NV3500 swap

This is how I went about installing a 96/97 S10 NV3500 into my C10, this way worked for me and will probably be a little different if you use an older or newer transmission. I would stick with 96 and up though as they are the strongest versions of them.

Parts list:

Purchased through Rock Auto

Flywheel: LUK LFW101 – 78 C10 5.7
Clutch Kit: LUK 04160 – 98 C1500 5.0
Hydraulic bearing assembly: LUK LSC265 – 98 C1500 5.0

Purchased through Speedway Motors

Rod end-5/16: 1170720
Master Cylinder: Wilwood 70174-750
Banjo bolt kit: 5151398
36” stainless line -3AN: 91031846-3
Adapter-T56 release bearing: 5151396
Remote Bleeder kit-12”: 5151399-12

Ok so to start I put in the clutch pedal box and pedals. I didn’t take many pictures of this, it took a while and you’ll have to remove a good portion of the interior. It helped to loosen the seat and slide it to the passenger side so you can lower the steering column as well. Yes I did use a much cheaper Z-bar (manual linkage) pedal assembly. I cleaned it up, put in new bushings and pedal pads while I was at it.

For a How-to on the bushing replacement and some details on the pedal mounting look here
http://www.gmsquarebody.com/forum/showthread.php?t=6450

Master cylinder mounting

To mount the master I used the hole that speedometer cable passes through the firewall. If you’re using a 96 and up trans the cable is now useless anyway since those trans have a VSS and no provision for a mechanical cable. I plan to us a GPS speedometer app on my phone for now. This is about as high as you can mount it without getting into the area in the cowl for the wiper linkage. It could go up another ¼” maybe but I don’t think that’s necessary and it would be pretty close to the wiper motor then.

I made a template of the back of the master cylinder and lined it up using the existing hole as the lower left side of the mounting hole. I traced out the metal that needed to be removed and cut it out using a dremel tool with a cut off wheel. I attempted to use a hole saw but with no pilot hole it was too hard to control so I just followed my scribed line with the dremel and worked it down until it cut through. I know it looks close and it is but it doesn’t touch the brake booster or the wiper motor and you can easily remove the cap to add fluid.

I then made a plate out of some aluminum I had laying around to help spread out the load on the firewall. I threaded the holes in this plate so that the bolts act more like studs and you don’t necessarily need two people to take the master on and off. To attach the master to the clutch pedal I had to make some modifications to the pedal itself and make an extension to the master cylinder rod. The extension is just a piece of round stock that I drilled and tapped to 5/16-24 on both ends. I took a bolt and cut the head off to attach the extension to the rod end. Now the rod reaches the pedal, but it wants to land in the exact spot the old pedal return spring used to hook to. So I removed the pedal and cut that off flush with the edge of the pedal arm. After another test fit leaving the rest of that pad resulted in the master cylinder push rod being on an angle. This master can take a slight angle but too much will result in premature wear/failure. You also need to make sure the rod is close to level up and down for the same reason. So I cut part of that pad off to give clearance to the rod end. I used two washers to space it out a little and a nylock nut to ensure it stays connected. *in the pictures are 3 washers, I later removed one to lessen the angle on the push rod

I was worried about having a high pedal effort with it mounted about 3.5" down from the pedal pivot point. It was nothing to worry about now as it is no harder to use than a factory manual linkage setup, or anything with a high performance clutch. I’ve driven many other vehicles with a pedal that is much stiffer than this one wound up being. That could be partly from my clutch selection but it turned out good so I’m happy with it.

Hydraulic hookup

During my research I found that the NV3500 uses the same hydraulic bearing assembly as a T56. This helpled me out as I could follow the path that many had used to swap a T56 into older vehicles. This is also why I used the wilwood master since I found much more info about using it in swaps than trying to cobble together two different factory setups (C10 hydro master to newer internal slave).

