The importance of measuring bell housing runout.

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Dan Brewer said:
Chrysler thought it was important enough that the bellhousing was line bored with the block when new. Perfect alignment. Anytime machine work is done to an engine, or a bell/engine is changed is when you get misalignment.
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Amazing they used such a process back in those archaic times to make sure the transmission would shift correctly and avoid a warranty claim.
 
I’m planning to swap to a 4 speed this winter. The 5.9 magnum that’s in the car isn’t drilled for the input shaft. I have a spare engine that I tore down on the stand and figured I could use it to get measurements to pre cut the input shaft. Got everything bolted up and my spare was drilled (completely spaced checking it first :BangHead:)
Hoping this old lakewood scatter shield comes out somewhat close when I measure the runout :thumbsup:.
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RustyRatRod said:
I gotta say, I just don't buy that. Just imagine how many millions of vehicles they'd had to do that on. Stop and think about it. That would have cost them a crapton.
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Dan Brewer said:
Chrysler thought it was important enough that the bellhousing was line bored with the block when new. Perfect alignment. Anytime machine work is done to an engine, or a bell/engine is changed is when you get misalignment.
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Well, It looks like the man that owns a well known transmission shop has chimed in. Thanks Dan.
 
skep419 said:
I’m planning to swap to a 4 speed this winter. The 5.9 magnum that’s in the car isn’t drilled for the input shaft. I have a spare engine that I tore down on the stand and figured I could use it to get measurements to pre cut the input shaft. Got everything bolted up and my spare was drilled (completely spaced checking it first :BangHead:)
Hoping this old lakewood scatter shield comes out somewhat close when I measure the runout :thumbsup:.
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Hope your not going to use that threaded rod to indicate the locating bore on the bell housing/ scatter shield. It won’t give you a true reading in that position. Its going to drop cause of gravity. It will give you a true reading if you remove water pump and acessories and set timing chain cover face on the ground level to the bell housing mating face of the block if that surface is perpendicular to the axis of the crankshaft.

The farther out horizontally you stick an indicator, the more it will drop. The hole you are indicating will be off down to the floor from true position. This holds true for a magnetic base as well.

The face in your picture where the trans mounts to the bell housing/scatter shield needs to be shimmed perpendicular to the rotating axis of the crankshaft. This needs to be done before indicating and offsetting the dowels to get the bore on true position.

Trust me on this, I had a 45 year career as a tool and die maker and learned this experience running horizontal boring bars for 30 of those years.

You will find you will have to remove and re-install your bell housing/ scatter shield 4 times to get it dialed in, maybe more depending on how close you want it to be. Accuracy reduces frictional losses.
 
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Nice post from Dan
Its made me think about it a lot more

so that motor where you had to get a shorter timing chain
the one where the rear main seal always leaks, where you had to go back to rope and it didn't quite work out

bet that's also the motor that cracks flex plates or is hard to shift

if its been line bored to any great extent aftermarket main caps or any reason the crank is potentially a few thou closer to the head than it was and that'll mess totally with the alignement of the bellhousing register in relation to the crank

this shouldn't be a revelation to me, its bloody obvious But you know what..... i'm a bit slow....

it also means aftermarket block where the hell is that centred......
i'm sure they all align with each other and that crank will turn like its in butter but.....

if you only do a limited run of 100 or 1000 you are gonna make damn sure they all go out the door for retail sale regardless

Couple that with aftermarket housing well could be half a mile out....

broken starter anyone....

i'm on a roill ... probably time to stop :) 17:30 friday afternoon is time for beer

Dave
 
ch1ll said:
Hope your not going to use that threaded rod to indicate the locating bore on the bell housing/ scatter shield. It won’t give you a true reading in that position. Its going to drop cause of gravity. It will give you a true reading if you remove water pump and acessories and set timing chain cover face on the ground level to the bell housing mating face of the block if that surface is perpendicular to the axis of the crankshaft.

The farther out horizontally you stick an indicator, the more it will drop. The hole you are indicating will be off down to the floor from true position. This holds true for a magnetic base as well.

The face in your picture where the trans mounts to the bell housing/scatter shield needs to be shimmed perpendicular to the rotating axis of the crankshaft. This needs to be done before indicating and offsetting the dowels to get the bore on true position.

Trust me on this, I had a 45 year career as a tool and die maker and learned this experience running horizontal boring bars for 30 of those years.

You will find you will have to remove and re-install your bell housing/ scatter shield 4 times to get it dialed in, maybe more depending on how close you want it to be. Accuracy reduces frictional losses.
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I was just hoping to get close enough so I don't bottom out the input shaft into the crank.
 
