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Axle advice needed
#1
Hi, I need a spot of advice on my axle components.

I have been stripping my 9 Inch axle down to get it ready for a change of ratio and new bearings and have come  across a couple of problems.

The first problem up, is when I removed the third member and inspected it I found that it had a crack running  through the rear pinion support rendering the third member scrap for my use, so I have decided to build an totally new third member assembly to my specs. I now need to choose a third member, there a several I am looking at:

Summit racings nodular iron case

Strange engineering's S nodular iron case

Strange engineering's Pro series case ( preferred choice )

Are there any other cases I should be looking at.

Next problem is too do with the axle shafts, being that my shafts are 28 spline at the moment and the engine will be producing around  380 too 450 BHP ( flywheel ) with possibly about 400 foot pounds of torque, what's the opinion on my shafts living with these power levels, would it be worth upgrading to 31 spline ( which I am trying to avoid due to the cost ) plus I have a small bearing axle so I will need the special bearings for this conversion and I have been told that these special bearings are no good for street use because they are too small and burn up ( have been told that I need to have large bearing hubs fitted to my axle which also means new back plates and drum assembly's ), I need people's opinion if this is true or not.

I will fitting a Daytona pinion bearing conversion ( probably a Strange iron one ) and a corresponding yoke, I will also be using Timken bearings where possible.

I  am looking at an Eaton Truetrac LSD or should I be looking at a plate type LSD.

Lastly I will also be getting a new crown wheel  and pinion, I was looking at a ratio of 3.70:1 do you think this is ok or should I look at any other ratios as the car will mainly be used for shows and will not see hardly any motorways ( I will also be fitting an 4r70w at a later date ). Also any crown wheel and pinion makes recommended and any I should avoid.

A few specs on the engine and gearbox:

351c, 3v alloy heads, solid lifter Lunati 411A1 cam, other internal mods to match the cam, sequential injection and spark, headers, 2.5 inch bore exhaust system.
FMX gearbox with a B&M shift kit fitted and will be getting a 2800 stall converter.

Any help and advice is greatly appreciated.
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#2
Try these guys they ship world wide, and make an excellent product. I would run a 3.70 gear.
https://www.quickperformance.com/Ford-9-..._p_36.html
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#3
A lot to think about. As far as the 3rd member case I know Strange has a good track record. For ring and pinion I have always had good luck with Yukon and Richmond. A 3.70 will work fine for just local driving. You will be turning around 2800 rpm @ 65 mph. I currently am running a 3.70 with a 2800 stall behind a built up 460 with C6. Don't know about the special bearings. A 28 spline axle will hold up to around 400 rear wheel horsepower before the sound of inevitability, the snap you hear when the axles break under heavy acceleration. If you can squeeze the dollars I would switch to a 31 spline. They are about 30% stronger. You could try to find a good used housing if going to go that route and save a few dollars. Figure around $300 to $500 for a set of axels. You will be better off to do it now if you can afford it.

Kilgon


"The only dumb question is the one not asked"
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#4
(09-08-2019, 11:42 PM)Kilgon Wrote: A lot to think about.  As far as the 3rd member case I know Strange has a good track record.  For ring and pinion I have always had good luck with Yukon and Richmond.  A 3.70 will work fine for just local driving.  You will be turning around 2800 rpm @ 65 mph.  I currently am running a 3.70 with a 2800 stall behind a built up 460 with C6.  Don't know about the special bearings.  A 28 spline axle will hold up to around 400 rear wheel horsepower before the sound of inevitability, the snap you hear when the axles break under heavy acceleration.  If you can squeeze the dollars I would switch to a 31 spline.  They are about 30% stronger. You could try to find a good used housing if going to go that route and save a few dollars.  Figure around $300 to $500 for a set of axels. You will be better off to do it now if you can afford it.
With 3.70 gears...."You will be turning around 2800 rpm @ 65 mph." Are you sure about this? I am running my cleveland with a C6 AND 3.50 gears and a truetrac antislip. I register 3,200 on the tach. I plan to go to 3.25 or 3.00 gears to reduce the rpms and be able to take the car on longer trips.
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#5
At 65 MPH with 3.70 gears and a 1:1 final drive ratio, assuming a 26" tall tire your RPM would be 3,109. With a 3.50 all else the same it would be 2,941. He did mention installing a 4R70w at some point, the final drive on that being 0.667 putting the 65 MPH RPM at 2,074 with the 3.70 gears and 1,962 with the 3.50 gears. Hope this helps.

