Completed auto to NV4500 swap - 86 C20 Suburban - The 1947 - Present Chevrolet & GMC Truck Message Board Network

cal30_sniper · 01-04-2014, 11:24 PM

Hey all,

I've once again tired of driving autos, and decided to jump in and make a manual trans swap on my C20 Suburban. With the heavily cooled 454 up front, and the Richmond No-Slip equipped 14 bolt full floating rear out back, I'd come to the realization that the TH700r4 trans in the middle was by far the weak link (previously swapped the TH400 out for the TH700 in an attempt to boost gas mileage). I looked long and hard at building a TH400/gear vendors combo, but decided with the cost and hassle involved, I might as well go the manual trans route with an NV4500. The fun got accelerated when I decided I was going to do my home of record move for the military as a DITY move. Hauling 8,000lbs of stuff and a dual axle trailer was not something I wanted to try with the 1/2 ton TH700 trans, so I bumped up the swap and got it done in the first week that I got moved down here to Florida. I finished up the move from West Texas to Florida just after new years, and the new trans performed like a champ. The following is a parts list and photo writeup of what all was involved.

Parts List:
-NV4500, out of late 90's Chevy 2500 2wd pickup ($400, Craigslist)
-Advance Adapters Bellhousing Conversion Kit #712576 ($242, Ebay)
-Advance Adapters Slave Cylinder Bracket #715535
-Bolt-in Trans tunnel out of 2wd, auto squarebody ($50, Ebay)
-Hydraulic Clutch pedal out of 85-up squarebody ($100, 73-87 Squarebody Classifieds)
-Hydraulic Clutch Master cylinder and line, I'm currently using one out of a 90's Bronco from the junkyard. I'm still looking for the factory correct parts and bracket if anybody has them.
-Shift boot, I grabbed mine out of a mid-90s chevy truck in the junkyard. It fits perfectly.
-Shortened Driveshaft, 1350 U-joints ($200 Clutch & Powertrain, Pensacola, FL)
-Clutch Master Cylinder AC Delco #38385344 (86 Chevy Truck-Manual Trans)
-Slave Cylinder (NAPA 86 Chevy Truck-Manual Trans)
-Hydraulic Clutch Hose Raybestos BH38559 (86 Chevy Truck-Manual Trans)
-Back Up Lamp Connecter, Standard Motor Products #S712
-Vehicle Speed Sensor Connecter, Standard Motor Products #S553
-4 Qts GL4 Synthetic Manual Trans Fluid, AMSOIL MTGQT
-Chevrolet Performance Flywheel, Summit # NAL 3993827
-Chevrolet Performance Flywheel Bolts, Summit # NAL 12337973
-Centerforce Clutch Cover, Summit # CTF CF165552
-Centerforce Clutch Disk, Summit # CTF 383735
-Centerforce Throwout Bearing, Summit # CTF N1430
-ARP Pressure Plate Bolt Kit, Summit # ARP 130 2201
-Assorted Hardware for bolting in floor hump, mounting clutch slave, etc. I sourced most of that through either Tractor Supply or Home Depot
-Sealant for floor pan, I used Synthetic Black Silicone in caulk gun form from Home Depot

Tools I used:
-Drill with varying bits up to 1/2"
-Cutoff Wheel/Angle Grinder
-Jack, Jack Stands, Transmission Jack (rented for $20)
-3 buddies to help line it up
-Lots of time and patience

The overall swap was pretty straightforward, although at times I got into fairly uncharted territory due to my unique combination of parts. The biggest hurdle to overcome was the lack of any mechanical speedometer options for the Chevy trans. Rather than trying to track down a dodge tailhousing and output shaft with a mechanical speedometer, I decided instead to build a complete VDO gauge panel with an electronic speedometer. That writeup can be found here:
http://67-72chevytrucks.com/vboard/s...d.php?t=610615

Here's the general steps:

1. I tackled the hydraulic clutch pedals first. Unfortunately, when I installed my Vacuum, Wideband Air/Fuel, Trans Temp, and Tach gauges on top of the dash, I identified the same clutterfree location on the firewall to install my gauge grommet that GM saw fit for putting a clutch master cylinder through. Even more unfortunately, the hole I drilled was close enough to overlap, but not close enough to overlap. As it was, the hole I had already drilled swallowed about half the master cylinder hole, including one of the bolts.

