Front to rear gear ratios for pulling competition.

[Supershafts]

Originally Posted by DISTURBED

This is completely incorrect. Even in the OEM stock gears the front is always faster then the rear. If it wasn't then when in 4wd the rear would try to push the front binding the tcase. With the front being faster it pulls the rear along. in pulling we run a faster gear in the front sometimes. Since the back is doing 75% of the work you over drive the front to get more traction from the front end. If the front and rear are close to the same then you only get the same speed out of the front as the rear. By over driving it you are essentially getting more cleat on the ground per foot traveled which would be a greater pulling force to help the rear keep the truck moving. I ran a 36" tire on the front and a 35" on the back will do the same thing. You can safely over drive the front 7%. Some do more but much more then that gets sketchy

With a 44 in back and 35 up front the 4.9 at back and 3.8 ratio holds the same driveline rpm , while the tires are at the same speed at the that diameter.

If you put 44 back and 35 front and run 4.9 back and 4.9 front you are tripping over yourself as the back tire is faster than the the front from it's height, so you need the 4.9 ratio rear and 3.9 ratio front to keep them at the same speed.

If you run the same size tires and run 4.9 and 4.5 then you would or should have less stability, take 2 rear wheel drive vehicles, the front one is spinning it's tires and it is swaying back and fourth because it can't over come the rear that is set and moving slower.

They are both doing the same work, one end is seeing or dragging more weight, that shift from drag pulls the back in and transfers more weight to it unloading the front, but they do the same work as in speed, or you want them to do the same.


As you get further the weight comes on and forces the truck to transfer to the back, you would want lots of weight up front and spring and tire.

But if the vehicle is now sliding along at 20 mph and the rear tires are spinning at 60 mph and the front at 70mph on the same plane then they fight eachother for traction, and as traction comes on braking starts or you'll lose traction.
My idea is you want to get going fast, having say 35 and 35 tires and 4.8 rear and 4.1 front ratio is either binding or breaking traction and forcing wheel spin.

[DISTURBED]

Im not going to argue with you but this has been done for way longer then you have been thinking about it. It works regardless of what reasoning you have. this isn't mud racing where you run a big tire in the back and small one in the front. It doesnt break or bind anything as long as your with in 7-10%

[ClamDigger4]

Originally Posted by Supershafts

With a 44 in back and 35 up front the 4.9 at back and 3.8 ratio holds the same driveline rpm , while the tires are at the same speed at the that diameter.

If you put 44 back and 35 front and run 4.9 back and 4.9 front you are tripping over yourself as the back tire is faster than the the front from it's height, so you need the 4.9 ratio rear and 3.9 ratio front to keep them at the same speed.

If you run the same size tires and run 4.9 and 4.5 then you would or should have less stability, take 2 rear wheel drive vehicles, the front one is spinning it's tires and it is swaying back and fourth because it can't over come the rear that is set and moving slower.

They are both doing the same work, one end is seeing or dragging more weight, that shift from drag pulls the back in and transfers more weight to it unloading the front, but they do the same work as in speed, or you want them to do the same.


As you get further the weight comes on and forces the truck to transfer to the back, you would want lots of weight up front and spring and tire.

But if the vehicle is now sliding along at 20 mph and the rear tires are spinning at 60 mph and the front at 70mph on the same plane then they fight eachother for traction, and as traction comes on braking starts or you'll lose traction.
My idea is you want to get going fast, having say 35 and 35 tires and 4.8 rear and 4.1 front ratio is either binding or breaking traction and forcing wheel spin.

Your numbers are so far off for this situation. It's not even close to the subject at hand. So many pullers with 44" tires and 70mph wheel speed!

phone

[1pieceatatime.]

I can fully appreciate this debate/argument. Mainly because I can see it taking place in my workplace with my old man and older cousin telling me that what has been highly successful for so many people is going break stuff and/or not work.

With the old rule of thumb being 10% difference is acceptable when specing a truck, Its hard for me to believe it could be as potentially detrimental as Marty believes.

I'll be honest, the only thing that has stopped me from trying this with my workstock puller is the fact that I'd still like to give the Drag Strip a whirl.

[zstroken]

4.56 in front, 4.63 in rear, 35" tire in front, 33" tire in back. Full season on it, no issues, and a few of those were some extremely tight tracks. I would be replacing the tcase chain every few years if I continued to do that.

[Rustin]

I'm taking notes. This is great!

[JerrodGlover]

I ran the same size tire front and rear and 4.88 front and 5.13 rear gears. Only problem with it was 5.13's dont live in an 80 with 4 tires on it.

[6.4 F-350]

Originally Posted by JerrodGlover

I ran the same size tire front and rear and 4.88 front and 5.13 rear gears. Only problem with it was 5.13's dont live in an 80 with 4 tires on it.

Do 4.88's have much longer of a life span to speak of in a 80?

[Supershafts]

Originally Posted by ClamDigger4

Your numbers are so far off for this situation. It's not even close to the subject at hand. So many pullers with 44" tires and 70mph wheel speed!

phone

if we can't discuss something and understand the use of numbers in general why have these posts.


just carry on with the same old same old

[ClamDigger4]

Originally Posted by Supershafts

if we can't discuss something and understand the use of numbers in general why have these posts.


just carry on with the same old same old

I can give you numbers all day. That doesn't mean they apply to the situation...

If your slowest wheel speed (lower gear) is always faster than your ground speed How can anything be effected negatively?

phone

[Supershafts]

Originally Posted by 1pieceatatime.

