GM Frame build - Observations and question about cent bolt for leaf springs. - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**71CHEVYSHORTBED402** · 06-15-2015, 10:34 PM

(71 Custom Deluxe - 1/2 short fleet)

The front bed brackets don't match. They're the same part, but the mounts have a short "flare/wing" on both sides at the top, only one side of the flare is shorter than the other on both pieces. One was "reversed", and they simply don't match (hardly noticeable). GM worker figures it works either way, so don't worry about it. 50/50 chance they'll match anyway...ha!

The center rail on the frame under the bed is off square by about 1.25". Not sure why that is, maybe to add strength. That or it doesn't matter. Is that common?

That center bolt "tie-bolt"for the leaf springs ("tie-bolt").......... the mount is notched so you can slip the head of the bolt in, right? As far as I can tell, there's no other way to get a bolt in there.

Thanks for any input.

**71CHEVYSHORTBED402** · 06-16-2015, 11:52 AM

ttt

Lees68GMC · 06-16-2015, 12:19 PM

Ive been looking for quite a while for new springs to lower with, maybe 2-3 inches and don't want to flip kit. My GMCs springs are only 2-1/4" wide but are stiff (spring rate). And YES that cross-member is crooked in all of them

**71CHEVYSHORTBED402** · 06-16-2015, 10:51 PM

I suspected so. Probably adds strength. That frame of yours looks familiar, only you're ahead of me. I'm just in paint removal mode. Exhaust, brakes and shocks come off later. Maybe the springs........certainly the u-Bolts for them.

Safe to say the mount for the center bolt for the leafs is notched, so you can get the head of the bolt into the mount? I guess I'm looking for confirmation Really, it's the only thing that makes sense.

I've been thinking about a drop myself. My brother says losing one leaf spring gives you 2", then all you need is different coil springs on the front. I've done a little homework, and at this point I'm calling BS. Unless I can hire someone to do it the right way for under $1200, it's just not worth it to me........ALREADY A MONEY PIT. Ha!

BrianG · 06-17-2015, 10:03 AM

The bolt that goes through the center of the leaf springs has a round head, not hex shape like a normal bolt would. Sort of like an Allen type of bolt, but I don't think the original ones had a place to put an allen wrench into. I think most aftermarket ones do though. The mount that it sets on should have a round hole where the "bolt" from the leaf spring sets in to.

Sorry I don't have any pictures readily available to show you, but hopefully you understand what I'm trying to explain.

old Chevy guy · 06-17-2015, 07:37 PM

There is a hole for that bolt head and yes its round, sitting in that hole locates the spring on the rear end and keeps it from sliding in the u bolts.

**71CHEVYSHORTBED402** · 06-18-2015, 01:00 AM

I'm confused. The mount (plate) where the center bolt goes through is welded to the axle, and there's only about 3/8" clearance between the mount and axle. So unless I'm missing something, there's NO WAY to get that bolt through the mount from the bottom. Is it possible the only way is to cut the mount, slide in the bolt and then weld it back on? Doesn't seem right. Note: I'm quite sure it's stock. Stock option from what I'm hearing, but I've also heard the Custom Deluxe came with leaf springs instead of coils.

**chiefcfd** · 06-18-2015, 07:34 AM

The tie bolt does not mount to the axle perch. The bolt sits in a pocket hole. That's why you can't use a regular hex head bolt. It is used only as a locater pin. The u-bolts hold the axle. Do not weld anything.

Lees68GMC · 06-18-2015, 11:39 AM

Look you really don't need to over-think this.

Hardened, threaded steel rod (Car Quest, Auto-zone has new ones if needed) passes through every leaf in the package and when tightened down, compresses and holds the entire leaf spring package together.

Easiest details to address the hole / nut fitment issue in the welded on, axle spring perch is to buy 4 all steel Grade 8 lock nuts, Not Nylocks (install 2 on each leaf package) once tightened down they won't be going anywhere. The lock-nut that needs to fit inside the axle's welded spring perch hole won't fit as is. Using a small hand grinder, carefully round off the faces of the lock nut, a little at a time because Ideally you want that nut to fit Tight in the perch mount's hole, force fit would be best, as it's Now functioning as a "location pin" to prevent the leaf spring package from moving around. Install both 4 hole plates, U-bolts and nuts. Plop down in the man cave lawn chair, consume frosty cold one, while reflecting on a job well done.
Hope it helps.

**71CHEVYSHORTBED402** · 06-18-2015, 12:30 PM

I think I understand now. The tie-bolt simply holds the leafs together. It doesn't mount anything. The U-bolts are what mount the leafs to the axle. Thanks for all the input.

