The dealer said they were told not to replace any flywheels till the new flywheel design came out. I thought the new flywheel was released in August and was part #24232434 with a national backorder. Am I missing something here? Does anyone have a bulletin number or something for him to reference? They seemed fairly well informed of the situation with our trucks but I thought I could get on a backorder list or something.

I had my flywheel replaced on 11-12-04 with the part number you list (24232434). It is my understanding that this is the newest version.

Crawler Hauler,

Jon S is right. The dealers should be able to get the new flywheel now without any wait time. I had one of the first ones done back in August. I'm thinking that your dealer doesn't know up from down.
Jim

Just spoke to the dealer and they did find the correct parts and should be fixed as soon as the parts are in. It stinks being the only manual trans truck most of the dealers around here have sold, they have to go through a huge learning curve every time I take it in.

Question for the experts...

...Did GM put a different flywheel in the C4/C5 D/ZF trucks, than in the LT's??

I've not had any problems as described in any of these "Flywheel" post problems so I'm wondering if I'm just real lucky or they use a different part (my GVWR is 19.5K with 4.44 Rear, if that makes a difference).

Just wondering.

Question for the experts...

...Did GM put a different flywheel in the C4/C5 D/ZF trucks, than in the LT's??

I've not had any problems as described in any of these "Flywheel" post problems so I'm wondering if I'm just real lucky or they use a different part (my GVWR is 19.5K with 4.44 Rear, if that makes a difference).

Just wondering.
The 4500/5500 trucks have a larger, solid/single mass flywheel. CPMac's is the only solid/single mass flywheel setup for the 2500/3500 series trucks that I am aware of.

The 4500/5500 trucks have a larger, solid/single mass flywheel. CPMac's is the only solid/single mass flywheel setup for the 2500/3500 series trucks that I am aware of.
Why can't this be used is a 2500/3500 truck since it's the same trans as long as you don't need max performance?

Michigana Joe2

Thanks for your valuable response. I was beginning to wonder why, in over 120K Miles, I have not had any of the LT problems.

It is also very apparent, now that I think of it, that there is quite a bit of difference between the two, since the C4/C5 B/H is much larger than on the LTs, but I wrote it off as being due to the space available within the LT drive train tunnel.

Jeli, the space issue may be the answer, there just is not enough space under the cab to accomodate the MDT setup. The MDT cab is above the frame, while the drive train is between the rails, therefore MDT's have a flat floor from the engine access hatch to the rear of the cab. Note that the MDT's are configured with the cab forward, about 1/2 way over the engine (hence the access panel).

I thought the same exact tranny was used. I didn't realize the other has a larger bell housing. It makes sense because you need a higher inertia single mass and the easiest way is in a larger diameter versus thicker.

The 4500/5500 flywheel is only a 1/2" or 1" bigger (I forget which). I was thinking of trying to convert to one before CPMac came out with his setup. I was told by an engineer at GM that there was more to it than switching bell housings. I was told that there are differences in the engine block and that water jacket passages would make any such conversion nearly impossible. Fortunately, CPMac came out with his setup before I tried anything crazy...

MJ2,

Dug out my Build Sheet and this is what it says: "TRANSMISSION ML6 6-SPEED S6-650 ZF Manual Transmission W/OD - inc: deep low, 6 bolt SAE LH provision, pwer take off, 13" Valeo Clutch (N/A w/UXT Trans Temp Guage) *CREDIT* -$1,210.00".

So that's a 13" clutch, which I thought was the same as in the 2500HD/3500 LTs. Maybe I've misread something somewhere on the GM site.

I was thinking about this and I find it hard to believe GM and ZF would make a special main trans housing let alone a different engine block for C45 and 55 trucks. Nothing I found matched completely. A 2003 C series brochure shows an LB7 engine and M50 6 spd. My '03 has an LB7 and ML6 just like Radio's C5500. I could never track down what an M50 6 spd is but looking at the GM Fleet website I found the RPO codes for 03 to 05 trucks. On that site 5500's do not get LB7's but other Dmax engine codes. Obviously a different code for the 230? hp engine. In 05 the codes changed, I'm assuming due to pickup's LLY engine.

I'm not 100% convinced the flywheel / clutch is different. Unfortunatley when I was checking into tracing the part numbers for the 45/5500 factory engine brake I needed a VIN number to work from. Maybe Radio can call his dealer and have them look it up?

I found the M50 code. It's the light duty New Venture 5 speed. That means the 03 brochure I found was total bunk!!!

