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Gear axle ratio

Joseph Novak Jr

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My codes for the gear ratio on my 1992 GMC 2500 suburban are worn off in glove box...I need to order new oil cooler lines...but for some reason, the hoses are ratio specific...
I can't order my leaking hoses until I know the gear ratio...is there something I could look at on the gear pumpkin housing?
Any help appreciated
 

THEFERMANATOR

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Will L.

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Sorry Joeseph, my mistake. I live with 6.2/ 6.5 diesel on the brain. Thefermenator is correct as usual.
 

Joseph Novak Jr

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Sorry Joeseph, my mistake. I live with 6.2/ 6.5 diesel on the brain. Thefermenator is correct as usual.
That's ok...Rock Auto has the lines...but asking my gear ratio...I honesty you do not understand why that would matter? For just having oral line Cooling what's that have to do with gear ratio show? Maybe I should just go with the 4:10. to 4:56 gear ratio be done with it I'm guessing they're heavier-duty? I have no idea why they make different hoses for different gear ratios
 

Will L.

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You can just jack up the rear axle rotate - make crayon or soapstone mark at bottom of tire and bottom of driveshaft. Turn tire 1 turn 1 revolution and count the driveshaft revolutions. That is your ratio.
 

Joseph Novak Jr

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1/2 of my question...does anyone have an answer as to why the gear ratio matters for the oil cooling lines? I'm kind of confused on that one...I work with some hydraulics...you would think the lines would just be rated for a certain pressure...a Maximum PSI ?
Thanks again
 

JayTheCPA

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Chances are good that the ratio is either 3.73 or 4.10.

Tree easy ways I can think of to get the ratio as the truck was built:
- Dealership (probably free)
- Compnine <dot> com (not free, nominal charge)
- If you happen to remember the RPM's at any given highway speed, we can make an educated guess (free, but you get what you pay for ;) ) This will also require posting whether the tires sizes are OE or something else.

Naturally, if somebody changed the ratio, then it will not match GM's RPO per their records.
 

Joseph Novak Jr

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Chances are good that the ratio is either 3.73 or 4.10.

Tree easy ways I can think of to get the ratio as the truck was built:
- Dealership (probably free)
- Compnine <dot> com (not free, nominal charge)
- If you happen to remember the RPM's at any given highway speed, we can make an educated guess (free, but you get what you pay for ;) ) This will also require posting whether the tires sizes are OE or something else.

Naturally, if somebody changed the ratio, then it will not match GM's RPO per their records.
That is another helpful reply, thanks to everyone who have input...I will get back to you on the highway speed and rpm ...it does still have stock tires and wheels, but you never know what someone may have changed over the years like you mentioned...I just bought tbisSuburban last Thursday, so I'm just trying to fix it to drive without leaving a oil trail
 

Will L.

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STOP!!! TIME OUT!!!

If the oil cooler lines are leaking DO NOT DRIVE IT! A small leak in oil cooler lines blows into dumping all engine oil in a couple seconds then a toasted engine. Seen it too many times.

Call or go to a dealership with the vin number. Get the part number from them even if they can not sell the part any more. If part fitment was determined by original rpo of gearing somehow, it doesn't matter if someone swapped in a ford 9". The original componet number is all that is needed for aftermarket. I never once when working in dealership had to go look at rpo codes for the parts department.
 

Joseph Novak Jr

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Chances are good that the ratio is either 3.73 or 4.10.

Tree easy ways I can think of to get the ratio as the truck was built:
- Dealership (probably free)
- Compnine <dot> com (not free, nominal charge)
- If you happen to remember the RPM's at any given highway speed, we can make an educated guess (free, but you get what you pay for ;) ) This will also require posting whether the tires sizes are OE or something else.

Naturally, if somebody changed the ratio, then it will not match GM's RPO per their records.
Roughly 2100,2200 RPM @ 60 MPH
 

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Many times the gear ratio could effect which radiator it got. Lower geared trucks normally got the big radiator for towing while taller gears meant hwy duty and the smaller radiator. The oil cooler is part of the radiator, so you had to know which radiator to order lines.
 

Joseph Novak Jr

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Many times the gear ratio could effect which radiator it got. Lower geared trucks normally got the big radiator for towing while taller gears meant hwy duty and the smaller radiator. The oil cooler is part of the radiator, so you had to know which radiator to order lines.
Well, I guess we will see when the lines arrive ...I myself am going with a tow vehicle with at least the 4:10 gears...as long as they threatened and they no longer LEAK .. I will be happy... I won't be driving this vehicle long distances let alone towing anything heavier than a 55 Chevy
 

Joseph Novak Jr

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Well, I guess we will see when the lines arrive ...I myself am going with a tow vehicle with at least the 4:10 gears...as long as they threatened and they no longer LEAK .. I will be happy... I won't be driving this vehicle long distances let alone towing anything heavier than a 55 Chevy
As long as they "thread" in... I am done using talk to text! I'm sorry guys I've spoken into this phone many times and it did not say what I said!
 

WarWagon

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Many times the gear ratio could effect which radiator it got. Lower geared trucks normally got the big radiator for towing while taller gears meant hwy duty and the smaller radiator. The oil cooler is part of the radiator, so you had to know which radiator to order lines.

Exactly this. GM also offered HD cooling systems as an option on some engines that made no sense. HD cooling system on a 1993 TBI 160HP V6 was a joke. However one difference for the said example the fan size and blade pitch made short work of 'light duty' fan clutches and burned them out. So keep in mind any cooling system parts can be different: if the fan clutch size looks different it's the wrong part even though it bolts up.

As you are cooking oil cooler lines (age alone maybe) remove the oil cooler, if equipped, and clean the airflow clogging debris out that collects behind the oil cooler on the condenser. You would have up to 3 oil cooler lines if it uses both a radiator and air to oil cooler.
 

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The oil cooler doesn't come out unless it's an aftermarket add on. The oem oil coolers for 5.7l 4x4 trucks was in the drivers side radiator tank. Light duty 4x4 pickups even with a 5.7l didn't get the oil cooler. It was an option on 5.0l and 4.3l trucksto get the oil cooler on 4x4's. I don't recall seeing a 2 wheel drive with a oil cooler. Many have went to the junkyard and gotten one of the 4x4 oil filter adapters without the oil cooler lines, and just deleted the oil cooler.
 
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