Birty Dastards Jeep Club

Tech Forum => Workshop => Topic started by: Anonymous on September 25, 2006, 06:30:14 PM

Title: Broken Pinion ... why ?
Post by: Anonymous on September 25, 2006, 06:30:14 PM

OK, heres one for you techies, the FJ is a spring over axle (SOA) leafer with a 5.0l V8 and 35/14.5/15 mud terrain type tyres. On a recent trip to France whilst driving a steepish hill in sand the rear pinion broke - Why?

Firstly it was not caused by the power of the engine or the size of the tyres - I actually know the answer but the reason I'm asking is because I want to know if you guys can come up with the answer and then more importantly debate its cure - over to you

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Post by: greggmo on September 25, 2006, 06:42:45 PM

thats a strange one. maybe the driveline angle or did the axle get to skip on the sand?

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Post by: chrisjones on September 25, 2006, 06:49:43 PM

Did the tyres dig in, cause axle wrap and over stress the pinion?

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Post by: isle of man on September 25, 2006, 06:52:05 PM

type of axle? what soa leaf set-up?



peter henry

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Post by: Anonymous on September 25, 2006, 06:59:33 PM

Driveline angle is fine until the axle wrap which then caused the driveline to bind and the pinion to shear so Greggmo and Chris you were both right

(Pete the axles are stock FJ40 - I dont understand what you mean by 'what SOA leaf setup')

So whats the cure for axle wrap ?

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Post by: greggmo on September 25, 2006, 07:14:42 PM

you would need a similar set up to any coil sprung truck really. some kind of upper arms attached to both axle and chassis. have a look on some of the us sites and you will see dozens of em done soa.

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Post by: isle of man on September 25, 2006, 07:18:47 PM

matt,
have a look at this...............
http://http://www.pirate4x4.com/forum/showthread.php?t=504288



peter henry

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Post by: Anonymous on September 25, 2006, 07:18:53 PM

Once again the correct answer, however I already have one of these arms fitted !!!!

I've scoured the sites and come up with conflicting ideas on the best design, best location, best material, best joint etc etc - Have any of you any experience with axle wrap and which design of bar cured it ?

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Post by: isle of man on September 25, 2006, 07:23:43 PM

you may have to move the arm 6 degrees from it's current location........or put the new uj's from tom woods into your propshaft.



peter henry

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Post by: Anonymous on September 25, 2006, 07:28:24 PM

Quote from: "isle of man"

you may have to move the arm 6 degrees from it's current location........or put the new uj's from tom woods into your propshaft.



peter henry

Why 6 deg, seems very accurate if you haven't seen setup ?

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Post by: greggmo on September 25, 2006, 07:29:06 PM

http://www.4x4wire.com/jeep/tech/susp/axlewrap/ (http://www.4x4wire.com/jeep/tech/susp/axlewrap/)

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Post by: isle of man on September 25, 2006, 07:34:32 PM

Quote from: "matt the sign"

Quote from: "isle of man"

you may have to move the arm 6 degrees from it's current location........or put the new uj's from tom woods into your propshaft.



peter henry

Why 6 deg, seems very accurate if you haven't seen setup ?

because it's not uncommon for people to set them to low and not allow for the warp........



peter henry

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Post by: Anonymous on September 26, 2006, 10:47:31 AM

Thanks for all your input guys