What rear to Use 10bolt 12bolt or 9"

[rohrt]

I would like to acomplish the goal of having a strong safe differental for a road race/1/4mile/street car (mini tubed)with 600ft/lbs or torq. I wanted to look for best and least expensive route for my application.

My first thought was a ford 9". I was looking at the 77-78 Lincoln versailles with the disc break setup. This is supposably a drop in for my 68 Firebird. This is 1 1/4 more narrow wich is good for me with the mini tube. Then I read this artical.

http://www.mustangmonthly.com/techarticles/26478/

I knew nothing of the 9" so I ejucated myself with these articals

http://www.kevinstang.com/Ninecase.htm

http://www.dfwmotorsport.com/Fairlane/9inchrearends.htm

I added up the cost of going this route and the fact that parts are getting hard to find with that disc break setup the axles would need to be 4 3/4 for the lugs then the disc rotors wouldn't fit, it uses 2-3% more power. The center section would need to be changed out and I think it uses the smaller bearings. Then I read this artical

http://www.chevyhiperformance.com/techarticles/0304_nine/

The 12 bolt sounded like a pretty route to go so I followed the link to them

http://www.moserengineering.com/moser_interior/products.asp?CatID=29

Looks like a great rear to go with but now I'm back to a 2000 dollar expense.

I would like a rear that is a little more narrow to get a deeper look on what ever rims I buy in the future but this is not critical to me. So now im wondering if I should just just stick with my stock 8.2 and get a new center section for it from Moser set up for 30 splin axels and get the axles from them as well. My Pontiac doesn't have C-clips but has bearing pressed on the axles. It sounds like their gears are stronger then OEM as well as their axles. My concern is road racing at 150mph(I might be dreaming) and break a axle hub off or have axle bearing fail. I don't know if this is a realistic concern or not or if the 9" or a custom fit 12bolt is over kill? Would like to hear everyones comments on this.

[dennis68]

A 12-bolt is pretty heavy and a 8.5 10 bolt- can easily built to be just as strong. Anything you can do shave weight off the axle will help on the road course. The 9-inch is the heaviest of the 3 but also the strongest and easiest to make changes to (specifically gears). A lot of road course guys run the 9-inch so they can put the Detroit and 4.11's in for the track and the limited slip 3.50 is on the street.

I guess it all boils down to how much do you want to spend.

[JLM]

There are some pretty decent open road courses here in Colorado, a couple with decently long back or front straights that cary some speed. You'd have to have a LOT of power and minimal weight to reach 150 I think. A Roval (oval with a road-course) like PPIR you may see speeds close to that. Honestly I would stick with the poncho differential and get a high quality center section with at least 30 spline axles. That should suite you just fine and it will be cheapest on the wallet.

[Derek69SS]

stock vs. stock, a 9" is NOT as strong as a 12-bolt.

12-bolt has 2 drawbacks, C-clips (on chevys, not on BOPs) and that it's difficult to swap gears.

8.5 10-bolt can be made just as strong as a stock 12-bolt. Do the same mods to the 12-bolt, and nothing compares (except maybe a Dana???)

8.2 10-bolt will hold up for a while, but not forever behind 600ft/lbs.

9" takes more power to turn, I know of one car chassis-dyno'd with a 12-bolt and then a 9". It had 12 more hp at the wheels with the 12-bolt. They have one benefit: Easy to swap gears.

[cw67]

I went through this same dillima about a year ago. I bought a lincoln versailles rear end and brought it to the guy that was going to set up the rear for me. He knew a guy that had a 12 bolt for sale and talked me into buying that one and just swapping out the gears. I'm pleased with the 12 bolt and it was a direct bolt in. I liked the idea of the 9" being narrower for deeper rims and a mini tub. I guess I let everyone talk me out of mini tub for now. I have the Versailles rear end for sale if you decide to go that route.

chris

[rohrt]

I plane on using a TKO 6 speed and I have all the gearing figured out. A 9" is great for the gear changing but I guess I don't see myself doing much if any gear changes.

