The Story Of A Cummins Suburban (Lots Of Pics)

[HemiChallenger71]

But you've added and intercooler and better flowing turbo now so your safe egt is actually a bit higher. If its not blowing black smoke your fine to take it to 1200-1300. The 14cm housing helps too.

Turning the full power screw up will add fuel at higher rpm/wot. Currently the wastegate is not used, if it was allowed to open you will lower backpressure and increase exhaust flow IF theres enough exhaust flow to open it and keep it open in the first place. Dont be afraid of boost either. 35-38 psi is pretty common for factory turbos and factory parts.

I run my ppump up to 1400 1500 regularly, but only for short jaunts, not sustained. The newer trucks will hit 1300+ all day long in factory form.

[mosesburb]

Originally Posted by HemiChallenger71

But you've added and intercooler and better flowing turbo now so your safe egt is actually a bit higher. If its not blowing black smoke your fine to take it to 1200-1300. The 14cm housing helps too.

Turning the full power screw up will add fuel at higher rpm/wot. Currently the wastegate is not used, if it was allowed to open you will lower backpressure and increase exhaust flow IF theres enough exhaust flow to open it and keep it open in the first place. Dont be afraid of boost either. 35-38 psi is pretty common for factory turbos and factory parts.

I run my ppump up to 1400 1500 regularly, but only for short jaunts, not sustained. The newer trucks will hit 1300+ all day long in factory form.

The wastegate was dumping at something like 14ish psi. By clamping it off it spins up to 25ish now. As I understand it, the early non-I/C motors got the lower EGT limits because of either the piston design and/or coatings (or lack thereof) or the cylinder head casting itself because of the larger injector nozzles the non-I/C motors got. I know even the first p-pump motors had a higher allowed EGT limit right off the bat. It has been a long time since my research to remember why it was. Either way, the motor runs under the 1150* mark now pulling hills, so all seems well with that.

[mosesburb]

So as some of you know I have been less than thrilled with the performance and tread life of the E rated BFG All Terrains that I have had on this for a little over 20K miles. I was at the tire shop recently getting a slow leak fixed and noticed how low on tread they were getting and then the guy brought up the purchase info on his computer and I saw how much I paid for them and how recently I paid it. That brought my opinion of the tires to a new low. Now I realize I use the tires a bit harder than the vast majority of BFG AT owners do, but to whack that much tread from the tires in that amount of time was ridiculous. I maintain pressure regularly. It always gets checked before a trip as well as when we air up after a trail. I have leaks fixed as soon as I notice them. I have the tires rebalanced annually or so. So even with all of the trail miles I put on these, they lead a fairly pampered life. If this tread life is indicative of high maintenance, I'm far from impressed. Now mind you they were not worn out, but when no tire guy in his right mind would come to where we travel to fix a tire, I tend to err on the side of caution when it comes to tires. If it was a street queen I would not have been as nervous, but they were getting a bit thin for trail use.

What to do?? What brand to go with?? This guy says Toyos are great and that guy says Toyos are wet crap. That guy says Nittos are great. This guy says Nittos are only good for wheeled garbage cans. Ugh. Who to believe?? I solicited opinions from several people I know, many who use their vehicles is a variety of conditions, from street to trail to industrial. I got a wide range of opinions just like the examples shown earlier. These work for this guy and that guy had no luck with the same tire. Ugh. I started doing my own research with no idea where it was going to lead (other than AWAY from BFG). I had heard some good things about Toyos, so I was checking those out. I was reading reviews of the different aspects of performance of the different tires. The MTs were sounding like a good tire, but I really don't need (or want) a mud tire. The reviews of the ATs were not as good for what I was doing, but still looked like a good tire. The AT IIs were a nice tire as well. One thing I noticed on our trip last year through UT, MT, WY, SD, CO, etc, was how many one ton service trucks had Toyo M55s on them. You'd swear they came from the factory on those trucks up there. I started looking in into those tires. They are a full-on commercial tire suited for pretty brutal conditions like logging, oil/gas fields, mining etc. After reading the reviews on as many sites as I could find info on I was becoming more and more sold on them as I read more reviews on them.

