84-92 4bt swap

[Ramcharger90]

So im looking for an 84-92 extended cab 4x4 so I can 4bt Cummins swap it and solid axle swap.

So far I have the the 31 spline 8.8

I want to make a list in this thread on the parts I need to get still,
Then turn this into a build thread.

84-92 Ranger extended cab
4bt
Zf5
Np205

Front axle im open to suggestions I was thinking Wagoner dana 44 but they are just as hard to find as a EB dana 44 it seems in Pa.

So with that said I know some of you have been there done that.

I want to go with 33's so im looking for a road and off road friendly gear ratio. This truck will be a winter/weekend here and there truck. But if I want to drive an hour or so away be able too.

 

[2drxploder]

fullsize axles under a ranger make a tank!

 

[franklin2]

How high does the 4bt rev out to and make it's peak torque? That and your tire size is going to determine your gear ratios.

 

[scotts90ranger]

If you are doing a SAS without any stock drivetrain, there's no reason you need to start with a 4x4 truck... unless you need the boxed frame ahead of the engine crossmember on the passenger side, that's about the only difference that could matter.

Agreed, with 33's you're probably going to want tall gears if the 4BT is anything like the 6BT in engine speeds... but 3.73's would probably be fine.

 

[Ramcharger90]

If you are doing a SAS without any stock drivetrain, there's no reason you need to start with a 4x4 truck... unless you need the boxed frame ahead of the engine crossmember on the passenger side, that's about the only difference that could matter.

Agreed, with 33's you're probably going to want tall gears if the 4BT is anything like the 6BT in engine speeds... but 3.73's would probably be fine.

According to Ford the frames from a 1990 4x4 and rwd have different part numbers. Whether or not there is no difference in the actual frame rail in terms of pitch or shape I couldn't tell you or not. I was gonna box the frame anyway either way I need an extended cab first I found a decent frame but the body is wasted. That 8.8 has 3.73 lsd already

 

[RonD]

4BT does max torque at 1,600rpm, max HP at 2,300rpm, so gearing is essential

Stock governor is set for 2,800rpm but fuel starts to be cut at about 2,500rpm, you can change the governor spring to raise this
The 4BT is only balanced for about 3,000rpm

 

[Snoranger]

You want your cruise rpm at 1700-2000 rpm. Any higher and you’re sacrificing engine life and fuel economy drops like a rock. Have a zf5 and a US Gear overdrive to put behind my 4bt.

 

[Ramcharger90]

I have access to plenty of 2wd rangers so if there is no difference in the frame I am open to converting a 2wd extended cab

 

[Ramcharger90]

@bobbywalter

What is this actual difference between the 2 frames from 4x4 to 2wd? Im planning on doing a sas swap.

 

[scotts90ranger]

The difference in frames is engine crossmember for stock suspension pivot brackets and the boxing of the passenger side frame rail in front of the engine crossmember. Some people get (or got, not common anymore) crazy and swap engine crossmembers and make theirs 4x4 with stock stuff, with your plans I wouldn't bother trying to find a stock 4x4... There's other little differences, but nothing to get crazy about, one isn't inherently stronger than the other

 

[RonD]

Well you are taking out a 450lbs engine and putting in a 750lbs engine, that right there would be reason enough to strength the front frame, lol

You need to measure 5 times and weld once when you add the front axle mounts.
Close don't count
You need 4 wheel alignment

 

[Ramcharger90]

About 10 years ago or more I remember helping a friend do a solid axle swap from a early bronco. We made the frame rail into swiss cheese where the radius arms mounted. I remember we used revolver shackles in the back other than it flexing damn good not much else.

 

[Ramcharger90]

The difference in frames is engine crossmember for stock suspension pivot brackets and the boxing of the passenger side frame rail in front of the engine crossmember. Some people get (or got, not common anymore) crazy and swap engine crossmembers and make theirs 4x4 with stock stuff, with your plans I wouldn't bother trying to find a stock 4x4... There's other little differences, but nothing to get crazy about, one isn't inherently stronger than the other

I wasn't sure.

 

[scotts90ranger]

I understand, I've gleaned a lot from people in the last 20 years from back before I had a 4x4 and lusted over different ideas... I've forgot a LOT but I remember some little odd things

I COMPLETELY understand the want of an extended cab... that's why my new daily driver is extended cab... I would have liked a '89-92 but OBD II and low miles is nice

 

[Ramcharger90]

Got my 88 today

The interior is disgusting but has power windows.

Frame seems solid.