Experts Needed - Engine Vibration - Problem Undetectable...NOW FIXED!!!

[Needa68]

All,

Any help someone can provide here would be appreciated. As you will read, we have tried our best to toubleshoot this issue as best we can, but our problem still remains. Here is the scenario and background.

Vibration Problem


Our Dodge recently developed a vibration. It's most noticeable at 45 MPH. We have ruled out the rear end, drive shaft and front running gear. This was done by removing the drive shaft then starting the engine, putting the transmission into gear and then accelerating to 45 MPH per the speedometer while setting still.


The engine is a 1970 model 440 cid, bored 60 over. It has a forged steel crank, a slightly over stock cam and flat top pistons with stock heads that produce a compression ratio of 10.25:1. The engine is matched to an A-727B Torqueflite automatic transmission.


The vibration began shortly after installing a 2600 - 2800 stall torque converter. Given this was the most recent change made we opted to reinstall the stock torque converter. Doing so did NOT fix the vibration problem but replacing the 2600 - 2800 stall torque converter did screw up what had previously been a great shifting pattern.


In our quest to find the vibration we then turned our attention to the engine. First we conducted a compression test. Each cylinder was within 1 PSI of the others at 150 PSI. No smoking gun there!


Next we raised the #1 piston to top dead center then checked the alignment of the harmonic balancer (damper). It was spot on! No smoking gun there either.


After doing some reading we became concerned the rubber which bonds the inner hub to the outer ring of the damper might be slipping when the engine is running. Disregarding our previous test which indicated the damper was good we bought and installed a new SFI bonded steel crankshaft damper. It's very pretty, but didn't fix the vibration problem.


We've inspected the engine and transmission mounts. They appear to be in very good condition. Short of replacing them we are trying to come up with a way to determine for certain if one has broken down and in doing so is transmitting vibrations to the frame.

We are out of ideas that don't cost big bucks. We are considered swapping out the 727 transmission. We have another but it needs to be rebuilt. We will eventually need it for a 68 Charger we are restoring but that need is several months away.

If anyone out there has experienced somnething similar or has solid recommendations, we would very much appreciate hearing what was done to correct the problem. Thanks in advance!

Rob Mitchell

Mitchell & Mitchell 1968 Dodge Coronet R/T Restoration:

www.geocities.com/robertmitchell32000


Mitchell & Mitchell 1968 Dodge Charger Restoration BLOG:

http://geocities.com/robertmitchell32000/CHARGER/TheMitchells68Charger.html

[firefighter3931]

Couple of questions ;

(1) was the engine internally balanced ?
(2) Is the correct torque converter installed ? Does it have weights on it ?
(3) stock or aftermarket flex plate ?
(4) has the flexplate been checked for cracks ?


Ron

[beedees]

In 1970 Chrysler switched HP 440 internals, specificaly the rods, going to the "6 pack" engine rods. I believe these engines required a different balancer from LY rod engines. Are you sure you have the right balancer from ATI  (or wherever)?

[RD]

did you check the converter when installed to see if there was any up/down/side to side movement while seated into the trans pump?

[Challenger340]

Can you hook up a tach, and try the engine in neutral @ whatever rpm corresponds to the same 45 mph ?

Does it vibrate at that rpm in neutral ?

[i c e b l u e]

i agree with the the above posts. I would also look into the front fan and water pump. Of course when you installed the new damper im sure you would have noticed if the fan bolts were loose. However, we had one car come into our shop that had a bent water pump shaft(at least the tip was bent) that didn't leak any water and was nowhere near noticeable until about 3000 and progressively got worse. Probabbly 1 in a mill but it want cost you anything to check

have you checked spark in all cylinders? Have you used a gas analyzer or wide band? A simple aproach would be a dead cylinder check by pulling the wire off of one plug at a time and noting the rpm drop. no rpm drop = dead cylinder.

personally it sounds like a balance issue, but these are a few easy things to check

[Todd Wilson]

I'd check the pulleys and stuff attached. Alt,water pump,PS pump, AC. I had an AC pulley a few years back that drove me crazy. Made a noise/vibration at a certain speed only.  I had went thru thing and checked things and was about a day away from going to the transmission shop as you could hear it down in the floor.    Take off your belts and fire it up for a minute and see if its there or not.

Also make sure something isnt touching like exhaust or something ever so slightly touching anywhere that isnt normal as you could be getting a harmonic noise/vibration that way.



Todd

[Needa68]

Excellent recommendations from all. Thanks everyone! I'll respond to each of you in this one reply.

