High frequency flathead 6 engine vibration

[PT81PlymouthPickup]

Don,

Cool! Looks like a robust repair.What is holding the bushing into the flywheel? Just a precise fit?

[Jerry Roberts]

On 9/19/2016 at 5:48 AM, PT81PlymouthPickup said:

I did not use a kit. Bell housing was removed and machined to perfectly adapt the T5

Did you ad a thin spacer around the front bearing retainer ?  In Tom Langdons kit there is a thin sheet metal spacer that you would heat shrink in place to fill the gap and prevent vibration for the truck installation .  

[Don Coatney]

On 9/19/2016 at 7:01 PM, PT81PlymouthPickup said:

Oh yeah! Anybody knowing of a really good rebuildable mopar flathead L6 engine laying around for sale in my area I would like to know about it.  Did I mention, I'm pretty cheap too. Lols!

Check the links  section of this web page for a guy named George Asche. He may be able to help you out with an engine.

1 hour ago, PT81PlymouthPickup said:

Don,

Cool! Looks like a robust repair.What is holding the bushing into the flywheel? Just a precise fit?

The inner taper of the flywheel holds the bearing puck in place.

[PT81PlymouthPickup]

Jerry,  I did not like that approach. Probably would work OK, but seemed too flimsy to me, so if I remember correctly, I machined a step in the front bearing retainer and made a steel adapter ring to fit that and the bell housing hole diameter. Made it with a close fit. When you tighten the front bearing retainer bolts it's not going anywhere! It's more robust then just a thin spacer.  If you have acess to a lathe and a little experience, it's a fairly easy job. Toughest part is locating a piece of steel tubing to make the adapter from. You could machine it from a solid, but would be more difficult.

[PT81PlymouthPickup]

Don,

I like your approach on the pilot bearing. That may have worked for mine as well? But, I'm not sure. I think our flywheels might be different? Problem I had was finding a clutch disc with the same outside diameter and the right spline to fit the shaft.

[Don Coatney]

An off the shelf disc for an S-10 worked for me.

 

[PT81PlymouthPickup]

Yeah! I'm pretty sure my clutch disc is a larger diameter than yours. I guess that makes sense being mine is a truck.

[Don Coatney]

My original P-15 disc was 9 1/4" and I believe my replacement was close to the same.

[NiftyFifty]

I used an s-10 disc in my truck t5 swap with the stock dodge pressure plate...works just fine

[Merle Coggins]

9 hours ago, PT81PlymouthPickup said:

Yeah! I'm pretty sure my clutch disc is a larger diameter than yours. I guess that makes sense being mine is a truck.

You must have the 10" clutch. Is your flywheel drilled for a 9" clutch too? I think some were drilled for both. If so you could maybe get a 9" clutch assembly and use the S-10 clutch disc like the other guys have used.

[PT81PlymouthPickup]

I'll crawl up in the attic tonight. I've got a spare original disc and pressure plate up there to measure. Sure would make things easier if I could use an S10 disc. I thought at the time I did the swap, I should have a disc that matched the pressure plate diameter. I have no idea now if there were additional holes in the flywheel for a smaller pressure plate.  I kinda doubt it. My truck was built in 1939. The first year of this design. Did you guys use the S10 pressure plate in your installs? I can't imagine they would bolt in without drilling the flywheel?

[NiftyFifty]

Didn't use the s10 pressure plate, just the clutch disc, but it is definitely smaller then the pressure plate, but it still fits fine on the surface, just doesn't cover it completely like the original.  I've got 1000's of miles on mine, and it's working just fine..I did have to adjust the clutch this year, but I didn't set enough free play in the pedal from the start, so I think it was finally starting to hold it up a bit

[Don Coatney]

I used a Plymouth pressure plate that I had rebuilt and a off the shelf S-10 disc.

 

[PT81PlymouthPickup]

Well, I crawled up in the attic and yep, the original disc was definitely a 10 inch diameter. Sounds like a 9 inch disc S10 disc would have worked OK with a 10 inch pressure plate. I guess I was too fussy? I had a custom 10 inch disc made with a splline that matched the T5. Well, if I live long enough to replace it, I'll go with a 9" off the shelf disc. All this brings me back to my original dilemma. The harmonic balancer! I just ordered a hub and a balancer I found on ebay. (for almost $200.) Geez! I must be nuts, but hell or high water, I'm going to adapt it to my wide belt pulley. If it does not improve the vibration, the transmission comes out and I'll see if I can get the flywheel  and pressure plate checked out for balance.

