Upgrading to another axle would be such a hassle and expense. How much power do you suppose a standard open 2.73 or 3.08 in a G body could handle? Just using the standard 70 series road tires and the occasional (ok, maybe more than occasional) :Brow: peg-leg burnout? Perhaps enough for a mild Buick 350? ray: Or will I have to get some upgrades? I figure on getting at least a TA girdle and maybe some studs. Danke schn!
Your best bet is to take some steps to make that rear end live. The main weak points of the 7.5 is the carrier and axles from what I understand. http://www.summitracing.com/parts/dtl-912a317/overview/- carrier http://www.summitracing.com/parts/msr-a102810/overview/make/buick/model/regal/year/1987- axles http://www.summitracing.com/parts/msr-9200/overview/- c clip eliminator http://www.taperformance.com/proddetail.asp?prod=TA_1809- rear girdle On top of this it is recommended you have the axle tubes tacked in for extra insurance. So when you add it all up, its about as much as it would cost for an 8.5 Sure you can take it easy on an open 7.5 rear but there are no guarantees it will hold up for the occasional holeshots. With it not being posi you risk damaging the rear if you do extended high rpm burnouts. If it was posi, or even if you end up getting it to hook you will almost certainly blow a stock 7.5 with 400lbft of torque. I say save the money an try and find an 8.5. That or look for a used posi carrier for the 7.5 (26 spline unless you want to buy axles too) and just tack the tubes and throw a girdle on. or there is this route... http://www.theturboforums.com/threads/326689-My-G-Body-8-8-Rear-End-swap-complete-w-pics
Thanks Jacob. :TU: Though I have heard that the ford 8.8 isn't much stronger than their 7.5's. Ford 7.5 must be stronger than the GM 7.5 Plus even if the swap costs the same as an upgraded 7.5, you're still saving the trouble of the extra fabrication and fitting. I suppose whatever works, someone could just go the route they prefer, as long as each setup holds.
I would say the Ford 8.8 is about on par with a GM 8.2 rear. In a light car like a regal or mustang it should have no problem handling the power you will be making in stock form. Not to mention the fact that parts are very cheap. A posi rear could probably be had for around $400 I have a friend that has a strong 351w in his 59 f-350 and he puts almost 450hp through an 8.8" and that is in a 4500lb truck. It may cost the same as an 8.5 swap or building a 7.5 but the happy consequence is the money spent to make it fit means you end up with fully adjustable rear suspension. Something that will make the car a lot more fun to drive. Nothing is worse than having a bunch of power and then wheel-hopping your brains out every time you go for the skinny pedal http://www.carcraft.com/techarticles/116_ford_8_8_rear_end/viewall.html
The 8.8 is more on par with the GM 12 bolt. Tons easier to find in the yards too. The 95-01 Explorer has rear disc brakes too. The Explorer (and Mountaineer) axles are 31 spline. The 99&up Ranger with the 4.0L V6 also has the 31 spline 8.8. The 4 cyl. and 3.0L version are only 7.5". Most car axles are 28 spline....eventually, they finally put 31 spline in the Mustangs(mid 90's or so).
Thanks fellas. What sort of headache would it be if I found a GM 8.5 and swapped the entire axles out? What lines up and what doesn't? Will the driveshaft need cutting too?
You are right, the main weak point of the 8.8 is the small axles, so if you go to 31 spline it would be practically indestructible. For a 400lbft goal I think the 28 spline axles should be more than adequate
Ford actually used the same 1.625" front pinion support on the 8.8 as the GM car 12 bolt. The truck 12 bolt is actually a lot weaker. The Explorer disc brake rear measures 59 3/4" WMS to WMS, so it should fit in quite a few applications.