73 Grandé H Code. Headman long tube headers, T-5 Transmission, 3.70 Traclok, Lowered 1" all around, Aussie 2v heads w/ 2.19 intake, 1.71 exhaust, screw in studs, full roller cam 608/612 lift 280/281 duration LSA 112, Quick Fuel 750 CFM double pumper, AirGap intake.

- Jason


[Image: 082-hot-rod-power-tour-2017-1970-1970s.jpg]
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#6
https://www.moserengineering.com/1971-73...ne-31.item



I'd run forged axles with that kind of power unless you plan on running hard narrow rear tires as the fuse.  You have 2 choices with 31 spline axles- you can run "large bearing" 31 spline axles in a small bearing housing using the goofy conversion bearings - or you can give up a small amount of strength and run 31 spline axles that are for a small bearing housing - and use the stock small bearings.  Maybe contact Moser or the manufacture of your choice and see what they suggest.

Stock 28 spline small bearing shaft OD is 1.378"
Stock large bearing shaft OD is 1.562"

As for the third member - any nodular iron option should be fine.
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#7
(09-09-2019, 11:35 AM)rackerm Wrote:
(09-08-2019, 11:42 PM)Kilgon Wrote: A lot to think about.  As far as the 3rd member case I know Strange has a good track record.  For ring and pinion I have always had good luck with Yukon and Richmond.  A 3.70 will work fine for just local driving.  You will be turning around 2800 rpm @ 65 mph.  I currently am running a 3.70 with a 2800 stall behind a built up 460 with C6.  Don't know about the special bearings.  A 28 spline axle will hold up to around 400 rear wheel horsepower before the sound of inevitability, the snap you hear when the axles break under heavy acceleration.  If you can squeeze the dollars I would switch to a 31 spline.  They are about 30% stronger. You could try to find a good used housing if going to go that route and save a few dollars.  Figure around $300 to $500 for a set of axels. You will be better off to do it now if you can afford it.
With 3.70 gears...."You will be turning around 2800 rpm @ 65 mph." Are you sure about this? I am running my cleveland with a C6 AND 3.50 gears and a truetrac antislip. I register 3,200 on the tach. I plan to go to 3.25 or 3.00 gears to reduce the rpms and be able to take the car on longer trips.

Sorry on that.  If running a standard 205/75 14 (26" diameter) rpm will be around 3100.  I don't know where the 2800 came from. I think I was thinking of the stall converter when I typed the rpm. My tach reads about 3000 - 3100 on mine at 65mph.

Kilgon


"The only dumb question is the one not asked"
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#8
I forgot to mention my tyre size which is at the moment 255/60 15 cooper's ( 27 inch tall ) and I my be changing it for a 275/60 15 BFG not long after the car goes back on the road.
I did look at quick performance and had considered them but I know someone over here ( UK ) that got a quote on shipping and they were very expensive to ship out of the USA, but I will keep them in mind as they have the cheapest complete third members that I have come across that aren't unnamed.
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#9
I used quick performance as well and was very happy. But as I am in Iowa as well shipping was very cheap for me.

73 Grandé H Code. Headman long tube headers, T-5 Transmission, 3.70 Traclok, Lowered 1" all around, Aussie 2v heads w/ 2.19 intake, 1.71 exhaust, screw in studs, full roller cam 608/612 lift 280/281 duration LSA 112, Quick Fuel 750 CFM double pumper, AirGap intake.

- Jason


[Image: 082-hot-rod-power-tour-2017-1970-1970s.jpg]
  Reply
#10
Quick Performance definitely would have all the parts you need. Out of the hundreds of high performance site's across the US another couple you might try are https://www.speedwaymotors.com/ - https://www.summitracing.com and https://www.jegs.com. They have comparable prices to most of the other speed/performance sites. Don't know how shipping to your side of the pond will compare to other stores or if they even ship overseas.

Just out of curiosity how available are the high performance parts over there locally?

Kilgon


"The only dumb question is the one not asked"
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