jimoshel Posted July 13, 2013 Share Posted July 13, 2013 Posted Yesterday, 10:45 PM Quote// Also, do not have a 4.0 flywheel resurfaced, as the surface is not supposed to be flat, but has a slight cone shape to it. Resurfacing it on a lathe will remove that cone shape, instead making it perfectly flat.//quote Not meaning to hijack thread but I am curious. Why can't you machine the surface flat and use it? As far as i know, except for some early Fords, all fly wheels are flat and seem to work OK. Do they use a special disc and pressure plate? Can't a disc from another year be used? How deep is the cone? .001 inch? 3/8"? 1/2" ? Curious minds want to know. :dunno: Some peopletry to turn back their odometers.Not me!I want people to know 'why'I look this way.I've traveled a long wayand some of the roads weren't paved.. Quote MultiQuote Edit Report Link to comment Share on other sites More sharing options...
jimoshel Posted July 13, 2013 Author Share Posted July 13, 2013 Posted Today, 11:01 AM Just checked Auto Zone part numbers for a '88 4.0, '91 4.0 and a 96 4.0. They list the exact same part number for just clutch disk and the clutch set. Disk and pressure plate. Same specs, clutch OD=10.4. ID=1 1/8. spline count=10. For all 3 years. So now can somebody explain why retaining the cone is so important? Link to comment Share on other sites More sharing options...
Eagle Posted July 13, 2013 Share Posted July 13, 2013 So now can somebody explain why retaining the cone is so important? First, because the factory service manual specifically says NOT to resurface the flywheel. (Which doesn't really answer your question of "Why?"). Second, because every single person I know of who has had a 4.0L flywheel resurfaced has reported problems with the new clutch, and in most of those cases replacing the flywheel cured the problems. Link to comment Share on other sites More sharing options...
AZRick Posted July 13, 2013 Share Posted July 13, 2013 So now can somebody explain why retaining the cone is so important? First, because the factory service manual specifically says NOT to resurface the flywheel. (Which doesn't really answer your question of "Why?"). Second, because every single person I know of who has had a 4.0L flywheel resurfaced has reported problems with the new clutch, and in most of those cases replacing the flywheel cured the problems. Add me to that list Link to comment Share on other sites More sharing options...
HOrnbrod Posted July 13, 2013 Share Posted July 13, 2013 Just quickly searching I found a couple of reasons as to "why" the FSM recommends not resurfacing the flywheel: 1. The flywheel isn't convex but it has a recessed center and if you cut the flywheel too much the flywheel bolts could hit the damper springs. It may not happen right away but as the disc wears the damper springs get closer and closer to the flywheel bolts and won't allow the clutch to disengage. and.......2. The crown is there to reduce clutch grab and shock loading and it makes for a more gradual clutch engagement. However opinion seems to be divided about 50-50 about ill effects caused by resurfacing the flywheel. Me - I'd replace it, not resurface it. Link to comment Share on other sites More sharing options...
jimoshel Posted July 13, 2013 Author Share Posted July 13, 2013 Replace it with a later year? '87-'89 are getting scarce. My mind is just to logical to accept 'because'. If something is doing something, there's reason for it. Link to comment Share on other sites More sharing options...
HOrnbrod Posted July 13, 2013 Share Posted July 13, 2013 Crown makes them - a bit over $100 shipped. If I'm changing a flywheel and clutch disk or more and there a 50% chance (or whatever it is) I may have problems if I resurface, I'll replace it for a few extra $$ rather than deal with the aggravation. Same with everything else. Aggravation makes me aggravated. Link to comment Share on other sites More sharing options...
Dadinator Posted July 13, 2013 Share Posted July 13, 2013 Was warned about this "after I did it" Been over a year and no ill effects on resurfaced flywheel yet. Though the transfer case is crap right now. Link to comment Share on other sites More sharing options...
1987Comanche Posted July 13, 2013 Share Posted July 13, 2013 I've had 2 flywheels resurfaced: Maura (4.0 Renix) & Georgia (4.0 HO). Both worked ok after machining with a new clutch. Link to comment Share on other sites More sharing options...
onlyinajeep726 Posted July 14, 2013 Share Posted July 14, 2013 How do you tell if the flywheel has been resurfaced? I just bought a used flywheel from a '89 4.0/5 speed and it doesn't look as though anything has been done to it... Is the "cone" very noticable? Anyone have a before and after shots? Here's what mine looks like: Link to comment Share on other sites More sharing options...
Eagle Posted July 14, 2013 Share Posted July 14, 2013 The profile is not at all noticeable. Link to comment Share on other sites More sharing options...
Geonovast Posted July 14, 2013 Share Posted July 14, 2013 Replace it with a later year? '87-'89 are getting scarce. My mind is just to logical to accept 'because'. If something is doing something, there's reason for it. Remember the CPS windows. You cannot put a 91+ flywheel into a Renix truck. It will not run. A Renix 4.0 must have an 87-90 flywheel. Link to comment Share on other sites More sharing options...
cruiser54 Posted July 15, 2013 Share Posted July 15, 2013 Replace it with a later year? '87-'89 are getting scarce. My mind is just to logical to accept 'because'. If something is doing something, there's reason for it. Remember the CPS windows. You cannot put a 91+ flywheel into a Renix truck. It will not run. A Renix 4.0 must have an 87-90 flywheel. Beat me to it. absolutely correct. Link to comment Share on other sites More sharing options...
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