Thursday, April 23, 2009

Swapping a 2-Piece Drive Shaft for a 1-Piece in a 1983-1997 Ford Ranger

Extended cab Ford Rangers* up through the 1997 model year use a 2-piece drive shaft to connect the transmission to rear axle. In 1998, Ford replaced the 2-piece shaft with a single shaft of either steel or aluminum.

*1994 and newer Mazda B-Series trucks are mechanically identical to Ford Rangers, therefore driveshafts are interchangeable and the procedure would be the same.

Anatomy of a Drive Shaft
Before I get started, perhaps it would help if I did a quick explanation of the parts of the drive shaft.This diagram shows the drive shafts arranged so that the front is on the right and the rear of the shafts are on the left. The slip yoke slides into the transmission on two wheel drive vehicles. 4x4 vehicles have a flange that bolts onto the transfer case. The U-joints allow the drive shaft to flex and move as the vehicle's suspension travels up and down. The rear flange bolts onto the pinion flange which comes out of the rear differential (the large "pumpkin" shaped thing you see on the rear axles of trucks). The carrier bearing connects the front and aft shafts on 2-piece drive shafts.

Why and When Would You Want to Swap the Factory 2-Piece Drive Shaft for a 1-Piece?
In stock form, the 2-piece drive shaft functions without problem, however there is an extra u-joint and carrier bearing which adds to the drive line maintenance.

The 2-piece's main shortcoming is that it does not lend itself to non-stock suspension heights. Adding even a slight suspension lift kit or lowering the suspension will cause the drive shaft to vibrate at certain speeds which is not only incredibly annoying, it can also lead to premature u-joint and carrier bearing failure. This drawing I made illustrates the cause of the vibration:As you can see in the picture, in stock form, the line between the transmission and the rear differential (hidden behind the rear tire in the picture) is straight, as indicated by the red line. When the vehicle's suspension is raised, the transmission (large silver object in picture) and carrier bearing (light blue object that connects the fore shaft and rear shaft) are also raised because they are connected to the vehicle's frame. This takes the driveline out from the straight line and causes the u-joints on the drive shaft to operate at extreme angles. This in turn causes a vibration that usually occurs at very slow speeds and highway speeds.

There are two possible corrections for this problem.
1. Lower the carrier bearing. By dropping the carrier bearing, you can help restore the proper angle of the drive line. However, it is impossible to completely remove the vibration because the front and back of the 2-piece drive shaft will never be in phase with each other.
2. Replace the 2-piece drive shaft with a single piece. You have two options within this option: get a custom drive shaft made at high expense, or find a used drive shaft from a newer Ranger, usually at a very reasonable rate.

It may seem like #1 would be easier, but swapping out the entire drive shaft is no more work. I have done both with my truck and would highly recommend skipping the hassle you will face trying to fine tune the carrier bearing height and go straight for the drive shaft swap.

Which Drive Shaft Can I Use?
All 1998 and newer Rangers* with the extended cab (sometimes called supercab) come with a single piece driveshaft, however, you will need to get the right one. The easiest way is to match up the specifications of your truck with the donor truck. These criteria will need to be fulfilled in order to get a good match:
  • Same drive train: 4x4 or 4x2?
  • Same transmission type: Automatic transmission or manual?
If your truck is a 4x4, it will not matter what type of transmission the donor truck has because the driveshaft attaches to the transfer case.

Note: 1983-1989 Rangers use a smaller flange on the rear axle. You will need to swap the rear u-joint section with one from the front of the shaft.

Note: If you get a drive shaft from a 4x4 with the aluminum drive shaft, it will have a larger transfer case flange and you will either need to swap in a smaller u-joint unit from the rear of the shaft (the exact opposite of what you need to do in the 1983-1989 note) or swap the flange on the transfer case.

You may ask where you can find a suitable drive shaft for the swap. Your best bet is a junkyard. You may also have luck searching online used car part sites (e-junkyards), online auction sites, or classified sections of online Ranger forums (there are several good ones). I purchased mine off a fellow member of a Ranger forum at a decent price.

There are two types of drive shafts available: steel and aluminum. I first thought all the shafts from 4x4s were steel and all from 4x2s were aluminum, but that is not entirely true, some of the newer 4x4s have aluminum shafts and I have heard of a few rare instances of 4x2s with steel shafts. It really boils down to availability and personal preference.

What Else Will I Need To Swap Drive Shafts?
The only tool you will need to swap the drive shafts is a 12mm 12-point socket and ratchet. Unfortunately, that is not all that needs to be done. Remember that carrier bearing on your old drive shaft? It is attached to a frame cross member. That cross member must be removed too, and that is no easy task.
So, besides the socket for the drive shaft you will need an angle grinder with metal cutting/grinding wheel, a punch and heavy hammer.

