[sdbob]

Wanting to buy new posi. Looking at list 557 is a 28 spline,the 559 is 30 spline but lists 8.5/8.6".Will 30 spline work in stk 8.5 housing? Buying new Moser axles and probably 4.10 gear for the 455.Had 4.56s in it first just thought to much gear.

[BruceWilkie]

Haven't got a clue on your 10 bolt questions .
Having gone from 4.10 to 4.56 ...hind sight says I should have tried 4.30' s. 4.56 was too much unless I went taller tires which was another possibility.

[sdbob]

Only 4.33s that I've seen were for 12 bolt.Moser has them as an assembled rear,didn't see them on Summits sight . Thanks

['ol Pinion head]

Originally Posted by sdbob

Wanting to buy new posi. Looking at list 557 is a 28 spline,the 559 is 30 spline but lists 8.5/8.6".Will 30 spline work in stk 8.5 housing? Buying new Moser axles and probably 4.10 gear for the 455.Had 4.56s in it first just thought to much gear.

Have upgraded many early 8.5 A-body & F-body rears over the last 20 years to 8.5 30 spline Eaton carriers & Moser axles. In order to use the 30 spline style carrier in the pre '88 8.5 housing, will need to buy a pair of LM 102949 carrier bearings & pair of LM 102911 carrier bearing races.

[Skip Fix]

My 81 , and soon the 78 , has an Eaton 30 spline posi. Axles need to be 10 bolt specific as the C clip button is not as thick as a 12 bolt.

[jonmachota78]

Originally Posted by Skip Fix

My 81 , and soon the 78 , has an Eaton 30 spline posi. Axles need to be 10 bolt specific as the C clip button is not as thick as a 12 bolt.

Yup. However you can shave the button down on 12 bolt axles to work in the 10 bolt housing. Mine has been working fine. 30 spline eaton, KA axles. 1/2" bolts and steel carrier bearing cap on the ring side.

[sdbob]

Thank you guys I know someone has done it.

[Skip Fix]

If you are going aftermarket axles-which 30 spline you probably will need to and using rear discs and a hubcentric wheel you will need a longer brake pilot on the axle-Dutchman is the only one to offer that.

And Tom's Differentials usually has a killer price on the carrier.

[highway star]

I recently installed the Eaton Posi, Richmond R&P gears & Moser Street Axles in my '94 C1500
Silverado. Lays 2 even length black marks. Also, Richmond has great install
kits with Timken bearings & necessary components. Got it all at Summit Racing.

[sdbob]

Thanks.

[ta man]

How much power can the 30 spline carrier/axle swap handle?

[Skip Fix]

Well the stock 28 spline 4WD axles and an Eaton 28 spline has been handling mine for years even with low 1.5s when I had the 5000 stall convertor.

I think Moser has a spot on their site about gear ratio and axle spline TQ capacity.

[ta man]

Originally Posted by Skip Fix

Well the stock 28 spline 4WD axles and an Eaton 28 spline has been handling mine for years even with low 1.5s when I had the 5000 stall convertor.

I think Moser has a spot on their site about gear ratio and axle spline TQ capacity.

Thanks Skip..I haven't grenaded the stock 8.5 yet.It definitely needs done before spring.I didn't expect this heavy car with the mild gear and convertor to get into the 1.56 range parts are going to start breaking.Time for the 30 spline Eaton and a set of Dutchman axles..

[Skip Fix]

Tom at Tom's Differentials years ago told me the stock posi will grenade before the stock axles do. If you need more than 30 spline there are 33 spline spools for 8.5s.

Your 60 fts are really great my best with a bigger cammed 455 and 5000 and 4.10s was only a 1.51.

Sometimes combinations fool you. I pulled that motor out and put in the current 296/304 HFT 455 and a Hand convertor in my car to tone it down. Maiden track test was in some really good fall air and it clicked off almost as fast a 1/4 mile, 60 fts way less but a 10.99@124!

[TCSGTO]

Mosers' axle formula
Torque at axle=Peak engine torque x first gear ratio x rear gear ratio x .90

30 spline Moser axle is rated at 6200 ft-lb
31 spline 7000 ft-lb
33 spline 8200 ft-lb
35 spline 9600 ft-lb

As long as your axle torque is under these numbers your ok according to Moser.

[ta man]

Originally Posted by Skip Fix

Tom at Tom's Differentials years ago told me the stock posi will grenade before the stock axles do. If you need more than 30 spline there are 33 spline spools for 8.5s.

Your 60 fts are really great my best with a bigger cammed 455 and 5000 and 4.10s was only a 1.51.

Sometimes combinations fool you. I pulled that motor out and put in the current 296/304 HFT 455 and a Hand convertor in my car to tone it down. Maiden track test was in some really good fall air and it clicked off almost as fast a 1/4 mile, 60 fts way less but a 10.99@124!

I never expected the 1.56's!

[Skip Fix]

Even looking at Moser's formula you see engine TQ is multiplied times gear ratios-so how can a chassis dyno compare even the same motor with different rear or tranny gears??

[PersonX51]

8.5 10 bolt can be quit strong if setup correctly. I would recommend after market axles and C-Clip eliminators Moser make a nice set of 33 spline axles that come with C-clip elims. and a spool and Mark Williams makes a 35 spline setup with C-clip elims. and a spool. Also so the reinforced cover with the bearing support is a great idea.

Links
http://www.moserengineering.com/spoo...ator-type.html

http://www.markwilliams.com/detail.aspx?ID=1883

The Moser setup is cheaper but of good quality.. I know .. I run that setup in my 78 Bird.
IMO if your going to be racing .. just put a damn spool with C-Clip elims. in .. is having the posi really worth the crash if you snap and axle?

[TCSGTO]

Originally Posted by Skip Fix

Even looking at Moser's formula you see engine TQ is multiplied times gear ratios-so how can a chassis dyno compare even the same motor with different rear or tranny gears??

They can't.

[Skip Fix]

Originally Posted by TCSGTO

They can't.

Need to tell that to the "dyno queen" LS guys!