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Quadrasteer 8.1L Suburban tow rig

2003 Suburban 2500 Quadrasteer camper towing 8.1L 6.0L swap 4L80-E
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Pretty sure it's always been there and I just didn't notice till I took the pan off. The missing piece isn't inside, not on my floor, not in my trailer.

Interesting that the casting crosses to 2 different part numbers. I found a pan locally, but it seems to be the version without the oil level sensor hole. So I could drill and tap or delete the sensor and just check it a lot. Now I do check it a lot while towing, but hardly ever on a DD.

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It's clear I'm way out of SBC land here, with used pans for $250 on eBay and new ones hardly available. Almost nothing in the aftermarket. Hot Rod swaps are custom altering stock pans for clearance.
 
This is the pan from my donor 8.1L engine from a 2002 Silverado.
 
Guys on the 8.1L facebook group are saying to have it welded up. This would seem more plausible if I had the missing piece. Not sure what the metallurgy is to get a patch. Part numbers 12560248 and 12559764 are discontinued and superseded by 12574833, which is also discontinued. There is an aftermarket pan Spectra GMP75A, which is available, so this may be the direction to go. I also found a 12559764 (no oil sensor hole) about an hour's drive from me. Nobody lists the Spectra pan as fitting Suburban, but it is listed for Avalanche and Yukon XL. Possibly the Suburban didn't get the oil level sensor, but you would think they could just supply a plug?

For my application, I want it the same as the 6.0L in place. So if the harness is there for the oil level sensor I want one, which should mean a drill and tap purchase.

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RockAuto also lists a PIONEER 501505, but I think that's actually the small block pan. Always a give-away when they list every truck, including Escalade.
 
I tried ordering Spectra GMP75A from a couple places, but they were sold out after ordering. Finally sourced an OEM pan on eBay. Key was to search on the interchange number - 311-00893.

So waiting on a few parts in the mail, I crossed the broken AC bracket off my list, using a scrap of 1/4" and a short steel spacer.

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Yeah, the back side turned out pretty ugly. I kept building weld up to tie the spacer, new piece and bracket together. I don't know if this is a common failure to know if the rework needs to be stronger or if this tensioner ear was just another victim of careless engine pulling.

(I won't be using this compressor, it's just for mock-up).
 
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76zimmer said:
Luke get in touch w @gregducato about convertors.
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Greg says to get GM88, which is 1600-1800 stall, as opposed to what I have now, which must be GM88H, 2200-2400 stall. That's probably the one thing I don't like about the Suburban is the loose converter. Just makes nudging a trailer or getting into the barn harder. I suspect they pair 6.0L/4L80-E with loose converters to make up for the relatively tall 1st gear of 4L80, plus the high torque peak of LQ4. But isn't that why we run lower differential gears?

Anyway, with serious low end torque, why make it rev over 2000 before the vehicle moves?
 
I was backing a loaded trailer over curbs today at idle!
 
1st problem is that this radiator doesn't fit. The 2" plastic radiator spacer came out as advertised, but this rad does not drop into the holes underneath. It almost fits by putting the PS peg in the existing hole, just like the small block rad, but that makes it hit the battery tray on the DS and the DS peg hits the body mount.

This picture is to show that there is only one position this (so-called) Suburban rad will fit in, but it will require 2 new holes in the bottom support and 2 new nuts up top. Sellers show that they have one to fit, but $400+ and I can't find any information on mounting points. Haven't made up my mind yet. Need to verify how the shroud openings line up.

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If I used the old rad, the tranny cooler lines would fit, but I'd have to make custom oil cooler lines. I did have some temp problems towing with the 6.0 stock, but it all went away with a new fan clutch. I haven't verified that the 6.0 water pump is centered exactly like the 8.1, but the clutches and fans have the same mounting features.

Seems logical to run bigger rad with bigger engine. Goal is to be like it was all factory. I'm not held up by this for now, anyway.
 
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