Todd Wilson: I should have mentioned we removed all belts from the water pump and the like. After doing so the vibration was still there.

I've not perform the exhaust inspection you recommend. I'll put the car on a rack and do that today.

iceblue: Good tip about the bent water pump shaft. We had this type problem once with a bent radiator fan shaft. Another time it was a froze up fan clutch. Both made the entire car shake. The water pump has been on the engine about a year but we'll give it a good inspection. The fan and fan clutch were inspected when installing the new harmonic damper.  Who knows! If it's not the shaft maybe a bearing or bushing has failed.

We've done a spark check of each cylinder. There was a noticeable drop in RPM when each plug wire was removed.

We agree that it sounds like a balance issue thus we made sure we installed the correct damper and torque converter. Both are for an internally balnced steel crank engine.

Challenger340: We thought about doing this once but forgot to do it once we convinced ourselves to change the harmonic damper. We'll do as you suggest!

RD: Yes! The converter (both) fit snuggly and had no side to side or up and down play.

beedees: Unfortunately we didn't overhaul the engine so we don't know exactly what the rotating system consists of. The engine was rebuilt shortly before we purchased the car. We do know it has Keith Black flat top pistons and a steel crank that was polished during the rebuild. I'm not sure if the rods were reused or not. I seriously doubt the rotating assembly was balanced but will try to contact previous owner and confirm. According to the engine stamp up near the distributor it was not an HP model from the factory. I'll need to research to determine if 6 pack rods were used in non-HP engines. We made sure we installed the correct damper and torque converter. Both are for an internally balanced steel crank engine.

firefighter3931:

1) Was the engine internally balanced?  Answer: We don't believe it was! Checking with previous owner to confirm.
(2) Is the correct torque converter installed ? Does it have weights on it ? Answer: We believe we have the correct converter. It has no external weights.
(3) Stock or aftermarket flex plate? Answer: Aftermarket! Changed twice! Also checked to ensure plates weren't altered to serve as a counter weight (extra hole or change in physical shape).
(4) Has the flexplate been checked for cracks?  Answer: Yes and replaced twice out of desperation.

Again, thanks for the support! We are off to the shop to see what we can find. If anyone has another suggestions, please post them. As you can probably guess we really don't want to tear the engine apart except as a last resort.

Oh! I should also report that the new damper had some effect on the vibration or that the problem maybe getting worse. The vibration is no more intense but is now very strong at 35 MPH up to about 55 MPH after which it sort of levels out but can still be felt.

 

[firefighter3931]

beedees: Unfortunately we didn't overhaul the engine so we don't know exactly what the rotating system consists of. The engine was rebuilt shortly before we purchased the car. We do know it has Keith Black flat top pistons and a steel crank that was polished during the rebuild. I'm not sure if the rods were reused or not. I seriously doubt the rotating assembly was balanced but will try to contact previous owner and confirm. According to the engine stamp up near the distributor it was not an HP model from the factory. I'll need to research to determine if 6 pack rods were used in non-HP engines. We made sure we installed the correct damper and torque converter. Both are for an internally balanced steel crank engine.

firefighter3931:

1) Was the engine internally balanced?  Answer: We don't believe it was! Checking with previous owner to confirm.
(2) Is the correct torque converter installed ? Does it have weights on it ? Answer: We believe we have the correct converter. It has no external weights.
(3) Stock or aftermarket flex plate? Answer: Aftermarket! Changed twice! Also checked to ensure plates weren't altered to serve as a counter weight (extra hole or change in physical shape).
(4) Has the flexplate been checked for cracks?  Answer: Yes and replaced twice out of desperation.

Ok, now we're getting somewhere. The KB pistons are much lighter than a stock piston. If the engine assembler did not internally balance the motor that is a problem. The 6-pack rods are also quite heavy and difficult to balance internally....if that 70 motor has those, which it should assuming the rotating assembly is stock....will cause further imbalance issues.

I was hoping it would be simple....something like a mismatched converter/fleaxplate but no such luck. 

I'm afraid that the engine will be coming out and torn down to see what you've got inside. The Factory LY rods will have a 535 stamped on them....the 6-pack rods have a different stamping but i can't recall the number off hand. If it has a set of LY rods you will be able to internally balance it. You might be able to internally balance with the 6-pack rods but that usually costs big bucks (mallory metal) and you would be further ahead purchasing a new set of aftermarket H-beams (Scat/Eagle/440 source etc...) than trying to fix that mess.


