1994 Diesel Suburban Build

[aardvarcus]

19bonestock88,
It doesn’t drag that bad, it actually has a decent amount of clearance, more than the pictures make it look like. Also it is designed to drag/deflect and pop right back. I ran a very similar design on my Tacoma for three years, including offroad use, without any issue. Drag seemed to go down just a touch with it on, handling was significantly improved though. This iteration follows the shape of the stock bumper, which is a limitation.

Funkhoss,
I think I have found a rebuilder that will work with me as far as the early gears in the late transmission, still have to iron out some details to order that though. I have a 14B SF from my k2500LD, but for this project I think I will stay with the 14B FF and regear it at the 3.42 ratio. That is interesting about the 2.93 gearset being offered for the 9.25, I never knew that and thought 3.42 was the limit for those as well. I know there is talk on forums about the crosswalk of lockers between the 9.25 IFS and the 14B SF. With 235/85R16 tires, the revised NV4500 overdrive, and 3.42 gears I show 1592 RPM at 55 and 2026 RPM at 70.

[aardvarcus]

Trimmed the air dam back a touch. I am afraid it is not fully deflecting the air around the tires, but it will have to do until I replace the front bumper. I removed the roof rack, caulked the holes, and painted the roof white. That should help keep the cab of the vehicle cooler. Noted a minor change in drag with the roof rack gone, based on hill coasting speeds.

The MPG has been between 22 and 23 the past few fill ups with the new tires. I have been too excited to check MPG to run it to a full tank, which would take me over 900 miles, so I have been filling it between 100 and 200.

I have ordered a new steering gear, the stock one has deflection in the output which translates into steering slop. From a drive-ability standpoint I still need to swap out the drivers seat and fix the cruise control.

[deejaaa]

what did you paint the roof with?

[aardvarcus]

Deejaaa,
I used three coats of Gloss White Rustoleum Professional spray paint, over a coat of the similar Red Primer. In addition to wanting the roof white I was also trying to keep the corrosion from forming more until I have a chance to repaint the entire vehicle properly. At that point I will probably paint everything from the windows up white, similar to how some of the older trucks were.

Everyone,
My last tank rendered 23.5MPG, so it is moving in the right direction. The front end of the truck has been sitting rather high, I never cranked up the torsion bars but all the weight loss I did on the front end inevitably caused the front end to rise up. Last night I decranked the torsion bars back down until the CVs were flat. I could tell an immediate improvement in ride quality.
The jury is still out on a MPG improvement from the front lowering, I noted my hill coasting velocities seemed to dip a bit this morning. May be a fluke, but if it is true I will have to adjust elsewhere or crank them partially back up. I am guessing that because the Suburban is now at more of an angle it effectively lowers the front air dam in addition to canceling some of the micro-boat tailing GM did at the end of the roof.

[funkhoss]

Originally Posted by aardvarcus

With 235/85R16 tires, the revised NV4500 overdrive, and 3.42 gears I show 1592 RPM at 55 and 2026 RPM at 70.

Actually, your RPMS should be a bit lower than that. With 31.7" tires, 3.42 final drive, and 0.643 overdrive, you should be seeing 1282 at 55 and 1632 at 70. Not bad at all.

The RPMS you gave are about what my wagon will do with the revised overdrive, 30.5" tires, and a 4.10 rear.

-Funkhoss

[aardvarcus]

Funkhoss,

Thank you, you pointed out a glaring issue that I should have known about. My engine reads RPMs off the alternator, which has been switched out and probably has the wrong pulley size. All the RPM numbers I have given up until know are based from the instrument cluster reading, which I now calculate is 20% too high. Reverse engineering off Michelin’s 656 rotations/mile, 4.10 gears, and 0.726 overdrive I am sitting at 1791 RPM @ 55 and 2280 RPM @ 70, so much better than I thought. I also just did the gear tooth counts and confirm the early overdrive is .726, the late overdrive is 0.745 and the potential early/late hybrid overdrive is 0.643. I now show for the hybrid transmission 1635/2080 at 55/70 respectively, and down to 1208/1537 with 3.42 gears so much closer to what you had calculated than my previous estimation. So thanks again.

Everyone,

My prior tank was down a bit but my last tank was a new record at 24.4 MPG. I have also noticed much variability with my hill coasting speeds, must be wind or other factors, so I won’t rely on that anymore. I have some service work I need to do to replace a few items, I need to get that taken care of soon. I am in the middle of a garage cleaning/reorganization project right now, I need to get that completed so I can get the patient back into the operating room.

[aardvarcus]

Everyone,
My MPGs over the last few tanks have been consistently 24+, so the front end lowering has indeed helped.

Finally got the Suburban back into the garage last night, had to replace some cracked exhaust biscuits. Had to deal with crappy mis-tapped hardware trying to cross thread the whole time until I gave up and found some other nuts, so that took longer than it needed to.

I have ordered a new late NV4500 transmission and a reproduction early 5th gear set. I am planning on trying to assemble the hybrid overdrive transmission, so wish me luck. I also had to get other clutch/bellhousing parts as the late style won't work with my early external slave cylinder parts.

[aardvarcus]

New old stock, straight out of 1998. I have collected quite a few parts to bolt onto Deep Blue, I will probably have a focused weekend soon to just work on it.

[funkhoss]

Were you able to get the gears into the NV4500 and the NV4500 into the Suburban?

The pilot bearing in my wagon bit the dust a few weeks ago, so I went ahead and swapped the NV4500 in while I had the NV3500 out.

As part of that process, I put an aftermarket "early" fifth gear set into my "late" NV4500 before I installed it. So, if you haven't done that gear swap yet, I can now officially confirm that it works.

I've driven it with the 0.643 NV4500 a few times now and it seems to work great. I guess I need to update the thread on my wagon eventually...

-Funkhoss

[aardvarcus]

Funkhoss,
I had to take a bit of a hiatus from the Suburban project due to other priorities, so while I have all the parts in my garage I haven’t actually swapped them over yet. Glad to hear an official confirmation though, that is reassuring. Since I paused the project I have been driving the Suburban occasionally and instead have been daily driving the Tacoma. I hope to get the transmission and other parts swapped over on the Suburban soon, so it can go back to daily status.