Dave999 said:
however the process to both shim and align a bellhousing is in my factory manual
decsribed in a way that makes you mentally i'll....:) covers both auto and manual
they say it must be done if you swap the bell from the orginal one for a manual trans

1971 VH Valiant Australia factory manual... presume others have it as well. chrylser stock photos rather than car specific. i.e numerous LHD photos in a manual for RHD Cars in the suspension and drive train sections

the first post video is prefect for run out...its a great thing
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Now THAT makes sense!
 
My 70 340 4 speed Duster was the first race car I ever built. Back in the 80's. The Lakewood Blow Proof Bell Housing was not aligning with the trans but I eventually got them mated. It made some squealing noises and could not be speed shifted AT ALL. Dick Landy recommended exteding the clutch arm a 1/2 inch but did not help. Most folks blamed it on the pilot bushing in the back of the crank, since I had never even looked for it out of ignorance. This article answers question's I 've had about that for 40 years. THANK YOU ALL!
 
Every since I had to replace a head gasket on my 340 back in 1971 (blew the bypass hose when racing at OCIR) and they had to mill the heads, I learned that machining an engine leads to other issues. In this case, the intake manifold bolts didn't align with the head and it was a PITA to get the bolts installed. FSM say to mill the intake when the heads are milled. And they are right!
So, if you have a block align honed, that moves the crankshaft up in the block by the distance honed off the crank bore. This will change your alignment with the trans, thus the need to align the bell housing.
I also hate boring an engine any more than absolutely necessary. My 340 builds are at most +0.020" if at all possible. Why go +0.030" if it isn't needed. I would go +0.010" if pistons were available. Thicker bores are happier bores and will make more power too.
So, I fully support measuring everything.
 
Go look at your 60's and 70's service manuals from Dodge/Plymouth. There is a whole chapter on aligning bell housings and the importance of it. I have been doing the alignment checks on all my motors I build for over 30 years. Even Ford and GM. The only time I find something way out either face or crankshaft alignment is the aftermarket bell housing. I send them back and get one that will pass. I have a factory small block and big block bellhousings that I use to double check my finding. Also remember when you line hone a block normally you move the crank line .004" to .006" up in the engine and that will put it out of spec. The factory offset (aftermarket) dowel's come in .007, .014 and .021" settings. So if your total is .028 a .014 offset dowel will get you back to center.
 
Ken Imthurn said:
The factory offset (aftermarket) dowel's come in .007, .014 and .021" settings. So if your total is .028 a .014 offset dowel will get you back to center.
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I don't think the dowels are stackable, meaning a pair of .014 dowels will adjust the BH .014" not .028". At .028", a pair of .021" dowels reduce the TIR to .007"; out of spec for a Tremec. I'm the FBBO member that Greg mentioned at the beginning of this thread. The TKX is going in the Coronet and we've had a hell of a time measuring the runout. Not the measuring itself, we've gotten pretty good at setting up the base and indicator and replicating measurements - for the most part. We left last night with the runout at .048" - .024" TIR. A pair of .021" Robb Mc dowels would bring the BH below the .005" spec. We removed the BH before calling it a night.
This morning I reinstalled the BH and measured again just for S&G's, and the runout didn't get any closer than .056" / .028" TIR. I'm lost, and frankly a bit defeated.
 
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Tomorrow morning we're going to bolt up the TKX bell to a 440 that Greg has secured to a stand. If the runout is consistent then we know its the bell. I'm actually more concerned that the bell will fall in spec. That means something is off with the engine.
The engine mating surface has been cleaned and prepped. Initially there was a tiny metal booger, created when something slammed into the side of the engine and dented the mounting flange. I filed down the protrusion and smoothed the surface with crocus cloth.
Next, I found a hairline cut (not a crack) at about 2:00 on the mounting flange. It was a clean cut, but a very slight ridge had built up the length of the cut. Again, it was filed down and sanded smooth. No doubt those two imperfections led to the .082" / .041" TIR measured earlier in the week.
Post prepping of the engine mating surface got the measurement down to yesterday's .048" / .024" measurement. But then today's measurements set the process back to square one.
Dent:
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Hairline cut
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Hairline cut after filing
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Engine mounting surface fully prepped
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Just take all the guesswork out and trust the dial indicator.
 
The bellhousing is a part of the engine like a maincap! Mercedes descripes the same procedure for measuring the runout in their workshop manual, so nothing wrong with Lakewood or Chrysler.
I had also a popping out 4th gear (A833) because of missalignement.
Do your self a favor and correct it.
Marco
 
Since I am not an expert on this, I look at it like I do other projects where I'm learning as I go.
I often wonder if the tough time I am having is the same for others or if I'm making things harder for myself by doing it so wrong.
For example....
In 2021 when I used this dial indicator to measure runout on my own car, I bought a generic dial indicator and magnetic base setup from Summit. It was bulky and clumsy to the point that I couldn't set the gauge face in a way that I could see it.

