Welded Spider Gear Quiestions

[ThomasE30]

The 85' 325e I'm buying has a welded differential and I was wondering what my options are as far as removing it. The guy said it is just the spider gears that are welded together and I don't know much about diffs but I think I can just replace those with another pair. If it isn't just the spider gears that are welded and I would have to replace the whole diff, does anyone have any suggestions for which kind and ratio to get? I've seen people mainly like the IS diffs and that seems like something I'd like to have instead of an open diff. The diff is actually surprisingly not as bad as i thought it was gonna be because he did say it is a strong weld but it's just not something I'd like to have. Lastly, I cannot seem to find anyone that makes spider gears that you can buy so would I have to find a junker or part out that wouldn't mind just doing the spider gears or a diff entirely? Any help and information is appreciated.

[sampayne]

It would be easier to find a complete diff and just swap it over. Also a good time to do new seals before its installed. Open diffs are cheap and bountiful. Lsd's aren't too hard to find either, just cost more $$$.

[ThomasE30]

It would be easier to find a complete diff and just swap it over. Also a good time to do new seals before its installed. Open diffs are cheap and bountiful. Lsd's aren't too hard to find either, just cost more $$$.

Okay thanks for the reply. I figured I was just gonna have to get a new diff since I can't buy just spider gears anywhere like ECS. Thank you. I'm gonna try to find an LSD but and open diff would be fine if i can't. Do you recommend any specific gear ratios?

[TobyB]

For an eta, the factory thought a 2.93 or even a 2.7 was a good idea.

But that's an awfully tall first and third gear- if you want more zip, something a bit shorter
makes sense. Honestly, drive what's in there just for ratio, then see where you want to go.

Because some people don't mind slipping the clutch and a slow launch, while others
don't mind buzzing along at 4k on the freeway. In an eta, though, a 3.73 or taller
will run you out of the power band before you're over the speed limit enough to lose your license...

And yes, grabbing the spider gears out of a donor diff is fine, IF they weren't welded to the carrier.
It's kinda tricky to NOT weld to the carrier or the cross AND weld them nice and solid.

t

[ThomasE30]

For an eta, the factory thought a 2.93 or even a 2.7 was a good idea.

But that's an awfully tall first and third gear- if you want more zip, something a bit shorter
makes sense. Honestly, drive what's in there just for ratio, then see where you want to go.

Because some people don't mind slipping the clutch and a slow launch, while others
don't mind buzzing along at 4k on the freeway. In an eta, though, a 3.73 or taller
will run you out of the power band before you're over the speed limit enough to lose your license...

And yes, grabbing the spider gears out of a donor diff is fine, IF they weren't welded to the carrier.
It's kinda tricky to NOT weld to the carrier or the cross AND weld them nice and solid.

t

Okay thank you for your suggestion. I do like how the car is now so just getting what it has now doesn't sound bad. I'll have a look to see if the spider gears are welded to carrier or not but I think just getting another diff around here will be easier.