 

[Young Ed]

Not sure that's the right combo. I and a couple others are running 9.25 pressure plates with the 9 s10 disk. Not sure I'd want a full inch hanging out there like that. 

[PT81PlymouthPickup]

Yeah Ed! That's why I had the custom disc made. I'm not sure if it would be OK either? It might work OK, It's actually only 1/2 inch hanging out per side,  but I'll most likely be dead by the time I wear this clutch out. Lols!

[Los_Control]

Where do you feel it?

Is it in the seat of your pants, or the steering wheel?

I had a 51 ford with bad king pins, get it to certain speed/rpm on the highway and it would shake like it was going to fall apart.

Only way to stop it was to pull over to a stop , take off again.

But where you feel the vibration, will help eliminate a lot of possibilities..

[59bisquik]

Just throwing this out there... but why a double cardan drive shaft? Since it does it under acceleration,  is it possible the driveshaft and or angles could be set up incorrectly? Pinion rise under acceleration can cause crazy vibration. 

I have had this issue on off-road vehicles in the past where lots of suspension travel could cause funky driveline angles. Could be a simple inspection with an angle finder.

 

 

[PT81PlymouthPickup]

I don't believe so? But, I could be wrong.  I had this vibration when I first restored the truck years ago. I suspected the driveshaft back then. The old cross and ball joints that came with my truck are technically a constant velocity joint, but they were worn and need of replacement. The holes where the bearing shafts pressed into the drive shaft ends were elongated.  I carefully engineered a new double cardan driveshaft and installed it including setting the correct pinion and drive shaft angles while also installing a new differential at the same time. The vibration I now have is exactly the same as it was before the transplant. So, I'm pretty certain the problem lies elsewhere? I believe I've narrowed it down to engine, flywheel, or pressure plate? But, having worked on mechanical stuff for a long time, I'm really not certain. Weird stuff can happen! And, Yes, it's is usually simple once you figure it out. I'm struggling figuring this one out.

[NiftyFifty]

The big answer is if you can make it do it at all at a stand still, you've eliminated the driveshaft, and once driving under load, you now amplify the engine issue because it will transfer through the rest of the driveline.  I hope your balancer idea work for you, but unless it's the crank, it could potentially make it worse..but I could be wrong

[Plymouthy Adams]

1 hour ago, 4mula-dlx said:

The big answer is if you can make it do it at all at a stand still, you've eliminated the driveshaft, and once driving under load, you now amplify the engine issue because it will transfer through the rest of the driveline.  I hope your balancer idea work for you, but unless it's the crank, it could potentially make it worse..but I could be wrong

I would not say that the driveshaft has been eliminated as nowhere in the description of work were the additional phrase "had it balanced" I did see carefully engineered.

[59bisquik]

That is why the term double cardan ( which generally implies a 3 joint shaft for high angle)  caught my eye. A double cardan does not set up the same as a 2 joint shaft. Could be the source of vibration.

[Plymouthy Adams]

in overall long length and sharp angles does the double cardan come into play as effective against vibrations due to only the operational limits of the shaft as applied to the velocity and ironing out the excessive angle....there application is not a substitute for balancing the assembly...however, once balanced, normal maintenance with OTS replacements should not alter the balance

[NiftyFifty]

On September 18, 2016 at 9:06 PM, PT81PlymouthPickup said:

After restoring this truck many years ago it had this vibration. I thought then possibly the drive shaft?  I recently have made many changes. Replaced transmission with a Borg Warner T5, new differential with 3.73 gear, brand new drive shaft with a double cardan cv u joint. Runs and shifts great, but still vibrates on acceleration. So, I've pretty much narrowed it down to the engine. I can get it to vibrate a little by revving in neutral, but it seems more pronounced when driving. I rebuilt this engine about 30 years ago. We bored it and replaced pistons with new. All other components were in good condition. All new bearings and valve grind of course. It's been so long, I can't remember weighing the pistons, however I'm fairly sure I would have. This truck has not been used hardly at all over the years having racked up only a couple thousand miles. It's not bad enough to warrant a tear down, which is why I'm considering the harmonic balancer. It's a bit of a project to do correctly, but I'm  guessing it won't hurt anything? I should have been more articulate about when this happens (rpm, which gears, etc.). I'm fairly sure it does it in all gears. Right now I'm replacing the water pump so, I figured this might be a good time to install a damper?

He says it will vibrate at a stop, so that doesn't read like a DS to me, but maybe we are looking for multiple issues.

[Plymouthy Adams]

I got caught up in his stating how he went to the driveshaft himself to source the vibration....should maybe have read more of the thread....that custom made disc could be suspect as could any of the steps along the way in the conversion...