Engine -Rear alignment

[LZ]

Hi Roo:
Say a question for you and hopefully this will be some good info for our friends here also.
Disclaimer.  I am not good at putting thoughts to words and am sorry for any misspelled words or Grammar. Tried to sumize this as much as possible. Dimensions taken with cold gloved hands. LOL
Of info:
Bought a 2010 S&W 225” FED a few months ago. It had a BBC and glide set up. 9“ with a 12 bolt center section. Motor out 43”.
I am putting in a little whale with a glide behind.
To get a good baseline start on making a new engine plate. Figured to check the car as it came. I took a Chevy block and put it into car with original engine plate. Have a pc of 2 “ TGP shafting for an alignment bar. The rear is all set up and just figured to see how it measured off the coupler on rear.
Upon getting it all together slid the shaft back to the coupler and could see its visually off.
Over the last few days upon getting home from work have measured  as many ways as I could to get a good set of data points. Try to get figures to back others up. Also check by loading weight to chassis to see what influence that may have had. Also if another way to check came to my simple brain given some time to ponder it.
Also I was able to get a few minutes on the CMM at work to check the Engine plate in car now to get good baseline numbers with relative from the engine dowels to the frame rail saddle. Was surprised that the Dowels Datum plane with relative to the saddle in hight dimension were within less the .003 “ at local and the side to side dimension, (er to speak the dowels , relative to crank CL) was within .002 at local. It is a water jetted Ό 6061 plate.

Here seems to be my numbers that I have some reasonable confidence in.
With looking down at car with the front to your right. The shafting was visibly closer to you in relative to the coupler. Or in other words, looking straight at rearend, the shafting is to the left relative to coupler..
Measurement :
Again looking down at car with front to your right.
Shaft to coupler  .15-.16 TIR or .075 off Coaxial in side to side. Towards you.
Measured shafting at front of engine to upper frame rails. .12 TIR or  .06 Coaxial side to side towards you.

Looking straight on towards side of car, with relative to horizontal. The shafting was within less than .010 TIR at coupler. With the shafting coming in at an angle relative to pinion CL. Measured with a 16 inch parallel it showed the shafting aligned towards ground roughly  .015 in that distance.
This is not a good explanation sorry. If Im doing my trig correct its about .05 degrees.  I know its small but just trying to give you all the dims.

Notes:
 - I tried to back numbers up measuring different ways
 - I did not do a repeatability check on rear to see how much it varies per install.
 - The part the gets my face in a squinch is….By these numbers it seems I need to move the engine by about a 1/16th BUT…. The engine plate shows it in very good numbers centered to chassis in relative from the engine dowels to the top rails saddles from the CMM data??. When I checked the engine plate did  not expect to see what we see once in car.
 - In other mention also this car as said has a 12 bolt center section. I do not have a spare center section. Only way I could put shafting with a bushing on the center section is to take the gears out which I  did not think would have needed to do.
 - The rear is mounted well.  The only way I could see it moving a bit is if there is some slop in the bolt holes, but this only changes the the radial (relative to axle datum) angle
Questions:
 - My goal when I started this was to reaffirm the alignment so that I could use the chevy dowel s as a baseline to put the hemi pattern into the new plate. Was this out of line thinking?
 - What kind of tolerance would I be looking at or is in good practice?
 - The Couplers that were run in car are in excellent shape. The one only shows a little more rub on about half of spline, mostly even contact. With other end showing even contact. Did not check as to which side was in the tranny and which to rear. Just thought of that..
 - Was thinking that when fabbing the new engine plate to offset the engine CL by .065 - .070 “. From the position it is now.

I know your time is very valuable and I appreciate any input. 
thank you very much
Luke

[dreracecar]

Some chassies move after set-up and welding, some move after running or just by age alone. If the previous owner ran a shorty glide, prob did not notice the mis-alinment because the couplers had enough slop to compinsate.

 Take your 2" TPG bar and either turn one end to a point or drill and tap for a bolt(end turned to a point) and re-install your third member and line everything up to the drill center that the end of every pinion has when they make them. Now with that line-up indicater inplace, use some sheet metal as shims to move the pointer around till you hit the drill center.  A thin shim at the motorplate moves the line up a bunch from that far away. From that point you can decide "IF" you can just shim the plate to the chassie,or move the tabs and you are going to wind up making new front mounts anyway

[rooman]

Thanks Bruce,
                      I have been working away from my shop and am not getting on here as much as usual. I agree that the amount of mis-alignment that Luke is talking about is probably well withing the limits of what most coupler packages will allow. Shimming to correct sure won't hurt either.

Roo

[LZ]

Some chassies move after set-up and welding, some move after running or just by age alone. If the previous owner ran a shorty glide, prob did not notice the mis-alinment because the couplers had enough slop to compinsate.

 Take your 2" TPG bar and either turn one end to a point or drill and tap for a bolt(end turned to a point) and re-install your third member and line everything up to the drill center that the end of every pinion has when they make them. Now with that line-up indicater inplace, use some sheet metal as shims to move the pointer around till you hit the drill center.  A thin shim at the motorplate moves the line up a bunch from that far away. From that point you can decide "IF" you can just shim the plate to the chassie,or move the tabs and you are going to wind up making new front mounts anyway

Hi Bruce:
Yes I missed mentioning that sorry. It does have a shorty Glide with a Solid Drive shaft - coupler at ends deal.
Its funny to me (being in Mfg.) that over the years when working on these , a Dragster or Altered and such. That there beauty in there simplicity but I always wonder whats going on when they make a run. Especially in the drive line alignment. It would be fascinating to take something , put some strain and some linear motion gauges on it. See what is happening. And of course every car and combination would be different.  With the short shaft and couplers at each end we have a bit of compliance.
Just trying to make sure to get this car set up as best possible and thank you for your time.
Ready for the MM?

Thank you
Luke

[JeffV8]

Rooman
Finish that job up already lol 

[janjon]

I had to google TGP. 'Round here we use PSQ. "Pump Shaft Quality". Similar thang, I expect..

[rooman]

Rooman
Finish that job up already lol 

Jeff,
      I am putting cages (and other stuff--fuel cells etc) in three brand mew Mini Coopers that will be running in the Continental Tire Street Tuner class with IMSA. I have one mostly done and started on the second yesterday. I am doing them in the team's shop because they are working on the rest of the car but I am also having to hold their hands on some of that stuff too. I need to add a consultancy fee to the bill.   

Roo

[dreracecar]

TGP stands for turned-ground-polished and not to be confuzed with "Drill Rod" which is expensive and NOT ROUND!!

[PSweeney]

an old hydraulic ram is a cheap option for a line up bar.