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Discussion Starter #1
Ok,

Here's the FULL question....

Do solid axle cars and IRS cars, in the differentials, use the same ring and pinion gears?

I've got a friend that has 3.55 gears in an 8.8 diff solid axle in his Explorer that wants to get more fuel efficient, and wants me to see if I can get him a higher gear ratio, so I've found a set of 2.73's out of an SC 5 spd, and want to know if they will work in his solid axle truck?

Yes I know that his torque and pulling capacity are going to suck, and I warned him of this, but he uses this truck for a commuter, and not for a tow vehicle.

I may just try and get him a spare axle for the back and set it up that way so that if he wants to use the truck for towing we just swap the axle in.
 

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Yes.
 

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Gear

Hello

They will fit. But make sure he disables 4WD.

also this would be OK if is an ALL highway commute. He might consider 3.27's first if not. Might have to get a chip & A speedo change.

Paul
 

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So if I get a 8.8 trak-loc from say a solid axle mustang it will work in my t-bird IRS? If so does anyone know what the average price places cost to shim them up properly. I ask because I scored a 8.8 unit for $65 awhile back for my truck but was thinking about throwing it in my bird instead.
 

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Discussion Starter #5
There is one BIG issue with that. If the truck had halfshafts, then you can swap the IRS in its entirety. If it was a solid axle, then you CAN'T...unless you want to make your bird a solid axle...:D

If you just want to swap the internals...then you can.
 

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Discussion Starter #6
Hello

They will fit. But make sure he disables 4WD.

also this would be OK if is an ALL highway commute. He might consider 3.27's first if not. Might have to get a chip & A speedo change.

Paul
Paul,

I'm running a stock EEC in my 97 with the 2.73's. I'm going to look into getting a custom burn for just that reason, but right now, I'm doing HIGH 28's low 29's in MPG with just the diff swap.

I am going to get my buddy a speedcal for his explorer. For now, I did warn him to NOT use the 4WD, and I'm probably going to disable it by unplugging the cable when I'm in there to make sure that it doesn't get all screwed up.
 

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So if I get a 8.8 trak-loc from say a solid axle mustang it will work in my t-bird IRS? If so does anyone know what the average price places cost to shim them up properly. I ask because I scored a 8.8 unit for $65 awhile back for my truck but was thinking about throwing it in my bird instead.
No you can not. The solid axle trak-lok uses different side gears. The first question was asking just about the ring and pinion, and re-using your existing IRS differential. To use a solid axle trak-lok, you would need to either have the side gears machined, or use a set of side gears for an IRS trak-lok.
 

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No you can not. The solid axle trak-lok uses different side gears. The first question was asking just about the ring and pinion, and re-using your existing IRS differential. To use a solid axle trak-lok, you would need to either have the side gears machined, or use a set of side gears for an IRS trak-lok.
or....if you really want to do this, take the cir-clips off the axles, and it will work.
 

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True, however having never tried that myself, I don't feel comfortable reccomending it to someone else.
 

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Understandable.

I would only suggest you using my method maybe for race only.



here come the flames.
 

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I don't think you guys understood what I was asking. I have just the trac-loc its self from a 8.8 no gears, housing, ect. I was asking will it work in our carriers. I had been asking about shims because if I change the unit out won't I have to reshim it so it sits in there properly not to tight not to loose or is that just when I do gear change?
 

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I don't think you guys understood what I was asking. I have just the trac-loc its self from a 8.8 no gears, housing, ect. I was asking will it work in our carriers.
MadMikeyL answered this in post #7.

No you can not. The solid axle trak-lok uses different side gears. The first question was asking just about the ring and pinion, and re-using your existing IRS differential. To use a solid axle trak-lok, you would need to either have the side gears machined, or use a set of side gears for an IRS trak-lok.
Joe
 

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Side gears

Hello

You must get a bevel cut into a NON-IRS trac-lok side gears. Other wise you will NOT be able to get the Axles OUT!

But the Ring & pinion will fit into your current housing.
8.8=8.8
7.5=7.5
I have
7.5 -- 4.10's from solid in IRS housing ( came from a VAN with trac-lok)
7.5 -- 3.73's from solid in IRS housing (came from 80's Mustang)
8.8 -- 3.90's Motive gears in IRS housing (purchased NEW)
8.8 -- 3.55's out ( from 87 Bronco)
8.8 -- 3.08's out for sale( from 95 T-bird)
7.5 -- 3.27's out for sale( from 90 T-bird)
7.5 -- 3.27's in housing (still Bolted in a 96 T-bird)

I run an open rear due to racing rules. I used the side gears from original IRS housings. I run my 90 T-bird on an 1/2 mile Asphalt Oval.
the 96 is my back-up, How-ever not built yet. lol

Paul
 

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MadMikeyL answered this in post #7.
Joe
Ah I was a littel confused on that so a solid axle trac lok will work but you have to have the gears from a IRS trac lok.... So basically it IS the same unit then but you have to have gears designed for a trac loc unit. Probably be easier to just swap the whole IRS unit at that rate.



Hello

You must get a bevel cut into a NON-IRS trac-lok side gears. Other wise you will NOT be able to get the Axles OUT!

But the Ring & pinion will fit into your current housing.
8.8=8.8
7.5=7.5
I have
7.5 -- 4.10's from solid in IRS housing ( came from a VAN with trac-lok)
7.5 -- 3.73's from solid in IRS housing (came from 80's Mustang)
8.8 -- 3.90's Motive gears in IRS housing (purchased NEW)
8.8 -- 3.55's out ( from 87 Bronco)
8.8 -- 3.08's out for sale( from 95 T-bird)
7.5 -- 3.27's out for sale( from 90 T-bird)
7.5 -- 3.27's in housing (still Bolted in a 96 T-bird)

I run an open rear due to racing rules. I used the side gears from original IRS housings. I run my 90 T-bird on an 1/2 mile Asphalt Oval.
the 96 is my back-up, How-ever not built yet. lol

Paul
Thanks for the info Paul
 

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So basically it IS the same unit then but you have to have gears designed for a trac loc unit.
The traction lok is the same. You need side gears for an IRS traction lok.

Joe
 

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Hello

You must get a bevel cut into a NON-IRS trac-lok side gears. Other wise you will NOT be able to get the Axles OUT!

But the Ring & pinion will fit into your current housing.
8.8=8.8
7.5=7.5
I have
7.5 -- 4.10's from solid in IRS housing ( came from a VAN with trac-lok)
7.5 -- 3.73's from solid in IRS housing (came from 80's Mustang)
8.8 -- 3.90's Motive gears in IRS housing (purchased NEW)
8.8 -- 3.55's out ( from 87 Bronco)
8.8 -- 3.08's out for sale( from 95 T-bird)
7.5 -- 3.27's out for sale( from 90 T-bird)
7.5 -- 3.27's in housing (still Bolted in a 96 T-bird)

I run an open rear due to racing rules. I used the side gears from original IRS housings. I run my 90 T-bird on an 1/2 mile Asphalt Oval.
the 96 is my back-up, How-ever not built yet. lol

Paul
How long will a 7.5 rear end last in a 4.6 application?

My buddy has a 7.5 locker I can have...
 

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There really isn't a set amount of time it will last. It depends mostly on how you drive the car. If you go to the track a lot, you could blow it up first time out. If you never get on it hard from a stop, it would probably last as long as an 8.8 would.
 
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