Narrowing down driveline selection;

[cleefurd]

• 6BT
• NV4500 (for the .73 OD)
• NP205 (divorced) 3:1 low
• Ouverson 2.5 Rockwells w/4.9:1 Ring-sets
• Michelin 365/80 R20 (43.1" dia 65MPH rated)

This should put engine RPM around 1870 during 65MPH cruise.
The Michelins considered are designed for 11" rims, so these aren't too far off at 10J (whatever that means) http://cgi.ebay.com/ebaymotors/New-2...item2ea481f499

I just need to figure out what WMS to WMS disc brake converted Rockwells will mesh these wheels with 7" backspacing to match up well with the M715's frame rails and fender flares.

[Roy]

The "J" refers to the bead configuration and type.

[cleefurd]

Thanks Roy.
I called around today looking for a set of Rockwells. Waiting for some callbacks.
I have learned to look for Spicer type. Beyond that I suspect they'll be completely rebuilt with the gear set (4.9:1) sought.

[Barrman]

Not trying to argue, but a 205 has a 1.98:1 ratio in low. Unless you are spending the big bucks get all new gears inside.

What do you mean by "Spicer type" Rockwell axles? The old ones were actually made by Spicer and had what someone with a front wheel drive car would call CV joints in the front axle. The later ones, 1958 and newer, have regular u joints for the front. There are two sizes of the newer style. Don't let someone sell you a bunch of high priced parts that won't work together.

Are you going to run thim hub in our out?

[cleefurd]

Can't recall the builder but yes, it is an NP205 rebuilt with 3:1 low. They had a picture (should have written down the name) of an Atlas gear next to it, as well as a standard 205 gear, and the mod was much more substantial.

The Rockwells I read to buy were the U-joint type, rather than CV type.

I've read to flip the hubs around to match the steer axle. As I understand I need the single rear axle to match wheel back-spacing after the flip-around. Sorry if I seem confused, I'm figuring this out quick so I can buy right the first time. Also trying to figure out how narrow I have to cut them yet still clear the frame rails with the tire/wheel combo I'm looking at, while not going too wide beyond the flares.

Found a guy who is trying to round up a set to from Tennessee down to Andalusia AL on Mother's Day for $1500. That's not too far a drive to pick up from Pensacola.

[cleefurd]

Not trying to argue, but a 205 has a 1.98:1 ratio in low. Unless you are spending the big bucks get all new gears inside.

Yes Barrman you got it;
http://www.jbconversions.com/product...mpletecase.php
Pretty excited about finalizing the overall powertrain, money burning hole in pocket...

Would the NV4500, NP205 described, and re-ringed 4.9:1 Rockwells all be compatible??? Can the NP205 I'm eying readily interface the NV4500 to the selected axles (with adaptive yokes) and is the trans/T-case pairing ideal for the 6BT?

Once I decide.... no going back.

Main goals are

• useful low range (hence 3:1 low-range to compliment 43" tires) and;
• NV4500's .73 OD for modest highway RPM's (1870 RPM @ 65MPH)

.

[defbob]

The Lomax is ONLY for Chevy mated transfercases. You'll have to bolt it to the NV4500. I am not sure if they are making the gears anymore or they are waiting for enough orders to have a new batch made.

[Barrman]

I don't think you are going to need any shortening for the Rockwells. I went home and looked at my Gasser axles. Timken made them, not Spicer at the beginning. Sorry for the bad info.

Big ujoint style is what you want for parts availability. CV type for pulse free full lock turning under power.

I would really suggest a married NV4500/NP205 combo. You loose 2 ujoints, a cross member and gain parts found all over the country.

How much lift are you going with? I ask because every single Rockwelled M715 I have ever seen has oil pan clearance issues above the front chunk. That was with gas engines. The 6BT is bigger.

[syzygy]

Hey Cleefurd, Sounds like a fun build, especially with money burning holes in your pockets. Can't wait to see it unfold.

Not sure what you're using to do your RPM/speed calculations but before I actually saw that you had an RPM stated in your last post I did my own and I came up with numbers a little off from yours. Probably not big enough to make a difference, but I'll attach a screen shot of the spreadsheet I use in case it's helpful.



In case it's not self-evident, I basically wanted to know what idle, peak torque, and redline speeds would be in each gear in both high and low range, so the interesting data is at the right side of the screen.

Then I added a few target speeds for cruising to see what the RPM would be... those are at the bottom.

Also, not sure if you've seen the Canadian build up !!! thread... you might be able to glean some info on what to/not to do there.

P.S. If anyone wants a copy of the spreadsheet, PM me with your email address and I'd be happy to send it along. Hopefully I did all the calculations right

[glenn]

Look at Kamikazee12volt build to get an idea of what works on a 715 with rockwells and a 6bt. He has a very good build thread on his rig. There are a couple other guys building rockwell 715's right now too but his is done and he did it fairly quickly.