14 Bolt Rear Open Conversion?

sandcobra164

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I watched a video on the Detroit Locker and it made me an expert. I'm being silly of course. What I can't figure out is a potential 1/2 revolution of the driveshaft at any speed over 10 mph would make on the synchros and their ability to do their job. 4.56 to 1 axle ratio, tracking, 31 inch tall tires, tracking, at 10 mph the driveshaft is turning over faster than your heart beats.
 

ken

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I swapped a SM465/NP205 into my first 1028. Back in 1994. It's still running and shifting fine to this day. Every once in a blue moon I have a HARD engagement at a red light. This is my off road toy CUCV and it lives a hard life. You might consider opening it up and inspecting it. I would bet it has some wore out parts. There may be rebuild parts available.
 

Corvette1974

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Yeah, I've done the swap a few times. Wish I had the parts I took out, I'd at a little boot and swap you. I'm one locker short here.

Oddly, I don't see the same issues you do. I have an SM465 in my truck. Have an NV4500 on the shelf waiting to go in. Hope it works out.
From what I gather and have experience, the SM465 is buttery to shift compared to my NV (and that seems to be the general consensus online, that the NV really isnt that smooth of a shifter).
I didn't notice any difference with my m1028 after the NV4500 swap. I'd say it's still more well behaved than the one in my other CUCV with the auto transmission.
The locker in my truck with the TH400 was pretty much not an issue. With the manual it is awful. Also every once and a while the locker will either partially engage or something and it will let out a bang/slip that literally feels/sounds like a u joint just vaporized. Not good.
Interesting thread, the locker does add significant play to rear driveline, so it makes sense it could affect shifting with a manual.

I'll just add that I've noticed variation in the behavior of the locker in different trucks, all with original TH 400. Of course the way they act varies with load, but even in bone stock, empty 1008s and 1028s, I notice variations in levels of cornering chirp & hop, and how often they adjust themselves(the "clank", for lack of a better word). Whether this is a function of wear or something else, I do not know.

I wonder if differences in shifting styles adds another variation.
I've tried all sorts of shifting styles, basically every other vehicle in my life is a manual. ZF5, ZF6, BW Super T10, Mack 9 speed, tractors, etc. They all shift smoother than the NV. You are right about the play and difference truck to truck. I think with the auto there isnt a problem because there is never any driveline slack as with a manual.

I have to wonder what your backlash is on the truck. Also, have you lifted it? (Pinion angle, springs)
Stock truck - Unknown, but the truck drives fine and doesnt make any noises. I could check it if you think that would make that much of a difference. I've changed the fluid before and it was clean.
 

Corvette1974

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I watched a video on the Detroit Locker and it made me an expert. I'm being silly of course. What I can't figure out is a potential 1/2 revolution of the driveshaft at any speed over 10 mph would make on the synchros and their ability to do their job. 4.56 to 1 axle ratio, tracking, 31 inch tall tires, tracking, at 10 mph the driveshaft is turning over faster than your heart beats.
There is certainly some crazy stuff happening back there. And the NV is also not in a place it was really meant to be. I could be wrong but I'm pretty sure that a GMT400 truck couldnt be ordered with such a "rough" combo on the trans.
 

Corvette1974

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I swapped a SM465/NP205 into my first 1028. Back in 1994. It's still running and shifting fine to this day. Every once in a blue moon I have a HARD engagement at a red light. This is my off road toy CUCV and it lives a hard life. You might consider opening it up and inspecting it. I would bet it has some wore out parts. There may be rebuild parts available.
The SM is without question a stronger transmission and better shifter than the NV. Longer throw yes, no overdrive, but better for HD use. I mean our 1947 dodge 2.5 ton with the synchro trans out of a 1951 Dodge shifts better than the NV, in fact it has some of the smoothest shifts I've ever felt. Youre talking old school big brass synchros vs modern small carbon fiber/fiber synchros. Tech is cool, but nothing beats out heavy metal. The NV was purpose built for an application in a computer controlled time, the SM was a development upon the previous 80 years of truck transmission history (SM420, T19, etc) That is my .02
 

Recovry4x4

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From what I gather and have experience, the SM465 is buttery to shift compared to my NV (and that seems to be the general consensus online, that the NV really isnt that smooth of a shifter).
I've sure had my shares of SM420s, SM465s and T18s. I've heard a lot of folks describe the shifting of an SM465 and buttery was never a word used. I have an NV4500 in the garage and I can say with certainty that between my NV and every SM I've ever owned, in or out of the truck, no SM shifted as smooth as that 4500. Maybe once in the truck it will get ugly but not on the shop floor.
 

