Looking for rear end opinions

[1985olds]

The car is a 1985 cutlass. Turbo 5.3 making about 500-550 whp through a t56 magnum. Carbis used for a daily on nice days and autocross. I have an 8.8 that I can build to make a stout rear with Ford 9 inch ends to eliminate the c-clips and the necessary instant center correction kit for about $1900. The other option is a quick performance bolt in 9 inch for about $2200-2300. I worry about the added weight and parasitic loss of the 9 inch and the rear geometry issues with the 8.8. Looking for opinions on which one you would pick? Thank you.

[CSG]

I have made WAY more than that and used 8.8's. What geometry issues are you referring to? Trying to use the factory tabs and upper mounts?

[1985olds]

I have made WAY more than that and used 8.8's. What geometry issues are you referring to? Trying to use the factory tabs and upper mounts?


Yes, the upper mounts, I'm not worried about the strength aspect of it. I'm just wondering if the hassle to make the 8.8 work is worth the decreased weight, parasitic loss and expense of the 9 inch

[CSG]

For me I would chose proper geometry. I will spend hours in cad fine tuning suspension designs though so I can tend to get too wrapped up in trying to make something "perfect".

[parsonsj]

I'd use the 8.8, and Ford gears. The 9" with aftermarket gears will be noisy -- with a special whine right at cruising speed. :(

[andrewb70]

Does anyone make a 8.8 rear that has the right "ears" for the upper control arms on a A-body?

Andrew

[parsonsj]

I'm sure I can. :)

[CSG]

What you want is a low profile link between the two ears. That way you can mount a 3 link!

All the 8.8's that i am aware of have the same ears or none like the explorer. I do like the 3 link though if you are interested in going that far. I did that on a fox coupe and it worked well.

[130fe]

I have a Quick performance 9 inch center section in my 68. Whiney gear noise at 40 mph and up. I would use the 8.8 if you are able to fab the pieces to put it in.

John, are factory 3.90 9 inch gears still available?

[CSG]

1985Olds, I received your PM. I decided to reply here so others can join the discussion, always best to get more brains involved.

I see that you have 3 options if you wish to run a 8.8.
(1) modify the housing to re-locate the ears
(2) fab brackets to relocate the ears
(3) use a type of 3-link

If you choose option 1 or 2 then the first thing you have to do is figure out where the ears need to be. This may eliminate one of the options due to physical limitations. For option 2 look into the systems like this: http://www.baselinesuspensions.com/kits/outlaw.htm for ideas.

If you choose option 3 then you have two common choices. A torque Arm or the short upper single arm type. I have ran both and have no complaints about either. For me personally I would consider purchasing a Maximum Motorsports torque arm for a mustang and modifying the crossmember to fit your car. Obviously you would still need something for lateral location so you would need to fab a panhard bar. I say this option for the ease of fabrication and it is a quality piece. The short upper option will require 100% new components, so a lot more work involved. Look at the old EVM 3-link for examples of this type setup.

[SSLOW6.0]

1985Olds, I received your PM. I decided to reply here so others can join the discussion, always best to get more brains involved.

I see that you have 3 options if you wish to run a 8.8.
(1) modify the housing to re-locate the ears
(2) fab brackets to relocate the ears
(3) use a type of 3-link

If you choose option 1 or 2 then the first thing you have to do is figure out where the ears need to be. This may eliminate one of the options due to physical limitations. For option 2 look into the systems like this: http://www.baselinesuspensions.com/kits/outlaw.htm for ideas.

If you choose option 3 then you have two common choices. A torque Arm or the short upper single arm type. I have ran both and have no complaints about either. For me personally I would consider purchasing a Maximum Motorsports torque arm for a mustang and modifying the crossmember to fit your car. Obviously you would still need something for lateral location so you would need to fab a panhard bar. I say this option for the ease of fabrication and it is a quality piece. The short upper option will require 100% new components, so a lot more work involved. Look at the old EVM 3-link for examples of this type setup.

Dont forget the S197 Mustang came with a 3 link setup from the factory. If you're going to go through the trouble of cutting down an 8.8, with ford 9 ends, and custom axles, that may be the way to go. You can add a panhard rod and be good to go. This may be the route I on my 86 Monte SS.

[CSG]

Man, I am slipping. I forgot about those and I even built one!

[CSG]

Another option would be a 4-link built like the Steeda 5-link. Mount the upper arms on the tubes and run a panhard bar. Those system worked really well. Less bin due to less angle in the uppers and would be pretty easy to build.

