I.e. I put the car on jackstands. can I unbolt the trans/ tq conv and access the plate to remove it? Or should I take it to a shop?

Also if the above is possible can I replace the rear main seal myself? I don't have a lift and I don't want to take the trans all the way out.

I have a 2001 ls1 4l60e thanks.

 

Also, what can I expect with a heavier flexplate like the CAT piece? Since it is heavier rotating mass would that translate into less hp less gas mileage? how much more does it weigh vs. the 98-00 flexplate? Reason I ask is I don't drag the car or race it so I don't want a decrease in hp/tq mpg if it isn't necessary vs. getting the stronger 98-00 flexplate?

 

You will have to remove the trans in order to replace the flex plate

 

Removing the transmission is not necessary to remove the flex plate, just follow these steps:

1. Remove engine
2. Remove old flexplate
3. Install new flexplate
4. Reinstall engine.

However, normally the transmission is easier to r&r.

 

The flexplate can be removed without pulling the engine or trans IF you support the back of the transmission with either a jack 0or rear trans mount.

Here's how:
Undo U bolts on the driveshaft U joint at the diff, and remove the driveshaft.
Remove the starter.
Remove the Ring Gear dust shield.
My 67 pickup has an aftermarket trans mount that will slide backward in the frame if the mounting bolts attaching it to the frame are removed so I left mine in but loose. If yours doesn't work the same way, you will have to remove it.
Attach a ring gear clamp using the starter bolts to keep the engine from turning and remove each bolt attaching the torque converter to the flexplate. This takes time as you have to remove the ring gear clamp to bring each one to a position where it can be removed.
My turbo 400 does not have a top bolt attaching the trans to the bklock, only three on each side. Remove the top two. Now, one by one replace the lower two on each side with 3/8-16 grade 8 bolts 4 inches long. Thread them in finger tight until they bottom in the holes in the block. now your trans is supported by the locating dowels on the block ant those 4 bolts. Lever the trans back using a pry bar until it drops off the locating dowels and is only supported in front by those 4 grade 8 bolts. On my truck, I had to move it away from the flexplate 2 inches to get a 12 point socket on the flex plate bolts. I removed the ring gear clamp and jacked the motor until each was accessible at the bottom and then the flexplate just falls out.

Reverse the process on each flexplate bolt to reinstall the new plate but be sure to use Loctite.

Now for the fun part. Just slide the trans forward on those 4 ridiculously long bolts until it contacts the locating dowels. Remove one of the long bolts and replace it with a transmission mounting bolt and use that to move the trans forward onto the locating dowels on each side. It is usually easy if you use one mounting bolt on each side to snug up the trans then Loctite and torque the four you haven't installed and torque to spec. Remove the other two, add Loctite and torque to spec.
Install the torque converter bolts using Loctite and the ring gear clamp and torque each to spec. VOILA' you are almost done. Either re-attach the rear trans mount or install the mounting bolts, reinstall the driveshaft and you are done. My trans never left the truck, the engine stayed in place ant the entire job was done in 5 hours. So, don't let anyone tell you that you have to pull the motor and trans to put a new flexplate in!

 

Ran across this by accident. Thanks for the laugh.

 

Some guys shouldn't be allowed near a car with any sort of tool.

 

Pretty sure it was a joke, and a pretty amusing one

OP, yes the cat piece is heavy. Will you notice? No. Will the car have a funky idle for a few minutes? Yes. Will you need to pull the trans or come damn close? Yes. A hughes 4004x and a TCI are better quality flexplates then the CAT plate IMO....and Ive personally owned several.

 

 

That was actually decent advice; yes it is technically possible to change the flex plate without removing the transmission.
I suppose there are probably some applications where it's easier to remove the engine than the transmission, but the F-Body damn sure isn't one of them.

Also, you responded to a thread old enough to go to elementary school.

The more you know...

 

Back in the day and I mean in the early 80's GM had a quality control problem with flex plates. Mostly on 4x4's. I was a tech at a Chev dealership at the time. It was warranty work to replace it. We hated warranty work because the flat rate was so little compared to out of warranty flat rate work. Except on replacing flex plates. We did all the work on a lift not on jack stands. Get it up in the air, disconnect the drive shaft, rotate and remove the TC bolts, remove trans mount, support the engine, then remove the bell housing bolts and then just wiggle the trans back enough to get at the flex plate bolts. Maybe 2 inches at the most. There was just enough wiggle room in the cooler lines and shifter linkage to move the trans back. Back then we made a special wrench to get at the flex plate bolts.
Warranty flat was 8 hours. We could do it in 4 hours or less. Money in the bank for the techs.

 

Yeah and Generation 1 Small Block Chevy engines had a much more accessible flex-plate; once the torque-converter inspection cover was removed (If the vehicle even had one on).

BTW... we (GM) still had flex-plate cracking issues all the way into the 2000s with the Gen III SBC and the 6.6L Duramax engine.
We actually experimented with some stronger alloys/ more solid plates... but people complained that starting the engine was louder than it used to be.

In the end a softer/ more flexible alloy material with windows punched out of the flex-plate seemed to work out the best for both longevity and noise (and I do not mean grinding noise... just loud rotational droning).

 

I think after 5 years the OP has figured out it easier to just pull the trans.....and as far that post being a smart *** reply.....Joking or not at least he was correct and that doesn't always happen on forums.

 

It might be really, really old, but it is just exactly the advice I needed as there is hardly anyone in our little country down under that really knows what they are talking about when it comes to these real utes!! (trucks or pickups).