69 Camaro backspace with DSE tubs & rear end length

[Cdog]

I’m in process of ordering a Art Morrison Tri-4 bar for my 69 Camaro and am stuck on the wheel backspace to rear end width measurement. The math says if I run a 47 inch rear end I would end up with a 4 inch back spaced wheel and with a 55 inch rear end I’d end up with 8 inches of backspace. Is there a preferred amount of backspace for the wheel to function and look good? Are there concerns about brake packages etc that I need to add to the equation? Is there a common backspace like 5.5 inches that I should shoot for?

Here’s a picture of the beast.
74412


Thanks in advance!

Corey

[TheJDMan]

Here are some numbers from my 68 build.

Rear end width is 57" WMS to WMS.
Rear wheels are 18x12 with a 5.6" back space.

I purchased my wheels/tires first with the look I wanted and then mocked them up under the car with the Mini-tubs installed. With the wheels in the location I wanted under the car, I measured the exact distance between the wheel mount surfaces to determine the width of the rear end.

I don't know what kind of math you are doing but with a 47" rear end width I'm not sure you would have enough room to install brakes. Also keep in mind the only measurement that means anything is WMS to WMS. See this thread for more detailed info on what WMS is.

https://www.pro-touring.com/showthread.php?93536-What-is-the-WMS-measurement-(Wheel-Mount-Surface)

Here is a pic that I have not posted before, if you look close you can see the mock up axle that I made out of exhaust tubing to locate the wheels and to determine the exact rear end width I needed.

74419

[Schwartz Performance]

What wheel size are you thinking about? 12" wheels are good. And a 56" in my opinion looks great. Take a look at the 2 Camaro's on our site for the look. The back spacing slips my mind at the moment. But thejdman has a good idea.. 47" may be a bit narrow.

[Cdog]

I did quite a bit of research today online and found a 5.5 backspace to be a good looking combo. My plan is to run 18x12 wheel with 335 tires. What are your guy’s thoughts. I asked the guy at AME to do the math and tell me the rear housing length. I should have the info in the morning. The math for the previous estimates came from a sales guy at AME.

[Cdog]

Here are some numbers from my 68 build.

Rear end width is 57" WMS to WMS.
Rear wheels are 18x12 with a 5.9" back space.

I purchased my wheels/tires first with the look I wanted and then mocked them up under the car with the Mini-tubs installed. With the wheels in the location I wanted under the car, I measured the exact distance between the wheel mount surfaces to determine the width of the rear end.

I don't know what kind of math you are doing but with a 47" rear end width I'm not sure you would have enough room to install brakes. Also keep in mind the only measurement that means anything is WMS to WMS. See this thread for more detailed info on what WMS is.

https://www.pro-touring.com/showthread.php?93536-What-is-the-WMS-measurement-(Wheel-Mount-Surface)

Here is a pic that I have not posted before, if you look close you can see the mock up axle that I made out of exhaust tubing to locate the wheels and to determine the exact rear end width I needed.

74419

Excellent link. Thank you.

[Todd in Vancouver]

I am watching this carefully as I will soon be in the same position and I've planned on running a 18X12 on the back as well. That's what makes this such a great website with so many well informed helpful people.

[Schwartz Performance]

We did a 6.2" BS on this 69 attached. It has a 56" rear end- 335 tire, and about 1/2" clearance between tire and 1/4 panel lip.

Keep in mind that most companies have specific wheel hoops to work with- which means that the mounting hub thickness on the wheel changes a bit based on the BS you want. So even though this is a 6.2" BS, a 6" or 6.5" BS may not even change the look of the wheel from the outside.

74436

[Cdog]

We did a 6.2" BS on this 69 attached. It has a 56" rear end- 335 tire, and about 1/2" clearance between tire and 1/4 panel lip.

Keep in mind that most companies have specific wheel hoops to work with- which means that the mounting hub thickness on the wheel changes a bit based on the BS you want. So even though this is a 6.2" BS, a 6" or 6.5" BS may not even change the look of the wheel from the outside.

74436

Wow! Great post and info, thanks! So by looking a this set up If I went with a 54 inch rear end I should have somewhere between 5-5.5 inch backspacing using your same brake set up. Is that correct? What brakes are you using on that rear end?

[Ron.in.SoCal]

Hey Corey...above posts are on point. Pad depth would be key. Also rear end manufacturer/axle type as well as brake rotor hat thickness will efffect WMS.

Original set up on my 69, Moser 9" sealed bearing and Baer brakes: 50" housing length, 31 spline sealed bearing axles (2.5" each side), .25" rotor hat, Forgeline 18x12 wheels 5.75 BS gave me about a 5.5" wheel lip.

Key to all this will be inner wheel tub clearance under shock compression.

Hope this helps!

[Cdog]

Hey Corey...above posts are on point. Pad depth would be key. Also rear end manufacturer/axle type as well as brake rotor hat thickness will efffect WMS.

