1st Square HELP!!
 

Hi all,

So I recently purchased my first square body. I have no experience with these vehicles and the "GM Pull" issue.

It's a 1985 Chevy K10 350 with new brake hoses/pads/calipers from previous owner who did a pretty thorough restoration (lets say 1 year old). Pretty much new everything under the hood but I guess he was selling it for a reason.

I really want to take it out on the highway but just riding around the fields @ 40 mph a semi light tap on the brakes throws the vehicle HARD to the right. I mean, it's scary!!! Now, it doesn't do this all the time. It also throws harder to the right the faster I am going. At lower speeds just putting around the property it will every now and then lightly pull to right but I also have just been lightly tapping on brakes. It does not pull to right when not on the brakes.

A few fellas around that had these back in the 80's say "they all did that" I just can't imagine driving a vehicle safely that does this.

Any help is greatly appreciated.

Right now I am replacing BOTH fuel tanks as previous owner did not disclose they were leaking. Talk about dangerous. I'm dying to get on the road and in the woods but feel to unsafe as is. Ordered 16gal replacements from LMC.

Anyway, thanks and look forward to your help! If I need to post pics to help figure out the problem just tell me!

Re: 1st Square HELP!!
 

There is absolutely no way that that's normal operation, there is something wrong with your brakes. Check your whole brake system out. Take the wheels off and look at each brake, how does the pedal feel? Are any brake cylinders leaking?

Re: 1st Square HELP!!
 

I would start with replacing the brake hoses. If that plus a good bleeding doesn't fix it, I would change calipers.

Re: 1st Square HELP!!
 

thanks for replies guys.

i admittedly have pretty much zero car knowledge. that was part of the draw of buying this vehicle. learn as things break kinda thing.

i have a mechanic who inspected the hoses and calipers to which he said both looked new. however, from reading on here i see you really do have to take apart the hoses to see what's going on inside.

as for calipers, he says they also look new. but i will suggest we take both apart and replace if needed.

any recommendations for supplier of new hoses/calipers?

thanks again

Re: 1st Square HELP!!
 

Well - they didn't all do that, but enough of 'em did that to keep my children fed...

Some of them were bad enough you could drive all the way home without touching the steering wheel (assuming you could make right turns the whole way).

Good advice above with the caliper and hose replace. This might be obvious but one thing I would add is that if it goes hard to the right that means the LF caliper is deficient (as opposed to the RF being an "overachiever"). Corrosion inside the caliper can cause this, as can a rough surface finish allowing the piston to cock/wedge in the bore (very poor L/D ratio in the original design).

The other thing is that during deceleration axle windup can cause a RH steer input.

Because of the fore/aft steering drag link, rolling the top of the axle forward (as in deceleration) wants to compress that drag link. That results in either (a) the steering wheel rolling to the left, or (b) the road wheels being physically steered to the right.

A lot of brake issues were masked or misdiagnosed (or exascerbated) by this "designed in" anomoly. Watch for it as you do your testing. It can be minimized by adding three leaf front springs or designing a kind of reverse "traction bar" set up to control the axle wind up.

Once the customer was sensitized to this they could be super picky. When we would fix customer complaint vehicles or buybacks at the Proving Ground we would do both the brakes and the suspension fixes, just to be sure.

K

Re: 1st Square HELP!!
 

My Impala has a rear axle leak and my brakes pull very hard to the right on the first few stops. Once the shoes get cleaned up some the braking is more normal. It's on "the list" to be fixed but it has been a few years so far. Just more food for thought and something to watch for while you are inspecting the brakes.

Re: 1st Square HELP!!
 

thank you all. i will inspect everything you guys tell me to.

re leaf springs, it does have leaf springs on both sides but i will double check that everything is good to go there.

it's raised 4" i believe and after discovering the gas leaks, i noticed the truck was higher on the left side than the right. i'm sure it's a shock issue and has nothing to do with the right brakes but just thought i would mention it.

i was told the axles were dana 44's. do i need special brackets for brake calipers to install?

i'll include a photo for axle identification. as well as photos of left and right calipers and the truck tilt (kind of hard to capture)

first caliper photo is left front and second caliper photo is right front

thanks again for your help!

Re: 1st Square HELP!!
 

Those are some pretty beefy front springs so you can probably disregard everything I said about axle windup.

Shocks shouldn't affect the way the truck sits, since they are a "neutral" device when at rest (they work to dampen motion).

K

Re: 1st Square HELP!!
 

x2 on it shouldn't do that. Mine doesn't.
x2 on underachieving LF brake.
x2 on no axle windup with those big springs.
x2 on the unevenness being spring sag, not shocks. Normal with the driver always on that side. I always empty my LH tank first, so the RH tank is a little extra weight to balance out. Also, if you have a toolbox or sandbags or something you carry in the back, load heavy to the right to compensate the driver weight since we normally drive one-up.

That front axle is a GM corporate 10-bolt. The Dana 44 does not have the little square tabs on the bottom corners.

Re: 1st Square HELP!!
 

10-4. thank you.

so, i'll start by replacing hoses/calipers/maybe pads while i'm at it.

keith, thanks for your expertise and explanation re shocks. as i mentioned i seriously have zero clue when it comes to vehicles. i am a total newbie!

rich thanks for clue as to sag and tips. should i look into replacing spring or just abide by tips to reduce appearance of sag? also, thank you for axle identification.

i will include rear axle photo as well as i assume it is also a gm 10 bolt?

Re: 1st Square HELP!!
 

Replace hoses, calipers, pads and discs. No sense not doing the discs while you are in there. They're cheap, and will be differently worn due to the existing braking issue.