The tread pattern falls between a mud lug and an all terrain pattern. It has good tread voids. The reviews tout great performance in pretty much all weather/road conditions including ice which is not normally a strong point of a lug type tread with a lot of negative space. Well, it looks like I found my tires. Now to go buy a set. Yeah, I'll just go buy a set. Not quite that easy. I went to a few tire dealers around town and nobody had ever heard of a Toyo M55. Swell. A couple offered to order them in for some super-stupid high price--plus freight. I contacted a non-tire place that I knew could get Toyo tires and he was finally able to get them at a "reasonable" price. These things ain't cheap boys and girls. Oof. I had to pre-pay and sign a letter stating I would never even think of considering trying to return them. I left my pile-o-money and had them ordered.

In my research I found that the tire size, 285/75R16 preferred to be mounted on an 8" wide wheel. I had the BFGs mounted on 7" wheels which are the narrowest size listed for a 285. With the cost of these tires, I really didn't want to potentially shorten their life by putting them on a wheel that was too narrow for maximum life, so researched out a 8" wide 16" steel wheel. I had no luck locating a factory application for an 8" wide 16" wheel so I ordered a set from Wheel Vintiques. After I ordered them I got to thinking and after all these years and various vehicles I've had and modified, this was the first set of new wheels I had ever bought. I have bought many sets of wheels, but never a NEW set until now. Ironically, they look like stock wheels. So I get the new wheels and they are powdercoated black. Ugh, I don't want black wheels on this thing. I call around and get prices on re-powdercoating the wheels. The prices range from really expensive to beyond asinine. I then start researching painting over powdercoat. Come to find out, powdercoat works very well as a primer and with a light scuff takes paint beautifully. Sold!! I applied some white paint like every other steel wheel I have has on them and got the new tires mounted upon them. The first thing I noticed about these tires (beyond that they look pretty cool) is they stunk. Yep, stink, stank, stunk. Nasty. Smelled like some funky avian fecal matter. Took a long time to go away too. Wierd. Other than the stink they seem cool.

Here is one next to the BFG it is replacing: (for the same given tire size, load rating. load range, etc, the Toyo M55 weighs 7 pounds more per tire than the BFGs weigh)



All mounted upon the new wheels:



Now I have held off talking about these tires because I wanted to be able to give an accurate opinion of them. They needed to be put through some hell before I could honestly report on them. I will admit I was expecting them to perform well using the reviews as a baseline for judgment, but I have to say they have exceeded most of my expectations by a fair bit (except odor...LOL). I was pretty nervous about the sidewall construction. There are no real shoulder lugs or tread for that matter, just three concentric beads that are very uninspiring. I quickly found there is no reason for concern at all with the sidewalls on these things (or any other part of the tire). These things are as tough as titanium nails. I have aired them down and shown them no mercy whatsoever. My boy and I have put them through the wringer on some pretty sketchy trails and I have yet to permanently mark the sidewalls on these and it took several trips to find a piece of rubber chinked off the main tread of the tire. Absolutely amazing. The sidewalls have had the usual rock marks all over them, but as soon as it rains they look like brand new again. As it sits outside right now, two of the sidewalls are full of cactus needles of some sort. They don't care. At all.

I have had them in some different weather conditions. Dry, wet, no snow yet, some light mud. They seem to do good in everything so far. Road manners seem nice as well. Not as quiet as the BFG ATs, but not as weak as them either. Kind of a cross between an AT and a MT for noise. They do seem to do the Toyo drift to the right that I have read about on several of their tires, but nothing that bugs me so much I want to do anything about it. They handle wind and wet very well. I am quite impressed with the tires so far. I have had them on for about eight months now. I don't recall how many miles are on them though. I rotated them one time and they seem to be wearing great. One odd thing is they threw all their weights off at some point. I'm not sure if the original balance place didn't install them correctly or if when they are aired down they push the weights off, but I got them rebalanced and all has been well since.