I got around this problem by building a sheet metal plate that would cover the entire area. I used the master cylinder as a template to measure exactly where the holes needed to be, and then drilled them out. By bolting the template to the firewall without the master cylinder attached, and then drilling the center hole through the template and firewall at the same time, I was able to get the hole centered and clean even though it overlapped the old hole in the firewall. The photo below shows the finished cut. Note the empty hole where the mechanical speedometer cable ran through the firewall. That is where I eventually moved the extra gauge wiring to:

The photo below shows the custom sheetmetal piece I made. I painted it and mounted it between the pedal assembly and the firewall as extra reinforcement against them pushing through. The photo below shows the finished product from inside the cab:

Note that I did remove the through bulkhead connector and wiring harness to perform this work. I highly recommend doing so to avoid damaging it during the cutting process.

The rest of the pedals are a very straightforward process. Simply unbolt the automatic pedals, transfer over the cruise and brake light switches, and bolt in the manual pedals. My pedals lacked the two copper washers and cotter pin for the attachment of the master cylinder to the clutch pedal. Never fear, GM was smart and used the same parts for both the brake and clutch pedal attachment. I ran to the junkyard and sourced the extra washers and pin from the brake pedal on a 90 Suburban auto.

2. The floor hump. A very involved process to get measured and cut correctly. The bolt in hump that I purchased didn't wind up fitting very closely to the floor pan. It ended up taking a lot of bolts and some BFH work before I got all the gaps closed up around the pan. To cut the floor, I laid down the bolt in hump and traced the outline in sharpie on the floorpan. I then removed the hump and drew a second outline 2" inboard of the first. At that point, I used a cutoff wheel to cut out the inside outline. After I was satisfied with the dimensions, I used the angle grinder to smoot the corners and get rid of any nastiness. Finally, I used a metal file to remove the burrs and get a nice smooth finished product.

The photo below shows the marked floorpan:

Initial Cut:

Fitment of pan before any massaging:

After beating on top of the pan with the hammer for a while, I had it fitting fairly closely to the floor. By putting pressure down on the pan (sitting on it), and drilling the holes out for the bolts, I was able to get the bolts themselves to pull the pan down to the floor. Satisfied with the fitment, I pulled the hump out, built a plate to cover the hole where the transfer case lever used to go through, and set the pan aside to await cutting of the shift hole pending installation of the trans.

3. Flywheel, Clutch, and Bellhousing. Here's where things started to get a little weird. The flywheel and clutch assembly went on without a hitch as did the pilot bushing (included in AA kit), and I was able to line up the clutch very easily with the Centerforce #53010 alignment tool. The first mockup of the bellhousing showed excellent clearance all the way around, including my high-torque ministarter sourced from a '98 C2500 7.4L Suburban. Here's a photo of the installed clutch:

And the bellhousing assembly, with slave cylinder and bracket attached. At this point I went ahead and installed all of the clutch hydraulic hardware too:

Master cylinder installed:

Speedometer Cable Bracket reused to hold hydraulic clutch line:

At this point I realized that installing the clutch fork was going to be tricky. The supplied pivot ball and spring for the clutch fork were extremely tight, and very difficult to assemble. At first, I thought that I might have gotten the wrong combination of parts from my ebay auction. I ended up having to lay the clutch fork down on the ground, ball pivot side facing up. I placed the pivot ball in its socket, and hooked one side of the spring in its groove. I then had to use a pair of needlenose pliers and a flatblade screwdrives to force the other side of the spring into its groove. After determining it would fit, I took it back apart and applied a liberal dose of white lithium grease to the stud. I was now able to screw the clutch fork pivot stud to the bellhousing, and install the bellhousing onto the truck.

