> How To Swap an 8.8-Inch Ford Rear into a GM G-Body<
#1
12-05-2014, 06:20 PM
> How To Swap an 8.8-Inch Ford Rear into a GM G-Body<
How To Swap an 8.8-Inch Ford Rear into a GM G-Body
Hot Rod
Scott Parker, Manufacturer, Dave Rushen2 days ago
For years, the supply of G-body 8.5-inch rearends seemed it would never dry up, making them a cost- effective and easy replacement for the maligned 7.5- or 7.625-inch 10-bolt. Now those days are behind us, so your choices are: continue breaking 10-bolt ring gears or pony up some serious coin for an aftermarket housing. There is a road less traveled, though, that involves salvaging a Ford 8.8-inch rear from a junkyard.
Before we walk you through the process of swapping an 8.8-inch rear into a G-body, let's start with a little background. The Olds 442, Buick Grand National, and later T-types (as well as Turbo T Limited) were the only G-bodies that came from the factory with an 8.5-inch 10-bolt rearend (RPO GU6 and GT4). Even the mighty Chevy Monte Carlo SS was relegated to the smaller ring gear. Though some impressive feats have been pulled off with the diminutive 7.5, more often than not, it is a source of a failure with sticky tires or numerically higher ratio gears—even on the road course.
Since no other rear matches the G-body's suspension and mounting points, an aftermarket housing (12-bolt, 9-inch, or S60) is the only bolt-in rearend. But with a little elbow grease, you can make the Ford 8.8-inch rear a viable solution for the G-body at a fraction of the cost. Step one is to locate a solid rearend. Thankfully, 8.8s are plentiful in the boneyard, and often you can pick one up cheaply from a Mustang buddy who is swapping to a 9-inch. Keep in mind, though, that width, gear ratio, differential type, brakes, and bolt pattern will vary per application. Here is an incomplete list of 8.8-inch rears to choose from:
Model YearModelAxle WidthBrakesBolt Pattern1986–1993Mustang V-858.75Drum4x4.251990–1997Ranger58.750Drum5x4.501994–2003Explorer59.750Drum or disc5x4.501990–1995Aerostar59.750Drum5x4.501979-2002Crown Victoria62.80Drum or disc5x4.501987–1988Thunderbird Turbo Coupe61.50Disc4x4.251984–1992Lincoln Mark VII61.50Disc5x4.501994–1998Mustang60.250Disc5x4.501999–2004Mustang61.6250Disc5x4.50
Unless you plan to cut and narrow the rear, the Fox-body rear is by far the best choice of the bunch, since it is the closest to the factory G-body width (57.25-inches). Though the Ranger rearend is the same width and comes with 5-lug axles, as well as 3.73:1 or 4.11:1 gears, you will want to steer clear. The differential is offset in the Ranger, making driveshaft alignment impossible with a 200-4R, TH350, T56, or other GM trans of your choosing. In addition, most have an open differential, which is no good for a performance application. The Mustang's Traction-Lok is a clutch-based limited-slip differential that is rebuildable and sturdy. However, hardcore drag racers may want a spool, while road racers can use the FRPP carbon rebuild kit or go with a gear-based limited slip (such as a Truetrac). Unlike the smaller 10-bolts, there are plenty of aftermarket options for the 8.8-inch from the differential to gear ratios, axles, and C-clip eliminators. And let's face it; if you break the ring gear in a properly built 8.8, you deserve a medal.