06-15-2015, 10:34 PM	#1
71CHEVYSHORTBED402 Senior Member Join Date: Feb 2009 Location: Northern Nevada Posts: 7,129	GM Frame build - Observations and question about cent bolt for leaf springs. (71 Custom Deluxe - 1/2 short fleet) The front bed brackets don't match. They're the same part, but the mounts have a short "flare/wing" on both sides at the top, only one side of the flare is shorter than the other on both pieces. One was "reversed", and they simply don't match (hardly noticeable). GM worker figures it works either way, so don't worry about it. 50/50 chance they'll match anyway...ha! The center rail on the frame under the bed is off square by about 1.25". Not sure why that is, maybe to add strength. That or it doesn't matter. Is that common? That center bolt "tie-bolt"for the leaf springs ("tie-bolt").......... the mount is notched so you can slip the head of the bolt in, right? As far as I can tell, there's no other way to get a bolt in there. Thanks for any input. __________________ Tony 71 Custom Deluxe, SWB, 2WD, 402, A/C. I developed an assm. guide "kit" for restoring it from ground up. With assys, the guide accts for 1000s details such as OEM identifications& part numbers, written in short order. 700+ images include assm, illust., charts, and points of interest. Much of the info. applies to all 67-72 GM trucks, and to a lessor degree all 67-72 GM vehicles. My build thread, and more on the guide https://67-72chevytrucks.com/vboard/...d.php?t=730025 Last edited by 71CHEVYSHORTBED402; 06-16-2015 at 11:53 AM.

06-16-2015, 11:52 AM	#2
71CHEVYSHORTBED402 Senior Member Join Date: Feb 2009 Location: Northern Nevada Posts: 7,129	Re: GM Frame build - Observations and question about cent bolt for leaf springs. ttt __________________ Tony 71 Custom Deluxe, SWB, 2WD, 402, A/C. I developed an assm. guide "kit" for restoring it from ground up. With assys, the guide accts for 1000s details such as OEM identifications& part numbers, written in short order. 700+ images include assm, illust., charts, and points of interest. Much of the info. applies to all 67-72 GM trucks, and to a lessor degree all 67-72 GM vehicles. My build thread, and more on the guide https://67-72chevytrucks.com/vboard/...d.php?t=730025

06-16-2015, 12:19 PM	#3
Lees68GMC Registered User Join Date: Jul 2013 Location: Prescott Arizona Posts: 343	Re: GM Frame build - Observations and question about cent bolt for leaf springs. Ive been looking for quite a while for new springs to lower with, maybe 2-3 inches and don't want to flip kit. My GMCs springs are only 2-1/4" wide but are stiff (spring rate). And YES that cross-member is crooked in all of them Attached Images __________________ 68 GMC SWB Vortec 5.3 98 Chevy Blazer ZR2 94 Mazda Miata, LS2 6 speed, sold "No matter what happens, nobody gets out alive"

06-16-2015, 10:51 PM	#4
71CHEVYSHORTBED402 Senior Member Join Date: Feb 2009 Location: Northern Nevada Posts: 7,129	Re: GM Frame build - Observations and question about cent bolt for leaf springs. I suspected so. Probably adds strength. That frame of yours looks familiar, only you're ahead of me. I'm just in paint removal mode. Exhaust, brakes and shocks come off later. Maybe the springs........certainly the u-Bolts for them. Safe to say the mount for the center bolt for the leafs is notched, so you can get the head of the bolt into the mount? I guess I'm looking for confirmation Really, it's the only thing that makes sense. I've been thinking about a drop myself. My brother says losing one leaf spring gives you 2", then all you need is different coil springs on the front. I've done a little homework, and at this point I'm calling BS. Unless I can hire someone to do it the right way for under $1200, it's just not worth it to me........ALREADY A MONEY PIT. Ha! __________________ Tony 71 Custom Deluxe, SWB, 2WD, 402, A/C. I developed an assm. guide "kit" for restoring it from ground up. With assys, the guide accts for 1000s details such as OEM identifications& part numbers, written in short order. 700+ images include assm, illust., charts, and points of interest. Much of the info. applies to all 67-72 GM trucks, and to a lessor degree all 67-72 GM vehicles. My build thread, and more on the guide https://67-72chevytrucks.com/vboard/...d.php?t=730025 Last edited by 71CHEVYSHORTBED402; 06-16-2015 at 11:11 PM.

06-17-2015, 10:03 AM	#5
BrianG Registered User Join Date: May 2011 Location: Oakley, Michigan Posts: 735	Re: GM Frame build - Observations and question about cent bolt for leaf springs. The bolt that goes through the center of the leaf springs has a round head, not hex shape like a normal bolt would. Sort of like an Allen type of bolt, but I don't think the original ones had a place to put an allen wrench into. I think most aftermarket ones do though. The mount that it sets on should have a round hole where the "bolt" from the leaf spring sets in to. Sorry I don't have any pictures readily available to show you, but hopefully you understand what I'm trying to explain.