Here, another dilemma occurred. With the clutch fork already hooked up, and no way of removing it or sliding it out of the way, I had to figure out a way of holding the throwout bearing, centered in its location, while the rest of the transmission was installed. After some pondering, I came up with the easy solution. I simply removed the input shaft and bearing, bearing retainer and race, and custom advance adapters throwout bearing adapter, and used the input shaft to align them with the clutch assembly, passing the entire setup through the clutch fork and throwout bearing as I slid it in the transmission. I was then able to back out the adjusting nuts on the slave cylinder until the clutch fork and throwout bearing began to compress the fingers on the clutch cover. This provided enough pressure to securely hold the throwout bearing centered in place, and I was able to slide the input shaft assembly back out and reinstall it in the transmission.

With the bellhousing now installed, I decided to go ahead and fab an inspection cover plate for it while I waited for my buddies to get home and help wrestle in the transmission. I used a piece of flat sheet metal from home depot. First, I used the old TH700 inspection plate cover to trace the cutout lines for the upper portion of the plate. After that was complete, I slid the plate in and used the outline of the bellhousing to trace the outer cut marks. Satisfied with the fitment, I drilled holes, painted, and installed.

Plate, prior to drilling:

Plate, installed:

4. Then the fun part. The actual installation of the transmission was not very difficult at all. I removed the shifter housing from the top of the trans so that I could slide the transmission and jack under the vehicle as a unit rather than trying to wrestle it on to the jack under the truck. The trans itself slid right in with very little effort, and I was able to get it all the way forward into the pilot bushing and flush with the bellhousing prior to installing the four large transmission to bellhousing bolts.

A photo of the trans in place:

5. My next move was to get the crossmember in. The fit was very close, but some grinding of the forward edge of the crossmember was required to clear the much larger case of the NV4500. Here's a picture of the ground area. Please note that I only took out a portion of the lower horizontal surface of the crossmember. I did not touch the vertical face, as any removal of this area would weaken the overall strength of the crossmember.

Once the clearance cut was made, about half of the holes in the crossmember lined up with holes already drilled in the frame. I drilled the remaining holes with a 1/2" drill bit, using the holes in the crossmember as a guide. I also drilled two extra holes in the bottom on the drivers side to provide more of a vertical force against the much heavier weight of the NV4500. I installed it with all new flanged grade 8 bolts from Tractor Supply.

6. At this point I bled and adjusted the clutch hydraulics, and prepared to finish modification of the trans tunnel. I used a straightedge and a tape measure to mark the location of the shifter relative to the holes I had drilled in the floor pan. I transferred this mark to the trans hump, and then marked out and cut a hole with the cutoff wheel just large enough for the shift tower to stick through the tunnel, shown below:

With the hump resting in place, I reinstalled the shifter and shift boot, using the boot as a template to mark an outline on the trans tunnel.

After removing the shifter and tunnel again, I drew an inner outline for the inside edge of the boot, and cut that shape out with the cutoff wheel/angle grinder and metal file. After the cut was complete, and holes to attach the shift boot had been drilled, I sealed up the transfer case cover plate with silicone and painted everything. The photos below show the finished floor hump prior to and after sealing and painting.

The rest was just putting everything together up and driving. I reused the factory carpet and insulation, being very careful to cut the hole for the shifter in the correct location. Due to the larger size of the trans tunnel, the carpet now has about an inch gap on either side where it meets the kick panel. However, the aluminum door sill plates more than cover the gap everywhere else. The shift location with the factory handle is perfect, and does not interfere in any way with the dash or center console.

I now have about 2500 miles on the swap. I have yet to get any unloaded MPG numbers for comparison, but I can verify a significant increase in mileage while towing. I had a total combined weight of 13,800 lbs, including a dual axle car transport with my BMW on top, when I moved from VA to FL with the TH700 just prior to beginning the swap. At 65-70 mph, I averaged 8.5 mpg. With slightly more load (same interior load, only my '88 GTA on the trailer instead of the BMW), I averaged 10.7mpg at 65-70 mph when I moved from TX to FL with the NV4500 installed. Shifts are amazingly smooth, the clutch is awesome, and the big 454 provides all the right torque in all the right places to make for some really, really fun driving, even when just cruising around.

Did I mention that the granny low makes for some really awesome offroading with that 3.73 locker in the back? This thing is awesome going up and down grades.

