What are the real world hp/torque limits for the Spicer 6000's for highway use at full load?

[hethead]

I know I found the specs for max input torque once... but I can't find them now. I'm turning up my 250 and I'll be pulling a 30k trailer. I was wondering if any of you who have already tuned up their 855's or swapped them out for a bc350, 400, etc. are still running the 6000 series Spicer and have found the limits first hand. I've found some Spicer main gearboxes that have 3 different torque ratings for off road, highway and interstate duty.

Actually, I'd even just appreciate the factory torque rating from Spicer or anyone breaking it period.

Thanks in advance.

 

[simp5782]

I know I found the specs for max input torque once... but I can't find them now. I'm turning up my 250 and I'll be pulling a 30k trailer. I was wondering if any of you who have already tuned up their 855's or swapped them out for a bc350, 400, etc. are still running the 6000 series Spicer and have found the limits first hand. I've found some Spicer main gearboxes that have 3 different torque ratings for off road, highway and interstate duty.

Actually, I'd even just appreciate the factory torque rating from Spicer or anyone breaking it period.

Thanks in advance.

A big cam will tear it apart for the most part. Somewhere around 800ft lbs as it's a medium duty transmission.

You can bump the NHC250 on upwards of around 300 with no problems.

Big cams prefer an sae1 housing over having to redrill the sae 2 housing for the big cam off set bolt. Medium duty transmissions are always a 2 pattern. Sae 1 bellhousing requires new engine mounts in the rear.

 

[hethead]

A big cam will tear it apart for the most part. Somewhere around 800ft lbs as it's a medium duty transmission.

You can bump the NHC250 on upwards of around 300 with no problems.

Big cams prefer an sae1 housing over having to redrill the sae 2 housing for the big cam off set bolt. Medium duty transmissions are always a 2 pattern. Sae 1 bellhousing requires new engine mounts in the rear.

Thank you! That answers my question. 800 ft. lbs. is enough for me. I was only planning on around 300 hp anyway (due to the transmission), so that firms up my target as I gather parts.

Thanks for your time.

 

[hethead]

Thank you! That answers my question. 800 ft. lbs. is enough for me. I was only planning on around 300 hp anyway (due to the transmission), so that firms up my target as I gather parts.

Thanks for your time.

In my Land Rover, 4th gear in my main gearbox is the strongest gear in the sense that it goes right in one end of the gear box and out the other, one to one on the same shaft. The layshaft (counter shaft) isn't involved in that gear so it's capable of much more torque. I put an intercooled turbo diesel in it with much more torque than the original engine so I stay out of the boost until I get in 4th/4th over drive. Or at least I try to. Is one of the gears in the Spicer that way? Where torque inputs and outputs on the main shaft without loading the countershaft? That would allow me to turn the 250 up a little higher to maintain some speed on the hills. For some reason I feel like it loads the counter shaft in all gears.

 

[simp5782]

In my Land Rover, 4th gear in my main gearbox is the strongest gear in the sense that it goes right in one end of the gear box and out the other, one to one on the same shaft. The layshaft (counter shaft) isn't involved in that gear so it's capable of much more torque. I put an intercooled turbo diesel in it with much more torque than the original engine so I stay out of the boost until I get in 4th/4th over drive. Or at least I try to. Is one of the gears in the Spicer that way? Where torque inputs and outputs on the main shaft without loading the countershaft? That would allow me to turn the 250 up a little higher to maintain some speed on the hills. For some reason I feel like it loads the counter shaft in all gears.

You aren't going to maintain much speed without a turbo. I ran a #16 button. 215 rail pressure. Dual line, restricted return. Ram air intake with 1400cfm filter with no turbo. It lasted quite awhile before I had issues. Over 225k miles. I went thru an Allison mt654 every 30k miles. I then went with a cat 16spd behind it.

 

[hethead]

You aren't going to maintain much speed without a turbo. I ran a #16 button. 215 rail pressure. Dual line, restricted return. Ram air intake with 1400cfm filter with no turbo. It lasted quite awhile before I had issues. Over 225k miles. I went thru an Allison mt654 every 30k miles. I then went with a cat 16spd behind it.

I remember your truck. I've asked you quite a few questions over the years as I've tried to learn from your experience (and I've appreciated it!). I'm putting a turbo on with a little boost (10 lbs or so) an intercooler and shooting for around 200 lbs rail pressure. EGT gauge of course. If I melt a piston it'll give me an excuse to do an in frame with some lower compression ones and start searching for a rebuilt gearbox . It's slowly coming together. I just bought the truck I'll be using for the cab and I'm collecting parts when time and life allows. This is just a retirement toy for me, so it won't have to work for a living. But I'll be doing a lot of miles. 7,000 just last month in the diesel Rover and I'm itching to get back on the road again in the big one.