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View Full Version : 2nd gen fbody- What do measure for new axle, rear, and 12" wheels



Schroeder
06-27-2015, 10:17 AM
All on a 77 TA.


Guys, I'm preparing to get a new moser rear end, DSE quadralink, mini tubs, and new 18" wheels that are 12" wide. I'm gonna put 335s on em pf course. I'm wondering what I should all be measuring and checking. I want to make sure I don't miss any of the "measure twice" steps before I "cut" because the axle and wheels Re going to be made to the lengths and backspacing I specify. I want a deep dish look. I'm getting the year one billet snowflake wheels like on their BRE US and I want the car to look like that in stance and with the deep dish wheels. I believe its a 4.5-5.5" backsppacing according to what year one has told me. I'm also looking for nominal dimensions on the track widths of these cars and how much I need to shorten it. My plan was to measure the rear axle's mounting surface to mounting surface of the wheels, measure the disrance from the outside of each frame rail to the outer fender lip (I plan on rolling the inner fender lip), and finally calculating where my 12" wheel needs to sit to not hit the fender and have the 4.5" backspacing. Id center the wheel in the space between the frame rail and the fender lip. I want the 4.5" backspacing, matbe 5 or 4.75" for that really deep look. These facts and calculations could tell me how long my axle needs to be. Is this what u guys all do? Is there a standard I csn hust go by since this has been done so much, so I can save me and my wife from having to plumb Bob and measure a bunch of crap? She gets cranky when she has to help too long.

I was also gonna do the same thing on the front to see if I can get a 10" wheel on the front and where the backspacing would be to keep the interferences to a minimal. This sounds like it's not possible or a huge headache though on these second gen fbodies.

Also, I have heard that the rear in these cars is not centered but is towards the passenger side by some dimension. I can see this on my car. Has anyone left the rear end not completely centered to keep the driveline all the same, but then shortened their PA axle by 1/2-1/4" to make it look like the rear axle is centered in the car? I have recently been advised against this as it also requires off centering the suspension mounts, but since it's going to be a custom quadralink im not sure if that's really an issue.

So, what steps do I all have to go thru before getting this work done. I think I know what I want, but I've been spinning my wheels without spending any dollars to try and absorb as much info as I can so I get exactly what I want and do this right without missing any crucial measurements.

This pic shows the car and some of the features I planned on paying special attention to.

Schroeder
06-28-2015, 07:52 AM
Bump

csouth
06-29-2015, 07:15 AM
Have you tried calling DSE? It would seem since you are using their Quadra Link they could offer some insight. Measuring WMS to WMS is the proper way to do it. As long as you know the 12" wheel will fit, you should be able to order the wheels and build the rear around the wheel once it arrives. Once that is verified, I would order the wheels. It will take the wheels a lot longer than it will take the rear to be built. Moser will probably be able to ship your housing within 5-7days, most wheels take 4wks

Schroeder
06-29-2015, 03:09 PM
What is WMS to WMS? So you think I should have the wheels first? Can't this be figured out mathematically though without mocking anything up?

csouth
06-29-2015, 04:41 PM
What is WMS to WMS? So you think I should have the wheels first? Can't this be figured out mathematically though without mocking anything up?

WMS= Wheel Mount Surface. I this case it would be the back of the wheel that sits against the rotor. Figuring this out mathematically is a difficult, but not impossible when you start using wheels the are outside the with that requires a tub and modified rear. Remember these are cars that were built in the '70's, the margin for error could be a lot smaller as dimensions can vary from car to car. Believe me, there are lots of people the order a rear around a wheel. Its actually harder to make a mistake this way.

Schroeder
07-01-2015, 04:18 PM
But cant I just find the thickness of the rotors? I know I want the wheel x" from the fender lip and I want x backspacing, so I should be able to find my axle width.

Anyway, if I do it ur way I order the wheels I want, center them in the well while the car is on jacks, and then measure from WMS to WMS, subtract the thickness of a rotor, and that is my axle length?

Seems I could get this by measurement and math.

csouth
07-01-2015, 05:17 PM
But cant I just find the thickness of the rotors? I know I want the wheel x" from the fender lip and I want x backspacing, so I should be able to find my axle width.

Anyway, if I do it ur way I order the wheels I want, center them in the well while the car is on jacks, and then measure from WMS to WMS, subtract the thickness of a rotor, and that is my axle length?

Seems I could get this by measurement and math.

Rotor specs can be found easer than an unknown axle length for unknown wheels. You are on the right track with your process of how it should be done. This question has been asked before, I'm not pulling my answers out of the sky....

https://www.pro-touring.com/threads/94558-1968-Camaro-rearend-width

Here the guy even states he called DSE as I suggested to get the measurements or at least some assistance.

https://www.pro-touring.com/threads/84472-Question-on-how-to-measure-rear-end-width

I would think if you're getting ready to spend 3k+ DSE would be able to offer some assistance before you buy

Schroeder
07-03-2015, 05:22 AM
Those are great threads. Especially the first one with the link to the chris alston worksheet. That is something that I was envisioning. Even the alston worksheet makes references to the tires you have though. Choosing the axle size seems to depend on EXISTING wheels. I find this very strange that this is the only way to do this.

Schroeder
07-03-2015, 06:29 AM
I may start a dedicated thread to this, but I'll ask here too. Is 4.5" back spacing too radical on a 18x12 wheel? Does that put the axle too far off centered from the center of the tire? DSE and my wheel manufacturer said they commonly do 5.5" back spacing but year one said they do do some 4.5". When I asked DSE about it they said it can be done and they do it. It may be a non issue because overall I've heard people say it can be done without issue. There have been a couple guys tell me that it's too far off center, makes improper loading on the wheel and bearing, and has other negative effects. Is this true?

I want the 4.5" backspace to achieve that really deep looking wheel, but if I'm going to be losing more than I'm gaining I won't do it. I never like to sacrifice handling, ride quality, etc. or structural integrity. If I'm not sacrificing THAT much though, I'll still go with the 4.5". :cool: