trailing arm brackets - The 1947 - Present Chevrolet & GMC Truck Message Board Network

james colbert · 11-15-2009, 10:49 PM

Guess that the best way title it. Does anyone make a set of adjustable trailing arm brackets? My truck is on a 67 frame and looking at building a set if I cant buy them. Something to control pinion angle, change bar angle?

**Captainfab** · 11-16-2009, 12:36 AM

I don't think anyone makes them.
Board member and Moderator here on the Racing and high performance forum, Super73 made a set for his '63. I know it is posted here somewhere, but I can't seem to find the thread. You might try sending him a PM

Super73 · 11-16-2009, 04:17 AM

Correct, I made them from a piece of 2x4 box steel. Drill the holes and then cut 1 side off. Have fun drilling the rivets

It will not help you adjust pinion angle, that you need to do with a shim, but it will allow you to get more squat or antisquat in the chassis.

james colbert · 11-16-2009, 08:47 AM

Thats what I needed to know, thanks guys

djracer · 11-16-2009, 10:21 AM

Quote:

Originally Posted by Super73

Correct, I made them from a piece of 2x4 box steel. Drill the holes and then cut 1 side off. Have fun drilling the rivets

It will not help you adjust pinion angle, that you need to do with a shim, but it will allow you to get more squat or antisquat in the chassis.

It seems like it would have to adjust pinion angle a little. I know the arms are long but I would still think you would get a degree or two from top to bottom holes.

Super73 · 11-16-2009, 03:36 PM

Yes, it does adjust pinion angle, but, there is more of a chassis adjustment than pinion angle. For every 1" of adjustment on the LCA hole, there is about 1.1* of adjustment on the pinion. But that 1" of chassis adjustment (that's what I'm calling it for lack of a better term) you could see 5-10% of squat/anti-squat change depending on where you center of gravity height is.

I would not adjust the height of the front hole to compensate for pinion angle. It will open up another can of worms. They should be set up seperately to obtain an optimaly set combo. Hope that makes sense.

dave brode · 11-16-2009, 04:52 PM

Will commonly available wedges work between the rear and arms?

Dave

Super73 · 11-16-2009, 06:46 PM

unfortunately not with out slight modifacation. Standard leaf rears have 2 u-bolts holding the rear to the leafs. Ours use a thick single U bolt. I bought standard angle's and then cut some of the center out of the front and back to acomadate the large single U-bolt.

Keep this in mind, if the joints in the front had zero deflection, squat will promote negative pinion angle, and antisquat will promote positive pinion angle. Knowing what the suspension is doing under load allows you to set it up correctly.

IMO (until proven wrong) pinion angle has nothing to do with traction (bite) but rather helps with efficiancy under full load (putting all your power down). The goal is to get pinion angle to a perfect zero degrees under full load for best acceleration. Where your going to see the biggest change on pinion angle is at the starting line. This is why a proper pinion angle shows a better 60'

11-15-2009, 10:49 PM	#1
james colbert Registered User Join Date: Oct 2009 Location: cabot ar Posts: 19	trailing arm brackets Guess that the best way title it. Does anyone make a set of adjustable trailing arm brackets? My truck is on a 67 frame and looking at building a set if I cant buy them. Something to control pinion angle, change bar angle?

11-16-2009, 12:36 AM	#2
Captainfab 60-66 Nut Join Date: Mar 2007 Location: Coeur d'Alene, Idaho Posts: 23,252	Re: trailing arm brackets I don't think anyone makes them. Board member and Moderator here on the Racing and high performance forum, Super73 made a set for his '63. I know it is posted here somewhere, but I can't seem to find the thread. You might try sending him a PM __________________ Power Steering Box Adapter Plates For Sale HERE Power Brake Booster Adapter Brackets For Sale '63-'66 HERE and '67-'72 HERE and '60-'62 HERE and "60-'62 with clutch HERE Rear Disc Brake Brackets For Sale. Impala SS calipers HERE Camaro Calipers HERE D52 Calipers HERE 6 Lug HERE Hydroboost Mounting Plates HERE

11-16-2009, 04:17 AM	#3
Super73 Registered User Join Date: Nov 2007 Location: Bay Area, Ca Posts: 2,841	Re: trailing arm brackets Correct, I made them from a piece of 2x4 box steel. Drill the holes and then cut 1 side off. Have fun drilling the rivets It will not help you adjust pinion angle, that you need to do with a shim, but it will allow you to get more squat or antisquat in the chassis. __________________ ------Motor---------------Bottle 60'---1.53---------------1.41 1/8---6.58 @ 105.92----5.87 @ 118.41 1/4---10.38 @ 126.97----9.24 @ 142.49 Last edited by Super73; 11-16-2009 at 04:18 AM.

11-16-2009, 08:47 AM	#4
james colbert Registered User Join Date: Oct 2009 Location: cabot ar Posts: 19	Re: trailing arm brackets Thats what I needed to know, thanks guys

11-16-2009, 03:36 PM	#6
Super73 Registered User Join Date: Nov 2007 Location: Bay Area, Ca Posts: 2,841	Re: trailing arm brackets Yes, it does adjust pinion angle, but, there is more of a chassis adjustment than pinion angle. For every 1" of adjustment on the LCA hole, there is about 1.1* of adjustment on the pinion. But that 1" of chassis adjustment (that's what I'm calling it for lack of a better term) you could see 5-10% of squat/anti-squat change depending on where you center of gravity height is. I would not adjust the height of the front hole to compensate for pinion angle. It will open up another can of worms. They should be set up seperately to obtain an optimaly set combo. Hope that makes sense. __________________ ------Motor---------------Bottle 60'---1.53---------------1.41 1/8---6.58 @ 105.92----5.87 @ 118.41 1/4---10.38 @ 126.97----9.24 @ 142.49 Last edited by Super73; 11-16-2009 at 03:37 PM.

11-16-2009, 04:52 PM	#7
dave brode Registered User Join Date: Jun 2008 Location: Frostburg, Maryland Posts: 38	Re: trailing arm brackets Will commonly available wedges work between the rear and arms? Dave __________________ '71 C-10 medium bed. Pump gas 454" +.030", stock valved 049s, dana 60 w/410s. 12.25 at 108.

11-16-2009, 06:46 PM	#8
Super73 Registered User Join Date: Nov 2007 Location: Bay Area, Ca Posts: 2,841	Re: trailing arm brackets unfortunately not with out slight modifacation. Standard leaf rears have 2 u-bolts holding the rear to the leafs. Ours use a thick single U bolt. I bought standard angle's and then cut some of the center out of the front and back to acomadate the large single U-bolt. Keep this in mind, if the joints in the front had zero deflection, squat will promote negative pinion angle, and antisquat will promote positive pinion angle. Knowing what the suspension is doing under load allows you to set it up correctly. IMO (until proven wrong) pinion angle has nothing to do with traction (bite) but rather helps with efficiancy under full load (putting all your power down). The goal is to get pinion angle to a perfect zero degrees under full load for best acceleration. Where your going to see the biggest change on pinion angle is at the starting line. This is why a proper pinion angle shows a better 60' __________________ ------Motor---------------Bottle 60'---1.53---------------1.41 1/8---6.58 @ 105.92----5.87 @ 118.41 1/4---10.38 @ 126.97----9.24 @ 142.49

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