How much can you narrow rear axle with a mini tub kit?

[lancef53]

Working on a 73 Challenger, installing a level 3 USCT kit in prep for a gen 3 hemi swap. Currently planning on a 9" rear to replace the 7 1/4 in the car. With the couple inches of extra room per side, is it best to go with a 4" or so narrower axle? The plan is to use a 4 link/coil over setup in place of leaf springs. I haven't sourced wheels/tires yet, so I still have flexibility.
Thanks for any advice!

 

[Steve340]

It would pay to get the wheels/tyres and adjust the rear axle width to work with the wheels and suspension set up.

 

[6PKRTSE]

Yes, correct. I bought the wheels and tires first that I knew would fit in the mini tub that I did first on my blue 70 Challenger. Then we measured and cut with dimensions that I was able to figure out from the Strange Engineering axle flanges and rotor thicknesses. I don't recall how much I cut off each end, but it wasn't much since my Dana 60 axle originally started off as a narrower 1 ton dually axle.

 

[lancef53]

Thanks for the replies. Is the Dana 60 from a pickup the same center/tubes as what was in the cars?

I was just curious if people normally narrowed up the rears when they do the mini tub kit. I prefer the look with a little more dish on the outside, compared to the newer vehicle setups.

 

[HPP]

If you are doing a pro street layout, it really depends on the offset you want to run on the wheels to determine how wide the axle needs to be.

I've done some mental gymnastics around wider front track width to play with scrub radius geometry which would also require a wider rear track in order to maintain the square tire size I'm currently pursuing. That's a whole different animal that what your after.

 

[6PKRTSE]

Thanks for the replies. Is the Dana 60 from a pickup the same center/tubes as what was in the cars?

I was just curious if people normally narrowed up the rears when they do the mini tub kit. I prefer the look with a little more dish on the outside, compared to the newer vehicle setups.

My truck Dana does have extra thick axle tubes. They are thicker than car Dana's. I think they were like 3/8" wall or slightly over. I agree with depth on wheels. I went with 15"x12" with a 6" back space.

 

[lancef53]

If you are doing a pro street layout, it really depends on the offset you want to run on the wheels to determine how wide the axle needs to be.

I've done some mental gymnastics around wider front track width to play with scrub radius geometry which would also require a wider rear track in order to maintain the square tire size I'm currently pursuing. That's a whole different animal that what your after.

Not really a pro street layout, kind of a low level pro touring deal. Just trying to determine if i can get away with moving stuff in a little to get some dish on the rims. I won't be having square tire setup.

Thanks!

 

[heminut]

The truck Dana 60 I have doesn't have the mounting points for a pinion snubber. I don't think any of the truck Dana 60s do.

 

[6PKRTSE]

The truck Dana 60 I have doesn't have the mounting points for a pinion snubber. I don't think any of the truck Dana 60s do.

Good reminder. No, truck Dana rear axles do not have mounting points for the pinion snubber. I run Caltracs with split mono leafs so it was never an issue for me.

 

[HPP]

Still comes down to how much dish you want to achieve.

The Challenger wheel well will accept a 335 wide tire, depending on how tall you go, without a mini-tub. Since you say pro touring more so than pro street, I'll assume a 26" no more than 27" overall height. This should fit in the tub without issue, even with a very low ride height.

The stock E body housing width flange to flange is 61.625" With a 10" wide wheel, assuming springs are mounted at least 1" inboard of the stock location, I'm thinking you would get about 3.875" of dish visible from the outside.

I use a '67 B body housing, 59.375" flange to flange, in my Challenger. With a 10" wide wheel and I have almost 5" dish because I have 5" backspace on my rims. I have retained leaves but moved them in 1' per side. With a four link, I would think your springs will be further in and the rear segment of the frame rail will now become your limiting factor. Picture below with a 26x12 tire on the 15x10 rim.

If you want more dish than this, then you would need to narrow the flange position 1:1 for every inch of wheel depth you want to achieve.

FWIW, the fronts are 15x8 with 4.5" backspace and a 26x10 tire.