Saturn transmission input shaft nut

In my last post, I went through the process of changing the valve body of the automatic transmission in the Saturn SL1.

In this post, I’m going to cover how you replace the input shaft nut in the automatic transmission. The input shaft nut becomes loose sometimes, when the reverse slam is present. The slamming of the transmission (due to a faulty valve body) will cause the nut to loose it’s torque, and spin off the shaft. This can cause slamming in the forward gears, and can lead to costly repairs – you’ll eventually replace the whole transmission if you ignore it.

This is a little more involved than replacing the valve body. Expect to spend 2-3 hours on this fix.

So, …here we go again:


1. Jack up the car, and remove the wheel. Drop the suspension by un-bolting the 3 bolts on the strut tower, and the two big bolts at the hub assembly. Then remove the plastic wheel well guard. You’ll see the side of the transmission now.

Jack up the car Remove the suspension, do not worry about alignment problems Remove the side wheel well guard


2. Next, unscrew but do not completely take out the two bolts that hold the engine cradle to the body. There is one at the front of the car, and one just under the driver’s side. Drop the cradle about 1.5 inches. You will now see that the transmission cover clears the chassis. This is important, because when we pull the cover, there are two shafts attached to it – THOSE SHAFTS CAN NOT BE BENT!!! You’ll see as we go…

Drop the engine cradle, but do not completely remove bolts You will see that the top of the cover now clears the chassis


3. Get out a piece of cardboard, and make up a template for the bolts. Some of them are different lengths, so you need to know what hole they came from. Unscrew the bolts, and CAREFULLY pull out the cover, you will see the shafts I was talking about in step #2. DO NOT BENT THEM!!!

Make up a bolt template from some cardboard The two shafts connected to the cover. DO NOT BEND!! The two shafts connected to the cover. DO NOT BEND!!


4. Here is the input shaft nut. See if it is loose. If it is, replace it with an OEM nut from your local Saturn dealership, and tighten it to 126 ft.lbs. You will need a 23mm THIN-WALLED 12-point socket. The keyword is THIN-WALLED. The regular thick walled sockets will not fit over the nut.

Exposed clutch packs The input shaft nut


That was the easy part. Now you have to put the cover back on, and align the shafts with the holes. Sounds easy? It isn’t. Took me 15 minutes to get them back in. The important thing is to remain calm, and patient. DO NOT jam them back in, or hammer it back on. You’ll risk damage to the internal seals in the transmission and THEY ARE NOT serviceable and/or fixable. So take your time.

Putting everything back together is the reverse of taking it apart. :)