Need Some Help Solving Vibration Problem

[93gtmustang]

My engine had the wrong balancer (28oz.) on it. It had a vibration from 1000-1500 rpms. (shook the steering wheel) I just recently had the right balancer put on (50 oz.) and it vibrates between 4000 and 5000 rpms. (not as hard of a vibration) This happens when driving down the road, stationary, out of gear, clutch disengaged or engaged.
It's totally smooth otherwise. I brought it to an engine builder I know, and he said that the car had been in an accident before I bought it . ( Motor mounts are new) I have no history of what has been done to this engine. It runs strong, even with 124000 miles on it. I drag raced it hard all summer with the 28 oz balancer on ( that's what I use the car for, not a daily driver)
My mechanic said it could be a number of things. Bent crank, broken crank, wrong flywheel, flywheel out of balance, clutch out of balance etc.... But where do you start?
By the time he goes through everything to find the problem and repair it, I could have had him throw in a 345 hp Ford Racing Crate Motor for a couple thousand dollars more. I was going to have him start with a new clutch set-up and zero balance the flywheel to see if that works. If that's not the problem, that would be the start of spending loads of money on an engine that has 124000 miles on it and no knowledge of what kind of condition the insides are in. I'm torn between a new engine or fixing this one. Other than the vibration, this engine runs great!!! 14.2 ET 1/4 mile
Some advise on which way to turn would be greatly appreciated!!
Thanks!

1993 GT Mustang / Stock 302 EFI / Edelbrock 5.0 Upper and Lower Intake / 75mm Throttle Body / C&L Cold Air w/76mm Mass Air / K&N Filter / Electric Fan / BBK Underdrive Pulley's / A.C. Removed / BBK Headers / Flowmaster / H-Pipe / T-5 / Alum. Driveshaft / 3.73 Gears / Eaton H.D. Posi / Moser 31 Spline Axles/ Subframe Connectors / Line Lock / Driveshaft Loop / B&M Short Throw Shifter / 16" Chrome Cobra Wheels / Nitto Drag Radials Rear / BFG G-Force Sport Front / Racing Upper and Lower Control Arms / Lakewood Adjustable Drag Shocks/ Holley 190 lph Fuel Pump / Holley Adjustable Fuel Pressure Regulator / MSD EFI Blaster Coil/ Stock Heads/ 19# Injectors

 

[TheUser]

I'm not sure where to suggest you start. In addition to his list, I would also suspect that the main bearings might be worn wrong from the wrong-sized balancer.

I don't think there really is a way to tell without trial and error.

I'm not sure what I would do in your situation. Sounds like it's gonna be a money pit either way you go.

 

[jk351w]

oh man...well, first of all - your rotating assembly definitely took a beating. it could be the main bearings and if thats the case you shouldn't even drive the car. other causes (if you didn't have the wrong damper) could have been a drive shaft, tranny, etc. def. have the internals looked at. good luck to ya

 

[93gtmustang]

And here's the worst part. When I bought the car, last year at this time. I sent it down to a "race shop". I wanted 3.73's put in, which were not set properly I just found out. They have a whine to them. H.D. Eaton posi, 31 spline moser axles , alum drive shaft. subframes. I had them start at the rear and had them just check the rest of the car (trans. and engine). The owner said that the car had been in an accindent (I didn't know this when I bought it) and he repositioned the engine(got it as straight as he could) and put new motor mounts on. Also the balancer was spun , so he put a new balancer on. When I picked the car up he told me about the balancer and said that there was a vibration between 1000 and 1500 rpms but don't worry about it. So I did worry about it and called the shop back in a couple of days and voiced my concern over the vibration. Green as I was then , I knew something was wrong. One of the employees put me on hold, talked to the owner and said that the owner said it was ok not to worry. When I asked why it has a vibration now at 1000-1500 rpms and it didn't have a vibration when it was brought to them , they said maybe the spun balancer had adjusted itself to the engine and with the new balancer there is a vibration.The employee said if the owner said it was ok it was fine by him, so not to worry he asured me. I raced it all this summer with the vibration only between 1000 and 1500 rpms. It ran strong, I ran it hard, 14.2 et in the 1/4 mile best 14.3 consistantly. When I wanted to swap the transmission to a c-4, the transmission company wanted to know the balancer weight. I assumed 50oz but I called the race shop to double check. They punched in the part number off my invoice and it came up 28 oz. They didn't even know that was the wrong size balancer. They blamed the machine shop for giving them the wrong balancer which is lame. They put the right one on for me no charge. When I asked if running the wrong balancer for 9 months could have caused the vibration I have now and done some engine damage, they said no it didn't and how do we know there wasn't a vibration before you brought it down to me. And to be honest, I never had it up to 4000 or 5000 rpms when I first bought it so I really don't know if it was there or not. So I really don't know where to start. It's definately never going back to that race shop!!!

 

[93gtmustang]

Does anyone else have any suggests?

 

[TheUser]

Sounds like you're just screwed - sorry to say.

My advice would be to start doing your own work if possible. If you're not mechanically inclined, it's ok, but you might start asking to check part numbers (or supply the parts) to a reputable shop. In that case, I guess you could ask around and find a good shop - preferably one familiar with Mustangs.

If your main bearings are worn, the geometry of the internals will most likely be mis-aligned and the only way to fix that would be to rebuild the engine. In that case, you'd probably want to replace the main bearings, rod bearings, rings, oil pump, etc.

Otherwise, you could just drive it how it is until it blows. You could then bore the block, which would require new pistons anyway. The only thing is I don't know how much damage would be done to the crank w/ the main bearings worn - and I'm not sure if a machine shop grinding it .010 would take care of it.

 

[93gtmustang]

Yeah your right . I got screwed!!. I do have a mechanic 1 mile down the road. He's and engine builder, rear ends , everything, drag raced mustangs for 30 years. I should have went to him in the first place. I am going to go with the 345 hp crate and a tremec and have him do all the work. It's just not worth it with all the problems with this engine. It's wierd, It does run great and strong. I am ordering all the parts. I've been talking to Ford Racing about everything so I get all the right parts. Thanks for all the help User, I appreciate it. You've helped me make up my mind.

 

[TheUser]

Well, although I did suggest that you might need a rebuild, I didn't intend to suggest that you spend thousands of dollars on a crate engine - that's your decision, though. You might consider asking your mechanic what he would charge for a rebuild and compare that to the purchase of the new crate enigne.

You don't have to spend all that money to get the car to run again, but that certainly is one option.

Good luck! Let us know how it turns out:SNSign:

Also, I want to re-enforce that I'm not a Professional engine builder, nor a professional mechanic, so my opinions of what is wrong and needs to be replaced is only a guess. I did manage to rebuild my enigne, but that certainly does not make me an expert by any stretch of the imagination.

 

[93gtmustang]

I realize that. I have talked with him, and it could cost as much as throwing a new crate in, depending on how far he had to go. I'm not holding you liable for my decision making. But your opinions do back up my gut instinct of going all new with almost no worries. I want a car that I can rely on at the track, still drive it on the street once in a while, and not have to work on it all the time or be worried about what is going to go next.
The reason I'm having such a hard time , is that it could be something as easy as a wrong flywheel or as bad as a bent or broken crank. Thanks for all the help though.