29 Pickup Rear Axle Issue

M

ModelAHawaii

Junior Member
Hi,

My 29 pickup has no forward or reverse gears.

I lifted the rear axle on jack stands. Opened the fill hole on the of the center carrier banjo. When I spin the motor by hand the pinion gear and spider gears and the right axle (pass. side) spin. The left axle (drivers side0 does nothing.

I had my son spin the motor while I locked the carrier in the banjo. Nothing moved. I I believe everything from the engine to the drive shaft is good. When I try to spin the drivers side wheel nothing at all spins in the carrier. The pinion gear spider nothing.

I've pulled the hubs the axle keys are still good on both sides.

Is the drivers side with the large pinion gear the drive side of the rear axle?

If I have no foward or reverse gears does that mean the axle gear is broken or????

Are the rear axle halves with the gear one solid piece each? Again I'm the third owner so I don't know if anything has been done to the rear axle previously. However, where the original axle half solid one piece with the gear?

I've been trying for some time to isolate the issue of the now movement and seem to always come back the the rear axle.

Does anyone sell rebuild rear axles? Just drop in. I live in the middle of the ocean and don't really have anyone locally that works on the Model A's. I've been just doing most things myself since I purchased the pickup but this one has stumped me.

Any assistance would be appreciated.

Thank you!
 
I broke an axle on my 29 pickup many years ago. I remember it as being fairly simple to replace. I don't remember the details. You will have to take the rear end apart. The biggest issue is that it is heavy, too heavy for me to lift at my age. You have your son to help. Consult the red book, Model A Ford Mechanic's Handbook, Volume I. You can just set it up on saw horses to start.

The vendors have new axles which I would recommend rather than an old one, unless the old one is in excellent condition. Shipping cost to Hawaii will be expensive. See https://www.snydersantiqueauto.com/product.htm?pid=978126&cat=41627
 
Last edited:
It could be a broken axle but it's easy to check that. Just pull on each wheel and a busted one will come off the hub with whatever is left of the axle still attached to the hub. It could be a broken transmission main shaft too.

Normally, turning one side through the spider gears will result in the other side rotating in a different direction but a lot depends on condition of the bearings, the spider gears, the pinion gear on the drive shaft, and/or the condition of the U-joint. A sheared key on the pinion can cause a no drive situation. A broken U-joint can also cause the same. Broken gear teeth would be another cause.

The whole carrier drive unit comes out the left side with the bell removed but the axle has to be disassembled to do that. It's best to support the rear frame and body on stands and pull the whole rear drive out in one assembly to get to everything easily.
 
Last edited:
Thank you for the replies.

From the engine back I believe everything is ok. I can spin the motor and it trucks the transmission and gears. The u joint spins the drive shaft back thru the drive shaft to the pinion gear. The pinion gears spins the spider gears which spin the axle gear on the right side ONLY. The left side has NO movement at all. When you manually lock the center carrier in the diff you can't spin the motor or transmission dears or drive shaft. This is why I believe from the front to the pinion its all ok. I have movement on the passenger side but nothing at the drivers side.

I have all of the Les Anders manuals and nothing says anything about this. I don't know if the rear axle has ever been worked on.

I just have no forward or reverse gear. Key ways are all good at the hubs. I'm guessing I have to pull the rear axle and open it up.

What special tools will I need to open the differential. I already bought the spring spreader.

Are the rear axle shafts with the gears a solid one piece or is the gear pressed on???
 
On original axles, the gear was forged with the axle. There were some replacements made with a gear welded onto the axle. I did repair a rear end that suffered a failure with one of the welded on axle gears. A poor aftermarket design.

John
 
My bet is that there is one of those poor axles with the welded on gear in there and the gear has separated from the axle.
I'd put the rear of the car on jack stands, take the tension off the spring with a spring spreader and with both hubs removed from the rear end (already done), undo the trumpet on the LHS and withdraw the axles and diff assembly. While it is in this state, it is easy to check the pinion. Assuming that is OK, the problem with the axle will be obvious. Carefully dismantle the diff assembly keeping the gaskets (their thickness is important). Les Andres' red book will be of great help to you here. Replace the mangled axle , assuming that is what you find, inspect all of the other components and reassemble. This might be a good time to put a set of bearings through it.
The job is fiddley and time consuming but once you have it done, your confidence in your ability will soar.
 
The most difficult part of the job is getting started. Once you dive into it things will be clear. As Synchro says, keep track of the gaskets so you don't loose adjustment. Les Andres' and other instructions go into much detail about adjusting the axle, but it you just replace the axle and keep track of the gaskets you don't have to do any adjusting. You can always check things if you want to be meticulous.
 
The pinion gear only turns the ring gear which is bolted solid to the carrier housing. The spider is also fixed to the carrier. If the ring is still bolted to the carrier well and the carrier assembly is still intact then the pinion will drive it. If there is a major problem with the spider or it's gears then it could lose drive. As mentioned previously, if there is a problem with one of the side gears on either axle and the spiders are intact then it could lose drive on the side that has the problem and the other side since there is nothing to hold the spider gears in check.
 
You must log in or register to reply here.
Back
Top