[parsonsj]

Dont forget the S197 Mustang came with a 3 link setup from the factory. If you're going to go through the trouble of cutting down an 8.8, with ford 9 ends, and custom axles, that may be the way to go.That's the best way. Those housings have 3" axle tubes. Cut off the ends, machine off the center casting link, and weld the resulting hole closed. Then put on SET20 ends, new Ford gears, the diff of your choice, and 31 spline axles. I've found that setup to work really well with DSE's Q-link. Adding brackets for a GM angled 4 link should work really well too.

[parsonsj]

John, are factory 3.90 9 inch gears still available? Sorry Chris, Ford hasn't made new 9" stuff for a very long time.

[130fe]

That’s what I figured John lol

[1985olds]

Thanks guys for all of the responses. Looks like I'm going to put the 8.8 in with the instant center correction kit so the car will be ready for power tour and try a 3 link setup next winter when hopefully I have time to mess with it. Merry Christmas to everyone as well.

[1985olds]

So I've been collecting 8.8 parts and looks like it's going to cost about the same as the 9 inch. Is the general consensus still in favor of 8.8?

[parsonsj]

That's what I'd do. I know we have testimony of Ernie from Texas being able to make a 9" quiet, but every Tom, Dick, and Harry can do that with an 8.8 using Ford ring and pinions.

[1985olds]

That's what I'd do. I know we have testimony of Ernie from Texas being able to make a 9" quiet, but every Tom, Dick, and Harry can do that with an 8.8 using Ford ring and pinions.

Thank you. Have you ever done an 8.8 in a g body?

[parsonsj]

Have you ever done an 8.8 in a g body? Does almost count? Sorry -- I was talking with somebody about doing one, but he ended up going with used parts; I don't know how it turned out. I've done a few with DSE Q-Links, which is quite similar. You'd need to find custom brackets to weld to the housing for the links.

[1985olds]

I was going to use this kit

https://trickchassis.com/index.php?id_category=55&controller=category

I just worry this is a band aid and not a solution.

[1985olds]

Has anyone used this kit or have any issues with it?

[BonzoHansen]

OK so dumb question of the day why use an 8.8 and not find factory 8.5 housing and build that? You can build a pretty stout 85.

[parsonsj]

I like the 8.8 because you can get everything you need brand new from Ford. I'm not sure that's possible with an 8.5, but I am prepared to learn something. :)

[1985olds]

OK so dumb question of the day why use an 8.8 and not find factory 8.5 housing and build that? You can build a pretty stout 85.

8.8 is said to be strong than the 8.5, though in sure some will disagree. With the 8.8 i can use Ford 9" ends and axles so I don't have to worry about losing an axle. I paid $100 for a fox body 8.8 vs. a stock 8.5 which range from $1000-1500. I'll only be a few hundred more into an 8.8 with aftermarket axles, diff, gears, new bearings and gaskets, labor of setup and supporting install parts

[CSG]

The Ford 8.8 is quite strong with good axles. Good brakes are easy to find and cheap. 9" end conversions are an affordable upgrade.

[BonzoHansen]

8.8 is said to be strong than the 8.5, though in sure some will disagree. With the 8.8 i can use Ford 9" ends and axles so I don't have to worry about losing an axle. I paid $100 for a fox body 8.8 vs. a stock 8.5 which range from $1000-1500. I'll only be a few hundred more into an 8.8 with aftermarket axles, diff, gears, new bearings and gaskets, labor of setup and supporting install parts
I didn't realize g body 8.5s were that much. F body housings are like $100. So yea that makes a lot of sense.

[Ben@SpeedTech]

Hey 85olds- I had the same question, I had a 325 hp/ 400 ft lbs sbc 406 and was lucky enough to find a stock GN 3.42 8.5" to put in my Cutlass wagon. Now I'm installing a new roughly 550 hp/ 525 ft lb sbc 406 and although I've read a 10 bolt can handle 500 hp ok I don't want to take any chances. I thought about the 8.8 swap and some guys on G-body forums have said it's relatively easy. Cost isn't bad since for a Pro-Tour build you'll be buying new rear control arms anyway. I think UMI has offset uppers for the 8.8 conversion and the lowers are supposed to be a bolt-in with any G-body arms.

After doing a bunch of research, I ended up choosing a 9" instead, I think the advantages out weigh the disadvantages. I found a trac loc rear in a '78 Bronco in the wrecking yard for $125. It's a lot longer than a G-body rear so I have to narrow it and buy new axles and may change the gears but even with that I'm still cheaper than ordering a new rear. Best I can tell is many Ford truck 9"s come with 3.50 gears, just about perfect for a P-T build, and they have the larger bearings and 31 spline axles. Factory gears will whine less than aftermarket.

