Question about LS motor mounts!! I have a problem, Look inside

[Steve Cole]

So I put my 2005 5.3/ 4l60e in yesterday and ran into a snag. Two questions: my engine is tilted back about 7 degrees. Is this too much? I know about three degrees is pretty much the "gold standard" everyone aims for but will I have problems with this setup? I am using the ECE clamshell type LS motor mounts with their transmission crossmember as well. I am also using the CTSV oil pan and I have ample clearance above the engine crossmember. I cannot shim the back of the transmission because it is 1/8" away from the tunnel pinch weld seam. I called ECE and they said this is pretty standard for their mounts. He suggested I convert to a high hump tunnel. ( I am not going to do that!). I told him I would never have bought their kit if I had known the severe angle it puts the motor.

Has anyone else ran into this issue? What did you do about it? Suggestions?

Thanks.

[mongocanfly]

The "gold standard" you need to aim for is to match your rear diff pinion angle....whatever it is your trans tail angle needs to match it..just opposite....trans in neg degrees....diff in pos degrees.....-3 To +3...or close...

[sprint_9]

Mine is at 6 degrees down. Im using squarebody clamshells retrofitted into a 72 frame, so more or less the same design I think.

I agree with Mongo, check your pinion angle before you change anything else. You might be right where you need to be, or closer to what you need. My pinion started at 9 degrees up, I shimmed it 4 degrees down to get it to 5 degrees up. This got both angles within about 1 degree which is what you want. It also makes a difference on your angle split if you are running trailing arms or leaf springs. Trailing arms you should have 1-2 degrees down on the pinion when compared to the transmission output shaft, leafs are more, not sure on the number though.

[Steve Cole]

Hi guys,

I forgot to mention I have the trailing arm rear end, not the leaf springs. I understand that the angles need to be equal but opposite (-3 at the tranny and +3 at the rear for example) but if I am -7 down at the tranny, can I rotate the rear that much up? I thought the area where the axle tubes attach to the trailing arms would not allow that much movement. See pic I stole off the internet.

Also, what mounts are others using and how many degrees down does your engine sit? I am wondering if I should go with a different mount.

[sprint_9]

Something I need to elaborate on that I forgot to mention last night, but you also need to check is the driveshaft angle, your driveshaft angle in relation to your trans and pinion angle, this is where you want a 1-2 degree difference. On the pinion you want your angle to be to the negative, so pointing down in relation to the driveshaft angle.

So as an example. 7* down on trans, say driveshaft is down 6*, you want pinion pointing up 5* This gives you 1 degree on each joint and each one is opposite of the other so they cancel out.

You can get something like this to change your pinion angle. They make them in different angles to get you within a couple degrees.

[Steve Cole]

Okay, first off, thank you guys for your help on this, much appreciated.

Now, I measured the differential last night using the flat face of the yoke where the U joint connects. I got 5* up. I have 7* down at the back of the tranny so I may be in good shape there according to Sprint.

For the driveshaft in this situation, should I expect 6* down, due to the angles of the other two? Once both ends of it are connected, it is what it is right? Meaning there is no way to change the driveshaft angle unless either the angle of tranny or the rear differential changes.

If this is the case, 7* down (tranny), 6*down (driveshaft), and 5* up (differential), is this the ideal situation?

By adjusting my motor mounts forward, I might be able to get the tranny to 6*, is it worth doing, or should I leave it as is?
Thanks.

[sprint_9]

Driveshaft angle will be dependent on the difference in height of the transmission when compared to the rear end. An example being, a stock truck would have more driveshaft angle then one that is lowered 6 inches. Lowering 6 inches brings the rearend up to being more inline with the transmission.

Because of this its best to check it at ride height.

[J3rm0ff]

Here is a picture of my engine mount. Best pic I could get and I couldn’t figure out how to send it thru messages.

[68c10airstream]

[QUOTE=Steve Cole;8313309]Okay, first off, thank you guys for your help on this, much appreciated.

Now, I measured the differential last night using the flat face of the yoke where the U joint connects. I got 5* up. I have 7* down at the back of the tranny so I may be in good shape there according to Sprint.

For the driveshaft in this situation, should I expect 6* down, due to the angles of the other two? Once both ends of it are connected, it is what it is right? Meaning there is no way to change the driveshaft angle unless either the angle of tranny or the rear differential changes.

If this is the case, 7* down (tranny), 6*down (driveshaft), and 5* up (differential), is this the ideal situation?
Hi Steve, I may be the only one to do this but i noticed many ls swaps with slider plates and oem mounts and the engines looked "nose up". So i made my own adapter plates to use the organ donor ls mounts. I removes the cross member braces that go up onto the top of the frame (headers don't hit anything this way) and after installing the F body oil pan and have it layed down about 1/2" away from the cross member i made my brackets. I finished my ford 9" change over and just checked my crank angle and pinion angle and they are; engine at 4.8 degrees up, and rear end (trailing arms) is 2.2 degrees up. I used my wood working expensive angle finder and i've had my truck at 100 mph many times with no vibration at all.
Not trying to say slider plates are wrong, just seemed to be nose up, and i love to fab stuff up. I was really surprised how even the freewheeling clutch fan lined up with the 68 shroud modded up to a 2001 radiator. Radiator core support did get notched to use the wide 2001 radiator.

[Steve Cole]

Thanks for posting Airstream! If I understand you correctly, your situation is directly opposite of the norm. That is very interesting that your engine would be "nose down" meaning the tranny output shaft is greater than 90 degrees? I have not heard of this situation before. What is your drive shaft angle? Is it positive or negative? Thanks for sharing!

[Steve Cole]

Originally Posted by J3rm0ff

Here is a picture of my engine mount. Best pic I could get and I couldn’t figure out how to send it thru messages.

Hi, that is obviously a homemade bracket, what angles do you have for the engine, driveshaft, and rear end?
Thanks!

[68c10airstream]

Both engine and rear end are nose up. With the engine at 4.8 and the rear at 2.2, i'm running about a 2.5 degrees difference between the two. U joint life will be the indicator of trouble in the future.

I installed my engine low and rearward as this is a nascar/handling approach. The "F" body pan was a key element in this as it's very thin under the front portion of the pan. My only issue to date is the fact that the front sump 90 degree corners touch the backside of the cross member at times so i notched it out for the time being until i pull the motor and tidy it up.

Next time i pull the motor i'm going to possible modify my cross member to accept the stock low slung trailblazer ss a/c compressor.

P.S. i corrected my above post to read the pinion angle is nose up at 2.2 degrees, sorry for the confusion.