Competition Need Sled Pulling Advice

[Stamey]

I have been pulling with my 99 2500, QC, SWB. It has a 2001. 5 D70 with p-lok in it and open D60 in front. DTT automatic with billet shafts, HD transfer case, and stock u-joints. Running Pro Comp 315/75R16 All Terrain tires. Adjustable hitch height, set at 26". No extra weights in front or rear.

The second time I pulled I broke the left axle. It came apart just outside the P-lok. Fixed that with an axle out of my 99's old rear, then got some Tough Country ladder bars to prevent wheel hop. I have no blocking of the rear suspension at this time.

Third time I pulled, I weighed in at 7,020 lbs, and even forgot to turn the Comp up from 1x1, but the spider gears in the P-lok exploded at the end of the pull. Both axles look good this time.

Have already been advised I should get a D80 or AAM 11. 5". Am looking.



What I need to know:

1. Am I doing something wrong?

2. Could there be somehting wrong with my setup?

3. Could the 315 tires be too big for pulling?

4. Will lowering my hitch height help take some load off the rear and put less strain on it?



Carnage: http://new.photos.yahoo.com/impresn/album/576460762332594632#page1



Video of the third pull, where the spiders gears broke (if it has been approved by the moderators of that site): http://video.thedieselgarage.com/video/f55f6029-49e5-42fb-a51c-986b0177e48f.htm



I also drag race and drive on the street, so I need to find solutions that work for all environments.

Any advice will be appreciated.



Thanks,

Chris

 

[jwilliams3]

A sagging suspension is carnage waiting to happen (in your case it did).

Block it up.



Get some 33's (my opinion) all terrains preferably.



You can lower your hitch but really thats just a band-aid if you're not re-enforcing the rear suspension. Lowering is one of those things you do when the track conditions favor it (ie tough tight track or super heavy sled).



Your horsepower will still pull the trucks suspension down.

 

[Sled Puller]

The Dana 70 yoke will break next, the Power Lock wont take it.



You shouldn't ever pull on 315s with a 26" hitch when you have small parts.

 

[Stamey]

Does the sagging suspension make that much of a difference where the spider gears are involved?



I did see a couple of fellows with a removable block setup at the last pull. I'm going to build something like that for my truck very soon. They just jacked up the truck, by the hitch, to add or remove the blocks. I had the idea, but had not worked out the details of building it yet. Perhaps I should get that done before I pull again.



Thanks,

Chris

 

[Stamey]

The Dana 70 yoke will break next, the Power Lock wont take it.



You shouldn't ever pull on 315s with a 26" hitch when you have small parts.

So what adjustments do you rcommend? Will lowering the hitch help? If so, how low should I go?

What size tires should I run?

jwilliams recommends 33's, and the 315's are 31" high. Just seems like rotating the large tires puts more strain on the rear end parts.

I probably will not be able to switch out tires very soon. I do have some Desert Duelers in 265/75, 2 new 2 wornout. That would be a cheaper replacement.



Thanks,

Chris

 

[Sled Puller]

Put the bald 265s on the rear, that will help your spiders. You dont need a lot of tread on the rear tires, the sled plants them pretty good.



Not sure how strong your ladder bars are, they may be flexing enough to really not be working.

 

[Stamey]

So blocking will be a good thing, and smaller tires, if I can do that. I was planning to go with 295 or smaller once I wear these 315's out. I'd like to remove the leveling kit I have on the front since it changes how the truck sits when I tow as well. But back to the subject.

Will lowering my hitch height help? How much should I lower it? I can get it down to 6" off the ground, if necessary.

I did not feel any bouncing near the end on my last pull, so it seems liek the ladder bars are working.

I suppose I still need to be watching out for a D80 or AAM 11. 5", but I am OK with not pulling as far as I could, if I don;t break anything. (I'm still learning this sport)



Thanks,

Chris

 

[jwilliams3]

Chris,

Good call on getting rid of the leveling kit.



Remember the more you lower that hitch the heavier the sled gets (or more dead weight to drag).

Lowering the hitch however may let you free up some wheel speed and unload the tires a bit. I wouldnt go under 22" though.

With your kind of horsepower lowering will not help a whole bunch with suspension squat...

 

[Stamey]

Picked up some rect. tubing this morning. Will start on the blocks this evening. Won't pull again without them.

Was thinking, even if I get a D80, it's the same p-lok as the D70, right? I mean, it might have 35 spline axles, but will still be the same otherwise, as far as the spider gears, right? If that's the case, what does the D80 give me in the area of the carrier?



Other D80 advantages, as I understand it, are . 5" larger ring gear, a "much" bigger pinion (have not heard actual size), and the larger number of splines on the axles (I understand they are all 1. 5" dia. axles).



I appreciate you guys' advice in this area.



Thanks,

Chris

 

[MMiller]

You'll just end up breaking the spiders in the dana 80. I'd get a detroit locker, and throw away the limited slip. Dunno what I would do with axles though. I would definatly upgrade, because a broken axle shaft can take out the detroit. A buddy of mine went Detroit, and Yukon axles in his 80(after destroying a LS), and only got a few hooks before one of the new axles broke. Its always a smooth truck, no hopping/bouncing, and smooth off the line. I don't know what to think about the Yukon breaking or what to advise.



Dropping the hitch will give more advantage to the sled. Block the suspension, make sure the ladder bars are holding, and leave the hitch at 26".



Michael

 

[Bobcat698]

You'll just end up breaking the spiders in the dana 80. I'd get a detroit locker, and throw away the limited slip. Dunno what I would do with axles though. I would definatly upgrade, because a broken axle shaft can take out the detroit. A buddy of mine went Detroit, and Yukon axles in his 80(after destroying a LS), and only got a few hooks before one of the new axles broke. Its always a smooth truck, no hopping/bouncing, and smooth off the line. I don't know what to think about the Yukon breaking or what to advise.



Dropping the hitch will give more advantage to the sled. Block the suspension, make sure the ladder bars are holding, and leave the hitch at 26".



Michael

Amen!

I broke 2 sets of spider gears in my Dana 80, then got a Detroit.

I broke both axles at once in the 80 with a bad hop which ruined the Detroit

I put new Yukon axles in, hooked 3 times with NO hopping and twisted the left rear BADLY. They refunded my money at RR&P.



I currently have quite a few hooks on my stock axles but will be getting a set of SCS or Haisley axles this winter.

 

[BigBadDodge]

The Haisley axles are awesome, but if you can afford it or get a sponsor to help out. I would recomend the ARB over the Detroit, IMO its stronger and especially for you guy's who are still daily driving them.



BBD

 

[thekidfan]

So what adjustments do you rcommend? Will lowering the hitch help? If so, how low should I go?

What size tires should I run?

jwilliams recommends 33's, and the 315's are 31" high. Just seems like rotating the large tires puts more strain on the rear end parts.

I probably will not be able to switch out tires very soon. I do have some Desert Duelers in 265/75, 2 new 2 wornout. That would be a cheaper replacement.



Thanks,

Chris

315/75's aren't 31" tall tires usually they are around 34. 5" 265's are 31"

 

[Stamey]

315/75's aren't 31" tall tires usually they are around 34. 5" 265's are 31"

You're right. My bad. They are 34. 60" tall. My 265s should be 31. 65" tall.



The P-lok has been rebuilt and installed. Boy is that unit TIGHT. I may have to add another bottle of fric mod.

I am going to complete the blocks this week.



Thanks,

Chris