Did a Trans swap in my 82 GMC now have way to many RPMS

[harvnut]

adjust the transfercase shifter i was not aware of a adjustment on them How do you go about doing that ? also is there any way of checking to see if transfercase is stuck in low?The only way I know is to lock hubs and not move shifter and if the 4 wheel is working than the transfercase is not in 2 wheel high.

 

[f1shman]

adjust the transfercase shifter i was not aware of a adjustment on them How do you go about doing that ?

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[crazy4offroad]

is there any way of checking to see if transfercase is stuck in low?The only way I know is to lock hubs and not move shifter and if the 4 wheel is working than the transfercase is not in 2 wheel high.

Leave the hubs unlocked, put it in 1st gear (granny low) and roll along real slow while someone else walks along side the truck looking underneath at the front driveshaft. If the front driveshaft is spinning with the hubs unlocked, it's in 4WD. I'm like 99.9% sure you're stuck in 4-Lo at this point.

 

[HotRodPC]

You're still good. with 37in tires and 4.56, you are at 2900rpm at 70mph. You're running a small block Chev right? Run that dude. SBC loves RPM. And just cuz rpm is high, does not always mean bad mpg either. with the gear and tall tire, that motor is not straining a bit at that rpm. I'd run it bubba, I think you're just not used to it. And as far a running a 3.08 gear ratio.... Hellllllllllllllll NO !!! You may as well shoot yourself in the leg. To turn that tire with a 3.08 you'd kill your motor and clutch.

 

[HotRodPC]

I have plenty of take of and get up is good.I just need to get someway figured out to were I can drop some Rpms on the top end to were I can run my engine and not worry about being to hard on it.with me going around 40MPH my rpms are about 4000-4200

Oh yeah, something is wrong here. That does not compute right at all. Are you sure your tach is set at 8 cyl and not on 6cyl or 4cyl? And your speedo is still connected to the same Tcase, so you know your speed gears are accurate? Or did you change Tcase too? Maybe the wrong speedo gears in the Tcase and you are going faster than you think. I wouldn't swap a thing. Sounds like you have a good set up now, just get the speedo/tach issue accurate and find out if your Tcase is not in 4LOW.
I had a 64 GMC with a Dana 60 4.56 LSD and 31 BFG All Terrains, and I ran 70 all day long with a SBC 327 and 350, and even a 427 for a short time. I never hurt a motor and that is just over 3400 rpm. Ideally, you like to be around 3000 rpm max cruising freeway, but going over isn't gonna hurt a SBC they love rpm better than they do the strain. All my other buddies trucks would slow down to 50-60 mph climbing a hill with a trailer and 2 ATV's on it. Mine held 70mph and didn't strain a bit and begged for more. You'll love it once you get it figured out.

 

[crazy4offroad]

I can say this the transfercase is one that I bought with the trans and I was assuming that It was good

I'd like to see some pics of the t-case, since it came with the transmission it could be a number of different ones. If it's an NP203 it is a fulltime 4wd t-case, and I think the shift pattern may be backwards from the one you had before. In other words if your tag thingy beside the shifter says 2wd is all the way back you may be putting it in 4-Lo, or something along those lines.

 

[HotRodPC]

This also tells me its likley got the wrong speedo driver and driven gear in it so the speedo is lying like a fat kid who cleaned out the cookie jar and saying he didn't.

 

[crazy4offroad]

May be but if he's doing 4 grand on the tach on the highway and everyone around him is passin him like he's sitting still it doesn't matter what the speedo says, he's stuck in 4-Lo.

 

[HotRodPC]

May be but if he's doing 4 grand on the tach on the highway and everyone around him is passin him like he's sitting still it doesn't matter what the speedo says, he's stuck in 4-Lo.

This is true, but I also mentioned for him to make sure his tach is accurate. It may sound like its turning some mega RPM's like 2900 and be showing 4000 or 4200 if its set on 6 cyl or 4 cyl instead of 8cyl. I've seen inaccurate tachs before and that was problem. The guy wasn't aware there was a switch.

Not saying you can't be right, cuz you sure can be. 50 mph w/ 4.56 and 37 in tires and a 2:1 4Low would equate to 4200 rpm. If his truck was originally an NP208 and he's using that shifter for a NP205 or NP203 it's certainly a possibility too. Just saying, make sure the tach is accurate and go from there and if possible to get the speedo correct do that too. I'm just picky that way, I like my **** right.

 

[bigchevytruckdriver]

Definitely in 4 Low imo! I once swapped trannys and stuck the shifter on upside down so all the way back (normally 2 hi) was actually 4 lo. It was an auto and it would actually shifter so fast you couldn't even feel it thought the new trans was junk. Sounds like a similar story to mine!

 

[GreaseDog]

This is true, but I also mentioned for him to make sure his tach is accurate. It may sound like its turning some mega RPM's like 2900 and be showing 4000 or 4200 if its set on 6 cyl or 4 cyl instead of 8cyl. I've seen inaccurate tachs before and that was problem. The guy wasn't aware there was a switch.

Not saying you can't be right, cuz you sure can be. 50 mph w/ 4.56 and 37 in tires and a 2:1 4Low would equate to 4200 rpm. If his truck was originally an NP208 and he's using that shifter for a NP205 or NP203 it's certainly a possibility too. Just saying, make sure the tach is accurate and go from there and if possible to get the speedo correct do that too. I'm just picky that way, I like my **** right.

the figures are too consistent with being in 4 Lo... if it is the tach, its a HUGE coincidence.

furthermore, mating a 700 to a 203 or 205 is not cheap at all. if someone were to swap to either of those cases, you'd know it... the price would be ridiculous.