Numerically higher R&P for my 81?
12-25-2011, 11:25 AM
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Numerically higher R&P for my 81?
I have an 81 with a 4speed. I have read that the rear of these cars are kind of a DANA 44 type set up for vettes. Will a DANA 44 R&P work in this rear or do I need something corvette specific? Where would be the best place for this purchase? Suggestions on which R&P I should go with are also welcomed. I want something streetable that won't be too spooled up at interstate speeds. Thanks in advance and Merry Christmas.
12-25-2011, 12:01 PM
#2
12-25-2011, 12:44 PM
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go to www.jegs.com, the best all around choice would be around a 3:55.
12-25-2011, 01:46 PM
#4
Team Owner
Been a while, and I have the flu, so I forget the handles exactly...you want to go with the recommends of either one of two guys who are long time forum members and VERY knowledgeable on these diffy's
one is Gary...GTR1999 or 99 do a search.....another is Mike, and I forget his handle but a kid doing extensive work on his car with Mike's supervision is STINGER so look him up, and he can hook you up with Mike in a nanosecond....Stinger's project is of long standing many aspects, it's the diffy guy, MIKE that you need talk to....
if you have troubles, email me, and I can maybe find them when I feel better....flue on Christmas SUX....
one is Gary...GTR1999 or 99 do a search.....another is Mike, and I forget his handle but a kid doing extensive work on his car with Mike's supervision is STINGER so look him up, and he can hook you up with Mike in a nanosecond....Stinger's project is of long standing many aspects, it's the diffy guy, MIKE that you need talk to....
if you have troubles, email me, and I can maybe find them when I feel better....flue on Christmas SUX....
12-25-2011, 03:38 PM
#5
Drifting
ZZ,
The gears and everything else inside is corvette specific. These diffs were only used for 3 years. The best place to buy Dana gears is thru Toms. What are your future plans for the car? If you stay with the 4 speed and the 383, 3.31 gears may be a better option due to the low to mid range torque of the engine. If in the future you decide to go 5 speed then 3.55 or 3.73 will work better for you.
These diffs have a weak spot, the left side bearing cap. Regardless of which combo you choose, you are still doubling the load these diffs were designed to handle. Do a search on Dana 44 and you will see how I cure this problem.
Mike
The gears and everything else inside is corvette specific. These diffs were only used for 3 years. The best place to buy Dana gears is thru Toms. What are your future plans for the car? If you stay with the 4 speed and the 383, 3.31 gears may be a better option due to the low to mid range torque of the engine. If in the future you decide to go 5 speed then 3.55 or 3.73 will work better for you.
These diffs have a weak spot, the left side bearing cap. Regardless of which combo you choose, you are still doubling the load these diffs were designed to handle. Do a search on Dana 44 and you will see how I cure this problem.
Mike
12-26-2011, 12:08 AM
#6
Melting Slicks
The first thing I would do is put in a 5 or 6 speed Trans. The TKO 600 is probably the most common swap and with its 2.97 first gear it will really wake things up. Randys Ring and Pinion is a supplier for Ring Gears as well as Toms Diffs. Keep in mind as stated above that the 80-82 uses a Gear of its own somethimes people thinks its the same as the C4 Dana 44 and its not. Randys Web Site has an excelent Speed x RPM x Ratio Calculator that You can try any combination of Tire, Trans and Gears out with. On the Used Market 80-82's don't sell for much the 1980 Dana 44 uses 3.08 Gears your 81 probably has 2.87's. Because Your car was a 4 speed it has the good 1350 U Joints You will have to swap the Yokes into a Rear out of an Auto 1980 if You go that route.
12-26-2011, 04:24 AM
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Thanks for the responses. The T-10 4 speed is going to have to stay for the time being. I've got over 7 grand in the ZZ with accessories at this point. The rear gear is currently 2.72 to 1. I had found Randy's since this post but thanks for the input on Tom's. Still looking for your fix Mike. I expect the rear end will grenade if I get traction.
12-26-2011, 10:09 AM
#9
Melting Slicks
Thanks for the responses. The T-10 4 speed is going to have to stay for the time being. I've got over 7 grand in the ZZ with accessories at this point. The rear gear is currently 2.72 to 1. I had found Randy's since this post but thanks for the input on Tom's. Still looking for your fix Mike. I expect the rear end will grenade if I get traction.
12-26-2011, 12:52 PM
#10
Drifting
Actually the only thing the 80-82 diff shares with the Viper is the fact that both cases are made out of aluminum. That's it. Not even the configuration inside is the same. If you look thru previous threads you will see where I explained why some are harder to break than others. In '84 they were completely re-designed. The only thing that stayed the same was the size of the cross shaft bore. The Viper and the C4 D44 diffs mimic the design of the C2-C3 iron diffs. Except the caps have a full one inch of material above the bearings and they added a bump stop into the batwing to prevent cap stretch. And yet the caps still crack.