Corvette1974

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I've sure had my shares of SM420s, SM465s and T18s. I've heard a lot of folks describe the shifting of an SM465 and buttery was never a word used. I have an NV4500 in the garage and I can say with certainty that between my NV and every SM I've ever owned, in or out of the truck, no SM shifted as smooth as that 4500. Maybe once in the truck it will get ugly but not on the shop floor.
Hahaha! Maybe buttery isnt the word but I probably just prefer the shifting of other transmissions such as the SM. The NV4500 install was mostly done for OD, otherwise I would have done an SM. Would have been cheaper too.
 

WARWAG

Active member
I swapped a SM465/NP205 into my first 1028. Back in 1994. It's still running and shifting fine to this day. Every once in a blue moon I have a HARD engagement at a red light. This is my off road toy CUCV and it lives a hard life. You might consider opening it up and inspecting it. I would bet it has some wore out parts. There may be rebuild parts available.
Are you double clutching?
 

WARWAG

Active member
Back in high school I had a girl friend who's parents owned the True Value Hardware store in Pacific Grove. One day Her and her friend drove the True Value flatbed delivery truck out to my home in Carmel Valley. There were many a stop light in between those two points. That poor SM465 lol. They picked me up and asked me to drive as they were having a hard time shifting it. When I was able to shift the truck without grinding the gears they were very surprised and impressed LOL. I grew up driving Old trucks and took my drivers test in a chevy with a SM465. What a great transmission. You just need to know how to message her into gear. The best Combo we had was a SM465 with a Ranger Gear Splitting Over drive. That and we had a twin stick NP205 made for quite the busy transmission tunnel which my girlfriends hated lol. Shifting both sticks required a bit of a dance that was fun to master. Great memories. That Ranger Overdrive gear splitter gave us a .73 over drive. If I ever get another 4x4 with a SM465 I would to throw in a Ranger and twin stick that NP205 and run a Magnum box. The 159 crawl ratio would be insane. Sorry for the rant.
 

Corvette1974

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Are you double clutching?
I have tried both double clutching and normal clutching. It can/can not make a difference. It is very up in the air. And I've tested clutch disengagement - lifted rear axle off the ground and in gear the wheels dont spin until the clutch is let out the normal amount. You can even put the Tcase in neutral and rev it in gear and quickly shift it and there is no problem. Only when moving and when the situation is right/wrong does it not shift well.
 

Corvette1974

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Back in high school I had a girl friend who's parents owned the True Value Hardware store in Pacific Grove. One day Her and her friend drove the True Value flatbed delivery truck out to my home in Carmel Valley. There were many a stop light in between those two points. That poor SM465 lol. They picked me up and asked me to drive as they were having a hard time shifting it. When I was able to shift the truck without grinding the gears they were very surprised and impressed LOL. I grew up driving Old trucks and took my drivers test in a chevy with a SM465. What a great transmission. You just need to know how to message her into gear. The best Combo we had was a SM465 with a Ranger Gear Splitting Over drive. That and we had a twin stick NP205 made for quite the busy transmission tunnel which my girlfriends hated lol. Shifting both sticks required a bit of a dance that was fun to master. Great memories. That Ranger Overdrive gear splitter gave us a .73 over drive. If I ever get another 4x4 with a SM465 I would to throw in a Ranger and twin stick that NP205 and run a Magnum box. The 159 crawl ratio would be insane. Sorry for the rant.
Thanks for the very cool story! Sounds like a sweet setup indeed... I'd definitely look into doing that on a truck that already had an SM465.

-Will
 

Corvette1974

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Sounds like you might need a rebuild. Getting worn inside. How many miles on the trans?
Supposedly 19k miles on it. Interesting thought. I might convert the axle to open (regardless, itll give it better manners) and then if the NV really needs a rebuild I'll have to cross that bridge. Otherwise, I'm gonna give it He** until that time, I dont drive the truck that much.
The Ranger over drive is 6" or so long. I think Advanced Adapters sells them now.
Good to know...
 

Corvette1974

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Newly rebuilt SM465 go around the $650 range. Not bad at all really.
Definitely not bad, but then I have to also get the Ranger which looks to be $1500ish. I'm going to have to balance rebuilding the NV myself vs paying vs SM, etc.

Going to try the locker thing first, regardless.

-Will
 

Corvette1974

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Long term update! I finally got around to installing my new gears to match the NV4500 conversion. I actually ended up keeping the locker and glad I did. The 3.73s absolutely transformed the truck. It solved all locker problems with the lurching and crazy banging and the trucks gearing is very "OEM like". Transmission shifts very well now that it isnt dealing with 4.56 nonsense. It drives like it always should have from the factory/if it was a factory truck back in the day. I'd highly recommend changing out the gears to 3.73s with the NV4500. Also seems to have no loss of capability, just hauled a car on a trailer more effectively than before because instead of being in 5th/OD you are in 4th which is better anyway...

-Will
 
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