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Apr 26th, 2026 | | AD Chevy Trucks  Over 6,000 pictures Brad Allen has an awesome collection of Chevrolet factory pictures that he has set up from film strips. Check them out!
Lots of work on Brad's part ... pure enjoyment (and references) for you!
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| | | | Joined: Apr 2005 Posts: 2,832 'Bolter | | 'Bolter Joined: Apr 2005 Posts: 2,832 | I guess we have done just about every open rear into an AD that exists but done a Trailblazer into a 50 3100 that was a first. Track width is perfect and has a CLOSE to 6 on 5.5" lug pattern. It's metric so early wheels won't fit but one can drill the old pattern putting the inch holes halfway between the millimeter holes. The disc rotor is also the E-brake drum so the AD E-brake cable is easy to hook up. The one pictured has been drilled 5 on 4.75 to match the rotors on the MII ifs and has 17" wheels to clear the calipers. Tires are 255/85/R17 and look good on an AD. Yes, it has the "potato digger" stance right now but that will be remedied. Poor picture under bad light but gives an idea of the "look". [img]https://i.postimg.cc/ctR7cs9L/IMG-5085.jpg[/img]Trailblazer track width clears both fender lip and frame rail: [img]https://i.postimg.cc/DWGczdrG/IMG-5086.jpg[/img]Re-drilled Trailblazer rotor is way bigger than MII fronts so will definitely need a proportioning valve: [img]https://i.postimg.cc/xk9dk9HP/IMG-5087.jpg[/img]
Last edited by coilover; 06/25/2020 1:22 PM.
Evan
| | | | | Joined: Mar 2008 Posts: 1,775 'Bolter | | 'Bolter Joined: Mar 2008 Posts: 1,775 | Is that a 8" rear or the 8.6" rearend? Who did the drilling? Is it a jig? I`m considering using the rear out of my Trailblazer that has taken residency in my yard. My hangup is the bolt pattern and not having a posi. | | | | | Joined: Apr 2005 Posts: 2,832 'Bolter | | 'Bolter Joined: Apr 2005 Posts: 2,832 | It came out of a short wheelbase 4200 i6 so it is an 8". We do our own drilling using jigs made from axle end lug bolt flanges. Axle is cut off flush with flange and then an OVERSIZE hole is bored out in the center of the flange. Adapter rings are made to give a tight fit onto the drum/rotor pilot on the axle, the jig is clamped into place, and then a smooth sided center drill that snugly fits the original lug hole is used to make a starter hole. This is followed by the correct drill for the lug. For a one time use you would not need to set up for adapter rings. We have a mill and an index table but the jig takes almost no set up time and is very accurate. On my 37 Buick which used lug bolts instead of studs I re-drilled the lug pattern right on the car (it was kind of an emergency). Photos: Center hole in wheel is way bigger than axle pilot: [img]https://i.postimg.cc/2qxxT1cn/drilling-hubs-002.jpg[/img]Adapter ring is turned out of WOOD (hey it's MY car): [img]https://i.postimg.cc/NL2Hjy6b/drilling-hubs-003.jpg[/img]Custom made transfer punch that fit holes in brake drum was made to mark for holes: [img]https://i.postimg.cc/SXzhMpg0/drilling-hubs-004.jpg[/img]Finished, Original bolts are orange, new studs are white. Now any 5 on 5 wheel fits. [img]https://i.postimg.cc/k63BVsFc/drilling-hubs-001.jpg[/img]
Evan
| | | | | Joined: Jun 2011 Posts: 5,096 Crusing in the Passing Lane | | Crusing in the Passing Lane Joined: Jun 2011 Posts: 5,096 | Great to know, I wondered if Trailblazer/GMC equal would work.
Coilover, how do you center the wheel in use, by lug bolts only or with a metal sleeve?
Ed
'37 GMC T-18 w/ DD 4-53T, RTO-610, 6231 aux., '95 GMC running gear, full disc brakes, power steering, 22.5 wheels and tires.
'47 GMC 1 ton w/ 302, NP-540, 4wd, full width Blazer front axle.
'54 GMC 630 w/ 503 gasser, 5 speed, ex fire truck, shortened WB 4', install 8' bed.
'55 GMC 370 w/270, 420 4 speed, grain, dump bed truck from ND. Works OK.
| | | | | Joined: Apr 2005 Posts: 2,832 'Bolter | | 'Bolter Joined: Apr 2005 Posts: 2,832 | Ed.
Its better for the wheel to be hub centric rather than lug nut centric but my old Buick has been fine for 12 years with wheels being centered by the lugs, and it is a HEAVY car. Also not a Saturday night cruiser or parade car but has been border to border and coast to coast. Original wheels have 10 holes, 5 lug bolt holes and 5 holes for the indexing prong which is a PITA holding wheel on prong while starting lug BOLTS. Even worse on drivers side which uses LH thread. Of course age has increased my wuss factor expotentially. With studs and no prong any 5 on 5 wheel with correct offset and which clears the front brake caliper can be used.
Evan
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