What mods do you think would make a 8.5 as strong as a 12 bolt? Anyone no if they are making a True trac differentials for the 8.5 BOPs?

[wally8]

OK, I'm going to need more info. Just how is a 12 bolt stronger than a nine inch and under what sort of extreme circumstances? I know the power transmission efficiency thing. The 12HP number comes from Cup testing under Cup racing conditions. I'm not calling BS, I just want some real durability numbers.

Fact is I've seen and used 9 inchers under some pretty rough conditions and I'd be impressed if you broke one on a road course.

If your budget is in the $1500 range, you'd be hard pressed to beat a 9" floater for this app.

You can get one for $750-$800 and that includes rotors and 31 spline axles. Just add the pumpkin of your choice. You can even get one that uses 12 bolt gears if you want that 12 HP back. Then you can guarantee safe performance at 150MPH.

I'm not sure why everyone wants to put money into an 8.5 except that it must be a bolt in deal. But then so is a floater.


Wally

[dennis68]

I'll back Wally up on the durability issue. The 9" is by far the strongest axle going for this application. Some will say maybe a Dana 60...I work on those all day, as long as you don't mind replacing bearings and occasionally losing a pinion then maybe.

A floater 9" while possibly requiring a little fab work (welding on mounts for links or leafs) is the only way to go IMO.

[wally8]

I hate to keep referencing circle track in every post but one thing should be apparent now. If it can be done cheaply while still giving very good performance, the CT guys are doing it.

Fact is you can't build a better racing rearend (or high performance street) for less money than a 9" floater. If you think you can then you better let the CT guys know because they will literally buy thousands of them from you. If it was really cheaper and better, they'd already be using it.

I might concede the issue if we were talking drag racing since those are apples and oranges applications. Roadracing and oval track with stick axles are pretty much both apples (or oranges if you prefer).

SIDE NOTE: If you're looking to build a good handling F, A or G body you really need to look to circle track suppliers. This is where knowing some theory can really save you some major $$$$. Why pay for a WD chassis when you can build the same thing for under a grand (different components, same results). That is unless money is not a barrier (I'm a cheap *******, myself).


Wally

[yody]

nothing wrong with 8.5 ten bolts, people are running deep into the 10's and 9's with slicks. To upgrade a 8.5 10 bolt you need a very good 30 spline posi like eaton, 30 spline aftermarket axles, and a good set of gears like U.S gears are any other of the top guys. A rearend girdle is a good idea too. You can put one of these together for about $1500 total. Should be almost as good as a built 12 bolt

[wally8]

I think that's the mistake people are making here.

So what if it's tough enough to launch a car in a straight line. Big deal, who cares? That's not what this app is really about. What you want to avoid is killing yourself at 150MPH (or even 100) because you broke an axle and the wheel fell off as a result. Drag axles and road race axles are different. Different materials and treatments. You shouldn't be using drag axles for road course work.

I've seen some of the lower stock car classes try to use rearends other than floaters. Everything from stock to high dollar drag rearends that they got for cheap from someone at a swap meet. The axles break, simple as that.

People make the same mistake on motors. They think they can build a drag motor that makes X amount of HP and that it will be a great motor for a track with corners cause, hey it makes X HP. What they don't realize is that you have to really build a motor in a specific way to hold together lap after lap. Completely different applications.

Wally

[rohrt]

Wally8
What do you mean by floater? Do you have some links to what the circle track boys are running. I would like to see some of it for my self.

My first plan was to install a 80 TA disc 8.5 disc break set up in my car. I may go back to that plan. If I can accomplish what I want to do with what I got I will go that rought. The 80 TA does use c-clips. I see Moser sells c-clip elimenators and also axle ends. Not sure if either will work in my application or not. I also checked and found that Truetrac makes a 8.5 version. $400 for a True trac differential, 320 for moser axels ends $80 a pair, rign an pinion $175

I would love to through $2000 or more for a brand new 12 bolt setups but like I said if I can accomplish what I want to do with what I got then its more money to through at something else.

