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swathdiver

swathdiver

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Made a highway run today with the Yukon XL. 115 miles each way on E85 @ 74% alcohol content. Set the cruise for 73 mph and just over 2000 rpms, 2010-2020 thereabout. Gas mileage going north was 14.8 mpg and going south was 14.7 mpg.

By way of comparison, the truck has made 4 runs (complete tanks of fuel) on E85 at 100% highway driving, average speed above 48.3 mph. The 4 averaged 52.9 mph and delivered 13.7 mpg.

Have another 100 mile run Sunday to finish off that tank of fuel and will report back with the final numbers.

Ambient temperature was 92 degrees and the transmission temperature was 160 degrees during the run while on the highway.

Oil pressure hit a low of 19 psi when stopped at a light. :-(

The purpose of this report is to document the changes in fuel efficiency, if any, between the old 3.42 gears and the new 3.73 gears.
 
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mountie

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Made a highway run today with the Yukon XL. 115 miles each way on E85 @ 74% alcohol content. Set the cruise for 73 mph and just over 2000 rpms, 2010-2020 thereabout. Gas mileage going north was 14.8 mpg and going south was 14.7 mpg.

By way of comparison, the truck has made 4 runs (complete tanks of fuel) on E85 at 100% highway driving, average speed above 48.3 mph. The 4 averaged 52.9 mph and delivered 13.7 mpg.

Have another 100 mile run Sunday to finish off that tank of fuel and will report back with the final numbers.

The purpose of this report is to document the changes in fuel efficiency, if any, between the old 3.42 gears and the new 3.73 gears.
I got gas today ( West Palm Beach )...... $ 2.93 ( No stress on MPG )
 

Marky Dissod

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Made a highway run today with the Yukon XL. 115 miles each way on E85 @ 74% ethanol content. Set the cruise for 73MpH and just over 2000RpM, 2010-2020 thereabout.
Gas mileage going north was 14.8MpG and going south was 14.7MpG.

By way of comparison, the truck has made 4 runs (complete tanks of fuel) on E85 at 100% highway driving, average speed above 48.3MpH.
The 4 averaged 52.9MpH and delivered 13.7MpG.

Have another 100 mile run Sunday to finish off that tank of fuel and will report back with the final numbers.

Ambient temperature was 92F and the ATF temp was 160F during the run while on the highway.

Oil pressure hit a low of 19 psi when stopped at a light. :-(

The purpose of this report is to document the changes in fuel efficiency, if any, between the old 3.42 and the new 3.73.
In a nutshell, though how are 3.73 treating you compared to 3.42 so far?
(Pretty sure the answer strongly implies that more people should be doing it ...)
 
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swathdiver

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In a nutshell, though how are 3.73 treating you compared to 3.42 so far?
(Pretty sure the answer strongly implies that more people should be doing it ...)
They're great! It's an incremental improvement, not huge but is noticeable. Acceleration, 1/4 mile times, horsepower to the ground and towing have all improved a little bit. Around town gas mileage is better and highway seems to be the same or better. Still working on quantifying that.

I recommend 3.73s if someone needs new gears or wants to make a smaller change than 4.10s. Most who put 4.10s in love them. I didn't want to be spinning the motor that much on the highway. Maybe I'm wrong, don't know.

Someday I'll get around to 4.10s or lower on the 2012 Sierra. She's lifted on 35s and came with 3.73s.
 
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swathdiver

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On Sunday morning I refueled with E85 @76% and headed south at 66 mph and she delivered 15.7 mpg. This morning I went north at 70 mph for a while and she delivered 15.1 mpg. When I rang up 77 and 79 mph the mpgs only dropped to 14.9 after 30 minutes.

Then I had a little medical scare and had the kids drop me off at the emergency room while they picked up medicine for my wife who came back with Covid from New York. I'm home now and fine, a little sore and hoping I don't catch her Covid! Poor thing!

Kids used my truck around town so not sure what the average dropped down to, the low fuel light came on though. I'll refuel it tomorrow or the next day and then have data for the stats.
 
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swathdiver

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"Hey Dad, come outside and take a look at this", my daughter said!

20250722_191312.jpg20250722_191316.jpg

So, do you think it might be a road hazard or maybe someone hit it in the parking lot? None of us recall jumping or backing into a curb.

The hunt has begun for a replacement...
 
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swathdiver

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The search took about two weeks. Finally connected with a guy in LaBelle and got them home and switched out the passenger side. Came off a 2008 Yukon XL.

The drive out to LaBelle and back was nice with my bride by my side and we got to have breakfast at our favorite diner in Okeechobee.

2 of the 4 inserts on the old board were broken, the brass threaded insert molded into the board that the bracket bolts to. Not sure if they broke because of my fat butt or from the impact.

2008 Yukon XL Running Boards - Jordan - LaBelle - 1.jpg

20250816_180825.jpg 20250816_180833.jpg

Truck is filthy, she was out on the country roads in 4Hi and 4Lo the other day, giving my city slicker nephew some seat time since he got his shiny new learner's permit.

I did not know that GM offered the 5" nerf bars as an accessory. The brackets between our truck and the pickups have different part numbers, the boards appear to be the same. I saw plenty of those for sale and considered them but could not determine whether they would fit or not. It's too hot for me to swap boards from my Sierra to the Yukon and back right now. As it was, I had to have my helper come over for dinner and swap the old one out.

The Yukon has been calculating the alcohol content between 73-76% for the past few months. The Sierra, with her original sensors, has been calculating the alcohol content at 80%. Coincidentally, the trucks have been refueling the same day at the same station and often from the same pump. I reckon this is close enough for TV, what say you?
 
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swathdiver

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Wife and Granny went out to the country butcher to pick up our supply of beef and chicken and when she got back into the truck the shifter did nothing.

Sent a helper over who put the cable back on the lever on the side of the transmission and she was able to back out and drive home. A few minutes later, one of the Dorman 14092s was softened up in hot water and then snapped into the hole and the truck was shifting fine again.

Well, we got lucky, had checked it a few months ago and all was well. A piece of it had broken off. It lasted 5,825 days and 216,367 miles!

This fellow explains it better than I:

 

PG01

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Wife and Granny went out to the country butcher to pick up our supply of beef and chicken and when she got back into the truck the shifter did nothing.

Sent a helper over who put the cable back on the lever on the side of the transmission and she was able to back out and drive home. A few minutes later, one of the Dorman 14092s was softened up in hot water and then snapped into the hole and the truck was shifting fine again.

Well, we got lucky, had checked it a few months ago and all was well. A piece of it had broken off. It lasted 5,825 days and 216,367 miles!

This fellow explains it better than I:

Its that Flarida heat!!! ;)
 

mountie

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Wife and Granny went out to the country butcher to pick up our supply of beef and chicken and when she got back into the truck the shifter did nothing.

Sent a helper over who put the cable back on the lever on the side of the transmission and she was able to back out and drive home. A few minutes later, one of the Dorman 14092s was softened up in hot water and then snapped into the hole and the truck was shifting fine again.

Well, we got lucky, had checked it a few months ago and all was well. A piece of it had broken off. It lasted 5,825 days and 216,367 miles!

This fellow explains it better than I:


Interesting….. check out this “ more secure “ version attachment….
 

mikez71

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Well, we got lucky, had checked it a few months ago and all was well. A piece of it had broken off. It lasted 5,825 days and 216,367 miles!
Mine popped off at 221,401 miles.

I didn't need hot water to get the 14092 bushing installed on mine. My bushing end wasn't ovaled out or anything.
Bushings felt pliable in hand, perhaps my ambient temps were higher idk.
Mine looked just like your video. Now to see how long this dorman can last..

Mountie's first video showed a failed dorman apparently, but looking at that shifter pin (1:40), it could be worn.
Maybe grease obscuring the pin, but if it's worn out, that could explain why some people had bad luck with the dorman bushing.
Also, his bushing looks deformed, as he said "swollen". Might be something to look for on the dorman as a sign it's starting to go..
Screenshot 2025-08-23 090824.png
 
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swathdiver

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Mine popped off at 221,401 miles.

I didn't need hot water to get the 14092 bushing installed on mine. My bushing end wasn't ovaled out or anything.
Bushings felt pliable in hand, perhaps my ambient temps were higher idk.
Mine looked just like your video. Now to see how long this dorman can last..

Mountie's first video showed a failed dorman apparently, but looking at that shifter pin (1:40), it could be worn.
Maybe grease obscuring the pin, but if it's worn out, that could explain why some people had bad luck with the dorman bushing.
(And why we maybe looking for another alternative after awhile)

I threw it in some hot water based on the video watched. Can't say if it was necessary or not.

If mine fails and it's because the lever on the side of the transmission is bad, I'll just replace it and the 2 cables. Zero-timed, it ought to be good for another 16 years.
 
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swathdiver

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Mine popped off at 221,401 miles.

I didn't need hot water to get the 14092 bushing installed on mine. My bushing end wasn't ovaled out or anything.
Bushings felt pliable in hand, perhaps my ambient temps were higher idk.
Mine looked just like your video. Now to see how long this dorman can last..

Mountie's first video showed a failed dorman apparently, but looking at that shifter pin (1:40), it could be worn.
Maybe grease obscuring the pin, but if it's worn out, that could explain why some people had bad luck with the dorman bushing.
Also, his bushing looks deformed, as he said "swollen". Might be something to look for on the dorman as a sign it's starting to go..
View attachment 465783
If that's yours, you might want to replace the lever!
 
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swathdiver

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Was decelerating as the truck approached a light and all of a sudden there was a shudder followed by the CEL and other lights coming and the truck dropped into 1st gear only. Pulled into a parking lot, backed in and turned the truck on and off to see if the transmission would go back to normal, nope. Pulled over and cleared the codes and all was well.

P0700 and U0073 came up on the Torque Pro app.

I figured the problem is either a wiring/connector issue or the TECHM has a problem on its board.

Two guys on here had the same codes, one fixed some chafed wires and the other replaced his TECHM.

Drove it today for a short run to the Pharmacy and back, no issues.

I'm thinking of hooking the MDI and laptop up to the truck and use ACDelco's Data Bus Diagnostic Tool. Have some reading up to do on it, not sure if it will work without codes or not.
 

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Interesting….. check out this “ more secure “ version attachment….
I like the overall concept and have done similar on other vehicles, but a better implementation would be to use a shouldered bolt that threads in from outboard into a tapped hole, with a thin locknut on the backside. Note that he does say he used a shouldered bolt, but that's erroneous -- he used a bolt with a partially-unthreaded shank.

The reason to use a shouldered bolt is the same reason they're used on lawnmower wheels and other things that need to have a tight shaft that doesn't clamp down on the item that needs to rotate. The shoulder of the bolt tightens onto the surface with the threads (or tightens with a bolt on the back side). As he's done it, the bolt will wear the hole in the shift arm.

 

mountie

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I like the overall concept and have done similar on other vehicles, but a better implementation would be to use a shouldered bolt that threads in from outboard into a tapped hole, with a thin locknut on the backside. Note that he does say he used a shouldered bolt, but that's erroneous -- he used a bolt with a partially-unthreaded shank.

The reason to use a shouldered bolt is the same reason they're used on lawnmower wheels and other things that need to have a tight shaft that doesn't clamp down on the item that needs to rotate. The shoulder of the bolt tightens onto the surface with the threads (or tightens with a bolt on the back side). As he's done it, the bolt will wear the hole in the shift arm.

You nailed it…...
We had a Porsche 911 racing at the 12 Hours of Sebring…….. The left/ rear suspension hime joint snapped off…..
Exactly due, to that reason.
 

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