So on the bearing the factory quick release fitting is held in with a roll pin. Drive that pin out and the factory connection will pull loose from the assembly. You can then install the -3AN adapter the same way, just push it in until it’s seated and reinstall the pin. The pin was a tighter fit with the adapter than the factory one was. The banjo bolt kit is used to convert the master cylinder over to -3AN and simply fits in the end of the master, one sealing washer on each side. The 36” line I used was the perfect length for my truck, if you want to route it differently you’d need a longer one though. The remote bleeder was also nice to have but isn’t necessary. It did make bleeding the clutch much easier and was well worth the extra money to me. The 12” length is enough to reach it easily while under the truck and tie it up to the frame out of the way when you’re done.

Shifter

I found out the hard way here that S10’s and a C/K 1500 don’t use the same shifter. The shifter I got with my trans was a mess. Parts were missing and it was rusty from being left outside. After a lot of searching I found a used one from a 1500. The problem was that they used a different size thread for the shifter handle and the pivot point was higher up on the shifter itself so I couldn’t bolt the shifter to the trans. After some more research I found that Lokar makes a replacement shifter rod for these transmissions (part # MSL610). It shows two locations for the pivot pin and shows in the instructions how to disassemble the stock shifter and what holes to use when replacing the arm. With this info I took my C1500 shifter apart, lowered the pivot ball down and redrilled the hole for the pivot pin. It now works perfect and it fit the shifter arm I had got years ago from a full size truck. I liked it because it was longer and it lands in the perfect spot to reach from the driver’s seat. The S10 shifter arms are much shorter and wouldn’t have been as comfortable to drive with.

To cut the hole in the floor I had the engine and trans in place and measured off one of the factory stamping ribs in the floor to the center of the shifter. I drilled a hole there and double checked that it was in a good location. After that I marked out the cut and I purposely made it smaller than I needed. Once I saw how that went I cut it to size so I was able to remove and install the shifter from inside the truck.

Note—In 98 or 99 the S10 shifter moved farther back on the trans which is similar to all C1500 shifter locations (I believe, they could have changed in the same year range). If you use a newer trans than I did your hole will be located farther back towards the seat.

Trans Cross member and Driveshaft

The transmission cross member did have to be moved back from the factory location. If you are converting from a TH350 it will be quite a ways back from where it was. I converted from a 700R4 and still had to move it back some. I used the same mount on the NV3500 that was on my 700R4 and that mount came off my TH350 when I did that swap.
My driveshaft fit right back in like it did with the 700R4. If you are converting from a TH350 you will have to have the shaft shortened. Check with your preferred driveline shop on how they would like you to measure for the correct driveshaft length.

Clutch Selection

This is where I hit a brick wall. I had read several places that you could use a factory clutch setup for the vehicle the trans was going in with this swap. Well that was bad info for me and my parts setup which caused me a lot more work than necessary. Hopefully I can spare someone else that trouble.

The NV3500 has been around since the late 80s in the GMT400 platform (88-98 trucks). It is called by several different names over that model year run but the early ones used and external slave cylinder that pushed on a clutch fork much like the mechanical linkage setup that would have been factory on a C10. I can only guess that on that style trans you could use a clutch setup for a C10 and it would work perfectly fine. In my case with the internal hydraulic bearing it didn’t work. I had a slightly used 10.5” clutch setup that I had gotten from a friend. It came with everything clutch related that I needed including a 153 tooth flywheel that I bought a brand new starter for. Well I noticed that when I put the trans on the engine it kept springing back when I pushed it up on the dowels and I had to draw it in the last little bit with the bellhousing bolts. I thought that was odd but I also don’t know a ton about clutch setups so I thought it might just be normal because of the pressure plate. Well it wasn’t and once I got the rest of the truck together it wouldn’t move because the clutch was never engaging. It wouldn’t even engage enough to make a burning clutch disc smell. That’s when I found out I needed to use a clutch for late 90s C1500 for proper operation. I don’t think you can use a S10 clutch as they might use a smaller 11” flywheel but I’m not 100% sure on that. In order to avoid buying the wrong parts again I just used a C1500 clutch as the flywheel sizes looked to be the same between it and the one for my C10. The difference in the pressure plate heights was right at a ½” and explains why it would never engage. Once I looked at the pictures of the two pressure plates I could tell the difference and knew I had found my issue.

