SM465 Questions

[Flashback]

Well I just picked up an 86 C10, its a 305 V8 with what I assume is the SM465 (RPO MM4). I have a few questions about issues it seems to have.

It pops out of 2nd gear often. Usually when I hit a bump or when I give it gas. What would this be a sign of?

Also I seem to have quite a bit of gear noise in first and second gear. I know its not the rearend or carrier bearing, since with the clutch in cruising there is no noise in neutral, but plenty in first and second, none in third. Is this normal for this trans or should I be looking for a replacement?

[Mr Diesel]

Popping out of 2nd probably means the brass syncro gear for 2nd is worn out. This can be replaced without special tools and the gear itself only costs about $15, but it is a lot of work to drop everything and pull it apart.

The gear noise is probably your main shaft and input shaft wearing out. If this is the case you won't notice much noise in 3rd until you get above 55mph or so, depending on rear gear ratio. This isn't too hard to fix but requires special tools and a press, best handled by a reputable shop.

[busman]

are you sure it is a sm465? is it a top loader?

[Irish_Alley]

not saying its not a 465 could of been swapped but from what i remember the 465 is 3/4 tons

[xbanone]

not saying its not a 465 could of been swapped but from what i remember the 465 is 3/4 tons

Almost all manual transmissions from 73-87 were SM465. Poping out of gear is common and fixible as posted above. The other noise you are hearing is probably a bearing in the case. Sounds to me like you should take it to a transmission shop for overhaul. I have one there myself, mainshaft swap, new bearings and all the stuff you have to do to keep it from poping out of gear for $550

[Irish_Alley]

not saying its not a 465 could of been swapped but from what i remember the 465 is 3/4 tons

Almost all manual transmissions from 73-87 were SM465. Poping out of gear is common and fixible as posted above. The other noise you are hearing is probably a bearing in the case. Sounds to me like you should take it to a transmission shop for overhaul. I have one there myself, mainshaft swap, new bearings and all the stuff you have to do to keep it from poping out of gear for $550

lol i guess i dont know anything

[Flashback]

Well so by the sound of things my transmission is going to need a complete overhaul sometime soon. Thats not good news.  At least I got the truck for free. 

On the other hand I can track down a good used NV4500 and install that unit, I know it will require mods to fit properly, but I am up to it.

[VileZambonie]

I hate that trans so I would say go for the swap.

[Irish_Alley]

I'm with vile on this one only having 3 gears kind of sucks. not to mention gas also

[Flashback]

Yea I'm trying to save as much gas as I possibly can with this thing, which is why I also switched out the Holley Double pumper for an Edelbrock unit. The 5 speed will help too, hopefully I can hit 18 - 20 mpg at least.

So my next question is, who has done this swap. Is there a guide out there or am I winging it?

[busman]

well hope you have some $$$ laying around to do the swap. if you want gas mileage why not go with a 700r4 automatic? the nv4500 also has problems with 5th gear popping out under load and you will need the updated lock nut or find one that has already been done.

[busman]

here is some info on the nv4500 from novack-adapt.com they have lots of info for the swap!

Engine Compatibility and Adaptability
The NV4500 is found in GMC & Dodge trucks. The bellhousing pattern for 1993-1994 GM versions is unique from the later (1995-) GM and Dodge units. The 1993 and 1994 Chevy versions have a lower first gear of 6.34:1 and an unsynchronized reverse gear. Transmissions after this period have a higher 5.61 low ratio and reverse gear synchronization.
Input shafts for the GM and Dodge units have 10 splines with 1-1/8" diameter. GM shafts stick out their usual 6-5/8" while the Dodge units are 7-5/8" long.
Summary
Because of its length, moderate gearing, weight and overdrive, the NV4500 is probably best suited for higher powered Jeeps that require a strong transmission with an overdrive gear. If oversize tires are being used, some Jeeps may never see overdrive and lower axle gearing may be in order to compensate for the NV4500's taller low gear. We are often asked about the durability of the NV4500 vs. the SM420, SM465, T18 and NP435 truck four-speeds. We've spoken with GM and Dodge mechanics that have seen some 4500's come through their facilities for repairs for breakage, but this is most often due to too heavy a truck getting in situations it shouldn't be in. For the purpose of Jeeps, the strength issue is nearly irrelevant due to their agile and lightweight nature.
Make: New Venture Gear
Length: 18.9"
Weight: 195 lbs.
Case: Cast Iron
Top Cover: Aluminum
PTO Ports: Both Sides
Gearing: 6.34, 3.44, 1.71, 1, .73, R 6.34 or,
5.61, 3.04, 1.67, 1, .74, R 5.61

also they haave info on the sm465 and parts.

[busman]

some sm 465 info


Earlier SM465
The earlier era of the SM465 include the 1968 - 1978 transmissions. There were both 2wd and 4wd versions. Internally, they are identical to each with the exception of the transmission mainshaft. The 4wd version of this mainshaft (or "output shaft") has a 10-spline output with a 2-5/8" stickout and an accompanying 4wd adapter housing. The 2wd version has a 35-spline threaded mainshaft compatible with a driveshaft yoke, and accompanying 2wd style tailhousing.
Spline Misunderstandings Clarified

"More splines are stronger"

Not necessarily. Larger shaft diameters are stronger, and larger shaft diameters usually require a higher quantity of splines. However, the automotive powertrain industries migrated to more splines on shafts due to their ease (speed, cost, etc.) of manufacture - smaller splines being able to be roll forged instead of the larger splines having to be machine cut.

A 32 spline output shaft vs. a 10 spline spline output shaft is probably only minutely stronger, and a decision of use here should be driven more by compatibility than perceived strength.
Later SM465
The later era of the SM465 include the 1979 - 1991 transmissions. A minor internal change of the 1st gear bushing and thrust washer occurred, in addition to a change from a shorter 10-spline, 4wd output shaft to a 32-spline 4wd output shaft - coinciding with the change of bolt pattern in the New Process 205 transfer case from a figure "8" input bolt pattern to a round, six-bolt input pattern. This pattern was also found on the 208 and 241 chain-driven transfer cases.
Later 2wd style SM465's also incorporated the same 1st gear bushing and thrust washer change, but the 35-spline, yoked output remained identical.
1988-1991 Versions
The last years of SM465 featured a direct-drive (4th gear) switch to signal a lean or cruise mode operation to the GM Engine Control Module (ECM). These final versions had an aluminum top cover and a revised input shaft and input bearing combination. They were found in the C/K Series trucks. Suburbans, however, continued to use the earlier SM465 with the cast iron top cover.

[busman]

http://www.novak-adapt.com/knowledge/sm465.htm

http://www.novak-adapt.com/knowledge/nv4500.htm

[stenny]

I am having trouble with reverse it pops out  especially it you give it gas it wasn't as bad before but it now pops out quicker and easier what could it be?