3.73-4.11 and up.
How do axle ratios affect engine longevity?
- Thread starter 2000Trooper
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It was Cadillac owners that complained about getting an Olds or Chevy engine in their Cadillac. Never mind that the Olds and Chevy were world's more reliable than the HT series of engine that Cadillac had at the time.
@bullwinkle - my 10r80 was super clumsy and then started missing shifts, and on 2 occasions gave up, dropped to neutral and wouldnt work until restarted. Dealer reflashed, I tried a fluid change or 2 to no avail.
added about 1/5 a bottle of lubeguard red to mine (2-2.5 oz or so, a very small dose) and it is now as elegant as the unit in our Lexus. It absolutely transformed that transmission.
I used a measured mityvac, pulled out fluid myself, measured the fluid removed, and then ran a funnel and long hose down from the hood and dribbled the same amount back in. Except: fun fact. I’m not sure how picky thes units are about getting the exact fill level. the oem level had a dry dipstick. So I ended up putting more in, a quart or two.
im pretty sure @ctechbob might have a method he likes also. Bob?
im pretty sure @ctechbob might have a method he likes also. Bob?
I just have a tool I made up that attaches to a 12v pump to suck the fluid out and spray it all over the side of the truck and Acura....ok, that only happened once and I fixed the issue to not happen again. (The discharge tube came flying out of the container I was using and whipped around like a firehose.....oops)
There is an 'official' 10R80 tool to hook to a pump to suck the fluid out, but near as I can tell, it is a bent piece of pipe, that they ask $100+ for. Although they do call it a 'transmission fill' tool, I'm pretty sure its intended use is to suck the fluid out.
I took a metal toilet standpipe, filled it with sand (to prevent kinking) heated and bent it into a shepherds crook looking shape. Attach it to the pump and suck out the fluid. I usually get about 4 qts out. Refill, check level, and roll with it. (I also use 1oz per qt of LG Platinum)
I'm doing the aluminum PPE pan sometime this year, for the express purpose of having a drain plug. I don't really care that it adds cooling, I've never seen my temps climb, even towing heavy.
I have found evidence online that Ford did have a somewhat automatic fill tool. I thought it was a really cool idea, but I've only seen one for sale and it was in the UK, Ford US doesn't seem to have any idea it existed.
Video of it in action.
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I have re-geared my Wrangler twice (not counting the original gears), from 4.10 (33" & 35" tires) to 4.88 (35" & 37" tires) to 5.13 (37" tires).
I believe under-geared engines would wear faster than over-geared simply because an under-geared engines and subsequently transmissions are working harder and lugging/constantly up and down shifting.
I believe under-geared engines would wear faster than over-geared simply because an under-geared engines and subsequently transmissions are working harder and lugging/constantly up and down shifting.
My s2000 cruises at 4krpm+ on the highway and they routinely last 200k miles +
Yep, my Miata was the same way. If you were doing 80 on the interstate you were at 4-4500, and it was happy there. I took several fairly long interstate trips in it. Of course, that BP was built to take that sort of thing and was a pretty overbuilt little lump.
I think it all depends. In my trucks case with 3.42 gears I'm usually driving in 3rd gear at 2100 RPM about 55mph or on the highway at around 2700rpm. If I put it in 4th it will have to unlock the torque converter on every little grade (fully loaded half ton 4wd with a 4.8). If I had 3.73 gears I'd be able to use overdrive more often.
If I left it in overdrive all the time and just let it shift frequently it does about 1400 rpm at 55mph which is borderline lugging it. So I feel like it's running the engine more efficiently at around 2000rpm or more.
Is lugging or revving worse, the debate will never end. I personally hate factory gears most times. They are for MPG/EPA tests and that's it. Usually a truck/suv is much nicer to drive after a gear change.
I have wondered about this too, but unfortunately I came to the conclusion that there is no simple answer because there are way too many other variables involved- how the vehicle is used, the design of the engine and its inherent weaknesses, which specific engine part we are discussing, etc.
A lightly loaded vehicle with an adequately powered engine constantly driven at high ish speeds on perfectly flat roads may see the best overall engine longevity with the taller gearing since the load on the engine should be pretty low anyways.
