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RX-7 1st Gen Specific (1979-85) RX-7 1979-85 Discussion including performance modifications and technical support sections |
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02-13-2012, 12:37 AM | #1 |
RCC Contributor
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researching the 8.8 swap
I've just started researching the 8.8 swap and to say the least ive got several questions. I've found several different threads with people asking similar questions and most answer just do the grannies swap. Thats great and there stuff looks very well put together but that is a good bit a money when a lot of it can be custom.
So I figure why not start one big thread with as much info about this swap and hopefully pictures of other people builds in one spot might also make it easier to understand. onto what I've learned so far -you want a 8.8/9, the 8.8 is the what most people use - the 8.8 comes in a lot of vehicles early 90 model mustang, explorers and several others (look at links) - most likely will have to be shortened unless you go widebody/flared -the mustang rear end has a centered diff the explorer diff is off center Links -Grannys kit* http://grannysspeedshop.com/ -8.8 Facts and Measurements * http://www.explorerforum.com/forums/...d.php?t=235261 INFO - this info is from all over http://www.allfordmustangs.com/forum...6-mustang.html The 8.8 is found in Rangers and Explorers most commonly but the Explorer rear end is more sought after as it is a 31 spline vs 28. Also, 95 and up Explorers have disc brakes that can easily be utilized. Explorer Sport editions (two door) as well as the later Sport Tracs always came with a stock Posi-Trac. These are identified by an "L" after the first number of the ratio on the tag that gets bolted to the diff cover. From example if you had 4.10 gears and a locker, it would read: 4L10. If it was a stock 3.5 without a locker it would be 350. The explorers came stock with 3.5's, 3.73's (optional locker) and 4.10's with a mandatory locker option. Your best bet is a 95 and up Explorer Sport rear end as they have have the 31 spline axle, locker and are perfect to modify for an early mustang. The early Mustangs measured 57.25" flange to flange. The Explorer rear end is 2.5" wider (59.75"), however, it has an off set pinion 2.48" to the passenger/right side. What I've heard people can do is cut the drivers side tube by 2.48", weld in a new end and correct for the offset, as well as creating a perfect width axle for an early mustang. Now instead of going out and buying a custom width axle shaft, you can use a second passenger side shaft that is already the right size. This is the part I am not sure about, and that is what I would like to check with someone that has done this swap before. I have heard from a few people that you can reuse the spring perches by just welding a slightly wider plate to adapt it to fit the stock mustang leafs. Another thing to take into account is that the axle tube larger than an 8inch/9inch at 3.25". Also, in case you don't know, the shafts are held in place by C-clips, so if they do brake, your entire wheel/hub/shaft/brakes can side right out of the tube on you. My brother this this 4x4ing in his ranger and it caused all kinds of problems. If you really plan on beating on the rear end, C-clip eliminators are a good option. These axles are very strong stock. That is why you see tons of guys starting to catch on and use them. The Chevy guys are onto them as well and I've seen several in Chevs at shows. They will handle upwards of 500hp without any problems (no more power than 90% of guys will have). xxxx http://www.allfordmustangs.com/forum...ang-swaps.html If you find both your lucky. Best thing to do is just go to the junkyard and get the rear end and then get the gt40 heads from an explorer that has them. At my junkyard i couldn't find any v8 explorers, but then again i wasn't looking but most were v6s. When picking a rear end look at the tag on the cover and the numbers you want to look for are 3L55 3L73 and 4L10 which are 3.55 3.73 and 4.10 rear ends equipped with not a locker (none had a locker) but fords traction lock which is essentially a posi. altho i can tell you that my 2 rear wheels lock up every time i hit the floor, lol. xxxx http://www.allfordmustangs.com/forum...ml#post1749485 Yep, '95' and up have the disc brakes. xxx GEAR RATIO-i find it very important You can look on the label plate on the drivers door for the codes, here is what they indicate) http://www.jeepforum.com/forum/f11/e...-swap-1001827/ 41 Open 8.8" 3200 3.27 43 Open 8.8" 3200 3.08 44 Open 8.8" 3200 3.73 45 Open 8.8" 3200 3.55 D1 L/S 8.8" 3200 3.27 D2 L/S 8.8" 3200 4.10 D4 L/S 8.8" 3200 3.73 D5 L/S 8.8" 3200 3.73 L - Limited Slip Differential C - Conventional Differential ..... 1.) Spring Perch location and angle (been discussed) 2.) Overall width, my 8.8 from a 2003 explorer is about a 1/2" wider than stock. Not too big of a deal unless you already maxed out your tire/wheel sizes. 3.) The disk brake set-up may require a different master cylinder to accomodate the different volume of brake fluid required to fully actuate the rear brakes. And/Or a proportioning valve to adjust/balance your front to back brakes. 4.) If you have your car lowered, the offset pumpkin will likely cause the diff yoke/driveshaft to hit the passenger side tunnel under the back seat at least at the bumps in the road. This can be fixed with a hammer if you don't mind. 5.) The rear drive shaft yoke may have to be changed, but I'm not sure about this - my drive shaft is still in the shed and I plan on going to an AOD so I'll have to check both of my yokes. 6.) Your rear wheels will need to clear the new disc set-up. 14s won't unless your backspacing is near nil which is highly unlikely. 7) The shock plates and U-bolts will have to be changed to accommodate the difference in axel tube diameter. My 8.8 was 3.25 inches where the stock 4 lugger was 3. Currie carries these. xxx http://www.allfordmustangs.com/forum...ang-swaps.html
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85 rx7 gsl-se - AA tags/ never ending project will never run |
02-13-2012, 12:43 AM | #2 |
RCC Contributor
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Next is the suspension arms, grannys kit lets you keep the stock arms or you can use there torque brace.
