Chasing a Vibration - Flex Plate?

[bigmal 225]

19 minutes ago, barnett468 said:

it can be a little worse/magnified when driving.

is the vibration cyclic or constant?

Thanks Barnett, it's cyclic. I am now thinking harmonic balancer. I will take it off today and order a replacement during the week. If not, at least I've eliminated that without too much work.

[barnett468 418]

That is not the balancer. It is a harmonic vibration most likely inside the engine. 

 

[RPM 1,190]

Hey Mal, I've chased a cyclical vibration since I got mine running over a year ago. I changed a bunch of parts including, wheels & tires, rear pumpkin, drive shaft, trans mount, all 4 rotors, and wheel bearings. My vibration only occurred when power was put thru the trans to the rear.  I read were a guy had removed his OE trans dampner and thought I'd locate one to replace the one "somebody" tossed out during teardown. I solved the vibration by reinstalling the trans vibration dampner.

The vibration returned a couple of weeks later. It is rpm sensitive, and occurs more frequently with 3.25 gears than 2.50 gears. 

 

Mustang Steve has replaced everything but the car body trying to chase his vibration. All of the vibration threads I've followed have a lowered stance, and/or a T5 swap involved. I believe the vibrations are due to drive line angles, until proven otherwise. I have not found the answer...yet.

 

Best of luck buddy.

[bigmal 225]

Thanks everyone for the suggestions.

Bob, I'm not sure what the transmission damper is. I have an FMX and don't recall seeing anything like this. And I do have 3.25 gears.

I pulled the harmonic balancer yesterday. I have had some suggest it could be this and other say no. I need to start eliminating things before I pull the engine and this is quite easy. It certainly looks about 48 years old so can't hurt.

I have a question re the seal. Mine leaks so needs replacing. The new seal pictured below is the one that came with a gasket kit. Is this the correct one and it looks like it may have a different style that has a flange on it.

Also, what are your thoughts on replacing the seal in situ. I'd rather not have to remover the water pump if I can avoid it.

[RPM 1,190]

It bolts to the lower rear vertical rib on the tail housing.

[bigmal 225]

6 minutes ago, RPM said:

It bolts to the lower rear vertical rib on the tail housing.

Thanks Bob, I've never seen one of these. Is this after market? Who sells them?

[1969_Mach1 333]

bigmal,  The 1969 351W used the old style timing cover and a front seal without a flange that installed from the back side (inside) of the timing cover.  The newer style timing cover uses a front seat with a flange and installs from the front side of the timing cover.  I don't know the year for the change.  I would think if you tried 1974 or newer it will be a seal with the flange like you need.  You can easily find the correct seal by looking at the pictures in online catalogs.

At some time the timing cover was replaced or it's a newer year motor.  Do you know what year the motor is?

I agree, even if it turns out to be something internal, I would start with the damper because it is easy and yours is about 48 years old.

I wonder if that weight shown in RPM's pictures a dealer installed item.  You know, per a tech bulletin, and only installed to stop particular vibration issues.  Only because I haven't seen anything like that on a Ford. 

[bigmal 225]

5 minutes ago, 1969_Mach1 said:

bigmal,  The 1969 351W used the old style timing cover and a front seal without a flange that installed from the back side (inside) of the timing cover.  The newer style timing cover uses a front seat with a flange and installs from the front side of the timing cover.  I don't know the year for the change.  I would think if you tried 1974 or newer it will be a seal with the flange like you need.  You can easily find the correct seal by looking at the pictures in online catalogs.

At some time the timing cover was replaced or it's a newer year motor.  Do you know what year the motor is?

I agree, even if it turns out to be something internal, I would start with the damper because it is easy and yours is about 48 years old. 

When I bought the car I was told the engine was from a 1970 mustang but I have my doubts. I have looked on line and seem to have found the correct seal and ordered one on EBay.

 

[mwye0627 44]

2 hours ago, RPM said:

It bolts to the lower rear vertical rib on the tail housing.

I have to wonder which transmission that was from.   When I worked for Watson Engineering, we did a lot of work with the Ford Engineering teams. We did a LOT of work on NVH (Noise, Vibration, and Harshness) issues.   Ford sent many different engineers to our facility, and in most cases their "Fix" was to hang different weight attachments to the component causing the vibration...   The really didn't care to Correct the Cause of the vibration, but rather to Dampen the vibration by adding additional weight to the vibrating component, which reduces the vibration to a lower frequency which would hopefully be less noticable...   I'll likely get in a lot of trouble for disclosing this information, but what the hell, I'm retired and I had no pension from Watson, so really, what could they do???

 

[1969_Mach1 333]

mwye0627, that's a good point.  Natural frequencies of object are inversely related to their mass.  So simply adding the weight wouldn't fix the cause of the vibration.  Like you said, it would simply move the vibration to a lower frequency and hopefully not be noticeable.  Do you have any more of their (cover up) repairs? 

