Using a gear too tall
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From: redding U.S.A.
Using a gear too tall
When i'm at a stop sign on a flat road, or rolling slightly downhill, i usually start off in second. I have a m5od and 3.55 gears with 31"s. Whats that clattering noise i hear from the engine? is that piston slap?
Should i stop doing this to my baby?
First gear is great to get the truck rolling... but 25mph at 4000rpm? thats a bit too grunty for drivin down the road with an empty bed.
The only good thing about first gear is that its unstopable, and it seams like i can take a porsche off the line with it.
Should i stop doing this to my baby?
First gear is great to get the truck rolling... but 25mph at 4000rpm? thats a bit too grunty for drivin down the road with an empty bed.
The only good thing about first gear is that its unstopable, and it seams like i can take a porsche off the line with it.
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Joined: Mar 2003
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From: Colorado
Using a gear too tall
I get MAYBE 10-15 mph in 1st at 3,000 rpm. T-18 granny. I can take almost ANYTHING for the first 25-50 feet in first gear. Now THAT'S a HOLE SHOT! Then I have to wait for the r's to drop before I can grab second. I almost always start out in 2nd - including MOST hills.
'not sure about the clatter...could be a few things
'not sure about the clatter...could be a few things
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From: redding U.S.A.
Using a gear too tall
well it isn't really clatter.. Sounds nothing like valve train clatter...
Arg, hard to describe engine noises....
When i'm in a gear too tall, as i often am, its sort of a low grumbly noise... sounds just like the engine is stressed or not quite burning all the fuel, but i just wanted to check with you guys since i'm a paranoid kid and cower in the face of your superiour experience and mechanical knowledge.
I don't have a granny gear... I wish i had 1.5 gear. First is just a tiny bit too tall to be able to easily skip it.
I wonder how much torque is going to the wheels in first gear... and how bout first gear 4 wheel low... or... reverse 4 wheel low.... monsterous!
Arg, hard to describe engine noises....
When i'm in a gear too tall, as i often am, its sort of a low grumbly noise... sounds just like the engine is stressed or not quite burning all the fuel, but i just wanted to check with you guys since i'm a paranoid kid and cower in the face of your superiour experience and mechanical knowledge.
I don't have a granny gear... I wish i had 1.5 gear. First is just a tiny bit too tall to be able to easily skip it.
I wonder how much torque is going to the wheels in first gear... and how bout first gear 4 wheel low... or... reverse 4 wheel low.... monsterous!
Freshman User
Joined: Sep 2002
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From: Guelph Canada
Using a gear too tall
I know the sound your talking about. Not 100% sure what the source is....... 
Almost sounds like something is running unbalanced at that speed or something. 
Yep noises are hard to explain.
I'm pretty sure I remember reading something about it in the owners manual though. manual says ignore it.
Drive on!
Almost sounds like something is running unbalanced at that speed or something. Yep noises are hard to explain.
I'm pretty sure I remember reading something about it in the owners manual though. manual says ignore it.
Drive on!
Post Fiend
Joined: Jan 2000
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From: Metro Detroit (Redford)
Using a gear too tall
My first guess is that the rattle is the engine complaining. I would not keep doing it as it probably will beat the bearings out of the engine over time. You need to use first or, if you want to take off in second, you will have to rev it more and slip the clutch. My truck has the Mazda tranny and a 3.08 with stock tires. If I had a 3.55 I am sure I could take off in second. But you have 31s (not sure how much bigger they are). OK, here is a different way to do it: Get tires so big in diameter that it makes your first gear high enough for regular use. You also would gain in ground clearance. I would avoid too much extra tire width though.
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From: redding U.S.A.
Using a gear too tall
hehe, tallpaul, that would be perfect for me.
The only problem is big tires are expensive and i just got these brand new 31"s.
And of course if i got huge tires... i would be wantin for a big lift... then i'd want more power so i'd get lower gears... then i'd have the same prob!