A vehicle loaded more heavily and/or driven at the same speeds on hilly roads will likely experience less overall engine wear with the shorter gearing since it won't be loaded as heavily while climbing and will have more oil and coolant flow relative to the work it's doing.
An engine known for wearing out its valvetrain first MIGHT last longer with the taller gearing since the valvetrain isn't directly affected by the engine's load, but rather RPM. There's no guarantee this would be the case though, other less obvious things like oil splash, the inertial forces on the valves, etc can have less obvious effects.
On the other hand, an engine known for wearing the bottom end bearings prematurely would likely benefit from the shorter gearing to keep the load down since higher load seems to wear the bearings more than higher RPM assuming the engine isn't over revved.
The engine is going to be generating the same amount of horsepower and doing the same amount of work either way. Whether generating more torque or spinning at a higher RPM would cause more wear will certainly be specific to that engine design and its usage conditions.
A lightly loaded vehicle with an adequately powered engine constantly driven at high ish speeds on perfectly flat roads may see the best overall engine longevity with the taller gearing since the load on the engine should be pretty low anyways.
A vehicle loaded more heavily and/or driven at the same speeds on hilly roads will likely experience less overall engine wear with the shorter gearing since it won't be loaded as heavily while climbing and will have more oil and coolant flow relative to the work it's doing.
An engine known for wearing out its valvetrain first MIGHT last longer with the taller gearing since the valvetrain isn't directly affected by the engine's load, but rather RPM. There's no guarantee this would be the case though, other less obvious things like oil splash, the inertial forces on the valves, etc can have less obvious effects.
On the other hand, an engine known for wearing the bottom end bearings prematurely would likely benefit from the shorter gearing to keep the load down since higher load seems to wear the bearings more than higher RPM assuming the engine isn't over revved.
The engine is going to be generating the same amount of horsepower and doing the same amount of work either way. Whether generating more torque or spinning at a higher RPM would cause more wear will certainly be specific to that engine design and its usage conditions.
I would say with very few exceptions a road going automotive engine would last longer being asked to make 100 HP at 3000 rpm when compared to the same engine being asked to make 100 hp at 2000 RPM.
More RPM means better lubrication in most circumstances, less engine load at a higher rpm means less piston ring pressure on the cylinder. More rpm mean better hydrodyamic film strength for all the bearings, etc.
More RPM means better lubrication in most circumstances, less engine load at a higher rpm means less piston ring pressure on the cylinder. More rpm mean better hydrodyamic film strength for all the bearings, etc.
In 1978 (!) my dad ordered a g30 Chevy van with what was supposed to be the tallest rear end (2.73?). What got delivered was the shortest. He didn’t complain and took delivery.
By the time I inherited it in high school in the early 90s, that low top speed and screaming 350 probably kept me alive. It was so slow and loud I dared not Ever go over 65 mph.
it ran perfectly even though I never changed the oil and the body rotted so badly you could push the rear doors to the left and right.
By the time I inherited it in high school in the early 90s, that low top speed and screaming 350 probably kept me alive. It was so slow and loud I dared not Ever go over 65 mph.
it ran perfectly even though I never changed the oil and the body rotted so badly you could push the rear doors to the left and right.
HT4100 was their first try at making a complicated unreliable engine. It was perfected with the Northstar
What is the tire size diameter? That directly affects overall gear ratio. 3.42 gears in my Silverado with 33" tires is about the same as 2.56 in my Cutlass with 235/60r15.
Except the darn head gaskets. Left my wife & I 1500 miles away from home. Loved the 98 Eldorado ETC. This was before they allowed lower than Premium Fuel.
HT4100 was their first try at making a complicated unreliable engine.
I meant they perfected unreliability and overcomplexity. They are terrible engines. There is a reason a mint Caddy with low miles is $3k.
I believe in thermodynamic and ICE engineering terms, if you compared two identical engines/setups, under the same exact conditions, the one that spins more RPMs and burns more fuel over a given time/miles is going to have more wear.
You could never measure this from one vehicle to the next in the real world.
You could never measure this from one vehicle to the next in the real world.
