New to squares

[Abomb1]

Hey guys, I just bought an 88 Suburban that I plan to use for a daily driver. Coming from a 2012 Infiniti QX56 I've noticed 1 or 2 differences. I got tired of the expensive repairs and check engine light so decided to go a completely different direction and get something easier to work on and a little more simple. I'm no mechanic, but I do play one in my garage if I think I can do something myself and there is enough info/pictures online to get me through it. So far I really like the Suburban. My drive to work is 30 miles each way on an interstate though, so I really wish the truck drove and sounded like it does at 60 when I'm going 80. That might be asking more of it than I should be though. It has a 4 inch lift (I think) and 33" tires. Unfortunately I don't have a lot of background on it since it came off a small dealer lot, but I'd love to know what gearing it has and should have. I checked the RPO codes and it came with 3.42 gears but I don't know if whoever did the lift also changed gears. It tooks to be in really great condition, someone took care of it.

Here's a few pics:

[kwmech]

Really nice looking ride. More often than not the gears do not get replaced. How accurate is the speedo? My '91 has 3.73 gearing and I'll be changing it to 4.56 when I go with the lift and the larger tire

[Abomb1]

Thanks. The speedo actually reads higher than actual speed. When it says I'm going 60 my GPS says I'm actually going 55.

There's also a switch added below the steering column that I haven't been able to figure out. When off it seems to shift better in town. When on its like it tries to hold a higher gear until it absolutely has to shift.

[68Timber]

It sounds like the switch is controlling lockup of the torque converter. Easy enough to verify, just get it up to high way speeds with the switch off and at a steady speed, then turn it on and see if you get an rpm drop.

When you say it sounds better at 60 than 80, how do you mean? Wind noise, engine rpm or strain, tire noise, ?

Beautiful truck btw, and welcome to the forum.

[Abomb1]

Thanks for the welcome.

I tried flipping the switch at a constant highway speed and didn't notice a change in rpm. But it does seem to want to get into 4th a lot faster with the switch on.

The difference I notice between 60 and 80 is engine noise and strain I guess you could call it. At 80, any slight throttle push will cause it to downshift get up to speed and upshift again. Feels like it's hunting too much for gears as hills are a constant back and forth between drive and overdrive. I'm guessing changing my gearing could help that, but would have to know where I'm starting from for gears and what would be ideal for my mostly highway driving.

When I decided I wanted a square suburban I really want looking for one lifted this high or with 33s but this one showed up locally in such good condition and I really like the way it looks. I know it'll never be an ideal highway driver, but if I can make it a little more comfortable at interstate speeds, I will.

[Ski-me]

The only way to tell for sure is to pull the diff cover off and see what's stamped on the ring gear. Might be worth changing the diff fluid anyways.

Stamping:
41:11 - 3.73 gears
41:10 - 4.10 gears
41:12 - 3.42 gears

These trucks aren't known for a lot of strong power, especially trying to hold 80 MPH. With the 4" lift, you're pushing a LOT of wind at that speed. With the 4 speed auto, I almost always downshift when I hit the gas on the freeway.

Changing gears really can get expensive, so usually not worth it. Does it feel pretty quick from a standstill? If so, that might imply a lower gearing axle....and if your speedo is reading higher than actual, also points to lower gears a bit. OR, maybe someone tried to just change the speedo gearing rings at the t-case.

3.42's and 33's at highway speeds are not going to win any races.

Great looking truck though! How's the interior and underside of truck? WI rust?

[68Timber]

I wouldn't say re-gearing is not worth it, it's just expensive. I had a C2500 crew cab with a small block once that was lazy. Swapping from 3.73 gears to 4.56 gears totally transformed the truck. You're looking at a grand easy to re-gear your Burb front and rear but it will make a big difference if you're running 3.42 gears now. Like Jeff said, pull the cover and see what you've got.

[Ski-me]

Originally Posted by 68Timber

I wouldn't say re-gearing is not worth it, it's just expensive. I had a C2500 crew cab with a small block once that was lazy. Swapping from 3.73 gears to 4.56 gears totally transformed the truck. You're looking at a grand easy to re-gear your Burb front and rear but it will make a big difference if you're running 3.42 gears now. Like Jeff said, pull the cover and see what you've got.

yea, I originally had 3.42's on my blazer and ran up to 33's. I have since changed axles and gearing. Now at 4.10's with 35's. I did drive around with the 33's for awhile and that was a really nice balance. Will admit, 35's did take a little from the power department, but I like the look better than the 33's (And so does my wife!) I'm also driving at 6500' elevation. At 2500', that does help the truck.....depending on your elevation.

Just so you know, 87' was first year of fuel injection so you picked a nice one. Still separate belts on the engine vs. a single serpentine, but otherwise, a lot of the same things up to 91'.

I also like the maroon interior! It's pretty cool!

[Abomb1]

Originally Posted by Ski-me

yea, I originally had 3.42's on my blazer and ran up to 33's. I have since changed axles and gearing. Now at 4.10's with 35's. I did drive around with the 33's for awhile and that was a really nice balance. Will admit, 35's did take a little from the power department, but I like the look better than the 33's (And so does my wife!) I'm also driving at 6500' elevation. At 2500', that does help the truck.....depending on your elevation.

If I really have 3.42s still and were to switch for 4.10s, is that going to hurt my mpg? Right now I'm at 11.5 so I'd rather not drop any more mpg.

I like the maroon too, my grandpa had an early 80s truck with it and I wasn't as much of a fan then. Now it reminds me of him.

[Abomb1]

Sounds like I should change the differential fluid this weekend and figure it out. It does seem to take off pretty good from a stop.

