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Discussion Starter · #1 ·
So my NV3500 manual transmission had been making a whining noise for 5-6 years in all gears except 4th. At one point in its early life, I believe the rear tailshaft seal had been leaking which led to low fluid and the eventual whine.
About a month ago, it started making a new noise: a very loud "clunk" that ran about 1/50th of the engine speed. So it was a very slow slunk but very loud. Rather than leaving me stranded. or worse, have it lock up while going 60 mph down the highway, I decided to tear it down.

I'll post pics for the benefit of others, or for those who are just curious :)
 

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Discussion Starter · #2 ·
This is the very very dirty transmission from my S10, waiting for me to separate the bell housing (left) from the main transmission (right).

The only gotchas for me where not knowing that there were TWO dowels, one on each side of the main tranny body, that have an interference fit. So just unbolting the two halves won't necessarily free them to be pulled apart. A little careful prying at strategic strong points was needed to separate it.

 

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Discussion Starter · #4 ·
The transmission has a mainshaft, which has all of the "speed" gears, and a countershaft, which has gears but is one solid piece.



I have a nice broken tooth on the first gear (which is not 1st gear) of my countershaft:



And the input shaft to the tranny, which mates with that broken gear on the countershaft, also has some broken teeth:

 

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Discussion Starter · #6 ·
"Only" 32 special (and overly expensive) tools are supposedly needed to disassemble and then reassemble this mess. So far, I have only had to buy one: lock ring pliers. They have duck bill ends instead of pointed ends found on snap ring pliers.

The transmission has many lock rings, and after spending more time than I care to admit removing just two, I broke down and bought these pliers.

1. Wilde G705B Compound Leverage Lock Ring Pliers
The jaws on these stay parallel when opened, so they don't slip off!
http://store.harryepstein.com/cp/MiscPliers/G705B.html

2. Wilde G704P.B 9" Straight Tip Lock Ring Plier
http://store.harryepstein.com/cp/MiscPliers/G704P.B.html

I'm glad I bought both sets because there were certain lock rings that were easier to remove with the G704P.B, but most required the G705B compound pliers.
 

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Discussion Starter · #7 ·
Cool detailed rebuild with great pictures!

I have the same transmission- hopefully mine wont need this attention anytime soon.
Thanks! I took a lot of pictures so I'll try and share what's appropriate.

The NV3500 seems well built to me. I imagine that as long as you have the correct amount and type of fluid at all times, you hopefully won't ever have to do this!
 

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Discussion Starter · #8 ·
Transmission Input shaft. It sticks out the front of the transmission, and those splines slide into the clutch assembly. Unhappy gears at the bottom.

Those unhappy gears drive the countershaft. The larger diameter teeth at the bottom are what the synchronization slider mates with to lock in "4th" gear (which really isn't a gear at all).



As it turns out, that single groove in the splines about 1/4" down from the top is very important when picking out a replacement shaft! More about that later.
 

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4 Year Intermediate Tech
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I plan on doing a rebuild on mine soon, I may pm you for details. Very cool. Mine has 277,000 miles on it.
 

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Real Man
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How much would you figure your rebuild cost you, tools and all? I want to rebuild mine myself but can get one with 135K on it out a full size 1/2 ton for $600. Just weighing my options as my budget on my 350 swap is extremely tight.

My current trans has 227K miles on it. Only problem is will grind going into 3rd and will pop out of 1st sometimes if you let the clutch out too fast (ie. dumping it :D)
 

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Discussion Starter · #12 ·
I'm reassembling it now and don't foresee the need for any more parts, so here's what I have in it so far. Note that the internal parts needing to be replaced in your rebuild will likely be different (and less) than mine, but at least plan on the rebuild kit, fluids, and tools:

New input shaft: $97
Used Main Gear and Cluster Gear Set: $120
Misc. bearings/bushings (u probably won't need): $54.03
Tailshaft bushing: $8.64
Needle bearing kit: $28.77
Fully Rebuild Kit w/ Synchros: $218
3-4 Shift Fork (mine had damage from overheating): $43.00
Wheel Speed Sensor Gear: $10.24
Speed Sensor:: $28.84
Backup switch: $12
Dr. Tranny Green Assembly Goo: $10.68
3 quarts ACDelco 10-4006 Synchromesh Fluid: $38
Compound and Normal Lock Ring Pliers: $43

Total: $712
All prices include what I paid for shipping.

I'm also replacing the clutch and related components.
 

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Real Man
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That sounds reasonable. Where is a good place for a rebuild kit and other associated parts? I think mine just has bad synchros in it. Probably won't need all the gears. Mainly, I want to replace the synchros, seals, bushings, and bearings. Thanks.
 

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Discussion Starter · #14 ·
I can highly recommend Cobra Transmission for the rebuild kit. I also got my new input shaft and clutch pivot ball stud from them. There's a lady that answers the phone that is very helpful.

DO NOT do not order from American Powertrain Warehouse! They claim to ship same day but did not. It took almost two weeks. I tried contacting them three times by email, twice by phone ("the Magic Jack customer is not available..."), and once using their web "contact" page. I had zero contact back from them. I had to file a PayPal claim which I did close when the parts finally arrived. Also, they gave me no shipping info or tracking numbers.
 

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Discussion Starter · #15 ·
New and used transmission parts ready for assembly. Genuine GM Synchromesh fluid, and a toothbrush just in case.

 

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Discussion Starter · #20 ·
1st/2nd gear synchro installed. This is one of several operations that supposedly requires a Press, but by evenly and gently tapping the synchro assembly simultaneously on opposite sides with hammers, it goes on just fine.

I don't know what the synchro slider rings are made of, but they are tough as titanium; I was unable to even mark the surface with a scribe.

 
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