What are some of the rest of you running?

[wally8]

Here are two links:

This is the cheapest: http://www.randysracemart.com/9infoflas.html

This place would be easier to get a custom width and they also do a lot of custom housing apps: http://www.quickperformance.com/

You should consider the fact that you're getting rotors with the package and you can get any kind of caliper bracket that you want (from a cheap stock GM to 3.5" brackets for high end aftermarket calipers) cheap as well. Not to mention all of the various suspension brackets for locating links and PHB's that are available.

When you add it all up for real, I think you'll find that you're spending very little extra to get a much better rearend. Gears are less, axles are less, hubs are more but not much considering you don't have to buy new bearing ends and you have to pay for the housing. Top it off with the fact that you can swap gears easily. It may not be somehting you want to budget for now but a couple years after the car is done you have the option.


Wally

[wendell]

Wally,
great info. It wasn't too long ago that the CT stuff was a really well kept secret.

How fast and for how long untill you need to start looking at rear end coolers with the 9"? I know that you don't have to run a cooler with a QC. Can a QC be made to live under a heavy street car?

Jensen

[wally8]

If you run synthetic lube you'll likely never need a cooler unless you're going to run at top speed for say 500 miles or so.

A QC would be really cool since they're all magnesium and aluminum. I'm just not sure how they'd hold up on a heavy street car. Surprisingly they're not a huge amount more than a floater. Don't get me wrong, they're very tough rearends.

Wally

[rohrt]

I still don't know what a floater is. I usally flush them when I can. Does that just mean it has no mounts welded to it?

[dennis68]

The axles "float" in the housing, they are not retained by anything other than the fact that they can't move via a hub similiar to a front hub on the housing ends. Think tractor/trailer set-up only smaller scale.

[wally8]

Yes, they're actually 3/4 ton pickup hub snouts. The outer hub is retained similar to a front hub on your front spindle but it's splined in the middle to accept the axle for a drive.



Wally

[yody]

I would like to acomplish the goal of having a strong safe differental for a road race/1/4mile/street car (mini tubed)with 600ft/lbs or torq. I wanted to look for best and least expensive route for my application.

I think it is safe to say for what he is doing that a typical rearend setup with your common components will hold up for what he is doing. I don't think he needs a nascar rearend setup, as most pro-touring cars that have competed in events such as the RSE and others don't have floating 9" nascar rearends.

For my info can you please specify what makes road race components different from drag race compenets? Obviously there aren't going to be a lot of side loads in a drag app but what is the difference in the parts.

I could see if he was builidng a oval track car or a high horsepower basically track car but I don't think that is what he is doing. Also what about a drag race axle breaks in a car that goes aroudn corners? Also most pro-touring cars have rear wheel disc, won't that retain the axle if it breaks?(not that you would want that to happen or rely on the brakes to hold your axle in!)

[rohrt]

Those floater assemblies look like you get alot for you buck. Is the main advantage that if you break an axel the wheel stays put? What about disc breaks and getting 4 3/4 bolt spacing on the axles? Any concern I should have with emergency breaks? Looks like a neat set up.

[wendell]

rohrt,
I think Yody is right, a floater 9 is way over kill for the average PT car. I can think of 2 big advantages to a floater. One is strength, the axel is isolated from all forces except twist from the ring gear. Seond advantage is that you can set up a floater with camber meaning that the drive plates don't have to be perpendicular to the axels. Potentually very cool...

[yody]

definetly very cool, i have seen them on ebay for cheap too, however i somewhat recall that they are some of the heaviset rearends and they are not just a bolt in?

[DLinson]

Witht he hub protruding past the bolt flange, this may interfere with many wheel styles. Do they make a floater with only about a 1/2" hub like a standard axle? The circle track guys don't care about the wheel styles as much as most of us do.

