3/4 Ton woes...

[Gumby'sC20]

One of the biggest drawbacks to my 3/4 ton is the gearing.

I never use 1st [granny] gear, I always start in 2nd and 4th gets me on the highway, but at too high an RPM for me [and my ole girl's] comfort.

I was thinking a new rear end with different gearing, something I could go to the junkyard and pick up, may remedy the issue. I'm wondering if this would help and what rear end I should be looking for.

Also, the 4 speed may be part of this issue as well seeing as how it also, is geared quite low. I may be looking and replacing this too, in order to get the truck to be a smooth highway cruiser. I was pondering an auto conversion (or sticking with a manual if I could get a 5 speed or get one that would keep the revs down at speed.) What should I be looking for here?


Thanks in advance guys. Glad to be back on the forums again!

[VanceH]

Same for me. The rear end change seems to be the easiest and cheapest. The new auto tranny is what i am going for very soon. So far I have been told that you need a new crossmember and either a new auto column or custom shifter.

[UltraBlue71]

Hi gumby I have the same issue!Does your truck have a dana 60? From what I have learned by posting a similiar thread "highway screamer" the danas ring and pinion can be changed, but the eatons cannot, I have a 4:11 too, I guess a 3:73 is the way to go. A gear splitter would work great in setups like ours too but they are spendy. The NV4500 (in 90's chev trucks) 5 spd is a hyd clutch trans, so lots of info on that on here too. Also I here the trans from F-body T/A Camaro will work on these too, lots of mods either way. Ya might want to start with new gears (a few hundred bucks) and see if that will work for ya. Just a .2Cent input from someone who knows where you are coming from.

[Ryan Hubbard]

I replaced the gears and differential in my Dana 60 for $600.00. I put in a Detroit Locker and 355 gears and the whole unit was rebuilt for the price. Definitely look into replacing the gears.

[mrein3]

Originally Posted by UltraBlue71

Hi gumby I have the same issue!Does your truck have a dana 60? From what I have learned by posting a similiar thread "highway screamer" the danas ring and pinion can be changed, but the eatons cannot, I have a 4:11 too, I guess a 3:73 is the way to go. A gear splitter would work great in setups like ours too but they are spendy. The NV4500 (in 90's chev trucks) 5 spd is a hyd clutch trans, so lots of info on that on here too. Also I here the trans from F-body T/A Camaro will work on these too, lots of mods either way. Ya might want to start with new gears (a few hundred bucks) and see if that will work for ya. Just a .2Cent input from someone who knows where you are coming from.

That depends on what you consider is highway speed.
When I'm on the county highways and US highways, speed limit 55, 373s with stock height (28") tires, my engine is spinning at 2800 - 3000 rpms. Not screaming but a tad fast.
What I consider highway speed - 70 mph on the interstate - well lets just say overdrive would be nice.

IMHO, 373s or 411s with overdrive - either manual or auto - is the way to roll.

[Shyguy]

The 4 speed transmission should not be a problem with how many rpms the engines is turning because as far as I know in 4th it is direct and not under.

I have one in each of my pickups and enjoy them, but I can see how they might bother some. Luckily both of mine are in 1/2 ton trucks with 3.73 gears so top end is better.

The low gear is only used when a lot of power is required, some of the old timers call them stump puller transmissions.

I am sure some old timers can recall using old trucks in the fields hauling hay and having the truck idle in the field in low gear while someone would throw hay on the towed trailer.

You could find a donor 1/2 ton and change out the front and rear suspensions including rear end. This would give you better gearing options and a softer ride.

Danny

[hounddogs!]

The first thing I did when mine came off the farm was go to a 3.54 Dana 60. 30.5" tires have helped.

I haul firewood several times / year, so the granny gear is still useful in my case.

[Gumby'sC20]

I had my hands on a 3.73 a few months ago, but needed to allocate the cash to a different area of life, forcing me to sell it.

Seems the general consensus says change the rear end to a 3.73. This is pretty straight forward from what I can tell and can be had for a few hundred bucks at most. Only issue is going from 8 to 6-or-5 lug, requiring the front to also be converted and new rims and tires to be purchased. Overall though, I have mixed thoughts on this one... hmmm...

[haysonj]

Originally Posted by Gumby'sC20

I had my hands on a 3.73 a few months ago, but needed to allocate the cash to a different area of life, forcing me to sell it.

Seems the general consensus says change the rear end to a 3.73. This is pretty straight forward from what I can tell and can be had for a few hundred bucks at most. Only issue is going from 8 to 6-or-5 lug, requiring the front to also be converted and new rims and tires to be purchased. Overall though, I have mixed thoughts on this one... hmmm...

I know its out of your price range but the Gear Vendors OD is the answer. I have 4.09 gears and cruise 70MPH at 2300. Its around 2000 at 55 which I tow at and I have 6 gears to play with on hills

[Shaky]

My '67 has the SM420 4-speed and a 4.11 geared "eaton" rear.

Just something to think about: if you put in a Dana 60 or 14-bolt with higher (lower numerically) gears, the rpm drop on the 2-3 shift becomes too much unless you have a monster motor.

I love my "granny" first gear and want to keep both the rear and the trans. Therefore, I'm looking at either the Ranger (before the trans) or Gear Vendors (after the trans) overdrive. The Gear Vendors is great since it turns the 4-speed into and 8-speed. It's pricey though.

[UltraBlue71]

At 70-75mph out on the interstate my old truck runs between 3500-3700 RPM, so I dont go that fast, I personally never use the granny gear it might as well be a 3 speed! I wonder if a 3.54 gearset would be the way to go then,hmmmm? I should have changed it before I put that blazer tank in, dangit!

[69GMCLonghorn]

I have an Eaton rear end. The gear options are low and lower (4.10 or 4.56). I have 32" tires and turn 3050 RPM at 70.

If you go the Gear Vendors route, make SURE you have an SM465 and not an NP435 trans like I do. GV does not have an adaptor for the GM version of this tranny. I bought a GV unit last year and ended up sending it back. I thought they didn't know what they were talking about, but apparently others have run into the same problem.

[70rs/ss]

NV4500 all the glory of the SM465 w/granny and an OD to go 70mph, nearly a bolt in deal and can be had cheaper than a gear swap, maybe even cheaper in NY since rust is abound, look for a late 80's early 90's one ton, 5-speed and take everything!!

[UltraBlue71]

Originally Posted by 70rs/ss

NV4500 all the glory of the SM465 w/granny and an OD to go 70mph, nearly a bolt in deal and can be had cheaper than a gear swap, maybe even cheaper in NY since rust is abound, look for a late 80's early 90's one ton, 5-speed and take everything!!

Thats a Hydraulic Clutch Tranny, lots of fabrication inviolved correct?

[69GMCLonghorn]

UltraBlue71, you are correct. It is ANYTHING but a bolt in swap. I never got a price, but had a tranny shop say they could rig up the hydro clutch. But one thing led to another and I was looking at probably $1200 - $2000 to get the thing on the road; that's after finding the tranny itself! I wrote it off and am dealing with the pistons swappin' holes on the freeway.

The fun thing is if I'm doing 65 and someone screws with me, I stand on it, the secondaries open and I'm right in the power curve and moving! Of course, once I hit about 85-90, stick a fork in me, I'm done. But it's a ride getting there!

[70rs/ss]

I belive you can get a manual clutch bellhousing and honestly a hydro clutch is pretty easy and done on many trucks on this board, use the hydro MC and attach it to the stock clutch peddle, pretty straight forward and way better than a manual leg power clutch IMO?