jeep torque converter/flexplate spacing question

98zjstroker

98zjstroker

Well-Known Member
Joined
Oct 14, 2009
Location
concord nc
Ok so I installed my stroker motor the other day and tried to bolt the torque converter to the flexplate. As I turn the crank to line up the bolts the torque converter moves as well due to friction of it being up against the flexplate. After doing some research I found some say that the torque converter must not be seated in all the way.

I know that mine is in fact seated all the way. The first attempt to install the motor it wasn't which is how I know. I could not bolt the motor to the transmission because there was about a half inch gap. After pulling the motor back out I saw that the torque converter was not all the way seated. took it out and checked for damage.

I was very careful and didn't try and force anything. I reinstalled the torque converter and got it to align to all three things (felt the 3rd click) once I got it seated to the pump. It sat inside the bellhousing a good bit instead of flush with it like before. I felt behind the torque converter and there is not much space. any more and the torque converter would be hitting the actual inside of the bellhousing. The torque converter would also not go any further in at that point.

Then I reinstalled the motor. Got the motor and transmission bolted down. I tried to align everything up when I did and I am maybe 1/4-1/2 inch off from the bolt holes being lined up perfectly. Did some more looking and found that a lot of places talk about needing a space gap between the torque converter and flex plate before bolting it in for heat expansion. Its the stock original transmission and torque converter, with a different crankshaft (4.2l). Would that be the cause?

The things I have read that talk about the spacing says that if there is not enough spacing you can wear out the pump and/or damage the thrust bearing during the expansion because it puts more pressure on them. Should I be worried?

I was simply going to loosen up the bolts for the motor and transmission just enough to create a bit of space before rotating the crank the little bit I need to line up everything so I can get the torque converter bolts in. Is this a good idea?
 
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Do you need to flip the flex plate maybe?
 
If you dont have a gap you will ruin the pump in the trans. Something isn't spaced right. Are you sure you have the correct flexplate? Maybe the 4.2 has a different offset.
 
87TPIYJ said:
If you dont have a gap you will ruin the pump in the trans. Something isn't spaced right. Are you sure you have the correct flexplate? Maybe the 4.2 has a different offset.[build.
Click to expand...

Flexplate is the stock one that came in the motor. The only different piece to this equation is the crankshaft out of an 87 jeep 4.2 which is used all the time in these stroker builds. When lining up with the old crank it did not look to have any different offset. Of course this was just eye balling it. Did not measure it because none of the stroker build threads I looked at mentioned this as a problem.

The nose of the crank on the front is longer. But that is a common thing and I order the spacer/adaptor for it. This would not make any difference on the back end only alignment issues for the balancer. I found a video on YouTube where someone replaced a flexplate and ran into this problem.



I think he ran into the problem and 20min and 30sec. But after turning it a few times he said it lined up and he just bolted it on. Now obviously he might run into issues later if this goes cause problems. Wasnt sure if anyone else on here who has done the stroker swap had spacing issues or of there was a gap when the installed.

Also curious as to if it would cause and issue with the thrust bearing or is it just a pump issue?
 
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The flexplate to converter bolt holes on a ZJ are not evenly spaced. 3 of them are at 3,6,9 and one is like at 1230.
With the engine and trans bloted together, flexplate to converter bolts out, can you reach behind the flexplate and spin the converter by hand? If so, it's seated, if not, it's not seated.
 
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Jody Treadway said:
The flexplate to converter bolt holes on a ZJ are not evenly spaced. 3 of them are at 3,6,9 and one is like at 1230.
With the engine and trans bloted together, flexplate to converter bolts out, can you reach behind the flexplate and spin the converter by hand? If so, it's seated, if not, it's not seated.
Click to expand...

Seated into what? The trans pump? When I reach behind the flexplate I can only get a finger or two on the torque converter and it doesn't move. If it did I would be able to rotate it so it is aligned with the bolt holes. After I got the torque converter seated into the pump it would not go in any further at all.
 
I know that the most common issue when dealing with flexplate and torque converter fitment is that the torque converter isn't seated all the way because the trans pump is missed and harder to align then the rest.

I even ran into that the first time putting this motor in when my buddy didnt seat the torque converter all the way into the pump. So we had to pull everything back out. I did it myself the second time and it went in about another inch or so which is about the length of the flat part on the nose of the torque converter that goes into the pump.

I double, and triple checked it the second time just to make sure. Can it be a tolerance issue from factory or something else?
 
If the converter won't spin behind the flexplate, it isn't fully seated.
When you pull the engine or trans back out, put a straight edge across the bell housing. Measure the gap between the converter pilot to the straight edge. Should be approx 3/8" if I remember correctly.
Regardless, if you can't spin the TC behind the flexplate, it isn't seated.
 
Jody Treadway said:
If the converter won't spin behind the flexplate, it isn't fully seated.
When you pull the engine or trans back out, put a straight edge across the bell housing. Measure the gap between the converter pilot to the straight edge. Should be approx 3/8" if I remember correctly.
Regardless, if you can't spin the TC behind the flexplate, it isn't seated.
Click to expand...

It is seated past the bell housing by about 3/8 to 1/2 inch. If it wont go any further can there be another issue? I will pull the motor tomorrow but if it cant go in any more maybe another issue?
 
I know this may be a really stupid question but the crank you used, did it come from a manual trans jeep? Pilot bearing still in the crank?, one would assume it would be obvious but sometimes those are the things we miss when they are right in front of our face....
 
skyhighZJ said:
I know this may be a really stupid question but the crank you used, did it come from a manual trans jeep? Pilot bearing still in the crank?, one would assume it would be obvious but sometimes those are the things we miss when they are right in front of our face....
Click to expand...

not sure if it was a manual but definitely no pilot bearing in the crank. It would not be the first time something obvious got by me
 
Jody Treadway said:
Did you make sure the TC pilot fits in the crank?
Click to expand...
If I say yes,......….but I didn't,...………. but just pretend I did,...……. I assume that won't help. :handed:

Now I wish I would have measured it. I assumed that it would be the same and because it wasn't mentioned in other stroker builds I wouldn't have run into an issue. I guess that is what my ass gets for assuming. If that was the case though wouldn't it prevent the TC from being flush with the flex plate if the pilot did not fit in the crank?

Did you or anyone else see the video I put on here where he ran into the same issue? Is it at all possible for the tolerances to be off and there just not be enough space as there should? Would he end up running into pump failure later on I assume?
 
it was from an automatic. I'd say the TC is not fully seated in the trans if its only 3/8-1/2" from the BH face. Ive had trouble getting them to seat fully, to the point where I had to pull the converter out and move the front pump gerotor slightly to get it to seat.
 
Well I was going to pull the motor yesterday but with all the rain I couldn't. Hopefully Saturday and sunday will be nicer to get this out. Will update with all the measurements and the final results
 
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