It came from North Dakota, and either has 45k miles or 145k miles. Interior is VERY clean. It has had extra undercoating added so not bad underneath. Here's some more pics inside.

[Ski-me]

It depends on how fast you drive it, but no, MPG don't really change much in my opinion. You're getting the engine in a better power zone by gearing lower, so the engine doesn't have to work as hard.....so better MPG. But, it's a large truck that's lifted, so in reality, I don't think you'll see much of a change either way.

Excellent condition! It looks like your dash is uncracked too! I bought an OEM one for $500....now those are pushing $1200-$1500 for OEM dashes!!

Anyways, tons of info here and always willing to help out in any way. You found a keeper!
Original radio too.

I just use general gear oil from Valvoline. Around $7/Quart.

[Ski-me]

Get your VIN and run a Carfax. Then you can look at the history, registration, service, etc and might be able to see the odometer readings and determine if it's over 100k or not.

I did mine and saw the history roll over 3 times. I have 365k on mine and did change out my speedo for an extra digit speedo and had a shop dial in the correct mileage. Kinda cool....

[Zook75]

I had a silver and red Burb in the late 80's, Loved that thing.. yours looks like a very sweet ride for sure.

[kwmech]

I used to have a different suburban I had regeared to 4.10. Wasn't enough with the tire size, weight of the 'burb and an overdrive trans. Of course I had 3.73 in that one also, so it was only a 9.1% difference. I was also towing a small travel trailer (26') at the time. It will definitely be 4.56s this time.

Look at the spid on the glove box door if it is still there. It will be a G code like GT4 (which is 3.73) or something similar. G80 is posi

[frenchy51]

cool burban-way to go! Welcome to the asylum....

[Abomb1]

Thanks for all the welcomes and info so far, I've definitely learned a lot from this site.

The codes in the glovebox don't show a limited slip rear, and from the snow and ice I've been on so far I don't think there's one in there, but I guess I'll see for sure when I open the rear diff.

I also was able to do a vehicle history report and found that it definitely has over 100k miles on it.

Dash is not cracked other than a couple small ones over the speakers between the little holes there. Should I be looking for a cover for it to keep it from cracking or does this happen when people are taking it off and putting it back on again?

[mongocanfly]

that is a sweet burb.....before you jump on the changing of gears part ,you need to do the math and see where your at...im not against changing gears for benefit...but ive seen people go from say 3.42 to 3.73 only fuss about it later....thats to close on ratios and isn't much diff than a new set vs worn out set of tires.....sometimes it takes a big jump to get you to the sweet spot you need to be....
http://www.csgnetwork.com/multirpmcalc.html

[mongocanfly]

with 33" tires and 3.42s at 80mph with od gear of .7 (guessing)...you would be turning around 1950rpm at 80mph....at 60mph your only turning 1463rpm

at 80mph with other gears it would be..
3.73=2127rpm
4.10=2338rpm
4.56=2600rpm

[kwmech]

I'm tell'n ya....4.56 with the overdrive. That low of an RPM kicks the converter in and out and lugs the engine. Small blocks seem to be happy cruising at 2200-2500 rpm. I'll be running 285/75r-16s which come in at about 32'' tall

[Edahall]

These trucks were not really designed to drive at a sustained 80 mph cruising speed. With an anemic 350 engine in a lifted 4x4, the engine will be close to maxed out at 80 mph. I would look into installing a larger engine like a Cummins 5.9 turbo diesel or a 8.1 Chevy gas engine. The 8.1 will still get poor fuel at 80 mph but you would have some throttle to spare while the Cummins will still get around 17 mpg at 80 mph. I would also get rid of the lift and get some tires rated for high speeds. Having a blow out at 80 mph in a lifted truck is not fun and sometimes fatal. Also look into upgrading the brakes. Convert to hydroboost and rear disk brakes.

[Ski-me]

Engine swap is a super expensive, time consuming option. I would drop the lift to 2.5" and then if absolutely necessary, drop the tire size to 31" or 32". Otherwise, I'd just drive it as is.

If it was me, I like the look of 33" tires with a 2.5" lift vs. a 4" lift. I personally think the 4" looks too high for me.

This does look like a 1/2 ton truck (6 lug wheels), so should have the 4 speed OD, 700R4 tranny.

[Abomb1]

Engine swap is an expensive option I'm not ready for now. I wouldn't mind dropping it down to a 2.5" lift though if I could get by without spending a bunch of money to do it. Guessing it would require different front leaf springs and a shorter block in the back? I should still be able to use the 33's with the smaller lift?

[Ski-me]

Originally Posted by Abomb1

Engine swap is an expensive option I'm not ready for now. I wouldn't mind dropping it down to a 2.5" lift though if I could get by without spending a bunch of money to do it. Guessing it would require different front leaf springs and a shorter block in the back? I should still be able to use the 33's with the smaller lift?

Yes, usually no problem at all. I'm running 35" tires with a 2.5" lift.....slight rubbing if I hit a big bump while turning, but haven't really had it happen in several years with this setup. Rim size for me is 15x8. You may have 15x10....hard to tell.

You could get BDS front springs or Tuff Country. Then new blocks in back and new Axle Ubolts. The only question would be the shocks that are mounted. Some can handle a little bit of drop, but you'd have to check out the model numbers to see if it could handle the lower ride height.

Here is mine with a 2.5" lift and 33" tires.

[Ski-me]

And just for fun when I first bought it....

37" tires on 2.5" lift. Yea, didn't last too long after I bought it!

[Edahall]

One no added cost thing you can do to keep the transmission from hunting between overdrive and direct drive at 80 mph is to manually select 3rd gear on the column shift. This would keep the engine in the max power band, possibly increase fuel economy and prolong the life of your transmission.