'75 J-20 service truck

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jaber
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Location: Chino Valley, Az.

Re: '75 J-20 service truck

Postby jaber » Sun Aug 26, 2018 9:23 pm

Not yet, still need the vents for the dash and the hose kit to get it in. I've been running my butt off this summer and have not even got it mapped out yet. I know, shame on me...
I do have to say that I've been running this truck daily and with 17 mpg and the conversations I've been having, for my use, it's one of the best decisions I've made. Only problem I've had lately is keeping tires under it... :-bd
Jeff

'46 cj3a
'51 Willys p/u
'51 Willys Parkway Conversion
'74 CJ5
'75 J-20 Wrecker
'75 J-20 Cummins service truck
'77 J-10 p/u
'79 Cherokee
'88 Grand Wagoneer
http://s252.photobucket.com/albums/hh14/jeffaber/

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tedlovesjeeps71
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Re: '75 J-20 service truck

Postby tedlovesjeeps71 » Sun Aug 26, 2018 9:55 pm

jaber wrote:My trans kept leaving little drips under the rear aluminum case and the last couple weeks it turned into small puddles. Found a cast replacement on Ebay for $85 shipped and no more worrying about its fluid level. Did the seals in t case while it was out. Also found it already has a 5th gear lock nut, so that's another worry off my mind...

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Did you use a gasket or rtv for the new housing? I ordered the same thing for my scrambler. Haven't had time to install it yet.

Also, I read that some/many of these steel housings had bad bores. Not sure if that issue ever got resolved but it's worth reading up on.

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jaber
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Re: '75 J-20 service truck

Postby jaber » Mon Aug 27, 2018 5:52 am

Oh sure, NOW you tell me about the bad bores...
So far so good, no gasket, just black rtv. It's nice pulling into a customer's drive and not leave a mark.
My problem is that I've done too much reading on the NV4500. It's a medium duty trans in a heavy duty application. I found a thread on one of the Dodge forums that talks about finding an SAE#2 rear engine adapter and putting an Eaton/ Fuller 6 spd into it that will handle 500k be for needing repairs. Heres the thread if you have a couple days to read...

https://www.cumminsforum.com/forum/98-5 ... uller.html
Jeff

'46 cj3a
'51 Willys p/u
'51 Willys Parkway Conversion
'74 CJ5
'75 J-20 Wrecker
'75 J-20 Cummins service truck
'77 J-10 p/u
'79 Cherokee
'88 Grand Wagoneer
http://s252.photobucket.com/albums/hh14/jeffaber/

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tedlovesjeeps71
Posts: 2467
Joined: Fri Jul 22, 2016 4:39 pm

Re: '75 J-20 service truck

Postby tedlovesjeeps71 » Mon Aug 27, 2018 8:42 am

jaber wrote:Oh sure, NOW you tell me about the bad bores...
So far so good, no gasket, just black rtv. It's nice pulling into a customer's drive and not leave a mark.
My problem is that I've done too much reading on the NV4500. It's a medium duty trans in a heavy duty application. I found a thread on one of the Dodge forums that talks about finding an SAE#2 rear engine adapter and putting an Eaton/ Fuller 6 spd into it that will handle 500k be for needing repairs. Heres the thread if you have a couple days to read...

https://www.cumminsforum.com/forum/98-5 ... uller.html


Sowwy.

I think the 4500 is a good transmission. It has flaws but those can be addressed. My understanding is the lost 5th gear usually reared its head when people towed very heavily and used the cruise control often. The load/unload events caused the shaft to hourglass, the nut to loosen then fall off, and the. 5th gear would slip out of position. Hard to fix a previously "used" that is already showing signs but a fresh build and the "fix" installed should do the trick.
Next n line is often the 5600 but cost, size, and weight make that a hard choice.
I read some on the Clark conversion too. It sounds good. Finding one and living with the wider shift pattern where the biggest complaints.

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jaber
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Location: Chino Valley, Az.

Re: '75 J-20 service truck

Postby jaber » Mon Aug 27, 2018 2:35 pm

It was nice to see the aftermarket 5th gear nut already on mine when I switched the cover. Makes for mo re piece of mind...
My understanding is that the 5600 is notorious for snapping output shafts...
Jeff

'46 cj3a
'51 Willys p/u
'51 Willys Parkway Conversion
'74 CJ5
'75 J-20 Wrecker
'75 J-20 Cummins service truck
'77 J-10 p/u
'79 Cherokee
'88 Grand Wagoneer
http://s252.photobucket.com/albums/hh14/jeffaber/

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tedlovesjeeps71
Posts: 2467
Joined: Fri Jul 22, 2016 4:39 pm

Re: '75 J-20 service truck

Postby tedlovesjeeps71 » Mon Aug 27, 2018 2:50 pm

jaber wrote:It was nice to see the aftermarket 5th gear nut already on mine when I switched the cover. Makes for mo re piece of mind...
My understanding is that the 5600 is notorious for snapping output shafts...


Not saying it isn't true... I'd just be curious as to the conditions that cause it to snap. There's more than a lot of guys running turned up Cummins towing crazy heavy stuff. IMHO, if your rolling 800^ tq and towing 20k+ and lose a shaft... It's kinda a "duh" result. These trucks are powerful. It's easy to forget how much stress is put on components when you set your programmer to kill and the stereo to loud.

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jaber
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Location: Chino Valley, Az.

Re: '75 J-20 service truck

Postby jaber » Mon Aug 27, 2018 3:00 pm

Sooo, what are you sayin bout me... :D :D :D :evil:
Jeff

'46 cj3a
'51 Willys p/u
'51 Willys Parkway Conversion
'74 CJ5
'75 J-20 Wrecker
'75 J-20 Cummins service truck
'77 J-10 p/u
'79 Cherokee
'88 Grand Wagoneer
http://s252.photobucket.com/albums/hh14/jeffaber/

User avatar
tedlovesjeeps71
Posts: 2467
Joined: Fri Jul 22, 2016 4:39 pm

Re: '75 J-20 service truck

Postby tedlovesjeeps71 » Mon Aug 27, 2018 3:02 pm

jaber wrote:Sooo, what are you sayin bout me... :D :D :D :evil:


Turn it up and get crunked!

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jaber
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Posts: 2971
Joined: Sat Aug 27, 2011 5:24 pm
Location: Chino Valley, Az.

Re: '75 J-20 service truck

Postby jaber » Mon Aug 27, 2018 3:10 pm

I guess i just feel that the ujoints should be the weakest link, like in old school trucks...
I'll be watching for parts, got a couple friends in the tow business. I have a couple other builds I need to do before I get too excited with this one. It's doing it's job better then I thought and that makes it all worth it. Getting to know it well enough to float the gears, helping to make the clutch last longer. Just rolled 261k...
Jeff

'46 cj3a
'51 Willys p/u
'51 Willys Parkway Conversion
'74 CJ5
'75 J-20 Wrecker
'75 J-20 Cummins service truck
'77 J-10 p/u
'79 Cherokee
'88 Grand Wagoneer
http://s252.photobucket.com/albums/hh14/jeffaber/


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