I was thinking about this and I find it hard to believe GM and ZF would make a special main trans housing let alone a different engine block for C45 and 55 trucks. Nothing I found matched completely. A 2003 C series brochure shows an LB7 engine and M50 6 spd. My '03 has an LB7 and ML6 just like Radio's C5500. I could never track down what an M50 6 spd is but looking at the GM Fleet website I found the RPO codes for 03 to 05 trucks. On that site 5500's do not get LB7's but other Dmax engine codes. Obviously a different code for the 230? hp engine. In 05 the codes changed, I'm assuming due to pickup's LLY engine.

I'm not 100% convinced the flywheel / clutch is different. Unfortunatley when I was checking into tracing the part numbers for the 45/5500 factory engine brake I needed a VIN number to work from. Maybe Radio can call his dealer and have them look it up?

I found the M50 code. It's the light duty New Venture 5 speed. That means the 03 brochure I found was total bunk!!!
I was shocked myself. What I was told is that the medium duty uses a 16" single mass flywheel with a 13" clutch and that the 2500/3500 uses a 14" flywheel with 12" clutch. I was also told that the medium duty uses a different bell housing that is integral to the engine, and that it acts as a closeout for several water passages.

Having looked into this further, the two setups, pick-ups vs. MDT, look very different. The MDT is definitely a larger unit, and has mountings for PTO attachments on the driver side (sturdy looking, I might add) that are not present on the 3500 I looked at.

Jeli, I use a commercial dealer in Baltimore, and they are not familiar with the LT trucks (the smallest they work on are the W3500 and the older style 3500HD), so they did not have the parts manuals to do a look up on the C2500/3500 DMax trucks.

If you want to give them a call, their service department folks are very knowledgeable and helpful. Dovell & Williams Truck Center, 1120 Crain Highway, N.W., Glen Burnie, MD
Ph: (410) 766-8132 (select the Service Department from the menu prompt)

Or dial Ext. 105 for my GMC/Isuzu rep, Rick Kramer. He has access to the GM Commercial Dealer network with just about all the information you may want to get an answer for, in other words, if he does'nt know it, he will know how to get an answer for you. These are "truck guys", and a great bunch to work with.

You can also ask about "ship-thru" information on new trucks. Almost any upgrades are available from the vendors D&W do business with...i.e. larger Dana differentials, Air-ride or cab conversions to extended cab, or a Crew Cab with Extended cab conversion for 3 row seating for 4500 - 8500, (real neat looking, and only requires an 84" CA on C4/5 or 102" CA on C6-8), and much more... I liked the 4 X 4 conversions on the C7500/8500s with a 3o0HP / 860#/Ft Torque Cat. with Air brakes...awesome trucks used by tree-trimming companies and by the USMC).

Another thing about the MDT Dmaxes...the engine codes are different, and there are some subtle differences between the MDT and LT 6.6L TDs when you compare the tow side by side. (The 6.6L TD pictured on the site is the one from the LT trucks, and does look different than the one in my C5500).

I ordered the following RPO Codes:

LRM -- 300HP @ 3000 RPM, 520#/FT Torque @ 1800 RPM, 6.6L (403) SPFI, V8, 6600 DURAMAX Diesel Engine -inc: 3250 rpm Governed Speed, 750CCA Dual batteries (Req: KPJ Auto Engine Shutdown & Alarm)
GZI -- GVWR 25,950#/GCWR 29,500# (Req: PTO, ML6, K40, 036, GXA, G80, GN1)
K40 -- Engine Exhaust Brake & Restrictor -inc: elect auto exhaust restrictor (Req: Diesel Engine, K16 Air Compressor)
NPE -- Electronic Auto Exhaust Restrictor (Req: Diesel Engine & K16 Air Compressor) "Used to increase engine heat during warm-up, operates only in neutral".
KA4 -- 1000W Engine Block Heater -inc: cord w/120v plug & plug protector (REQ: Diesel Engine)
TNL -- 750CCA Delphi HD Freedom BS 31-750 Dual Batteries -inc: 1500 total CCA
KG4 -- 150 Amp AD244 Alternator (N/A w/YW2 Option Pkg)
KPJ -- Auto Engine Shutdown & Alarm -inc: oil pressure/water, level/water temp monitoring *Activated by low or high engine oil pressure & high engine coolant temp*
ML6 -- 6-Speed S6-600 ZF Manual Transmission W/0D -inc: deep low, 6-Bolt SAE LH provision, pwr take off, 13" Valeo clutch (N/A w/UXT Trans Temp Guage)
GL8 -- 13500# Single Speed Rear Axle -inc: 2-piston brake applied calipers (STD)
036 -- 4.44 Axle Ratio (REQ: Diesel Engine)
GN1 -- Rear Stabilizer Bar
G80 -- Rear Limited Slip Differential

That's from the Build Sheet. Perhaps some of these codes can provide the answer for you.



Good luck.