How-to Fix Flexplate Knocking

Old 02-22-2012, 11:55 AM
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This How-To thread was made possible by "cruiser54" and "BotakBeng." Thank you guys for all your help and patience.

If you have an automatic transmission and you have a similar knocking/ticking noise, it is possible that your flexplate to torque converter bolts might be loose.

Here is a video of the sound my XJ was making. You can tell it is coming from near the tranny, not from the motor:

Flexplate to Torque Converter Knocking - YouTube

First, I gathered the basic stuff i would need for this. 18mm socket, 18mm box-end wrench, 13mm socket, 13mm box-end wrench, 15mm box-end wrench, brake parts cleaner, and some red loc-tite. (Not everything is pictured here):

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Next, I grabbed the 18mm and 13mm sockets and wrenchs, climbed under the jeep, and removed the flexplate inspection cover, pictured here:

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Here is the inpection cover after I removed it. you can see that it is filthy, covered in oily gunck, and i had to bend it a bit to get the thing off:

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Then I cleaned the cover and mounting bolts, using brake parts cleaner, a toothbrush, a rag, and some elbow grease (you can see it is still bent so I could put it back the way it came out):

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Now I could finally begin the work on the flexplate to torque converter bolts. For this I used a 15mm box-end wrench, brake parts cleaner, and red loc-tite.

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I lucked out and the first bolt came out quite easy. Probably the main problem. I cleaned it with brake parts cleaner, added some loc-tite (yeah I know the stuff I have isn't really loc-tite, but works the same), then put it back. Getting that bolt back in was a huge PITA, due to the oil pan restricting the work space. It was also very hard to get it fully tightened again because the flexplate wanted to keep moving. You can wedge a flat-head screwdriver into the flexplate teeth to keep it from moving. Anyways, here is the flexplate to torque converter bolt:

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After that bolt was reinstalled, I repeated this process to the remaining 3 bolts.

If you are fortunate enough to have an open ended torque wrench, or one that is small enough to fit up there, the torque specs are:
Flexplate to Torque converter bolts -- 28ft/lbs
Inpection Cover Bolts -- 181 in/lbs (these are according to "CCKen", and I have not verified this)

After that, I fired up the jeep (without the flexplate inspection cover on, just in case I needed to tighten the problem bolt some more). Problem soved!

You can watch this video after I did this and compare it to the first video on this thread. HUGE difference (now you can clearly hear my exhaust leak that is before the catalytic converter, lol, which my friend will be fixing with a weld next week lol):

Flexplate to torque converter bolts tightened. Problem Solved! - YouTube

I then put the clean inspection cover and clean bolts back into place, of course having turned the engine off again lol. (I know that cleaning these parts wasn't completely necessary, but I like things to be clean lol):

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Last edited by XJ Stryker; 05-08-2012 at 11:08 AM.
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Old 02-23-2012, 11:57 AM
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Originally Posted by BurninBridges View Post
Now I could finally begin the work on the flexplate to torque converter bolts. For this I used a 15mm box-end wrench, brake parts cleaner, and red loc-tite.

Another important point I forgot to add when doint this write-up! Thuroughly check the flexplate for cracks!!!

You may have a sound similiar to the one I had that can't be fixed by simply tightening the bolts.

Check for cracks near the bolts.

Check the bolt holes for wear and make sure they are not ovaled out.

Also check for circular cracks radiating outward from the center of the flexplate as well.

If you find any of these while inspecting your flexplate, it is cause for rejection of the flexplate. Replacing the flexplate is quite a bit more involved. It requires access to a transmission jack and you will have to drop the tranny.

Here are some links that my help you replace the flexplate:

Flexplate Remove, and replace, closeups - NAXJA Forums

Flexplate Problems (Nice Pics of Crack)- CherokeeForum

changing flex plate (Nice Step-by-step from JeepingDan) - CherokeeForum


Hope this helps!!!
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Old 05-08-2012, 11:12 AM
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Cleaned and Locked!

If there is something I deleted that you want to reinclude PM me and we can try and get it on here.
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