What are these???

[Jeepster4wd]

thing to left is flexplate?? and thing to right is flywheel correct??

 

[ChiXJeff]

No. The item that is circled on the left is a cover plate. The item on the right is the flexplate.

For some reason I don't know, it's called a flexplate with an auto trans, and a flywheel with a manual. Yes, they are apparently different.

 

[Jeepster4wd]

ooh ok. thanks

 

[5-90]

Correct. The flexplate is used with the automatic transmission to offer an interface between the crankshaft hub and the TC. There is very little mass involved, the rotating mass is provided by the TC and the gallon of fluid in it (ever pick up a full TC?)

A flywheel is used with a clutch, is about an inch thick, and offers the other side of the "sandwich" formed by the clutch assembly. It is also an important element of the rotating mass at the rear of the engine (along with the clutch cover - but the whole assembly still masses less than a torque converter.)

Either way, the teeth for the starter gear are found on both of them, and (for those of us with 4.0) the "tone ring" is on them as well - that's the little "cage" part around the circumference of the wheel.

The inspection cover should be a two-part plate, there is a part that goes between the engine and transmission, and a lower part that should be removable independently for inspection of the bolts and such. You would also be able to spin the flywheel/flexplate by hand from there, for inspecting the gear teeth and making sure the bolts are tightened properly.

5-90

 

[gupandme]

kinda off-topic, but what does the tone ring actually do? anyone know?

 

[5-90]

On the later XJ's (ChryCo, not Renix) the CPS is a "Hall effect" switch, actuated by the tone ring. Similar switches are used in Chevvy and Ford distributors, and work quite well. The nice thing is that a Hall effect will work even when dirty or wet, and do not require contact between the parts. Also, a Hall effect will work from only one side, instead of needing to be on both sides (like the optical interruptor used in the Mallory "Unilite" distributors")

The Renix version works by generating voltage (caused by the passage of metal past a magnetised sensor) and the ECM reads the pulses to determine the location of the crankshaft.

Either way, the end result is the same - a signal is generated that tells the ECM where the crankshaft is, a signal is generated by a similar sensor in the distributor to tell the ECM where the camshaft is, and both signals are used to generate pulses for ignition and fuel timing.

5-90

 

[Jeepster4wd]

yea the TC was very heavy. it also spilled aton of AT fluid all over my garage when we pulled the motor. anyone know of a good place to get a replacement flexplate? and how much do they run? damn bolts came loose and started banging against cover. so the holes got rounded out pretty good.

 

[ChiXJeff]

You may be able to get a replacement flexplate at the local parts store.

The only place I found for flywheels (for stick shifts) was the dealer. Cost was $125 or so 3 years ago.

 

[5-90]

Yeah - when I needed one I got it from Pioneer/Barnes thru my local - I think it was $40-50. I also got ARP bolts (the set I got was for a Pontiac with an auto - but I'm cranky and I like good hardware,) but they were spendy (and WORTH it!) The threads on the flexplate bolts are 1/2"-20, and they're right about 5/8" long, IIRC. That gives you enough to find them in the ARP catalogue.

MAKE SURE to use LocTite when you put it all together, or you will have it happen again. I usually use LocTite 242 for that, it works well (medium strength.)

5-90

 

[gupandme]

Either way, the end result is the same - a signal is generated that tells the ECM where the crankshaft is, a signal is generated by a similar sensor in the distributor to tell the ECM where the camshaft is, and both signals are used to generate pulses for ignition and fuel timing.

5-90

I figured it must be something like that.Thanks.

 

[EMTJeepers]

good tool choice

thing to left is flexplate?? and thing to right is flywheel correct??

I like the duct tape myself arty: