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Ford 8.8 conversion |
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farna
Supporter of TheAMCForum Moderator Lost Dealership Project Joined: Jul/08/2007 Location: South Carolina Status: Offline Points: 19692 |
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A 93-09 Ranger axle is 58.5" wheel mounting surface to WMS. That fits some of the big cars (coil springs though) and the 71-74 Javelin nicely. You will have to change the driveshaft (have one made) and change the spring perch locations. That's about 1.5" narrower than the stock Javelin axle, but a pair of 3/4" spacers would fix that. The Explorer axle is 60" wide and perfect for the 71-74 Javelin. The diff is offset to one side a bit, but that's not an issue. For the 68-70 models use the Explorer axle and shorten the long side tube to fit a short side axle. That narrows it to about the same length as the original axle. |
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Frank Swygert
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Mopar_guy
Supporter of TheAMCForum Joined: Jun/07/2009 Location: Ohio Status: Offline Points: 4837 |
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I'll beg to differ on the bold part of your statement Frank from the experience I had last year doing the exact swap you're talking about. I posted it in Frankenrambler and I'll repost it here again so someone else doesn't make the same mistake I did in my 73. I know from experience earlier this year that
having an offset pinion angle can add vibration if not properly done. I
put an 8.8 Explorer rear in my Javelin and since I needed the full
width, I ended up with the pinion 2" offset. With the standard 2.5° down
angle on the engine/trans and the pinion going up 2.5°, I had over a 3°
U joint angle and it vibrated so bad it wasn't drive able above 60 mph. I
managed to raise the trans a little so I was at 2.1° and matched the
pinion to it and it only lowered the operating angle to 2.9°. It still
vibrates but it's not bad until I get to 75 -80 mph is where it's the
worse. That rear is coming out and getting a 9" with a centered pinion
because I can't straighten out the engine/trans angle enough to lower
the operating angle. Since you're building it now, you can avoid a
situation like this by reading that book and watching your angles and
offset. The best tool I found to measure the angle is called "Bubble
level" a free app I got for my phone. It reads angle with one decimal
point which is enough. This whole deal was a big, time consuming,
learning experience for me as I thought I knew what I was doing having
messed with U joint angles when I worked at dealerships. I highly suggest doing some reading in this book from Spicer before you start welding to much. http://media.spicerparts.com/cfs/files/media/4ohobHpp8jBQnRpq4/j3311-1-dssp.pdf?token=eyJhdXRoVG9rZW4iOiIifQ%3D%3D&store=original They also have U joint angle calculator and a Torsional Analysis calculator on their website that will show you what the operating angles will be. The latter is really good when working with compound angles but be sure to read how they relate to the angles when entering your numbers in. http://spicerparts.com/calculators/torsional-analysis-calculator Basically the offset adds to your total joint angle. For example, if you
use the torsional calculator with the following numbers which is close
to what I have, on the first page I entered 3700 rpm for shaft speed. Second page, 0 angle and 38" long. Third page, 2° down for driving and 2° up for driven - that's the parallel angels to cancel U joint vibration. Fourth page, this is where you enter the offset. I have 2". Now go to the results page and now it's showing 3.62° for each joint and 4.91° torsional. You'll note what the maximum angles are shown in the red down at the bottom. If you go back to the offset page and change the number to 0" and then go back to the results page, you'll now see the U joint angles are 2° and the torsional is 0 because the parallel angels on the U joins are the same. I also have read somewhere, maybe in that manual, that above 3° U joint angle, it will cause vibration which I have come to find out is true. One other thing to note is the shaft speed does play heavy on this. With the 3.73 gear and 26" tall tires on my car, 3700 on my car is about 80 mph but if you have a lower gear ratio, your torsional numbers are going to be lower. Try going back to the first page and lower the shaft speed to 2600 rpm and see what you get. By changing the numbers around and see the effect they have, you can get a good idea of how it all works together and what you need to change before welding it all up. Its a great tool to avoid driveline vibration while you build your car. Here's a link to all their calculators. http://spicerparts.com/calculators If it helps just one person with their build/problem, it's worth posting then. The post is here with tomj and I discussing it. http://theamcforum.com/forum/1964-rambler-classic-street-strip-conversion_topic90597_post804254.html?KW=#804254 |
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"Hemilina" My 1973, 5.7 Hemi swapped Javelin |
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farna
Supporter of TheAMCForum Moderator Lost Dealership Project Joined: Jul/08/2007 Location: South Carolina Status: Offline Points: 19692 |
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Yes, it does need to be set up right... I over simplified.
