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OEM parts bin fun: modern hubs, brake upgrades, and bolt pattern changes

12K views 79 replies 11 participants last post by  Caddylack  
#1 · (Edited)
The primary focus of this thread will be the discussion of converting the B-body to a modern hub and slip-on rotor setup using OEM parts that are affordable and easy to find. From there, the secondary focus will be the discussion of multi-piston brake calipers, larger diameter rotors, and bolt pattern changes. Let's see what we can do to freshen up an old chassis.

Things that we know:
  • All 91-96 B-body and all 85-05 RWD Astro/Safari use the same front upper control arm
  • All 85-05 RWD Astro/Safari use a front lower control arm that is virtually identical to the 9c1 lower that uses a 5/8" ball joint... the only difference is the steering stop, which may be only cosmetically different
  • All 03-05 Astro/Safari use the standard GM truck caliper of that era, which features dual 2" pistons, like the C5 Corvette
    • The dual-piston truck caliper likely requires a minimum 16" wheel
  • All 03-05 Astro/Safari use slip-on rotors in the standard 6-lug truck pattern; we are likely only interested in the RWD knuckle
  • Pre-2003 Astro/Safari used the same 5x5 bolt pattern as our cars; AWD models used a slip-on rotor, while RWD models used a spindle that is similar to ours, however with a larger bearing size
  • Based on the above, the entire 85-05 Astro/Safari RWD front end is a direct bolt-on for our cars; 6-lug conversion is just as simple as transplanting the van parts onto the b-body
    • OEM 6-lug truck rotors are available in diameters ranging from 12" to 14"
    • NOTE THAT YOU WILL LOSE ABS unless you figure out how to make it work
  • If you want to run a slip-on rotor and change your bolt pattern, the easiest way is to use the 03-05 Astro/Safari RWD knuckle; this enables you to use any modern GM hub that you like...
    • For the 6x5.5 truck pattern, use the 03-05 RWD van hub
    • For the 5x4.75 Vette pattern, use the Blazer/S-10 hub
    • If you want to run a slip-on rotor and keep 5x5, use the pre-2003 AWD van hub
  • You have 3 different options for changing your rear bolt pattern to match the front:
    • The best option is to just buy new axle shafts in the pattern of your choice; Moser is a safe bet
    • The next best option is to find a pair of axle shafts from another GM 30-spline rear and have a machine shop modify them so that they are the correct length, etc.
    • If you are on a tight budget, your other option is to get your existing axle shafts re-drilled
  • As far as rear disc conversion, you can use the backing plates and calipers from virtually any GM 8.5" rear, with the exception of vehicles that use the larger axle housing, such as the wagon, etc. The most common will be 97+ Blazer/S-10 4WD and 02+ Trailblazer, Envoy, etc.
    • Again, ABS is not taken into consideration
    • Parking brake setups will vary from vehicle to vehicle, and that is something else I have not explored; I am speaking only about physical fitment of the brakes themselves
  • Outside of GM, the most common vehicles that utilize the 5x5 pattern are Mopar products such as the Grand Cherokee, Pacifica, and mini-vans.
    • The 3rd generation Grand Cherokee uses a slip-on rotor in 5x5 pattern that is 12.9" in diameter and 2.1" in "height"; this is within about 1/10th of an inch of the height of the GM truck rotor
    • The Grand Cherokee rotor, as well as the rest of the Mopar rotors, will require slight opening of the center hole, as Mopar uses a standard size that is slightly smaller than the standard 3.06ish used on many GM vehicles
Unanswered questions:
  • What is the maximum rotor diameter for the unaltered 03-05 RWD Astro-Safari knuckle and the dual-piston truck caliper?
    • How much more can be gained by minor clearancing?
  • Will the center bore of the 03-05 RWD van knuckle need to be enlarged to accept the earlier AWD hub?
  • What kind of practical "plug" can we come up with to fill the splined hole in the AWD hub?
  • What other calipers will easily bolt to the 03-05 RWD Astro/Safari knuckle?
    • Brembos?
Why this stuff is relevant and important:
  • The B platform is objectively outdated (obviously)
  • Aftermarket support for our cars is dwindling
    • This could be a motivation for switching bolt patterns
  • Our cars are becoming more and more rare, while other GM products such as trucks and vans are still a dime a dozen in any junkyard; in many cases upgrading to "parts bin" stuff will be cheaper and easier than sourcing "genuine" B-body parts
 
#2 ·
The 6-lug swap is confirmed 100% bolt-on.
You can literally just take the entire front suspension from a 2003-2005 RWD Astro/Safari and put it on the B-body.
The upper control arm is the same part number between all years of RWD Astro/Safari and b-body.
The lower control arm on the RWD Astro/Safari is interchangeable with the 9C1 lower with the 5/8" ball joint.

