Prior to stuffing a 600+ hp gen 3 hemi in my drag car Duster I’m going to first change the 8 3/4 diff. The 8 3/4 is living on borrowed time as it is with 1.45 second 60’ times even with the crappy 410 LA motor. I’d like to use a D60 instead of a 9” since the price for one ready to roll is about the same. And of course I’d rather stick to mopar tradition than sell out to the 9” crowd. Has anyone had experience with a Moser D60? What do they weigh compared to the 8 3/4?
Moser 60
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I have a (older) Moser D60 in my car. Running slightly faster 60' times than you, but have had zero issues. I know the D60 is heavier than a comparable 9 inch but I would go with the D60.
Locomotion
Well-Known Member
I was confident enough in the Dana 60 efficiency that I got 2 from Moser. One is in my Aspen Wagon that I planned on high 11's and low 12's with high 1.50 60' times. I got another for my Dart Sport which has a best 60' of 1.47 footbraking and detuned to consistent low-mid 1.50's with a 360. Has most of the better options with a 4.88 Pro gear, but it's not installed in the car. (Too bad you're not closer, but gear might be more than you need anyway.) If you have the correct gear, I see them as basically install and forget about it, besides basic fluid changes and inspections, just to be safe. Cover makes it easy.
Also keep in mind that when some lightening options are added, it will bring the weight of a Dana 60 closer to an 8 3/4" because going from a SureGrip to a spool in a Dana 60 will save more weight than doing the same in an 8 3/4. Same with beveling the ring gear for weight savings. Normally you don't need additional bracing on a Dana 60 as well. Unfortunately, I don't recall the weight difference when I did the swap in the Aspen. But around 40 lbs may be the number in my case. I had to make up the difference by adding ballast per class requirements.
Also keep in mind that when some lightening options are added, it will bring the weight of a Dana 60 closer to an 8 3/4" because going from a SureGrip to a spool in a Dana 60 will save more weight than doing the same in an 8 3/4. Same with beveling the ring gear for weight savings. Normally you don't need additional bracing on a Dana 60 as well. Unfortunately, I don't recall the weight difference when I did the swap in the Aspen. But around 40 lbs may be the number in my case. I had to make up the difference by adding ballast per class requirements.
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Locomotion
Well-Known Member
Using the Wallace calculator for rpm with a 33" tall tire and 4.88 gears would still give more rpm than your plan with a 4.10 gear and a 28" tire. (Using a 100 mph reference, it still showed 51 rpm more.)
My Dart ran a 4.86 8 3/4" in it with 30" tall tires. But I buzzed it to almost 7,000 and went through the 1/4 about the same. (IHRA Crate Motor Stock - they went to an ET only format in 2018.) But I kept it detuned a tenth or two until I needed it for a heads-up race or to move up in qualifying.
Calculate GEAR, RPM, MPH, TIRE DIAMETER
Interesting to play with and useful for comparing changes. But it doesn't always provide accurate numbers, especially in more radical combos.
My Dart ran a 4.86 8 3/4" in it with 30" tall tires. But I buzzed it to almost 7,000 and went through the 1/4 about the same. (IHRA Crate Motor Stock - they went to an ET only format in 2018.) But I kept it detuned a tenth or two until I needed it for a heads-up race or to move up in qualifying.
Calculate GEAR, RPM, MPH, TIRE DIAMETER
Interesting to play with and useful for comparing changes. But it doesn't always provide accurate numbers, especially in more radical combos.
Both my LA 410 and a hemi stroker are fairly modest RPM engines especially running methanol. The LA peters out about 6400. Falls on its face with the 4.30s after the 1000’. Wasn’t a big deal racing 1/8 mile, but a majority of passes will be on a 1/4 now.
Locomotion
Well-Known Member
You have it figured out. Take advantage of the torque made by strokers. Basically like a big block. If 4.10 happens to be a bit too much, you can always go to a slightly taller tire too.
FYI/FWIW, taller tires will hook a bit better because they put a little more rubber on the track and running wider rims will allow you to run more air pressure while maintaining a wider footprint. i.e.: Many Stock class racers run 10" rims even though 9" wide tires are the limit. Radial slicks will usually be a little faster in ET and RT, but they are more sensitive to track conditions.
