how cheap can you do a 9" alum 3rd member? $900?
11-30-2017, 08:10 PM
#1
how cheap can you do a 9" alum 3rd member? $900?
a few months back I did a few 9" ford aluminum 3rd members.. I had so many left over parts I put them up for sale....no takers..so last week thanks giving sales going on all over the place..I picked up a another aluminum 3rd member to put together... it came with the Daytona support (10 bolt) face.. for $245 sale shipped.. ordered the 1350 billet yoke and pinon support bearing.. ARP pinon nut.$112 sale. this is also a H case Locker with 3.25 bearings..31 spine..when done..
this should come in at just under $600 when done...we will see..
this should come in at just under $600 when done...we will see.. Last edited by articwhiteZ; 03-03-2018 at 04:09 PM.
12-01-2017, 12:52 PM
#2
12-30-2017, 11:24 AM
#6
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Car: 87 IROC L98
Engine: 588 Alcohol BBC
Transmission: Powerglide
Axle/Gears: Ford 9"/31 spline spool/4.86
Re: how cheap can you do a 9" alum 3rd member?
How much power to 31 spine axles depends on how much torque you're producing. I use a 1.76 powerglide so my first gear torque multiplication isn't as high as someone using a 3-4 speed transmission.
engine torque x first gear ratio x diff gear ratio x 0.9 (driveline loss) = torque to the axles.
Moser used to have an axle chart but it's long gone. They want each axle to handle the maximum amount of torque produced which means with 2 axles, each really receives half that amount as a safety margin.
30 spline = 6200 pounds per axle
31 spline = 7000
33 spline = 8200
35 spline = 9600
40 spline = 12,000
I've never dynoed my car but I'll make a wild guess of 800 pounds of torque.
800 x 1.76 x 4.86 x 0.9 = 6158.6 pounds of torque. Using the above chart, I'm still under the 31 spline limits. A relatively simple upgrade is to go to 31 spline axles. Going to 35 spline would mean I would need a different center section with larger side bearings.
Now lets say I decided to get rid of the powerglide and go with a TH400. The first gear is lower.
800 x 2.48 x 4.86 x 0.9 = 8678 pounds of torque. I would then need to jump over 33 splines and go directly to 35 spline axles.
When I bought my Moser 31 spline axles, the first thing I did was paint a white line down the axle before installing them. Years later when I had to pull my axles, the line was still straight and the splines were still straight meaning there hasn't been any twisting done.
Moser aluminum bolt through center section. Aluminum Daytona pinion support. Solid crush sleeve. Aluminum spool. 4.86 gears. I can lift the diff in with one hand.
engine torque x first gear ratio x diff gear ratio x 0.9 (driveline loss) = torque to the axles.
Moser used to have an axle chart but it's long gone. They want each axle to handle the maximum amount of torque produced which means with 2 axles, each really receives half that amount as a safety margin.
30 spline = 6200 pounds per axle
31 spline = 7000
33 spline = 8200
35 spline = 9600
40 spline = 12,000
I've never dynoed my car but I'll make a wild guess of 800 pounds of torque.
800 x 1.76 x 4.86 x 0.9 = 6158.6 pounds of torque. Using the above chart, I'm still under the 31 spline limits. A relatively simple upgrade is to go to 31 spline axles. Going to 35 spline would mean I would need a different center section with larger side bearings.
Now lets say I decided to get rid of the powerglide and go with a TH400. The first gear is lower.
800 x 2.48 x 4.86 x 0.9 = 8678 pounds of torque. I would then need to jump over 33 splines and go directly to 35 spline axles.
When I bought my Moser 31 spline axles, the first thing I did was paint a white line down the axle before installing them. Years later when I had to pull my axles, the line was still straight and the splines were still straight meaning there hasn't been any twisting done.
Moser aluminum bolt through center section. Aluminum Daytona pinion support. Solid crush sleeve. Aluminum spool. 4.86 gears. I can lift the diff in with one hand.
12-30-2017, 01:39 PM
#7
Re: how cheap can you do a 9" alum 3rd member?
no.. just units on hand for tuning.. and fun...or back up parts.. the black one is not in the pic..but I have 3 for my car at this time..
all units are aluminum.31 spline lockers. Solid crush sleeve with 1350 billet yokes.ARP pinon nut.and studs.
4.11 bare aluminum pinon support
4.30 (black) support
4.56 red support
might do one with 3.90 gears..the 3rd unit I did for under $600..with black Friday sales and left over parts..
this is the black unit (color of the pinon support) not put together as of yet..all parts on hand in a box..lol (4.30 gears)
all the units are rated for 1200hp..going to test that!
I have looked at solid billet housing..but at a cost of $2400 for just the housing..is crazy..
but if I back half the car...then yes ill spend the money for the billet housing...
Last edited by articwhiteZ; 12-30-2017 at 03:08 PM.
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03-03-2018, 03:08 PM
#10
Re: how cheap can you do a 9" alum 3rd member?
how you start one on the cheap..when done you have a total under $900 even with an aluminum housing..(shop around)
https://www.ebay.com/itm/Ford-9-Detr...5Xfnhr&vxp=mtr
when you pick out a aluminum housing..pay attention to the pinon support bolt size..they make 2 diff ones on the market.in my pics you can see.. 2 diff stud sizes..i like the 1 stud size for all 10 pinon studs..(just me)ARP ss studs $38 a set of 5..you need 2 sets..the Yukon units come with the studs as all units do..i just like the bling of the SS arp studs..
the Yukon units also don't have a dual oil feed for the pinon bearings..just the one hole (I like the dual oil holes) more flow to the pinon bearings..(just me)...also when you buy your pinon yoke..(1350) get a good billet unit..yes you can spend $75 to $125 on a yoke..but it will last a life time without fail! (I have a billet nascar) 1350 unit for sale at this time $70 shipped! they are a work of art...
this shot ya can just see 1 of the dual feed holes in the pinon support (in the dark shadows)
https://www.ebay.com/itm/Ford-9-Detr...5Xfnhr&vxp=mtr
when you pick out a aluminum housing..pay attention to the pinon support bolt size..they make 2 diff ones on the market.in my pics you can see.. 2 diff stud sizes..i like the 1 stud size for all 10 pinon studs..(just me)ARP ss studs $38 a set of 5..you need 2 sets..the Yukon units come with the studs as all units do..i just like the bling of the SS arp studs..
the Yukon units also don't have a dual oil feed for the pinon bearings..just the one hole (I like the dual oil holes) more flow to the pinon bearings..(just me)...also when you buy your pinon yoke..(1350) get a good billet unit..yes you can spend $75 to $125 on a yoke..but it will last a life time without fail! (I have a billet nascar) 1350 unit for sale at this time $70 shipped! they are a work of art...
this shot ya can just see 1 of the dual feed holes in the pinon support (in the dark shadows)
Last edited by articwhiteZ; 03-03-2018 at 03:39 PM.
03-03-2018, 03:38 PM
#11
Re: how cheap can you do a 9" alum 3rd member?
this pic shows a billet pinon 1350 yoke sitting next to a long cast yoke... get the strong billet..last a life time.. they also make the biilet yokes in the long type..I switched over to the sort type..as I wanted a stronger set up...(just me) you can also see the biilet Chrome Molly is going to drop some Weight.(size matters)that's the point of going to a aluminum housing.
the above parts run under $400..(ya need to shop) it can be done..(I did it 3 times..its easy)
the above parts run under $400..(ya need to shop) it can be done..(I did it 3 times..its easy)
Last edited by articwhiteZ; 03-03-2018 at 04:13 PM.