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1991 GMC V3500 Project

All I've read or heard from tuners is that Holley doesn't have even half the capabilities as you do with the factory ECM/TCM through HPTuners... so, it's probably pretty limited compared to what you were able to do. I need/want to learn it though, just don't want to mess anything up which I heard you can do pretty easily...
 
centexk5 said:
Sounds like every modern trans I know. My tundra will drop into 6th gear at 30-35mph as fast as it can and doesn’t like to downshift without some decent throttle input. And that’s after it’s tuned. Same with my previous 14 Chevy with a tune. It’s irritating for sure.
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Th400 been doing this for decades before these trans ever come about .
 
Its like the skip shift in the t56/tr6060, 1->4 when under x% throttle. So annoying until eliminated.
 
Ok, need some help guys. These Prothane upper shackle (in frame) bushings were replaced about 5,000 miles ago. They looked fine when I inspected them during the motor swap, this is what they look like after 150 miles (they did not get torn up while removing). The headers are closer than than the down pipes were but only by an inch or two. The passenger side has bout 2" between the bold and the header, and the drivers side about 4". I assumed they melted so added additional heat shielding today. Out of curiosity I took a video while stationary but turning the steering wheel in each direction 360 degrees. Look at all this flex!!! No wonder they're beat to shit... what are you guys doing about this? Is a custom panhard bar really my only option? I'm also thinking about adding a custom frame brace in this area to try to stiffen the frame up.

IMG_2063.JPEG

View attachment IMG_2062.mov
 
I wouldn't think that a 1 ton truck would need much stiffening of the frame unless it is overloaded. But that's just my thought.

As far as heat, I know that my '70 K10 has far less clearance there. I had to trim the end of the bolt just past the nut to make it clear the header.
 
6872xtc said:
I wouldn't think that a 1 ton truck would need much stiffening of the frame unless it is overloaded. But that's just my thought.

As far as heat, I know that my '70 K10 has far less clearance there. I had to trim the end of the bolt just past the nut to make it clear the header.
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I didn't think so either. I don't know what would be overloaded though besides the size of the tires. I would think everything is improved; lighter drivetrain, crossover steering, steering box frame brace, etc.

I think I have a few things going on that I'm going to work on this week. I have 13.3 degrees of caster... far too much so I just ordered some 4 degree shims. I don't like the longer 6" shackles but the free arch on these new ORD 7" springs is too much to fit the factory sized 4.5" shackles (they won't reach for install). I also think that with 37" tires, with this much caster angle, it puts a lot of pressure on the suspension when turning the wheel. I do think the video is the extreme example as I was sitting in the driveway and not moving, something I never do.

As far as the heat goes, I didn't think it would get that hot either but this motor is running about 11:1 compression and a good amount of timing so maybe that's a differing factor.
 
cheavyk10 said:
The FUSH kit from ORD upgrades the bushing size and material to kevlar, as wasting these bushings is a common problem.
www.offroaddesign.com

'73-91 GM Front Upper Shackle Hanger Kit

Includes greasable bushings and bolts and hardware to attach bracket to the frame.
www.offroaddesign.com www.offroaddesign.com
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I actually just realized when ordering the shims from ORD, these black bushings were actually the Kevlar bushings from ORD, not prothane. I replaced with prothane, we’ll see what happens. I’m not sure how a larger bushing will help me since this thing only goes off-road maybe twice a year.
 
The same deflection over a larger bushing would help them last longer but a panhard bar is going to control the side to side movement.
I personally think that particular flex is an unavoidable side effect of the leverage tall springs put on the stock system design.
 
obijuank5 said:
The same deflection over a larger bushing would help them last longer but a panhard bar is going to control the side to side movement.
I personally think that particular flex is an unavoidable side effect of the leverage tall springs put on the stock system design.
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Yea I think so too. I may be going back to the 4” springs and 35” tires, but we’ll first see how it does in west Texas during hunting season this fall. Just want to get it the best I can. I know coilovers are in this trucks future but not now…
 
All the poly bushings wore out on my Suburban (Rancho), I recently replaced them (ORD). The ones on my crew cab are showing signs of drying out and cracking but are still serviceable. (ORD) They aren't as durable as they claim. (Any manufacturer) They see a lot of stress on a big truck with a lift. Swap them out and plan on doing it again. Replacement rubber ones aren't very good and I haven't found an indestructible poly one yet.

I don't see a Panhard bar doing anything but causing binding on a leaf spring suspension.
 
sethgmcv3500 said:
Yea I think so too. I may be going back to the 4” springs and 35” tires, but we’ll first see how it does in west Texas during hunting season this fall. Just want to get it the best I can. I know coilovers are in this trucks future but not now…
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This beautiful truck is going in the woods?
 
HankScorpio said:
All the poly bushings wore out on my Suburban (Rancho), I recently replaced them (ORD). The ones on my crew cab are showing signs of drying out and cracking but are still serviceable. (ORD) They aren't as durable as they claim. (Any manufacturer) They see a lot of stress on a big truck with a lift. Swap them out and plan on doing it again. Replacement rubber ones aren't very good and I haven't found an indestructible poly one yet.

I don't see a Panhard bar doing anything but causing binding on a leaf spring suspension.
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A parallel to the ground at ride height panhard bar wouldn’t bind up with these springs. The axle has a lateral range of 2-3” as it is, a panhard bar would limit that range of motion to less than 2” I’d guess. But I’m with you, I don’t like the idea of it
 
Truckman4life said:
Are the shackles cross tied or just individual side bars?
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They’re not cross tied. I actually bought some new ones that are a while back thinking that could be my problem but after the new bushings were installed I decided to reassemble with the ORD HD ones and there’s no shifting with them (I don’t know how else to explain it). There’s pins inside the bushings that the bolts tighten down on so they move together as one.
 
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