Dana S60...TrueTrac, Spool, or Detroit Locker which one?

**pajeff02** · 03-04-2014, 08:22 AM

I think the stock axles are 28 spline, while the Moser axles are 33 spline. Quite a difference in their heft too:

**98TransAmWs-6** · 03-04-2014, 09:10 AM

Originally Posted by pajeff02

I think the stock axles are 28 spline, while the Moser axles are 33 spline. Quite a difference in their heft too:

For the 12 bolt the only choice for a wavetrac is a 35 spline or 33 on the 9" I believe. Anyone know what a good gear ratio in a 9" would be for an automatic?

**SMWS6TA** · 03-04-2014, 09:39 AM

3.75 is close enough to the 3.73 gears you were looking for. I'm using 4.10's but it's also a M6.

**98TransAmWs-6** · 03-04-2014, 09:52 AM

Originally Posted by SMWS6TA

3.75 is close enough to the 3.73 gears you were looking for. I'm using 4.10's but it's also a M6.

Figured as much. I guess I'll be saving for a 9" wavetrac to drop $3600 on it. That is what it priced out to lol. Wonder if I could buy it in pieces to avoid dropping so much at once.

**SMWS6TA** · 03-04-2014, 09:55 AM

shipping will add more to the cost over time.

**SMWS6TA** · 03-04-2014, 09:58 AM

check these guys out also

Welcome to Midwest Chassis, Inc. - Home

**Firebirdjones** · 03-04-2014, 10:09 AM

Originally Posted by SMWS6TA

Will the WAVETRAC are between $995 (9in) to $1095 (8.8) if not ordered with a new rear. I know because that is what I'm going to once I break the one in the 8.8 rear.

Having been in a Trans Am with a 9" and a WAVETRAC, it was fun as hell when he launched at 5800 rpm. If I didn't have the seat belts on I think I would have been in the t-top storage area. Lifting a fat boy like myself out of the seat says something.

Here is the info on WAVETRAC Diff's:

Funny they don't compare that at all to the good ole' clutch style posi unit, because ironically, they do the same thing

. They apply power to both wheels all the time, even if one is in the air or on a slippery surface. That's why all your old muscle cars that had the optional posi unit always had the trunk sticker warning about jacking up the rear and running the car if you still had one tire touching the ground,,,,,because the sucker would take off on you

**Firebirdjones** · 03-04-2014, 10:17 AM

Originally Posted by 98TransAmWs-6

Okay so I am definitely going wavetrac. The question is 12 bolt or 9". I have an a4 so I was going to go with a 12 bolt for the 3.73 gears which I can't get in a 9", only 3.75 but I could just do 4.10 I guess as well since I can get that in either.

Is one better for an automatic over the other? I have just seen if m6 people tend to get the 9" and if a4 they get the 12 bolt so I am wondering what the reasoning is.

There is none, other than the 9" offers many more options, it's been retrofitted into any car you can imagine, they are cheap to build, so it's naturally become a popular choice.

I don't buy into the whole 9" for stick and 12 bolt for auto thing either. Not sure how or why that started but people have been using 12 bolts behind stick cars (including OEM applications) since the GM 12 bolt was invented in 1965. I've run them in heavy wheel yanking stick cars without a problem, and have them in 5 different cars here including my wifes 6 speed 4th gen

However nothing at all wrong with a 9", I run those too, you have more gear choices, 3rd member swaps are a snap, and they are a stout piece when built with good parts. If there is any drawback it's that they sap a little HP, and they are a bit heavier. Neither are much consequence when you consider the entire book of options you can get with one. You can run a 3.70 gear in that 9" too, close enough to your 3.73 goal.

**Firebirdjones** · 03-04-2014, 10:23 AM

Originally Posted by 98TransAmWs-6

For the 12 bolt the only choice for a wavetrac is a 35 spline or 33 on the 9" I believe. Anyone know what a good gear ratio in a 9" would be for an automatic?

33 spline is more than enough, especially for an auto. A good gear ratio would soley depend on your engine power curve. For best 1/4 mile performance pick a gear ratio and tire height that allows you to cross the finish just above your peak shift rpm, just above peak HP.

For peaky engines that like 7,000 rpm and a 28" tire, you are most likely looking at alot of rear gear (4.30-4.56) give or take more or less depending on the combo.

Seems most of your stock LS1's like something in the 3.70 range because they run out of steam at 6,000 and most people still run the short 26" tire as well.

**98TransAmWs-6** · 03-04-2014, 10:38 AM

Originally Posted by Firebirdjones

Originally Posted by 98TransAmWs-6

For the 12 bolt the only choice for a wavetrac is a 35 spline or 33 on the 9" I believe. Anyone know what a good gear ratio in a 9" would be for an automatic?

