Ok fellas, so here's the deal.

Last fall I replaced the 2.73 ratio with a 3.50 ratio in my '79 F-100 with the Inline 6. Love it. Anyway, my brother was cruising down a back road around 80k/h and all of a sudden there was a loud bang and the truck quit going. Further inspection revealed it was in the rear end, and I just got it apart today.

It appears that I've sheared off the spider gears somehow! I know they need to be replaced, but I was hoping for some input on what could have caused this so I don't slap it back together and do the same thing again.

They are the stock 28 spline spider gears that came with the truck, because the donor 3rd member had 31 spline axles. I just took the outer housing and ring/pinion from the donor, and the carrier from my truck. Slapped the new ring/pinion onto the old carrier, and set the backlash. Tossed it in the truck, and it drove great. The backlash still seems fine, its just that as you can see, the spider gears are 'well worn'.

Jer

 

Causes? Hahahaha!! Your brother, for one......

Seriously, a bent axle, bent axle shaft, heavy duty off-roading (brother again) at high speed, big tires and taking a corner too fast all would contribute to pooched spiders.

What was the pinion gear shims/play like when you slapped it together?

 

You are referring to the differential gears, not the spider gears.

9" axle shafts pass thru the differential (aka axle) gears that have either 28 (C8OZ-4236-A) or 31 (C9AZ-4236-A) splines.

Spider gears (1-C9AZ-4215-A kit) makes no difference if the truck has 28 or 31 splines or a Limited Slip differential.

4 pinion Limited Slip takes two of these spider gear kits.

When you consider that these parts are probably the originals, making them 38 years old, it's no wonder they stripped.

Metal parts like differential and spider gears can crystalize, then strip. When axle shafts crystalize, they snap in two.

 

Ya ya, I know He (and I as well) admit to having a bit of fun with it, but that was only on pavement while it was already rolling... didn't want to stress the new clutch too much during breakin! It's got 31" tires and is 2wd, and never sees serious off road.

I think the pinion gear play was all good. I never actually touched the pinion nut. It stayed on. I had the backlash set for 0.012 I believe.


Thanks for the technical input ND. Much appreciated! I believe this kit would do me then More Information for USA STANDARD GEAR ZIKF9S282.

Now, the thing is whether to do this myself, or to pay a shop to do it. I got quoted 2-2.5 hrs labor, so that's about $200 plus parts. I don't have a problem figuring it out on my own, but I want to be sure its done right.

For the spider/axle gears, do I need to unbolt the carrier, thus causing me to reset backlash? I know I saw on a Dana axle that there is just a split pin that pops out and then the spider gears come out of the carrier.

 

IMO, you should replace the differential and spider gears, all the differential and pinion bearings and cups, pinion shaft, O-ring, pinion and axle seals.

Look at the condition of the ring and pinion, replace if worn.

 

I have a complete 31 spline carrier with spider gears and 3.50 ring and pinion if you're interested. It's all in good condition and was only pulled so I could install a Detroit and 4.11 gears.


only downside is shipping to Canada....that might be a little pricey.


make me an offer if interested. they're just sitting in my garage.

 

Ok, thanks for the advice. Just want to clarify on the reasoning; is it one of those "who knows when they were replaced last, and they might go sometime" or is it more that they might have been damaged by metal shards when the axle/spider gears sheared? Just wondering because that doubles my repair cost, and this is more of a hobby truck for a university student (me!) on a tighter budget. I'm not opposed to doing it right the first time, but just want to make sure its money well spent.

As far as ring and pinion, they still look real good.

Thanks for the offer! unfortunately, I've got 28 spline axles, so I'd have to get into a whole other mess of figuring out axles and bearings and such, so I think I shall pass.

Jeremy

 

Your best bet may be to find a complete "good used" 3'rd member. I have gone that route twice and it worked out OK. Good chance there may be one locally for not a lot of money.

Personally, I will go into the guts of an engine but don't really want to work on a 3'rd member. Also, parts that wear together, especially gears, like to stay together. Mix and match used parts can lead to unpredictable results.