How complex is it to machine QT cones? Any specs on alloys?

[Nikkormat]

I was thinking recently about how much I love quadratrac and began to worry what I would do when mine needs service and I could no longer perform it due to a lack of parts. Well now I've found myself a spare to pull but how long will those parts last? I'm hoping that the new chains don't fall through and those alloy USA ones look really nice but what about other wear parts?

Then it dawned on me that I have access to a machine shop rivaling most in the country and skilled technicians to run that shop for damn near free. I just have to pay back material costs and sweat equity. So what if I tried to make some parts?

Do you think some cones could be CNC lathe cut?
Are there any wear parts that could be made on a five axis mill?
What kind of alloys would be required to produce some cones?
Would anyone trial them for me? And after that would anyone else buy them?


This may be a bad idea, but unless its simply impossible I would still like to try. So please remain constructive. I already know that I am insane for trying.

[Stuka]

This is a brake cone and where it goes inside the diff:



They could of course be made, the problem has been cost vs demand. I am not sure of the alloy, I am sure it is some sort of hardened steal. Not sure if that information is even available anywhere.

Most QTs out there have bad brake cones though, which basically turns the center differential into an open differential. I have driven one where when you stepped on the gas hard it would spin a front tire because the cones would not grab enough to send power to the rear.

[fulsizjeep]

The part that has the inner spline and outer grooves is actually called the brake cone. The cone washers (aka: belleville washers) are another thing - 3 of them at the bottom of picture. There are 2 brake cones and 3 cone washers install on each brake cone with the thrust washers (also shown).

[ghcoe]

From my understanding the cones and differential wear in together from new. Just replacing a cone is a shot in the dark whether it will work right in it's new home or not. To do this right it would be best to make all differential components new and sell as a complete unit.

On the other hand I often wondered if someone could make a drop in new spline section that a machine shop could install to replace the worn out splines on the clutch cone only. That is usually where the failure is anyway. Also some new washers. If this could work it would be nice to have a place setup that you could just send your quadra trac differential in, have it R&R and sent back. Just a though.

[Nikkormat]

The washers are definetly something I can look in to. Plate steel milled to thickness and then cut on a water jet.

As for the cones I think it would be doable but I need to talk to the shop guys about cutting internal splines...

What about a drop in center section with a different style LSD? Maybe using modern easy to find parts? Shoot maybe even just a spartan style locker in there. Hmmm decisions decisions...

[Stuka]

The washers are definetly something I can look in to. Plate steel milled to thickness and then cut on a water jet.

As for the cones I think it would be doable but I need to talk to the shop guys about cutting internal splines...

What about a drop in center section with a different style LSD? Maybe using modern easy to find parts? Shoot maybe even just a spartan style locker in there. Hmmm decisions decisions...

An automatic locker would not be what you want. It would basically be locked all the time, making it just like a part time 4wd. Plus I am not sure of any small enough to fit in there.

I think the washers are hardened steel. I think mild steel would wear rather fast. But making them the right size would be easy.

[FSJ Guy]

Belleville washers are actually sort of like springs. They are angled. Think of a REALLY flat cone with the middle cut out. If you place one on your desk, the inside ridge is higher than the outside ridge, but the cross section is the same thickness on both the inside and outside.

http://en.wikipedia.org/wiki/Belleville_washer

EDIT: And they aren't usually the parts that need replacing.

[fulsizjeep]

EDIT: And they aren't usually the parts that need replacing.

This is pretty true. What I have seen is when there is enough metal debris floating around inside the differential (stripped brake cone spline, heavily worn spider gear/cross shaft, etc.), particles will get ground into the cone washers and scar the hell out of them. I do not reuse them when they are all scarred up.

[KJ Ryu]

EDIT: And they aren't usually the parts that need replacing.

This is pretty true. What I have seen is when there is enough metal debris floating around inside the differential (stripped brake cone spline, heavily worn spider gear/cross shaft, etc.), particles will get ground into the cone washers and scar the hell out of them. I do not reuse them when they are all scarred up.

This is probably out of line but, what would you charge me if I sent you 3 1339s and only wanted one good one in return? I know you know the tolerances/limits better than anyone so I'd be willing to pay a little bit of a premium for premium work. PM me if you don't want to share but, I am very serious.

[KJ Ryu]

Also, if anyone can find blueprints for the cones, I can machine them out of any material you want. 4130, 4140, 4340HT, 4330+V.... you name it. I just need the numbers.

[fulsizjeep]

This is probably out of line but, what would you charge me if I sent you 3 1339s and only wanted one good one in return? I know you know the tolerances/limits better than anyone so I'd be willing to pay a little bit of a premium for premium work. PM me if you don't want to share but, I am very serious.

I have done a couple rebuilds for others. You might want to check on shipping cost to 81328 first. That will be about 300 lbs of QT to ship plus a new chain and seal kit then the return trip.

[KJ Ryu]

I would probably just deliver them, in person. It'd be a few months before I can but, I'm not in a huge rush.

[Nikkormat]

Yeah how much would you charge? I'd love to have a real professional rebuild mine. In person delivery and a cold six pack of your choice included of course.

[Nikkormat]

If I crack open the case Im getting I'll make cad files of what ever you want.

[KJ Ryu]

If I crack open the case Im getting I'll make cad files of what ever you want.

That would work great, as long as you are certain the parts aren't too worn to get true measurements from.

[fulsizjeep]

I have a NOS QT. It needs to be torn down before I can use it. Maybe I can get motivated to do that over winter and have new cone washers to loan for CAD work. Let me think on the rebuild jobs. Probably looking at 4-6 hours work to go through one. All depends on what is good and what is bad. For instance, it would be more economical to build one with a case that has good bearings in it that to buy new ones. I am not sure if there is a reliable source on bearings. I have a set put away that I bought about 10 years ago. It has been that long since I searched.

[fulsizjeep]

If I don't have to supply parts or any pressure washing of the case, I think $250 for the labor would be fair. Owner provides parts like seal kit and chain. Fork pads and vacuum shifters are pretty common wear items as well as the fiber thrust washer on main drive sprocket.

[Nikkormat]

That sounds fair. I'll keep it in mind once I get the new case.

[KJ Ryu]

I'll probably be knocking on your door this summer, Flint. Price seems fair. Hope you don't mind if I hang out and attempt to partake of a little knowledge.

[fulsizjeep]

Sounds good guys. Let me know when you have a plan figured out on your end. Meanwhile, I should get one QT project done that has been on the back burner. Thank You.