I keep a few hundred pounds of chipped rock in the back to throw under the tires during the winter if I get stuck. These come in 40# bags. If you do something similar, just stack them on the RH side of the bed. The sag will even out.

The rear diff looks like a Dana 35 to me. Not sure.

Re: 1st Square HELP!!
 

thanks rich.

looking at truck again this afternoon, i realized it's the passenger side of truck that's lower than the driver.

probably the spring on that side. strange as you would think it would wear on driver's side first.

i will go ahead and replace all the things you mentioned. should i do anything to the rear while i have it in the shop?

thanks again!

better photo of lean (ignore bumper as that is crooked from previous owner)

Re: 1st Square HELP!!
 

So? Pile anything heavy on the driver side. Things don't always settle the same.

You should inspect the drums and shoes, and change the shoes and machine/replace the drums if they need it. Also inspect brake lines and cylinders for leaks, dry rot, etc.

I also ended up replacing my master cylinder, because the little rubber cup on the end of the piston had age hardened. If the pedal slowly sinks as you hold the brakes continuously while stopped, that's the symptom I was seeing.

Re: 1st Square HELP!!
 

i gotcha. i didn't know if driver sag was normal and passenger side may indicate a problem. just checking! the funny thing is i didn't notice it the day i got the truck.

i just want to be sure everything is safe before i take her out on the highway.

i will be traveling about 70 miles to and from hunting camp this winter and just want her to be reliable. my main concern before getting the truck was the gas tanks (due to fire concerns) and the brakes/axles.

i appreciate your help and will post a follow up after replacing all suggested.

Re: 1st Square HELP!!
 

It appears to me you have a bad right rear leaf spring in that photo. If you notice the cab is straight and the bed is crooked. Mine did that once then I realized there where 3 broken leafs and that was causing the bed lean. I would check you rear leaf packs and probably replace them before they get to bad.

Re: 1st Square HELP!!
 

I blew up the picture and played with contrast and don't see it, but could be.

Definitely inspect that side and see if you have one or more cracked leafs.

Re: 1st Square HELP!!
 

dfrank, thank you for your input.

yes, i kind of have a feeling it might be more than just sagging (though i don't know just a feeling). i will inspect in daylight tomorrow for cracks and will upload a better photo for all of your opinions.

i truly can't thank you guys enough for your help.

i feel overwhelmed and discouraged at the moment that i made a bad decision in purchasing the vehicle and that i bit off more than i can chew. i love the truck and paid a pretty penny for it but it wasn't supposed to fall apart so quickly lol!

Re: 1st Square HELP!!
 

Inspect the leafs, spring bolts and bushings, shackle bolts and bushing, spring and shackle mounts, shock bolts and bushings, and shock mounts on all four corners while you're at it.

Hey, you could have paid 5 or 10 times as much for a new one, have it depreciating by the minute, and never have anybody call out "Nice truck!" as you drive by.

In any truck you buy and keep, eventually you replace brakes and suspension anyway, you just get to do some of it up front is all.

Re: 1st Square HELP!!
 

What is the concern about the gas tanks?

K

Re: 1st Square HELP!!
 

I wouldn't regret the purchase. I looks like you got a great truck. Any used vehicle you buy is going to need a little work to get it right. Like rich said a new vehicle goes down in value every year, but a classic truck like you got goes up in value every year. Heck I am trying to find another 73-87 chevy/gmc truck and then sell my newer tahoe and just drive the old chevy around while I restore my 86 k10. Why might you ask. Cause I will appreciate it more. The newer cars are no fun to drive in my opinion. And parts are usually cheaper for these trucks than tbe new vehicles.

Re: 1st Square HELP!!
 

amen to that.

yeah, i'm definitely with you guys as far as used vs new for sure. in fact, when i get this truck going, i doubt i'll ever touch my chevy avalanche again!

what happened is after looking for a long time, this truck appeared but it was out of state. long story short, i didn't physically inspect the vehicle before purchasing. the guy lied about a lot but that's on me for buying it w/out physical inspection.

with that said, i do think it's a solid truck. i had 3 offers for it the day i brought it home and they keep coming.

i'm just wondering if mechanically challenged me bit off more than i can chew.

as far as fuel tanks, i filled up for the first time (both sides) and parked it. after about 2 hours, i came back and there was gas on the ground on both sides. and not just a little. it came with no exhaust pipes so the leak on drivers side is right by muffler. i was told not to drive it. i'm not sure exactly where leak is coming from but i will find out when my mechanic looks at it again to replace. on the top somewhere i was told.

i went ahead and ordered 2 new 16gal from lmc with 2 sending units. hoping current sending units are still good and i can get a refund.

i do have a question for you guys with duel tanks: my fuel gauge shows half full when switched to left tank. how does the fuel gauge work with duel tanks? only half full at any one time? when i switch over to full right tank (with car off) the gauge doesn't move.

Re: 1st Square HELP!!
 

Gauge will only read correctly with the power on.

Gauge shows condition of whatever tank it is selected to. Full when DS selected means driver side tank is full, but says nothing about the other tank, and vice versa..

Re: 1st Square HELP!!
 

thank you. that's what i feared.

it only showed half full on drivers side when it was actually completely full and truck was running.

thank you for explanation. now i know correct way it should read going forward.

Re: 1st Square HELP!!
 

x2.

With any vehicle purchase (new or used) it takes a little while to get it sorted out and make it your own.

K

Re: 1st Square HELP!!
 

One thought that occurred to me... You mentioned that the calipers were changed by the PO. I've had experiences over the years where the wrong caliper was in the correct box. There are a number of calipers with different piston bores that have the same mounting ears. Maybe your two front calipers aren't matched, leading to the left side being weaker.

Also, make sure the front flex lines are in good condition. I've had problems before because the inside of the line had collapsed.

Good luck!