How do you put a diff from an auto trans 79 into an 82? Is there a bracket or something to buy or build?

Thanks.

 

Oh I suppose anything could be done if you tried hard enough.. but it would be a major PITA. You'd have to change the rear cross-member in the car, weld in brackets on the frame to mount the cross-member and bunches of other stuff.. The 80-82 rear end use's the wing support from side to side to mount the rear end and the 79 has a cross-member.

Willcox

 

Welding stuff in is fine.

Are the parts available?

 

The '79 differential will bolt to the '82 batwing. The pinion bracket area might need massaging. I don't recall the longitudinal difference (referenced to the housing/cover plane) in "positioning" of the output yokes. The camber rods and bracket would need to be swapped, as they're slightly different shape between those years. I don't recall if the halfshafts are different length between those years.

Just some items to kick around to see what works best for you. I did a combination of iron differential/late batwing, and C4 suspension on my '69 a few years ago. Anything can be done if you think through it first.

Good luck!

 

Ok. So it'll take a bit of fabrication and some parts sourcing.

It's either get this to work or install a 4-link and a 9".

 

Out of curiosity, what are you looking to do?

 

Look here, the member is selling a differential cross member. Its a start.............

http://forums.corvetteforum.com/c3-p...-r-spring.html

8Valve

 

If the 79 diff is the same as the 71 iron diff it'll bolt to the batwing. I did it to my car and the only fabrication was cutting the end off the pinion bracket off. You also have to use the struts, strut mounts and half shafts from the earlier car...

 

Looking to build a reliable low 11 second street/strip car.

Cool thanks.

Thanks for the insight and suggestions.

 

Not so sure the aluminum wing will hold up to an 11 second car. I'm sure there are more of you out there that know more about this than I do.

I know on the c4 cars the weak point is the rear cover but only because the bolts will pull out of the Aluminum housing when spooled up. The MT c4 Dana 44 cars have pads that keep pressure on the caps in the rear end but even this isn't enough to keep them from blowing up on the strip.

 

Well, you could always just install a complete pre-'80 setup (x-member, HD cover and all), and perhaps step up to a 12-bolt IRS diff while you're at it. The frame mod might seem a step backwards, but it's not as drastic a step IMHO as ripping out the IRS altogether in favor of a live axle. And, tho not cheap, a proper 12-bolt IRS diff can handle more than 1000 HP, so the IRS strength issue is moot.

But, if you must, at least the Autofab 4-link / live axle conversion appears (AFAIK) to be reversable with a little effort, as long as you keep doing so in mind. In any event, I'd urge that you proceed carefully in the direction you're heading, as chopped up C3's w/ or w/o live axles don't tend to fetch very much on resale; exceptions being very highly developed and/or historic ones.

FWIW, I've recently acquired a C3 batwing myself specifically for studying what might possibly make it work for severe duty with 10 & 12-bolt IRS hogheads. Problem is, I don't know how long it will be before I can get my shark back together and running so I can test my theories.


TSW

 

The 80-82 Dana 44's have a bad rap for being weak. The weakest links are the smaller 1330 u-joints. Since all 82's switched to the bigger 1350 u-joints they are the same as the older cars. Probably the next weakest link is the Outer Axels and or the Yokes with no advantage to either the Dana 44 or the Iron Rear. Then probably the Dana 44 is prone to loseing its Posi Clutch pack wich dumps Metal in the Oil wich takes out the bearings. The C4 Dana 44 has stronger Bearings and bearing suports but is prone to Cracking the case due to the forward mount wich the C3 dosn't have. If you beef up the Axels use the best U-Joints and Yokes and have a look at the oil I think You might surprise your self on how long the dana 44 will hold up. With exception of the Yokes you will re use all these parts again if You switch to an Iron rear later.

 

all good comments, Thanks.

Currently, the car is a stock suspension 82, with stock gearing. The thought was to upgrade to an iron diff, since they came with 3.55:1 ratio.

So for parts, we've got the diff and the axles and flanges from a 79.

We'll need a cross member, struts and strut mounts.

I'll need to well in a bracket to mount some of this stuff. and maybe massage the iron diff to bolt to the batwing?

Or, just get the stock diff built with better parts, and a new gear ratio...??

 

Hard to make the call for you. If you've an auto w/o any trans-brake, you might possibly get away with beefing up the D44. That said, IMOE one doesn't have to be on slicks or dumping a clutch at insane revs to break even the 10-bolt diff. YMMV

Any stock C3 10-bolt hoghead should bolt right up to the C3 batwing, other than for the two lower-most side bolts. Flanged HD inner yokes will require some clearancing/notching on the 'wing, but that's no big deal. There are a few guys that are running C3 10-bolt/batwing combos here on the CF (hopefully they'll chime in), but not sure any of them are doing much in the way of drag racing. Some of the weaknesses discribed by Willcox are among reasons I'm looking into possible improvements myself.

Gearing wise, a 4.11 would really wake things up at the strip, but the 3.55 is hard to beat as an all-around ratio. Have a 12-bolt Eaton posi IRS w/ 3.55 myself, tho 1/4 mile ET's aren't exactly a priority for my shark. BTW, the word is to stay away from the carbon fiber plates!

Oh, and I've got a spare '68-79 diff x-member, if the need arises.

 

There have been several posts already explaining that you can use the IRS with an iron differential. That mod is about as bolt in as any you'll do on a C3. The only fabrication is to the pinion bracket. I can't see the older style crossmemeber and mounting of the differential being any stronger than the aluminium batwing crossmember with the pinion bracket.

 

Here is what I believe after reading the posts and your pictures;
The pinion bracket need some fab work to mount to the cross member. The bolt holes to mount the Aluminum Differential in the Bat Wing match the holes in the iron diff.

My only question, do the present bat wing mounts on the frame
allow the bat wing with iron diff to be in the right fore/aft location or do they need to me moved to properly locate the iron diff to the trailing arm yokes ?

Thanks
8Valve

 

Go to the parts section there is a guy selling a 370 rear gear diff from an 80 everything you need. Bolt right on and go. You might want better u joints. Or get ahold of Tracdog to rebuild a bulletproof aluminum D44 for you.

 

8vavle, yes, you have to cut the front tip off the pinion bracket to clear the frame crossmember. The batwing locates the diff right where it needs to be. You can even use your current driveshaft.

 

Some more great info here. And thanks for the pics.

 

I looked for the thread selling 370 diff and couldn't find it. You have a link by chance?