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Author Topic: Monroe conversion t-case adapter? Or 4x4 tranny?  (Read 9490 times)

BluntBear

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Monroe conversion t-case adapter? Or 4x4 tranny?
« on: December 17, 2010, 03:55:22 PM »
This may be just a shot in the dark, but I thought I'd throw it out there.

How was the Monroe 4x4 conversion pulled off at the t-case? Did they somehow fit an adapter to the 4L80E 2x4 housing to accommodate a transfer case? Was the 2x4 4L80E swapped with a 4x4 4L80E? I'm curious! I'm also curious which t-case was used, I've heard rumor of an NP205, which makes sense, but again, curious.   

Also, are the 4x4 4L80E tranny mounts the same as the 2x4 tranny? Can a swap be done without customizing or finding cross members and such.

Thanks.
Being prepared just let's us know how unprepared we really are.

Raymo

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Re: Monroe conversion t-case adapter? Or 4x4 tranny?
« Reply #1 on: December 17, 2010, 07:00:36 PM »
I've seen a few HD 4x4's converted a few different ways.

It's been done with a divorced NP205, A Dodge NP205 with a cut coupler that was 32 spline at the trans and 29 at the case, and a 4401/4470 case normally found in LD 3500's.

It really all depends on what axle you use and what side the differential is on. A Dodge Dana 60 will match right up to the HD leaf spring spacing. It's what I'm using under my HD currently. But my problem is the 7" I gained with the conversion, and I'm working on lowering it currently.

In my opinion, a divorced case would be ideal because you could retain the VSS and parking brake already on the truck.

EDIT: To answer the trans question, if a married transfer case was used, then a 4x4 trans was used, and in my experience with the dozens of LD solid axle swaps I have done, a 4x4 mount has two studs to mount to the crossmember, where as most 2wd's used only 1. But there are A FEW different mount and crossmember configurations that I have seen.
« Last Edit: December 17, 2010, 07:10:44 PM by Raymo »
'94 3500-HD, Cummins, Getrag, NP205. Shortend rear frame with a Pickup Bed. Dana 60 front, stock 80 rear.

'03 2500-HD 8.1 and Allison

BluntBear

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Re: Monroe conversion t-case adapter? Or 4x4 tranny?
« Reply #2 on: December 18, 2010, 01:51:23 AM »
Ok, so you're saying if I use a divorced NP205, and make or have made a custom coupler to connect the tranny to the t-case, and retain the existing parking brake, that's the most efficient way? That makes sense...

 Did you use the stock radius arms for your front axle conversion, meaning did you weld new brackets on the D60, or do something else. Also how did you deal with steering?

I'm weighing the options because I have property in Canada with a 2 mile dirt road (translation: mud road) that I need to access on a regular basis starting next summer. The road is bad, and I do mean bad. I've almost been stuck every time on the road with my 3500 4x4, granted lockers would fix that, but the goal is to haul logs for a log home onto the property, hence the 3500HD flatbed. I know for a fact I'd get stranded in a 3500HD 2x4 with a load. So I'm looking to haul 4 tons consistently over this road and a 4x4 will be essential, so if a divorced NP205 can handle that much weight, then you're right, that'd be the best course of action. But I'm gonna be maxing out the 15,000lb vehicle weight over mud and I'm not positive an NP205 would hold up, if I'm wrong please tell me so I can sleep at night.

I need something dependable because it's north BC territory and where the property is I'm an hour from civilization and 1/2 hour from the closest neighbor. It must be stout and trustworthy, no crawling, no abuse, just weight and mud.

My first instinct was to convert it to a NP4500 and attach an NP271, adapt the parking brake and final drive axle assembly, and fit a D70 from Boyce equipment. That would require a lot of work and time, but would it be worth it?  Because If I can go with a divorced NP205 and a D60 that'd be great, and cheaper. Been a mechanic for 11 years now but never branched out to the 4x4 truck world until now. I've got the skills but just need some help with the technicalities.

