Gear Setup Question

[sdreaden]

I am swapping out the carrier in my 9" rearend. This rearend was rebuilt with a spool a couple of years ago but not many miles on it. The tooth pattern on the ring gear is currently on the toe. So question is when setting the gears up in a new carrier, should I try correct the tooth pattern or match the pattern that has already developed on the Toe? What are the reprocussions of the current wear pattern if I change it now?

 

[berdeman]

When setting up a new carrier you will never be able to "exactly" match the old pattern. Sounds like it was not set up correctly the first time. Bring the pattern to spec and keep an eye on your backlash (you may need to re-shim your pinion support). Also you should heat cycle it (break it in) to the new pattern.

 

[broncnaz]

If I remember correctly toe is ok for 9in gear pattern. Yoy really shouldnt need to change anything other than the carrier and set preload. Doesn treally make much a differance but as was said you always need to 'break in" new gear setup even with old gears.

 

[chrlsful]

A local worked on mine. It sat for a coupla mo & when I drove it, & it was dry - he forgot to lube it up when he tried to fit in my lok rite (couldn't do it either). I had lock up alright! at 35 m/hr in traffic. Luck I wasn't goin faster. RRRrrt!
I put in the gears from the '70. Ben drivin for 1 yr. I don't know what break in is. What do U mean by heat cycle? Drives good; did my driveways all winter, skids logs & hauls rock even better...no comprende'.
Thanx

 

[broncnaz]

Its just better to be safe than sorry.
Break in for gears is usually drive it for about 20 minutes(normal driving no big hills with long pulls) Then let it cool down and drive it again. Do this for at least the first 100 miles athough 500 would be better then change the oil. Kinda like engine break in. If you just drive the snot out of it the gears could get to hot but used gears usually are not quite as suspetable to this as new gears are.
The last few 9in's I've set up with used gears only got slightly warm during this time. One of the first ones I did seemed to get pretty hot with just 20 miuntes of driving but I was aslo breaking in a real tight LS so that may have added to the heat.
If you dont change the pinion shims then the wear pattern shouldnt really change so not much heat will be built and used gears are already broke in so to speak.

Chrisful did you actually swap gears or just swap center sections? swapping center sections makes no differance as none of the setting are changed. Most of the gear failure issues I've seen tend to be on new trucks that haul big loads for long periods of time as they tend not to get a break in period. Most of the time when people get new vehicles they drive them easy so break in just happens.

 

[chrlsful]

If you dont change the pinion shims then the wear pattern shouldnt really change so not much heat will be built and used gears are already broke in so to speak.

Wow, OK, went thru some changes there. I just threw in the whole thing from the '70 to the '77. The car blew a head gasket so I had to put the yard bird on the road. Don't really know what I'm doing so reading the post scared me.
No, didn't 'change' anything, just swaped them. Of course THIS time I lubed it!
The rig has seen more hwy mi in the last yr than all it's other 27 yrs in my ownership. Doesn't seem baked...how would I know, now, if it's dammaged...sound?
Thanks for your replies (both now and in the past).

 

[broncnaz]

Dont worry swapping the whole thing is fine like you said this one has lube. in most cases gear failure may be more of setup issues than actual break in procedure Although even then a less than good setup would probably last if broken in properly.

The last gears I reused were in my 73 and it has over 320,000 miles on the gears they looked fine and should go a lot longer.

 

[chrlsful]

I remember setting one up...the guy used the bluing and spun & adjusted them untill meshing properly. I didn't think I hadda go through all that, but wasn't sure what I'd done when reading the topic on the 'Bronco Tech' forum's (what 2 call it) content page/recient posts page, then comming here to C the above posts.
Thanks, see you on the forums,