This is a very good write up with detail thank you. Was this trans behind 4.3 v6 s10 ?

bajatrailrider said:

This is a very good write up with detail thank you. Was this trans behind 4.3 v6 s10 ?

Click to expand...

Thanks! Yes it was behind a 4.3 S10.

Resurrecting this older thread, and sorry to hijack, but I think I read right that you can likley use a mechanical clutch linkage on this transmission instead of the hydraulic clutch, right?

Neat thread, I missed it before.

I had a '91 S10 4.3 with a 5 speed that I always thought was an NV3500. It looked just like the trans in a '91 C1500 that I had worked on a bunch of times (including a clutch job). But over the years I have been told by people that said it wasn't an NV3500. Can you shed some light on that? Also, I think the external slave was gone in '94.

How is the throw on the stick? The C1500 would have had a higher pivot point to make up for the longer stick. So now you have a long stick with the low pivot for the short stick. Does it have dump truck like throws, or is it still a bit more like a stock throw?

Mikeyworks said:

Resurrecting this older thread, and sorry to hijack, but I think I read right that you can likley use a mechanical clutch linkage on this transmission instead of the hydraulic clutch, right?

Click to expand...

No it either has a external slave cylinder or an internal one depending the year of the trans. The part I was referring to when I mentioned that was the clutch disc you could use with the different types of slaves.

bucket said:

Neat thread, I missed it before.

I had a '91 S10 4.3 with a 5 speed that I always thought was an NV3500. It looked just like the trans in a '91 C1500 that I had worked on a bunch of times (including a clutch job). But over the years I have been told by people that said it wasn't an NV3500. Can you shed some light on that? Also, I think the external slave was gone in '94.

How is the throw on the stick? The C1500 would have had a higher pivot point to make up for the longer stick. So now you have a long stick with the low pivot for the short stick. Does it have dump truck like throws, or is it still a bit more like a stock throw?

Click to expand...

It could have been but by a different name. It started out as a HM290 the design was sold an the name changed to 5L60. It was sold again an changed to NV3500. There are some improvements to go along with the name changes but the basic design is the same. One way to tell is the integral bellhousing. According to the Internet S10s started getting them in 1990.

The throw is good imo. I thought about getting a short throw shifter when I had the funds but honestly it's fine as is and I don't see the need to spend the money on it. That might change the more I drive it but for now I'm pretty happy with it as is.

So me and my grandpa bought an 87r-10 i blew it up so we put a 350 in from a 92 that was also a five speed and mated it with the stock 700r4 but now i have convinced my grandpa to let me have the five speed and throw it in. it was a 1992 c1500 stock 5.0 but the guy swapped in a 350 from a 70s c-10. I have the computer from the 92 and everything i think i need to throw it in and am planning on throwing it in saturday and sunday at my bosses shop. Is there any tips i could use to be prepared?

87r-10 said:

So me and my grandpa bought an 87r-10 i blew it up so we put a 350 in from a 92 that was also a five speed and mated it with the stock 700r4 but now i have convinced my grandpa to let me have the five speed and throw it in. it was a 1992 c1500 stock 5.0 but the guy swapped in a 350 from a 70s c-10. I have the computer from the 92 and everything i think i need to throw it in and am planning on throwing it in saturday and sunday at my bosses shop. Is there any tips i could use to be prepared?

Click to expand...

What’s the computer for?
Manual trans needs not a computer.
You will need a way to convert your speedometer to VSS
There are a few methods to choose from here.
But the 92 TBI engine should be swapped over to a carbed intake for you to run

eskimomann209 said:

What’s the computer for?
Manual trans needs not a computer.
You will need a way to convert your speedometer to VSS
There are a few methods to choose from here.
But the 92 TBI engine should be swapped over to a carbed intake for you to run

Click to expand...

The 87 was the first year with tbi so it already has the tbi set up in it and needs a computer to run. The 87 has the 350 with a tbi in it and running already just swapping the 5 speed in. But how would I go about making the speedo work?