DLinson

[dennis68]

Overkill...I don't think so. What is the difference in spending 1200 building a 12-bolt or spending 1200 having a floater put together? The floater will be cheaper to fix in the long run, last longer, be safer, and require less maintence.

They are not the heaviest...in fact with an alumnum center section (which is not an option for a GM axle) and lightened gear sets they weigh less than a 10-bolt. 9-inch axles ahve far more available as far as upgrades to increase strength, durability, and weight.

I don't see any reason why the hubs could not be machined down to fit most wheel centers

[wally8]

You could certainly say it's overkill but I guess my point is that for very little extra money (if any) you can have that overkill which isn't a bad thing. The weight penalty is very slight.

Someone asked about E brakes and that would be a problem. There's no provisions for that. I guess you could use a pinion brake like the street rod guys use or just carry some chocks in the trunk :-)

Yody,
As far as I know they use different material (drag axles are more brittle) and I believe a different treatment process (heat treating / hardening).

You can get the hubs in a 4 3/4 pattern and the hub snout would probably fit under a lot of wheels although I would cover it up. It looks really good with an anodized cover and some nice allen bolts.


Wally

[rohrt]

This has been a good discussion but I'm far from being convinced to go in any direction yet.

Beefing up my 8.2 or getting a 8.5 80s TA disc would be the simplest for me but dosn't save much more money compared to a floater.

The Floater seems very cool and very strong with much fabrication to install then I have the question of how to install it. 4 link or leafs. Seems to be the safest and strongest also

It dosn't sound like a 9" or 12bolt would have much advantage compared to these two choices.

[BRIAN]

Ok so what is the draw back to using this set up on the street? I agree if you look at the CT web sites the parts are dirt cheap and appear adaptable. Has anybody actually used this set up on the street? Anybody ever attempt to bolt a street style wheel up? No; "I think it will work", but actual; "Yeah I have it on my ride and it works", is what I am looking for. Thanks

[rohrt]

The other thing is I'm going to realy need a parking break if I have a manual tranny.

[79TransAm]

IMO id go with a 10bolt. What im doing is i bought a 80 TTA. It has the 8.5 10bolt with discs. Can be built to hold up like a 12 bolt, gears are EVERYWHERE!!! All i would reccomend which is what im doing is go with a set of mozer axles. I bought my TTA for $400, sold about $600 worth of stuff off of it, and now have a great rear for myself. If you can buy a trashed TTA salvage the rear and sell the rest like i did id say your ahead of the game.

[rohrt]

The big drawback that I don't like on the 8.5 it it has the c-clips and its wider not by much but its still wider. I wonder if I could put the axle tubes from my 8.2 (Press on axle beardings) on a 8.5 rear and get ride of the C-clips? I would have to do some comparing to see if the breaks would still work with the diffrent tubes.

It still comes down to there is no bullet proff cheap solution solution like I was hoping for. I could go with any option out there but to make it strong and reliable I'm going to have to spend money. I do like the 8.5 and if I can find a 80 T/A disc set up I'm going to snatch it up.

[dennis68]

Brakes from an 8.2 will work fine on an 8.5 tube....they are all the same.

[rohrt]

I was thinking more of using the rear disc set up from a 80 TA on a 8.2 tube. I would think there has to be some diffrences.

I found another good artical on beefing up a 8.5
http://chevyhiperformance.com/techarticles/48518/index.html


What are gun drilled axles?

[dennis68]

I was thinking more of using the rear disc set up from a 80 TA on a 8.2 tube. I would think there has to be some diffrences.


They will work just fine. That is the original PT brake conversion.

[yody]

i hate those stupid WS6 rear disc, i wouldn't do that you can do a 4th gen conversion easier. also if you have a first gen you don't want the second gen 8.5 you need a 73 and up nova 8.5 10 bolt which are actually pretty easy to find, they won't have posi but they will bolt right in

[rohrt]

I plan on mini tubbing anyway so the perches would need to be re-mounted and if plane on getting new axles anyway. That just leaves a center section and a housing. I want 30 spline so I would have to order a new center to accept 30 spline. I would like to have the housing shortened and replaced with the 8.2 or use a diffrent axle bearing all together. Crap!!! now its not simple and cheap anymore.

