The Stovebolt Site Forums The Shop Area The HiPo Shop NV4500 Transmissions

I gotta admit, I'm too lazy to read through all 165 pages of this forum, so maybe someone can tell me where to go. (That happens frequently)

Anyway does anyone have any info on interchangability of NV4500 to the older SM420, for instance? According to one thing I read, it appeared that some early 4500's had the standard bolt pattern to allow direct bolt up to the old bell housings. Conversely, it appears that all the later 4500s have the Dodge bell housing bolt pattern. Any info or direction to applicable reference material would be sincerely appreciated.

I realize drive shaft work might be involved, as well as throwout bearing hassles, but those are to be expected.

No NV4500 will bolt directly to a sm420 bellhousing.

My preference is to use a 1994-1997 dodge 2wd NV4500 for the swap. There are 2 main reasons for using this particular incarnation.

1.) The pilot shaft of the dodge transmission is 1 inch longer than the pilot shaft of the gm transmission. This allows you to use a 1 inch adapter plate between the bellhousing and the transmission. **NOTE** Advance Adapter sells an adapter plate that will work, but it requirs additional maching to go on a sm420 bellhousing. Either the bellhousing will need to be bored out to 5.125 inches, or the adapter plate indexing ring will have to be turned down to 4.686 inches.

2.) The 94-97 dodge 2wd transmission has a physical speedo gear on the tailshaft which drives a pulse generator. The pulse generator can be removed and a standard Mopar speedo drive housing can be installed in it's place with a variety of speedo pinions. The 94-97 2wd version is the only one that allows you to run a mechanical speedometer. **Note** this is a moot point if you are building a 4wd, as the speedo pinion can be placed in the transfer case.

Now there are 2 types of 94-97 dodge NV4500 transmissions. A heavy duty diesel version with a 1.250 10 spline input shaft, and a standard duty version with a 1.125 10 spline pilot shaft. The later 1.125 10 spline matches the gm clutch, so that one is more desireable. The heavy duty version can have the bearing retainer and pilot shaft swapped out without getting into the transmission... adds about $200 for new parts.

The dodge bearing retainer is too fat for a gm throwout bearing. There may be a crossover throwout bearing that works with the dodge bearing retainer and the gm cluch fork. I chose to turn the snout of the bearing retainer down on a lathe to match the diameter of the snout on the sm420. I don'y remember the exact numbers, but I believe it was about .060 needed to be cut. Take your own measurements.

The only other obstacle was the pilot bearing/bushing. The tip of the sm420 is .590 inches. the tip of the dodge nv4500 is .750 inches. I ordered a bronze bushing from AA. The pilot bushing is the only non original clutch component I am using. The pressure plate, disc, and throwout bearing are the same as the gm spec for my truck.

The swap will move your shifter back about 6 inches.

I did the swap on a 1959 gmc 1/2 ton v8. The swap is pretty much the same for a 6 cylinder, however the 1955-1959 gmc 6 cylinder transmissions sit about 4 inches further back as compared with a gmc v8. I believe the gmc v8 sits about 4 inches forward of a chevy engine (V8 or inline 6) in the same years. Moving the shifter back 4 inches will put it pretty close to the bench seat. The shifter handle may have to be bent to clear the seat.

Thanx a million for the info. I knew someone had tried it, just didn't think it was such an involved process.

Not meaning to hijack your post, but I have questions on the Part Numbers for the NV4500's. I purchased a 5sp, but the numbers do not match the #s available on another site. I have 3 trannys and all of the numbers start with 13-38... for example, one complete # is 13-38-007-901; and the others are very similar, starting with the 13-38. Could these be the smaller NV 4500 you are referencing? the input is a ten spline 1.125 diameter.
Thanks!
Keven (inuke)

NV4500 transmissions are very large light duty truck transmissions. They are about 200 lbs without oil. I suspect you have T5 transmissions that could be from any number of donor vehicles. The T5 transmission from s10 pickups is a popular swap in light duty stovebolts. It is a near bolt in. The NV4500 referenced here is a heavier transmission that is more suitable for 3/4 and 1 ton trucks, or high powered v8 trucks.

As a matter of passing, the early GM NV4500 transmission SHOULD bolt to any Chevy bellhousing that came originally equipped with an SM465. The first NV4500s are a direct replacement for the SM465.

best wishes,

Les

Everything I have read on the internet contradicts this statement. I have not seen a 1992-1995 chevy NV4500 in person, nor have I tried to mate one to an sm465 bellhousing. The sm465 bellhousing is the same as an sm420 bellhousing, with the major difference being the large round opening is larger on an sm465 housing.
sm420 is indexed to 4.686 inches
sm465 is indexed to 5.125 inches
Early Chevy NV4500 is indexed to 5.125 inches but reported to have its own unique mounting pattern.
Later chevy and all dodge nv4500 transmissions share a common bellhousing mounting pattern and are indexed to 5.60 inches.