06-17-2015, 07:37 PM	#6
old Chevy guy Registered User Join Date: Apr 2007 Location: Foster Rhode Island Posts: 1,176	Re: GM Frame build - Observations and question about cent bolt for leaf springs. There is a hole for that bolt head and yes its round, sitting in that hole locates the spring on the rear end and keeps it from sliding in the u bolts.

06-18-2015, 01:00 AM	#7
71CHEVYSHORTBED402 Senior Member Join Date: Feb 2009 Location: Northern Nevada Posts: 7,129	Re: GM Frame build - Observations and question about cent bolt for leaf springs. I'm confused. The mount (plate) where the center bolt goes through is welded to the axle, and there's only about 3/8" clearance between the mount and axle. So unless I'm missing something, there's NO WAY to get that bolt through the mount from the bottom. Is it possible the only way is to cut the mount, slide in the bolt and then weld it back on? Doesn't seem right. Note: I'm quite sure it's stock. Stock option from what I'm hearing, but I've also heard the Custom Deluxe came with leaf springs instead of coils. __________________ Tony 71 Custom Deluxe, SWB, 2WD, 402, A/C. I developed an assm. guide "kit" for restoring it from ground up. With assys, the guide accts for 1000s details such as OEM identifications& part numbers, written in short order. 700+ images include assm, illust., charts, and points of interest. Much of the info. applies to all 67-72 GM trucks, and to a lessor degree all 67-72 GM vehicles. My build thread, and more on the guide https://67-72chevytrucks.com/vboard/...d.php?t=730025 Last edited by 71CHEVYSHORTBED402; 06-18-2015 at 01:18 AM.

06-18-2015, 07:34 AM	#8
chiefcfd Senior Member Join Date: Oct 2010 Location: Cadiz, Ky Posts: 511	Re: GM Frame build - Observations and question about cent bolt for leaf springs. The tie bolt does not mount to the axle perch. The bolt sits in a pocket hole. That's why you can't use a regular hex head bolt. It is used only as a locater pin. The u-bolts hold the axle. Do not weld anything. __________________ 1972 Chevy LWB Roadster 1999 Chevy Silverado 2wd 2015 Chevy High Country 4x4 Crew Cab

06-18-2015, 11:39 AM	#9
Lees68GMC Registered User Join Date: Jul 2013 Location: Prescott Arizona Posts: 343	Re: GM Frame build - Observations and question about cent bolt for leaf springs. Look you really don't need to over-think this. Hardened, threaded steel rod (Car Quest, Auto-zone has new ones if needed) passes through every leaf in the package and when tightened down, compresses and holds the entire leaf spring package together. Easiest details to address the hole / nut fitment issue in the welded on, axle spring perch is to buy 4 all steel Grade 8 lock nuts, Not Nylocks (install 2 on each leaf package) once tightened down they won't be going anywhere. The lock-nut that needs to fit inside the axle's welded spring perch hole won't fit as is. Using a small hand grinder, carefully round off the faces of the lock nut, a little at a time because Ideally you want that nut to fit Tight in the perch mount's hole, force fit would be best, as it's Now functioning as a "location pin" to prevent the leaf spring package from moving around. Install both 4 hole plates, U-bolts and nuts. Plop down in the man cave lawn chair, consume frosty cold one, while reflecting on a job well done. Hope it helps. Attached Images __________________ 68 GMC SWB Vortec 5.3 98 Chevy Blazer ZR2 94 Mazda Miata, LS2 6 speed, sold "No matter what happens, nobody gets out alive" Last edited by Lees68GMC; 06-18-2015 at 11:47 AM.

06-18-2015, 12:30 PM	#10
71CHEVYSHORTBED402 Senior Member Join Date: Feb 2009 Location: Northern Nevada Posts: 7,129	Re: GM Frame build - Observations and question about cent bolt for leaf springs. I think I understand now. The tie-bolt simply holds the leafs together. It doesn't mount anything. The U-bolts are what mount the leafs to the axle. Thanks for all the input. __________________ Tony 71 Custom Deluxe, SWB, 2WD, 402, A/C. I developed an assm. guide "kit" for restoring it from ground up. With assys, the guide accts for 1000s details such as OEM identifications& part numbers, written in short order. 700+ images include assm, illust., charts, and points of interest. Much of the info. applies to all 67-72 GM trucks, and to a lessor degree all 67-72 GM vehicles. My build thread, and more on the guide https://67-72chevytrucks.com/vboard/...d.php?t=730025



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