Original set up on my 69, Moser 9" sealed bearing and Baer brakes: 50" housing length, 31 spline sealed bearing axles (2.5" each side), .25" rotor hat, Forgeline 18x12 wheels 5.75 BS gave me about a 5.5" wheel lip.

Key to all this will be inner wheel tub clearance under shock compression.

Hope this helps!

Ron,

Good to hear from you. Thanks for the input. This whole wheel fit rear end length has a lot of variables to work with. We’re attempting to get back out there with you guy’s with this 69. It’s a budget build daily driver type. Hopefully we can pull it off.

Are the C6 type rear brakes comparable to the thickness of the Baer brakes?

[Schwartz Performance]

The rear end used in our application is a full-floater so there is no rotor hat to affect the WMS measurement.. So as Ron stated you'll have to take the brake kit into consideration! Most hats are .25" so that'd be a 1/2" reduction - 55.5" axle face to axle face.

[csouth]

Ron,
All good points have made here. I second the fact about about knowing your pad thickness. Try to have an idea of what brakes you will be using because spoke clearance is vital. The only place where pad height is not and issue would be if you use a floater like Schwartz Performance or Steve(theJDman)

[TheJDMan]

I'm also running a full floater rear end from Moser. Note in the pic below that the rotors are attached to the inboard flange of the hub which results in the entire brake package setting a couple of inches inboard behind the wheel. I highly recommend that you do not use someone elses measurements (including mine) they will get you in the ball park but you may or may not like it. Buy the wheels/tires and mock them up where you want them under your car. I was told by Frank to use a 56" WMS to WMS dimension with a 5.6" bs but when I mocked up that dimension under the car I felt the wheels were too far inboard for my taste. I moved my wheels out 1/2" per side and liked the look much better and I still have a good 3/8" clearance once the fender lips were rolled. IMO, a 18x12 5.250bs with a 56" WMS would be very close but buy the wheels/tires first and determine what works best for you under your car.

74557

18x10 275/35-18 6.6" BS front and 18x12 335/30-18 5.6" BS rear

163003

[icemanrd19]

Forgeline
Model GA3
size 18x11
offset 25.4
b.c. 5/4.75
hub 70.3
finish trans smoke
application camaro

DSE quadralink standard width. One thing i can tell you is that i want my car low and i felt with a 335/30/18 and a 12" wheel i wouldnt be able to really get it in the sweet spot. Hell i was even told that a 18x9.5 wouldnt fit without rubbing on a 67 with the dse front subframe. I took a chance by going with a 28.58 offset on the front and OMG its perfect. The 18x9.5 and 18x11s are perfect. i can go lower than this too.
https://static1.pt-content.com/images/pt/2013/03/IMAG0327-1.jpg
https://static1.pt-content.com/images/pt/2013/04/IMAG0325-1.jpg
https://static1.pt-content.com/images/pt/2013/04/IMAG0324-1.jpg

[icemanrd19]

alot of autocross guys are switching to a 315 for faster lap times. 335s tend to push. A 275/35/18 and 315/30/18 are pretty much the exact same height and with this rim and riire combo everything is spot on. from overall diameter, tire bulge, manufacture recommended tire to wheel specs.

If you really want to be safe get a 18x11.5. That way if you go with a 335/30/18 and it rubs some you can then switch to a 315 and it will still look great on the rim.

[Cdog]

Forgeline
Model GA3
size 18x11
offset 25.4
b.c. 5/4.75
hub 70.3
finish trans smoke
application camaro

DSE quadralink standard width. One thing i can tell you is that i want my car low and i felt with a 335/30/18 and a 12" wheel i wouldnt be able to really get it in the sweet spot. Hell i was even told that a 18x9.5 wouldnt fit without rubbing on a 67 with the dse front subframe. I took a chance by going with a 28.58 offset on the front and OMG its perfect. The 18x9.5 and 18x11s are perfect. i can go lower than this too.
https://static1.pt-content.com/images/pt/2013/03/IMAG0327-1.jpg
https://static1.pt-content.com/images/pt/2013/04/IMAG0325-1.jpg
https://static1.pt-content.com/images/pt/2013/04/IMAG0324-1.jpg

Beautiful car! My 67 has a Lateral Dynamics rear suspension and the DSE tubs/frame mod. I’ve been told the 67/68’s can only fit the 315’s most of the time.

What rear brake package are you running? Your total WMS to WMS is 70.3?

[Ron.in.SoCal]

alot of autocross guys are switching to a 315 for faster lap times. 335s tend to push. A 275/35/18 and 315/30/18 are pretty much the exact same height and with this rim and riire combo everything is spot on. from overall diameter, tire bulge, manufacture recommended tire to wheel specs.

If you really want to be safe get a 18x11.5. That way if you go with a 335/30/18 and it rubs some you can then switch to a 315 and it will still look great on the rim.

Your second paragraph is spot on Randy.

Although you make a good point, not sure I agree 100% with your very first sentance. Yes 335s will push, but the 315 switch I've seen are from guys wanting to run the Falkens which only came in that size; this switch did lead to faster lap times. Following that, now that the Rival is out I would not be surprised to see some switch back to 335s if they're able to fit them on existing rims/chassis.

