I've done a few superficial searches and could not find any recent Ford 9" rearend installations. I know its been done before. I know I'm not the first. All my builds have the 9" rearend in them. They are indestructable! Also, I'm all tooled up to overhaul, narrow, set up and install them. It's what I know. I've never laid eys on an 8.8. I've never seen a hot rodder install an 8.8 as an upgrade. I assume they are a great rear end as Ford stuck em in everything. However I'll continue to use the 9". Thought I'd share the installation in a MK4. This installation was cheaper than the Mosier 8.8
The rear axle housing was set up by Quick Performance as a direct replacment installation in 1987 to 1993 Mustang. It has 31 spline axles, Trc-Loc, overhauled differencial, jack pad, drain plug and filler cap in the housing. It comes needing assembly except for the center section. I sourced the Willwood brakes from Summit.
You might consider relatively easy modification to a single center link and add panhard bar. The three link is generally regarded as much better.
I agree the 3 link is better. Factory Five will sell you the 3 link bracket and panhard bar.
The 3 link bracket as it comes from FFR is designed to clamp onto the housing. Forte set up my rearend and he welded the 3 link bracket on which I like better.
Thanks for the tip. I made the decision to use the triagulated four link like the last two builds I did before I ordered the kit. Could have gone the 3 link route from Mosier but did not see any advantage. I'm not an engineer, nor do I road race. I'm a retired helicopter mechanic. Like I mentioned above I've never seen or heard of someone installing an 8.8 3 link in a hot rod as any kind of upgrade over a Ford 9". The triagnulated 4 link with coil overs work great for me, they are in thousands of hot rods, also I'm not a fan of a panhard bar. So not gonna change it, gonna use what I know.
Thanks for the tip. I made the decision to use the triagulated four link like the last two builds I did before I ordered the kit. Could have gone the 3 link route from Mosier but did not see any advantage. I'm not an engineer, nor do I road race. I'm a retired helicopter mechanic. Like I mentioned above I've never seen or heard of someone installing an 8.8 3 link in a hot rod as any kind of upgrade over a Ford 9". The triagnulated 4 link with coil overs work great for me, they are in thousands of hot rods, also I'm not a fan of a panhard bar. So not gonna change it, gonna use what I know.
The 8.8 is actually a pretty good set up and, while not as strong as the 9", can hold a substantial amount of power. Many drag racers have used beefed up 8.8's into the 7 second quarter mile zone. The 9" is stronger due to the hypoid angle of the gears. Unfortunately, this comes at a cost due to reduced efficiency. There are center sections available for the 9" that are based on the Chevy 12 bolt with an improved hypoid angle. Or, if money is no object, Dewco offers a 9" with REM polished gears and ceramic bearings that must be seen to be believed. One of the biggest advantages of the 9" is the available gear ratios... For how 99.99% of the folks are using their FFR's the 8.8 is more than enough for strength.
The issue with the triangulated 4 link is the uppers and lowers are different lengths. As the rear axle articulates the uppers and lowers are moving through different arcs and this causes binding. This is why, for going around corners, it is a bad idea to use heim joints, or even stiff bushings, at the suspension points with a triangulated 4 link. At some point, the bind will cause the wheel rate to go infinite and the rear is going to step out with practically zero chance of recovery. This is what Mustang people refer to as "snap oversteer". That would be a very scary situation in a 2400 lb car with a 90" wheelbase. Mustang suspension experts, such as Maximum Motorsports, suggest using the factory Ford upper control arms if you are limited to using the triangulated 4 link as the soft rubber bushings allow some change in the length during suspension articulation. When using a three link rear, or a torque arm, one must use a heavier rear spring as the wheel rate is reduced because the lack of bind. A fun example is to remove the shocks and springs from the rear. Move the rear axle through its range of motion using a jack. Then remove one of the upper control arms and notice how much more freely the rear axle moves through a greater range.
If you are not going to try to push your roadster "9 10ths" on back roads the four link should work just fine. After all, Ford used this set up on millions of cars.
The 8.8 is actually a pretty good set up and, while not as strong as the 9", can hold a substantial amount of power. Many drag racers have used beefed up 8.8's into the 7 second quarter mile zone. The 9" is stronger due to the hypoid angle of the gears. Unfortunately, this comes at a cost due to reduced efficiency. There are center sections available for the 9" that are based on the Chevy 12 bolt with an improved hypoid angle. Or, if money is no object, Dewco offers a 9" with REM polished gears and ceramic bearings that must be seen to be believed. One of the biggest advantages of the 9" is the available gear ratios... For how 99.99% of the folks are using their FFR's the 8.8 is more than enough for strength.
