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73-87 Chevy _ GMC Trucks => Brakes, Frame, Steering & Suspension => Brakes and Braking Systems => Topic started by: tusk on November 06, 2008, 02:08:35 pm
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i may have put this in the wrong section,but i was wondering what have ya'll been doing as far as rear disc conversions,i was wondering why i couldnt get some impala rear rotors and use them,as far as the calipers,in the 4x4 world,we have been using 1/2 front calipers on homemade brackets, with 3/4 4x4 rotors,any ideas or pics,
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well ifeel like a goof,wheni did the search on here i came up empty handed,i typed in rear bake conversion,no reason there was no matches ::)
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There are a few companies making these conversions CPP, SSBC. But if you want to make your own you can use Impalla SS rear rotors and calipers and make you own bracket.
http://www.73-87.com/7387garage/chassis_suspension/reardisc.htm
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I just called my guy at the parts store and rear rotors are 28.00,but the rear calipers are 62.00 ea,unloaded,wow,i will probably use the ss rotors,and make my own brackets and use the 1/2 ton caliper that can be bought for 25.00 loaded,when i start on this part of the project i'll post up some pics
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The downfall to using truck calipers is there is no parking brake..
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There are a few companies making these conversions CPP, SSBC. But if you want to make your own you can use Impalla SS rear rotors and calipers and make you own bracket.
http://www.73-87.com/7387garage/chassis_suspension/reardisc.htm
Hey now! If I go out to my car, and find my brakes gone, I'll no where to look for them :o ;D :P
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Chris, Going with the Impala calipers on home-made brackets...there wouldn't be any parking brake either.
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If you see the writeup I posted Mike has the bracket dimensions for 80-85 Cadillac Seville calipers with P-brakes.
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The downfall to using truck calipers is there is no parking brake..
who needs a stinking parking brake ;D,seriously though,Ive been driving a little of 20 years and every car/truck that was a automatic,Ive never used the parking brake,has the impala got the inside the rotor hat parking brake system,like the explorers,that would be a neat conversion,after doing a little research Latinate,I'm going to order a set of the speedway rotors and hats,make my own brackets and use the metric front gm calipers,just hope it will be worth it over the drums but i doubt it,if it goes according to plan without the m/c or p/v i should have around 200.00 in the conversion
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Chris, I misunderstood the way you worded the sentence that you were thinking of using Impala calipers also, but posted the link for help with making the bracket on the axle housing, Sorry.
Yes Tusk, the Impala has a drum inside the rotor, the backing plate has the "regular" GM car axle bolt pattern, but uses the 5" wheel bolt pattern like the 2wd trucks. Lorne
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NO problem I read it again and realized it was confusing. You could modifiy the Axle tube to take the impala backing :D
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That is something I had questioned before, me & someone on here pondered that...but I never went any farther. I should be able to check on that. I have complete set of Impala brakes on a shelf & the ends of the axle tubes I cut off the 8.5 rear when I made the 9" should still be in the scrap bin. Does anyone know (or can check) the axle set-out (distance from the face of the backing plate flange to the face of the wheel flange on the axle) on the 8.5 & 12 bolt truck rear? The Impala is 2 3/4", It would be nice if the truck was more, it could allow for a spacer to be machined to fill in the recess in the back backing plate for the flange to seat. I'm also concerned about the "snout" sticking out where the bearing goes...they made the bolt pattern bigger on the truck, I'm assuming to have clearance around a bigger bearing? There may not be enough clearance around the parking brake set-up to allow for it. Over the next day or Two I'll check it out & report back, unless someone has already done so, Speak up. Lorne
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Guys, I did some checking on the Impala backing plate/disc brake caliper bracket this evening. At a glance, it looks more positive than I had expected. The back side has a large flat area, so the bigger truck flange isn't a problem. The parking brake workings are outward far enough to clear. The only thing that is a little questionable is a groove/step area that will likely be close to where the truck mounting bolts will be. This may require a plate on the inside to have the bolts sit on to be flat. The center hole will need opened up for sure. Another nice thing is both calipers are on the back of the axle (not one in front like many set-ups).
Does anyone have a truck rear with the wheel off to measure the axle set-out? If it's 2 3/4" like the cars...this could be interesting.
On a side note, especially if your truck has a 2 something gear, non-posi rear...a complete Impala rear could be adapted, the width is very close, wheel bolt pattern is the same. All you would need is some spring perches & shock brackets to end up with a 3.08-3.42 gear posi rear with good disc set-up (aluminum PBR calipers with vented rotors) just a thought?
If I was a guy in the planning stages for rear discs on my truck, I would defiantly research the Impala backing plate plan some more! Have Fun! Lorne
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I have one out of a truck but I have to get it out of the back of my crew cab. I can get you any measrement you want tomorrow evening.
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Sorry to dig this one out of the cemetery but I have been looking for an alternate way of putting disc brakes and a posi unit on my C10 without spending too much $$$$ on it. Can any one tell me the measurements of an Impala rear end vs. the 8.5 12 bolt in my C10? Other then the spring pads and shock mounts what are the other down fall to making this work?? What about the section where the driveshaft mounts to the diff. will the factory C-10 u-joints sit in? If this will fit, this is more economical for me to use instead of having my rear end rebuilt to a posi and purchasing the brake conversion kit. Haulin It, I saw you were looking into this. Did you ever have any luck? Any help would be great. Thank Guys
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As Lorne pointed out, the overal width is close enough for the swap. I don't know what type U-joint it would use, but that would be a minor issue to find out, just look it up.
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One other question, when I mock it up, can you tell me at which loction the spring pads should be in? I mean where should they be in relations to the pumkin for the driveline angle? If I can figure that out then everything else would fall in place. I picked up a complete unit out of 96 Impala for $225.00 and the car only had 49,000 miles on it. I poped the cover off and everything looks great inside it.
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Not sure I am following you here. Are you wanting to know where the spring pads should be located?
I would use the factory one and measure off of it.
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Yes, I need to know at what angle should I weld the spring pads (in relation to the tansmission output shaft angle) on the Imapla Differential? I want to make sure I have the correct drive angle so my driveshaft does not bind up. Also if I do have to change the rear u-joints, how would I go about doing that if divehaft will still need the original style u-joints and the Impala diff will need what "it" calls for? Will I be able to switch out the Pinion Yoke on the Impala diff to the one from my original truck diff to just use the original u-joints? Are the splines the same on the Pinion gear to mount the yoke? Thanks
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You need to set the angle to match that of the output of the transmission. Should be around 3-5 degrees up.
I would see what u-joint it takes and see if the hybrid joint will work, or just have your driveshaft end changed to use the Impala joint.
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Thanks Capt.