The parasitic loss- Would I really miss a few hp on the street or autoX? No. Maybe if I were drag racing and trying to get another 1/2 of a 10th out of it but you'll never see that level of power loss factor in while autoXing. You can knock .005 seconds off your autoX time by saving a little hp loss, or simply become a better driver and knock 2 full seconds off your time. Make sense?

The extra weight- How much heavier is it anyway? I've heard 9" are lighter than 12 bolts but I can't confirm that from personal experience. I can't help but think a 9" isn't that much heavier than an 8.8. A car with 50-50 weight bias is a good thing for handling, so adding a few lbs out back may help with that anyway. From my observance G-bodies with pro touring suspensions like to lean towards oversteer until you get it tuned out, plus you've got a good amount of power so a few extra lbs over the rear tires to help with traction may not hurt either.

Strength- It should be safe to say the 9" is stronger, so if I decide a 150 shot of the bottle or a 700+ hp boosted LS may be in the car down the road I don't have to swap rears again.

Versatiliy- I plan to drag race my car with slicks on occasion (here's where the 150 shot comes in). I can grab another 9" center from the junkyard, install a mini spool and 4.56 gears and in an hour I have a drag race rear swap. Brake options for a 9" are wide open and super common, from 11" drums to 14" 6 piston discs.

Adjustability- I bought my control arm brackets from Speedway Motors which gives me several mount holes for lower arm adjustability and the top ears will be welded on in stock G-Body locations. I think you can get these multi hole brackets from any good axle builder if you buy a complete new housing. Since my car is already set up I can keep my Speedtech Articulink control arms that I'm very fond of.

Fit- You mentioned welding new ends on, which means you can narrow a Mustang rear, but if you were to use the Mustang rear "as is" like most swaps have been you have to use high offset wheels. G-bodies look good with deep wheels, so with the 9" I can have any offset I want. My current wheels have 4.5" deep lip, I like this much better than the Corvette offset look on the rear of old cars.

Cost- As mentioned with the Bronco axle I'll come out ahead of buying a complete new rear. A new pre-fab 9" is a bit more spendy. In the scheme of things the extra $ might be worth the extra insurance of having the confidence in knowing it'll probably never break despite any abuse you throw at it. You're already doing all the same work to the 8.8 to bring it up to 9" axle, end, brake etc. standards, why not just get the 9" and be done?

Look- I suppose there's some cool factor when people look under the car and see a 9". Everyone will know your car is serious and just saying it's a 9" conversion adds resale value to the car. The 8.8 will blend in and to the untrained eye they may think it's just a GM rear.

Hope this gives you some things to think about so you can weigh the options and make the best decision for you and your budget. Good luck with the build!

[1985olds]

Thank you for the response. You have me reevaluating my plans once again. You bring up a lot of good points. You said you picked up a bronco rear, will that center section housing stand up to the abuse? From what I found during my research the stock center housing is only good to about 425-450. If that is not the case that would make my decision easier. The major expense is not the rear end housing itself but the center section. A fab rear housing with axles/bearings from quick performance is only about $950. As far as brakes going I will be sticking with my 1995 corvette brakes as the parking brake is already set up and I like the performance out of them.

[Ben@SpeedTech]

Hmmm, I've never run across that hp limitation but will research it more too to be safe. What have you come up with for the 8.8's limitation? Aftermarket centers can get real spendy. If the factory 9 won't handle the power, then maybe the 8.8 is the best route for a budget build, the 9 if the coin isn't an issue. I guess we both have some more research and thinking to do, lol! When the dust settles in the end I personally still like the advantages of the 9" better.

[Zachalanche]

if you build an 8.8 right (including c clip eliminators), the only advantage that the 9 in has is the better supported pinion, and increased tooth contact area. which would be preferable for really hard launches, but unnecessary for most everything else. the advantage of the 8.8 with its slightly reduced tooth contact area is less parasitic loss. The 8.8s are also lighter (unless you compare to an aluminum 9 in 3rd member, then I don't know).

I run a 9 in because I have an old mustang that came with it. but had it been an 8in, I would have probably upgraded to the 8.8.

[1985olds]

I may be wrong about the 9" limitations, i read that awhile ago. I haven't found a solid number for the 8.8, but most will say a lot or more than most people will put through it. There are a lot of reports of people running 8's with them. I'm not looking for 8's or all of the horsepower, I know the 550-600 I'm looking to run will probably be the most I run. I drive The car everyday in The summer and am not willing to cross that full fledged racecar line. The problem I'm having is both rears will cost about the same at the end of the day and both have their merits.