"Do I need a new transmission?"

August 18, 2008 10:34 AM

Have you ever had your car's axle stuck in the transmission? What did you do about it?

I drive a 2001 Kia Rio. The driver's side front axle is stuck in the transmission and, after taking it to a local mechanic and a national chain mechanic, I'm not sure if I should get a new transmission or just live with the clicking noise the car makes when I make hard turns. That what the national and local places told me are my options, respectively.

Both said this is rare. On the off-chance that any of you have had this issue, how'd you deal with it? Thanks.

posted by girlmightlive to travel & transportation (11 comments total)

This is the failure of a CV joint (the wobbly bit on the end of the axle that provides drive through different angles of the shaft) - it really doesn't need the transmission replacing, but it will certainly get worse with time. How much time and how much worse is impossible to predict, but at some stage it will seize and this may be a big issue. Replacing the transmission is so overkill as to be equivalent to replacing the car because you can't get the wheel off when you have a puncture.

If I read this correctly and you are suggesting that neither mechanic was capable of removing the axle, that blows my mind. Applications of various slide hammers, heat and proper splitting tools should have been no issue to remove that and these places should have had teh tools to do so. I assume you didn't get charged for the lack of removal?

And hell yes, it's rare. I'd take it to a Kia dealer with a prior quote request for changing the relevant joint, and then let them deal with it. It's unlikely it "just won't come out", it's more likely that it needs special tools and a bit of perseverance. If you have a quote for the hours involved first, they can't sting you, and if you request that they call you before replacing anything other than that which you have requested, you should be fine.

Just keeping driving it will risk a more 'exciting' failure later on, and is not really the best option. You should be fine for a decent while, but it is not necessarily something that will fail in a nice, predictable fashion.
posted by Brockles at 11:14 AM on August 18, 2008

The clickety noise when turning is certainly a CV joint going out. I am shocked that 2 places could not figure this out and replace them, as it is a fairly common practice since most drivers don't maintain the boots properly.

Take it some where they know what they are doing.
posted by internal at 11:45 AM on August 18, 2008

"Take it some where they know what they are doing."

Exactly. Some axles have clips inside the differential area of the transaxle which need to be removed before the axles will come out.
posted by gjc at 3:21 PM on August 18, 2008

As you already know, the clicking noise is the CV joint. Most cars now require replacing the whole axle, not just the CV joint, so your mechanic is correct that you need the axle replaced.

The stub shaft/axle being stuck in the transaxle is unusual and is usually the result of with sudden traction after spinning the wheels. This results in the stub shaft splines getting twisted. This twisting results in the stub shaft getting stuck in the transaxle. It may take an inordinate amount of force with slide hammers, heat, pulleys etc to remove.

This force may damage the transaxle/differential, and this is why your mechanics are saying you may need to replace the transaxle. This is a risk and the shop will write the estimate stating that the transaxle may be damaged during disassembly, and they are not liable for it.

I would not recommend doing any extensive driving with a failing CV joint. I would attempt to remove the stub shaft.
posted by Mag Plug at 5:58 PM on August 18, 2008

(note: The mechanics are prescribing a new transmission. Not a new shaft.)

Also, I'd be very surprised if a Kia Rio has enough power to spin the wheels more than a fleeting turn, never mind twist a spline within another. I think there is more (or more likely less) to this and it should be relatively easily remedied with the right tools. The age of the car suggests some corrosion or some other such damage.

A thought: Has the car been in an accident that involved that side of the front of the car? An impact such as a hard hit to the kerbs may produce difficult to remove driveshafts.
posted by Brockles at 6:07 PM on August 18, 2008

Wheel spin has little to do with the power of the engine. Wheel spin often happens when on ice or stuck in snow. Then there comes the sudden (stop) traction of dry pavement. This can allow the engine to be in the torque band that allows for maximum torque when the wheels stop. This twisting is more common on lower power set ups than high power engines as the high power engines can still spin the wheels on the dry pavement.

Transaxle is the same as a transmission but it includes the differential.
I have never seen a damaged transaxle from the axial loads coming from the side impact that didn't also crack the case.
posted by Mag Plug at 6:42 PM on August 18, 2008

Transaxle is the same as a transmission but it includes the differential

The mechanics are prescribing a new transmission (which is a gearbox and includes the differential in a FWD, as it is all in the same casting usually). They mean the whole damn gearbox asmbly, cos they can't get the shaft out, from what I can ascertain. A transaxle is the assembly of the gearbox and the driveshafts (axles). That is, surely you agree, massive overkill.