Overall, I highly recommend the swap. Make sure you start off with the right tools for the job, and go ahead and give yourself a few more days than you would think necessary. I ended up doing the swap in a week, but some of those days were very hurried, 20+ hour days trying to make my deadline for arriving in TX. Other than that, I couldn't be happier.

-cal30sniper

P.S., if anybody has the bracket to hold the hydraulic reservoir to the firewall, I could really use one. I'm also still looking for the switch and mounting tab for the cruise control disconnect that goes on the clutch pedal. The pedals I got were from a non-cruise truck and don't have the bracket attached. I'll post a write-up on my solution for the cruise control/VSS interface when I've completed it.

**Captainfab** · 01-05-2014, 01:43 AM

Thanks for posting this great write up

This will come in handy even for those of us performing the swap in other than a squarebody.

I have one question, did this trans originally have the hydraulic throwout bearing?

cal30_sniper · 01-05-2014, 02:42 AM

Thanks! I hope it helps someone else avoid some of the confusion and headaches that I had with this. Should be pretty much universal other than the clutch hydraulics which will vary by vehicle.

Trans was originally an internal slave transmission, with the slave and throwout bearing being one unit attached to the input shaft bearing retainer. I ditched that and the original bellhousing to go with the Advance Adapters unit. The throwout bearing guide in the AA kit bolts to the same location the old internal slave did. They use a mechanical linkage style clutch fork and use a threaded stud to attach that to the hydraulic slave cylinder. I should have taken some better pictures of that part of the process, but I was working to hard at that point to stop and take pics.

-cal30sniper

**Captainfab** · 01-06-2014, 01:27 AM

That answers the question I had about whether a standard TO bearing would fit in place of the hydraulic throwout bearing. It sounds like the input shaft bearing retainer needs to be changed.

Quote:

Originally Posted by cal30_sniper

Thanks! I hope it helps someone else avoid some of the confusion and headaches that I had with this. Should be pretty much universal other than the clutch hydraulics which will vary by vehicle.

Trans was originally an internal slave transmission, with the slave and throwout bearing being one unit attached to the input shaft bearing retainer. I ditched that and the original bellhousing to go with the Advance Adapters unit. The throwout bearing guide in the AA kit bolts to the same location the old internal slave did. They use a mechanical linkage style clutch fork and use a threaded stud to attach that to the hydraulic slave cylinder. I should have taken some better pictures of that part of the process, but I was working to hard at that point to stop and take pics.

-cal30sniper

cal30_sniper · 01-07-2014, 11:36 AM

You keep the factory GM bearing retainer, just remove the internal hydraulic slave cylinder from the front. Once it's out of the way, you'll see two smaller threaded bolt holes in the face of the bearing retainer. Advance Adapter's throwout bearing adapter fits over the front of the bearing retainer and uses these two bolts to attach. You can see a good picture of the setup on page 3 of this pdf: http://www.advanceadapters.com/downloads/712576.pdf

Page 2 also has a schematic drawing of the throwout bearing adapter itself. Apparently you also have to order the special Centerforce throwout bearing they recommend for this as well. Not sure why, but I went ahead and ordered it as I didn't have time to fool around with other stuff.

-cal30sniper

burnin oil · 01-07-2014, 01:13 PM

I bet that you could make it work with a standard bearing also. The Dodge light duty version, ie v8 gas motor, had the same input diameter as the chevy. It was longer but also lets you use the AA bellhousing adapter. I bet the bearing retainer would fit the bill. That is the route that I am going on my trans when I swap it in.

Average Joe · 01-08-2014, 09:11 PM

Awesome write up. Thanks for taking the time and effort to do this and the guage install. Mods: this deserves to be in F.A.Q.

**Captainfab** · 01-09-2014, 12:15 AM

Thanks for the clarification on the bearing retainer.

Edahall · 01-09-2014, 02:37 AM

Welcome to the Manual Transmission Suburban Club!

earl84 · 01-09-2014, 11:53 AM

This writeup is awesome, thanks for taking the time to do it. May or may not do this swap at a future date, but if I do, I now have an amazing resource saved.

cal30_sniper · 01-09-2014, 12:11 PM

Quote:

Originally Posted by Edahall

Welcome to the Manual Transmission Suburban Club!