[72MARIO]

Great choice on the wheel tire combo !

I have looked at those tires and that's the exact wheel tire combination I am planning on using when I build my longhorn 4x4 cummins chassis for my 67 c20 body. I currently have Toyo open country at2s and I really like them.

[lower50's]

Great story!! I love when ppl say something can't be done, anything can be done with enough time and skill and maybe some $$. The Burb looks amazing!! Great to hear you drive it all over that's what they are for.

[Average Joe]

Toyo makes a great tire. I luv the look of a BFG but Ive never been impressed with how they wear or their sidewalls. New combo looks great on the Burb btw.

[mosesburb]

Originally Posted by 72MARIO

Great choice on the wheel tire combo !

I have looked at those tires and that's the exact wheel tire combination I am planning on using when I build my longhorn 4x4 cummins chassis for my 67 c20 body. I currently have Toyo open country at2s and I really like them.

Thanks!! If these hold up as well as they seem to be so far, I don't think I'll be going back to BFG on anything this size again.

Originally Posted by lower50's

Great story!! I love when ppl say something can't be done, anything can be done with enough time and skill and maybe some $$.

I do heed warnings that things won't work occasionally, but if I can get things close in my head, I can usually pull it off in the real world.

Originally Posted by lower50's

The Burb looks amazing!! Great to hear you drive it all over that's what they are for.

Thanks!! I agree, these things were meant to be used.

Originally Posted by Average Joe

Toyo makes a great tire. I luv the look of a BFG but Ive never been impressed with how they wear or their sidewalls. New combo looks great on the Burb btw.

Thank you!!

[mosesburb]

So one of the things that has bothered me since I started driving this conglomeration of wayward parts is the location of the shifter knob in all three axis. There are a few contributors to the situation. One big one is the location of the shift tower where it comes through the floor. This was dictated to me by the placement of the motor itself and the fact that the shifter tower is integral to the transmission and not movable. To give some perspective on the situation, the shifter comes through a hole in the floor located right beside the factory hole for the transfer case shifter. Yes, that far back. Now, when I initially built the truck I bought a brand new shifter tower from GM and installed it. The shifter placement was great--if you were shifting from the back seat. Under the rubber sealing boot that comes on the tower assembly there are some screws that allow disassembly of the tower mechanism. I pulled the steel shifter stub out of the plastic base and heated it up and bent it into a much more agreeable position. This was a great improvement over the initial location, but after many thousands of miles, it has proven to be less than comfortable at times. Another situation exacerbated by the shifter location is the length of the stick itself. It ends up being too long to be comfortable, but too short to be cool. Something needs to be done to improve the physical properties of the shifter. The factory shifter is a combination of a solid stub at the top for a knob to thread onto, followed by a varying diameter tubing down to the bottom where a rubber isolator mates the shifter tube to a threaded insert which threads onto the shifter stub on the transmission. There is no easy way to do much of anything to this shifter except destroy it. Nothing productive will come from that, so another plan will need to be devised.

Now for something seemingly completely unrelated. When I installed the ARB locker in the rear I had done some research and found that the electro-pneumatic solenoid valves that control the flow of actuating air to the lockers were a "fairly" common point of failure. I quote fairly because while they are a quality piece, I did find several posts dealing with bad actuators and many people carry spare valves. I really didn't want to deal with all that crap. Why deal with an electrical switch sending power to a electro-pneumatic valve to send air down a plastic line to the locker when I deal with pneumatic valves in various configurations literally dozens of times in a day?? I'm not trying to win a beauty contest with this thing, so not much to worry about there. Let's go with something robust and simple. Big dumb parts--my favorite kind.