You're absolutely right about just lettin the clutch slip more. But i don't want to be burning clutch for nothing (though maybe that saved shift is worth it..?) so i guess i'll just go back to usin first.
On the topic of gearing... i drove my fathers F-700 deisel dump to the job site today. It's a shift 5 speed. The stick is so loose its almost impossible to tell what gear you're in unless you're used to driving the thing, which i'm not. I started off in 4th gear by accident... and it pulled through it just fine. No load of course, but holy crap! That thing is a monster! Tops out at 70mph pedal to the medal down hill. First gear is good for about 8mph, then you hit redline. Damn.
Dump has a straight six in it too! Although, its a deisel and probably 8 times the size of my 300
The only problem is big tires are expensive and i just got these brand new 31"s.
And of course if i got huge tires... i would be wantin for a big lift... then i'd want more power so i'd get lower gears... then i'd have the same prob!
You're absolutely right about just lettin the clutch slip more. But i don't want to be burning clutch for nothing (though maybe that saved shift is worth it..?) so i guess i'll just go back to usin first.
On the topic of gearing... i drove my fathers F-700 deisel dump to the job site today. It's a shift 5 speed. The stick is so loose its almost impossible to tell what gear you're in unless you're used to driving the thing, which i'm not. I started off in 4th gear by accident... and it pulled through it just fine. No load of course, but holy crap! That thing is a monster! Tops out at 70mph pedal to the medal down hill. First gear is good for about 8mph, then you hit redline. Damn.
Dump has a straight six in it too! Although, its a deisel and probably 8 times the size of my 300
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Post Fiend
Joined: Jan 2000
Posts: 5,860
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From: Metro Detroit (Redford)
Using a gear too tall
Wow, the dump truck would be a blast to drive. You can start it with first gear engaged and it would just get up and walk away.
The gearbox multiplies torque. Whatever your engine torque for the RPM can be multiplied by the gear and the rear end ratio and that will give you rear axle torque. Then I suppose you calculate the proportion of a foot from the axle center to the ground and adjust for torque where the rubber hits the road. YOu can actually graph your trucks torque curves over each gear and road speed and see where the sweet spots are. Mazda has ratios of 3.90, 2.25, 1.50, 1.00, and 0.80. Multiply that by your rear end, then use the torque figures below. Take off maybe 15% for driveline inefficiencies (maybe more, others on the site could tell a better figure). You will find about 3,500 foot pounds in first gear, but way, way more in 4wheel low!
RPM / foot pounds (approx, from '89 brochure for 300 I6)
1000 / 225
1500 / 250
2000 / 265
2500 / 260
3000 / 250
3500 / 230
4000 (why would you rev it that high?
)
I wonder how much torque is going to the wheels in first gear... and how bout first gear 4 wheel low... or... reverse 4 wheel low.... monsterous! [/B]
RPM / foot pounds (approx, from '89 brochure for 300 I6)
1000 / 225
1500 / 250
2000 / 265
2500 / 260
3000 / 250
3500 / 230
4000 (why would you rev it that high?
)
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Thread Starter
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Posting Guru
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From: redding U.S.A.
Using a gear too tall
oh and more on that dump truck!
When you aren't on a steep hill, or aren't carying a load, there is absolutely no reason the use the clutch. All you have to do is stomp it to the floor, shift, then take your foot off and let it snap back.
If you're on flat ground, you can pop the clutch as fast as you can while idling, and it'll get rolling with no problems at all.
The amazing thing is that it'll spin all four tires easily on pavement.
When you're in the dirt, especially going up a hill in first gear, if you let it idle up the hill (and more throttle and it'll loose all traction) you can actually see the wheels slip each time one of the huge six pistons fires.
Its amazing.
When you aren't on a steep hill, or aren't carying a load, there is absolutely no reason the use the clutch. All you have to do is stomp it to the floor, shift, then take your foot off and let it snap back.
