My CUCV story!

[NCINIRATOR]

HI all, I was waiting for some time till the forum came back online to post. I purchased a CUCV from GovLiquidation back in February. I drove right off the lot. It died on the way home. Both alternators croaked, in turn frying the batteries. I got it towed to my buds house in Hagerstown.

I purchased a alternator from autozone (BIG MISTAKE!), they gave me the wrong one twice. On the third go round with em they looked up my vehicle on a school bus code and gave me a alternator that looked exactly like the original. I attempted to install it and as soon as the alternator touched bare metal I got a pyrotechnic show from the fusible link. Knowing NOTHING about diesels I gave up and had it towed to Warren Martins garage down the street. Those guys treated me right, from them I learned that the original alternator was grounded (shielded?) from the system and that what I got from autozone was not, so that explained stuff exploding in my face. They rebuilt the crap from autozone and rebuilt the second alternator. [complaining]

Oil change and thermostat change (just in case) and I was set.

I also found out that the light bulbs in the dash for the generators are fuses, one was burned out.

My CUCV does not smoke when I start it and starts/runs just fine. The tranny slips a little though.

If any one knows the answer to this question- can a 4 speed tranny work in it? And, if I wanted to change the rear end out to something for more highway/better gas milage what would the gear ratio be?

Thanks any information, and thanks to all who have the knowledge that share it with the rest of us newbies to the CUCV family.

 

[NCINIRATOR]

OH yeah, my fuel needle took a while before it read full after I filled it up, about 12 hours to be exact. Where is the problem with a bad fuel reading? Behind dash? fuel line? in tank??

Mount Rainier, Maryland

 

[85-m1028]

If by 4speed you mean 4sp. auto then yes you can swap in a 4l80e or 700r4, I have often pondered this myself when I got my truck, here what I concluded, the turbo 400 you have in there now is a pretty stout auto used for heavy duty applications, this 3 speed combined with 4.56 diff gears makes for a dog on the open highway, the solution Bigger Tires!! , with a small lift kit and say a set of 37" tall meats makes for a much meaner look and way better daily driver. If your tranny is slipping a little I would check the vaccume pump mounted behind the intake manifold and the vac hoses and replace any thing that looks cracked or leak prone, "my vac pump was shot and hoses were rotted" The cost of a new set of gears and a tranny swap will usualy cost way more than a lift and some tires. besides 5800 pound truck sittin on some pizza cutters will tend to loose traction even if you are locked in the diff. :smilewinkgrin:

 

[NCINIRATOR]

I`m kinda diesel ignorant. Never owned on till now. :eyes: Enlighten me on why bigger tires instead of taller gears or another tranny. Taking a guess at it I would think that biger tires means you travel more distance with every rotation that a smaller tires. But I dont want something that sits that high off the ground and of all the solutions to the low gearing on the CUCV's I never heard of justing switching to bigger tires.


how did that work out for you, pro's & con's.

 

[mouse]

take a dime and put it next to a quarter. the dime is your gear and the quarter is your tire,now rotate the dime and count the number of rotations the dime makes to one of the quarters rotations.do the same with two dimes, this would be = to a 1 to 1 . so the smaller the tire ,the better top end ,and the larger the tire the better the torqu. there is a formula for this,but i dont have it, so call your local hot rod shop ,they will tell you.one more thing if you change your tires dramaticaly,change your speedo gear in your tranny.if you dont your speedo will be off. []

 

[85-m1028]

with a three speed auto third gear is a 1 to 1 ratio which means the transmision output roughly matches the engine rpm, (engine @1000 rpm the tranny in third gear will be spinning the driveshaft @1000rpm) the optimal engine rpm for the 6.2 diesel at 60mph should be between 1800 to 2800rpm. Here's the formula, stock tire height is about 32" tall, (32" tire with 4.56 gear ratio differential @ 55mph will have the engine spinning at about 2700rpm) "this is the what the military top speed limit rating is" so if I go with a taller tire here's what you get (35" tire 4.56 ratio = 60 mph at 2700rpm) *the closer you get to 1800 rpm will get you better fuel economy but sacrifice pulling power, 2800rpm good pulling power poor fuel economy, so the target rpm is usualy right in the middle which would be 2300rpm. so now you have to decide your top cruising speed and what size tire you need to get you there while maintaining 2300rpm, I run 35" tires on the old worn out stock suspension with minor fender trimming, but I will eventualy get a 4" lift and I should be able to run 37-40" tires which would cost about $2000 if you can get 4l80e trany with computer to make it work for that price than you d man, but your'e still sporting those stock pizza cutter tires, but it would be running a cool 2000rpm @ 60mph with 4.56 gears (http://www.ring-pinion.com/content/calculators/RPM.asp see if this works for you!!

 

[NCINIRATOR]

Sooo, bear with me here, changing the tranny out with a 4sp will only give me that cruising gear(OD) becuase the 3rd gear will be a 1-to-1 ratio. I should go with taller gears in the diff (411) and bigger tires to lower my rpms, yes?


So what if I slapped in a 4sp tranny and different gears in the diff with out messing with the tire size?



Better yet, the ultimate question is- Whats the cheaper way to go?

 

[85-m1028]

well if you could swap in a 4l80e (this is a turbo 400 with an overdrive) you would need a computer wired in to make it work, there are some company's that make stand alone computer modules to tell the trany when to shift,"the E in 4l80E stands for electronic" but I am not sure of the cost involved. I saw a company on e-bay motors that sells them and can fix them up for you "I think I even read something about manual valve body" take a look just type in 4l80e. Then you really wouldn't need to change out your diff gears with an overdrive transmision. but the question is whats the cheapest!!, well ok I guess swapping out your diff gears to a set of 3.73 would work best with 32" tall tires and keep the turbo 400, that should net you top speed of about 65-70mph and still keep some power and fuel milage. "any thing below 4.11 and I think you need to change out the carrier, but getting a set of 3.73 gears and a carrier from the salvage yard should be an easy find!!

 

[NCINIRATOR]

When you say change out the "carrier" you mean the rear axle right?

 

[85-m1028]

no I mean the thing that the ringgear bolts to, in the rear this would be the gov locker and front it would be the part with the spider gears.