Redrilling Frame for 4L80e - The 1947 - Present Chevrolet & GMC Truck Message Board Network

SabbathFanatic · 11-30-2017, 04:46 PM

I'm putting an LQ4/4L80e into my '71 C10 that had a 305/TH350 in it. I'm planning on using the stock crossmember relocated, and it seems like everyone says to just slide it to where you need it and redrill the holes. Sounds easy enough for the bottom holes, but how do you drill the holes in the topside of the frame?? That doesn't look like there's any way to do it unless I take the cab off. I already have the front clip and bed off, so taking the cab off isn't a huge deal, but I'd rather not have to deal with lining it back up if I don't have to.

geezer#99 · 11-30-2017, 08:49 PM

If you're talking about the stock crossmember that the bellhousing bolts too then you don't need to worry about those top holes. THe reason for that is that your tranny won't fit with that crossmember in place. The crossmember needs to be removed.
Now if you're talking about a crossmember at the tail shaft of your tranny, then it's not stock and depending on design or origin just the bottom holes will work.
So which do you have? Stock (bellhousing) or custom(rear of tranny).

SabbathFanatic · 11-30-2017, 09:10 PM

It's the tail shaft crossmember, but it came stock with the TH350. Stamped steel, not fabricated, and just as rusty as the frame. I don't think I've ever seen one of the bellhousing crossmembers, unless I'm not understanding you correctly...

**PGSigns** · 11-30-2017, 09:24 PM

Your truck is factory auto so it does not have the bell housing crossmember. What I do to drill the holes in the top is use an angle drill and short bits. I use a drill bushing and a 1/8" bit for the first hole and then follow it with a 3/8" right through.
Jimmy

SabbathFanatic · 11-30-2017, 09:49 PM

Yeah, right angle drill sounds like a good plan. Thanks

**Captainfab** · 12-01-2017, 01:14 AM

You can also buy longer that normal drill bits that will reach the top flange when passing thru the holes in the bottom flange.

71cheyennesuperlongb · 12-01-2017, 01:25 AM

Years ago I installed a 700r in my longbed I took a 6inch piece of 3/8 stainless tubing and tig welded it to a 3/8 drill bit to reach through the frame.

SabbathFanatic · 12-01-2017, 01:53 AM

Quote:

Originally Posted by Captainfab

You can also buy longer that normal drill bits that will reach the top flange when passing thru the holes in the bottom flange.

This seems kind of obvious now that you said it...

11-30-2017, 04:46 PM	#1
SabbathFanatic Registered User Join Date: Nov 2017 Location: Denver, CO Posts: 33	Redrilling Frame for 4L80e I'm putting an LQ4/4L80e into my '71 C10 that had a 305/TH350 in it. I'm planning on using the stock crossmember relocated, and it seems like everyone says to just slide it to where you need it and redrill the holes. Sounds easy enough for the bottom holes, but how do you drill the holes in the topside of the frame?? That doesn't look like there's any way to do it unless I take the cab off. I already have the front clip and bed off, so taking the cab off isn't a huge deal, but I'd rather not have to deal with lining it back up if I don't have to. __________________ 1971 C10 - LQ4/4L80E swap in progress 1988 K3500 - 8.1 swap planned

11-30-2017, 08:49 PM	#2
geezer#99 Registered User Join Date: Aug 2009 Location: Bowser Posts: 13,516	Re: Redrilling Frame for 4L80e If you're talking about the stock crossmember that the bellhousing bolts too then you don't need to worry about those top holes. THe reason for that is that your tranny won't fit with that crossmember in place. The crossmember needs to be removed. Now if you're talking about a crossmember at the tail shaft of your tranny, then it's not stock and depending on design or origin just the bottom holes will work. So which do you have? Stock (bellhousing) or custom(rear of tranny).

11-30-2017, 09:10 PM	#3
SabbathFanatic Registered User Join Date: Nov 2017 Location: Denver, CO Posts: 33	Re: Redrilling Frame for 4L80e It's the tail shaft crossmember, but it came stock with the TH350. Stamped steel, not fabricated, and just as rusty as the frame. I don't think I've ever seen one of the bellhousing crossmembers, unless I'm not understanding you correctly... __________________ 1971 C10 - LQ4/4L80E swap in progress 1988 K3500 - 8.1 swap planned

11-30-2017, 09:24 PM	#4
PGSigns Senior Member Join Date: Jan 2011 Location: Hayes Va Posts: 4,569	Re: Redrilling Frame for 4L80e Your truck is factory auto so it does not have the bell housing crossmember. What I do to drill the holes in the top is use an angle drill and short bits. I use a drill bushing and a 1/8" bit for the first hole and then follow it with a 3/8" right through. Jimmy __________________ 60 to 66 Chevy and GMC window decals http://67-72chevytrucks.com/vboard/s...d.php?t=661131 Good friends, good food and a hotrod what else do you need? 1966 BBW long fleet Daily driver 1965 BBW short fleet Sold and going to a good home 1965 Suburban 2003 3500 Duramax 2005 Ultra Classic

11-30-2017, 09:49 PM	#5
SabbathFanatic Registered User Join Date: Nov 2017 Location: Denver, CO Posts: 33	Re: Redrilling Frame for 4L80e Yeah, right angle drill sounds like a good plan. Thanks __________________ 1971 C10 - LQ4/4L80E swap in progress 1988 K3500 - 8.1 swap planned

12-01-2017, 01:14 AM	#6
Captainfab 60-66 Nut Join Date: Mar 2007 Location: Coeur d'Alene, Idaho Posts: 23,246	Re: Redrilling Frame for 4L80e You can also buy longer that normal drill bits that will reach the top flange when passing thru the holes in the bottom flange. __________________ Power Steering Box Adapter Plates For Sale HERE Power Brake Booster Adapter Brackets For Sale '63-'66 HERE and '67-'72 HERE and '60-'62 HERE and "60-'62 with clutch HERE Rear Disc Brake Brackets For Sale. Impala SS calipers HERE Camaro Calipers HERE D52 Calipers HERE 6 Lug HERE Hydroboost Mounting Plates HERE

12-01-2017, 01:25 AM	#7
71cheyennesuperlongb Registered User Join Date: Aug 2015 Location: Alcoa;Tn Posts: 208	Re: Redrilling Frame for 4L80e Years ago I installed a 700r in my longbed I took a 6inch piece of 3/8 stainless tubing and tig welded it to a 3/8 drill bit to reach through the frame. __________________ '71 Cheyenne Super LWB - Second Owner in 39 Years! '70 CST/10 SWB - Soon to be Daughter's truck when finished



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