I decided to go with a parking brake valve from an air brake setup. Nothing fancy, just a simple on-off valve. I mounted it in the floor right next to the driver seat, right behind my big, dumb auxiliary battery disconnect switch:



It worked great. Out of the way, yet still accessible. Good stuff. That is, until, we were coming down a steep trail (<cough>cowpath/<cough>) and I had to do a multi-point turn to get down this switchback and needed a rear locker to keep from spinning the rear tires. If I went a little forward when I was trying to go backward, VERY bad things were going to happen immediately. So in the heat of the situation, I reach down to engage the rear locker and some stuff had slid forward and blocked access to the switch. Not good. I cleared the stuff out, hit the switch and locked the rear axle. This situation got me to thinking about my setup. I like it. It is functional 95% of the time, but that is the hang up. What to do?? Move the switch?? Go back to the electro-pneumatic setup??

So, back to the shifter situation. I decided the time had come to deal with the uncomfortable setup that I had. I knew I couldn't do anything with the stock stick, so a replacement would have to be sourced. I decided to take care of a couple problems at once with the shifter. I started by pulling the stub out of the base and doing some more strategic bending on it. It seems so simple. Bend it until it is in the right place, but what is the right place?? I thought I had it right when I did it the first time way back when. This proved to be a fairly challenging task requiring a few re-bends to get it "right". I eventually got it where I thought it should be. Now to add a stick to it. I was at the steel yard and picked up a piece of 1" .250 wall DOM tubing. Not having measured the length of anything I grabbed two feet to be safe. I had my buddy Russ bore the end of the tube and machine the threads into it. That worked out perfectly. I now had a two foot long stick in about the right place.



Now, what to do for a knob. I use a shift knob with a pneumatic valve in it hundreds of times a day. I have never had a failure with it. This is my kind of part. So I picked up an Eaton/Fuller A6909 shift knob. It has a pneumatic valve in the knob assembly that I can use for the rear locker.



My boy saw this and said I should leave it like that so it can be one of those "cool hotrods". I told him that I'm just not that cool and have to have something slightly more practical. Overall length. Oof. There's another fun task. I made a starting cut and I think I cut an inch off this thing three times and half an inch off of it another three times until I got to what felt "right".



Now that pic is slightly deceiving because the Eaton shift knob is fairly tall making the overall height of the new shifter closer to the length of the old shifter than it looks--still shorter than the original though. Now it is fairly obvious that the outside diameter of the new shifter is a lot smaller than the OD of the old shifter. I want to reuse the stock shift boot, so something will need to be made to deal with this discrepancy. I found a drop from my tie rod that Russ had machined for me. I took that back over to his shop and had him bore it out to fit the new stick and also cut a groove in the bushing to retain the top of the stock boot. This is what I received:



The shift knob mounts with 1/2-13 threads, so I cut the head off of a 1/2-13 bolt and installed it in the tube with a set screw. I retained the shift boot collar in the same fashion. This is what I ended up with:



After some plumbing and wiring for a possible future project, this is what I ended up with:



A different angle:



So, a lot of damn work for a shifter and ARB switch. Yep, sure was. Worth it?? Oh hell yes. Very much so. Much more comfortable position on highway and, almost more importantly, off highway. I find myself more likely to flip the rear locker on being that it is easily accessible now. One thing that I anticipated and was not let down with was the amount of noise the stick transmits. Remember the rubber isolator in the original stick mentioned earlier?? That is for noise abatement from the transmission. The stock stick does a nice job of dampening the vibration and not transmitting the noise to the interior. The new stick has no noise dampening properties at all. I thought this would be a big problem, but come to find out, it is really only an issue at certain ground speeds, under certain loads, so unless those criteria are met, no noticeable noise enters the vehicle. Win.

[Dieselwrencher]

Very nice! If you need another air switch later on, you can just get a shift knob for a 18 speed.

[Average Joe]

Great googly mooglies!! Thats a great gearjammer truckifacation.

