Challenger RTA
Well-Known Member
After changing transmissions, rears gears. When I get gear lube on the cloths. I end up burning the shirt and sometimes the pants.
Stock 340 - Swap 3.23 for 3.91 gears - is Suregrip overkill?
- Thread starter Titan1969
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I did the same thing in my Barracuda. I went from 3.23 to 3.91. I bought a Eaton Tru Trac from Dr. Diff. This was about 9 years ago. The Eaton unit and the rebuild kit cost me about $650 and then another $400 for labor to have a pro to install the gears. Good thing I had a spare 489 case that had bad bearings in it to use. The advantage of a Tru Trac is it doesn't need the additive for the clutches and it (supposedly) never wears out. back then it was about $100 more than the Sure Grip with the clutches.
I got one of the early Tru Tracs and it did make a little noise. I ran into a guy at Carlisle who builds rear axles and he told me the early ones were known to be noisy. The Eaton Tru Tracs you get today are quieter. He told me to run a thicker oil in my rear and it should quiet it down. I just got done with taking out the pumpkin and cleaning out all the old oil. At my age of 59 this is not getting an easier (I don't have a lift). With the help of friend we also replaced the axle bearings. I am not sure if it was the new bearings or the thicker oil but my rear doesn't make any more noise. The guy at Carlisle (I forget his name) had a brand new pumpkin with 3.73 gears and a SG for $1500. Maybe the case wasn't brand new but it looked new. My firend bought that for his Dart. The guy said he could have sold a dozen of them. the one disadvantage of the Tru Trac is (if you are running the factory tapered bearings) you have to use a thrust block in the center of the pumpkin between the two axles so you can do the axle end play adjustment. This is fine as long as you don't remove one of the axles because when you do the fluid will pull the thrust block out from where it is and it will land in the bottom of the housing. I don't know if there is a way to get it back from there to where it belongs without removing the pumpkin. Anyway that is my story. Good luck with your rear axle.
I got one of the early Tru Tracs and it did make a little noise. I ran into a guy at Carlisle who builds rear axles and he told me the early ones were known to be noisy. The Eaton Tru Tracs you get today are quieter. He told me to run a thicker oil in my rear and it should quiet it down. I just got done with taking out the pumpkin and cleaning out all the old oil. At my age of 59 this is not getting an easier (I don't have a lift). With the help of friend we also replaced the axle bearings. I am not sure if it was the new bearings or the thicker oil but my rear doesn't make any more noise. The guy at Carlisle (I forget his name) had a brand new pumpkin with 3.73 gears and a SG for $1500. Maybe the case wasn't brand new but it looked new. My firend bought that for his Dart. The guy said he could have sold a dozen of them. the one disadvantage of the Tru Trac is (if you are running the factory tapered bearings) you have to use a thrust block in the center of the pumpkin between the two axles so you can do the axle end play adjustment. This is fine as long as you don't remove one of the axles because when you do the fluid will pull the thrust block out from where it is and it will land in the bottom of the housing. I don't know if there is a way to get it back from there to where it belongs without removing the pumpkin. Anyway that is my story. Good luck with your rear axle.
Cuda360-4
Well-Known Member
I had 3.91 open diff and all it did was spin one tire. It was horrible. You had to come off the line so gentle for it to not spin that it lost too much time. I know you said you don’t mind the revs, but I always felt like I needed to shift it one more time. It drove me nuts. I switched to 3.54 and a limited slip and now it’s fantastic. If I really want to light them up it will burn both, and it’s actually much faster because there is no babying involved when pulling out.
540HemiCuda
Member
Rather than pull the center out to change oil, just drill a hole in the bottom of the housing. Then tap it and put a pipe plug in. I usually drill a little hole at first with a towel there to reduce or eliminate the mess on the drill, then drill it to size after it has drained. The housing is thin so I drill on the seam which is a little thicker. ALL of my diff housings have drain plugs.
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