Don't know why I waited so long to get there!

Viperject · 01-09-2015, 06:35 PM

Any updates on this truck? Any problems/failures resulting from the swap and its assortment of parts?

I would like to put an NV4500 behind a 6.2L diesel in a 3/4-ton 2WD Suburban and this write-up will be extremely helpful. I don't know enough about transmissions to attempt a rebuild myself and I don't trust the used parts I find on craigslist/eBay, so I'm considering one of these:

http://nv4500transmission.com/

These guys apparently do some custom building specific to your intended application, so that may help.

Quote:

Originally Posted by cal30_sniper

-Bolt-in Trans tunnel out of 2wd, auto squarebody ($50, Ebay)

I assume you mean the tunnel from a 4WD auto squarebody, correct?

I think I have seen NV4500 conversions that did not involve the use of a larger/taller trans tunnel. I assume, then, that a body lift was used instead. How much of a lift do you think would be necessary if that route is taken?

Did you retain the auto-shift steering column and indicators? When I perform the swap, I intend to purchase a 4-speed C20 donor truck. There always seems to be at least one local, non-running example available for $1000 or less, often equipped with the 6.2L. It may cost more initially to start with an entire donor vehicle rather than assemble the individual parts, but I think it would make the entire process much easier/faster (plus I may be able to sell the leftovers post-conversion).

cal30_sniper · 06-03-2015, 11:26 PM

Yes, it was an auto, 4WD truck tunnel, sorry for the confusion. You will need a higher tunnel, no way around it. You don't need a body lift, and I wouldn't recommend one. Too much extra work to make it come out right, and your whole truck becomes less aerodynamic and less stable with no extra ground clearance. Just get a 4WD tunnel, it gives plenty of clearance all the way around.

The truck is still going strong 17k miles later. I've had it over the hill and up the dale. I towed a 13k lb load from Florida to South Texas, and have hauled my two Firebirds all over creation on a dual axle car trailer. First gear has worked out great with the locker in the rear for offroading out in the desert. Haven't found a place yet that I wasn't able to get in and out of.

I retained the auto steering column. I couldn't find a tilt manual column in good shape. I removed the shifter, the linkage, and the indicator in the instrument cluster. I used the instrument cluster to mount lights for the Emergency Brake and High Beams.

Farm Shop · 12-04-2015, 09:31 AM

Great write-up, Sniper, but your pictures aren't showing up for me. Any chance you could re-link them?

Also, why did you choose to change from the internal slave, to the external/fork style with the AA kit?

Theboatandcarman · 09-28-2016, 09:56 PM

Quote:

Originally Posted by Farm Shop

Great write-up, Sniper, but your pictures aren't showing up for me. Any chance you could re-link them?

Also, why did you choose to change from the internal slave, to the external/fork style with the AA kit?

yea unfortunately photos are down

**LockDoc** · 02-01-2017, 12:16 AM

-
Here is one I posted when I put the Chevy NV4500 in my '72 Dually, behind a crate 350. I don't know if there is any difference in the later NV4500's or not. No adapter to buy with this method. Just make sure the bolt pattern on your trans is the same as what I used and the hole in the bell housing is the correct size for the front bearing retainer on the trans.....

http://67-72chevytrucks.com/vboard/s...d.php?t=673588

LockDoc

cal30_sniper · 06-27-2017, 08:37 AM

The quote below has been updated to show the pictures from the original thread that got deleted. If a moderator wants to copy this post into the original, it will have the pictures up top again. I can't figure out how to edit the original, I think it may be too old.

Quote:

Originally Posted by cal30_sniper

Hey all,

I've once again tired of driving autos, and decided to jump in and make a manual trans swap on my C20 Suburban. With the heavily cooled 454 up front, and the Richmond No-Slip equipped 14 bolt full floating rear out back, I'd come to the realization that the TH700r4 trans in the middle was by far the weak link (previously swapped the TH400 out for the TH700 in an attempt to boost gas mileage). I looked long and hard at building a TH400/gear vendors combo, but decided with the cost and hassle involved, I might as well go the manual trans route with an NV4500. The fun got accelerated when I decided I was going to do my home of record move for the military as a DITY move. Hauling 8,000lbs of stuff and a dual axle trailer was not something I wanted to try with the 1/2 ton TH700 trans, so I bumped up the swap and got it done in the first week that I got moved down here to Florida. I finished up the move from West Texas to Florida just after new years, and the new trans performed like a champ. The following is a parts list and photo writeup of what all was involved.