Lastly, Raymo, why are you having problems with the 7" lift. Is it the drive angles, vibration? I'm curious what lowering would accomplish, thanks.
Being prepared just let's us know how unprepared we really are.

Raymo

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Re: Monroe conversion t-case adapter? Or 4x4 tranny?
« Reply #3 on: December 18, 2010, 10:51:40 AM »
Well I'm hell bent on lowering it because getting in and out is a major PITA.  ;D

I left the HD leaf springs and simply slid the King Pin Dana 60 under the front, simple and fast. I used a Crossover steering arm to the passenger side knuckle for the steering. You can see how my truck sits in my build thread in the projects area.

An NP205 would live fine under those conditions. If you use a passenger drop axle (Chevy or Dodge) then keep your eyes out for a 32 spline 205. It will have 32 spline input and output shafts, which are strongest, and accept a 32 spline 1410 yoke to match what the HD has now. Then you'd still have to build a tranfercase crossmember.

Keep in mind, athough this is the simplest bolt up, finding a 32 spline divorced 205 will be a chore. I have a few divorced 205's but they're 30 spline, and there are no useable yokes available. I could change them over but need the bore for the input bearing bored .375".

Which ever way you go will NOT be cheap.
'94 3500-HD, Cummins, Getrag, NP205. Shortend rear frame with a Pickup Bed. Dana 60 front, stock 80 rear.

'03 2500-HD 8.1 and Allison

Raymo

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Re: Monroe conversion t-case adapter? Or 4x4 tranny?
« Reply #4 on: December 18, 2010, 11:04:20 AM »
Given your needs for the truck, and to try and avoid much headache I would personally go with this set up;

Swap the 2wd AUTO for a 4wd with the Borg Warner 4401 from a light duty 3500, get the 4401 that has a FIXED YOKE. Shouldn't be a problem as I've had and serviced a bunch. This will let you retain "Park" since you will have a hell of a time fitting the driveline brake to the 4401, and will handle the load if driven sensibly.

Get a '78-'79 FORD Dana 60, This is the ONLY FACTORY DRIVERS SIDE DROP axle that will slide under the HD and match up with the 4401 transfer case. Any driveshaft shop worth a whoot can make a driveshaft to mate the front axle.

To level my truck I used a 4" block made for a Super Duty, it's 3" wide to match the spring. Most other blocks are 2.5".

You mentioned the 271 case, and that would be the ultimate in beef, but not nessisary unless you want to seriously abuse the truck, but from the sound of it, you should be just fine with a 4401 or an NP205
« Last Edit: December 18, 2010, 11:53:54 AM by Raymo »
'94 3500-HD, Cummins, Getrag, NP205. Shortend rear frame with a Pickup Bed. Dana 60 front, stock 80 rear.

'03 2500-HD 8.1 and Allison

plasticbadger

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Re: Monroe conversion t-case adapter? Or 4x4 tranny?
« Reply #5 on: December 19, 2010, 01:06:44 PM »
My 4x4 3500HD uses a 4L80E (standard 2WD spec) with a custom fabricated tail shaft and a Borg Warner 4407 with parking brake on the rear output. The front axle is a custom built Drivers drop Dana 70.

I have the stripped HD next to a regular K3500 dually and reckon that swapping in the 4WD 4L80E complete with 4401 from this would be a good way to go, but it has the rear slip yoke and as Raymo says it would be a PITA to fit a parking brake. If you can find a fixed yoke 4401 I reckon a Land Rover parking brake could be made to fit, or maybe add some parking brake calipers to the rear disks (Wilwood make some).

You can see the fabricated tail shaft housing, transfer case and parking brake in this shot:

2000 3500HD 6.5TD 4x4 ex-armoured car - the Worlds only RHD 4x4 3500HD?

Raymo

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Re: Monroe conversion t-case adapter? Or 4x4 tranny?
« Reply #6 on: December 19, 2010, 01:22:39 PM »
That's a great picture of the overall setup!

