My Dif Pin

[NBSHO]

My Tranny woes....

Well,

I just spent almost $2400 to get my tranny rebuilt. The planetary grenaded... the tranny shop said the pump in it was bad as well. I got basically a new trans in the old case...lol The guy who took it in and out said it was not the easiest tranny to get in and out....but now it's fixed and runs MUCH better...the funny thing is now my temp guage is workin properly again

 

[TYSHO]

I've never seen a ring gear from Autozone and because of that I can't say they are good or not. But at 40.00.......I'd be worried. I would have to get one and compare it before I give it my stamp of approval. If you have a part number please supply it.

Sorry for the misunderstanding...I was talking about the flywheel ring gear! Although, it would be nice to have an ability to buy one.


BTW if I can ever get some pics up, I will show you what I did to my diff. I changed it up even better!

 

[pjtoledo]

Just ah FYI...you can always buy a new ring gear from AutoZone for $39.99 besides hassling with the rivets. That's if you go with the Quaife though.

IMO, if you believe the inner opening of any internal differential gears are worn...I would leave it like that and replace the shafts only, if worn, because if you replace the spider gears it'll have more friction, as both are new, non-worn. The gears inside pretty much hold theirselves in shape, like a cube. The shafts just keep them from free spinning in the inside, which would make the differential useless.

Not sure I understand you here. Are you saying that a new spider gear with a polished bearing surface on the inside riding on a new polished dif pin will have more friction than an old spider gear with a chewed up inner surface riding on a new polished (but not for long) dif pin?

Lets not forget that even when the spiders gears are not spinning on the pins, ALL the torque that moves the vehicle is manifested as a side load on the spider gears and dif pins.

Perry

 

[TYSHO]

Not sure I understand you here. Are you saying that a new spider gear with a polished bearing surface on the inside riding on a new polished dif pin will have more friction than an old spider gear with a chewed up inner surface riding on a new polished (but not for long) dif pin?

Perry

Let's see...more contact area = more friction!

Okay, you have a new shaft with a worn spider gear riding on it, larger diameter inner surface area that's worn, not chewed. While the differential is moving the shaft and spider gear are applying equal forces. While doing so, the spider gear remains still until it sees some turning. As that happens, both are still applying equal forces as the spider gear is now riding around the shaft, with a larger diameter. Therefor, the shaft is only seeing like 1/3-1/2 of it's surface area in contact with the spider gears inner opening. With a gap between the two, it would allow more fluid between. As for the new gear, it would have 100% contact, assuming it's a tight fit. If not, it's more than 50%. That's why I believe none have broken, because friction build up is less and the max damage has already took place. Although, my theory on damage can be wrong, but I have yet to hear of a shaft break, completely, in half.

 

[AutoSHO]

If you have a worn spider gear, then it is going to contact less of the surface, thus putting an incredibly high load on the one or two small points that are touching... This will cause the Pinion shaft to gall/wear almost immediately, negating all the work you just did. Also, with the larger tolerance of the worn spider gears, they will be more apt to bind on the shaft due to excess play. If you're going to the trouble of rebuilding the stock differential, replace the gears, shafts, and the bearings between the spider gears and diff housing.

 

[TYSHO]

Honestly, I don't think the spider gear inner opening will even wear. It's a stronger metal than the shaft, correct? And what we're talking about is something we'll probaly "never" experience. This is a "very" rare case to happen. Can you list 10 people this has happened to?

BTW how can two smooth surfaces wear faster on less area than one with more? Like I said, worn, not chewed. And both loads, regardless of which parts are replaced, are in the same area. The new parts are not going to evenly distribute load around the whole shaft! It's just a matter of more contact area.

 

[pjtoledo]

Honestly, I don't think the spider gear inner opening will even wear. It's a stronger metal than the shaft, correct? And what we're talking about is something we'll probaly "never" experience. This is a "very" rare case to happen. Can you list 10 people this has happened to?

BTW how can two smooth surfaces wear faster on less area than one with more? Like I said, worn, not chewed. And both loads, regardless of which parts are replaced, are in the same area. The new parts are not going to evenly distribute load around the whole shaft! It's just a matter of more contact area.

I just took another look at the spider gears from an ejected dif pin tranny. All four are galled, one lightly, the others badly. In addition one of the bearing plates that go between the spider gears and the diff housing was completely cracked on one side, 90% cracked on the other side. That means the tranny was about to have 2 pieces of a steel free floating around in with the spider gears. Another reason to replace the spiders.

The bit about less area means less friction does not apply here. That theory works fine about reducing the overall bearing area of crank journals spinning at hi speed under full power. Keep in mind that those bearings are still matched to the curvature of the crank,,they fit right.
You are proposing that 2 surfaces of different radius be mated, that will result in an extremely small contact area. With all the load concentrated on such a small area wear will be accelerated. Couple that with the worn inner surface and the old gears will chew up the new pins even faster.

Perry