. By 2,000 RPM, the whole car was shaking enough that I was genuinely worried something inside the engine was coming apart.
What drove me absolutely nuts was that it followed engine RPM. Sitting still, moving, in gear, out of gear, clutch engaged or disengaged, it made no difference. Everything pointed toward the engine or rotating assembly.
So, here's the ridiculous road this sent me down:
- Replaced the harmonic balancer.
- Replaced the motor mounts.
- Replaced the spark plugs.
- Checked ignition timing and tried running without the SPOUT.
- Bypassed the MSD ignition.
- Ran three successful EEC cylinder balance tests.
- Checked for mechanical interference and anything transmitting vibration into the chassis.
- Investigated the clutch, flywheel, pressure plate, pilot bearing, and possible crankshaft imbalance.
- Finally pulled the transmission and clutch AGAIN to isolate the problem.
I became so convinced something was wrong internally that I even started on my next engine build. I've got a junkyard block sitting at a machine shop!
And here's where it gets ridiculous.
Sunday, I pulled everything back apart and ran the engine with nothing but the flywheel attached.
Smooth as glass! I don't think I've ever felt this engine run so smoothly.
AHA! Surely I've finally isolated it to the clutch or pressure plate!
Tuesday, I took the pressure plate and a neutral-balanced flywheel to a machine shop in Fayetteville. They found about 10 grams of imbalance in the pressure plate and corrected it, although they doubted that was enough to explain the vibration.
Reinstalled the clutch and transmission, fired it up, and everything was beautifully smooth. FINALLY!
NOPE!!!
Reinstalled the Stifler's driveshaft safety loop and driveshaft, took it for a test drive, and THE DAMN VIBRATION WAS BACK!
At this point, I'm about ready to lose my mind.
Pulled the safety loop back out, reinstalled the original aluminum spacer, and immediately took another drive.
VIBRATION GONE. COMPLETELY!
Black Jack drives absolutely beautifully now!
I'm including a picture of the original spacer beside the Stifler's mounting plate. I haven't measured them, but I'd bet they're both approximately 1/4" thick. The loop wasn't contacting the tunnel, either. There was plenty of clearance.
I still don't understand exactly how something hanging off the back of the transmission could produce such a severe vibration tied to engine RPM. My best guess is some kind of structural resonance. It absolutely blows my mind.
And I owe rednotch some serious credit! He kept pointing toward the transmission mounting arrangement and the possibility of resonance, even describing a similar experience with an HPM crossmember. I couldn't wrap my head around how that could explain an engine-speed vibration, particularly one that occurred while stationary. But he was absolutely on the right track! And when he asked where the vibration was strongest, I reported feeling it at the transmission tailhousing and safety loop rather than the engine. Pretty enormous clue in hindsight!
Frankly, I'm done experimenting with that thing. I'll install a conventional driveshaft safety loop and call it a day.
To add insult to injury, this whole adventure cost me my first day at Foxtoberfest. And it wasn't the only aggravation! One thing after another went wrong getting ready. The clutch cable broke, I lost HVAC vacuum, developed a new coolant leak (thankfully resolved), and of course had all this clutch and driveline nonsense to deal with.
I'm equal parts relieved, exasperated, and amused. I cannot believe how much time, money, and effort I've spent chasing something that ultimately came down to removing a driveshaft safety loop!
On the bright side, I've got new motor mounts, a new harmonic balancer, and a freshly balanced clutch assembly. The original engine apparently has nothing wrong with it, and the car drives better than ever.
Thanks to everyone who helped me work through this insaniity, especially @rednotch
Black Jack has made every Foxtoberfest since 2022, and this year WILL NOT be the exception!
Look out, Larry (@85GTStangGuy)! Here comes Black Jack!
For those who haven't followed the saga, I had a relatively minor vibration around 4,000 RPM after replacing the clutch earlier this year. Then, after having the torque boxes welded and the Stifler's driveshaft safety loop installed, it became dramatically worse. By 2,000 RPM, the whole car was shaking enough that I was genuinely worried something inside the engine was coming apart.
What drove me absolutely nuts was that it followed engine RPM. Sitting still, moving, in gear, out of gear, clutch engaged or disengaged, it made no difference. Everything pointed toward the engine or rotating assembly.
So, here's the ridiculous road this sent me down:
- Replaced the harmonic balancer.
- Replaced the motor mounts.
- Replaced the spark plugs.
- Checked ignition timing and tried running without the SPOUT.
- Bypassed the MSD ignition.
- Ran three successful EEC cylinder balance tests.
- Checked for mechanical interference and anything transmitting vibration into the chassis.
- Investigated the clutch, flywheel, pressure plate, pilot bearing, and possible crankshaft imbalance.
- Finally pulled the transmission and clutch AGAIN to isolate the problem.
I became so convinced something was wrong internally that I even started on my next engine build. I've got a junkyard block sitting at a machine shop!
And here's where it gets ridiculous.
Sunday, I pulled everything back apart and ran the engine with nothing but the flywheel attached.
Smooth as glass! I don't think I've ever felt this engine run so smoothly.
AHA! Surely I've finally isolated it to the clutch or pressure plate!
Tuesday, I took the pressure plate and a neutral-balanced flywheel to a machine shop in Fayetteville. They found about 10 grams of imbalance in the pressure plate and corrected it, although they doubted that was enough to explain the vibration.
Reinstalled the clutch and transmission, fired it up, and everything was beautifully smooth. FINALLY!
NOPE!!!
Reinstalled the Stifler's driveshaft safety loop and driveshaft, took it for a test drive, and THE DAMN VIBRATION WAS BACK!
At this point, I'm about ready to lose my mind.
Pulled the safety loop back out, reinstalled the original aluminum spacer, and immediately took another drive.
VIBRATION GONE. COMPLETELY!
Black Jack drives absolutely beautifully now!
I'm including a picture of the original spacer beside the Stifler's mounting plate. I haven't measured them, but I'd bet they're both approximately 1/4" thick. The loop wasn't contacting the tunnel, either. There was plenty of clearance.
I still don't understand exactly how something hanging off the back of the transmission could produce such a severe vibration tied to engine RPM. My best guess is some kind of structural resonance. It absolutely blows my mind.
And I owe rednotch some serious credit! He kept pointing toward the transmission mounting arrangement and the possibility of resonance, even describing a similar experience with an HPM crossmember. I couldn't wrap my head around how that could explain an engine-speed vibration, particularly one that occurred while stationary. But he was absolutely on the right track! And when he asked where the vibration was strongest, I reported feeling it at the transmission tailhousing and safety loop rather than the engine. Pretty enormous clue in hindsight!
Frankly, I'm done experimenting with that thing. I'll install a conventional driveshaft safety loop and call it a day.
To add insult to injury, this whole adventure cost me my first day at Foxtoberfest. And it wasn't the only aggravation! One thing after another went wrong getting ready. The clutch cable broke, I lost HVAC vacuum, developed a new coolant leak (thankfully resolved), and of course had all this clutch and driveline nonsense to deal with.
I'm equal parts relieved, exasperated, and amused. I cannot believe how much time, money, and effort I've spent chasing something that ultimately came down to removing a driveshaft safety loop!
On the bright side, I've got new motor mounts, a new harmonic balancer, and a freshly balanced clutch assembly. The original engine apparently has nothing wrong with it, and the car drives better than ever.
Thanks to everyone who helped me work through this insaniity, especially @rednotch
Black Jack has made every Foxtoberfest since 2022, and this year WILL NOT be the exception!
Look out, Larry (@85GTStangGuy)! Here comes Black Jack!
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Nice that you figured it out.
I run the same Stifflers driveshaft loop and don't have any issues at all.
I don't know if it has anything to do with me running solid engine mounts and a solid transmission mount or not.
I run the same Stifflers driveshaft loop and don't have any issues at all.
I don't know if it has anything to do with me running solid engine mounts and a solid transmission mount or not.
