Narrowing axle dimension Questions???

[zpsull01]

Here's the thing. I'm having a Dana 60 narrowed for my 72 Duster and I need to know what measurements exactly will allow for my set up to work. I have mini tubbed the wheel wells and have recently ordered the street lynx system. I want to run an 18"x10" rim with a 26.5" to 28" tall tire that has a sectional width between 10.5" and 12". The rim that I am wanting to run only comes in a 6.5" backspacing. If I remember correctly in order to center a 10" rim in the widened wheel well you need a backspacing of 7.5" on a stock axle, Is this correct? I can't seem to find that information again. If that is correct then I would need to have a flange to flange width of 49.40". But that is just flange to flange, not including the rotor/drum thickness. I plan on having the big ford ends with either the explorer or crown vic disc brakes.

So basically how do I go about acquiring this information to figure out exactly the width of the rear to place a 10" wide rim in the wheel well with a 6.5" backspace?

[bOb shingler]

you should be able to find that in a chassis engineering catalog.

[zpsull01]

What kind of chassis engineering book? I have the Mopar Performance Chassis book and I have skimmed through it(haven't read it) but I didn't see anything about this. What do you recommend?

[Ace]

All the rear end shop will need is your flange to flange measurment.  I had 9" ends put on my Dana too.  If you currently have the wheels, the best bet is to set 'em up under the car, and measure, but tell the shop that's what your measuring.

[bOb shingler]

it's not a book, it's their company catalog. they are here in florida. the make all kinds of race car components.  "Chassis Engneering"

[zpsull01]

Oh my bad. I was wondering about that when you said catalog. I'll give that a look and I don't have the wheels yet but if I hang a plumb line in the center of the wheelwell and account for my backspacing, Hence if I have 6.5" of backspacing on a 10" rim then add 1.5"s to both sides, and get a total measurement. Will this work?

[jwmotors]

You better get your wheels first

[Mopartist]

Set your wheel/tire combo in the wheelwells first and make sure you have clearance (ie; for tire growth and cornering. I've been told 3/4 inch should do)  Measure the distance between the inner mounting surface on your wheels. If you've narrowed your leaf springs; measure the distance between the centers of the center pins on the leafs. Thats all your diff shop should need to narrow your diff.

[zpsull01]

I'm not running leafs. I just ordered a Street Lynx system with coilovers from RMS. But basically it is a must to have the wheels and tires first?

[*DB*]

I'm not running leafs. I just ordered a Street Lynx system with coilovers from RMS. But basically it is a must to have the wheels and tires first?

It's not a MUST but it certainly makes one's life easier to KNOW how wide the rear should be & that the tire/wheel combo will fit. If one of your measurements is off enough, then you end up spending money to work around the mistake, so in the long run it could be less expensive, too!

BTW, that's how I came up with the width of the rear in my Dart: Mounted the tires on the wheels, used blocks to set them centered in the wheel wells, & measured between the wheels. Sent the axles to Moser & told them how wide I wanted the "flange to flange" to be, then narrowed the housing to fit the axles (I'll never do THAT again, Moser will get both axles & housing).

[7173Duster]

I went to Summit Racing in Akron, OH  and had them pull out two different rims, convo pro's and draglites, the backspacing on both rims was close to the catalogue but not exact, a 5" centerline had 4.75 by my measurements and the weld were off something like .125 off.  It even seemed to vary by wheel width. 

You can get really close with the plumb bobs and a tape measure, but nothing works like having the tires in place then measuring the distance to the back side of the rim through the center hole then subtracting the thickness of your drum or rotor depending on what brake setup you are using. 

Short version is buy the tires and wheels first, the tires never have the same section width as in the catalogue and backspace never matches either. 

[zpsull01]

First of all thanks for all the help.

So ideally the best and most accurate way to do this is to

Get the wheels and tires mounted
Place them in the wheel wells where I want them
Measure the distance
Get the brake set up that I am planning on using for the thickness of the rotor
Subtract that from the overall width and have it cut down to that flange to flange

BTW, that's how I came up with the width of the rear in my Dart: Mounted the tires on the wheels, used blocks to set them centered in the wheel wells, & measured between the wheels. Sent the axles to Moser & told them how wide I wanted the "flange to flange" to be, then narrowed the housing to fit the axles (I'll never do THAT again, Moser will get both axles & housing).

How much will it cost to have it all done my Moser? There is a renowned local service around here that has done this for 20+ years and their price is $150 to have it cut down, axles re splined, and set back up. I am thinking heavy about using Moser axles though.

Also what is the best brake system (off what vehicle) that uses the big Ford ends?

[*DB*]

This was 1999, but the axles (that I supplied), cut & resplined, were $80 (plus shipping). I'm quite sure that today their prices, with shipping, would be nearly the same as your local place.

[zpsull01]

Well I can get moser axles for $309 at any length I want but that $150 is me taking him the rear, telling him how short I want it, and him giving it back ready to be bolted into the car.

[*DB*]

That's a great deal! Go for it!

[7173Duster]

I had right around $500 in getting a rear narrowed by Moser, axles, studs, bearings, retainer plates and shipping.  Don't go with a resplined axle if you are going to make any amount of power or use slicks.  Another thing to check is what your pinion angle is now and if it needs any adjustment have the perches cut off and moved accordingly while they are working on the rear end.  That way you don't have to run any shims.

[Mopartist]

Also what is the best brake system (off what vehicle) that uses the big Ford ends?

I purchased a new Dana 60 with big Ford ends from Strange. They used Torino ends.

[zpsull01]

I had right around $500 in getting a rear narrowed by Moser, axles, studs, bearings, retainer plates and shipping.  Don't go with a resplined axle if you are going to make any amount of power or use slicks.  Another thing to check is what your pinion angle is now and if it needs any adjustment have the perches cut off and moved accordingly while they are working on the rear end.  That way you don't have to run any shims.

I don't understand about the pinion angle. The car is currently stripped all the way down and is waiting to be assembled after a fair amount of body work. I just want to get this cut down so I can get the car rolling again.

Also as for the brakes, would any disc set up used on a 9" ford work with the late model big ford ends? Where can I find more info about this?

[7173Duster]

Pinion angle is one of the most important things that must be correct if you want you rear suspension to work properly.  If the car is disassembled there is no way to properly measure or set the pinion angle.  Pinion angle must be checked and set with the cars weight on all four wheels and is about the last thing that you check and set after the car is put together.  If you need something so the car can be rolled around see if someone who lives near you has a junk rear end they will give you or you can buy cheap to put under it. 

Disc brake info can be found on wilwoods website, strange engineering, mark williams, ssbc, etc.