The issue with the triangulated 4 link is the uppers and lowers are different lengths. As the rear axle articulates the uppers and lowers are moving through different arcs and this causes binding. This is why, for going around corners, it is a bad idea to use heim joints, or even stiff bushings, at the suspension points with a triangulated 4 link. At some point, the bind will cause the wheel rate to go infinite and the rear is going to step out with practically zero chance of recovery. This is what Mustang people refer to as "snap oversteer". That would be a very scary situation in a 2400 lb car with a 90" wheelbase. Mustang suspension experts, such as Maximum Motorsports, suggest using the factory Ford upper control arms if you are limited to using the triangulated 4 link as the soft rubber bushings allow some change in the length during suspension articulation. When using a three link rear, or a torque arm, one must use a heavier rear spring as the wheel rate is reduced because the lack of bind. A fun example is to remove the shocks and springs from the rear. Move the rear axle through its range of motion using a jack. Then remove one of the upper control arms and notice how much more freely the rear axle moves through a greater range.
If you are not going to try to push your roadster "9 10ths" on back roads the four link should work just fine. After all, Ford used this set up on millions of cars.
Great points on the issues with a traiagnulated 4 link. I'm sure I wont be out on the back roads here in Oregon maxing out the rear end. Not just because I'll kill a dozen Lance Armstrong wannabes thinking there on the Tour'de'France, its beacause I have no desire to yard sale it. I will howevver take comfort in the knowledge that I can run 500+ HP into the 9 inch all day long. I dont know that about the 8.8. Also I'm no expert on the origonal Cobras, but Ive not read anywhere that they installed a three link and 8.8.
Just for your perusal.... My Ford 9" Mosier 3 link, Detroit TruTrak, 3.50:1.
One problem that showed up, was the axel boss's were bigger than the Halibrand style (FFR) rims cavity. I had to have the rims machined to fit on the axel boss.
If Brute Force doesn't work, you're not using enough of it. Basic Stuff: MK4 Complete Kit #8439, Wilwood's, 17" Halibrands. Extra Stuff: Stainless brake and fuel lines, Breeze cooling, Battery mount, SS Roll Bar. Old Fart Stuff: Heater, Seat Heaters, Footbox Fresh Air, Stereo, Keyless ignition, Power Steering, Hyd Clutch. Young & Dumb Stuff: 427w Dart, TKO600, 3 link Moser M9/Ford 9", 3.5:1, Eaton TruTrac Posi. Graduation Thread
Maximum Motorsports also recommends to use a panhard bar when running this setup. Lot's of good reading there. I fabed my own and it works well. I think a 9" with a four link is a killer set up once dialed in. Although I do recommend using a panhard bar which also lowers the roll center. 20220430_180905.jpg20220430_180934.jpg20220430_180947.jpg20220430_180856.jpg
Numbers and geometry are constants, but can be misunderstood or misrepresented, and bias can be influential.
Track arms of different lengths swing at different radiuses with different longitudinal displacement.
With high G load the sprung mass can displace laterally from the un-sprung bits.
Track arms at opposing lateral angles that are displaced laterally, become longer and shorter putting push and pull loads on the drive axle. That can induce rear axle steer, which at greater magnitude, must be compensated for.
A Panhard bar also displaces laterally with jounce and/or roll but at 32 to 40 inch length and 4-5 inches travel, the magnitude is ~0.032in, a spark plug gap, and little or no steering effect.
jim
Frank
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i.e.427 Chromed Full Width Roll Bar with integrated LED Third Brake Light.
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OP, show me an original cobra with a 4 link 9" Ford rear. Never seen one
Rich, as I'm sure your well aware the 65 Cobras came with the same Salibury 4HN rear end that would handle everything installed in them from the 260 to the 427. The same rear end AC used. When the Shelby Mustangs came out in 65 they ALL had Ford 9" rear ends. Those rear ends were installed with semi elipticle leaf springs. Far inferior to the 4 link with coil overs. As we are building the Factory Five version of the Cobra we only get the Fox body rear end or the late model IRS to choose from. I could not afford the IRS. I decided to use the superior Ford 9" rear end used in everything Ford made for 30 years. I dont care if a 3 link set up is more stable in hard cornering. I wanted the unparalleled indistructible 9". The only way I could get it was use the 4 link. The 8.8 axle tubes are 2.75" the 9" tubes are 3" so the 3rd link upper bracket that FFR sells will not work on a 9" rear end axle tube.
The reason I posted this thread was to share my experience of installing something unique and different in the hopes others would enjoy the process. Its very doubtfull others will go the same route as I did. Its far eaiser to write a check and install a pre-built plug and play rear end from FFR, or install used parts out of a donor Mustang. This is MY version of a Cobra. I've spent six weeks changing lots of stuff before I hung a single part on it. I've had the FAA telling me how to fix and maintain machines for 45 years, now I get to do things my way!
Let me guess... your an english teacher right?.......If not you should be. Everyone knows mechanics cant spell.....and pilots cant add!!!!
I spent my life with wrenches in my hands not a key board!
Happy trails my freind
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Originally Posted by SteveHsr
