The Great Pumpkin - '71 Duster
There was nothing really wrong with the rear end in and of itself and it actually worked fine. The only issue was a leaking pinion seal from the 489 case and it was starting to make a mess. Other than that, all was good.
I've had a set of Moser axles and an MP aluminum 4.10 geared diff. that I built several years ago sitting on a shelf that I've been wanting to put to use. I also got a complete Caltrac set up that I'm really stoked about, so out came the entire rear end.
Cleaning it up was not in my initial plans but I figured since I'm redoing all the brake lines and putting in a new suspension, it should probably come out. I removed all the old brake stuff, pulled the pumpkin out and pulled the axles out. The springs and 489 diff. were put on the shelf. The bare housing was sandblasted clean and painted.
Originally the car had the MP offset shackle kit. The front hangers need to be trimmed to allow full movement of the Calvert triangulated pivot. I started grinding on them and removed a lot of material which I was a little uneasy about. I did the left side first and did a trial fit with the mono springs which come with aluminum bushings. The front eye was binding and I needed to really pull the spring towards the center of the car to get it to line up with the shackle. I knew that couldn't be good but it went in.
I started on the right side but halfway through my first cut, I realized I had the hanger upside down and was cutting material off the wrong part. Doh! I abandoned that project and ordered a new offset shackle kit from Dr. Diff. They arrived really quickly and are WAY nicer and much lighter than the old MP ones. I ended up only having to cut a notch on the inside of the triangulated pivot to allow the full range of motion when the pivot swings forward. Calvert said it was OK to do as long as it was kept to a minimum. Seems like a good idea for someone to make these for this particular application so you're not grinding the nice shiny finish off your new Caltracs. Oh well.
The axles that were on the car were the OE small bolt pattern. The flange holes had been welded up and re drilled for the large bolt pattern. They had green bearings installed and were in good condition. The axle seals were fine. There are super long ARP 12 point screw in studs which I transferred to the Mosers. Nice!
I hit a small snag when doing the rear brakes. I thought I could re-use the backing plates that were on the car but I didn't realize there was a difference in 10" backing plates. Turns out there are specific plates for 1.75" shoes and 2.5" shoes - the pivot on top is a different height due to the mounting points of the shoes. I had all new 10 x 2.5" brake stuff on the shelf but it wouldn't go together with the small shoe backing plate. Live and learn. I found a set on here which were cleaned up and installed. Everything went together perfectly after that.
I still need to finish the install on the rear. I gotta trim the right side Caltrac pivot and then torque everything down. I also have to put in some new fluid but then it should be ready to go.
Here are some pics of the housing. I will post more pics when I get to it, especially of the Caltrac pivot.
Housing blasted clean, ready for paint.
Here's the old 489 case with the 4.30 gears. No more snubber with the Calvert stuff.
Here is some of the hardware soaking in Evaporust. Rear hangers, parking brake levers etc. Don't laugh at my pink hospital bucket.
Here's a pic of the Moser axles. Note the long studs on the one axle. They come with studs but you take those out and install your preferred ones. I had them install green bearings.
Here's the housing after being primed. I installed an empty case when it was blasted to prevent media getting inside. I cleaned it thoroughly afterwards anyway.
Painted. Just a semi gloss with a flat clear. Naturally it chipped when I put it back under the car but I can touch it up.
Here is the cool guy aluminum diff. I think its one of the very first ones Mopar made. I bought it almost ten years ago at this point. The price on these has gone up several hundred bucks since then and I'm not sure if they're even available anymore. I think the 4.10 should be a good gear for the car. The p.o. raced the 1/8 mile. We talked about gears and he seemed to think the 4.10 would be better for a 1/4 mile track which is what I would mostly be racing on. That's a Victory billet 7290 yoke.
Case torqued down to housing. Easier to do out of the car.
Here is one of the ill-fated MP offset front spring hangers. I was not feeling good about removing so much material but I did it anyway. Turned out to be all for naught. One of the studs was loose too so I was happy to ditch these boat anchors. Probably should have done that from the git-go.