Before You Remove the Drive Shaft
You will want to set the parking brake and block the wheels before removing the drive shaft. Having the transmission in Park will do nothing once the drive shaft is removed since the transmission will no longer be attached to the wheels.

Removing the Carrier Bearing Cross Member
The first step is perhaps the hardest: freeing the frame cross member that supports the carrier bearing. The cross member is held onto the frame with two large rivets on either end. In addition to the rivets, each end of the cross member has a tab that sticks through a small slot in the side of the frame.Here you see a cross section of the frame where the cross member is riveted on. The yellow piece is the frame rail, the green section is the cross member, and the red part is a rivet. The green arrow points to the cross member tab that sticks through a slot cut in the frame. The red arrow points out the head of the rivet.

Start by grinding the rivet head off. Hold the grinder so that the sparks fly away from the vehicle since the gas tank is nearby. If you need to, improvise a spark shield out of cardboard or some other suitable material to place between where you are grinding and the gas tank.

When the rivet head has been completely ground off you need to take your metal punch, a stout metal bar, or some other suitable tool and use a heavy hammer to punch the rivet up and out of the hole. Repeat for the second rivet on the side you are working on, then move to the other side of the cross member and remove those two rivets.

On 4x4 models, you will also need to remove the gas tank skid plate.

With the rivets removed, you will need to remove the tabs from the ends of the cross member. I used the grinder to remove as much of the metal as I could from end of the tab protruding through the frame, then used a chisel and hammer and pounded the rest of the tab back, bending it and getting it free from the slot in the frame rail. Alternatively, you could cut the cross member in two and then slide each end out.

When the cross member is free it should just be resting on the inside of the frame. Our attention now moves to the carrier bearing. It is mounted onto the cross member by two bolts. Remove those bolts.

Position a jack stand under the carrier bearing because once we remove the cross member, the bearing will not be supported. You will have to rotate the cross member in order to get it completely free and off the vehicle. Exhaust and fuel system components may be in the way. With a little work, the cross member should come out. With the cross member out, support the carrier bearing with the jack stand.

Note: This cross member's only function is to support the carrier bearing, therefore it is safe to completely remove the cross member and discard it.

Removing the Drive Shaft
The dive shaft is attached at the rear differential flange by bolts. You will need a 12-point 12mm socket or wrench to remove the bolts. Once all the bolts are removed, the rear of the driveshaft should come loose. If it is still stuck on the flange (which it very well might be), try giving it a few light blows with a rubber mallet. Just be careful to not damage the mounting surface on the differential side.

When the rear of the drive shaft is loose, slowly pull the front of the drive shaft (the slip yoke) out of the transmission (4x2 models) or unbolt the front flange from the transfer case (4x4 models). The old 2-piece drive shaft should now be free from the vehicle!

Installing the "New" Drive Shaft
Before you install the new shaft, lubricate the teeth in the slip yoke with a little grease. Also notice that there is one tooth missing, this is for indexing purposes. If you look at the transmission you will see how the slip yoke (front of the driveshaft) needs to be orientated to slip into the transmission. Now is also a good time to inspect the transmission seal and replace if needed (if it is leaking transmission fluid out of the output shaft - where you will be inserting the drive shaft).

Orientate the drive shaft slip yoke with the transmission and insert it. If it does not want to go in, slowly turn the slip yoke until the indexing teeth match up. Slide the drive shaft slip yoke in slowly until you can bring the rear of the drive shaft up and rest it against the differential flange.

With the rear flanges lined up, reinstall the 12mm 12-point bolts. Tighten the bolts a little at a time to even out the pressure, like when you tighten wheel lug nuts. Fully tighten them to 85 ft. lbs.

Release the parking brake and remove the wheel blocks.

And there you have it, a nice solid 1-piece drive shaft!


Some Additional Notes:
I got a lot of the information, especially concerning the 4x4 instructions, from this site. Many thanks to that article's author.

You can also see how I originally went about lowering the carrier bearing before I decided to simply swap drive shafts by reading this carrier bearing relocation article here.

I can also say that there were no clearance issues for me using an aluminum drive shaft in a 2wd truck. Some people say you may have to modify the floor boards or lower the transmission to accommodate the aluminum shaft's larger diameter, but that is not true.

Apart from removing the carrier bearing cross member, this was an easy and affordable swap that has completely eliminated the drive line vibrations I was having after lifting the truck.

5 comments:

Anonymous said...

thanx. I'm gonna do this when i find another shaft.

Anonymous said...

Hey ever one I found the drive shaft for those out there looking got mine from a junk yard its a DANA part # 921065-6002 are F87A-4602-PB this is for the 4x2 super cab ranger automatic trans hope this helps

Anonymous said...

Nice guide! I'll be sure to keep this in mind. Thanks!

Anonymous said...

you dont have to remove cross member. just the mid shaft bearing pedastal.

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