Engine/Transmission (1994 - 1998) Redline questions

[AndyJohnson]

I had a 98 2500 12v 5 spd with 3. 83 rear end or 3. 88 don't remember witch. Also 265 tires, still stock. it would max out 3100 at about 110mph on the flat. My new truck is a 98 2500 12v 5spd but with 3. 55 rear end and also 265 tires. Afc and plate forward and straight exhaust for the most part all stock. But at 3100 on the flat also only runs about 95 to 98. Does this make sense to anyone? Need some ideas about what might be wrong.

 

[McCRam]

My 97 with 3. 54 gears won't break 100 either. I would guess at a speedo error In some form on your previous truck. Were the 3. 8? gears factory? I didn't know that they were an option if they were. If they weren't, the speedometer might not have been corrected properly. Just my idea.

 

[AndyJohnson]

thanks for the reply. It was i think 3. 83 but it was for sure right about there it was stamped on my door tag. And my spedo was on because i had a gps on to make sure. Because after i put on 35 and could hit about 120 on gps. I think its my gov. springs

 

[AndyJohnson]

97 is also the getrag trans. my brother had it the nv4500 is higher geared and 5th runs longer.

 

[zstroken]

97 should be NV4500

 

[AndyJohnson]

Really, i thought everything before 98 was the getrag. I know my brothers 97 was

 

[zstroken]

Your brothers transmission wasn't stock then.

 

[AndyJohnson]

so what year did they quite using the getrag?

 

[zstroken]

I think 93, not for sure

 

[AndyJohnson]

Oh i was way off then. So what is the difference on like 95 to 97 that cause the nut to spin off of 5th gear where as on the newer 98 and newer the shafts break. I was under the impression that the transmissions with the problem of the nut falling off was the getrag and the new ones with the shaft breaking on 5th gear was the nv4500. so it just a different design in the transmision?

 

[DBogo]

the 97 and up 5th gear nuts can fall off too

 

[Matthug]

The nut doesn't fall off (or has a WAY less likely chance) if you don't run in 5th gear below 1600 RPM especially with heavy throttle. 94' was the first year for the NV4500, thats what mine has. It also has 255K miles original trans, never had a problem with the nut falling off even with my power level because I never lug 5th gear.

The only gear options I'm 99% certain from the factory was 3:54 or 4:10's. With 3:54's I hit about 110-115 at about 3100 RPM. The carrier was different between the two gearings also, I've never seen aftermarket gears in between 4:10 and 3:54. Personally, I'd like the change to something like 3:21 gears!

 

[zstroken]

You can get a 3. 73 they make a thin 3. 73 for the 3. 54 carrier and make a 3. 73 gear for the 4. 10, it could be the other way around. If you don't tow, a lower numerical gear could be great, the cummins could sure handle it! If you have the dana 70 I think the cut off for the carrier is 4. 10.

 

[Matthug]

I tow once or twice a year, and only 8000 lbs. I have a D80, not sure if they make 3:21's I doubt it. But I think with 3:21's it would still handle 8K pounds, plus I'd get better highway mileage too.

 

[Matthug]

You can get a 3. 73 they make a thin 3. 73 for the 3. 54 carrier and make a 3. 73 gear for the 4. 10, it could be the other way around.

You have it the right way. The lower (numerically) the gearing the larger the pinion is, so it would require a thinner ring gear.