87 vette 81 big girl

What is the maximum Horsepower and torque limits measured at the engines flywheel that a C4 Dana 36 and C4 Dana 44 factory differentials can handle before failing or catostrophic failure ? Both having the same final drive/gear ratio.

What fails 1st in each type of Covette differential 1st ? Is it the Carrier bearing caps ? Or is it side gears/ pinion gears within the differential assembly ?

I know sticky tires and 5,000 RPM launches are an easy death for most factory differentials out there allready.

What is a Super Dana 44 differential ? Is that the unit used only in the ZR1 Corvettes ? What makes a Super 44 unique ?

Thanks and this is a great forum for any Corvette owner.

Vette Threat

A local here has been going 8s in his Dana 44 for almost the last 10 years but I don't know how many times he has had to rebuild it. From what I have seen, they can handle what 95% of the people are making on the street but it's those hard launches on sticky tires at the track that blows them up.

Low 60 foot times with the Dana is a challenge, especially on a 6 speed.

1989TransAm

I would think it would be how the horsepower is applied. The shock from dumping a clutch or the smoother application of the power from a automatic transmission.

87 vette 81 big girl

Thanks for the input. Interested in how far I can push the horsepower envelope with my Dana 36. Dana 44's cost as we all know allready to purchase.
Just when can I expect a stock Dana 36 to fail ? Around 450 horsepower and a few good launches hooking up quick ? I have built 10 bolt and 12 bolt Chevrolet type "C" axles for drag racing running in the 9's and 10's without much issue. Even a few without c-clip eliminators, much to my dismay-against my advice. And many rear ends in the Fox bodied Mustangs for the "Renegade " series Mustangs running the 9's and mid 8's. Around the Joliet, IL area. c4 Diff's like in my 1987 vette are a new running-duribilty experience to myself.

REDC4CORVETTE

I have pumped 700 hp 654 tq through my 44 for 2 years and only broke the half shafts.Then I went to 950 hp 836 tq at the motor and ate the u-joints 3 times in 6 runs.I make sure I tork everything to factory spects.
I also have found if you stage just a little off center ,Bang the half shafts u-joints and outer spindle axles will blow.1.49 60' More than a few times will kill it real quick.
I have put 450 hp 382 tq at the motor on my D-36 3.07 1.68 60' and haven't lost it yet ,go figure.I have also noticed if the body when launching pushes down past the center point of the half shafts the rear will break u-joints and spindles.I run a spool in my D-44 and 3.92 gears.28/11.5 MT drag slicks 7 1/2 back spacing 10 in wheel.
You never know what these rear ends will do ,I run 9.37 with the D-44 but I don't trust it .

rodj

When they want to
Some have hammered on theirs for years with no probs and some done very little to break them.

The Vette D44 is called a Dana 44HD;
Dana 44 pinion with Dana 60 splines/yoke.
Only one type , ZR1 used same.

Also keep in mind there is no difference in the uni's / halfshafts /spindles; D36 v D44

Typical spindle problems with good clutches.


http://forums.corvetteforum.com/c4-t...-the-year.html

rklessdriver

The Super 44 (AKA D44HD) is standard equipment on all manual transmission Corvettes built from 1985 on. Nothing special about the ZR1, its the same as the rest of the 6spds.

As far as what fails.

D36's - break teeth of the ring/pinion gear. They are just weak diffs and when they go -they usually grenade.

D44's - break outer stub axles first. Once you upgrade them to something better, you can usually split the posi traction carrier in 1/2. After that you usually blow the caps off them. This is provided the bat wing bushings are solid and your C-Beam is tight because if the pinion of the housing rotates upwards, after a while your going to break the nose off housing.

There are no hard and fast HP levels for them. It all depends on how well the car is hooked up and how hard you shock the driveline. I broke stock outer stub axels all the time with a dead stock 6spd LT1 on a 150 kit with 26X11.5 M/T ET Streets.
Will

cwyates4

My dana 36 held ~420 rwhp for a year and a half...then I put on the et streets and lost it in two weeks. It went with a big bang, a big big bang. I have a dana 44 now. no problems yet.

AKS Racing

Very similar experience. Running low 9s, I am on borrowed time, but the sloppy 60' (1.7s) is what is saving me.
Aaron

87 vette 81 big girl

Thank You for Your Input and experiences to everyone out there that replied to this thread. Nothing matches Personal experiences or accounts while racing.

Has anyone out there tried to Cyrogenticaly treating a C4 Vette Driveline Parts for added duribility? Stock and aftermarket Componets.

How do C4 Vettes respond to a Live Axle swap such as Ford 9 " ?
Is it worth the hassle ?

Do C4 Corvettes experience severe rearend-downward squat while accelerating from a launch in stock form ? My personal lessons from drag racing GM F- bodies out of the 1970's, at all costs this is to be avoided.

When a live - solid axle car experiences severve downward sqat at the rear wheels, the rear tires are losing tremendous traction to the ground. It is actually desireable to have the rear/ tail end of the car rise up to a certain degree. This is called by chassis engineers the term "ANTI SQAT".

When the rear of a rearwheel drive car rises instead of lowering, You are achieving at least 100% traction capability to ground with the rear tires hooking. Drag race oriented 4 links have the capability to achieve over or around 130 percent theoretical Anti Sqaut.

My 1987 Vette is a Covertible/Auto car. In mostly stock form besides the ignition and exaughst mods.

Have suprised a few Subaru WRX Turbo Car owners out there more than once with my car. Those cars run out of steam after 85 MPH. While my Vette keeps pulling strong past 130 +. LOL.

Have a built 410 smallblock built for this car with pump gas friendly compression ratio. A ground pounder/torque monster.
Yet to be installed. Was wanting know the duribility of the Dana 36 and Dana 44 diffs in these cars. Have a much better insight what they can take before iniment failure now.

rodj

Been done ,most report added durability

http://forums.corvetteforum.com/c4-t...sion-kits.html

Biggest problem with stock IRS is when the **** drops it lifts the outside of the tyre off reducing the contact patch.My rears consistantly show wear on the inner half only.
Camber can be changed to compensate but not a good setting for DD

neat

There is no definitive answer. I've probably broken more rear end parts than anyone on this board (the picture that rodj posted is of my parts) and I was only making about 275 RWHP/370 RWTQ on motor, 400/550 on the bottle.

Through all my trials and tribulations, I was pretty much forced to become knowledgeable about the D44 and independent rear in my car. This is the scoop, as I know it:

The most common initial failure is the outer stub axles, or as they are often referred to, the spindles. Inside the differential case, the most common failure is the spider gears. Usually, when a spider gear lets go gravity will pull the pieces to the bottom of the differential case. There is very little room between the ring gear and the bottom of the case, less than .07 of an inch; consequently the pieces of spider gear get shoved into (and sometimes completely through) the bottom of the case. Normally, this ruins the case. However, the spider gear failure really isn't that common. The outer stub axles are a MUCH more common first failure, in the neighborhood of 100:1, maybe more.

Cryo-treating hasn't helped me at all. I broke half a dozen cryo treated outer stub axles, a cryo treated half shaft, and a cryo treated ring and pinion.

The best solution is to get some larger spline outer stub axles from Summers Brothers Racing. They can also supply a rear hub bearing that has been broached to accept the larger spline count/OD stub axles.

Next, either chromoly or carbon fiber half shafts. Most people can find a local source for these things. For example, here in NC, there is a company that builds air plane propeller props out of chromoly. For $400-$500, they will build a set of C4 half shafts.

Build some snubber extenders for the rear snubbers. On my car, dropping the rear snubbers exactly 1 inch resulted in the half shafts being perfectly parallel to the ground at maximum squat. When I launch the car (and nothing breaks and everything works right) I'll ride the snubbers for the first few feet of the track because the car is squatting fairly hard. Without the snubber extenders the differential can go past parallel under extremely hard squat conditions.

If you just drag race the car, a spool is a great way to make the indy much stronger. I used one for awhile and liked it. I eventually took it out of the car, but it wouldn't kill me to put another one in. You'll lose some turning radius, but knowing that there are no spider gears in the case is a comforting feeling.

There's a ton more, but I've got to run. I'll come back in a day or two and write some more.

Good luck with your car.

87 vette 81 big girl

The response from everyone here is great. Appreciate everyones input about the C4's rear independent suspension and Dana 36 or Super HD Dana 44 Differential.

It appears one of the Corvettes greatest handling and ride attributes is also the acheilles heel when subjected to a good old hotrod thrashing/ pounding fun.

