The Stovebolt Site Forums The Shop Area Engine Shop 5 speed - convert to 5 with "granny"

I currently have what i believe is an SM420 - 4 speed behind the 350.

i'd like to have a 5 speed, but pull a boat and a trailer, so i like a low 1st gear - which leads to my question -

any one try a later model 5 speed out of a 3/4 chev? if so, what little stuff did you run into?

I added a Gear Vendors auxillary tranny to my sm420. Now I have a 7 speed truck. It is the ultimate for hauling.

interesting...have a link for them?

edit - found the link and they seem to be decent monitarily - dependant upon how must bs you have to change..

did they work well for you?

Avette,

The Chevy and dodge pickups run a New Venture NV4500 5 speed. This is a transmission that came about by the merging of the New Process plant, and the Muncie plant... it was a "joint venture" between gm and dodge.

There are subtle differences in the transmissions from year to year, and some versions swap eazier into certain applications. You will almost certainly need a new bellhousing, or adapter plate unless you could find the 93 chevy version. Only the Dodge 2wd version from 94-97 can be ran with a mechanical speedo. The Dodge version has an input shaft that is 1 inch longer than the chevy version. Adapter plates are available to mate them to the chevy bellhousing so you won't have to mess with your clutch linkage.

There is also the possibility of finding a used 1 with the gear venders overdrive. That setup would give you a 10 speed.

so, if a guy went the new venture route, a bell housing and drive shaft would likely be in order - no big deal... i'm a bit curious about linkage, and all the little stuff as well?...

leaning towards the gear vendors idea right now..

yeah, and probably an electronic to mechanical speedometer adapter to.

I chose to use one of these in my 1940 gmc project because I was swaping out my 4 speed crash box and torque tube and needed to use my factory bellhousing for the clutch and brake pedal mounts. I am also running 4.11 gears which turn into a 3.00 in overdrive. I think the best you could get with a Gear Venders unit is a .8 overdrive, or a 1.25 underdrive.

With 3.90 gears, the gear vender final drive will be 3.12. With the NV4500 it will be 2.85. That would translate out to about 220 rpm difference at 65 mph

The Gear Vendors unit pretty much bolts right on your 4spd. If I remember right, is a .73 O.D. I do know that at 65 I go from about 3200rpm in 4th to about 2400rpm in 4th over. I believe my final drive is equivilant to a 3:08 rear? The extra stuff was that I had to modify my torsion bar crossmember for clearance(probably not a problem for you), shorten the driveshaft, and add a new crossmember for the provided mount on the adapter between the units. I also had to wrestle with their phone techs who gave me a lot of attitude when I told them the 1st coupler they sent didn't fit. After some arguing, I got them to send another. Low and behold, it fit. The wiring was so simple, I could do it. Here are pics. http://rides.webshots.com/photo/2234118210071636143MfdrhX

I stand corrected... gear venders has a .78 overdrive. Us gear uses a .8 overdrive. The NV4500 a .73 overdrive.

Not trying to favor any overdrives here, just trying to give you some info.

You will need a new speedo cable for the gear venders OD.

The SM420 has a 7.05:1 1st gear. The NV4500 has either a 6.34:1 (early chevy) or 5.61:1 1st gear.

Most NV4500s... early chevy excluded... are fully syncroed. The SM420 is not syncroed from first- second.

I'm just a poor old retired dude so the prices that I saw at "The Gear Vendors" site kind of shocked me. Maybe I was looking at the wrong thing, but on the average, $3000 plus another 7-800 for drive shaft, is that right???
Denny Graham
Sandwich, IL

The unit is 3k. Just one of the reasons I have 2 jobs. The driveshaft cost $225., balanced, painted and w/ new U-joints. They provide an adapter for the speedo so I didn't have to get a new cable, but I did since mine was due to be replaced. I got a shorter one which does fit better. The synchro really isn't needed between 1st and 2nd since 1st is rarely used. When it is, I'm going about 1-3mph up a ramp or a hill.

Thanks gents.

I install a US gear unit in my RV behind a TH400,,cost was a total of about $1200 with all mods done,,that is doing all labor myself other than driveshaft...doc PS it worked very well...

That,s good info Bad Daddy. Where does the 3500 come in?

I never took a second look at the NV3500 because it has an integral bellhousing... the 4500 was eazier to adapt. I believe I have one in my 2004 wrangler, and it shifts pretty well, but is a little noisy in 1st gear.

The NV3500 is a lighter duty transmission probably pretty similar to the t-5 in capacity and gearing.

The NV4500 is a toploading 5 speed with the shifter being about 10 inches from the front. It would move the shifter back about 3-5 inches from stock for the sm420 and other toploading 3 and 4 speeds.

Would one of those gear vendor overdrives work on a bigger truck as well? I have a 2 ton, looking to rebuild my brown and lipe overdrive. So your subject caught my interest, comparing pros and cons. My truck has the sm420 4 speed to, found that out on this sight to. Also I have the 2 speed rearend, vacum type. My truck weighs 6,000 lbs.
I can run 52 mph on flat ground at 2,800rpm with the brown and lipe overdrive, wonder what the gear vendor unit would do? and would it be tuff enough to handle weight of the truck? I only haul light stuff - model T or motorcycles. Appreciate your thoughts, thanks Tom.

The gear vender units are rated for about 35,000 lbs. 6000lbs for the truck and 19,000 for a trailer. Not to shabby!