72 K5 or K10 rear u bolt dimensions - The 1947 - Present Chevrolet & GMC Truck Message Board Network

jmking9 · 11-04-2021, 12:37 PM

I'm needing the dimensions of a stock u bolt that would have been on a 1972 4wd Blazer (or K10 I think) I need to know if they were 9/16 or 5/8. And also, what length they were. All of the stock pieces from my 72 K5 are long gone. I'm ordering new stock height spring, and trying to peice all of the stock components for the rear suspension. I've got everything tracked down except for u bolts. Any help would be greatly appreciated!
This picture is for reference, and as far as I know what my setup should look like.

**kwmech** · 11-04-2021, 01:39 PM

Couple of ways you can go here. You can go stock---square bolt pointing down or round bolt facing up. Do you still have the u bolt retaining plate that sits on top of the spring and the lower plate that the nuts tighten on? (square)

jmking9 · 11-04-2021, 02:35 PM

I bought the lower plates that go under the axle from a friend. He is shipping them to me, but I don't have them in hand yet. I ordered the upper plates that sit on top this morning. I'm getting springs from General Spring in KC. They can make the u bolts, but I have to tell them the shape, diameter, width, and length. I know they are square shape, and I know they are 2.5 wide. I'm just not sure if they are 9/16 like the front, or something different. And I'm not sure how long they need to be. If I had the new springs, and the plates in hand, I could measure and know. I was just hoping to get them ordered in advance so I would have everything to put them in without having to wait on the u bolts.

**kwmech** · 11-04-2021, 06:43 PM

5/8'' was the factory diameter. Takes a 15/16 socket. Measurement should be around 7-8'' long. Diameter of the axle tube (3'') plus spring pack thickness (2.5-3'') plus height of nut 1''. Or just wait until you get the plates, dry fit everything with a tape measure to confirm

jmking9 · 11-04-2021, 08:46 PM

Thanks kwmech!
The brackets that go under the axle came today. When you stick a 5/8 bolt in the holes, they seem pretty big. Does this look normal? Do I have the correct plates?

jmking9 · 11-04-2021, 09:00 PM

Pics

**kwmech** · 11-05-2021, 12:27 AM

Correct plates--rusted holes. The bolts will come with a triple thick flat washer. They'll torque to 150#. the plates you got had a tendency to break through the center. GM went to a stamped steel plate a few years later that can be substituted if need be

11-04-2021, 12:37 PM	#1
jmking9 Registered User Join Date: Sep 2006 Location: Riverton KS Posts: 832	72 K5 or K10 rear u bolt dimensions I'm needing the dimensions of a stock u bolt that would have been on a 1972 4wd Blazer (or K10 I think) I need to know if they were 9/16 or 5/8. And also, what length they were. All of the stock pieces from my 72 K5 are long gone. I'm ordering new stock height spring, and trying to peice all of the stock components for the rear suspension. I've got everything tracked down except for u bolts. Any help would be greatly appreciated! This picture is for reference, and as far as I know what my setup should look like. Attached Images __________________ 1970 SWB Build

11-04-2021, 01:39 PM	#2
kwmech Senior Member Join Date: Mar 2003 Location: Colfax-California Posts: 8,630	Re: 72 K5 or K10 rear u bolt dimensions Couple of ways you can go here. You can go stock---square bolt pointing down or round bolt facing up. Do you still have the u bolt retaining plate that sits on top of the spring and the lower plate that the nuts tighten on? (square)

11-04-2021, 02:35 PM	#3
jmking9 Registered User Join Date: Sep 2006 Location: Riverton KS Posts: 832	Re: 72 K5 or K10 rear u bolt dimensions I bought the lower plates that go under the axle from a friend. He is shipping them to me, but I don't have them in hand yet. I ordered the upper plates that sit on top this morning. I'm getting springs from General Spring in KC. They can make the u bolts, but I have to tell them the shape, diameter, width, and length. I know they are square shape, and I know they are 2.5 wide. I'm just not sure if they are 9/16 like the front, or something different. And I'm not sure how long they need to be. If I had the new springs, and the plates in hand, I could measure and know. I was just hoping to get them ordered in advance so I would have everything to put them in without having to wait on the u bolts. __________________ 1970 SWB Build

11-04-2021, 06:43 PM	#4
kwmech Senior Member Join Date: Mar 2003 Location: Colfax-California Posts: 8,630	Re: 72 K5 or K10 rear u bolt dimensions 5/8'' was the factory diameter. Takes a 15/16 socket. Measurement should be around 7-8'' long. Diameter of the axle tube (3'') plus spring pack thickness (2.5-3'') plus height of nut 1''. Or just wait until you get the plates, dry fit everything with a tape measure to confirm

11-04-2021, 08:46 PM	#5
jmking9 Registered User Join Date: Sep 2006 Location: Riverton KS Posts: 832	Re: 72 K5 or K10 rear u bolt dimensions Thanks kwmech! The brackets that go under the axle came today. When you stick a 5/8 bolt in the holes, they seem pretty big. Does this look normal? Do I have the correct plates? __________________ 1970 SWB Build

11-04-2021, 09:00 PM	#6
jmking9 Registered User Join Date: Sep 2006 Location: Riverton KS Posts: 832	Re: 72 K5 or K10 rear u bolt dimensions Pics Attached Images __________________ 1970 SWB Build

11-05-2021, 12:27 AM	#7
kwmech Senior Member Join Date: Mar 2003 Location: Colfax-California Posts: 8,630	Re: 72 K5 or K10 rear u bolt dimensions Correct plates--rusted holes. The bolts will come with a triple thick flat washer. They'll torque to 150#. the plates you got had a tendency to break through the center. GM went to a stamped steel plate a few years later that can be substituted if need be

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