flywheel resurface?

[Eagle]

My '87 MJ 4.0L is the same way, and worse in summer than in winter, so heat is part of the problem. About a year before I bought it I saw an MJ that I am certain was this same truck at a garage just a couple of miles from home. I asked the proprietor if it was for sale and he said it was not. It belonged to a customer and was in for clutch work.

I bought it from a young woman, but the title was in her father's name, and his address was the same town as the shop where I saw the MJ a year earlier. I'm guessing it had a clutch job, and they probably machined the flywheel. The issue is as Old_Man described. There is no adjustment in the hydraulic clutch system. It is designed to operate a clutch with everything set within factory tolerances. Shave the flywheel a few thousandths, and the slave cylinder may not have quite enough range of movement to achieve complete disengagement. For the models with the internal slave/bearing unit, shimming the unit away from the back of the bellhousing by the same amount that was shaved off the flywheel should get things back to where they belong.

I'm not sure just what to shim or by how much to accomplish the same thing with the external slave cylinders.

Mind if I butt in...

My flywheel was resurfaced without my knowledge, at least was done without my permission, during the first clutch job some years back. Never imagined that it caused any problems ...

That replacement clutch worked okay, with some occasional chatter, for about 5 years and last summer I changed everything again. Here's the catch:

For some reason, say at start up in the morning, I get about 10-20 real easy shifts before things get stiff. Say after about a half hour of driving, reverse is kind of an issue. After an hour, reverse isn't an option. Normally I stop the engine to shift first.

Since this is a thread about resurfacing flywheels, I will not reply to anyone who asks me anything about bleeding air out of the system.

 

[old_man]

Personally, with all the problem of clutch mastercylinders crapping out on XJ's, replacing the OEM unit with a Howes unit is a good move. They are actually cheaper. They cost around $50 and have a stainless sleeve. You can get a rebuild kit for less than $10.

I requires a very minor amount of fabbing, but you will love it. The larger diameter bore yielded a much more positive clutch feel, much better than stock.

On the flywheels I have had surfaced, they were Blanchard ground. As a side note to let you know I know what I am talking about, I am a tool and die maker.

 

[CODevilDog]

On the same subject, could milling the flywheel cause the fluid to leak or should I be looking some where else? When I got my XJ I was told that the clutch had been replaced and the wheel milled.

 

[Rev Den]

The internal slaves are well known for the ability to self drain fluid. The newer style slave, with the rubber bellows, is a permenant fix. I went thru 6 of the old style before finding that Jeep had redesigned the unit to keep the crap out.

Rev

 

[5-90]

Personally, with all the problem of clutch mastercylinders crapping out on XJ's, replacing the OEM unit with a Howes unit is a good move. They are actually cheaper. They cost around $50 and have a stainless sleeve. You can get a rebuild kit for less than $10.

I requires a very minor amount of fabbing, but you will love it. The larger diameter bore yielded a much more positive clutch feel, much better than stock.

On the flywheels I have had surfaced, they were Blanchard ground. As a side note to let you know I know what I am talking about, I am a tool and die maker.

Oh - I've not doubted you - I can usually tell the difference between someone who knows what he's talking about and who's talking through his hat...

That cylinder - where? Do I get it from Howe, Dewey, Scruemm, and Wenn (my lawyer's firm?) I've usually dealt with Wilwood for performance hydraulics, but that seems to end me up with an awful lot of fab work...

5-90

 

[old_man]

I went to the Howes web site and looked for a local dealer. There was one in Denver and they had it in stock. Most of the performance suppliers carry them, such as Summit.

I took the stock MC and cut off the existing end that hooked to the brake pedal. I filed it down so it would just fit into a coupling nut the size to go on the MC. I brazed it in the end of the coupling nut. All of the pressure is compression so It will hold well. I then added a thin jamb nut. The holes in the cylinder match up with the holes in the firewall great. I grabbed a couple of brass angle adapters to get the ouput around to hook up with the existing line. I actually used a mapp gas torch to braze it since my acetylene bottle was empty.

 

[outlander]

I'd say given the flywheel is of a style which will handle being machined I'd compared it's thickness to a new flywheel of the same type to see if it has been machined before. If it has not I see no problem machining it to clean it up and using it as is.

I think the FSM recommendations are conservative and they want to save themselves from the potential of a flywheel being machined 2..3..4 times to a point where the slave and master will no longer make up the difference.

Taking 0.010" off a flywheel that has never been machined before will only add .010" of stroke to the slave cylinder and approx 1/16" to 3/32" of stroke to the clutch master. Both of these compoents have enough reserve capacity to make up this difference. I can see it being a problem however if the flywheel has been machined numerous times but not if it's only been machined once.

I would like to know the thickness of a new flywheel so I can compare the number to the thickness of the one I had milled....anyone have the measurement?

 

[SteveT]

If the flywheel is machined as 5-90 describes it, and the pressure plate is the same distance from the flywheel as when stock, how does the system need more volume of fluid to function? With an AX-15 and external slave, won't the travel of the piston be the same?

I'm not at all trying to be argumentative, just trying to figure it out in my head. I too had my flywheel turned "accidentally" (sent it to a shop for an opinion, and they turned it without my asking them to).

That was a year ago, and no problems, yet.

Steve

 

[outlander]

So I was doing a little shopping for a new flywheel today.I don't want to take my chances with the one I had resurfaced(wish napa would have warned me)
anyway,this is what I found:http://www.partsamerica.com/ProductList.aspx?PartType=267&PTSet=A&SearchFor=Flywheel / Flexplate
The standard brand down at the bottom is a good price,but are they re manufactured?It calls for a core so I assume they are re manufacturing these flywheels?If they are wouldn't someone be in the "same boat"so to speak?I mean would these flywheels be out of tolerance if they were turned in the re manufacturing process?

 

[Eagle]

PartsAmerica wants me to log in, it won't go right to your link. But ...

The URL you posted ends in "flexplate" -- the flexplate is what's used with automatic transmissions. It's not the same as a manual transmission flywheel.

 

[outlander]

I know it has a listing for a flexplate,but this is a flywheel I'm talking about,that's listed also.

 

[outlander]

try this
http://www.partsamerica.com/ProductDetail.aspx?mfrcode=SFW&mfrpartnumber=1004&parttype=267&ptset=A