T56 bellhousing alignment - Quicktime

[c4racer2]

I just wrapped up aligning the Quicktime bellhousing for my T56 Magnum install.

Original measurements we 26 thousands off, so used a 14 dowel from Lakewood oriented to move the bellhousing towards 2PM on a clock.
Which ended up pushing it slightly over in that direction - now sitting at 6 thou off too far towards 2PM.
So either need to shave 2thou off the lakewood pins at the 2PM location, or just leave it.
Tremec spec if .005 so it's within .001" of that.

Parallel axis is another question mark - I'm at .004" out on the top.
so either I need to shim the bottom bolts by .002 or leave that alone too.



Thoughts?

[John McIntire]

How did you get a consistent surface to run the dial on? I know Bowler makes an adapter so you have a full circle to run on.

[c4racer2]

I used the Quicktime RM-130 index plate to measure cocentric

For the parallel check I used the bellhousing surface that the trans mounts to as I felt that would be more accurate than the index plate.
There are gaps in that surface but you are really checking mostly top and bottom - in my case the bottom is out .004" so I am going to try to add .004" shims to the top 2 bolts to see if that gets me closer.

Bowler suggested I do that and get the parallel dimension within .002" if possible and said the run-out I have is OK.
I am hoping that the runout will tighten up 1-2 thousandths once I align the parallel dimension. fingers crossed anyway.
If it gets worse I may try removing some of the powdercoating on the bellhousing to move it ever so slightly.
I'm already within the range of what I can do with offset dowel pins.

[charv712]

I am also attempting to dial in my Bellhousing and am having a tough time. I see lots of guys removing the front plate from the T56 and indexing off of the front bearing bore. My question is this...you are going to get vastly different numbers off of checking parallel on the face of the Bellhousing(the part that the transmission mounts to) and even on different numbers on the face of the QuickTime RM-130 index plate. As the diameter of the circle that you’re sweeping gets smaller, generally so do your numbers. That being said, I haven’t read anywhere in an official Tremec, or QuickTime document the Gold Standard location or diameter for taking the measurements. Meaning everyone is taking their measurements at a different circumference, unless they are doing it on the bearing bore of the Transmission front plate. Can anyone clue me in to anything different or some piece of information that will help me to be certain and feel good that my measuring technique is correct? I’ve been using the RM-130 indexing plate, but it has a 4” circumference hole to measure around, whereas I believe the bearing bore is only a circumference if 2.6” or something like that.

[Alponcho]

I too have been messing around with this, and I think my problem is the dial indicator is inconsistent. Any recommendations for a good one and base?

[badazz81z28]

You don’t index the bell-housing for the T56 using the large hole in the bell housing. They now sell a plate to bolt to the bell-housing to assist. Or the alternative is to take the front plate off the transmission and use the dial gauge to read off that small bearing bore.

I have never checked Parallel alignment, even though it’s the full correct method, only concentricity has worked for me over the last 7-8 years.

[ctcz28]

I am also attempting to dial in my Bellhousing and am having a tough time. I see lots of guys removing the front plate from the T56 and indexing off of the front bearing bore. My question is this...you are going to get vastly different numbers off of checking parallel on the face of the Bellhousing(the part that the transmission mounts to) and even on different numbers on the face of the QuickTime RM-130 index plate. As the diameter of the circle that you’re sweeping gets smaller, generally so do your numbers. That being said, I haven’t read anywhere in an official Tremec, or QuickTime document the Gold Standard location or diameter for taking the measurements. Meaning everyone is taking their measurements at a different circumference, unless they are doing it on the bearing bore of the Transmission front plate. Can anyone clue me in to anything different or some piece of information that will help me to be certain and feel good that my measuring technique is correct? I’ve been using the RM-130 indexing plate, but it has a 4” circumference hole to measure around, whereas I believe the bearing bore is only a circumference if 2.6” or something like that.

The diameter of the hole you are measuring needs only to be large enough in which to get your measurement instrument. It does not matter if the hole diameter is 2" or 7 " since you are looking only for the differences in measurements across the diameter as the dial indicator sweeps the circle. The measurement would be easier to make with a larger circle for sure. Unfortunately the index plate was not not available when I made the runout measurements for my T56 installation so I had to pull the front plate from the trans. You'll have a much easier time with the index plate. Do check and adjust the parallel measurement first and do not assume it is within spec. If the parallel measurement is out of spec adjusting it to correct will affect the runout measurement so if you adjust the runout first and the parallel after the fact, you may need to further adjust the runout. If the parallel is off, you're technically measuring an ellipse when you measure the runout.

[badazz81z28]

The diameter of the hole you are measuring needs only to be large enough in which to get your measurement instrument. It does not matter if the hole diameter is 2" or 7 " since you are looking only for the differences in measurements across the diameter as the dial indicator sweeps the circle. The measurement would be easier to make with a larger circle for sure. Unfortunately the index plate was not not available when I made the runout measurements for my T56 installation so I had to pull the front plate from the trans. You'll have a much easier time with the index plate. Do check and adjust the parallel measurement first and do not assume it is within spec. If the parallel measurement is out of spec adjusting it to correct will affect the runout measurement so if you adjust the runout first and the parallel after the fact, you may need to further adjust the runout. If the parallel is off, you're technically measuring an ellipse when you measure the runout.

You need to consider...Is the hole in the QT bell-housing centered with the crank center-line? I don't think it is! You need the center-line of the transmission to be in-line with the center-line of the crankshaft. This is why nobody will tell you to use the LS QT bell-housing hole and proceed to point you to removing the transmission front plate and using the input shaft bearing boss. The SBC was different because the hole in the housing located the bearing retainer and that was/need to be the hole that was centered.

I'm just not a firm supporter of parallel alignment. Granted its the sure way to go if done right....its just that the QT bell housing is powder coated. If you measure the face of that bell-housing, there is going to be error in the thickness of the PC...The only true way is to ensure the measuring surface is flat AND the transmission face is actually flat too (remove PC and machine surface flat)....Essentially 3 surfaces need to be flat to be accurate for when the assemblies are all bolted back together. If the transmission face isnt perfectly flat then all your measurements and adjustments of the bell-housing are null. If I was looking to maximum performance, I would pay to have the block/bell-housing precisely machined flat.

[charv712]

For anyone who shimmed their Bellhousing to achieve parallel alignment, how thick were the shim thicknesses you used and where did you place your shims? I’m having a hard time getting accurate adjustments using my shims. For example, my furthest in(negative) reading is at the 3 o’clock and 9 o’clock position at about -.003...my most positive reading is at the 6 o’clock position at about +.0020...when I shim the sides to correct for the negative issue, it pushes the bottom out even more positive. Am I doing something wrong? If not, what should I then do in order to bring my numbers closer together?(that’s the main idea right?) thanks for the help

[charv712]

My numbers are as follows...

Starting at 0 in the 12 o’clock position
-.003 in the 3 o’clock and 9 o’clock positions
+.002 in the 6 o’clock position

I thought I was supposed to bring out(shim) the most negative number first and then dial in the rest a bit at a time. Is this correct? Can anybody give me a detailed run down on how to go about fine tuning the parallel? As I understand, I’m supposed to do this before moving into concentric, but have been messing around with this for too many weekends and have been unsuccessful thus far. I’m trying to get all readings within .002 as pointed out by Jody, but have not been able to. I just keep chasing my tail. I have cleaned off the front and back surfaces of the Bellhousing. There is no powder coating, it’s down to bare metal. I have numerous shim thicknesses varying from .001 up through .03 available. Again, thanks for any help in advance.

[c4racer2]

I did parallel after the runout. Should have done it first. I had to redo the runout.

For parallel I used .005” Shims and I got it pretty dang close. Within 1-2 thousand
But you have to measure it. I was off .01

[charv712]

Thanks for your response. Did you add shims all around? At each of the top 6 bolt holes? Is your setup in the car? Or out? Do you have any pictures? My problem is when I try to add shims to the 3 o’clock and 9 o’clock positions in order to bring them from negative to neutral, or positive, it also stacks that added shim amount to my 6 o’clock reading, making it even more positive. I’ve then tried adding some shims to the top in order to level out the top and bottom, but adding to the top seems to take away from the 3 o’clock and 9 o’clock! It’s a mess. Is there any kind of scientific way or tried and true method to this shimming? If so, what is it? Any suggestions?

[c4racer2]

Just top 4
It’s in my car now. It wasn’t when I did all that.

[c4racer2]

For parallel alignment you are just measuring 12 and 6.
But I get what you are saying it can and does change the runout
I ended up with about .008 total runout and parallel about .001 and my trans guys were satisfied with that combo.

[charv712]

What do you mean by total runout? And wouldn’t the circle potentially be off if you only focus on the 12 and 6 o’clock positions?

[badazz81z28]

What do you mean by total runout? And wouldn’t the circle potentially be off if you only focus on the 12 and 6 o’clock positions?

i don’t see how you could just focus on 6 and 12. To do it right, you need to check 3-9 and in between. Also any adjustments you make to one side will affect the other.

[ctcz28]

Are you making the parallel measurements with all of the BH bolts installed and torqued to spec?

[charv712]

Yes, I am torquing all bolts to 35 foot lbs. each time I make an adjustment.

[c4racer2]

i don’t see how you could just focus on 6 and 12. To do it right, you need to check 3-9 and in between. Also any adjustments you make to one side will affect the other.

Yes true. 3 and 9 were not off in my case.
Correcting the 12 to 6 difference made it even all around on the parallel alignment.
For my install anyway.

Total runout on concentric is the max difference you read on the dial indicator around the whole circle.

[ctcz28]

Are you also installing the backer plate when you do these measurements? Torque to 35 lb-ft should be more than sufficient since I think the spec is 25. If I understand your measurements, it appears your block has a dip, i.e., is concave at 3 and 9 and has high spots, or is convex at 12 and 6; this is a stinker if that's the case. If you put a 0.001 shim at 3 and 9 and none at 6 and 12, will the 3 and 9 go to -0.002 and 12 and 6 stay the same or do the 12 and 6 to to 0.003??