[mosesburb]

Originally Posted by DirtyLarry

Nice work as usual buddy! You’re right, that shift tower does sit back pretty far. I never noticed that before until you pointed it out. Having an Eaton Fuller shift knob will definitely be a conversation piece. Most idiots will believe it is an Eaton Fuller trans and not know the difference…especially at the Overland Expo

Thanks!! Hardly anyone has noticed it so far. A car guy here and there, but not many.

Originally Posted by Dieselwrencher

Very nice! If you need another air switch later on, you can just get a shift knob for a 18 speed.

I actually considered it before I bought this one, but I really don't need instant access to the front locker switch, so I used the brake valve in the floor for the front ARB and went with a 9/10 speed knob.

Originally Posted by Average Joe

Great googly mooglies!! Thats a great gearjammer truckifacation.

Ha!! Thanks!!

[Dean'smeanmachine]

Sweet

[mosesburb]

Originally Posted by Dean'smeanmachine

Sweet

Thanks!!

[mosesburb]

So at some point I realized the rear axle housing was bent. My only guess is when we were on that horrid road out of Chaco Canyon and we accrued some frequent flyer miles some thing gave way. Don't know. Doesn't really matter other than I don't have a cool story to tell about it. Oh well.

Pulled the axle out and got some work out of the boy on the teardown:



Took it down and had it straightened, tubes welded to the center section, and a truss added to the top:



During reassembly:



All fresh and ready to go. The lube I drained out looked darker than it should have for the amount of time it was in service so I went with synthetic lube this time.



One thing I did change was I went with the later parking brake cable setup. It is the style that runs both cables down the driver side frame rail. It ended up being fairly easy and very well worth the effort. It will hold the truck in reverse, under power now, whereas before if it was on a hill I had to shut it off and leave it in gear to be sure it wasn't going to move.

Rear mount:



I had to make a new front mount for the stock Suburban cable to fit into:





While the axle was out I got a Daystar lower bag mount kit for the air bags. I had to make some plates to support the bag mounts. I don't have a cool circle cutter, so I hacked one out of a piece of tubing:



Plate mounted:



Bag mounts installed (it looks like the mounts are offset, but they are directly under the bag--just looks goofy in the pic):



This setup keeps the bags from becoming limiting straps when the truck is twisted up. They work great. I am surprised I did not have problems with over-extension of the bags before, but this removes that from even being possible now.

[Dieselwrencher]

Nice work on the bags and rear axle housing fix.

[Average Joe]

Quality work!

[mosesburb]

Originally Posted by Dieselwrencher

Nice work on the bags and rear axle housing fix.

Thanks man!!

Originally Posted by Average Joe

Quality work!

Thanks!!

[FRENCHBLUE72]

Housing looks stout now

[piratexpress1369a]

looks good and strong now

[mosesburb]

Originally Posted by FRENCHBLUE72

Housing looks stout now

Originally Posted by piratexpress1369a

looks good and strong now

I sure hope it is. That thing seems to get heavier every time I do something to it.

[mosesburb]

Soon after I installed the front ARB I learned that my air fitting into the front diff was going to be a big problem because of clearance (or lack thereof) to my ridiculous engine crossmember. A couple options were available. I could rework, or even better, remake the crossmember. While probably the best idea, it requires the most work and I really don't want to, so that is last in line. Another option was to bring the fitting out parallel to the diff housing instead of perpendicular to it. This has potential, but how to do it. I had it all figured out and was talking with my buddy Russ and of course he had a way to improve upon it in such a way that required his skill, time and machines. My idea was easier, but as usual, his was better....