The trend for the Autocrossers I know is to go bigger on the front to balance the car better and reduce understeer. Available traction for acceleration, turning and stopping begins at the tire contact patch. Bigger all around helps this.

Just my .02

[icemanrd19]

I need to call kore3 to get the rear parking brake but im running 2012 corvette z06 front and rear stock brakes. Honestly i could fit a 335 in there but im telling you it would have to be spot on and I feel like i could slam the car lower with a slightly skinner tire. Plus i feel that its the perfect balance front and rear.

We have a art morrison 69 camaro in the shop now. If you want i can go over there some time and get whatever measurements that you need.

[Cdog]

alot of autocross guys are switching to a 315 for faster lap times. 335s tend to push. A 275/35/18 and 315/30/18 are pretty much the exact same height and with this rim and riire combo everything is spot on. from overall diameter, tire bulge, manufacture recommended tire to wheel specs.

If you really want to be safe get a 18x11.5. That way if you go with a 335/30/18 and it rubs some you can then switch to a 315 and it will still look great on the rim.

Good call. When we ran the 67 in my sig at the RTTH events we were on stock wheel wells. Traction was iffy at best. My 67 is going full retard for these events and this 69 is going to be a driver that we can use until the 67 is done. I opted to build a 69 instead of buying a newer car to drive everyday. Can’t say if it will stay that way yet, but I got the wife to buy off on it for now. LOL!

[icemanrd19]

Trust me i wanted to go with a 335/30/18 at first because my cost on a set of bfg were dirt cheap. By switching to a 315/30/18 it ended up costing me about $500 more .

Being that he has a 69 335s will fit no problem. The main issue that i see is that people are doing all these great mods to fit a 335 in the rear and do nothing on the front so they are stuck with a 245 or 255 in the front.

[Cdog]

I need to call kore3 to get the rear parking brake but im running 2012 corvette z06 front and rear stock brakes. Honestly i could fit a 335 in there but im telling you it would have to be spot on and I feel like i could slam the car lower with a slightly skinner tire. Plus i feel that its the perfect balance front and rear.

We have a art morrison 69 camaro in the shop now. If you want i can go over there some time and get whatever measurements that you need.

Thank you. Any help would be appreciated. The guy’s over at AME are real slow to draw up an Invoice for me. I want to build the Ford 9 inch around 5-5.5 inch back spacing in a 18x11.5-12 wheel running a 335 tire.

[icemanrd19]

Call matts classic bowties. They shipped all the parts to the shop for the art morrision 69 convertible thats there now. I also bought all of my stuff from MCB.

[Cdog]

I wanted to update this thread. Some things have changed since last year when I ordered the AM Tri-4 link. We’ve decided to go full tilt on my 69 and make it a full Art Morrison chassis car. We at Starlite have recently became an Art Morrison dealer. I’ll be robbing the AM C6 front frame from my 67 to put on my 69. I’ve already got a replacement AM frame in process for my 67.

We’re going to stretch the front fenders on my 69 about 1.5 inches to squeeze more traction out of the front end. That being said do any of you know what tire and rim combo perform best in this situation to maximize traction and handling? We have a rim sponsor so backspacing can be dialed in. My guess is a 305-315/18 front and a 335/18 rear. The fronts will be ran on the smallest possible rim size to get them to fit with out rub. Inner wheel wells will be modded as well.

What are your thoughts?


We’re wrapping up some sponsor/relationship details on the car. As soon as the business end gets finished up I will be doing a build thread to get you guy’s up to speed. We’re looking forward to getting our Whip in the ring ASAP.

94910

[tomt12345]

Forgeline
Model GA3
size 18x11
offset 25.4
b.c. 5/4.75
hub 70.3
finish trans smoke
application camaro

DSE quadralink standard width. One thing i can tell you is that i want my car low and i felt with a 335/30/18 and a 12" wheel i wouldnt be able to really get it in the sweet spot. Hell i was even told that a 18x9.5 wouldnt fit without rubbing on a 67 with the dse front subframe. I took a chance by going with a 28.58 offset on the front and OMG its perfect. The 18x9.5 and 18x11s are perfect. i can go lower than this too.
https://static1.pt-content.com/images/pt/2013/03/IMAG0327-1.jpg
https://static1.pt-content.com/images/pt/2013/04/IMAG0325-1.jpg
https://static1.pt-content.com/images/pt/2013/04/IMAG0324-1.jpg

Iceman this is perfect. I am almost ready to order rims, just to be clear what are front and rear sizes and backspaces? As I understand it, you have mini tubs and stock rear end width just like me on my 67. I am being told 5.75 BS on my 18x10 fronts for some 275s with Ridetech True Turn and out back I considered and have measured 18x12 with 7.5 BS for some 315s. Maybe I dont need 10 and 12, I like he dish look on the back though. Yours is exactly what I am trying to get. Thanks!