Hi all,

I am almost finished installing a 450 hp. EFI 383 stroker into my 87 GTA. I would like to upgrade my Rear End assm. to handle the extra torque. Is it possible to upgrade the 9 bolt to handle up to, say, 700 hp ? I plan to add a supercharger eventually and would like to leave some room for power increases as I progress with my hobby car. Thanks everyone for a great site !

Rob in Edmonton Alberta

 

you have 2 choices really.

1. try it and if it breaks buy a 9" from moser, strange, etc

2. sell it for a couple hundred and put that towards 9" rear end.

 

Thanks, I was hoping to keep it stock looking and if the consenses is that it will likely break, than I would prefer to upgrade now. I have 3 sons that will be riding with me to local car shows and consider safety and reliability my first priority. I am not a drag racer but we have some stop lights here on our four lane highways that allow some "spirited accelleration". Is there enough upgrades for the "aussie posi " to allow it to handle the 500 ft/lbs my current engine will be producing at the flywheel? It has a TCI super streetfighter 700R4 and a custom 800 hp rated aluminum driveshaft and my next mission is to build a solid rear end assembly. I searched and didnt find too much about strengthening the 9 bolt posi unit that is in the GTA's and IROC's. Perhaps someone knows of some threads that deal with these questions ?

Thanks

 

I dynoed 424 FWTQ which puts that over 500 at the fly and my 90K 9 bolt is living fine on just a fluid change.

 

on the street you won't hook enough to break the 9 bolt on street tires so i wouldn't worry about it. I have a 9 bolt under my car and it's withstood decent 60' times without problem, but next winter a 9" is going under my camaro.

 

Wow thats great news! I have read and heard many conflicting views regarding the 9 bolt. I have heard it described as the weakest point of the drivetrain and also as a stronger alternative to the 12 bolt....? Does anyone know where to purchase a fully built complete rear end assembly utilizing the 9 bolt housing with a 3.73 posi ,good axles, ect....or is it the housing itself that is the weak point. Perhaps there is a vender here that can supply a complete bolt in rear end that I could swap in or maybe a complete parts kit with everything I need to have a profesional shop build up mine. Is there any companies that sell a complete 9inch ford with provision for rear disc Baer brakes and will hook up to a spohn torque arm. I also considered a chrome 4 link from Airride technologies and a complete airride suspension. I assume if I go with this system than I could use any performance aftermarket rear if the width is correct. Any thoughts on the air suspension with four-link option compared to a conventional coil spring/gas shock system on these cars? I am trying to build a powerful,reliable G-machine out of this car and would love to hear some suggestions for a great handling package that will take the power of a (eventually) supercharged smallblock.

The car so far :

-mint exterior and interior 87 gunmetal GTA
- 383 with balanced R/A (all forged) 9.7-1 ,AFR 195's Crane gold 1.6 rockers, Comp beehive springs, Hooker super comp 1.75 headers
-Edelbrock pro-flo 1000 cfm sequential EFI induction system
- Edelbrock 7102 cam
- Estimated FWtorque 500lb/ft FWHP 450

TCI super streetfighter with 2400 stall
HD aluminum driveshaft
hotchkiss weld in sfc's
Baer track front brakes
C5 17" wheels

Undecided on rear end so-far but feel a little uneasy about staying with the stock piece. The rear end selection will allow me to determine the suspension system that will be installed.

Again, I would love to hear some ideas on finishing this build to create a top performer in auto cross and the odd stoplight war ! Cost is not as important as performance on this car.

Thanks for the input so far guys !

 

no sense in building up the 9 bolt at all, you're better off using the stock rear end or selling and upgrading to a $2500 aftermarket 9" with whatever you want for gears, posi, lockers, brakes, etc. I wouldn't spend $900 on a 9 bolt to get gears, etc when that's almost halfway to a 9"


Furthermore, a 4 link involves backhalving a thirdgen and is very time consuming and expensive. A few members have air rides, but I wouldn't consider them G-machines, most are for show.

 

Thanks, I really appreciate the input. Is there a source for a turnkey 9" that will bolt right in to the 3rd gen including torque arm mounting provision and spring perches LCA mounts ect ? I guess 4 link is out for me since I have no desire to back half this car ! I have read some articles about the Airride Technologies systems and they are claiming a substancial handling improvment as well as a better ride. I dont want a car that jumps up and down or "lays frame" . I would like to lower it an inch or two for handling and get the bonus ride improvement. I know this is the drivetrain forum but the rear-end I purchase will need to integrate with the new suspension. What do you suggest for suspension when combined with the 9 inch rear . I am considering adjustable LCA,s ,torque arm, QA1 shocks, urethane bushings, and a stronger rear sway bar. Of course the front suspension will be matched to the new rear and I will post in the proper forum about that. I just want to be sure to order the correct rear end to fit with the suspension mods that you experts suggest here.

Any estimates for horsepower ratings on a custom 9" and also a strengthened 9 bolt ?

Thanks

 

moser, strange, and currie all make bolt in rear end assemblies. they can be found through google. custom 9" can handle any power you throw at it, discuss with the manufacturer how many splines, etc.

 

a 9" can be built to handle anything you're ever gonna throw at it. ^ the above info is correct, Moser, Strange, Currie, and a couple others. Personally I'd go that route long before going through the head-aches of locating 9-bolt parts, especailly since the only "upgrade" available is the TA girdle(cover).
- as for the suspension, the factory lay-out works very well for handling and for strip launches, but it needs better components to do it. Subframe connectors, lcas, a torque arm, and lca relocates are great. Adjustable shocks are deffinitely nice/helpful.

 

Yes and I have sent a fax to my local speed shops for a price quote on a 3.73 Strange 9" and a Moser 9" to handle a potential of 700hp. I am perplexed at the lack of info on the Airride Technologies system. I would love to attach the new 9" to one of these systems that the company and magazines say are great. The ride is supposed to be like a luxury car and the handling compares with the best handling mods available. 2 inches lower than stock but can be raised up with the push of a button to clear speed bumps and sharp driveways. The reveiws I have read rate this setup very highly but I have far more trust in the true experts that own and love these cars as much as I do. I bought my Hooker long tubes before I read the stellar articles written by members here and probably would have stayed with shortys once I saw how involved the rest of the install was ! I have no problem dropping 4 large on this suspension if there are some members here that have positive experiance with this set-up. OTOH I guess if someone has to be the pioneer on this deal than I will ante up and try it out. I sure would love some input if it's been done on a third gen ! I just got my first quote for the 9"- 3779.00CAD. with auborn posi and 31 spline axles ! I have to use my own backing plates and install the axles myself. If they are all that high than the girdle( cover) may be the answer until pro-charger time ! Airride?

Thanks everyone( Pictures of GTA soon)

 

yes, compared to a leaf spring suspension of a 68 camaro or the older link set-ups like the chevelles, etc, the air-ride set-up is wonders. - I can't see it out handling/performing our factory set-up(with aftermarket components). The air ride itself can be nice for ride with performance, but not really better handling/performing than proper coil springs and shocks.
- you might want to look more into magazine adds an such for the rear. Most performance shops I know of charge and arm and a leg more than what you can buy it for.