LOL. funny stuff The only rear that will exact interchange and was a factory rear is the 1984-1987 442 and Grand National rear. This rear is 8.5 ring gear same pinion size as a 12 bolt chevy and 8.8 ford. Axle spline count is 28 and is c-clip (weak case hardened stock axles) ALL 8.5 10 bolts require a drive shaft shortening with a swap of any GM rear (7.5 12 bolt chevy 8.2 chevy or 8.2 BOP rear. ) FINDING THIS REAR IS THE DIFFICULT PART...AND IN GOOD CONDITION AFTER BEING IN A HIGH POWER GN IT MIGHT BE PRETTY WARN... We build 8.8 for rears and they are stronger than the 9" Ford. (yah, yah I know your going to fight me on this one BUT we are talking stock to stock 8.8 will win every time. ) STOCK FORM 8.8 with a mini spool we have run 9.90 in cars. I know that is SICK...AND NOT RECOMMENDED by any means. Stock 9" has alot of weak spots pinion support cast too thin, bolts that hold the pinion support in, casting the bolts are screwed into are too out board on the housing and rip through. Pinion support bearings too small and close together. Pinion end supports are always fracturing. Shall we go on? Anyway lets talk about what you can do. ALL those upgrades listed from summit are great BUT... How long will you stay at the 350 low horse engine ? If you think you are going to stay at that level for the rest of the time of your life and your keeping the car ...YES spend the money on the 7.5 it will be fine. IF you are planning a upgrade with more torque and power than 400 HP in the near future with in 5 years. THINK AHEAD and spend the money on a bigger rear that will hold. Looks like at the very least 1000.00 (oh and the 8.5 does not come with c-clip elim from GM ) YOU HAVE REMEMBER AND know WHAT THE WEAK SPOTS ARE IN ANY REAR. 1.) number one weakest point are the spider gears of any rear. They have to take all the torque and deliver it the the wheels and weight of the car and torque stress. 2.) Next the axle shafts being made from inferior metal and smaller under sized shaft size behind the axle spline. C-clips really are not a problem unless the axle BREAKS. So install a good alloy axle and then you do not need to worry about this. If you run 11.50 and faster at the track then you need to worry and only IF you are running on a NHRA or IHRA sanctioned race NIGHT . Remember most car we are talking about here are street bound cars NOT every weekend bracket race cars. 3.) stock ring and pinion gears - again material inferior for heat and punishing burn outs and hard launches. I build 8.8 ford center G-body custom rears and 10 bolt 8.5 Gm center g-body custom rears and even 12 bolt chevy center g-body custom rears. ALL are exact same width as your 7.5 10 bolt g-body width, we sell the upper double adjustable control arms that install these rears as a direct bolt in rear. Some example pictures for you. 1500.00 range. Seems pricey BUT if you look at what your spending on the 7.5 and not being able to find 10 bolt 8.5 GN / 442 rears AND the biggest thing the axles are 30 spline NOT the small 28 the GN has. It is a big deal. This is a tough car rear as there are not any good GM alternatives unlike the 1965-1972 era and 1973-1977 era.
:gp: Jim is the definitive authority when it comes to this subject, all I was doing was ballparking I spent some time reading up on the 8.8 and it truly is impressive the bang for the buck you get.
Got a buddy running 8.40s with an 8.8 and we got a vega with a 7.5 and its 3rd pass at 11.60s broke the left axle and put te tire into the wall. Just something the think about. That vega is light and has about 425 at the tires without nitrous an was off the spray.
Thanks everyone for the great information, I really appreciate it! Looks to me like as long as I stick with the mild 350 the beefed up 7.5 would do the trick, but if I ever wanted to go more radical with it, I'd have to upgrade. I doubt I'd ever upgrade to more power in this car, and if I ever did want to, I'd just get another car and go with the $1500 8.8 there. This car will make around 400-425 ft. lbs. at the flywheel, so it wouldn't even come close to that at the wheels. Plus I don't plan on drag racing it or putting slicks on it. Standard 225r70/15's is probably what it will have on it at the biggest, most likely though 215r70/14's in all likelyhood. Small street tires and no stahl converter and auto trans. My plan is to have fun in the car, cruise and get good mileage, and burn rubber when I feel like it--I actually WANT it to spin the tires without power braking. ---UNLESS...I get a wild hair and do the crazy shyt I used to do when I was 22...then I'll be needing one of those 8.8's lol... I had a '68 4300+ lb. Lesabre with a 350, st300, and 2.93 open axle (not sure if it was 8.2 or 8.5) that I would abuse on a daily basis. Neutral drops were the order of the day, as well