Hot Racing Diff Cup

[Priortothis]

So I picked up a hot racing aluminum diff cup for my center diff because I run in gravel a lot and will also be going with 500k oil and want to try and prevent leaking. I got it today and put it together and when I went to put the screws in I noticed all 4 screw holes were full of diff oil, so I cleaned it out and thought what the heck, I probably sent some in there while I was putting it in. I let it sit for another few minutes to wait for another bubble to surface and I noticed the screw holes were full again. I’d prefer not to waste my fresh diff oil but looks like i will need to clean it to investigate/return for a new one. Anyone else have this issue?

 

[2fast4u]

It should only be filled to where it's just covering the cross pins. If you fill it clear up it will over flow when you put the other half on it.

 

[Priortothis]

It should only be filled to where it's just covering the cross pins. If you fill it clear up it will over flow when you put the other half on it.

I understand that, the screw holes were full before I tried to put the spur on, I put the oil in the gears and was waiting for it to settle and somehow via a pin hole or otherwise it was filling into the screw holes

 

[Priortothis]

So I cleaned it up and found that there’s slots that are open from the main cavity to each screw cavity? Can anyone confirm this is normal?

 

[Rrr184]

Yeah, same on mine...

 

[bicketybam]

Don't waste your time emailing them. They don't respond to emails.

 

[Notorious J]

So I cleaned it up and found that there’s slots that are open from the main cavity to each screw cavity? Can anyone confirm this is normal?

I already installed one, and never looked, but I did notice that fluid was in the hole before I put it together. I use old rivet shafts to line up the spur and ring gear when I put my difs back together. I like the way it helps to line everything up. As I removed each one to add a screw, there was dif fluid on all four. This must be part of the design, although I don't know how it benefits anything. I still have one new cup waiting to be used, so I'll have a closer look when I get home today.

 

[2fast4u]

That slot is most likely there to prevent having oil trapped in the bore below a screw that would prevent proper tightening. Liquids are not compressible and heavier ones would not escape up through the threads. Yes it let's it in, but it let's it escape. Which would not happen with a blind hole. Another benefit would be that the presence of oil on the threads will slow electrolysis between the dissimilar metals (steel screw/aluminum cup). Preventing the related corrosion from destroying the threads and/or making the screw impossible or nearly impossible to remove.

 

[3dplank]

How do you loctite these bolts? If it is filled with oil?

 

[Notorious J]

How do you loctite these bolts? If it is filled with oil?

I don't.

 

[Notorious J]

That slot is most likely there to prevent having oil trapped in the bore below a screw that would prevent proper tightening. Liquids are not compressible and heavier ones would not escape up through the threads. Yes it let's it in, but it let's it escape. Which would not happen with a blind hole. Another benefit would be that the presence of oil on the threads will slow electrolysis between the dissimilar metals (steel screw/aluminum cup). Preventing the related corrosion from destroying the threads and/or making the screw impossible or nearly impossible to remove.

What ^ said

 

[3dplank]

I thought all metal to metal used loctite. They wont vibrate out?

 

[2fast4u]

I thought all metal to metal used loctite. They wont vibrate out?

Most likely not if properly tightened. You should also soak the paper gasket in some thinner shock oil overnight. Wipe it off, then install. This will swell the fiber's and let it conform to the surface better. Also aids with letting it shift easier during the tightening process.

 

[olds97_lss]

Yeah... that's retarded. I've had many alloy diff cups come loose, even with lock tite. If it were me, I would have roughed it up with sand paper and put a bit of JB weld in there from the cup side to plug the hole before silicone oil was put in. But now that you have oil in there, will be hard getting it out of the bottom of the hole so anything can adhere.

If those slots didn't exist, there really isn't any reason oil would get in the screw holes unless you improperly overfilled the diff. I've had many brands of diffs over the years and never saw one like that.

 

[3dplank]

I agree. We assemble many parts where I work. No loctite on this part would not fly. It will eventually loosen up. I think I will stay away from this upgrade.

 

[Priortothis]

I don't.

How long have you been running it? Have you checked the screws? I already have the cup so if it doesn’t seem to be an issue without loctite then I may just install anyways and see how it goes

 

[Notorious J]

How long have you been running it? Have you checked the screws? I already have the cup so if it doesn’t seem to be an issue without loctite then I may just install anyways and see how it goes

I haven't yet. I installed the new dif on Thursday, so I'll keep an eye on it. If it means a quick check of the screws after each run, no big deal. I'll update after three or four packs.

 

[Walküre]

I’ve ran nearly 100 packs of 4-6s through my car rithout any loose screws. The plastic ones have a grub screw to let out extra oil and air when assembling. These don’t. The air oil must escape somewhere or the diff won’t fully seal. I have them on all 3 of my Typhon diffs. I tighten 3 screws, wipe away the oil and install the last with loctite. Remove the others and loctite all around, gorilla tighten them and done. Never had an issue with them even with oil loctite mixing.

 

[PowerDubs]

Yup- just put 2 of these together over the weekend. Put screws in each hole and removed- all 8 screws had a wet tip from oil in the hole.

 

[joostin420]

I have built quite a few of these. I do not put any fluid in before hand and just add to the top of the planetary gears once installed. I do rotate the gears and push the fluid in a few times with a toothpick. it has been 30k, 60k, 100k, 200k or 500k and it is so thick i have not noticed fluid in the screw holes. Now after running on the other hand there will be thinned fluid in the holes.