Yody do you have any info on that 4th gen rear break swap?

[dennis68]

Buy everything from the backing plates out for a 4th gen LS1 car and install it. Check out the brakes section and search LS1 rear discs.

[rohrt]

I looked at the LS1 setups. Very cool I knew about the fronts being adaptable but I didn't know the rears would work to.
http://www.camaros.net/techref/articles/brakes1.htm This site has it all put together rather nicely. Do you think it would be better to get the hybride system or just by off of ebay.http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=7977261141&category=33564&sspagename=WDVW

I did see someone was putting this system on their car and he had switched to ford bearings ends on their axle. I would like to know more about this. Are they superior to the gm ones or are they just like the press on 8.2s that I have now? Is the diameter larger? Is the flang the still a GM flang for bolting up the backing plate? I would assume you need a aftermarket axle to go with the ford bearing? Just wondering what the advantage is over a presson 8.2 bearing.

Oh and thank you for the heads up on the rear disc break setup.

[rohrt]

I called Moser and got my question answered. GMs press on bearing had a .1377 ID and a .2562OD that was close to the small bearing Ford of .2834. The larg bearing Ford used a .1531 ID and a .3150 OD. Moser sells Housing Ends that use the Larg Ford Bearings and a GM flange for around $80. They also sell the cone stly bearing that can take side loads better. True trac makes a 8.5 30spline setup for $455 and has a 8.2 in the works. I didn't realize that the 30 spline axle is actually a bigger diameter axle. Moser sells the axles for $315 and complete with studes bearings and retainter plate for 100bucks more.
I was considering narrowing a T/A 8.5 housing myself at home(not sure if thats wise) using the larg ford bearing housing end, True Track center section and 30 spline axle with US Gear gears. So lets add this up
30 spline axles/w bearings 415
30 spline TrueTrac diff 455
Ford Housing ends 80
gears 170
setup kit 100
Is $1220

That being said the idea of using a 9inch floater sounds better all the time.

[Tom Welch]

If you decide on a 9 inch, get one from a 64-65 Thunderbird. It is almost a bolt in for a first gen. I got one from a 65 and went through it. It's a tank. easy to set up, spring perches are within 1" of my 67 firebird spring pads. Too easy.

[David Pozzi]

I may narrow my 12 bolt myself. They sell kits with a large mandril bar that fits through the center bearing saddles and mandrils fit on the bar to keep the outer ends straight. You need a good cutoff saw to keep the housing ends square and of course good welding must be done.

Actually, you can get a housing shortened pretty darn cheap by someone who allready has all the special tooling.

I'm going to get the large ford outer bearings, good axles, stock 12 bolt splines. I have a 6 speed, so won't need to do gear changes.

I like the 12 bolt size, weight, better efficiency/lower fluid temps. Plus, I allready have one. My 69 Camaro has a 9" with floater axles. I haven't run it or really done anything with it since I bought the car. It has HUGE 5/8" studs and the prev owner drilled out his cast wheels to fit them on the studs. The center hole of these wheels is larger than it needs to be for some reason and there is hardly any metal left between the stud hole and the center hole. I'm worried about the wheels breaking. They also tried to put inserts in the stud holes with tapered seats to run NASCAR type lug nuts. The seats come loose when they put the wheels on because the holes are too small over the studs. The floater requires a larger pilot hole in the wheel, you can get 4 3/4" bolt circle hubs from AFCO. I'm going to redrill mine so I have interchangeability between my cars.
I'd use 1/2" studs or the current 13mm metric studs, they are almost 1/2". When I did my wife's 73 10 bolt, I installed the metric studs to match the front Baer Track kit studs, so there would not be a possibility of accidentally getting them mixed up.