They also don't "grow" on the top end, which may affect the final gear choice.
Good luck!
FYI/FWIW, taller tires will hook a bit better because they put a little more rubber on the track and running wider rims will allow you to run more air pressure while maintaining a wider footprint. i.e.: Many Stock class racers run 10" rims even though 9" wide tires are the limit. Radial slicks will usually be a little faster in ET and RT, but they are more sensitive to track conditions.
They also don't "grow" on the top end, which may affect the final gear choice.
Good luck!
Locomotion
Well-Known Member
Shortened. Don't know the difference off hand but probably best to measure after the rear is in.
Locomotion
Well-Known Member
Do you have a 1350 end on the current driveshaft? Otherwise you'll have to (preferably over a conversion joint) change it to 1350 anyway because that the only yoke option Moser shows for the Dana 60.
Duane
Well-Known Member
Are you aware that the strange s60 and the moser 60 are not quite the same. The strange uses threaded carrier adjusters to set up backlash. The Moser does not. Also the area on the moser casting where the axle tubes are pressed in to the center section is shorter in length on the moser. In some applications the moser may have more room for say a wheelie bar bracket than the s60.
For me the threaded adjusters made me purchase the strange version. Also according to strangers website, the s60 is a thinner casting than the original factory Dana 60. They claim the s60 is now only 15 lbs heavier than a back braced 9 inch.
I decided to buy the Strange 60 over a moser. Prices are similar, and the S60 is lighter.
Does anyone know off hand what the spring perch center to center measurement on relocated springs is? Without pulling the axle off it looks like 35 5/8”. Also going to have them angle the pinion down 4 degrees for the caltracs.
Does anyone know off hand what the spring perch center to center measurement on relocated springs is? Without pulling the axle off it looks like 35 5/8”. Also going to have them angle the pinion down 4 degrees for the caltracs.
famous bob
mopar misfit
Question : did u notice a performance gain with the alum. driveshaft when u switched ??----------just curious if it was noticeable , and how much.--.001-.003 ?
I switched from the stock size driveshaft and stock U-joints to the larger aluminum shaft and 1350 joints. I didn’t gain or lose any time. The extra weight of the bigger joints evened out with the aluminum shaft I guess.
Duane
Well-Known Member
I decided to do the perches at home myself to make sure it's right and have a local fabricator weld them. I did not want to risk them screwing up the angle and the perch width.
Just me but that's how I am doing it. Once I know it's right, then off for powder coating.
I also just ordered one of these.
Should come out just under the back bumper at 48 inches.
(Training wheel lol)
Yeah I don’t quite qualify for one of those skateboard wheels yet. Maybe with the hemi it’ll need a set.
I did the relocation and perches myself a few years ago. Unfortunately I wasn’t thinking correctly, and put a 0* angle on my pinion. This time I want the pinion down 2 degrees at least. Was thinking of asking for 4 degrees, then shimming it back 2 if I need to. Those caltracs must rotate up a little bit under hard acceleration.
Don’t know how much power it takes to bend an 8 3/4 in a 3000 pound car, but I’ve got enough to do it. Not sure if you can tell by the picture, but the right tube is bent forward 11/16”. So bad I had to pry on the moser axle shaft pretty hard to get it out. A back brace is definitely a requirement. Doesn’t matter know anyway because my S60 finally showed up.
Best so far is 6.92 1/8, 11.008 1/4 at 6000’ DA.
Not really noticeable to me. I’m sure it’ll feel like a different car now. It was scrubbing the slicks pretty good, and the right side was rubbing on the quarter a bit. I didn’t plan on running the car at all this year with the bent housing, but the S60 took four months to show up.
Working on shortening the driveshaft. Right now as is there’s only about 1/2” in and out play at the yoke. Wanted to take an inch off the shaft giving me 1.5” slip yoke play. The splines on the yoke are 5.5” deep, which gives me 4” of splines engaged on the output shaft at rest.
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