Should I buy this 8 3/4 sure grip center chunk?

Posted By: plazomat

Should I buy this 8 3/4 sure grip center chunk? - 11/11/14 04:22 AM

I can get this locally for about $300 - not sure if its worth the buy?

489 case with 2.89 gears open diff + a used sure grip unit 3.23 with a few broken teeth...see pic please..

Seller says the SG is good, he got it with other parts...how can I tell?

Or cause the teeth broke just run away...

Plaz

Posted By: NTOLERANCE

Re: Should I buy this 8 3/4 sure grip center chunk? - 11/11/14 04:26 AM

I don't see a pic. Does the s/g have clutches?

Posted By: plazomat

Re: Should I buy this 8 3/4 sure grip center chunk? - 11/11/14 04:31 AM

Second try..

Attached picture 8327714-centerchunk.JPG

Posted By: NTOLERANCE

Re: Should I buy this 8 3/4 sure grip center chunk? - 11/11/14 04:41 AM

I would say no

That's a cone type sure grip and while it's not a bad unit it's not rebuild able Well it sorta is. To have to do some machining and it's good to go again. For awhile.

Unless you need the other items id pass. The ratios are poor and one is broken so it makes me question the condition of the s/g.

Posted By: plazomat

Re: Should I buy this 8 3/4 sure grip center chunk? - 11/11/14 04:44 AM

Thanks for the help...I'll pass.

Plaz

Posted By: Kern Dog

Re: Should I buy this 8 3/4 sure grip center chunk? - 11/11/14 04:44 AM

UNLESS you can do a tension test to asses the integrity of the differential, you have to play it safe and assume that the CONE diff is worn out. I'd never buy a used cone diff without a test.
My axle guy puts the diff in a vise and locks one axle down, then tries to spin the other axle with a torque wrench. If the unit slips at anything under 80 ft/lbs, the unit is on its way out.
CONE differentials can be rebuilt but there are some drawbacks to that. It is because of this that even the factory suggested total replacement in the event of excessive wear.

Posted By: NTOLERANCE

Re: Should I buy this 8 3/4 sure grip center chunk? - 11/11/14 04:47 AM

Can't you buy a new sure grip for $400 or so?

Posted By: Pacnorthcuda

Re: Should I buy this 8 3/4 sure grip center chunk? - 11/11/14 04:51 AM

Quote:

Can't you buy a new sure grip for $400 or so?

They've been on back order for over a year...don't know why, Doc Diff would know.

Posted By: DoctorDiff

Re: Should I buy this 8 3/4 sure grip center chunk? - 11/11/14 04:59 AM

New 8.75" (power-lock) clutch internals are available, but the carriers are not. I'm currently having my own carriers made by a different manufacturer.

Complete units should be available by spring.

Posted By: 70blackfish

Re: Should I buy this 8 3/4 sure grip center chunk? - 11/11/14 07:47 AM

I agree with above, don't buy it.

Posted By: bigblock340power

Re: Should I buy this 8 3/4 sure grip center chunk? - 11/11/14 03:42 PM

I would take this guys advise. Watch towards the end of the vid. around 3.35 on. That's what I'd do!
http://www.youtube.com/watch?v=ZfL4xKQeSfo

Posted By: jcc

Re: Should I buy this 8 3/4 sure grip center chunk? - 11/11/14 10:53 PM

If its a 2.89, yes, its one of one

18/52 R/P tooth count?

Otherwise, No, plenty of other bigger fish in the pond.

Posted By: plazomat

Re: Should I buy this 8 3/4 sure grip center chunk? - 11/11/14 11:41 PM

Quote:

If its a 2.89, yes, its one of one

Oh man how many of you caught that one and didn't call me out.....

Plaz

Posted By: GTX MATT

Re: Should I buy this 8 3/4 sure grip center chunk? - 11/12/14 01:17 AM

Not worth 300, I'd say the SG unit it worth 100. Value the rest at what you want.

Posted By: JohnRR

Re: Should I buy this 8 3/4 sure grip center chunk? - 11/12/14 04:38 AM

Quote:

Not worth 300, I'd say the SG unit it worth 100. Value the rest at what you want.

the sure grip may be worth $100 but only if it's not junk ... but it's a cone type so it's already JUNK by design.

Posted By: NTOLERANCE

Re: Should I buy this 8 3/4 sure grip center chunk? - 11/12/14 06:41 AM

Quote:

Quote:

Not worth 300, I'd say the SG unit it worth 100. Value the rest at what you want.

the sure grip may be worth $100 but only if it's not junk ... but it's a cone type so it's already JUNK by design.

Haven't you read all these posts about cone types surviving 600 hp for years?

I agree. Junk. The powr loc designed clutch type is the way to go for performance
That being said for a driver stock engine car. Eh doesn't matter I guess

Posted By: Jjs72D

Re: Should I buy this 8 3/4 sure grip center chunk? - 11/12/14 09:40 AM

A cone unit is better than nothing if you can get it cheap.

Posted By: feets

Re: Should I buy this 8 3/4 sure grip center chunk? - 11/12/14 04:13 PM

Quote:

Haven't you read all these posts about cone types surviving 600 hp for years?

The cone type survived for 12 years behind the TT440 with manual and automatic transmissions.

It was still locking up and making traction in the end despite the locking screw for the cross pin breaking. When that happened the pin spun in the case and ate the diff. However, the cones were still holding the axles together.

I ended up replacing it with a TrueTrac.

Posted By: JohnRR

Re: Should I buy this 8 3/4 sure grip center chunk? - 11/12/14 07:52 PM

Quote:

It was still locking up and making traction in the end despite the locking screw for the cross pin breaking. When that happened the pin spun in the case and ate the diff. However, the cones were still holding the axles together.

That happened because the spiders on that shaft had welded them selves to the shaft, it wasn't in as good a shape as you think ... but at least you had fun ...

Posted By: feets

Re: Should I buy this 8 3/4 sure grip center chunk? - 11/12/14 11:03 PM

Quote:

Quote:

It was still locking up and making traction in the end despite the locking screw for the cross pin breaking. When that happened the pin spun in the case and ate the diff. However, the cones were still holding the axles together.

That happened because the spiders on that shaft had welded them selves to the shaft, it wasn't in as good a shape as you think ... but at least you had fun ...

Yep. One was stuck pretty good but the other was free. Still, the cones were working as designed.