If you're on flat ground, you can pop the clutch as fast as you can while idling, and it'll get rolling with no problems at all.
The amazing thing is that it'll spin all four tires easily on pavement.
When you're in the dirt, especially going up a hill in first gear, if you let it idle up the hill (and more throttle and it'll loose all traction) you can actually see the wheels slip each time one of the huge six pistons fires.
Its amazing.
Post Fiend
Joined: Jan 2000
Posts: 5,860
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From: Metro Detroit (Redford)
Using a gear too tall
Even better, hit it in 4 wheel low in reverse (putting the engine weight to work) and do a "can stand" (that's what we called it when we were kids and hopped the rear end of our sting ray bikes in the air).
But yeah, you could do a wheelie just like a farm tractor can flip over backwards when something hangs it up but the wheels keep turning. http://www.iol.ie/~manister/tractort...ctor_wreck.jpg
But yeah, you could do a wheelie just like a farm tractor can flip over backwards when something hangs it up but the wheels keep turning. http://www.iol.ie/~manister/tractort...ctor_wreck.jpg
Post Fiend
Joined: Jan 2000
Posts: 5,860
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From: Metro Detroit (Redford)
Using a gear too tall
He he. I am a low RPM torque freak. Just been reading about tractors. Some of those old 2-cylinder John Deere's (Johnny Poppers) had engines up in the 465 cubic inch range. Wow, 232 cid per cylinder. Talk about torque and lugging power.
I bet the 300 I6 HD would make a great tractor engine. Well, I guess it did since I hear they were installed in combines.
Oh yeah, the noise when you take off in second may be gear rattle. Again, probably the only cure is more rpms or start in first. (Well that puts us back to the original topic after some interesting side discussions.)
I bet the 300 I6 HD would make a great tractor engine. Well, I guess it did since I hear they were installed in combines.
Oh yeah, the noise when you take off in second may be gear rattle. Again, probably the only cure is more rpms or start in first. (Well that puts us back to the original topic after some interesting side discussions.)
Elder User
Joined: Feb 2003
Posts: 871
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From: Coleman, Wisconsin
Using a gear too tall
Originally posted by TallPaul
He he. I am a low RPM torque freak. Just been reading about tractors. Some of those old 2-cylinder John Deere's (Johnny Poppers) had engines up in the 465 cubic inch range. Wow, 232 cid per cylinder. Talk about torque and lugging power.
He he. I am a low RPM torque freak. Just been reading about tractors. Some of those old 2-cylinder John Deere's (Johnny Poppers) had engines up in the 465 cubic inch range. Wow, 232 cid per cylinder. Talk about torque and lugging power.
My favorite 2cyl is the model R. Beast of a tractor. The 80 and the 830 are up there too. (offsrping of the R)
Elder User
Joined: Mar 2003
Posts: 628
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From: Colorado
Using a gear too tall
I'm with Tall_Paul - it ain't a good sound. I get it in 3rd when my r's are too low & it's time to downshift.
I checked out Granny today - 12mph at 3000rpm. With the T-18, 1st is 6.39 (& 3.09 - 2nd) so I guess that's around 5-6,000 ft.lbs....
With the NP 208 in LOW.... 1st tops out at about 3-4 mph @ 3000 rpm. 15 -20,000 ft.lbs. ...??? ( I'm TOTALLY IGNORANT on this subject) - all I know is it has AWESOME PULL in "low -low".
I checked out Granny today - 12mph at 3000rpm. With the T-18, 1st is 6.39 (& 3.09 - 2nd) so I guess that's around 5-6,000 ft.lbs....
With the NP 208 in LOW.... 1st tops out at about 3-4 mph @ 3000 rpm. 15 -20,000 ft.lbs. ...??? ( I'm TOTALLY IGNORANT on this subject) - all I know is it has AWESOME PULL in "low -low".
Last edited by broncr; Apr 17, 2003 at 10:41 PM.