More to come.
There was nothing really wrong with the rear end in and of itself and it actually worked fine. The only issue was a leaking pinion seal from the 489 case and it was starting to make a mess. Other than that, all was good.
I've had a set of Moser axles and an MP aluminum 4.10 geared diff. that I built several years ago sitting on a shelf that I've been wanting to put to use. I also got a complete Caltrac set up that I'm really stoked about, so out came the entire rear end.
Cleaning it up was not in my initial plans but I figured since I'm redoing all the brake lines and putting in a new suspension, it should probably come out. I removed all the old brake stuff, pulled the pumpkin out and pulled the axles out. The springs and 489 diff. were put on the shelf. The bare housing was sandblasted clean and painted.
Originally the car had the MP offset shackle kit. The front hangers need to be trimmed to allow full movement of the Calvert triangulated pivot. I started grinding on them and removed a lot of material which I was a little uneasy about. I did the left side first and did a trial fit with the mono springs which come with aluminum bushings. The front eye was binding and I needed to really pull the spring towards the center of the car to get it to line up with the shackle. I knew that couldn't be good but it went in.
I started on the right side but halfway through my first cut, I realized I had the hanger upside down and was cutting material off the wrong part. Doh! I abandoned that project and ordered a new offset shackle kit from Dr. Diff. They arrived really quickly and are WAY nicer and much lighter than the old MP ones. I ended up only having to cut a notch on the inside of the triangulated pivot to allow the full range of motion when the pivot swings forward. Calvert said it was OK to do as long as it was kept to a minimum. Seems like a good idea for someone to make these for this particular application so you're not grinding the nice shiny finish off your new Caltracs. Oh well.
The axles that were on the car were the OE small bolt pattern. The flange holes had been welded up and re drilled for the large bolt pattern. They had green bearings installed and were in good condition. The axle seals were fine. There are super long ARP 12 point screw in studs which I transferred to the Mosers. Nice!
I hit a small snag when doing the rear brakes. I thought I could re-use the backing plates that were on the car but I didn't realize there was a difference in 10" backing plates. Turns out there are specific plates for 1.75" shoes and 2.5" shoes - the pivot on top is a different height due to the mounting points of the shoes. I had all new 10 x 2.5" brake stuff on the shelf but it wouldn't go together with the small shoe backing plate. Live and learn. I found a set on here which were cleaned up and installed. Everything went together perfectly after that.
I still need to finish the install on the rear. I gotta trim the right side Caltrac pivot and then torque everything down. I also have to put in some new fluid but then it should be ready to go.
Here are some pics of the housing. I will post more pics when I get to it, especially of the Caltrac pivot.
Housing blasted clean, ready for paint.
Here's the old 489 case with the 4.30 gears. No more snubber with the Calvert stuff.
Here is some of the hardware soaking in Evaporust. Rear hangers, parking brake levers etc. Don't laugh at my pink hospital bucket.
Here's a pic of the Moser axles. Note the long studs on the one axle. They come with studs but you take those out and install your preferred ones. I had them install green bearings.
Here's the housing after being primed. I installed an empty case when it was blasted to prevent media getting inside. I cleaned it thoroughly afterwards anyway.
Painted. Just a semi gloss with a flat clear. Naturally it chipped when I put it back under the car but I can touch it up.
Here is the cool guy aluminum diff. I think its one of the very first ones Mopar made. I bought it almost ten years ago at this point. The price on these has gone up several hundred bucks since then and I'm not sure if they're even available anymore. I think the 4.10 should be a good gear for the car. The p.o. raced the 1/8 mile. We talked about gears and he seemed to think the 4.10 would be better for a 1/4 mile track which is what I would mostly be racing on. That's a Victory billet 7290 yoke.
Case torqued down to housing. Easier to do out of the car.
Here is one of the ill-fated MP offset front spring hangers. I was not feeling good about removing so much material but I did it anyway. Turned out to be all for naught. One of the studs was loose too so I was happy to ditch these boat anchors. Probably should have done that from the git-go.
More to come.