I drive my car daily in fair weather. Been reluctent to install this 410 smallblock because I was leary of the torque and horsepower capabilities of the factory independent rear setup.

I do love to stand on the gas hard at least once daily. Plenty of rural roads in my area to play outside of city limits. And have a few private 1/4 mile runs.

I can see it now, 410 smallblock installed, get the tires hot and sticky. Stop the car. Launch the car and let it hook up. And BANG. LOL. Broken Diff Assembly, U joints, Or a Outer stub shaft.

A late friend of mine that sold me this 410 engine, he built some years prior. Told me that this engine would surpass my wildest dreams and definatley perform. And if I took a brave soul with me riding shotgun, he would suddenly become a believer too, or start praying. LOL.

My 410 was destined for my friends '85 Vette. He didnt live long enough to install it. It became mine before he passed on.

His only wish was that I put it to use in my 87.

Also told me not let those rear tires hookup too hard or else.

Looks like it will take inovation, good old hotrod ingenuity, and some luck to make any Dana Independent Rear live for some time with this engine swap. Others have tried before me here on this forum.

Thanks again to everyone out there who wrote back here.

BR

neat

With the automatic, and a D44 upgrade, you'll probably be fine. It's not the power that breaks the parts, it's the sudden hit of a clutch drop.

With the automatic, I would think the D44 and other rear end parts would survive mid 1.5 sixty foot times pretty much indefinitely. You'll never come close to that on a public road, so I wouldn't worry about it too much unless you put a tire under it and hit a prepped track somewhere.

AKS Racing

I would bet that you waste the auto before you grenade the 2.73D36 (unless you have the perf gear 3.07D36), if the auto isn't fully built.

I have the same in the form of an '87 auto, vert, and wated the trans far more times than I care to remember back in the early 90s. Swapped to a black tag ZF in '96 and have had only one issue (when the clutch exploded).

Worry about the auto first behind the 410. These HP levels have been done many times around here with the D44.
Aaron

bobmic93

My 36 has held up a few yrs and at least 20 pass down the track. Im seeing 365rwhp and 350rwtq, low 1.8s avg and a few times dipped into the 1.76 range. A4 2400 stall 3.73 gears on Nitto drag radials 315s. I think if I bumped the stall up to 3200 it would blow it.

87 vette 81 big girl

Hi, I allready wasted the original 700R4 tranny in my Corvette a few months back. Exploded a plantery gearset. It is rebuildable. The case wasnt damaged.

Installed a 1988 Vintage C4 tranny that was a GM SRTA remanufactured unit I found cheap and recently removed for a LS1 6-speed swap.

Too many in town heavy throttle action for 2 + years and more than I care to say 150+ MPH jaunts. LOL

I plan on doing a full high performance rebuild on my 1987 Vintage tranny for this 410 Motor swap. No other way it can survive behind it I allready know.

BR

larry00

Defanetly build the strongest you can to reduce the chance of Murphy's law ruining your day at the track.
I had 550 hp w/the procharger and this drive train which handled it just fine.
No slicks though as car is driven on the street and even the Road track. It is a vette after all !
3200 stall , TCI built 4L60E Tranny and a Dana 44 with factory installed 373 gears and Spicer Off Road U Joints .
I only have 315 x 40 x 17 BFG TA Drag Radials cause I don't want them hanging out the fenders as I take the car to some local car shows too.
It will boil the hides at 60 mph on the freeway.
I see pic's of cars running 385's w/o Modifications to the fenders or sticking out .
It's in the backspacing but radically changing the geomentry of the car affects everything so I'm reluctant to go there.

I'm getting a couple more American Torque thrusts and a Pair of W rated BFG's for the Road Race Track work.
At 130 mph the thing is really screaming and 150 is really out there for any legnth of time.
It has the Z07 handing package and C 5 brake upgrade.
My recommendation is to !
Build it tough so you can forget it.

AKS Racing

Hmmmm.... I didn't know the factory installed 3.73s in the D44. If I recall, 3.54 was the largest gearset available. 385 tires????

AKS Racing

You may wish to check on whether your '87 is an early '87 or the later year '87, as the tranny was upgraded for the '87 model year (a whole host of upgrades, pump, sprags, sungear, etc), yet many of the early '87s got the previous generation of the 700R4.

That '88 tranny may still be the better bet with the 410 engine. Rebuild the '87 and keep it with the '87 OEM engine.
Aaron