I'm not knocking the 9", I think it's pretty good but I hate to add more weight. If I didn't have the 12 bolt allready I'd look at the aluminum ctr section 9". It would be nice not to have to shim the carrier bearings when setting up gears for once.

[bnickel]

the versailles rear is nearly bulletproof as is, it's a heavy pig to be sure, though. it does have some advantages though since it is a 9", like has already been said gear changes are a snap, aluminum carriers are available and they actually use the big bearings not the small ones.

another cool thing about the versailles is the way the caliper mounts are made, they are a 2 piece design, a caliper mount and an axle mount, i've been in some discussions about and you can actually change the rotor size from the stock 11" to whatever size you want by simply making a spacer and using longer bolts, very cool, you can also make new caliper mounts and change the style of the caliper as well.

the versailles gets a lot of bad press, most people are under the impression that it uses a fixed caliper which is totally incorrect, it has a sliding caliper, also parts really aren't that hard to come by or that expensive either, i bought caliper kits for mine for about 12 bucks each and i found a pair of brand new bendix rotors on ebay for 50 bucks for the pair plus like $18 shipping. moser or strange can build 31-35 spline axles for it and also if you don't like the stock brake setup you can easily change it over to an explorer disc setup with the drum style parking brake.

check out this guys page he has some great info on the versailles rear and especially the explorer brake swap. www.ultrastang.com

[rohrt]

What to do what to do.....

Bnickle good info and good link. I didn't know that it had the larg bearings. So there must be two diffrent version of the larg bearings? One for the 28 spline and one for the 31 spline axles???

Yo! Pozzie "My 69 Camaro has a 9" with floater axles" I want more education on the floater 9" It seem like a awsome way to go. There was the post that had the link to a $800 floater kit. As cool as it was it seem like the rear break set up was a little weak. Like it was made for a very light dirt car and It was already mentioned I would have no parking break and I don't like thoes pinion breaks. I like the idea that they can take extream side loads.

I'm really leaning tword the Idea of building a bullet proff 8.5. I went junk yard hopping today and came accross a killer deal on a 73 omega. I can get the front sub frame and rear(8.5 right????) for 125. The front sub has disc breaks to. As much as I like the 9" and what it can do. I just see running into expensive problems with break setup and such. The LS1 rear break setup sounds great to me. There dosn't seem to be any clear direction to go with this so it just seems best to stick with GM over Ford. I don't know unless I came accross a killer deal on a versaille rear. Since I plan on getting new axles no mater what, I can do what ever I want and it all cost about the same.

[t72ss402]

I am running a direct bolt in 9" in my 72 chevelle, 4.10 gears, rebuilt traclock, 31 spline axles, and rear disc brakes. All i have invested is around $1200.

[nestockcar]

We used a full floater 9" on our CT 76 Street Stock Camaro a few years back. For about $1200 it was by far the best rear I've used. To mount it all you need is the Clamp-On leaf spring pad. This allows you to mount and adjust the rear, and even drive it (very slowly and carefully), prior to welding it. Ours came with the brake bracket welded on, then we just installed some Wilwood calipers and away we went.
We switched tracks and had to go back to our 10 bolt. The rear was sold and is being used successfully on a street driven camaro.
When I'm ready for it a full floater 9" is what I'm using.
I purchased the rear at www.cmwraceparts.com (http://www.cmwraceparts.com/).

[inSANe DIEGO]

Hey guys,
Will the 9" floater accept an Lt1 or Ls1 rear brake setup? If it is possible, will it take more fab work other than a flat bracket shape like when doing disc conversion on the front of a 1st gen Camaro? I liked the ability of the brakes' direct bolt up on the 10 and 12 bolts, but I'd rather go with the floater if reasonably possible.

[rohrt]

From what I have seen, No! There is no flang to mount to. It uses a hub setup. Thats why I was questioning the break setup on these. It looks a little small for a street car.