33 spline is more than enough, especially for an auto. A good gear ratio would soley depend on your engine power curve. For best 1/4 mile performance pick a gear ratio and tire height that allows you to cross the finish just above your peak shift rpm, just above peak HP.

For peaky engines that like 7,000 rpm and a 28" tire, you are most likely looking at alot of rear gear (4.30-4.56) give or take more or less depending on the combo.

Seems most of your stock LS1's like something in the 3.70 range because they run out of steam at 6,000 and most people still run the short 26" tire as well.

Not sure what my power curve looks like yet but my cam is designed to spin into the 7k area, since road racing is the primary use here with some drag and street. So maybe I'll want a 4.30+ gear then?

For the 9" it is actually 31 or 35 spline I misspoke earlier.

**Firebirdjones** · 03-04-2014, 11:01 AM

Originally Posted by 98TransAmWs-6

Not sure what my power curve looks like yet but my cam is designed to spin into the 7k area, since road racing is the primary use here with some drag and street. So maybe I'll want a 4.30+ gear then?

For the 9" it is actually 31 or 35 spline I misspoke earlier.

Depends on whether you really want to put more emphasis on drag racing or not. There is always compromise to be made with a street car. I'd hate to give advice on a gear for a car primarily meant for road racing because tracks vary so much. You might like that 9" for it's 3rd member swapability then.

Are you switching over to a stick? Usually auto isn't the first choice for a road race car.

**SMWS6TA** · 03-04-2014, 11:12 AM

^^this is why I like it when FBJ posts. I feel like I'm a student in a class room with a great instructor that explains the reason why you do stuff not just the how.

**98TransAmWs-6** · 03-04-2014, 11:17 AM

Originally Posted by Firebirdjones

Originally Posted by 98TransAmWs-6

Not sure what my power curve looks like yet but my cam is designed to spin into the 7k area, since road racing is the primary use here with some drag and street. So maybe I'll want a 4.30+ gear then?

For the 9" it is actually 31 or 35 spline I misspoke earlier.

Depends on whether you really want to put more emphasis on drag racing or not. There is always compromise to be made with a street car. I'd hate to give advice on a gear for a car primarily meant for road racing because tracks vary so much. You might like that 9" for it's 3rd member swapability then.

Are you switching over to a stick? Usually auto isn't the first choice for a road race car.

Down the road I will be doing a m6 swap yes. Maybe a gear that would be reasonably good for both but obviously not the best so I am not exactly stuck with one without doing horribly. Like I said my drag racing will be pretty much to just test mods out for quarter mile times and such.

What is a 3rd member? Sorry for the noob question I just am not familiar with that term.

**Firebirdjones** · 03-04-2014, 11:21 AM

Originally Posted by SMWS6TA

^^this is why I like it when FBJ posts. I feel like I'm a student in a class room with a great instructor that explains the reason why you do stuff not just the how.

Thanks for the kind words

**Firebirdjones** · 03-04-2014, 11:34 AM

Originally Posted by 98TransAmWs-6

Down the road I will be doing a m6 swap yes. Maybe a gear that would be reasonably good for both but obviously not the best so I am not exactly stuck with one without doing horribly. Like I said my drag racing will be pretty much to just test mods out for quarter mile times and such.

What is a 3rd member? Sorry for the noob question I just am not familiar with that term.

If that's the case, I'd definately do what these guys suggested and just go with a nice all around 3.70 gear and see how you like it. The 3rd member is the pumpkin that drops out of a 9" as one assembly with your posi and gears setup in one piece. What's nice, if you don't mind the extra expense, is to have another 3rd member setup with a different gear of your choice to experiment with, or one you are more comfortable with on the street, and one for track day or ??? I do that sometimes myself.
If it makes you feel any better, when I installed the 12 bolt in my wifes 4th gen (which is a 6 speed) I installed 3.73 gears. Doesn't sound like much of a jump from the 3.42's but quite frankly they work very nice with the T56 with a very noticable difference in performance. When stomping the throttle in first gear (not popping the clutch) it went from hooking and going with 3.42's, to hazing the tires and fish tailing with 3.73's. First couple of times caught me by surprise and I ended up banging the rev limiter at 6700 before I could snap second gear. It rapped that quick.
To make you feel more comfortable, I had 4.10's in the 12 bolt first. Frankly, I loved it, 1st and second gear were almost useless = lots of fun

. However being my wifes daily driver, at the time she was buzzing down to Phoenix (200 mile round trip) for work everyday, and although the cruise RPM wasn't bad with a .50 overdrive, I found she was cruising 80-85 mph (speed limit 75 here) to shorten the trip time, pushing the car harder than I would have myself. So I dropped it to 3.73's. She no longer runs on the highway with the car (works just up the street now) so it's all stop and go driving, but the 3.73's will stay. Nice all around gear and made stop and go driving a bit more enjoyable.

