67 Barracuda project... narrowing 8 3/4 rearend

[Brandt Fonda]

Hoping to get some opinions on best way forward with my 67 Barracuda project. The car was a Commando v8 4bbl car, now it is a 360cid Holley sniper EFI car. I am going resto mod with the car so am not concerned with oem parts but also don't want to wind up in a geometrical nightmare. I am looking to have a drivetrain and rear end capable of holding 650 crank HP. I currently have an 8 3/4 rear end with a 489 third member. I am trying to decide between rebuilding and narrowing the 8 3/4 or going with a 9" ford setup (also narrowed). I was thinking about going about 2 inch narrower (give me 1 inch on each side correct?) and installing the QA1 6 link rear suspension. What issues will I encounter with narrowing either, as far as fitment? Is it very technical to setup and fit the 9 inch into an A body mopar? (And what will I need to be considering for axle shafts, rotors etc? Thanks! edit: am considering 4.11 rear gears and tremec tko 5 speed 2.66 first.

 

[scott657]

on the 9" you may only need to shorten 1 side this will center the pumpkin, but leave the drive shaft a little offset, Then just get 1 axle. I think curry has an axle with about 10 inches of spline, you cut to length.

 

[Boedighw]

Yeah, I was taught to have the center of the pumpkin offset. The U-Joint works best when it has a little bit of angle. This is counter intuitive to what you would normally think.

Are you tied to the QA1 Rear End? For the money, I would invest in the RMS Street Lynx. Either of these kits will require the spring perches to be in the same place as the factory rear end.

Paul Horton Welder Series is a Canadian company that makes all the brackets you would need to install the 4 Link yourself.

Last, I would recommend the Ford 9in because of all the aftermarket support. It seems like you are ready to spend some money on this project and you are not trying to keep it original. I think 650 hp is the limit of the 8-3/4", and might be into Dana 60 territory.

 

[Brandt Fonda]

Thank you guys for your replies, I measured my housing and it seems to be a little over 52 inches (think A body width should be 52 5/8"). So if I do go with the 9" should I shorten the driver side by the 2"? Are there any shops or mopar guys out there that provide turn key narrowed ford 9" setups for our A body cars?

I'm not married to the QA1 I just heard they were a good quality product. I do plan on spending money on this project but of course don't want to spend in the wrong direction and I do have a budget. I'll probably have to do this in stages, right now I'd like to tie up the drivetrain and not have to revisit it later on. I was looking at FRESH BUILT NASCAR DODGE MOPAR R5 P7 WET SUMP ENGINE pump gas 745HP 540 ft-lb torque for the engine. My ultimate vision for the car is a corvette eater both on the track and in the curves lol. (Top end is not important to me). Track days are important but I want to keep the manual trans for the fun factor on the street and for cruises. I live 30 minutes from Deals Gap US 129 so handling will be very important. The next portion of my build of course will be the front end so any input on that will be greatly appreciated, up til now I had planned on the QA1 suspension for that with the flaming river steering column and manual steering box.

 

[john-9]

Hoping to get some opinions on best way forward with my 67 Barracuda project. The car was a Commando v8 4bbl car, now it is a 360cid Holley sniper EFI car. I am going resto mod with the car so am not concerned with oem parts but also don't want to wind up in a geometrical nightmare. I am looking to have a drivetrain and rear end capable of holding 650 crank HP. I currently have an 8 3/4 rear end with a 489 third member. I am trying to decide between rebuilding and narrowing the 8 3/4 or going with a 9" ford setup (also narrowed). I was thinking about going about 2 inch narrower (give me 1 inch on each side correct?) and installing the QA1 6 link rear suspension. What issues will I encounter with narrowing either, as far as fitment? Is it very technical to setup and fit the 9 inch into an A body mopar? (And what will I need to be considering for axle shafts, rotors etc? Thanks! edit: am considering 4.11 rear gears and tremec tko 5 speed 2.66 first.

go with the 9 inch Ford ,, like stated parts readily available and easy to switch center sections -- now determine what you need for the actual overall width of the rear axle and gear ratio,, brakes being used , mounts and brackets etc.---
Call Moser Engineering ,,an excellent company to deal with --- tell them which car you have and then give them all the details of what you need -- i would go with 35 spline axles ,1350 pinion yoke and a Detroit Locker which is available for 35 spline axles ( makes street use possible )
they will build you an exact axle that will bolt right into your car .

 

[Brandt Fonda]

I had hoped to save some on the axle so I could go forward with suspension and transmission at the same time, Moser was my first choice but is very pricey. If I did go with moser should I consider the Dana 60 or 12 bolt? I was looking at: Ford 9" inch nascar rear end housings , chun for sale in SPARTA, TN, Price: $135 but of course I'm going to have to do a lot of research and build it myself (part of the fun!). Though I do know I will need an experienced person to set up the differential.

 

[john-9]

I had hoped to save some on the axle so I could go forward with suspension and transmission at the same time, Moser was my first choice but is very pricey. If I did go with moser should I consider the Dana 60 or 12 bolt? I was looking at: Ford 9" inch nascar rear end housings , chun for sale in SPARTA, TN, Price: $135 but of course I'm going to have to do a lot of research and build it myself (part of the fun!). Though I do know I will need an experienced person to set up the differential.

pricey -- not really --- your engine 650 hp , tranny Tremec ,, both pricey items but you want to save a few dollars and not make it around the track ,, let alone finish any event you enter ????? ---- do it once but do it right.
stay away from the Nascar housings ,, cheap yes ,,, but the housings are aligned to fit the car and track they will be used at .not too street friendly.


Dana 60 gear changes take time and gear ratio selection very limited ,, 12 bolt same issue and weaker ,,, 9 inch Ford best bang for the $$$$ spent. lots of gear ratios available from 2.50 -7.50 and readily available along with any parts you may need for it .

 

[Brandt Fonda]

Good point, it would be even more pricey if had to redo the rear because of failure. Thank you for your insight. What is your opinion on narrowing? I have right at an inch till tire contact with leaf springs (QA1 suspension will replace the leafs which should give me a little more room) will I be able to get enough tire under the car without narrowing? tank, shocks, and my 3" exhaust are taking up a lot of real estate!

 

[john-9]

Good point, it would be even more pricey if had to redo the rear because of failure. Thank you for your insight. What is your opinion on narrowing? I have right at an inch till tire contact with leaf springs (QA1 suspension will replace the leafs which should give me a little more room) will I be able to get enough tire under the car without narrowing? tank, shocks, and my 3" exhaust are taking up a lot of real estate!

narrowing slightly should not be a problem -- but i would first determine which tire size you are going to use along with the size and back spacing of the rim
once you have the rims and tires, i would drop the rear axle , springs , shocks leaving the gas tank in place
place both the tires into the wheel wells , leaving clearance you need at the outer lip (3/4 to 1 inch ,,, check the inside of your wheel tub for clearance as well as the clearance to the gas tank
now measure the distance you have between the 2 wheel mounting surfaces of the rims and this will give you the overall width of the rear axle needed
leaving the tires in place you should be able to locate where your rear suspension will be hung , if not , mock up the original axle with some templates of your suspension brackets etc. ,,,place the axle on jack stands under the car and work from there.