Upgrading Dana 36
Melting Slicks
Joined: Nov 2008
Posts: 2,765
Likes: 5
Change the fluid out to a modern 75-90W synthetic gear oil.
Royale Purple is what I use in my 87 vert rear diff.
And 1 bottle of GM limited slip gear oil additive from my local GM Chevrolet Dealership.
Save your $$ up for a dana 44 C4 rear.
Or install a modern Ford 9" inch rear, 12 bolt Chevy rear, or dana 60 rear for big Power over 1,000 HP.
I have a Dana 44 C4 rear diff I replacing in my 87 later this month.
Keeping my dana 36 for a spare just in case.
Brian
Melting Slicks
Joined: Nov 2008
Posts: 2,765
Likes: 5
Both keep taking a licking and somehow keep on ticking.
Change out the rear diff fluid to a modern synthetic gear oil Sammy & 1 bottle of GM Limited slip additive.
Put the drag radials on an go racing.
It will take more than 1 full power pass before it fails.
Unless you forget to put gear oil in 1st.
Brian
Melting Slicks
Joined: Oct 2000
Posts: 3,426
Likes: 4
From: Heidelberg PA
Cruise-In V Veteran
You might want to try redline heavy shock gear lube and no additive is required. I know I have a Dana 44, but I have been running 1.50 60foots for 3 plus years. I did upgrade my internals to a truetrac this year to open up the motor and see what she can do.
Le Mans Master
Joined: May 2007
Posts: 8,448
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From: Valparaiso
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Melting Slicks
Joined: Oct 2000
Posts: 3,426
Likes: 4
From: Heidelberg PA
Cruise-In V Veteran
If you are driving it on the street - no drag radials or slicks, then there is plenty of slip, you shouldn't worry about it.
If you hook hard - the differential, especially the spider gears can self destruct and take your case with them.
If you hook hard - the differential, especially the spider gears can self destruct and take your case with them.
Race Director
Joined: Apr 2003
Posts: 17,699
Likes: 1,667
From: moraga ca
Melting Slicks
Joined: Nov 2008
Posts: 2,765
Likes: 5
The C4 dana 44 has only a 7.875" or 7-7/8" diameter ring gear.
The C4 dana 44 rear has a 8.500" or 8-1/2" diameter ring gear.
The housings and bearings caps are Alcoa made aluminum castings.
Strong material but still a weak link when drag racing and feeding huge power over 600 HP and torque numbers to match.
If I break my c4 dana 44 rear I have a 1957 Pontiac rear with a 9.300" inch diameter ring gear and 35 spline Summer Brothers race axle shafts with a matching steel spool. 5.57:1 gears installed at the current time in that rear.
Have other gearsets in the 3.64, 3.90, & 4.10 brand new put away for it.
1957 Pontiac rear diffs have same track width as a 1970 Chevelle & GTO.
Hard to find rear these days.
BR
The C4 dana 44 rear has a 8.500" or 8-1/2" diameter ring gear.
The housings and bearings caps are Alcoa made aluminum castings.
Strong material but still a weak link when drag racing and feeding huge power over 600 HP and torque numbers to match.
If I break my c4 dana 44 rear I have a 1957 Pontiac rear with a 9.300" inch diameter ring gear and 35 spline Summer Brothers race axle shafts with a matching steel spool. 5.57:1 gears installed at the current time in that rear.
Have other gearsets in the 3.64, 3.90, & 4.10 brand new put away for it.
1957 Pontiac rear diffs have same track width as a 1970 Chevelle & GTO.
Hard to find rear these days.
BR
Last edited by 87 vette 81 big girl; Apr 17, 2011 at 12:17 PM.
