How to: T56 Magnum Quicktime bellhousing dial-in

[mrennie]

Greetings!

This forum has been a great resource for me and led me to go with a T56 Magnum in my 1970 GTO Judge resurrection. I wanted to return the favour and share some information, so hopefully this "how to" helps others with dialing in their bellhousing.

Like others, I am installing a T56 Magnum using a manual clutch linkage Quicktime conversion bellhousing. In my case I am using the Pontiac/Buick/Oldsmobile bellhousing, but this info should also apply to those using the SB/BB Chev bellhousing.

Quicktime advertises that their bellhousings are very accurately made, and some folks on various forums have said that dialling them in is not required. However, considering the $$$ invested in a new T56 Magnum, I wanted to make sure, and I'm glad I did.



Follow along as I show how and what I did to get it dialled in.

[mrennie]

Here is a picture of a manual clutch linkage Quicktime bell, with some notes I added. (I stole this picture from another forum post here as I forgot to take a pic of my own bellhousing!!)

As you can see from the picture, there is no continuous circular area that is suitable to use as a dial-in surface. Another issue I found was that the opening was cut with either a CNC torch or plasma cutter, and while it is very circular, it is also very rough making it a poor surface to indicate from.

Finally, the T56 Magnum uses dowel pins at the 2 and 10 o'clock position to locate the transmission to the bellhousing, so indicating or trying to centre the round opening in the bellhousing inline with the crank does NOT guarantee that the transmission input shift will be aligned.

[mrennie]

IMO, the only way to ensure the trans will be properly aligned is to use the front cover of the trans itself and indicate from the input shaft bearing bore. This may sound like a big deal but it is actually pretty straightforward.

The first step is to loosen the plug that compresses the detent roller spring. It is located at the very top of the front cover.

[mrennie]

Remove the plug and the spring and set aside. Note that if you do not remove these first, you will have difficulty taking off the front cover, as the shift rail will be pulled forward as you try to remove the cover.

[mrennie]

Remove the 11 front cover bolts using a 15mm deep socket. Once they are all removed you can now tap the front cover off using a plastic hammer (no steel or brass hammers please!!)

Go around the front cover and tap in several places to break the silicone bond. Note there is a dowel pin at the top and bottom of the front cover to locate it into the main case, so gently wiggle the cover to remove it.

Once the cover is off you will see the inner workings of the mighty T56 Magnum!

Cover the front of the trans case with a clean garbage bag or towel, to prevent dirt from getting inside!!!

Also attached is a picture of the shift rail to show where the detent roller rides.

[mrennie]

Next step is to remove the input shaft bearing race and shim. On my trans it was a simple slip fit, requiring nothing more that finger pressure to pull it out. Ensure you keep the outer race and shim together and put them aside in a clean rag or plastic bag to keep them clean.

Cover the remaining holes on the front cover with masking tape to keep dirt out while you are using the cover to dial-in the bellhousing.

[mrennie]

You can now attach the front cover to the Quicktime bellhousing and use it to check the alignment. The most challenging thing at this point will be to get your indicator mounted and setup. This may be difficult as your magnetic stand will have to fit through the oil seal and then you will have to arrange your indicator to sweep the bearing bore. Here is a picture of my setup.

[mrennie]

One thing you will have to watch out for as you rotate the crank, are the 2 notches cutout in the front cover bearing bore (shown below). If you allow your indicator plunger to fall into either notch, it will skew your readings and you will have to start over.

What worked best for me was to have a helper turn the crank using a breaker bar on the balancer bolt, and as the indicator approached the notches i would gently pull the plunger up and away from the bore until the tip cleared the notch, at which point I would lower it back down. As long as i was gentle my readings were repeatable after checking several times.

[mrennie]

After several revolutions I found the point farthest away from the crank centreline and set my indicator to "0".

[mrennie]

Next, I rotated the crank to find the point closest to the crank centreline. In my case the total runout was .026" or +/- .013".

Tremec recommends +/- .005" maximum, so clearly I was out of spec.

My main saddles did have a minor line hone to true them up, but nowhere near .013" was removed, so that does not explain the offset.

The offset could actually be caused by a number of things:

-the location of the engine block dowel pin holes in the bellhousing;

-the location of the transmission dowel pin holes in the bellhousing;

-the location of the dowel pins in the transmission front cover;

-the location of the input shaft bearing bore in relation to the front cover dowel pins.

In any event, my setup was not concentric and this is exactly why i chose to indicate off the bearing bore!!!

[72BBSwinger]

I used the hole in the bellhousing and it has worked flawlessly. I thought the opening was concentric with the bellhousing pattern?

[mrennie]

So, knowing I was out .013", next step was to purchase some offset dowel pins for the engine block.

RobbMc makes some great products, and offset dowel pins are among them.

They make pins with .007", .014", and .021" offsets. The .014" offset looked like what I needed so after a painless online order and a week or so of waiting, they arrived.

Below is a picture of them installed with the offset pointing in the direction that I wanted to move the bellhousing.

http://www.robbmcperformance.com/products/dowels.html

[mrennie]

After installing the offset pins, I swept the bearing bore again and found the total runout was .003", or +/- .0015". This is well within the spec Tremec is looking for.

[mrennie]

Now that it is all aligned, its time to put the front cover back onto the main case.

First step, clean the front cover and ensure there is NO dirt anywhere.

Wipe out the bearing bore and ensure is it clean.

Reinstall the outer race and factory shim. They should simply slide in with very little pressure. (If the race is not straight in the bore it will bind, so be gentle.)

[mrennie]

Remove the old silicone from the flange of the main case and the front cover.

[mrennie]

In order to slip the front cover over the shift rail detents, you will need to push the detent roller up out of the way.

In this picture it is still too low. Insert a small screwdriver and pop it up until it clears the hole.

[mrennie]

After wiping the front cover flange and main case flange with brake cleaner, apply a thin bead of black silicone.

[mrennie]

Install the front cover and reinstall the 11 bolts until they are finger tight.

Before installing the detent roller spring and plug, you must ensure the roller plunger is aligned properly.

There is a notch on each side of the plunger, and they should be inline with the input shaft.

Once that is done, apply thread sealant to the plug and reinstall the spring and plug.

I torqued the plug to 32 ft lbs, which is a spec I found in a Ford TR6060 manual.

Last step, torque the 11 cover bolts in a cross pattern to 35 ft lbs (also found in the same Ford TR6060 manual).

[mrennie]

That's it!

The T56 is back together, and you have now aligned the transmission centeline with the crankshaft centreline.

Please note that this is what worked best for me, and I am very satisfied with the results. Others may not be comfortable going to this extent to verify alignment, but hopefully I've provided some useful info for those that are.

Michael

[mrennie]

I used the hole in the bellhousing and it has worked flawlessly. I thought the opening was concentric with the bellhousing pattern?

Hi,

It may very well be, and mine may be too...but as I mentioned, you have no guarantee that the trans dowels are perfectly installed either.

I assume that there is a tolerance range on all the parts, and tolerance stack could be an issue too?

While the way I did it was a fair amount of work, I have no doubt about the alignment and will be able to sleep better at night!!!