unitized bearings on d30

I kind of destroyed my bearings on the front end trying to get it out and was wondering, do I have to replace the whole unit at $150 a pop?

Yup.




There are cheaper ones out there than $150 though - I seem to recall in the area of $85-100 or so.

Jim www.yuccaman.com

look into swapping to a 84-89 roller bearing unit. Theres a reason why everyone blows through the late model ball bearing design.

I think the newer models use a needle type bearing instead of the ball type.

My 87 Bearings are OE from 87 and holding up nicely. Although mine is bone stock.....

I was under the impression the 90 & later unit bearing was an improved design. I always figured I would upgrade my 87 to the later type if they ever fail. I even saved spare pair of later hubs from one of my projects in case I ever need them.

poorboy_616 said:

I think the newer models use a needle type bearing instead of the ball type.

My 87 Bearings are OE from 87 and holding up nicely. Although mine is bone stock.....

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Nope. 90+ are ball bearing with a torsion race design. Even though it's better than a typical ball bearing race it simply can't handle high thrust loading (typical of big tire Jeeps). This type of load is really suited for a tapered roller bearing.

Ball bearings are great for linear loads and high RPM, but HORRIBLE for any thrust loading. Hence why they are used in transmissions for example.

I'm not surprised you havn't had an issue with your 87.

was under the impression the 90 & later unit bearing was an improved design. I always figured I would upgrade my 87 to the later type if they ever fail. I even saved spare pair of later hubs from one of my projects in case I ever need them.

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Definetly not. I'd really like to know why they did swap the design, but I'd be willing to bet it's related to cost. Jeep is actually the only MFG that I know of that chose to use a ball bearing style wheel bearing (stupid). :banghead:

Thank you gentlemen. I appreciate it.
Darin

Bryson said:

Nope. 90+ are ball bearing with a torsion race design. Even though it's better than a typical ball bearing race it simply can't handle high thrust loading (typical of big tire Jeeps). This type of load is really suited for a tapered roller bearing.

Ball bearings are great for linear loads and high RPM, but HORRIBLE for any thrust loading. Hence why they are used in transmissions for example.

I'm not surprised you havn't had an issue with your 87.

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I don't have a lift or bigger tires as of yet. I guess I will see when the lift and tires go on next year!

I've had 31"s & a lift on my 87 for years, maybe 100k, & 260k on the original hubs with no problems.When the unit bearings go it'll be time to buy locking hubs. I've repeatedly been told the later hubs are better but I guess Mopar strikes again. No wonder I love my AMC Renix.

cherokee chuck said:

I've had 31"s & a lift on my 87 for years, maybe 100k, & 260k on the original hubs with no problems.When the unit bearings go it'll be time to buy locking hubs. I've repeatedly been told the later hubs are better but I guess Mopar strikes again. No wonder I love my AMC Renix.

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Yup. I had to replace my 99 units with only 90k on the clock. Unfortunetly I learned only after I replaced them about the ball bearing design.

The only difference is that they require the matching brake rotor because of a slightly different caliper offset between styles.

You can get Timken unit bearings for $75 each from rockauto.com.

They last MUCH longer than anything else out there, I put 50k on my last set on 35's before giving them to someone else who's put another 50k on them on 32's, and they are still tight.