Driveline geometry help... - The 1947 - Present Chevrolet & GMC Truck Message Board Network

FLYNAVY30 · 06-12-2014, 03:13 PM

I have the engine installed using CPPs tubular motor mounts and a crossmember from BMR Hot Rods on the 4L60E trans. Right now, the driveline angle is -9 degrees. From what Ive ready, I want to be somewhere between -3 and -5 degrees. Any thoughts on options? I was thinking of just adding a metal shim to two to the poly mount on the crossmember to raise the tail end of the transmission up a bit as theres plenty of room in the tunnel. Any input would be greatly appreciated.

Thanks!

solidaxel · 06-12-2014, 03:31 PM

Where is the rear end sitting now 2-3 or 4* up?
From what I have read should be +/- 1* difference, shims under the rear mount should work

BR3W CITY · 06-13-2014, 12:23 AM

Where are you measuring from? -9 down would be kinda steep, you sure you're on a level plane?

crazy longhorn · 06-16-2014, 06:06 PM

Quote:

Originally Posted by BR3W CITY

Where are you measuring from? -9 down would be kinda steep, you sure you're on a level plane?

2nd that....set the chassis level, then start the read? You should be 3-5 degrees on the engine/trans (closer to 3, if you can)

read the rest of the angles, from there.... Longhorn

FLYNAVY30 · 06-16-2014, 07:09 PM

The truck is sitting on the concrete slab in the garage, which I checked with a 3' level and is almost dead on. I used one of those dial indicators and set it on the top of the intake manifold (without the carb installed obviously) and got -9 degrees. The only thing that I can think of is that those tubular CPP mounts sit a little higher than the factory pieces? That being said, the front is riding a bit high as the weight savings from the aluminum LS motor replacing the iron big block. I suppose the best way to do this is to level the truck on jack stands on the frame, and measure from there, that way you take the suspension out of the equation?

Thanks for the input!

BR3W CITY · 06-17-2014, 12:33 AM

Quote:

Originally Posted by FLYNAVY30

I suppose the best way to do this is to level the truck on jack stands on the frame, and measure from there, that way you take the suspension out of the equation?

Thanks for the input!

Not the best way, the only way that works! Suspension, wheels and tires, changes to frame or dropmember etc....all that stuff will take away any hope of an accurate reading with the truck on the ground.

Level it on stands, then try your measurement from the manifold again. I did it off the valley, but as long as the intake is square/level, it should be ok to measure from there.

littlevictories · 06-17-2014, 11:22 AM

yeah man 9* is a lot. the engine perches would have to be raised like ~2" by my math to get to there from stock

06-12-2014, 03:13 PM	#1
FLYNAVY30 Registered User Join Date: Apr 2013 Location: Austin, TX Posts: 592	Driveline geometry help... I have the engine installed using CPPs tubular motor mounts and a crossmember from BMR Hot Rods on the 4L60E trans. Right now, the driveline angle is -9 degrees. From what Ive ready, I want to be somewhere between -3 and -5 degrees. Any thoughts on options? I was thinking of just adding a metal shim to two to the poly mount on the crossmember to raise the tail end of the transmission up a bit as theres plenty of room in the tunnel. Any input would be greatly appreciated. Thanks!

06-12-2014, 03:31 PM	#2
solidaxel Registered User Join Date: Dec 2002 Location: Cactus Patch So. Az Posts: 4,749	Re: Driveline geometry help... Where is the rear end sitting now 2-3 or 4* up? From what I have read should be +/- 1* difference, shims under the rear mount should work __________________ 53 TuTone Extended Cab 350 4-Spd 3:08 (SOLD) 53 Chevy Moldy pearl green ZZ-4 4L60E 9" 3:25 55 GMC 1st Black Mll (ZZ4) ZZ6 TKO 600 5 sp 3:73 62 Solidaxle Corvette Roman Red (327 340hp 4spd 3:36) C4 & C5 suspension tube chassis LS 3 4L70E 65 Corvette Coupe 327 350hp 4spd 4:11 78 Black Silverado SWB (350/350) 5.3 & 4L60E 3:42 2000 S-Type 3.0 (wife cruiser) 2003 GMC SCSB 5.3 4L60E 3:42

06-13-2014, 12:23 AM	#3
BR3W CITY meowMEOWmeowMEOW Join Date: Sep 2009 Location: MKE WI Posts: 7,128	Re: Driveline geometry help... Where are you measuring from? -9 down would be kinda steep, you sure you're on a level plane? __________________ *'66 Short Step / SD Tuned / Big Cam LQ4 / Backhalfed /Built 4l80e / #REBUILDEVERYTHING* MY BUILD THE H8RDCPTR //\\ MY YOUTUBE CHANNEL REV J HD

06-16-2014, 07:09 PM	#5
FLYNAVY30 Registered User Join Date: Apr 2013 Location: Austin, TX Posts: 592	Re: Driveline geometry help... The truck is sitting on the concrete slab in the garage, which I checked with a 3' level and is almost dead on. I used one of those dial indicators and set it on the top of the intake manifold (without the carb installed obviously) and got -9 degrees. The only thing that I can think of is that those tubular CPP mounts sit a little higher than the factory pieces? That being said, the front is riding a bit high as the weight savings from the aluminum LS motor replacing the iron big block. I suppose the best way to do this is to level the truck on jack stands on the frame, and measure from there, that way you take the suspension out of the equation? Thanks for the input!

06-17-2014, 11:22 AM	#7
littlevictories Registered User Join Date: Dec 2013 Location: Portland, Ore. Posts: 348	Re: Driveline geometry help... yeah man 9* is a lot. the engine perches would have to be raised like ~2" by my math to get to there from stock



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