No Such Thing As A Dumb Question

[blade]

another one for you guys.

I am running into some clearance issue when installing the rear disc brake system from Toms. The shock hits the leaf spring because you have to use the offset bracket to move the shock mount over on the rear end. Everything is already powder coated so I don't really want to be grinding anything.

My question is can you change the "clock" location of the caliper bracket so the caliper is facing more towards the front bronco instead of facing the rear, which is what makes it right in the way of the shock. Is it because of the e-brake? Or can brakes not function in that orientation?

You may be able to move the location of the calipers if you can swap them to the opposite side to keep the bleeder in the right position. it may also depend on the brake line lengths reaching the new location.

 

[Wild horse 75]

So this is the mathematical ratio measured out at the wheel due to the differences in gear brands, housings and axles. The differentials are the same front and rear though, right?

While the ratio is not measured out at the wheel. Things like tire pressure and tire wear contribute to the overall ratio your driveshaft sees. And this is precisely why if you look in an owners manual it says 4wd is only to be used when there will be low traction. You need some slip. This is one of the reasons why you see these big diesels at the drag strip running 4 slick leave their transfer cases on the starting line sometimes. Something has to give somewhere. And tire slip is the safest place.

 

[Soylent]

Got it, I hope So I would assume you try to match them as close as possible like 4.11 rear and 4.10 front. Not something like 3.50 front and 4.11 rear.

 

[Wild horse 75]

Got it, I hope So I would assume you try to match them as close as possible like 4.11 rear and 4.10 front. Not something like 3.50 front and 4.11 rear.

That’s the best you can do.

 

[jamesroney]

That’s the best you can do.

We can do better.

This is a safe space, so there is not supposed to be any judgement. So there may not be any dumb questions, but there are sure some dumb answers here. I don't know how to tell you that your are wrong without telling you that you are wrong. A alternative definition of "safe-space" is echo chamber.

@DirtDonk you were doing fine on the gear ratio thing when you pointed out the ring and pinion tooth counts. That defines the ratio. The Ford 9 inch rear axle ratio in an Early Bronco uses 37 teeth on the ring gear, and 9 on the pinion. This math results in 37/9 = 4.111111 So a Ford 9 inch rear end in that ratio is called "Four-Eleven". The Front drive axle on your Early Bronco with a Dana 44 is equipped with 45 teeth on the ring gear, and 11 on the pinion. 45/11 = 4.090909 We name this ratio "Four-Oh-Nine" The Dana 30 in your Early Bronco will be equipped with a front axle with a ring gear of 41 teeth, and a pinion of 10. This results in 41/10=4.1 We name this ratio "Four-Ten"

The notion that the ring and pinion tooth counts have something to do with the OEM is of course true. BUT, it is not a constraint. For example, you can/could buy an Auburn Gear 342066 Ring and pinion in 41-10 for your Ford 9 inch. So it is entirely possible to put 4.10 gears in the rear. You can also put a 41-10 ring and pinion in your front Dana 44. Then the two would match EXACTLY. But nobody does that. Mostly because the 9 tooth pinion in the 9 inch is stronger than the 11 tooth pinion. But obviously, also because it would be unusual. But the Dana 60 rear is 41-10 and it is also paired with the 4.09 front in the F250. But the real reason is that it doesn't matter.

So the "best you can do" is to match ratio exactly. EXCEPT that the "best you can do" is not the best for everything. Most of the mud racers that I know like to run larger tires in the rear, and smaller steering tires in the front. They like to run a lower gear ratio up front, (higher numerically) They claim that this allows the front axle to "pull" harder than the rear, and results in less oversteer. My manufacturing Engineering colleagues would say that 45/11 is more manufacturable, since the tooling is already invested. And the NVH Drivetrain engineer might say that 4.11 is a hunting gear set that is quieter. But the fact that the Dana 44 ran for 53 years as a 4.09, and then graduated to 4.10 for the past 20 years says otherwise. The fact of the matter is that there are a wide variety of competing design and process constraints that cause the manufacturer to select the ring and pinion counts. Cost is always a factor. But also noise, heat, tooling, product inertia etc. because the final drive number doesn't matter.

