ozob nospej

I'm new to the forum, so this may be a repeat. I've got a '98 5-speed 2500 4x4. I just got a new truck, but I'm keeping my old one too. Were an all Cummins family. The '98 is one of the early of the 24 valves. My 5 speed has served well for 250,000 miles, but I'm ready to upgrade to a 6 speed and refurbish the truck. Someone here has done this I'm sure. I would like suggestions on the "right" parts, clutch and mods for this conversion. The engine is going to see some upgrades so I want to make everything as bulletproof as possible. This will be a daily driver. It will see towing of up to 15k pounds too. The RER is 3.73? I think. I'm not a part number kind of guy about the trucks so steer me in the right direction. Any help will be appreciated. One other thing, I know this kind of post can result in a laundry list of possibilities, but my buget is NOT unlimited, comments about pricing and where to find things is appreciated.
Bill Jepson

Captain

I've done it and it was the biggest waste of over 10000$ ive ever spent and 7 months of my truck not running. in my opinion the 6speed is junk. Its apprently not really any stronger then a 5speed built with a larger input and fully splined main shaft. Costs 3 times more to buy and to rebuild. If your on a budget I'd suggest not down gradeing to a 6speed. You can get a complete rebuild on a 5speed + large inputshaft and fully splined main shaft for 1500-2000. Clutch wise go SBC single or double, whatever your mods, use/abuse, and wallet can handle. If you do feel the need to put a 6speed in expect to pay for the cost of the 6 speed + another 600$ or so for parts. You need the trans. From the dealer you need an exhaust bracket, shift tower, screws for tower, isolator for tower, steel screw grommets and shifter **** indicator. Also you need the conversion kit avilable at quad4x4.com. I also suggest getting a DSS and 03 trac bar conversion. performancedieselwarehouse.com has those. Some people prefer other brands of aftermarket trac bars. There all good just get the one you like. But get something, the stock ones are an accident waiting to happen. Also fill out your signature so we know what you have allready. You'll want an EGT gauge too at a minium esp if you want to tow. Keep in mind that your towing because that will limit your mods or get expensive real fast to keep things cool.

blackdiesel

I think that said it all, captain! do you really need another gear between 3rd and 4th that bad?

gmctd

NV5600 benefits -
- 2.5ton\equiv trans, weighs 390lbs, dry
- heavier duty - all shafts, gears, bearings much larger than NV4500
- spreads between gear ratios are evenly spaced, keeps rpms in max torque range for Cummins, excellent for towing, esp stop-start towing
- 6th overdrive is at front of trans, no loss of o\d, ever

NV4500 weighs 190lbs, dry

NV5600 dis-benefits -
- 2.5ton\equiv trans, weighs 390lbs, dry
- 6th o\d is at front of trans, more difficult to down-shift into all lower ranges
- ditto, difficult to shift into 1st or 2nd when stopped
- shifter is vague, notchy
- reverse-configuration of gear train reduces speed-shifting for drag-racing
- precision clearances demand special lube, very expensive
- difficult to service -
-- requires special jigs, fixtures - some can be home-made, some not
-- bellhousing is front-bulkhead for gearcase - remove entire case from gear-train to service
-- case weighs ~150lbs
- out of production since ca'04\'05, some bearing and synchro kits still available

Need the '99-up rear crossmember, driveshaft and yoke is same, uses same clutch cylinder, 1.250" input can use standard clutch\flywheel, 1.3750" input requires 13" flywheel and clutch - are some 1.3750 conversion clutch disks for standard 12.250" clutch\flywheel.

I like my conversion, but not for everyday stop-go traffic, at my age - I've begun starting in 3rd to ease up on the shifting - little more mechanical effort with the 3.54's, but the driving experience is more equitable, not as much personal effort.

Does sound like a mini-18wheeler when rowing thru all 6 gears tho - rev up to rpm, even drop between ranges at each shift - puts a smile on yer face for a while

Depending on who's watching, I'll still row thru all 6 speeds, show'em what they're missing with their wimpy five-speeds

ozob nospej

Nope, I would like better splits, but not that bad. This makes the Gear vendor sound really good. Could anyone direct me to a good rebuilder for the 5 speed? A secondary question. My 5 speed has had a shake/rattle in 5th from day one. This may be an oooold question. It this typical? Doesn't seem to be a functional problem. It has been doing it more or less since we got it. Seems to be like a shifter linkage noise. I'd love to get rid of it.

Captain

neither of my 2 98's ever had a 5th gear noise untill high millage. The one truck we just took the 5 speed out of with over 350k miles on it and the stock clutch. That had what you may call a rattle. A bearing rattle is what I'm pretty sure it is. Also many 98's have a crossmember you can use for a 5600swap. If its the 11" wide one your good to go. I have sent my 6speed (twice) and 1 5speed (other is on its way) to bluemanthals in oklahoma. Even with the cost of truck freight both ways its much cheaper and a better quality job then I can get locally. The 5speed though isnt to bad to rebuild so check around locally if you want. Otherwise I'm very happy with what bluemanthauls has done for me. www.blumenthalautomatics.com if your getting a new clutch you might want to think about the larger input shaft. The smaller one may or may not break after lots of millage towing heavy. Also while its out I got the fully splined main shaft and updated 5th gear nut. Should help prevent 5the gear from falling off.

Rodram2002

I'd stay with the 5-speed. There is a big shortage on 6-speed parts if that thing happens to take a crap on you. A lot cheeper to fix your 5-speed I would think.

Captain

bluemanthuals bought NV's 5600 tooling and shiped it to the place that makes eaton's parts. So they can supply you with new as close as you'll get to OEM parts. However there probbaly the only ones and its still way expensive.

gmctd

That's good news - altho I had nabbed some NOS stuff off ebay for posteriority's sake............

BCB

i made the swap and i would hate to have to go back... I had no problems finding parts... Quad 4x4 and bluementhuals had everything i needed... i love it for towing and just regular driving, theres a gear for everything! if you have any guestions shoot me a PM.

RonA

I switched my first gen over to a six speed and have never wanted to go back. I had the getrag with a gear vendors, and then put the 5600 in with the gear vendors. I took the GV out because I did not need it once I brought the hp up a bit. I am switching to an auto soon to save wear and tear on my left knee. I'm sure i will miss it when I tow.