need new gears

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figure im going to go with 5.29's.

that's going to be pretty weak for a toyota gear set....personally what has worked pretty good for me is using factory (fine spline) 4.10 or 3.70's and getting my gearing out of the transmission (sm420) and t-case.....you can get 3.70 3rd's for $75 all day long.....4.11's more like $150
 
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that's going to be pretty weak for a toyota gear set....personally what has worked pretty good for me is using factory (fine spline) 4.10 or 3.70's and getting my gearing out of the transmission (sm420) and t-case.....you can get 3.70 3rd's for $75 all day long.....4.11's more like $150
Mookie can you explain "weak" I thought that 5.29's will get me the lowest crawl with my sm 420 and stock transcase. I know that the 4.11 worked well with crawling . but while im opened up should upgrade.. Rick
 

Tapage

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Mookie can you explain "weak"

that's coz the pinion are in the 5.29 even smaller than in the 4.88 .. making it more weak .. and actually are a hard fit in a SF rear axle ..
 

Poser

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Why did the pinion fail?

not sure why the pinion failed , but i do believe if it were a fine spline it would had a better chance.. maybe a loose nut behind the wheel :)


Do you own an FSM?
not sure what an FSM is, but I googled it and came up with

Flying Spaghetti Monster?

Do you own the tooling for doing the job?

I am a machinist and do own a dial indicator and can fab up the spanner wrench for the ring gear side to side adjustment

any whoo do I just replace the 4.11 gears with 4.11 with fine spline or go with 4.88 with fine spline? thanks for any input and would certainly like to know what a FSM is...capt
 

65swb45

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capt. rick, perhaps you do not realize it, but Poser is doing you an enormous favor by asking you to focus on the most important question first....WHY?

You really SHOULD explore what caused the pinion to fail in the first place and address THE REAL PROBLEM rather than just addressing THE MANIFESTATION of the problem. That way, when you fix the truck, it will stay fixed.

Is the truck lifted?
SUA or SOA?
Stock powertrain?
What is the pinion angle relative to the driveshaft?
What size tires are you trying to push?

Sometimes I just answer the question asked. Mostly I prefer Steve's method of drawing out the information needed to provide a truly useful answer.:)

Best

Mark A.
 
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capt. rick, perhaps you do not realize it, but Poser is doing you an enormous favor by asking you to focus on the most important question first....WHY?

You really SHOULD explore what caused the pinion to fail in the first place and address THE REAL PROBLEM rather than just addressing THE MANIFESTATION of the problem. That way, when you fix the truck, it will stay fixed.

Is the truck lifted?
SUA or SOA?

yes the truck has SOA and stock springs

Stock powertrain?

stock 2f With sm420 and stock TC

What is the pinion angle relative to the driveshaft?

the pinion angle is almost straight in line with drive shaft

What size tires are you trying to push?

I have 39s

Sometimes I just answer the question asked. Mostly I prefer Steve's method of drawing out the information needed to provide a truly useful answer.:)


Best

Mark A.

I dont mean any disrespect to poser, just did not have the answeres, and am new to all the abbreviations here on the forum,,,
I do believe the sand that i was in, in conjunction with being on such a steep incline and little to much skinny pedal had alot to do with pinion breaking. Your correct when you say fix it to stay fixed thats why i look here for all info y'all have to offer. thanks Rick
 
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I dont mean any disrespect to poser, just did not have the answeres, and am new to all the abbreviations here on the forum,,,
I do believe the sand that i was in, in conjunction with being on such a steep incline and little to much skinny pedal had alot to do with pinion breaking. Your correct when you say fix it to stay fixed thats why i look here for all info y'all have to offer. thanks Rick

Do you have a traction bar to control axle wrap?
 

John Smith

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no, but it is on the list and the list seems to be getting long and expensive

Your lack of a traction bar is what caused the pinion to fail due to axle wrap. It happens all the time on SOA trucks without them. Be aware that to install 4:88 or 5:29 gears into your semi-float axle you will need to remove part of the ring gear teeth to get the cross shaft into the carrier. Some people, with good reason, refuse to setup 5:29 gear sets into semi-float axles because of the huge amount of tooth that must be removed.

I would personally stay with stock fine spline gear sets since you already have the granny low in the SM420 for going slow.
 

Poser

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yes the truck has SOA and stock springs





And now we see why your pinion broke.


Install any gear ratio/pinion spline combination into that same scenario and the end result will be identical; more broken junk. Spring-over axle wrap causes drive shafts to bind at the pinion, twisting them off every time.


Budget in to your repairs a properly built and installed axle wrap control device, or you will become very proficient at replacing gear sets.


If you are going to spend the money on new gears and bearings, I would suggest picking up a Factory Service Manual so that you can reference it for the important information contained within specific to your task.



:beer:
 
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I have to disagree with Steve on this some. In the rocks... yes, SOA needs antiwrap. But in use where traction is lower and or where throttle is not full open from a standing start, an SOA rig can live without antiwrap bars quite well. My uses and that of those who run with me, calls for large tires and SOA configuration.... often calls for a lot of power. But I can not remember the last time I saw a pinion fail due to spring wrap where it could not also be directly attributed to stupidness behind the steering wheel.

Some of us do have antiwrap bars... some have springs which resist wrap very well. Some have neither.

It depends a LOT on how the rig is tasked when you are determining how important an antiwrap bar is. I can't think of any time that a PROPERLY designed and installed antiwrap bar is a bad thing. But it is not always a requirement.


Mark...
 

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