Rounding certainly does happen. In catalogs, in marketing literature, and in product descriptions. And it's not really rounding. You can find a nice set of used Dana 30 Bronco Gears from one of the best vendors on the planet, and the ebay listing will say "4.09" gearset. Then you can look at the picture and see the Dana Spicer tooth counts stamped into the gear. 41-10. 41/10 does not round to 4.09. 4.111111 and 4.090909 and 4.1 all round to 4.1. And then to 4.
Many people will round to the nearest thing that they like to pronounce. Drives me out of my mind.
4.56 is another problematic ratio.
41/9 = 4.555555 rounds to 4.56.
50/11 = 4.545454 rounds to 4.55
32/7 = 4.57142 rounds to 4.57
Motive gear sells BOTH the 9 inch Bronco gear set as an F9-456 for $307.99 they also sell the F890457 for $359.99

Gotta get back to work.

If you want to know the truth about drive ratio and tire diameter...someone needs to ask. But that is also wrong...

 

[NickC24]

Nick,
I've been here over a decade, and I have seen how some other sites are and there is some real a..holes out there but I would think this would be the last forum for the need of a "safe space".
Yes, there might be some good-natured ball busting but usually that's in the "Off Topic" section.

For sure. I didn't mean that this was needed, just thought it would be a good open discussion thread for people to come to learn about different topics but you're right. That's kinda the purpose of this entire forum.

 

[NickC24]

I have another. When powder coating the front and rear ends do you coat the mating surface of the covers or do you leave them bare metal. Not sure what seals better or if it even matters.

 

[ba123]

The real reason for the different gear ratios in “our” front and rear differentials, is because they are completely different designs.
The rear differential is a Ford 9 inch, the front is a Dana design axle. They are not nearly the same, and that’s just how they came up with ratios.
And some actually were even different among the same ones. For example, one Dana 44 from the factory might have, one ratio, while the gears you can buy for it through the aftermarket are a number or two off.

Besides that, not all trucks do have different ratios. My F350 has the same ratios front and rear because it has Dana 60s front and rear.

Exactly…and because of that different design, they have different pinion sizes and different gear sizes and those together are what makes the ratio and unless they are the same, they can’t have the same ratio.

 

[ba123]

another one for you guys.

I am running into some clearance issue when installing the rear disc brake system from Toms. The shock hits the leaf spring because you have to use the offset bracket to move the shock mount over on the rear end. Everything is already powder coated so I don't really want to be grinding anything.

My question is can you change the "clock" location of the caliper bracket so the caliper is facing more towards the front bronco instead of facing the rear, which is what makes it right in the way of the shock. Is it because of the e-brake? Or can brakes not function in that orientation?

You could try swapping the sides, use the drivers bracket on the pass side and the pass on the drivers side. Of course, the parking cables would exit towards the back, but that might work anyway and I did consider doing this myself.

 

[Glass Pony]

I have another. When powder coating the front and rear ends do you coat the mating surface of the covers or do you leave them bare metal. Not sure what seals better or if it even matters.

Never powder coat or paint mating surfaces. Also if you are fabricating a part to be powder coated and it has holes drilled in it for bolting, drill the holes an extra .005"-.010" oversized. The powder is pretty thick sometimes.

 

[Soylent]

We can do better.

This is a safe space, so there is not supposed to be any judgement. So there may not be any dumb questions, but there are sure some dumb answers here. I don't know how to tell you that your are wrong without telling you that you are wrong. A alternative definition of "safe-space" is echo chamber.

@DirtDonk you were doing fine on the gear ratio thing when you pointed out the ring and pinion tooth counts. That defines the ratio. The Ford 9 inch rear axle ratio in an Early Bronco uses 37 teeth on the ring gear, and 9 on the pinion. This math results in 37/9 = 4.111111 So a Ford 9 inch rear end in that ratio is called "Four-Eleven". The Front drive axle on your Early Bronco with a Dana 44 is equipped with 45 teeth on the ring gear, and 11 on the pinion. 45/11 = 4.090909 We name this ratio "Four-Oh-Nine" The Dana 30 in your Early Bronco will be equipped with a front axle with a ring gear of 41 teeth, and a pinion of 10. This results in 41/10=4.1 We name this ratio "Four-Ten"

The notion that the ring and pinion tooth counts have something to do with the OEM is of course true. BUT, it is not a constraint. For example, you can/could buy an Auburn Gear 342066 Ring and pinion in 41-10 for your Ford 9 inch. So it is entirely possible to put 4.10 gears in the rear. You can also put a 41-10 ring and pinion in your front Dana 44. Then the two would match EXACTLY. But nobody does that. Mostly because the 9 tooth pinion in the 9 inch is stronger than the 11 tooth pinion. But obviously, also because it would be unusual. But the Dana 60 rear is 41-10 and it is also paired with the 4.09 front in the F250. But the real reason is that it doesn't matter.