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Frank Swygert
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Red Devil
AMC Addicted Joined: Jul/10/2007 Location: Canada Status: Offline Points: 1743 |
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Also of note, the 71-74 Javelin has a Tread Width = 60". The WMS to WMS width = 61" (+/- depending on drum thickness). The wheel disc is offset from the rim centreline, so the tread width is narrower than axle mounting surface width. The pinion is also not centred. I measured my '74 and it was offset 9/16" to the passenger's side. Maybe a later Mustang rear would be a closer fit for the Javelin? My conclusions from this thread: (1) If you have an AMC 20 in good condition and your car is a cruiser, keep it. There is a pretty good selection of ring & pinion ratios, carriers, disc brake kits (if you really have to have discs), differential covers, etc. ... and it keeps one more factory part in your AMC (... if you like to keep your car mostly factory). (2) If it's a mild street-strip build with sticky tires, get one piece axle shafts, reinforce the perches and see (1). Dr.Diff's for an economical option, if you have the ability to cut them to suit. Moser, Dutchman, etc. if not. Weld on Ford 9" ends or retube completely for more serious use, and to get better bearing and brake kit options ... but if not an AMC purest, option (5) may be a better plan. (3) If you are a scrounger and trust your local fab shop to rework it, or your own skills, go to the boneyard and find a good Ford 8.8" or two and go from there ... but it may also need some upgrades, depending on application ... but a bit lower cost than similar upgrades to the AMC 20. Some mating parts need to change. (4) If you "know a guy" who has an early Ford 9" or Mopar 8 3/4" for sale that's the right fit, it may be the closest to a "bolt-in-no-weld" option ... without spending a bunch of cash to choose option (5). Expect some bolt-on parts may also need changing, e.g. driveshaft, u-bolts, shock mounts, etc. (5) If your AMC 20 is junk, you've had no luck finding one in the "Wanted" section, your build will push the old AMC 20 beyond its limits, or you simply want something with unlimited options, custom order a 9" to your specifications (as mentioned earlier in the thread) ... or if fewer options are ok and you hate Fords, a Dana 60 ... or a Mopar 8 3/4 ... or a custom 12 bolt if you like Chevies ... or a custom 8.8 if you really want an 8.8. Depending on options, typically range from $2500 up. Lots of places building various custom rear axle combinations ... Ford 9" is still most popular with best selection of gear ratios, carriers, etc. ... but can get expensive quick depending which options you select. Hope this helps, RD.
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iwantmyx
AMC Apprentice Joined: Jun/14/2018 Location: texas Status: Offline Points: 45 |
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Thanks for everyone's help. The 74 I bought has a 6 cyl rear end in it. It also has a 360 with mild cam and a 727 with a shift kit. I just put 295 50 15's on the back and am afraid I will blow the rear end. I really don't have the resources to do anything myself and have limited funds. At least I now know my options and will really have to put some thought into what to do. Thanks again!
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farna
Supporter of TheAMCForum Moderator Lost Dealership Project Joined: Jul/08/2007 Location: South Carolina Status: Offline Points: 19692 |
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With the wide tires I wouldn't be doing many burn-outs. I don't think you'll blow the rear end, it's tougher than you think and you have no weight in the rear. What you're more likely to do is spin a hub, usually the right side. So go out there and loosen the hub nuts, then tighten back down (with tire jacked off floor... preferably tire not on) to 250-300 ft/lbs. No point in going over 300, that just adds stress. Factory says 250, and that's enough. If the nuts have never been off it will take more than 300 ft/lbs to loosen, but stuck isn't the same as properly torqued. Barring spinning a hub you will increase the wear on the internals. With normal driving, even with the wide tires, you won't hurt anything. But with those tires and the power you have, I bet you REALLY want to show off a bit...
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Frank Swygert
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iwantmyx
AMC Apprentice Joined: Jun/14/2018 Location: texas Status: Offline Points: 45 |
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Although I am in my 60s I still love the smell of tire smoke in the morning. Actually any time if the day. I will definitely check the torque on the hubs. Thanks again for your help!
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Dan1500
AMC Apprentice Joined: May/26/2019 Location: Auburn, IN Status: Offline Points: 70 |
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Sorry to bring up an old thread but my question is related. For those who have went to the 8.8 with disc brakes are there any issues with caliper clearance when using 14" rims?
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Trader
AMC Addicted Joined: May/15/2018 Location: Ontario Status: Offline Points: 6913 |
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The Explorer 8.8 have different calipers listed on Rock Auto then the Ranger 8.8.
I have only worked with the Explorer. I always center the pumpkin and with it's calipers you need 15" rims. With the drum brakes the 14" rim is fine (these bolt on so you can switch back an forth). I use bolt on adapters to get the width on large cars. No knowledge of the Ranger. |
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Dan1500
AMC Apprentice Joined: May/26/2019 Location: Auburn, IN Status: Offline Points: 70 |
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Thanks Trader, I kind of figured that would be the case with the 14" rims. I would like to keep my original aluminum rims so I guess I'll have to investigate the ranger brakes.
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