Parts List:
-NV4500, out of late 90's Chevy 2500 2wd pickup ($400, Craigslist)
-Advance Adapters Bellhousing Conversion Kit #712576 ($242, Ebay)
-Advance Adapters Slave Cylinder Bracket #715535
-Bolt-in Trans tunnel out of 2wd, auto squarebody ($50, Ebay)
-Hydraulic Clutch pedal out of 85-up squarebody ($100, 73-87 Squarebody Classifieds)
-Hydraulic Clutch Master cylinder and line, I'm currently using one out of a 90's Bronco from the junkyard. I'm still looking for the factory correct parts and bracket if anybody has them.
-Shift boot, I grabbed mine out of a mid-90s chevy truck in the junkyard. It fits perfectly.
-Shortened Driveshaft, 1350 U-joints ($200 Clutch & Powertrain, Pensacola, FL)
-Clutch Master Cylinder AC Delco #38385344 (86 Chevy Truck-Manual Trans)
-Slave Cylinder (NAPA 86 Chevy Truck-Manual Trans)
-Hydraulic Clutch Hose Raybestos BH38559 (86 Chevy Truck-Manual Trans)
-Back Up Lamp Connecter, Standard Motor Products #S712
-Vehicle Speed Sensor Connecter, Standard Motor Products #S553
-4 Qts GL4 Synthetic Manual Trans Fluid, AMSOIL MTGQT
-Chevrolet Performance Flywheel, Summit # NAL 3993827
-Chevrolet Performance Flywheel Bolts, Summit # NAL 12337973
-Centerforce Clutch Cover, Summit # CTF CF165552
-Centerforce Clutch Disk, Summit # CTF 383735
-Centerforce Throwout Bearing, Summit # CTF N1430
-ARP Pressure Plate Bolt Kit, Summit # ARP 130 2201
-Assorted Hardware for bolting in floor hump, mounting clutch slave, etc. I sourced most of that through either Tractor Supply or Home Depot
-Sealant for floor pan, I used Synthetic Black Silicone in caulk gun form from Home Depot

Tools I used:
-Drill with varying bits up to 1/2"
-Cutoff Wheel/Angle Grinder
-Jack, Jack Stands, Transmission Jack (rented for $20)
-3 buddies to help line it up
-Lots of time and patience

The overall swap was pretty straightforward, although at times I got into fairly uncharted territory due to my unique combination of parts. The biggest hurdle to overcome was the lack of any mechanical speedometer options for the Chevy trans. Rather than trying to track down a dodge tailhousing and output shaft with a mechanical speedometer, I decided instead to build a complete VDO gauge panel with an electronic speedometer. That writeup can be found here:
http://67-72chevytrucks.com/vboard/s...d.php?t=610615

Here's the general steps:

1. I tackled the hydraulic clutch pedals first. Unfortunately, when I installed my Vacuum, Wideband Air/Fuel, Trans Temp, and Tach gauges on top of the dash, I identified the same clutterfree location on the firewall to install my gauge grommet that GM saw fit for putting a clutch master cylinder through. Even more unfortunately, the hole I drilled was close enough to overlap, but not close enough to overlap exactly. As it was, the hole I had already drilled swallowed about half the master cylinder hole, including one of the bolts.

I got around this problem by building a sheet metal plate that would cover the entire area. I used the master cylinder as a template to measure exactly where the holes needed to be, and then drilled them out. By bolting the template to the firewall without the master cylinder attached, and then drilling the center hole through the template and firewall at the same time, I was able to get the hole centered and clean even though it overlapped the old hole in the firewall. The photo below shows the finished cut. Note the empty hole where the mechanical speedometer cable ran through the firewall. That is where I eventually moved the extra gauge wiring to: