Question on RPMs
Gone, but not forgotten
Joined: Oct 2005
Posts: 5,026
Likes: 2
From: Charlotte-Fairbanks-Bflo
Generally speaking you're correct Jim, but if the truck was custom ordered, highly unlikely nowadays, it could have 4.10's
Post Fiend
Joined: Mar 2007
Posts: 26,966
Likes: 50
From: Texas
S409H is the plant code where the axle was built
L73 means you have a Limited slip 3.73
10 5 means it's the standard Ford 10.5" ring gear diameter
1B28 is the date code (year month day) the axle was made.
Let us know how the jack test turns out. As Mark mentioned, use a piece of chalk to mark the bottom of the tire and the driveshaft so you can count turns. Don't forget to chock the front tires and use a good set of jack stands.
Laughing Gas
Joined: Mar 2004
Posts: 789
Likes: 16
From: West Coast/L.A. Area
Shouldn't there be a "3" in front of the "L73" Chris?
Also on the driver door tag for "axel", a 4:10 would be "F2". Don't know what a 3:73 would be.
Also on the driver door tag for "axel", a 4:10 would be "F2". Don't know what a 3:73 would be.
Post Fiend
Joined: Mar 2007
Posts: 26,966
Likes: 50
From: Texas
Hotshot
Joined: Jul 2003
Posts: 12,177
Likes: 40
From: Newport, WA
I'm running 285's on stock wheels with 3.73's and with my cruise set at 65 indicated (which is roughly 68-69 mph) I turn just under 2000 RPM's on the tach. I've got an auto trans and 4x4 as well (trying to give dannyboy as much info as possible for comparisons).
Go Bills !
Joined: Jan 2008
Posts: 2,778
Likes: 65
From: Buffalo, NY
265 / 75 /16 tires. Almost time to get new. Might make it one more summer.
Onway home today. Cruise Control set to 70mph (just for this test) usually i don't go over 65.
2050-2100 rpm. 3:73 gear
Onway home today. Cruise Control set to 70mph (just for this test) usually i don't go over 65.
2050-2100 rpm. 3:73 gear
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Post Fiend
Joined: Feb 2007
Posts: 14,541
Likes: 2
From: Dallas-Ft. Worth
Yes, there should be a "3" in front of the "L". "3L73" is 3.73 LS, "3 73" is an open 3.73 diff. His tag may just be in bad shape and he couldn't see the leading 3. Door sticker axle code for 3.73 LS is C1. Here's the site I go to for diff questions:
Automotive What is my Ford rear end ratio, do I have positraction
Automotive What is my Ford rear end ratio, do I have positraction
Post Fiend
Joined: Mar 2007
Posts: 26,966
Likes: 50
From: Texas
No need to copy all my info Gary. The basic stuff is available in the workshop manual. In case you missed the earlier thread https://www.ford-trucks.com/forums/7...ml#post6145140
you might want to bookmark that so you have access to all the goodies available there.
Joe. Good to see you hanging around. How are things over there?
you might want to bookmark that so you have access to all the goodies available there.
Joe. Good to see you hanging around. How are things over there?
Laughing Gas
Joined: Mar 2004
Posts: 789
Likes: 16
From: West Coast/L.A. Area
OMG - that is a resource. Chris. I hate to go off thread but I got to know: I hired a grandson of one of my good friends who was a mechanic by trade to help rebuild my '91 F350 460 engine. We didn't know it at the time but he was on drugs. He showed up less and less and finally disappeared altogether, but the engine was completed. Me and his grandfather put the engine back in the truck and it had a ticking sound which we thought was the adjustable roller lifters. It wasn't - it was that he forgot to put the cam retainer back. Cam slipped, threw metal everywhere and pretty much ruined the engine. I can't afford to do much now except to try to clean up and put back what I have. Oo you know if there a workshop manual available for that engine on line?
Post Fiend
Joined: Mar 2007
Posts: 26,966
Likes: 50
From: Texas
Sorry Gary, but I don't know of one. I was just lucky enough to stumble across the super duty ones that only go back to 96. I think the 91 will probably be a paper manual. You could check ebay, or for a real copy go to helminc dot com.
Thread Starter
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Junior User
Joined: Jan 2008
Posts: 60
Likes: 0
From: Chehalis, WA
Hey Everyone,
I did a manual test last weekend and I do indeed have the 3.73 gears just like the tag and door sticker say.
Any ideas why my MPH is so low at 2000 RPMs? Everything is running just fine (as far as i know with my limited knowledge of diesels).
Thanks
I did a manual test last weekend and I do indeed have the 3.73 gears just like the tag and door sticker say.
Any ideas why my MPH is so low at 2000 RPMs? Everything is running just fine (as far as i know with my limited knowledge of diesels).
Thanks