I can fully appreciate this debate/argument. Mainly because I can see it taking place in my workplace with my old man and older cousin telling me that what has been highly successful for so many people is going break stuff and/or not work.

With the old rule of thumb being 10% difference is acceptable when specing a truck, Its hard for me to believe it could be as potentially detrimental as Marty believes.

I'll be honest, the only thing that has stopped me from trying this with my workstock puller is the fact that I'd still like to give the Drag Strip a whirl.

Im not saying detrimental, and yes a 10% difference on dirt isn't going to hurt anything, but if you could plant the tires and drag the weight you'll be working against yourself.
If running a 38 and 35 i would run the ratios to keep them with eachother which would be 3.9 and 3.7
If running 35 and 35 running 4.8 and 5.1 we have a 200 rpm diff which isn't helping if you can plant it.
My thinking is, and i don't follow the rules so excuse me if you can't but i wouldn't want tires that small in diameter.
Having watched TP'ing i see some trucks in some of the same classes use different sizes and widths, which i see as a benefit.

.

[DISTURBED]

Originally Posted by Supershafts

if we can't discuss something and understand the use of numbers in general why have these posts.


just carry on with the same old same old

We are discussing it. Your numbers have nothing to do with sled pulling. Nobody runs a huge tire out back and a small tire in the front and try and get a gear to make them equal. What we do though is run a faster gear in the front or bigger tire in the front and it works. I don't know what kind of back ground you have in motorsports but it does work and has been proven numerous times. They were doing this back in the 80's with cut tires and alky engines. This is nothing new.

[DISTURBED]

Originally Posted by Supershafts

Im not saying detrimental, and yes a 10% difference on dirt isn't going to hurt anything, but if you could plant the tires and drag the weight you'll be working against yourself.
If running a 38 and 35 i would run the ratios to keep them with eachother which would be 3.9 and 3.7
If running 35 and 35 running 4.8 and 5.1 we have a 200 rpm diff which isn't helping if you can plant it.
My thinking is, and i don't follow the rules so excuse me if you can't but i wouldn't want tires that small in diameter.
Having watched TP'ing i see some trucks in some of the same classes use different sizes and widths, which i see as a benefit.

.

35" is the max tire in almost every class except your local stuff

[Supershafts]

Originally Posted by ClamDigger4

I can give you numbers all day. That doesn't mean they apply to the situation...

If your slowest wheel speed (lower gear) is always faster than your ground speed How can anything be effected negatively?

phone

Speed is a factor though dragging a increasing weight, you would want to get to speed as quickly as possible, before you have to resort to wheel speed.

Having a set up where you can cause one to over run the other will cause a traction issue and make wheel spin, which at one point is inevitable, but it is kind of forcing it to happen right off the start.

[DISTURBED]

Originally Posted by Supershafts

Speed is a factor though dragging a increasing weight, you would want to get to speed as quickly as possible, before you have to resort to wheel speed.

Having a set up where you can cause one to over run the other will cause a traction issue and make wheel spin, which at one point is inevitable, but it is kind of forcing it to happen right off the start.

Ummm, you obviously have not watched many pulls. These trucks don't go cleat for cleat down the track. When I leave the line at 5k+ the tires are turning over 40mph. The street tires work off friction

[Nootch]

Got to aggree with Distrubed. Been watching pulls since the mid 80's and they always spun right off the bat in the 4wd class. or at the very least within the first 30 feet.

[1pieceatatime.]

Originally Posted by Supershafts

Im not saying detrimental, and yes a 10% difference on dirt isn't going to hurt anything, but if you could plant the tires and drag the weight you'll be working against yourself.
If running a 38 and 35 i would run the ratios to keep them with eachother which would be 3.9 and 3.7
If running 35 and 35 running 4.8 and 5.1 we have a 200 rpm diff which isn't helping if you can plant it.
My thinking is, and i don't follow the rules so excuse me if you can't but i wouldn't want tires that small in diameter.
Having watched TP'ing i see some trucks in some of the same classes use different sizes and widths, which i see as a benefit.

.

But you can't plant the tires like that.....Even on the stickiest axle twisting track out there.

[Supershafts]

Couldn't it be causing it not to plant though.

I wouldn't pull onto pavement with 36 and 35 tire as it wouldn't work, but on dirt the tire with more will just overcome the other end and make it slip along, which technically would hinder any planting effect that could be made

[Nootch]

Originally Posted by Supershafts

Couldn't it be causing it not to plant though.

I wouldn't pull onto pavement with 36 and 35 tire as it wouldn't work, but on dirt the tire with more will just overcome the other end and make it slip along, which technically would hinder any planting effect that could be made

while that is technically true for a low speed situation where you are working with the sheer factor of the dirt, and thus spinning the front faster than the rear would reduce the friction as you would have passed the sheer point of the dirt.

But the dynamics of sled pulling is different than this. you are not only using the sheer of the dirt, but you are using the resistance to throw it back (equal and opposite direction law) and the dirt loosed up and flung back if i remember correctly gives a fluff layer of marbles that some believe helps the sled along to a certain degree.

while maximum traction is obtained before slip on the road, it is not the case in the dirt.

[1pieceatatime.]

Originally Posted by Supershafts

Couldn't it be causing it not to plant though.

I wouldn't pull onto pavement with 36 and 35 tire as it wouldn't work, but on dirt the tire with more will just overcome the other end and make it slip along, which technically would hinder any planting effect that could be made

You're not on pavement....... IF you plant the tires on a pulling track as hard as you would on pavement, you're not going to go very far.............. Unless the truck has the power and traction to drag the boat from a stand still with the weightbox at the end fully on the pan.