90 suburban towing questions.

[syoungs]

so now that I have purchased my suburban, and got a few runability things adressed (tuneup, tie rods etc), I am ready to start building it a bit.

first things first, I am getting rid of the 10 bolt rear, right now the truck is lifted 4" with 35's, it is a bit underpowered, but honestly im ok with it. im sure after a cam swap and ultimate tbi mods, it will suit me just fine.
scouring junkyards for a 3/4 ton rear axle, and have found a few that are geared at 4.10. I dont plan on running any larger then 35's, and am kicking around the idea of switching to 33's after the swap. I can pick up a front 10 bolt, with matching 4.10's, already with an 8 lug pattern, for around 200$.

my questions, will 4.10's vs 3.73's be a noticble difference? I figured for an extra 200$ and some labor ( my own labor), it was a no brainer, especially considering I would need to buy the parts to swap my front end to a 8lug anyhow.

the tranny has been rebuilt with a shift kit of some type. It was done when I bought it, I plan on running it till it either fails, or till august, when It will get most likely a bowtie overdrives 700r4 to replace it. or a monster in a box rebuild.

I will be towing a 20' aluminum jet boat, probably 4500#, and a 20' camp trailer thats close to the same weight, and mostly local towing at that. longest I would run with the boat is 45 miles, longest I run with the camper is just about 150.

 

[82fb]

with a tbi 350, you want all the gearing you can get. So, yeah, 4.10's, and switch to 33's after you wear the 35's out. Install huge tranny cooler, and make sure your engine cooling system is 100%.

I have towed with a 90 suburban. I think I had the 3.42 gears with about 30 inch tires. 24ft travel trailer, weighed about 6k loaded. Towed up long grades several times. Did okay, and would keep pulling that load at 40-50 mph up Pacheco Pass near San Luis reservoir if you are familiar with central Californa. However, my cooling system was suspect and I would stop if(when) it got hot and let it cool for a few minutes.

 

[Reece04]

So I have basically your same setup, 90 burb except I have 33's... I had really no issue on the free way with the 3.73 stock setup, but when I would hit the long grades on I17 heading to Flagstaff, I would struggle to do 45mph... I have since had the rear end replaced with a semi float 6 lug 14bolt with 4.11... huge difference, I can now use my cruse control on the freeway, and when towing (6,000 lb boy scout trailer) I can do 75-80 on the flats, i am just getting 6-7mpg... the hills I still have some struggle with, I am not setting any speed records but I was afraid that if geared it too high (or low, never really figured that out) to 4.56 I would lose top speed, so I thought 4.11 was a happy medium.

I really like my setup, again, it is a 24year old truck now, and with 210hp it is not setting land speed records, but it has plenty of punch off the line for a big ol truck, and I rarely have any real concern about pulling any trailer.

I will second the Tranny cooler, I had my 700r4 rebuilt at about 80K miles because I pulled a 4,000 boat to the lake and it was all mountain, and i blew the 3 and 4 gears. still got me home (200miles) with the boat, but it cost a paycheck to get it rebuilt.

The gears were kind of the same deal, I was hauling a trailer up the mountain for scout trip and I started noticing a weird sound out of the rear end, turns out when you start shaving off teeth on your ring gear, they make funny sounds. anyway, needing a new ring and pinion anyway, it was time to upgrade the little 10bolt to a more stout 14bolt.

Good luck, 33s with a 4.11 work great!

 

[syoungs]

any idea what your non towing mileage on hiway is with 33's and 4.10's? Im honestly pretty satisfied with the performance as is right now, figure I can get it a little boost with a few low dollar upgrades and will be more then happy with it.
I am already planning on a tranny rebuild in august, just so I know what it is, and how its built. it wont see to much towing duty really, and we are even kicking the idea around of selling off the camper and going to a tent trailer, or just sticing with a tent. I think that even if I stay with 35's, I will be ok, I am in eastern washington, and do not really have any major pulls to where I go with the boat or trailer in tow, pretty much flat land. fact is I used to tow the boat with a 3.4l tacoma that had 280k miles on it, stock gears, and 33s.