Let us know what you find.


Ron

[max]

the so called six pack rods end in a casting # 908.

these rods were used in all HP 440's from 1970 through 1974 and i have even seen them in truck engines all the way up to 1978.

they use a special damper for the front of the engine as in the photo which is marked as 6 pack.

yes the KB's will be lighter then stock pistons but since the engine is .060 then that might bring the weight back to what a stock bore 440 piston weighs.

the 1970-1974 hp engines are strange and i have read both ways that one, they didn't need a weighted flex plate if they didn't have 6 pack pistons which are taller and have 4 valve reliefs or two they needed a weighted flex plate because they did have 6 pack pistons.

B&M sells a flex plate that is weighted and it specifies it is for the 1970-1974 440 hp engines and it doesn't state that it is for use in a non six pack piston.

[Needa68]

Ron and Max: Thanks for the info you guys provided. Interesting stuff! We hate the idea of having to tear the engine down but what can you do?Before we do tear it down we will contact the previous owner and find out exactly what he had done to the engine or maybe I should say not done. We had no idea the 70-74 440's had the heavy 6 pack rods in them. It wouldn't surprise us to learn the people who rebuilt the engine didn't know this either.

For the time being our R/T is parked. We made a valiant effort to get it ready to attend the Lone Star Shootout MOPAR Show and Race tomorrow at Houston Raceway Park but came up short. If either of you attend that show and see an old grey haired guy with a very sad looking face talking about a sick 68 Dodge you'll know you just saw the elder half of needa68. Thanks again for your responses.

[firefighter3931]

Bob ; i checked out your website....very cool pics ! 

Is that the same Coronet that you were married in ?

Sorry about missing the show....but better safe than sorry.    I'm sure you guys will still have a blast anyway. 

Update us with info as it becomes available....don't worry it can be fixed. 



Ron

[Challenger340]

Geez, great website, and beautiful Car !
You should be proud RHM.

[Needa68]

We attended the Lone Star Shootout MOPAR Show and Race at Houston Raceway Park yesterday  but without our MOPAR  . As reported earlier it is parked awaiting further diagnosis.

Just in the off change it will help we picked up a new transmission mount  . We'll install it in the near future. We also spent time trying to find a tailstock and driveshaft for the second A-727B we have. No luck there but we did score several other parts we need for our Charger to include a rear deck panel with built in grills for the speakers  .

There were several excellent Chargers on display but one in particular caught our attention. Between 1994 and 1998 the 67 Charger shown below was converted to a pick up truck. I know that sounds like something a redneck Texans  would do but it was actually done by two MOPAR fans from Kentucky. We were impressed with their craftsmanship .

The Charger is now owned by a Texan and as such the engine has been upgraded to a 1970 440 cid. This vehicle is clean and well thought out. You can tell some serious planning and execution went into its transformation. We didn't stay around to hear the result but if this vehicle didn't win the modified class it should have.

[Just 6T9 CHGR]

That car/truck was at Carlisle this year...very interesting!

[max]

i'm usally not a fan of mods like that but that charger/truck looks good, coarse i could have done with out the side marker lights to make it look cleaner.

[firefighter3931]

I like it...very cool truck ! 


Ron

[Needa68]

Ron (firefighter3931):

In a previous reply you asked "Is that the same Coronet that you were married in?"

Yes, the B5 Blue one with white strips I bought new in Sioux City, IA. It was about the only thing I owned in November 69 when my wife and I got married in Ajo, AZ. I went to Viet Nam shortly after we got married. She drove the R/T while I was gone during which time she attended Arizona State. We sold the car in Georgia after I returned from Viet Nam and just before being transfered to Germany. Here is the sad part! We bought a new Pinto to take to Germany because we were told gas was $2.00 a gallon.

Bob

[Needa68]

Today, after taking a couple days off we made another attempt at finding the cause of the vibration. We started from the beginning only this time we put the car up on floor jacks, got under it on creepers and searched for possible causes while lying on our backs. The first thing we found was that a bracket that holds the Lokar kick down linkage to the transmission was pressed up against the transmission tunnel wall. We corrected this by repositioning it.

Next we noticed that the transmission tail stock was not centered in the tunnel. It was off center to the passenger side. This caused us to take a closer look at the transmission mount. It appeared to be compressed but we weren't sure this was the case. Using a small hydraulic jack and a piece of wood we raised the end of the tail stock. When we did the transmission moved back toward center maybe 3/8 of an inch. Feeling we were onto something we then loosened the motor mounts then lowered and raised the tail stock again. Again the tail stock moved back toward center only this time it moved maybe 5/8 inch. We then tightened the motor mounts.

