missingone

put a rebuild in y 1996 xj, the flex plate had some bends in the ring. So I purchased a new one from O'Reiley's. Pioneer, about $140. I put it in, no problems, hooked everything back up and went to start it. The noise that came from my engine was the worst thing I could've imagined. I haven't heard that before on anything, and so I started to run down what I could've dine wrong. I changed the starter, Nope, checked the bolts plate and torque, nope. A friend tells me that where I bought it is why. I guess the aftermarket line will have fewer teeth. In turn the starter gear isn't meshing up with the plates teeth causing it to sound like it trying to rip the pistons out through the rear bearing. My question is this; has anyone heard of this, the noise and the amount of teeth being reduced in the aftermarket? somebody, please, point me in the right direction in this matter, I really need this to run, I need to go back to work.

Dave51

Yep. Occurs enough such that if you want

get OEM.

Dave51

BTW what's the Part# of the plate you got from O'Reilly's?

The parts manual calls for 5211 8551 but an Amazon vendor says that won't fit.

Another vendor says 5211 7761 is the correct part.

Keyxj

The flex plate I ordered from O’Riellys is a Pioneer FRA530.
The one that came from Rock Auto and looks like is a problem, was an ATP Z337.

I will confirm ring gear tooth count on original and both aftermarket flex plates this morning.

Keyxj

Well, I have a whole update to post, but that will have to wait until I am recovered from today.
Bottom line is I measured the flex plates, and found the ATP unit is the problem, as it’s oversize.
The Pioneer unit was also a touch oversize, but nowhere near as bad.
Put the Pioneer unit in, and got it all back together today.
Started it and no noise.
Haven’t driven it yet.

cruiser54

Damn aftermarket crap anymore!!

Keyxj

Here was my day yesterday.
Got the Email from O’Reillys that the Pioneer Flex plate arrived.



Opened the box in the car, and was kinda upset to find this one has a bell shaped flange too!


Here they are…
Original on left, ATP in the middle, Pioneer on the right.



I can confirm, all 3 have 164 teeth on the ring gear.




So, I sat down with some digital calipers and measured:
1/ The overall thickness of the plate from ring gear side to the top of the crank position sensor ring.
2/ The height of the crank position sensor ring.

Like this:





Here was my results in MM, as it’s easier for me(I’m a Brit) to see the differences.



You can see from this the ATP plate is 2-3mm thicker/deeper, from the crank mounting flange,

Also, I measured the overall diameter of the Crank ring and found the ATP to be bigger too.

Oringinal


ATP


Pioneer.


A combo of these discrepancies, meant the ATP touches the passenger side of my transmission bellhousing just above the starter.





I could just about replicate it.
Put the Pioneer flex plate on, and it’s not touching now.
Started it last night and it sounded fine.
Tired and aching today… at 62 years old, I got the trans out one afternoon, and back in the next afternoon, as well as replacing the Engine mounts.
No Gym membership needed!

kmessinger

Lots of fun with flexplates lately, at least i'm not alone. I measured the OEM 5211 8551 plate that I took off in the interest of providing more data to anyone that it might help.

PN: 5211 8551 OEM (measurements are +/- 0.8 mm or 1/32", I used a tape measure with 1/16" increments.)
Overall thickness: 37.3 mm
Flange Depth: 27.0 mm
Inner ring diameter: 13"
Teeth Count: 164

didn't explicitly count the # of teeth on the replacement ATP but I'm fairly confident they are the same #. I laid them on top of each other and they lined up, and the teeth also engaged without binding as i rotated the two when I mated the teeth together.

I'll measure the ATP Z337 IF I have to take it back off, still crossing my fingers that the CPS is causing my rough running issue since I don't notice any grinding when turning everything over by hand. waiting on a new sensor in the mail.

Kudos on getting that in and out that fast! i'm 28 yo and that sounds miserable to me..haha.

exasemech

If you look at post#7 it's interesting how many balance holes had to be drilled in the two C.R.A.P. plates vs the OEM one.
what garbage

Lifted_BlueXJ

I’ve tried the atp and pioneer and both still make a grinding noise when I start it!!!!

goodoleboy

A friend had a similar problem with a flexplate he bought on the internet. Look at the depth of the inset / offset / recess on the flat portion of the new vs old plate. The difference caused his starter ring and CPS ring to be positioned either farther forward or back ( I can't remember) and rubbed scraped on the bell-housing portion of the auto transmission. He reused the original and it ran fine.


Good Luck

goodyoleboy