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The center rod attached to the magnetic base was so long, it was in the way of clocking the gauge to where I could see it. It was difficult but I just figured that was how it had to be.
Yesterday I had the idea to cut back that center rod to end before the opening in the bell. Now, there is room to place the gauge where it can be read easily.

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It doesn't have to be in the crank center hole. You can mount the magnetic base anywhere on the flywheel it will fit. Here's a good video.
 
Thank you.

I was able to get the measurements being off center but the further you go off center, the greater risk of error in the readings.
 
There's no substitute for experience and over the past week I've scaled the learning curve and its finally beginning to flattened out. Back to the task at hand:
Greg took the initiative to drop one of his 440's onto a cart so we could compare runouts. The cast iron bell had almost zero runout, matching the results we measured on the Coronet.
Next, we mounted the SST bell to his block and using his dial indicator, measured .0445" TIR / .022" runout.
Then we remounted the SST bell to the Coronet, and using my indicator measured .045 / .0225. Success!
The bell bore is still far from concentric, but the runout is correctible with .021" offset dowels.
Shop 440, SST bell
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Close up
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SST bell in the Coronet
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Close up
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Didn’t read this whole thread yet… but wanted to reply specific to your mentioning the automatics and front seal leakage and flexplate cracks.

B&M flexplates are supplied with instructions for checking runout and they even say that the flexplate is good for stock to somewhat mild engines… but more then that and it can and probably will crack the plate.

How do I know….. cause I just did it within 500 miles of install. And the front seal started leaking and it got worse and worse….Motor is a 408 stoker with 592hp and 577 torque.

The car has always had a bad pulsating vibration in the trans hump area that started after a front end collision years ago. But it ran fine on the previous flexplate and the front seal didn’t leak.

Everything on the car is new now…even insides of the trans and torque converter. Motor…. suspension (Reilly)… etc…. The only thing left of the car that is the same is the trans case itself (vin matching case) and the rearend housing and axles. Yet still I have the vibration issue. Never could figure it out. Even had the pinion angle checked with the wheel alignment… all good.

My guess is the trans case is worn and while it does fit and mate up with the dowels… it’s not centered well and maybe the dowel holes are wobbled… possibly from the wreck.

The crappy thing is the guts of the trans would have to come out to check it…so I’m going tremec tkx from sst. Hence why I started reading this thread. But I can say… the autos def need to be checked after all these years id say. 53 year old trans case could be bad.

I look forward to reading the rest of the thread. :)
 
So what changed from Fri and Sat to Sunday? The initial .082" TIR was because the engine mounting surface was not smooth and prepped.
After prepping, the second measurement came in at .048" TIR; not great but within spec using a .021" offset dowel.
The reason the 3rd attempt jumped up to .056" was that the passenger side dowel pin came off inside the cast iron bell when it was removed. While reinstalling the SST bell I was fixated on aligning with a homemade dowel pin Greg had crafted and didn't notice the missing pin. Greg found the pin when he bolted the cast iron bell to his engine.
With the pin back in the Coronet engine, we were able to replicate the SST runout between both engines.
Bottom line, I made a bunch of rookie mistakes and oversights. This was my first time using a dial indicator, and was easily the first time I've ever had to measure accuracy down to .005".
As Greg posted earlier, documenting these trial and errors will hopefully help someone else down road as they're reading this.
 
cli55er said:
Didn’t read this whole thread yet… but wanted to reply specific to your mentioning the automatics and front seal leakage and flexplate cracks.

B&M flexplates are supplied with instructions for checking runout
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This confuses me. How do you check runout with an automatic transmission?

cli55er said:
But I can say… the autos def need to be checked after all these years id say. 53 year old trans case could be bad.

I look forward to reading the rest of the thread. :)
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Need to be checked? I do agree, especially after a collision. I'm just curious about how it would be done. If there was some way to measure the runout without complete transmission disassembly, I'd sure like to know.

As for the rest of this story, the original thread for the Tremec install in Rich's Coronet is here:

Tremec TKX 5-Speed Conversion

I also did a Tremec swap back almost 3 years ago. I wrote about it here:

Tremec 5 speed conversion in a 1970 Charger
 
No lol.
Its a circle.

The only variance you will see is deflection in the measuring instrument. One thing that can throw you off is the bearing retainer hole not being perfectly round. That is one of the issues with older lakewood bells along with the horrific alignment problem.

My quicktime bell has a litany of issues that required correction. I have used it on a few different engine and none required more than .014 offset dowels whereas the lakewoods use mostly .024's or whatever Rob sells.

I keep a set of each in stock if that is a good indicator of importance.

My advice is to verify the retainer hole to see if it is concentric and mark any anomalies so you can account for them.

If you need more offset than rob dowels offer you can get an adjustable reamer to slightly open up the alignment holes. At that point you can weld locating washers in place to retain your position.


Kern Dog said:
Thank you.

I was able to get the measurements being off center but the further you go off center, the greater risk of error in the readings.
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