I did a little more reading...

Apparantly the early NV4500 can be mated to the sm465 bellhousing without an adapter plate.

However it requires drilling and tapping new 1/2 inch 13 thread holes in the front of the transmission.

Other issues also need to be addressed if electing to go this route.

Only if you use the Dodge pattern transmission. The first two years carried the Chevrolet bolt pattern and folks now think that is unique. I have fitted an SM465 bellhousing to an early NV4500 and it appears to be a direct bolt up! Most everyone who uses the NV4500 puts them in off-road 4X4s. My intent is to use the early NV4500 as it was meant to be used, in a 2 wheel drive highway truck, so I don't have to worry about transfer cases, crossmembers, and hydraulic clutches. The mystery "unique mounting pattern" has been common to Chevrolet trucks for years, but not to Jeep or Dodge based rock crawlers, at whom most on line information is aimed.

RM,
Thanks for the info! I've done the swap with the 2wd dodge transmission in my 59 gmc for a 2wd highway truck. Looks like another case of the internet lied to me. It also looks like I have repeated this lie. My apologies go out for any misinformation I have spread.

I would still like to see the early chevy nv4500 and the sm465 together to remove all doubt.

@bigbadswingdaddy, You were the one who convinced me to go with a heavier tranny than the T-5 for my 3/4 T panel, so I started reading on line, too. I had a step up on you though, since I'd already done a BUNCH of bellhousing research. It will be Spring before I do the swap into my '69, but to hold you for now, check the part numbers on available bellhousings from 1991 through 1993. If you find even 1 number with the 5 1/8" hole the same through those years then it'll work. All sbc (including V-6) fit the same bellhousing bolt pattern through the mid 1990s, thus they all fit the modern inline 6s as well. The SM465 was used from 1968 through 1992, so if an SM465 fits so will the early ('93-'94 only) NV4500! I meant you NO disrespect but I'm staying pure Chevrolet so things pretty much have to fit. I'll be able to order a stock clutch pack for my model year, too, because the early NV4500 that I have has a 10 spline shaft!

best wishes,

Les

Here is a page on the SM465. at the end it says that GM transitioned from the 465 to the 4500.

http://www.advanceadapters.com/tech-vault/gm-sm465-general-information/

best wishes,

Les

No disrespect taken! Thanks for opening my mind to new possibilities. As they say, there is more than one way to skin a cat.
John

Hello all! I'm new to this conversation, but am needing info on switching from my SM420 to the NV4500 in my '65 C-10.

My understanding from reading and asking an old-school transmission guy is that they will bolt directly up to my bell housing on my 283. He also told me that the NV4500 used an hydraulic clutch, but that it operated externally, so I could adapt my existing clutch and mechanism to it, getting rid of the hydraulic version. Are these things true?

Also - I have access to a 1995 NV4500 for a reasonable price, but I believe that that version did not support a mechanical speedometer. Is that true, and, if so, can it be converted, seeing as how I do not want to alter my dash cluster.

Thanks for your help!

4500's use a mounting bolt pattern that looks just like an earlier GM pattern, however it is slightly larger. One way to get around this problem, is to drill and tap the earlier pattern in the front of the 4500, easily done, especially if your trans is apart. Just sit the 4500 on a bellhousing, tail up. Use a transfer punch to locate the holes, remove the trans, drill and tap the holes. Best to make the bottom ones blind to avoid a bath every time they are removed.

Ed

I just finished an M465 to NV4500 conversion on my 1978 GMC 2wd R3500 dump truck and can shed some light on this swap. I used a 1995 4500 out of an R3500HD 2wd but did not want to convert my truck to a hydraulic clutch as the hydro assist pump system for the brakes (which works great with heavy loads) took up all the firewall room. The 1995 NV4500 does NOT bolt to the M465 bell housing, bolt pattern is wider and actually goes beyond the confines of the original bellhousing. I used a steel Lakewood scatter shield, used a boring bar to turn the guide hole to fit, drilled and tapped the bellhousing to the 4500 and backed up the threads with welded bolts. I used the original 40 lb. flywheel, new original 10 spline 12 inch clutch and did not modify the bellhousing in any other way, tranny flange to block is the same between the 465 and 4500, input pilot, throw out bearing shaft, 10 spline all the same. Used the HD clutch fork from the 465 bellhousing, drive shaft had to be shortened 4 3/8 in. U-joint is the same size. The end result is a perfect upgrade to an older very serviceable R3500, 1.08 5th gear helps out my 4.56 gear ratio rear to achieve highway speeds while the wicked low 1st gear helps me start out at my loaded GVW of 13,000 lbs. Who knows this may actually get my 10 bolt engine up to 12 mpg (empty). The challenge I have now is for a speedometer, I am still trying to figure out how to convert the electronic speed sensor on my new tranny to the old mechanical spedo in the truck, the least of my worries. Hope this helps someone.