Then there comes the sudden (stop) traction of dry pavement. This can allow the engine to be in the torque band that allows for maximum torque when the wheels stop.

There must be traction and also a prevalence of power to distort the splines, or at the very least significant momentum change. I believe some old fella said something about "equal and opposite forces"? A low powered, small capacity engine would just stop spinning/spin the clutch/torque converter/stall/drop to idle, especially a car with such low levels of grip as a Kia. The momentum in the drivetrain in a FWD car is very little, and I'd be surprised if it could do the damage you state. I'm not saying you're wrong, as such, but it sounds unlikely in a car of this type to me.

I have never seen a damaged transaxle from the axial loads coming from the side impact that didn't also crack the case.

I have. A few, actually. It's the light knocks that have no perceived damage that are the worst for this, usually. Sliding into a kerb and thinking "ooh, I got away with that" when there is no immediately obvious damage. Also, it was the only other (apart from corrosion and a hidden spring clip) that seemed likely to have caused some sort of mechanical lockage.
posted by Brockles at 7:07 PM on August 18, 2008

Maybe we suffer from the same language. To me the term gearbox and transmission are the same. A transaxle has the differential as an integral part of the transmission. The axle starts after the stub shafts which are attached and part of the transaxle. I assume the real question is have we ever seen these stub shafts stuck in the transaxle?

The OP asked have we ever heard of axles (stub shafts) getting stuck in the transmission? And our (my) experience is yes but rarely. I agree it is likely some hidden fastener holding the axle fast. Rather than some mechanical distortion be it axial (side impact) or torsional (twisted splines).

I would agree that a close look for a hidden circlip would be in order. I assume the axles had been removed and the flanged stub shafts cleaned of their grease to look for said hidden fastener

As I have no experience with the Kia I don't know what are the most economic options. A new transaxle may be the only option verses a rebuild of the differential. One of the issues may be, are the necessary fixtures available to preload the carrier etc.

That would be one weird "light knock" as all half shafts (axles) have some sort of slip joint as the axle needs to vary in length as the wheel travels up and down as a function of the suspension movement. For a curb knock to transmit energy to the transaxle there would need to some damage to a control arm or strut tower. This damage would take up any movement afforded by the slip joint.

Yes Newton's laws are alive and well in the Kia. My point is that low power set ups can break the wheels free and the drive train can suffer severe shock loads as the wheel comes to a sudden stop. Most small power systems aren't engineered to take overloads very well. As an example I never saw torque induced problems with the transaxle on the performance Porsche 911 but saw more than my share of problems with the pedestrian WV Rabbit's transaxle.

To the OP,
I would not drive with clanking CV joints. Your car is of little functional value with failed CV joint. I would try to remove the axle (stub shaft). Who is to do this work is the real question. I would read the shop manual but this really is not practical for most. So I recommend the Kia dealer or at least get a quote from the dealer. If the transaxle is damaged address that issue if and when it happens.

P.S. My experience is that one does not need to remove the part (stub shaft) that goes into the transmission (transaxle) to replace the axles and CV joints. Now please remember I know nothing about the Kia so I may very well be in error.
posted by Mag Plug at 1:30 AM on August 19, 2008

To continue
Sorry I left out in my last post that most hidden circlips are in the wheel hub not in the transmission side of the axle
posted by Mag Plug at 1:36 AM on August 19, 2008

Were the mechanics able to remove the right axle (passenger side)?
posted by Mag Plug at 1:46 AM on August 19, 2008

Thanks for your comments so far. They've been very helpful.

I just got off the phone with the local mechanics, where my car is now. He said they got one last tool ("their last hope" he called it) and if that doesn't work, they're going to have to talk to me about needing a new transmission. I asked him about the CV joint and he said they can't replace it until they get the inner joint out. He also said the casing was fine. I hope I'm using the correct terms.

He called Kia and they told him this is common in these cars, which of course tells me I should've probably taken it to the dealer in the first place.
posted by girlmightlive at 6:21 AM on August 19, 2008