Why did Dodge decide to taper cut the flywheel

[TWebster]

Hey Guys,

I need some help here. In the not to distant future, I will be replacing an end of life clutch. I already know I'm going with a SB dual disc due to camper and towing needs.

My question is, is there a functional purpose for the taper cut on the flywheel, or is it just to help the driver engage it without chatter? I did a SB single on my 5.7 gas truck w/ a g56, had them straight cut the flywheel, and its like any other clutch, it engages and pulls without any problem-----it BTW, is getting near it end of life also, well over 100K on it. The only reason the original was replaced was because the pilot brg died and ate the end of the input shaft. Truck has 238K on it.

The truck I question about is 2005 1ton dually 5.9, 4wd, nv5600, 4.10 diffs.

Thanks for all your replies

 

[RVTRKN]

sorry duplicate post

 

[RVTRKN]

I believe its to help in centering the pressure plate and clutch disk, but its a guess at best. I'm surprised you are aware of it, most don't know and have the flywheel resurfaced flat. But I don't really know why, I'm sure if you contact South Bend Clutch, any of the associates that answer the phone can answer that for you. Your 5.7 should have a 5spd NV4500 transmission, I haven't owned one so I'm not sure if its tapered as well. Just know the NV5600 flywheel has a tapper to it. My transmission tech alerted me of the tapper right after I bought my 04.5. If it were me, I would go with a new OEM flywheel and clutch OR order a new SBC flywheel and clutch packaged deal.

 

[GCroyle]

Concave Flywheel taper does exist and it has a purpose, let the confusion continue.

I have read this in the Dodge FSM describing the existence of the special grind taper. Problem is that the FSM covered the gas and diesel engines as one description. We have measured the concave on gas engine FW's a few thousands outer to inner edge. Valeo (a major supplier of clutches, facings and DMF's. The DMF's were on the famous 7.3L up to '97) published a bulletin describing the matching taper on pressure plate castings.

The casting surfaces could be considered as FLAT, CONCAVE or CONVEX.

Convex, center edge higher than OD, big problem. This clutch will slip.

Flat. This is the way most stuff turns out.

Concave. The facing ID is lower than the facing OD area by a couple thous.

Why concave? The Valeo bulletin states they did this to start the clutch engagement on the OD of the facings where you have the highest mean radius. Mean radius, think of putting the pull on a breaker bar as far out on the bar as possible. Same pull results in higher torque applied to the bolt. And they add that as the castings heat up they wind up flatter but not going convex. Convex is a slip producing condition. Still have a copy of this bulletin at work.

We have seen the concave on Gas engine FW's from Dodge but not on the Cummins supplied solid flywheels.

Argue as you wish. I know what I've seen and measured on NEW flywheels.

 

[Joseph Donnelly]

I have used and machined flywheels for Cummins Rams since 1996. Always ground flat (not lathe turned), always worked fine.

 

[TWebster]

RVTRKN,

It is in fACT A G56 6 SP. The biggest difference is the input shaft in that the pilot is smaller than the unit for the 5.9. The 5.7 did have a taper cut, but I had it resurfaces flat

 

[TWebster]

Thanks guys,

I believe I'll be having it "GROUND" flat, From a physical stress point of view, maybe having the taper spreads the stress on the disc itself more evenly, but, I believe I may be reaching on this one.

 

[RVTRKN]

That's one of the benefits of converting to a SMF from SBC, they upgraded the pilot bearing.

Flat is a users choice, and is a preference I would not subscribe to. If SBC confirms their FW is machined flat then it will be resurfaced flat, if it has a tapper, then I'll get a shop they recommend in my area to resurface it. It won't be the first flywheel I've had resurfaced, and have never had a problem, but the NV5600 is the first I've heard about in tapering the FW.

 

[jhenderson]

I'd be very surprised if you found a local shop to resurface a flywheel with a taper. That would require a CNC surface grinder. I've never seen one in a local auto machine shop. I've resurfaced several flywheels for our trucks and had no trouble with them being ground flat.

 

[RVTRKN]

Like I said, I would go with whoever SBC recommended to do the resurfacing, if they are also tapered. When I convert my G56 to a NV5600, it'll be with an SBC flywheel and clutch so they should be matched perfectly.

 

[AH64ID]

Hey Guys,

I already know I'm going with a SB dual disc due to camper and towing needs.

It sounds like you're still on the OEM clutch, and if it's holding the power you are making I am not sure you need to go to a dual disc clutch. SBC has several single disc clutches that work very well for towing/hauling. The OHD will be my next clutch. It engages VERY smooth and holds the 375 rwhp my dads 06 has without issue. It drives a lot better than the OFE I have now, which also doesn't have any issues hold/engaging while towing/hauling above 20K GCW with over 400 rwhp.

Many salesmen go to the dual disc's right off the bat, but single discs are still available and hold plenty of power. They are also much quieter, and cheaper.

 

[RVTRKN]

I vote for quieter, cheaper is good, but I'm tired of the noise, especially below 1500 rpm, but mine is a G56.

 

[AH64ID]

The NV5600's I've heard with a DD are not much, if any, quieter than a G56.

 

[RVTRKN]

My NV5600 was not much effected by the NVH the Cummins produces with a SMF, unlike my G56 with a SMF.

 

[TWebster]

It sounds like you're still on the OEM clutch, and if it's holding the power you are making I am not sure you need to go to a dual disc clutch. SBC has several single disc clutches that work very well for towing/hauling. The OHD will be my next clutch. It engages VERY smooth and holds the 375 rwhp my dads 06 has without issue. It drives a lot better than the OFE I have now, which also doesn't have any issues hold/engaging while towing/hauling above 20K GCW with over 400 rwhp.

Many salesmen go to the dual disc's right off the bat, but single discs are still available and hold plenty of power. They are also much quieter, and cheaper.

Thanks John,

I am currently on the original clutch, but I'm now hauling a 5K +/- camper, and intend to trailer haul a rubicon in the not to distant future. This is my reasoning for this

 

[AH64ID]

Thanks John,

I am currently on the original clutch, but I'm now hauling a 5K +/- camper, and intend to trailer haul a rubicon in the not to distant future. This is my reasoning for this

Neither of those warrant a dual disc clutch. Clutches are rated on power, not weight. You can get a dual disc if you want, but you have no apparent requirement for one.

 

[jeepit]

TWebster...looks like we haul the same loads. Where are you wheelin?

 

[TWebster]

TWebster...looks like we haul the same loads. Where are you wheelin?

Jeepit,
I currently do not have a jeep, as there is nearly nowhere in the area to wheel around here-----mostly farm fields and towns and cities, but----in the not too distant future, we're planning to move to AZ for retirement------then the fun begins, until then, I'm getting everything else ready. We had a 95 wrangler some years ago and really enjoyed it, but the family got bigger, and the vehicle needed to also.