Transmission Hump - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Rat72 · 12-15-2009, 02:47 PM

Can someone tell me why the 4WD trucks have a hump in the transmission tunnel where the 2WD units are flat? Is the engine higher or further back on 4WD trucks. I'm building custom engine and tranny mounts for a LS2 setup in my 4WD truck but I kinda like the flat floor on the 2WD trucks. Seems like it would be easy to drop things down enough to clear the 2WD tunnel.

Thanks.

Jacfourteen · 12-15-2009, 02:56 PM

4wd trucks have the engine mounted further back in the bay, also I think the transfer case needs additional clearance. The 2wd with floor shift also have high hump because the shifter cover is bumped up so the hump needed to be higher. If you mount the engine in the forward position and use an automatic you may be able to use the small hump. I'm not sure how mounting the engine in the forward position will affect front driveline angle though. You will prob just have to measure it out and see what you can do. Good luck.

Rat72 · 12-15-2009, 03:25 PM

The transfer case is definately an issue. With the engine in the stock position I have to tilt the whole thing back by 6 degrees to clear the transfer case. It does not hit the tunnel, it hits the crossmember right behind the tunnel. With the short driveline and lift the driveshaft angle is almost 20 degrees. I'm thinking that I can drop the front down and get the engine to 1 degree, the driveshaft angle will drop to 15 degrees.

Or I could put a body lift in but I just took out the 3" body lift it came with.

12-15-2009, 02:47 PM	#1
Rat72 Registered User Join Date: Sep 2006 Location: Portland Posts: 135	Transmission Hump Can someone tell me why the 4WD trucks have a hump in the transmission tunnel where the 2WD units are flat? Is the engine higher or further back on 4WD trucks. I'm building custom engine and tranny mounts for a LS2 setup in my 4WD truck but I kinda like the flat floor on the 2WD trucks. Seems like it would be easy to drop things down enough to clear the 2WD tunnel. Thanks.

12-15-2009, 02:56 PM	#2
Jacfourteen Big Red - Now its a SWB! Join Date: Jun 2009 Location: Oroville, Ca Posts: 1,624	Re: Transmission Hump 4wd trucks have the engine mounted further back in the bay, also I think the transfer case needs additional clearance. The 2wd with floor shift also have high hump because the shifter cover is bumped up so the hump needed to be higher. If you mount the engine in the forward position and use an automatic you may be able to use the small hump. I'm not sure how mounting the engine in the forward position will affect front driveline angle though. You will prob just have to measure it out and see what you can do. Good luck. __________________ 68 3/4 ton (Project)-350 Small Block, .030 over, 10:1 comp, 3998993 heads, C3BX edelbrock intake, comp cams XE268, Holley 670 SA, long tube headers, dual flow 40's, E-fan, Alum rad, currently under the knife getting shortened and bagged build thread 41 3/4 ton (wife's)-flatbed, fully restored to original 01 Tahoe LT 4WD (my daily driver)-Magnaflow Muffler, Rollin on 22's 02 Ford Mustang Convertable (Wife's Car)-Flowmaster 50, Clear corners, Intake, sittin on 18's

12-15-2009, 03:25 PM	#3
Rat72 Registered User Join Date: Sep 2006 Location: Portland Posts: 135	Re: Transmission Hump The transfer case is definately an issue. With the engine in the stock position I have to tilt the whole thing back by 6 degrees to clear the transfer case. It does not hit the tunnel, it hits the crossmember right behind the tunnel. With the short driveline and lift the driveshaft angle is almost 20 degrees. I'm thinking that I can drop the front down and get the engine to 1 degree, the driveshaft angle will drop to 15 degrees. Or I could put a body lift in but I just took out the 3" body lift it came with. Last edited by Rat72; 12-15-2009 at 03:27 PM.



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