as full throttle reverse to drive shifts. Never broke anything in the time I had it, though I did eventually blow up the 350. Now that's saying something for the st300 and axle! anyway...I think the hardest thing on the drivetrain is the hard, no-tire spinning launches with stahls at peak torque. Tends to cause the parts to flex beyond the breaking point. If the tires won't spin, something's gotta give! If I do get an axle though, it looks like it'll be that 8.8--but only if I went to nitros or forced induction or a big block. This car will keep its engine as long as it can. If I want a drag car, I'll buy a car for that and get the 8.8. Thanks for all the useful info! ---------- Post added at 10:50 PM ---------- Previous post was at 10:12 PM ---------- Bah, heck with it. I've never regretted getting good stuff. (My toolbox full of Snap-On tools is a testament to that) I'll let you know when I'm ready for that upgrade. ---------- Post added at 10:53 PM ---------- Previous post was at 10:50 PM ---------- ou:
2.73 3.08 3.27 3.31 3.55 3.73 4.10 4.56 4.88 etc. Pretty ok. 8.5 has a wider range at 2.41 2.73 2.93 3.08 3.23 3.42 3.73 3.90 4.10 4.30 4.56 4.88 5.13 5.38 5.57 7.5 IF you need some pricing on the 7.5 parts we always get deals from buy outs on other peoples parts ...Give a PM or call and will see what I can whip up . JIm
monzaz is definitely reigning authority on rear axles. I beat on my 7.5" for several months behind a stock'ish low compression 455 with a 5-speed behind it. It's probably in the ~320HP range, unknown torque. I did worry about it though and eventually changed it out for an 8.5". http://www.youtube.com/watch?v=R_CCLSwdLhU
Heh. A bone stock 455 low compression is rated at 450 ft. lbs. at the flywheel, which is more than I'll have. Torque is what kills an axle. And the one you have is stock'ish' meaning even more power, is in front of a manual tranny, and by the sound of it, you didn't take it easy on it--for at least several months. The 7.5 sounds like it'll hold up to a mild 350 to me! Especially with better carrier, ring and pinion, new axles and welding up the tubes. I think the biggest thing here is sticky tires and launching with stahls at close to peak torque, sticky tires being the number one reason. If you put that much strain on it and the tires won't give, the axles or gears will. ---------- Post added at 03:12 PM ---------- Previous post was at 03:05 PM ---------- Thanks Jim, you've been a big help. Somewhere around 3.55 is my goal. Was just wondering which ratios Ford offered. I'm pretty much in the know on GM stuff. If I decide to keep the 7.5, I've been shown some parts at Summit, and I see a nice steel carrier made by Eaton and is a Detroit Locker, using Truetrac. I did a little research on the truetrac setup, and I looks very attractive to me. I assume a similar carrier could be had in an 8.8.
From what I've gathered the GM engineering thought at the time going into the 80's and eventually the 90's was the tires will always break loose before the rear end meets it's breaking point. That of course assumes street tires. GM switched to the 7.5" in F-bodies all through the 90's. I don't know if those 7.5" parts interchange with your 7.5" parts. That'd be a good question for monzaz to make sure the summit parts bolt to your rear axle. By stock'ish I mean, a stock '72 engine that was bored .040" over with 8.5:1 pistons, an isky .454" lift, small duration cam, iron intake, iron heads, iron exhaust manifolds, and as seen in the video piped through a single 2" glass pack, yes, single 2" exhaust. The rear end was the stock '77 7.5" with 3.23 gears. As far I know it hadn't been opened and certainly didn't have any aftermarket goodies on it.
So basically a stock 455 bored to 464 cubes (which would give a few more ft. lbs.) and a bigger than stock torque oriented cam. I bet that engine produced no less than 475 ft. lbs. then. Plus you had a manual trans, which puts more jolting strain on the drivetrain. Seems the 7.5's main issue is warping and twisting--which would actually help absorb some of the shock and make it LESS likely to break under those strains, BUT, if the tires won't give, it flexes past where it can absorb and breaks. So as long as you don't have hot n sticky meats or overly big street tires, I see no reason why it wouldn't hold up, particularly if you put better guts in it. Edit: Just watched your video. That's the kind of thing I was talking about in my origonal post, the 'peg leg' burnouts. Those would put the least strain on the axle, I would think. BTW you can really hear that back pressure with that 2" single tube lol.
The sticky tires or harsh down shifts at speed are what concerned me the most. The small glass pack exhaust pictured is what was on the car. I'm sure it had all sorts of back pressure, lol.