He made a fitting out of stainless that mimics the ARB line fitting that threads into the bulkhead fitting, but instead of pointing straight up, it will point off to one side. Then he made a -03 JIC male fitting to fit into the other part. I stopped by his shop one evening to test fit the first piece into the housing and mark what angle I wanted the -03 fitting to come off at so as to miss hitting everything around it. Once that location was known, he bored a hole to accept the -03 fitting:



I silver brazed them together and ended up with this little jewel:



I was able to install it for maximum clearance around the vent line:



It looks like it hits and or touches everything, but it actually misses EVERYTHING!! It fits perfect and solved the problem beautifully!! Maybe I should discuss my crossmember situation with Russ and stoke the fire of creativity when he comes up with his great idea of how to improve the part....... Where's my phone??

[piratexpress1369a]

hey that is wild idea for sure

[Dieselwrencher]

Nice fix for sure!

[Average Joe]

Slick solution!

[mosesburb]

Back in June my buddy Lance and his janke hooptie and my family in our Suburban decided on an nice day trip up to Crown King via dirt. It is a nice, relatively easy trail and offers some very nice scenery. It all went well for a while until the mechanical mayhem began. My truck started running a bit warm which is something it never does. After that, Lances truck was running so lean that it was making no power and running warm itself then the battery launched itself out of the tray and ended up laying upside down on the motor melting the negative cable apart.

While we were stopped for something I noticed my truck had an odd sound coming from the engine compartment. It was a kind of ringing sound. Well, after some amount of time I determined it to be my Horton electromagnetic fan drive. Something was wrong with it and it was engaging and disengaging rapidly. I finally pulled the electrical connector to turn it off completely. This created a couple problems. One was the A/C had to stay off. No biggie for me and the boy, but I like to run it to keep my wife comfortable on the hot, dusty trails. The other problem is the electric fans will not keep the motor cool on a hot day like it was while pulling hills. This trail is almost completely uphill from south to north--the way we were running it. We were able to keep going and occasionally stopping to plug the fan clutch back in to cool the motor down while sitting still. For some odd reason it would still function sitting still. We'd cool the motor down, then climb the hill some more. We finally made it to Crown King and had a late lunch at the bar in town there. We went out the easy way and the electric fans were enough to keep it cool without stopping (even with the A/C on). We made it home later than anticipated, but intact, with nothing blown up.

So, what happened?? After much investigation, I found that where the wires enter the coil housing they had some damaged insulation from getting into the fan a few years back. I had repaired the wires, but I didn't realize at the time the wires had been damaged at that place. The wire/s were broken and *just* making contact (occasionally--thus the ringing sound).



I started researching repair options and I quickly found there are exactly NONE. Nobody fixes these things. I had read that Horton will service them so I called them and got a very nice, helpful lady on the phone who explained that they do nothing to fix them. Horton will fix or sell rebuild kits for their pneumatic fan drives all day long, but not these. They will sell a new one, but this one has been discontinued for many years (long before I bought my NOS unit). There was really nothing she could do to help. I found a place that had an old Horton fan drive that I could check out and buy the piece I need, but the wires were damaged just like mine, so that was no good. I found a manufacturer's sticker and part number on my clutch and called a motion industries establishment with the information. He went so far as to contact the manufacturer but found that it is completely proprietary and only sold to Horton. Uuuugh!! I finally found a brand new clutch assembly on the ebays and got it for a very reasonable price. It was not the same as what I had, but I was rolling the dice that I could make the coil work with my clutch. It turned out that I could. I pulled the coil off the old one and installed the coil from the new one:



So while all of this was going on (several weeks), we had other trails to run so I picked up a stock fan clutch from Dodge to hold me over until I found all the aforementioned parts. I had picked up an aftermarket Hayden fan clutch, but I really hate aftermarket viscous fan drives. The clutch on the left is the OEM Dodge unit and the one one the right is the aftermarket Hayden unit. The differences are quite apparent:



It worked good, but reminded me how much I love the Horton. The Horton is on or it is off, no in-between. The stock unit is always on. Maybe just partially, but never completely free-spinning like the Horton. It makes more noise than the Horton and doesn't cool any better. I was ecstatic when I got my repaired Horton back on the motor.