Before you lay down some dough on an 8.8, it's important to make a game plan. At the very least, retrofitting the rearend in a G-body will require: 1) a new driveshaft to match the flat-flange-style pinion yoke, 2) cutting off the old spring perches and welding on a G-body set, 3) Mustang adjustable upper control arms with conversion brackets to mount to the frame, 4) Mustang spherical housing bearings, 5) adjustable G-body lower control arms, and 6) new brake lines. If you plan on driving your G-body on the street, an aftermarket emergency brake cable kit would also be a good idea. Last, but not least, you will need to rectify the incompatibility of the bolt pattern. This is where things can get complicated. Depending on your goals and application, the preferred methods will vary. These are our suggestions:
© Provided by Hotrod Rear
The Fox-body Mustang rear is the closest in width to the G-body, and is highly recommended. It comes with a posi differential, 28-spline axles with a 4x4.25-inch bolt pattern, drum brakes, and any one of a several underwhelming gear ratios. You'll need to remove the "quad shocks" and remove the brackets that mount them. A Mustang sway bar isn't needed because you can use standard U-bolts and brackets with a G-body sway bar. However, you will need to weld on G-body spring perches. Call DTS if the stockers are too rusted to remove.
© Provided by Hotrod Drums
The Fox-body rear comes with 4-lug drum brakes, but there are kits to convert to 5-lug axles and drums for around $400. You can purchase custom C-clip 28-spline axles from Moser if you want a GM bolt pattern and brakes, but this could prove problematic. New brake (hard) lines and a Lokar emergency-brake cable kit are also needed to complete the swap.
© Provided by Hotrod Driveshaft
Instead of the GM-style U-joint, the 8.8-inch rear comes with a flat-flange-style pinion yoke. This will need to be rectified with a new driveshaft, which you should replace anyways if you plan on making enough power to break a stock 10-bolt. Some have gotten away with simply changing to a Moser 1350 pinion flange. Note that the upper control arm bushings are retained in the housing, which is another significant difference from the GM rear.
Street/Strip On the Cheap
The easiest and simplest way to pull off this swap is to use the complete Fox-body rearend, including the axles and drum brakes. Purchase a set of 15-inch drag wheels with a Ford (4-lug) bolt-pattern and a half-inch less backspacing to account for the difference in width. Weld Racing's S71 wheels start at $285, but you might be able to pick up a used set of Draglites for cheap. We have seen some people drill the Mustang axles for the GM bolt pattern (and use the factory G-body brakes), but this is not recommended since it weakens the axle and will most likely break at the most inopportune moment.
© Provided by Hotrod Weldracing4lugs71wheels
Hardcore Drag Racer
If you plan on sidestepping the clutch or dumping the trans brake with a set of slicks, then you'll need something stronger than the factory 28-spline axles. We'd recommend stepping up to Strange Engineering's 35-spline axle package, which includes a lightweight chrome-moly spool and C-clip eliminators. This is the safest and most reliable option for going fast at the drag strip—no more one-wheel-peels or ejecting axles. Remember, the NHRA requires C-clip eliminators to go 10.99 or faster. Best of all, we've seen these packages on sale for less than $450. You can take the opportunity to switch to a GM bolt pattern (5x4.75), stick with factory GM drum brakes, and possibly even trim a little of the width off the axle tube. This makes wheel selection quite a bit easier, and gives you a near bulletproof setup. The only down side is that it is the least street-friendly of all options. Thankfully, Strange's tapered-style bearing (cone-type roller) handles side loads better than a traditional C-clip eliminator, but the spool can be a deal-breaker for most.
© Provided by Hotrod Spool Packages Edited 1
Autocross Cruiser
If your G-body sees mostly street duty and the occasional autocross, we'd recommend starting with the Fox-body rear and purchasing a 5-lug rear disc conversion kit. Late Model Restoration makes a complete kit with everything you need (down to the gear oil and brake fluid) for just under $1,650. That may seem steep, but it really is all-inclusive. The SVE rear brakes are 1994-–2004 Cobra spec, so they are fairly stout. The rotors and pads come from StopTech, and the brake lines are braided stainless steel. It also comes with an SSBC proportioning valve, which is key to getting the bias right. Otherwise, you could be locking up the rear brakes every time you touch the pedal. And you can sell the 1993 Cobra master cylinder that is included in the kit to invest in a C5 front brake conversion. The only catch is that you will need wheels for the Mustang bolt pattern in the rear and GM in the front. These Rocket Booster Hyper Shot wheels from Rocket Racing are around $250 to $300 per wheel, which is quite a bit cheaper than any custom wheel and will look right at home on a G-body.
© Provided by Hotrod Rocket Wheels
© Provided by Hotrod Latemodelresto5 Lug
Pro Touring
If you anticipate putting extreme lateral loads on your G-body, the best option is to cut the axle housing, weld on Strange's Late Big Ford 9-inch ends (PN H1137), and install custom axles. This requires more skill than the other two options, but it gives you the most optimum bearings, regular GM bolt pattern wheels, and negates the C-clips. If you plan on using a set of large rear brakes with a fixed caliper, this is the only option, – otherwise you run the risk of pad knock-back. Wilwood has a bolt-on set of set of four-piston brakes (PN 140-9219) that will provide all the clamping force you need, while stuffing under 18-inch wheels. And since you saved a grand on the housing, you can afford 31-spline axles and a Detroit Truetrac diff to eliminate any weak links. All in with the brakes, axles, diff, and housing ends, you can expect to pay around $2,200. Note: For an appropriate ride height (for Pro Touring), coilovers or shorter shocks are recommended since the shock mounts may be slightly higher on the 8.8-inch housing. Traditional lowering springs may fall out at full extension of standard G-body shocks.
© Provided by Hotrod Spherical Bearings
The 8.8's rubber housing bushings will need to be replaced by spherical bearings to provide enough articulation to accommodate the altered geometry. These are from TRZ Motorsports and cost $105 for the pair.
© Provided by Hotrod Upper Control Armbrackets
There are a couple 8.8 G-body conversion kits out there; this one is from Baseline Suspensions and costs $320. It includes a Zinc-plate bracket that bolts to the frame to alter the upper control arm mounting position, and an adjustable Mustang style upper control arm. Extended-length, adjustable lower control arms are also available. You will need to drill a hole in the torque box to mount the upper control arm bracket, and a small bead of weld wouldn't hurt either. You can also consider a kit from Trick Chassis or making your own with Fox-body brackets and upper control arms from TRZ.
© Provided by Hotrod Final
Here is a build in progress using the Baseline Suspensions kit with Detroit Speed lower control arms, springs, shocks, and sway bar. The adjustable lower control arms are key to providing the added length needed, along with some spacers to make them snug in the bracket. In retrospect, the owner believes coilovers would have been a better alternative to purchasing new spring perches and welding them on since the shocks appear to be too long. The attraction of attempting this swap, you might say, is the fun of solving problems like this.
© Provided by Hotrod Lead
Hot Rod Scott Parker, Manufacturer, Dave Rushen2 days ago
For years, the supply of G-body 8.5-inch rearends seemed it would never dry up, making them a cost- effective and easy replacement for the maligned 7.5- or 7.625-inch 10-bolt. Now those days are behind us, so your choices are: continue breaking 10-bolt ring gears or pony up some serious coin for an aftermarket housing. There is a road less traveled, though, that involves salvaging a Ford 8.8-inch rear from a junkyard.
Before we walk you through the process of swapping an 8.8-inch rear into a G-body, let's start with a little background. The Olds 442, Buick Grand National, and later T-types (as well as Turbo T Limited) were the only G-bodies that came from the factory with an 8.5-inch 10-bolt rearend (RPO GU6 and GT4). Even the mighty Chevy Monte Carlo SS was relegated to the smaller ring gear. Though some impressive feats have been pulled off with the diminutive 7.5, more often than not, it is a source of a failure with sticky tires or numerically higher ratio gears—even on the road course.
Since no other rear matches the G-body's suspension and mounting points, an aftermarket housing (12-bolt, 9-inch, or S60) is the only bolt-in rearend. But with a little elbow grease, you can make the Ford 8.8-inch rear a viable solution for the G-body at a fraction of the cost. Step one is to locate a solid rearend. Thankfully, 8.8s are plentiful in the boneyard, and often you can pick one up cheaply from a Mustang buddy who is swapping to a 9-inch. Keep in mind, though, that width, gear ratio, differential type, brakes, and bolt pattern will vary per application. Here is an incomplete list of 8.8-inch rears to choose from:
Model YearModelAxle WidthBrakesBolt Pattern1986–1993Mustang V-858.75Drum4x4.251990–1997Ranger58.750Drum5x4.501994–2003Explorer59.750Drum or disc5x4.501990–1995Aerostar59.750Drum5x4.501979-2002Crown Victoria62.80Drum or disc5x4.501987–1988Thunderbird Turbo Coupe61.50Disc4x4.251984–1992Lincoln Mark VII61.50Disc5x4.501994–1998Mustang60.250Disc5x4.501999–2004Mustang61.6250Disc5x4.50
Unless you plan to cut and narrow the rear, the Fox-body rear is by far the best choice of the bunch, since it is the closest to the factory G-body width (57.25-inches). Though the Ranger rearend is the same width and comes with 5-lug axles, as well as 3.73:1 or 4.11:1 gears, you will want to steer clear. The differential is offset in the Ranger, making driveshaft alignment impossible with a 200-4R, TH350, T56, or other GM trans of your choosing. In addition, most have an open differential, which is no good for a performance application. The Mustang's Traction-Lok is a clutch-based limited-slip differential that is rebuildable and sturdy. However, hardcore drag racers may want a spool, while road racers can use the FRPP carbon rebuild kit or go with a gear-based limited slip (such as a Truetrac). Unlike the smaller 10-bolts, there are plenty of aftermarket options for the 8.8-inch from the differential to gear ratios, axles, and C-clip eliminators. And let's face it; if you break the ring gear in a properly built 8.8, you deserve a medal.
Before you lay down some dough on an 8.8, it's important to make a game plan. At the very least, retrofitting the rearend in a G-body will require: 1) a new driveshaft to match the flat-flange-style pinion yoke, 2) cutting off the old spring perches and welding on a G-body set, 3) Mustang adjustable upper control arms with conversion brackets to mount to the frame, 4) Mustang spherical housing bearings, 5) adjustable G-body lower control arms, and 6) new brake lines. If you plan on driving your G-body on the street, an aftermarket emergency brake cable kit would also be a good idea. Last, but not least, you will need to rectify the incompatibility of the bolt pattern. This is where things can get complicated. Depending on your goals and application, the preferred methods will vary. These are our suggestions:
© Provided by Hotrod Rear The Fox-body Mustang rear is the closest in width to the G-body, and is highly recommended. It comes with a posi differential, 28-spline axles with a 4x4.25-inch bolt pattern, drum brakes, and any one of a several underwhelming gear ratios. You'll need to remove the "quad shocks" and remove the brackets that mount them. A Mustang sway bar isn't needed because you can use standard U-bolts and brackets with a G-body sway bar. However, you will need to weld on G-body spring perches. Call DTS if the stockers are too rusted to remove.
© Provided by Hotrod Drums The Fox-body rear comes with 4-lug drum brakes, but there are kits to convert to 5-lug axles and drums for around $400. You can purchase custom C-clip 28-spline axles from Moser if you want a GM bolt pattern and brakes, but this could prove problematic. New brake (hard) lines and a Lokar emergency-brake cable kit are also needed to complete the swap.
© Provided by Hotrod Driveshaft Instead of the GM-style U-joint, the 8.8-inch rear comes with a flat-flange-style pinion yoke. This will need to be rectified with a new driveshaft, which you should replace anyways if you plan on making enough power to break a stock 10-bolt. Some have gotten away with simply changing to a Moser 1350 pinion flange. Note that the upper control arm bushings are retained in the housing, which is another significant difference from the GM rear.
Street/Strip On the Cheap
The easiest and simplest way to pull off this swap is to use the complete Fox-body rearend, including the axles and drum brakes. Purchase a set of 15-inch drag wheels with a Ford (4-lug) bolt-pattern and a half-inch less backspacing to account for the difference in width. Weld Racing's S71 wheels start at $285, but you might be able to pick up a used set of Draglites for cheap. We have seen some people drill the Mustang axles for the GM bolt pattern (and use the factory G-body brakes), but this is not recommended since it weakens the axle and will most likely break at the most inopportune moment.
© Provided by Hotrod Weldracing4lugs71wheels Hardcore Drag Racer
If you plan on sidestepping the clutch or dumping the trans brake with a set of slicks, then you'll need something stronger than the factory 28-spline axles. We'd recommend stepping up to Strange Engineering's 35-spline axle package, which includes a lightweight chrome-moly spool and C-clip eliminators. This is the safest and most reliable option for going fast at the drag strip—no more one-wheel-peels or ejecting axles. Remember, the NHRA requires C-clip eliminators to go 10.99 or faster. Best of all, we've seen these packages on sale for less than $450. You can take the opportunity to switch to a GM bolt pattern (5x4.75), stick with factory GM drum brakes, and possibly even trim a little of the width off the axle tube. This makes wheel selection quite a bit easier, and gives you a near bulletproof setup. The only down side is that it is the least street-friendly of all options. Thankfully, Strange's tapered-style bearing (cone-type roller) handles side loads better than a traditional C-clip eliminator, but the spool can be a deal-breaker for most.
© Provided by Hotrod Spool Packages Edited 1 Autocross Cruiser
If your G-body sees mostly street duty and the occasional autocross, we'd recommend starting with the Fox-body rear and purchasing a 5-lug rear disc conversion kit. Late Model Restoration makes a complete kit with everything you need (down to the gear oil and brake fluid) for just under $1,650. That may seem steep, but it really is all-inclusive. The SVE rear brakes are 1994-–2004 Cobra spec, so they are fairly stout. The rotors and pads come from StopTech, and the brake lines are braided stainless steel. It also comes with an SSBC proportioning valve, which is key to getting the bias right. Otherwise, you could be locking up the rear brakes every time you touch the pedal. And you can sell the 1993 Cobra master cylinder that is included in the kit to invest in a C5 front brake conversion. The only catch is that you will need wheels for the Mustang bolt pattern in the rear and GM in the front. These Rocket Booster Hyper Shot wheels from Rocket Racing are around $250 to $300 per wheel, which is quite a bit cheaper than any custom wheel and will look right at home on a G-body.
© Provided by Hotrod Rocket Wheels © Provided by Hotrod Latemodelresto5 Lug Pro Touring
If you anticipate putting extreme lateral loads on your G-body, the best option is to cut the axle housing, weld on Strange's Late Big Ford 9-inch ends (PN H1137), and install custom axles. This requires more skill than the other two options, but it gives you the most optimum bearings, regular GM bolt pattern wheels, and negates the C-clips. If you plan on using a set of large rear brakes with a fixed caliper, this is the only option, – otherwise you run the risk of pad knock-back. Wilwood has a bolt-on set of set of four-piston brakes (PN 140-9219) that will provide all the clamping force you need, while stuffing under 18-inch wheels. And since you saved a grand on the housing, you can afford 31-spline axles and a Detroit Truetrac diff to eliminate any weak links. All in with the brakes, axles, diff, and housing ends, you can expect to pay around $2,200. Note: For an appropriate ride height (for Pro Touring), coilovers or shorter shocks are recommended since the shock mounts may be slightly higher on the 8.8-inch housing. Traditional lowering springs may fall out at full extension of standard G-body shocks.
© Provided by Hotrod Spherical Bearings The 8.8's rubber housing bushings will need to be replaced by spherical bearings to provide enough articulation to accommodate the altered geometry. These are from TRZ Motorsports and cost $105 for the pair.
© Provided by Hotrod Upper Control Armbrackets There are a couple 8.8 G-body conversion kits out there; this one is from Baseline Suspensions and costs $320. It includes a Zinc-plate bracket that bolts to the frame to alter the upper control arm mounting position, and an adjustable Mustang style upper control arm. Extended-length, adjustable lower control arms are also available. You will need to drill a hole in the torque box to mount the upper control arm bracket, and a small bead of weld wouldn't hurt either. You can also consider a kit from Trick Chassis or making your own with Fox-body brackets and upper control arms from TRZ.
© Provided by Hotrod Final Here is a build in progress using the Baseline Suspensions kit with Detroit Speed lower control arms, springs, shocks, and sway bar. The adjustable lower control arms are key to providing the added length needed, along with some spacers to make them snug in the bracket. In retrospect, the owner believes coilovers would have been a better alternative to purchasing new spring perches and welding them on since the shocks appear to be too long. The attraction of attempting this swap, you might say, is the fun of solving problems like this.
© Provided by Hotrod Lead
#3
12-06-2014, 11:58 AM
The GM G-Body
the GM G-body cars produced from 1982-1988. Most car model designs remained unchanged from the 1981 model year. GM split off the G-body from the A-body line in 1982. The 1988 models (Cutlass, Monte Carlo) were cars remaining from the 1987 production year and just sold as 1988 models, with the Cutlass using the "Classic" name postfix.
Which cars are G-bodies?
The G-body cars include the Buick Regal/Grand National/GNX, Chevrolet Monte Carlo, Chevrolet El Camino, Chevrolet Malibu, GMC Caballero, Oldsmobile Cutlass (Supreme/Calais/Cruiser/Salon), Pontiac Grand Prix, the Pontiac Grand LeMans, and the Pontiac Bonneville.
The G-body cars were some of the most popular cars of the 1980s. Oldsmobile had record sales because of the Cutlass. The Chevy Monte Carlo SS was popularized by NASCAR. And the Buick GNX/GN/Turbo Regals were sought after by those searching for some of the fastest U.S. production cars at the time.
The G-body remains popular to this day. They are a great platform to build a high performance car and to restore. With the number of cars available, along with the numerous aftermarket vendors supplying everything from performance parts to body parts, it's no wonder why G-bodies are popular with many people.
Above from ^ Super Site (Thank You)
Featured G-body
86CutlassUCF's 1986 Oldsmobile Cutlass Salon
the GM G-body cars produced from 1982-1988. Most car model designs remained unchanged from the 1981 model year. GM split off the G-body from the A-body line in 1982. The 1988 models (Cutlass, Monte Carlo) were cars remaining from the 1987 production year and just sold as 1988 models, with the Cutlass using the "Classic" name postfix.
Which cars are G-bodies?
The G-body cars include the Buick Regal/Grand National/GNX, Chevrolet Monte Carlo, Chevrolet El Camino, Chevrolet Malibu, GMC Caballero, Oldsmobile Cutlass (Supreme/Calais/Cruiser/Salon), Pontiac Grand Prix, the Pontiac Grand LeMans, and the Pontiac Bonneville.
The G-body cars were some of the most popular cars of the 1980s. Oldsmobile had record sales because of the Cutlass. The Chevy Monte Carlo SS was popularized by NASCAR. And the Buick GNX/GN/Turbo Regals were sought after by those searching for some of the fastest U.S. production cars at the time.
The G-body remains popular to this day. They are a great platform to build a high performance car and to restore. With the number of cars available, along with the numerous aftermarket vendors supplying everything from performance parts to body parts, it's no wonder why G-bodies are popular with many people.
Above from ^ Super Site (Thank You)
>Just because she's Beautiful 2 `me<
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