[RPM 1,190]

I couldn't find a Ford number on this one, but I did remove one back in the mid 90's and threw it in the trash because I too had never seen one, and thought it was fugly. I had forgotten about it until I read about another guy installing one. I found mine on eBay, but  WCCC has listed them. 

[bigmal 225]

27 minutes ago, RPM said:

I couldn't find a Ford number on this one, but I did remove one back in the mid 90's and threw it in the trash because I too had never seen one, and thought it was fugly. I had forgotten about it until I read about another guy installing one. I found mine on eBay, but  WCCC has listed them. 

Thanks Bob. I just ordered the new balancer. Fingers crossed it will help. Hopefully will arrive by the weekend.

[bigmal 225]

well I changed the harmonic balancer. Very excited and the frigging thing wouldn't start. Turns out when I was showing a mate how my GPS tracker works I disabled the engine. Once I sorted that out and recharged the battery I got it started. Well at least I can rule out the harmonic balancer. It made no difference. But it is shiny and new so not a total waste of time.

Barnett, you said not he balancer but inside the engine. Could you give me a little more. Are you suggesting getting the engine balanced? Of something else? Thanks.

[DocWok 30]

Hey Mal,

I had a cyclic vibration on an earlier mustang I owned.

Like you I tried many things, but no luck.

One day just for the hell of it I disconnected the cooling fan and took it for a test drive.

It ran smooth as silk, so I replaced the fan and for me, problem solved.

[det0326 179]

As Docwoc mentioned to check the fan or really anything externally that moves before removing any major components to see if it solves your problem. I am very suspicious of your flex plate that was marked with a felt pen. I wounder if the flex plate may be 50 ounce imbalance.  

[bigmal 225]

Thanks DocWok and det0326 I will try the fan this weekend. I need to eliminate the easy stuff before getting into the engine. Could be a good excuse to go to electric fans.

 

[barnett468 418]

19 hours ago, bigmal said:

well I changed the harmonic balancer. Well at least I can rule out the harmonic balancer. It made no difference.

Barnett, you said not he balancer but inside the engine. Could you give me a little more. Are you suggesting getting the engine balanced? Of something else? Thanks.

In my experience with well over 1000 cars, cyclic vibrations are almost always caused by an internal engine problem which balancing the engine almost always cures.

I mentioned that it wasn't the balancer previously because a bad balancer can not really cause a cyclic vibration or at least a bad stock type balancer can not.

At this point I would do the tests suggested by others first since they are free and easy to do. Also check the motor mounts. One last test could be removing the converter then bolting the trans back up and running it. If it still does it then, it is definitely in the engine.

 

 

 

 

[bigmal 225]

3 minutes ago, barnett468 said:

In my experience with well over 1000 cars, cyclic vibrations are almost always caused by an internal engine problem which balancing the engine almost always cures.

I mentioned that it wasn't the balancer previously because a bad balancer can not really cause a cyclic vibration or at least a bad stock type balancer can not.

At this point I would do the tests suggested by others first since they are free and easy to do. Also check the motor mounts. One last test could be removing the converter then bolting the trans back up and running it. If it still does it then, it is definitely in the engine.

 

 

 

 

Thanks for that. I will have the engine out later this year to change the heads and cam so if its not one of the things suggested here I will continue stripping the engine and do a full balance.

[barnett468 418]

6 minutes ago, bigmal said:

Thanks for that. I will have the engine out later this year to change the heads and cam so if its not one of the things suggested here I will continue stripping the engine and do a full balance.

Wish I had better news but hopefully you will get lucky and it will be external. It happens once in a while.

 

 

 

[bigmal 225]

1 minute ago, barnett468 said:

Wish I had better news but hopefully you will get lucky and it will be external. It happens once in a while.

 

Thanks mate

[barnett468 418]

6 minutes ago, bigmal said:

Thanks mate

No prob, and if you do need to balance it, start a thread on the ozzie mustang site. shaunp and glenn and a few others might know a reliable place near you. Wherever you go, just don't get it done were fitzy got his done, lol.

[bigmal 225]

Thought I would add a short video of the vibration running at around 1700 RPM

[det0326 179]

Mal

In this video I assume you have the rear axle on jack stands and the whole drive train is turning. Is this correct?  Also is the vibration as noticeable with just the engine running? 

That's a pretty big vibration the way the steering wheel is vibrating or is that just a nervous camera . 

[Shep69 149]

Shit that’s a bad vibration  Mal the way your steering wheel is moving. 

That’s got to bloody frustrating. I gather you have eliminated the wheels and tail shaft by removing them and running it up on stands. 

[RPM 1,190]

On 6/24/2018 at 3:56 PM, bigmal said:

When I bought the car I was told the engine was from a 1970 mustang but I have my doubts. I have looked on line and seem to have found the correct seal and ordered one on EBay.

Just fyi, the 69 has a 3 bolt crank pulley, while the 70 and up is 4 bolt.