On the 80-82 Dana you have a slotted aluminum cap with .400 of material above the bearing. Because the cap is slotted the mounting bolts have a large mounting face to act as a washer. The cap now has a large notch cut in it to clear the bolt face. The cap is bolted onto a non-machined surface and then is align bored. The distance from the notch to the bearing race bore varies as much as .200 depending on where it was placed before boring.
In the earlier iron diffs and the later D44's the case itself was used to support the lateral loading of the carrier. The 80-82 uses a step in the cap to support the load. When you hit the gas the load is being held by the cap, not the case. This was changed in 84 back to the iron diff design. The weak point is the edge of the notch and this is where they crack.
Look at the pics in this tread:
http://forums.corvetteforum.com/c3-t...tial-help.html
You can see the notches in the stock cap. If you look close you will see the mounting pad is machined true and the cap is supported by the case. I hope this explains why most most of this diffs fail and some don't
Mike
On the 80-82 Dana you have a slotted aluminum cap with .400 of material above the bearing. Because the cap is slotted the mounting bolts have a large mounting face to act as a washer. The cap now has a large notch cut in it to clear the bolt face. The cap is bolted onto a non-machined surface and then is align bored. The distance from the notch to the bearing race bore varies as much as .200 depending on where it was placed before boring.
In the earlier iron diffs and the later D44's the case itself was used to support the lateral loading of the carrier. The 80-82 uses a step in the cap to support the load. When you hit the gas the load is being held by the cap, not the case. This was changed in 84 back to the iron diff design. The weak point is the edge of the notch and this is where they crack.
Look at the pics in this tread:
http://forums.corvetteforum.com/c3-t...tial-help.html
You can see the notches in the stock cap. If you look close you will see the mounting pad is machined true and the cap is supported by the case. I hope this explains why most most of this diffs fail and some don't
Mike
12-27-2011, 12:40 AM
#11
Melting Slicks
OK so I was a bit genaric when I compared our 1st gen Dana 44 to the Super Dana 44 in the Viper. And I also realise once I start Useing my Car with its Longer Stroke Motor and my 315 Tires I might just push it over the limit. I'm aware of the Diffrences in the Dana's. I still havn't decided what path I will go when nessisary, however I have been collecting my options on the local Craigs list. I have a late Iron Pumpkin, a couple 4 speed Dana 44's, A C4 44 and Yes a second gen Viper 44. If only they had made the Bolt Patten for the Boomerang the same on all the 44's. ( the C4 and Viper are the same) it would of made it an easyier swap only leaving the Nose to Frame mount to deal with.
12-27-2011, 01:53 PM
#13
Drifting
Actually the only thing the 80-82 diff shares with the Viper is the fact that both cases are made out of aluminum. That's it. Not even the configuration inside is the same. If you look thru previous threads you will see where I explained why some are harder to break than others. In '84 they were completely re-designed. The only thing that stayed the same was the size of the cross shaft bore. The Viper and the C4 D44 diffs mimic the design of the C2-C3 iron diffs. Except the caps have a full one inch of material above the bearings and they added a bump stop into the batwing to prevent cap stretch. And yet the caps still crack.
On the 80-82 Dana you have a slotted aluminum cap with .400 of material above the bearing. Because the cap is slotted the mounting bolts have a large mounting face to act as a washer. The cap now has a large notch cut in it to clear the bolt face. The cap is bolted onto a non-machined surface and then is align bored. The distance from the notch to the bearing race bore varies as much as .200 depending on where it was placed before boring.
In the earlier iron diffs and the later D44's the case itself was used to support the lateral loading of the carrier. The 80-82 uses a step in the cap to support the load. When you hit the gas the load is being held by the cap, not the case. This was changed in 84 back to the iron diff design. The weak point is the edge of the notch and this is where they crack.
Look at the pics in this tread:
http://forums.corvetteforum.com/c3-t...tial-help.html
You can see the notches in the stock cap. If you look close you will see the mounting pad is machined true and the cap is supported by the case. I hope this explains why most most of this diffs fail and some don't
Mike
On the 80-82 Dana you have a slotted aluminum cap with .400 of material above the bearing. Because the cap is slotted the mounting bolts have a large mounting face to act as a washer. The cap now has a large notch cut in it to clear the bolt face. The cap is bolted onto a non-machined surface and then is align bored. The distance from the notch to the bearing race bore varies as much as .200 depending on where it was placed before boring.
In the earlier iron diffs and the later D44's the case itself was used to support the lateral loading of the carrier. The 80-82 uses a step in the cap to support the load. When you hit the gas the load is being held by the cap, not the case. This was changed in 84 back to the iron diff design. The weak point is the edge of the notch and this is where they crack.
Look at the pics in this tread:
http://forums.corvetteforum.com/c3-t...tial-help.html
You can see the notches in the stock cap. If you look close you will see the mounting pad is machined true and the cap is supported by the case. I hope this explains why most most of this diffs fail and some don't
Mike
12-28-2011, 02:23 AM
#14
Melting Slicks
When the C4 came out they called it the Super Dana 44. (1985, the 84 has a Dana 36) The Super uses a Dana 60 style input shaft and the side Bearings are Larger. Also the Main Bearing Caps are suported by the Batwing. All three of these make it stronger. The C4 has a bad rep of breaking the case where it Bolts to the Ladder wich conects to the trans. ZFdoc.com sells a retro bolt kit wich helps this issue as long as you install it before you have the issue. The Viper uses diffrent Mounting ( Coil Spring Suspension) but is probably about the same as the C4 on the inside.
12-28-2011, 11:09 AM
#15
Drifting
By far the 84 up Dana is a better design. You just can't use it without major mods. The 80-82 is not a bad unit. It just needs the steel cap. I can also modify the C4 carrier to fit in them. The 80-82 carrier has a design flaw on the right side clutch pack. They have been known to break the retainers holding the clutches. The C4 carrier is redesigned to eliminate this problem.
In my opinion a custom built D44 is stronger than a stock iron diff. I have three of them running in drag vettes with no failures. Many more in street cars. My Super 10 iron diff is by far much stronger than the custom D44 but price is considerably higher.
Gale: The Super 44 also uses the Dana 60 rear pinion bearing and the case has reinforcing ribs. Not all C4's have the Super 44. I wish they didn't go to the torque arm front mount. They fixed one weak point and created another. The batwing doesn't support the caps. There is a .020-.030 gap between the cap and the support block. It's just there for cap stretch. It would have been better if it did make contact and was made adjustable.
Hugie82: It depends on your cam. You don't want to run an engine at 1800 rpm if the cam's minimum cruise rpm is 2600.
Mike
In my opinion a custom built D44 is stronger than a stock iron diff. I have three of them running in drag vettes with no failures. Many more in street cars. My Super 10 iron diff is by far much stronger than the custom D44 but price is considerably higher.
Gale: The Super 44 also uses the Dana 60 rear pinion bearing and the case has reinforcing ribs. Not all C4's have the Super 44. I wish they didn't go to the torque arm front mount. They fixed one weak point and created another. The batwing doesn't support the caps. There is a .020-.030 gap between the cap and the support block. It's just there for cap stretch. It would have been better if it did make contact and was made adjustable.
Hugie82: It depends on your cam. You don't want to run an engine at 1800 rpm if the cam's minimum cruise rpm is 2600.
Mike
12-28-2011, 04:47 PM
#17
Drifting
12-29-2011, 12:28 AM
#18
Melting Slicks
By far the 84 up Dana is a better design. You just can't use it without major mods. The 80-82 is not a bad unit. It just needs the steel cap. I can also modify the C4 carrier to fit in them. The 80-82 carrier has a design flaw on the right side clutch pack. They have been known to break the retainers holding the clutches. The C4 carrier is redesigned to eliminate this problem.
In my opinion a custom built D44 is stronger than a stock iron diff. I have three of them running in drag vettes with no failures. Many more in street cars. My Super 10 iron diff is by far much stronger than the custom D44 but price is considerably higher.
Gale: The Super 44 also uses the Dana 60 rear pinion bearing and the case has reinforcing ribs. Not all C4's have the Super 44. I wish they didn't go to the torque arm front mount. They fixed one weak point and created another. The batwing doesn't support the caps. There is a .020-.030 gap between the cap and the support block. It's just there for cap stretch. It would have been better if it did make contact and was made adjustable.
Hugie82: It depends on your cam. You don't want to run an engine at 1800 rpm if the cam's minimum cruise rpm is 2600.
Mike
In my opinion a custom built D44 is stronger than a stock iron diff. I have three of them running in drag vettes with no failures. Many more in street cars. My Super 10 iron diff is by far much stronger than the custom D44 but price is considerably higher.
Gale: The Super 44 also uses the Dana 60 rear pinion bearing and the case has reinforcing ribs. Not all C4's have the Super 44. I wish they didn't go to the torque arm front mount. They fixed one weak point and created another. The batwing doesn't support the caps. There is a .020-.030 gap between the cap and the support block. It's just there for cap stretch. It would have been better if it did make contact and was made adjustable.
Hugie82: It depends on your cam. You don't want to run an engine at 1800 rpm if the cam's minimum cruise rpm is 2600.
Mike
12-29-2011, 01:34 AM
#19
Drifting
Actually it's a miss use of names. The C4 Dana is correctly named the C4 D44HD. I was using the wrong term. Internally they use the same parts. The only difference was the webbing in the housing on the later units. That's what I was refering to when I called it a Super 44, which is incorrect. I'll be building up one of these in a month or so with steel caps.
Mike
Mike