**SMWS6TA** · 03-04-2014, 11:49 AM

So FBJ, when I finally get all my crap back in your saying with the 4.10 gears in the 8.8, I'm not going to use 1st at the track anymore, correct?

**98TransAmWs-6** · 03-04-2014, 12:23 PM

Originally Posted by Firebirdjones

Originally Posted by 98TransAmWs-6

Down the road I will be doing a m6 swap yes. Maybe a gear that would be reasonably good for both but obviously not the best so I am not exactly stuck with one without doing horribly. Like I said my drag racing will be pretty much to just test mods out for quarter mile times and such.

What is a 3rd member? Sorry for the noob question I just am not familiar with that term.

If that's the case, I'd definately do what these guys suggested and just go with a nice all around 3.70 gear and see how you like it. The 3rd member is the pumpkin that drops out of a 9" as one assembly with your posi and gears setup in one piece. What's nice, if you don't mind the extra expense, is to have another 3rd member setup with a different gear of your choice to experiment with, or one you are more comfortable with on the street, and one for track day or ??? I do that sometimes myself.
If it makes you feel any better, when I installed the 12 bolt in my wifes 4th gen (which is a 6 speed) I installed 3.73 gears. Doesn't sound like much of a jump from the 3.42's but quite frankly they work very nice with the T56 with a very noticable difference in performance. When stomping the throttle in first gear (not popping the clutch) it went from hooking and going with 3.42's, to hazing the tires and fish tailing with 3.73's. First couple of times caught me by surprise and I ended up banging the rev limiter at 6700 before I could snap second gear. It rapped that quick.
To make you feel more comfortable, I had 4.10's in the 12 bolt first. Frankly, I loved it, 1st and second gear were almost useless = lots of fun

. However being my wifes daily driver, at the time she was buzzing down to Phoenix (200 mile round trip) for work everyday, and although the cruise RPM wasn't bad with a .50 overdrive, I found she was cruising 80-85 mph (speed limit 75 here) to shorten the trip time, pushing the car harder than I would have myself. So I dropped it to 3.73's. She no longer runs on the highway with the car (works just up the street now) so it's all stop and go driving, but the 3.73's will stay. Nice all around gear and made stop and go driving a bit more enjoyable.

Wow that is cool you can just pop it right out and switch another in. Maybe down the road I'll get a 3rd member set up for drag and one for road racing and I'll just swap in whatever I am doing. So a 9" with a wavetrac and a 31 spline and 3.75 gears it is. Another question what exactly is a back brace and what does it do? I mean I have an idea though, I probably can't run one anyways with Kooks TDs I will be running.

**Firebirdjones** · 03-04-2014, 01:53 PM

Originally Posted by SMWS6TA

So FBJ, when I finally get all my crap back in your saying with the 4.10 gears in the 8.8, I'm not going to use 1st at the track anymore, correct?

Ha, you'll be using first gear for sure, especially at the track, just be ready to yank the lever

Not sure on your tire height, but I run the stock size 275/40-17 on my wifes car which is only 26". With the 4.10, and a 2.66 1st gear, it was pretty short and would just blow the tires off, couldn't even make it accross the intersection before 1st was done. A 28" tire would work nicely.

It reminded me of (but not quite as bad) as a fox body 5.0 with 3.73's and the 3.35 first gear they have in the T-5, you talk about a short first gear, but a whole lot of fun

My ventura is the same way with a 2.54 first gear muncie and 4.88's.

**Firebirdjones** · 03-04-2014, 01:55 PM

Originally Posted by 98TransAmWs-6

Wow that is cool you can just pop it right out and switch another in. Maybe down the road I'll get a 3rd member set up for drag and one for road racing and I'll just swap in whatever I am doing. So a 9" with a wavetrac and a 31 spline and 3.75 gears it is. Another question what exactly is a back brace and what does it do? I mean I have an idea though, I probably can't run one anyways with Kooks TDs I will be running.

A back brace is to keep the axle tubes from flexing/bending forward during extremely hard launches. Not really necessary for anything but the really serious.

**35th-ANV-SS** · 03-04-2014, 03:37 PM

All solid advice. Will - I have a 4.11 gear in my M6 with the 31-spline axles. 4.11 is funner than shit in 1st, especially with the Procharger. The car takes off like a rocket on a nice, hot summer day where the tires are sticky. However, you need to be VERY quick on the shift to 2nd.