Longer transmission and moving mounts - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**WestButteTruck** · 03-23-2021, 03:22 PM

So, did some searching, not finding what I was looking for. Anyway, I am swapping out the TH350 for the 4l80E. This is in a 1972 LWB Chevy 4x4. With the new transmission length, I need to make up around 4-1/2 inches. Was thinking of setting the transmission and transfer case mount back around 3 inches and moving the engine forward 1-1/2 inches. I'm sure someone has done this and has a recommended setup. I would like to gain a little bit of firewall room. Thanks

**WestButteTruck** · 03-23-2021, 08:15 PM

I thought I would add that the engine is a 400 sbc and I hope to keep the stock radiator, shroud, possibly fan, etc. Probably just need to find out how far forward moving the engine is too far without running into issues?

**kwmech** · 03-24-2021, 11:08 AM

Move the front motor mount cross member forward to the next hole found on the drivers side. You'll have to drill the frame on the right (this is a good time to upgrade to 7/16 bolts) This places the engine in about the 2wd position. So for ease, you'll need a 2wd fan shroud, 2wd upper and lower radiator hoses and a 2wd throttle cable. Underneath at the trans-- drill holes where needed. You'll have to modify the floor pan for the 4wd shifter

Forgot also that there will need to be a little fabrication on the automatic linkage to the trans. The pivot will have to be modified moving it closer to the leaf spring shackle. Been a couple years since I did a T400 in a K5

**WestButteTruck** · 03-24-2021, 04:16 PM

Thanks for the info, I appreciate it!

79vette · 03-25-2021, 11:14 PM

I added a Ranger overdrive in my K5 (like a stick shift version of a Gearvendor that goes in front of the trans). I did not want to deal with moving the engine, checking fan clearance, etc and just moved the transfer case crossmember back ~7" and drilled the frame to match. Left the engine in the original position.

This is what the drivetrain looks like from the top. If pics of the relocated crossmember would be useful I can put some up tomorrow.
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Name: IMG_20200208_180504.jpg
Views: 114
Size: 92.7 KB

Bigdav160 · 03-26-2021, 07:20 AM

I did a 700R4 and moved the engine forward.

My stock 4x4 fan shroud would not work without cutting. I instead made one out of aluminum.

My exhaust also interfered with the motor mount/crossmember and required a little bit of grinding but I am running aftermarket Tru-ram manifolds

03-23-2021, 03:22 PM	#1
WestButteTruck Kung Fu Master Join Date: Oct 2005 Location: Montana Posts: 543	Longer transmission and moving mounts So, did some searching, not finding what I was looking for. Anyway, I am swapping out the TH350 for the 4l80E. This is in a 1972 LWB Chevy 4x4. With the new transmission length, I need to make up around 4-1/2 inches. Was thinking of setting the transmission and transfer case mount back around 3 inches and moving the engine forward 1-1/2 inches. I'm sure someone has done this and has a recommended setup. I would like to gain a little bit of firewall room. Thanks __________________ 72 GMC SuperCustom 4x4 1972 Chevrolet Cheyenne Super 4x4

03-23-2021, 08:15 PM	#2
WestButteTruck Kung Fu Master Join Date: Oct 2005 Location: Montana Posts: 543	Re: Longer transmission and moving mounts I thought I would add that the engine is a 400 sbc and I hope to keep the stock radiator, shroud, possibly fan, etc. Probably just need to find out how far forward moving the engine is too far without running into issues? __________________ 72 GMC SuperCustom 4x4 1972 Chevrolet Cheyenne Super 4x4 Last edited by WestButteTruck; 03-23-2021 at 08:16 PM. Reason: spelling

03-24-2021, 11:08 AM	#3
kwmech Senior Member Join Date: Mar 2003 Location: Colfax-California Posts: 8,387	Re: Longer transmission and moving mounts Move the front motor mount cross member forward to the next hole found on the drivers side. You'll have to drill the frame on the right (this is a good time to upgrade to 7/16 bolts) This places the engine in about the 2wd position. So for ease, you'll need a 2wd fan shroud, 2wd upper and lower radiator hoses and a 2wd throttle cable. Underneath at the trans-- drill holes where needed. You'll have to modify the floor pan for the 4wd shifter Forgot also that there will need to be a little fabrication on the automatic linkage to the trans. The pivot will have to be modified moving it closer to the leaf spring shackle. Been a couple years since I did a T400 in a K5 Last edited by kwmech; 03-25-2021 at 01:02 AM.

03-24-2021, 04:16 PM	#4
WestButteTruck Kung Fu Master Join Date: Oct 2005 Location: Montana Posts: 543	Re: Longer transmission and moving mounts Thanks for the info, I appreciate it! __________________ 72 GMC SuperCustom 4x4 1972 Chevrolet Cheyenne Super 4x4

03-25-2021, 11:14 PM	#5
79vette Registered User Join Date: Jan 2017 Location: Sandy, UT Posts: 191	Re: Longer transmission and moving mounts I added a Ranger overdrive in my K5 (like a stick shift version of a Gearvendor that goes in front of the trans). I did not want to deal with moving the engine, checking fan clearance, etc and just moved the transfer case crossmember back ~7" and drilled the frame to match. Left the engine in the original position. This is what the drivetrain looks like from the top. If pics of the relocated crossmember would be useful I can put some up tomorrow. __________________ 1988 "Crane Truck" C30 - 350, SM465, with a 15' knuckle crane - thread 1986 M1009 - 6.2 Diesel, SM465, 2 speed aux trans, NP205 - thread 1979 Corvette - 350 T5 1977 Jimmy - 350, TH400, NP203 1982 Blazer - 350, 700R4, NP208 - Totalled, now a parts truck Scratch built 16' flatbed trailer - thread

03-26-2021, 07:20 AM	#6
Bigdav160 Registered User Join Date: Apr 2011 Location: Klein Texas Posts: 3,852	Re: Longer transmission and moving mounts I did a 700R4 and moved the engine forward. My stock 4x4 fan shroud would not work without cutting. I instead made one out of aluminum. My exhaust also interfered with the motor mount/crossmember and required a little bit of grinding but I am running aftermarket Tru-ram manifolds __________________ My Classics: '72 K20 Suburban + '65 Dodge Town Wagon '72 Corvette Roadster +'67 Corvette Roadster '73 Z-28 Camaro '63 Ford SWB Uni Pickup '50 Ford Coupe

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