Still need to confirm if the larger 13" rotor will work, but that's really the only issue. Just eyeballing, I don't think track width will be a problem. The 6-lug hub is very compact. I've included some pics below of a 2005 Safari RWD. ABS has not been investigated at all, nor do I intend to do so. The Astro uses a 16" wheel, so this may be the minimum wheel size needed for this swap.

Now, if a person wanted to keep the 5x5 pattern but change to the modular hubs, dual-piston calipers, and larger rotors …
That procedure is almost bolt-on, but not quite. I think there may be a slight difference in the size of the opening on the knuckle. The opening on the RWD knuckle may be just slightly too small to slide the AWD hub into. If so, it will just be a matter of stopping by a machine shop. The 12.9" Jeep rotor will also require slight enlarging of the center hole, but other than that, it will fit. The last thing I need to verify on that end of things is whether the knuckle will need to be clearanced at all for the larger rotor. If we are lucky, it will clear without modification.

As soon as I have one of these setups on the road, I will be sure to post a new thread on the topic.
This gets me wondering about the front suspension of a '95-'02 Astrafari …
 
#3 ·
I'm assuming you mean 1985 and not 1995, but there really isn't much that changes over the years in those vans. It's generally just a matter of RWD vs AWD, bolt pattern, etc. Most stuff is interchangeable physically.
 
#4 ·
Let's see what we can do to freshen up an old chassis.
Remove entire front suspension and crossmember and replace with complete Panther platform stuff? Aluminum control arms, rack and pinion, etc etc. NIce to see stuff that isn't from the 1970s... no idea if this would work on our chassis, but it looks good on trucks.

 
#5 · (Edited)
Remove entire front suspension and crossmember and replace with complete Panther platform stuff? Aluminum control arms, rack and pinion, etc etc. NIce to see stuff that isn't from the 1970s...
The 2003+ Panther platform is awesome. A full frame with MacPherson struts and an axle-mounted sway bar in the rear sounds like fun. Plus a good transmission. The only thing wrong with them was the lack of power from the factory, but obviously the aftermarket is huge.

Some day I would love to build a 2003+ Towncar with a roots blower.
 
#6 ·
As bolt in as that panther front suspension is, I swear somebody in a design meeting asked how wide the frame rails should be and some engineer went home and measured his project truck.

-Brian
 
#9 ·
If I remember correctly the Vic out preformed the Caprice in 92 but when the LT1 came out the Vic never quite caught up with 235HP and 3.55 axle.

In my case 96 Vic 210HP 3.27 axle VS 94 Caprice 260HP 3.73 axle.:)

91SS are you helping the Vic crowd with spring info now?
 
#16 · (Edited)
Look up front suspension on rockauto for a 2003+ Vic.

They use MacPherson struts that mount to a strut tower up top and to the lower control arm at the bottom.
 
#17 ·
The car has an upper control arm !!!
Image



Just because there is a coil mounted on a shock that doesnt make it a Mac strut.
Macpherson strut suspension , the strut is the upper susp mounting point- pivot.

Research what a Macpherson Strut susp actually is and get back to us .
 
#73 ·
View attachment 198116

MacPherson strut systems still use a single control arm, located at the bottom of the assembly, but it’s a far cry from the complex, four- and five-point mounted control arms that adorn wishbone and multi-link systems. MacPherson strut systems provide simple steering pivots at the wheel hub, allowing the easy connection of steering systems via small metal bars known as tie rods.

My misinformation about "MacPherson" was the result of something I read years ago about the Trailblazer being the first SUV to use a "MacPherson strut" suspension. I couldn't find the source when I searched before, but I just happened to stumble across it just now.

It was the DJM website. Yes, that's right. One of the most prominent suspension companies in the country (especially for the TBSS) apparently does not know what a MacPherson suspension is.

Copy and pasted:

"The trailblazer was the first design to use a “McPherson Strut” type front end, contributing to the high performance of this SUV!"

Link: DJM2301-2/4

Actual pictures of the GMT360 front end:

Image

Image
 
#18 ·
198116


MacPherson strut systems still use a single control arm, located at the bottom of the assembly, but it’s a far cry from the complex, four- and five-point mounted control arms that adorn wishbone and multi-link systems. MacPherson strut systems provide simple steering pivots at the wheel hub, allowing the easy connection of steering systems via small metal bars known as tie rods.
 
#24 ·
Or the Modified MacPherson Strut like in Mustangs. Strut configuration, but conventional coil spring on lower arm instead of on the strut itself.

Z09B4U - You peaking on the crownvic.net site ;)
The 08 btw, is 250hp with 297 ft-lbs, and almost makes me a believer there IS a 'cop chip' lol
 
#20 · (Edited)
If I am technically misusing the term "MacPherson", then I apologize.

It seems the term "MacPherson" doesn't even refer to the actual strut itself, but rather the way that it mounts on the vehicle, yes? So, if the strut were off of the vehicle in a cardboard box, there would be zero difference.