So the "best you can do" is to match ratio exactly. EXCEPT that the "best you can do" is not the best for everything. Most of the mud racers that I know like to run larger tires in the rear, and smaller steering tires in the front. They like to run a lower gear ratio up front, (higher numerically) They claim that this allows the front axle to "pull" harder than the rear, and results in less oversteer. My manufacturing Engineering colleagues would say that 45/11 is more manufacturable, since the tooling is already invested. And the NVH Drivetrain engineer might say that 4.11 is a hunting gear set that is quieter. But the fact that the Dana 44 ran for 53 years as a 4.09, and then graduated to 4.10 for the past 20 years says otherwise. The fact of the matter is that there are a wide variety of competing design and process constraints that cause the manufacturer to select the ring and pinion counts. Cost is always a factor. But also noise, heat, tooling, product inertia etc. because the final drive number doesn't matter.

Rounding certainly does happen. In catalogs, in marketing literature, and in product descriptions. And it's not really rounding. You can find a nice set of used Dana 30 Bronco Gears from one of the best vendors on the planet, and the ebay listing will say "4.09" gearset. Then you can look at the picture and see the Dana Spicer tooth counts stamped into the gear. 41-10. 41/10 does not round to 4.09. 4.111111 and 4.090909 and 4.1 all round to 4.1. And then to 4.
Many people will round to the nearest thing that they like to pronounce. Drives me out of my mind.
4.56 is another problematic ratio.
41/9 = 4.555555 rounds to 4.56.
50/11 = 4.545454 rounds to 4.55
32/7 = 4.57142 rounds to 4.57
Motive gear sells BOTH the 9 inch Bronco gear set as an F9-456 for $307.99 they also sell the F890457 for $359.99

Gotta get back to work.

If you want to know the truth about drive ratio and tire diameter...someone needs to ask. But that is also wrong...

I think I’m getting it. That last pic you posted from NE is a “Four-Ten”

 

[jamesroney]

You could try swapping the sides, use the drivers bracket on the pass side and the pass on the drivers side. Of course, the parking cables would exit towards the back, but that might work anyway and I did consider doing this myself.

It works fine. Here’s my Explorer discs with caliper in the front, and factory shock mounts toward the rear. (I know it’s a 60, but it’s the same idea.)

 

[NickC24]

It works fine. Here’s my Explorer discs with caliper in the front, and factory shock mounts toward the rear. (I know it’s a 60, but it’s the same idea.)

Awesome, thanks. Im gonna try it out.

 

[jamesroney]

While the ratio is not measured out at the wheel. Things like tire pressure and tire wear contribute to the overall ratio your driveshaft sees.

Tire pressure? Are you sure about that? Radial tires don't work that way.

 

[ba123]

Tire pressure? Are you sure about that? Radial tires don't work that way.

He prob means like the same as having your rear tires a different diameter (or one end flat) than your front would have the same effect as a different ratio.

 

[jamesroney]

He prob means like the same as having your rear tires a different diameter (or one end flat) than your front would have the same effect as a different ratio.

But it won't. Do you think changing your tire pressure changes it's rolling circumference?

Asked a different way: If your 35x12.50x17 inch tire goes 600 revolutions per mile at 50 psi...how many revolutions per mile at 10 psi?

(more, less, or the same?)

 

[NickC24]

Never powder coat or paint mating surfaces. Also if you are fabricating a part to be powder coated and it has holes drilled in it for bolting, drill the holes an extra .005"-.010" oversized. The powder is pretty thick sometimes.

So how do you make sure the powder coat gets far enough in so that there is no bare metal. Also I feel like it would be worse to have a line on the mating surface where the powder coat stops. Cause then you have two uneven surfaces for the gasket to seal?

 

[ba123]

But it won't. Do you think changing your tire pressure changes it's rolling circumference?

Asked a different way: If your 35x12.50x17 inch tire goes 600 revolutions per mile at 50 psi...how many revolutions per mile at 10 psi?

(more, less, or the same?)

If you take your 35” tire and let all the air down to 10 psi and do so on both sides of that axle, or all around for that matter, will your vehicle not be slightly lower? Therefore, they will take more revolutions per mile. Maybe not a ton, but they will. Think of it this way…what if you slash your tire? It’s still a 35” tire!

James, I know you’re the man so maybe your cars float through the air, but mine don’t!

 

[jamesroney]

If you take your 35” tire and let all the air down to 10 psi and do so on both sides of that axle, or all around for that matter, will your vehicle not be slightly lower? Therefore, they will take more revolutions per mile. Maybe not a ton, but they will. Think of it this way…what if you slash your tire? It’s still a 35” tire!

James, I know you’re the man so maybe your cars float through the air, but mine don’t!

Nope. This is where the facts destroy the assumptions.

Everybody always thought that the distance traveled by a tire was proportional to it's rolling radius. So if you measure from the ground to your axle center...on a 35 inch tire...it is 17 inches. If you deflate your tires by 2 inches, to a rolling radius of 15 inches, The revolutions per mile are UNCHANGED.

Once you think about it...you will say: "Wow...that James is a genius." But I'm really not. And in this thread, I'm not allowed to point out anything dumb...

So here's the deal. Back in the early 1980's the Military developed CTIS (Central Tire Inflation System) on the HMMWV. They ran with 37 inch Goodyear Bias Ply tires. The tire inflation could be adjusted in the cab. In order to keep speed with other vehicle in a convoy the operator would adjust his indicated speed to offset his tire inflation. In 1990, a new radial tire was deployed during desert storm. Operators were shocked that they could maintain convoy speed and speedometer reading REGARDLESS of air pressure. This has been proven on video. Changing the rolling radius of a radial tire does NOT change the distance it travels per revolution. There was a youtube of a a test track and a video camera counting rotations verus travelling a set distance. It's very enlightening.

The reason is because your concept of the movement dynamics of a radial tire is flawed. If you model the tire as a hula-hoop, with springs extending from the rim to a center hub...you can see that one rotation of the hula hoop travels the same distance no matter how low the center hub sits. And that's what happens with a radial tire. The carcass is basically a huge chunk of in-compressible belts under the tread...with an inner bead riding inside of it. All of the squirming happens in the sidewall.

I admit that it took me a while to get my head around this...So enjoy!

 

[ba123]

Nope. This is where the facts destroy the assumptions.

Everybody always thought that the distance traveled by a tire was proportional to it's rolling radius. So if you measure from the ground to your axle center...on a 35 inch tire...it is 17 inches. If you deflate your tires by 2 inches, to a rolling radius of 15 inches, The revolutions per mile are UNCHANGED.

Once you think about it...you will say: "Wow...that James is a genius." But I'm really not. And in this thread, I'm not allowed to point out anything dumb...

So here's the deal. Back in the early 1980's the Military developed CTIS (Central Tire Inflation System) on the HMMWV. They ran with 37 inch Goodyear Bias Ply tires. The tire inflation could be adjusted in the cab. In order to keep speed with other vehicle in a convoy the operator would adjust his indicated speed to offset his tire inflation. In 1990, a new radial tire was deployed during desert storm. Operators were shocked that they could maintain convoy speed and speedometer reading REGARDLESS of air pressure. This has been proven on video. Changing the rolling radius of a radial tire does NOT change the distance it travels per revolution. There was a youtube of a a test track and a video camera counting rotations verus travelling a set distance. It's very enlightening.

The reason is because your concept of the movement dynamics of a radial tire is flawed. If you model the tire as a hula-hoop, with springs extending from the rim to a center hub...you can see that one rotation of the hula hoop travels the same distance no matter how low the center hub sits. And that's what happens with a radial tire. The carcass is basically a huge chunk of in-compressible belts under the tread...with an inner bead riding inside of it. All of the squirming happens in the sidewall.

I admit that it took me a while to get my head around this...So enjoy!

That's amazing and totally makes sense at normal speed which makes the tire expand to it's normal radius and moves any air and really does "float" but I'd bet that below a certain speed, it doesn't.

I'm curious now, thanks for the info...I'll have to go video searching!

Thanks for the enlightening.