258/tf727 flex plate question

Webbinator

Webbinator

Well-Known Member
Joined
Mar 20, 2005
Location
York, SC
258/tf727 flex plate question-UPDATE

Beginning a swap out of my T176 to a tf727 in my '78 CJ7 with a 258. The 727 came out of an '80 J10 also with a 258. I got all the necessary pieces with it. The ring gear on the flexplate that came out of the J10 was a little ate up so I went to Advance Auto and ordered another one for an '80 J10 with a 258. The new one that came in matches the old one identically except that it has a counter balance weight on it whereas the old one does not. Is this going to cause a problem if I use it or should I return it and try to get one without the counter balance? Thanks.
I seem to have found the correct flex plate now. Only weird thing is that it is listed in all the books to be used with a 904 or 999 trans. It matches the bad one that came with the tranny perfectly and there is no counter weight. Now I get to pull the tranny back out and change it. :bounce2:
 
Can you get just the ring gear for the flex plate?
 
If I'm not mistaken, it's welded onto the flex plate in several locations. I think you can change the ring gear on a flywheel for a manual, but you have to replace the entire flex plate. The new one was only $50 bucks, but I want to make sure this one will work with the counter weight on it.
 
Webb,
Did you get a Motormite 04302? If not, I bet you got the wrong one...dang I wish I had my catalogs in front of me. Did you go to the Advance in York?
 
bowtieman55 said:
Webb,
Did you get a Motormite 04302? If not, I bet you got the wrong one...dang I wish I had my catalogs in front of me. Did you go to the Advance in York?
Click to expand...
Nope, I got the other one they had listed for supposedly the same application. At the time I ordered it, I didn't realize they had two of them available. I actually took it back to Advance and started asking questions. The counter guy explained to me that they have to be balanced to spin evenly so that you don't get vibrations. He said that is the only reason it has the weight welded on like it has. And yes, it was the Advance Auto in York. He also pulled up the other one to look at it. He showed me what looked like weld marks on one side and said that is where the weight is located on the reverse side.
 
Just checked out Advances web site and did a search for the flex plate I'm looking for. Strange thing is that they list the same two part numbers for the 6 cyl flex plate AND the 8 cyl. one.
??????????
 
I would have to agree with the balancing procedure...reasoning for the counterweight. Sounds like you may have talked to Jamie...if so, you should be good to go
 
It was actually the older heavy set guy with the head full of graying hair. Not sure what his name is. He seemed to be pretty confident on what he was explaining to me about the balance weight.
 
258/tf727 flex plate question- UPDATE

OK, finally got the trans swap to a point where I could at least start the engine again. I went ahead and used the only type of flex plate that I could find. This was after trying several different parts stores. They all had pretty much the same thing and it was the one WITH the counter weight. Now with the engine running, there is definately some sort of vibration happening that wasn't there previously with the manual trans. It is more pronounced at lower RPM's and lessons as the throttle is increased, but never really goes away. Could this be from the flex plate with the counter weight?
 
yes and dont run it.
That vibration is being transmitted directly to your crank and input shaft/pump...neither are good to shake around.

Richard at Advance thinks he know a lot.
You can change the ring gear on the flex, but you will pay more than for a new one.

You need to get the plate for your engine. The key is for the harmonic balancer and the plate/flywheel to match (externally/internally balanced) the tranny just bolts to it.
 
SkyHiK5 said:
yes and dont run it.
That vibration is being transmitted directly to your crank and input shaft/pump...neither are good to shake around.

Richard at Advance thinks he know a lot.
You can change the ring gear on the flex, but you will pay more than for a new one.

You need to get the plate for your engine. The key is for the harmonic balancer and the plate/flywheel to match (externally/internally balanced) the tranny just bolts to it.
Click to expand...
SkyHi is kerrekt. I ran into this topic while reasearching for a 727 swap onto a 258.
 
SkyHiK5 said:
You need to get the plate for your engine. The key is for the harmonic balancer and the plate/flywheel to match (externally/internally balanced) the tranny just bolts to it.
Click to expand...

If you know where I can find one without the counter balance, please let me know. I tried Advance, Auto zone, and Napa. They all had the counter balance. I'm asking for one for a Jeep 258.
 
I would try to gete on e for a 78 CJ not an 81 J10, see if its different.

Here is next thing I would check.
The closest year that offered a I6 with both a standard and an ATS from the factory.

Next see if they list the same harmonic balancer. If not, you may have to change that as well... or *just grind the spot welds holding the counter weight.

* Im not 100% sure that woul work but I cant see why it wouldnt
 
Here are a couple of pics of the original flex plate that came with the tranny and one of the entire reason I felt like I needed to replace it. Notice there is no balance weight.
DSC_0657.JPG
DSC_0658.JPG
DSC_0660.JPG
 
BTW, if you need a hand holla.....
My crap is so far down...itd be fun to help someone actually get something running.
 
Back
Top