What I meant to say was that the 03+ Panther platform uses a "ready-strut", or whatever you want to call it, where the entire shock/spring/mount assembly is all one unit.
 
#21 ·
Honestly it may be faster to just put the whole panther frame and chassis under the B-body body. Then you're just lining up or making body mount points, and it's not like the B-body frame is an incredibly rigid piece to begin with.
 
#23 ·
While we're talking body swaps and similar chassis dimensions... a Tesla sedan is about the same wheelbase as a B body. Just throwing that out there. Let's convince Rich Rebuilds to do a Tesla Roadmaster Wagon.
 
#28 · (Edited)
We need a bench racing ,half baked , never, gonna happen , forum.

I'd go the other way, gas powered tesla or chevy volt .
We have a couple of Gibbs 358 SB2s sitting in crates here.
Licence plate REVOLT
Will it happen ?? No but neither will most of the half baked ideas on the forum.

Edit, sorry to derail your thread.
 
#31 ·
We need a bench racing ,half baked , never, gonna happen , forum.
Is this really necessary? I started my own thread to avoid confrontation.

Not to mention, you're the guy who had the half-baked idea to put an LS7 in a station wagon just so you could say you did.
 
#33 ·
Pretty sure there is a YouTube channel building an LS swapped tesla.

-Brian
 
#36 ·
Having the 91 outfitted with SS springs, bilstein shocks, bigger sway bars, SS rims and tires, it's no where near as zippy and crisp as the 08 cvpi. The 08 has a revised front suspension (02 and older is very similar to the caprice), has a full ridged 'boxed' frame and the rear uses a watts linkage set up and stiffer springs all around. It's a very solid feeling car.
 
#38 ·
Thank you!
As usual, I was missing some part. How does the 91 (outfitted as you describe) feel compared to the 94-96 Impala? Do those things bring it equal to the Impala as one would expect? I know the Impala and 9C1 used a thicker frame steel, but I would think that is negligible?
 
#45 ·
Wow... So the Panther has a track width difference of nearly 3" front to rear.
 
#48 ·
A search of a Vic site would probably be best. As I have a factory bar system specific to my year and oil cooling package (changes the shape of the front) I have not paid attention.

This is the go to site for panther specifications and has a page on the rear bars.



F3AZ-5A772-A
21.0
93-00
Handling Package. Type S/H
Obsolete
YW7Z-5A772-CA
21.0
01-
Handling Package (Used on 2003 & 2004 mercury marauders too)
$56.65
 
#50 ·
I feel like I would buy a coilover setup before I would attempt to splice in the Ford stuff.

Definitely more interested in the GM parts bin where stuff will directly bolt on. There are surely many combinations of parts out there that fit that we have not yet discovered.
 
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#51 ·
I would definitely consider the GM parts bin. I'd get the Astro awd knuckle and use the slip on rotor just to use the bigger lower ball joint. But I'm curious about something. I understand the purpose behind the bigger ball joint for the police and taxi vehicle but what about the civilian vehicle. Does it actually improve anything on the b body besides not breaking. I'm curious about this.
 
#52 ·
Well, "not breaking" is one way to put it. 😂

I'm not sure if it has any impact on cornering performance or not.
 
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#54 ·
I recall they somewhere after the fact discovered the 9/16 ones were under tightened which was the real problem. They'd loosen some then snap because of the play. I don't think the prior body style ever had the 5/8 ones.
 
#55 ·
If millions of older vehicles surviving 100 000 of miles is not good enough and you do not want to inspect your suspension regularly maybe skip over 5/8 and go to 11/16.

Bigger is better right?


Or get aftermarket tube arms because the stamped steel OEM style might flex.
 
#59 ·
If millions of older vehicles surviving 100 000 of miles is not good enough and you do not want to inspect your suspension regularly maybe skip over 5/8 and go to 11/16.

Bigger is better right?


Or get aftermarket tube arms because the stamped steel OEM style might flex.
I'm actually already planning on upgrading my front control arms to tubular control arms
 
#56 ·
We should just upgrade to ball joints meant for a tractor or combine of some sort.
 
#60 ·
Half-baked thoughts:

We know that the 2nd gen f-body shares numerous front end parts with our cars. We also know that the frame rail spacing is the same, as evidenced by sway bar interchangeability. The 73-77 a-body is also relevant to our interests here.

Aftermarket support for the f-body is much greater than for our cars. There are rack & pinion conversion kits, and there are also aftermarket bolt-in subframes. Boy would it be nice if we discovered that these subframes will fit our cars in some capacity.
 
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#63 ·
Oh I definitely understand. My thing is that I'm very late to the party on my car so it is basically a crash course to learn and catch up with you gentlemen. So far the only thing I have seen that is new is the I believe they called it a torque rod from speedtech performance. It's basically just like what the f bodies got only this one looks better but may require a aftermarket rear end. Figure I mention that in case anyone was interested