With your 120" wheel base, and the length of that drivetrain, that has got to be one short rear driveshaft!  :o
'94 3500-HD, Cummins, Getrag, NP205. Shortend rear frame with a Pickup Bed. Dana 60 front, stock 80 rear.

'03 2500-HD 8.1 and Allison

ED-NY

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Re: Monroe conversion t-case adapter? Or 4x4 tranny?
« Reply #7 on: December 19, 2010, 02:16:18 PM »
plasticbadger

Are you going to have it done in time for the Royal Wedding on April 29, 2011 at Westminster Abbey ;D

Ed

FYI: That's all I hear about on TV over here, they can't tell us when the US economy is going to improve but....

plasticbadger

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Re: Monroe conversion t-case adapter? Or 4x4 tranny?
« Reply #8 on: December 20, 2010, 03:02:42 AM »
Yep, that's my goal, not really for the wedding, but my wife isn't working weekends through Jan/Feb/Mar so that's my window to get it done. We don't hear much on the royal wedding over here, more about the Euro and US economy, so maybe watch the UK news, though at the moment it's all about the weather we're having. In 12 years of living on the South Coast we've had less snow than we've had this year alone.

Raymo, the rear drive shaft is about 18" long, one of the reasons for stretching the wheelbase back out to 138" during the rebuild. The front shaft is pretty short too and uses a CV at the transfer case end.

PS. there's quite a few of these set ups for sale in the UK at the moment as many of these trucks were parted out for their engines. If anybody is looking for an axle set and transmission I could look at some shipping prices.
« Last Edit: December 20, 2010, 03:09:24 AM by plasticbadger »
2000 3500HD 6.5TD 4x4 ex-armoured car - the Worlds only RHD 4x4 3500HD?

BluntBear

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Re: Monroe conversion t-case adapter? Or 4x4 tranny?
« Reply #9 on: December 22, 2010, 09:14:14 PM »
Ok, now I'm confused.

It's my understanding that not all 4l80E's have a 15000# GVWR, so if I were to swap my 2x4 version with a 4x4 the chances are it'll have a 9000# GVWR? It stands to reason that if I'll actually be moving 15000#, then shouldn't the drive-line reflect that capacity? That's the reason I was even looking at the NP271 t-case, it's the only reasonable option with a GVWR high enough to reflect a 3500HD's ability.

I was also wondering if anyone has ever mounted a divorced case behind the parking brake drum? Would it work if you went straight from the parking brake drum output yoke to a 1410 yoke t-case input ? Then it'd just be a matter of shortening the drive-shaft before and drive-line center bearing, and mounting the case. Should work in theory, right? Or just wishful thinking?
Being prepared just let's us know how unprepared we really are.

Raymo

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Re: Monroe conversion t-case adapter? Or 4x4 tranny?
« Reply #10 on: December 22, 2010, 11:31:06 PM »
Only difference in transmissions is a driveline brake provision, because of the disc brakes out back. The key to keeping the trans and case alive in the heavy trucks is the crazy low gearing. The more "work" the differential does, the less stress is put on the driveline to turn it. Only way to keep a slushbox of any kind alive, is to keep the fluid cool. Take the extra precaution of installing a trans temp guage. You can have the baddest Allison transmission on the block, but it's as useless as a 700-R4 if overheated.

And you're right on track, the trans doesn't care what it turns behind it, as long as the driveline angle is matched to avoid vibration or possible galling of the u-joint if it's run with no angle. Just be sure there's enough room for the short shaft to be collapsed for installation.

And if the case were to be set up 1410, it's imperative to get the 32 spline unit, as it's the only case that has a yoke that big available.
'94 3500-HD, Cummins, Getrag, NP205. Shortend rear frame with a Pickup Bed. Dana 60 front, stock 80 rear.

'03 2500-HD 8.1 and Allison

BluntBear

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Re: Monroe conversion t-case adapter? Or 4x4 tranny?
« Reply #11 on: December 23, 2010, 01:47:17 PM »
Great info Raymo, and everyone else. thanks
 
Being prepared just let's us know how unprepared we really are.

 


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