With the jack still supporting the tailstock we started the engine, put it in gear and ran it up to 45 MPH per the speedometer. This is the speed the vibration was at its worse previously. This time the vibration was gone. Problem solved!!!

We purchased a new transmission mount over the weekend. Later this week we will again pull the transmission, reinstall the 2600-2800 stall torque converter and replace the transmission mount.

Thank you to all who suggested possible solutions.

[firefighter3931]

Ron (firefighter3931):

In a previous reply you asked "Is that the same Coronet that you were married in?"

Yes, the B5 Blue one with white strips I bought new in Sioux City, IA. It was about the only thing I owned in November 69 when my wife and I got married in Ajo, AZ. I went to Viet Nam shortly after we got married. She drove the R/T while I was gone during which time she attended Arizona State. We sold the car in Georgia after I returned from Viet Nam and just before being transfered to Germany. Here is the sad part! We bought a new Pinto to take to Germany because we were told gas was $2.00 a gallon.

Bob

Bob, that's a cool story...well other than the Pinto deal. I'm sure you've regretted that move many times over. 

Good to see you're back where it all started. 


Ron

[firefighter3931]

Today, after taking a couple days off we made another attempt at finding the cause of the vibration. We started from the beginning only this time we put the car up on floor jacks, got under it on creepers and searched for possible causes while lying on our backs. The first thing we found was that a bracket that holds the Lokar kick down linkage to the transmission was pressed up against the transmission tunnel wall. We corrected this by repositioning it.

Next we noticed that the transmission tail stock was not centered in the tunnel. It was off center to the passenger side. This caused us to take a closer look at the transmission mount. It appeared to be compressed but we weren't sure this was the case. Using a small hydraulic jack and a piece of wood we raised the end of the tail stock. When we did the transmission moved back toward center maybe 3/8 of an inch. Feeling we were onto something we then loosened the motor mounts then lowered and raised the tail stock again. Again the tail stock moved back toward center only this time it moved maybe 5/8 inch. We then tightened the motor mounts.

With the jack still supporting the tailstock we started the engine, put it in gear and ran it up to 45 MPH per the speedometer. This is the speed the vibration was at its worse previously. This time the vibration was gone. Problem solved!!!

We purchased a new transmission mount over the weekend. Later this week we will again pull the transmission, reinstall the 2600-2800 stall torque converter and replace the transmission mount.

Thank you to all who suggested possible solutions.

Good luck Bob....i sure hope that the trans mount turns out to be your problem. 

Let us know how it turns out. 



Ron

[Needa68]

We re-installed the 2600-2800 stall torque converter and the new transmission mount today. The vibration problem is fixed. I'm not even going to try to figure out how much a $15 part cost us to find and replace.

Again, thanks to everyone for your support.

RHM,Jr.

[Just 6T9 CHGR]

Crap...I changed my mount twice & I still have a vibration

Good to hear you got yours fixed though

Im going to edit your title to show that you found a solution.....

[firefighter3931]

We re-installed the 2600-2800 stall torque converter and the new transmission mount today. The vibration problem is fixed. I'm not even going to try to figure out how much a $15 part cost us to find and replace.

Again, thanks to everyone for your support.

RHM,Jr.

Super ! 


Ron

[jlb1pi]

Ron (firefighter3931):

In a previous reply you asked "Is that the same Coronet that you were married in?"

Yes, the B5 Blue one with white strips I bought new in Sioux City, IA. It was about the only thing I owned in November 69 when my wife and I got married in Ajo, AZ. I went to Viet Nam shortly after we got married. She drove the R/T while I was gone during which time she attended Arizona State. We sold the car in Georgia after I returned from Viet Nam and just before being transfered to Germany. Here is the sad part! We bought a new Pinto to take to Germany because we were told gas was $2.00 a gallon.

Bob

Man, Bob....what we did in the 70's for fuel economy!!  I traded in my "owned since new" 72 Charger SE Brougham in 76 for a new Chevy Monza. My wife convinced me we needed the fuel economy for her 60 mile daily round trip to the  CA State University.  Get this: I let them give me 1500 trade-in for it!! It took me 31 years to find another one just like it to restore, and I've always felt bad about the whole thing....until I read your Pinto story...my story is only second best now!!  Glad to hear your vibration problems are over!!

Jer