theres also the gforce kit for 3 link and pan hard for stock rear end http://www.gforceengineering.net/products.htm I've seen builds using 4 links, 3 links, panhard bars, the straight bar (top of the diff to inside the car) this is where Ive got most of my questions as most of the builds I've seen they don't go into great detail about this. So more details and pics for this would be greatly appreciated.
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85 rx7 gsl-se - AA tags/ never ending project will never run |
02-13-2012, 03:31 AM | #3 |
Respecognize!
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turbocoupe 8.8 (no offset) then two ranger 8.8 short side axles to get 5x4.5
With that, way are you wanting an 8.8?
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02-13-2012, 08:36 AM | #4 |
RCC Contributor
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Couple reasons im going fc subframe in the front, mine needs to be rebuilt, and im going to try to go turbo next year so this way it'll be beefed up rear end and ill have tons of diff choices
So far from what I've read se rear ends are only good for like 350 I want a little more then that and im wanting to go to a better gear then a 411. I know there heavier but id rather have a little overkill
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85 rx7 gsl-se - AA tags/ never ending project will never run |
02-13-2012, 09:10 PM | #5 |
The Newbie
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In the middle of installing a 96 explorer rear end in a 1st gen. Narrowed the driverside axle tube to the same length as the passenger side. Puts the pinion in the center of the trans tunnel.
http://am.wrex-racing.com/index.php?topic=1314.30 First time doing this and not one who cares about how it looks, as long as the job get done. chuck |
02-14-2012, 12:40 AM | #6 |
Rotary Fanatic
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the 8.8 rear ends are almost the same as a 10 bolt chevy , just wondering why the ford 8 " with 28 splines are not the popular choice :1.same axels as the early 9" 2.easy to get parts 3. no "c"clips 4.you can set up the 3rd member out of the housing ,so 3rd member swaps for gears is quick and easy(about an hour).
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02-14-2012, 10:25 AM | #7 |
The Newbie
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Reason for me going with a 8.8 out of a explorer was (200$) cost, pick n pull is full of them and easy install. The explorer comes with 31 spine axles and a gear ratio I can live with. 3.73 LSD. The extra short axle cost a extra 20$. IMHO at 2400/2500 lbs the c-clip eliminators are not a must have option. I will never break a 31 spline axle. The stock turboII trans will break first.
If kept at factory length a 8 inch wide wheel would work well with a 6+ inch offset. The pinion offsets to the passenger side but is doable. Narrowing the drivers side put the pinion in the middle of the tunnel. And Since the rear end is shorter my options for wheels and offset are greater. 8 inch wide with 5.5 offset and a one inch spacer puts the wheel/tire perfectly in the wheel well. Going to try and fit a 9 inch wheel with 5.5 offset under the car after everything is done. Just not sure if I want to roll the fenders. |
02-21-2012, 10:31 PM | #8 |
RCC Contributor
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Gravity I sent you a pm
Everything I've seen c clips aren't a issue unless you've got serious power like sleeper said. Also sleeper what are you doing for suspension?
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85 rx7 gsl-se - AA tags/ never ending project will never run |
02-23-2012, 11:25 AM | #10 |
Rotary parts manufacture
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Nice work guys..
I understand the need for a tougher rear end especially for the first gens tiny axles and limited gear selections. For this reason we are putting together a Toyota 8" rear package for the first gen or other interesting swaps starting @ 53" to 58" WMS-WMS Will have a dedicated post up in our vendor section. Goopy Performance |
02-23-2012, 05:07 PM | #11 |
RCC Contributor
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What are y'all doing as far exhaust all the suspension. Setups seem like they have issues when it comes to routing the exhaust (4 link, after market watts link) all seem to get in the way.
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85 rx7 gsl-se - AA tags/ never ending project will never run |
02-23-2012, 06:03 PM | #12 |
The Newbie
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Under the axle. 3" exhaust under axle, 4" turbo back.
Got the car to the track last night. Very lite passes and things seem good and strait. Easy to drive with the 3.73 gear and 26" tires. For the price and ease, you can't go wrong with the explorer rear end. Last edited by sleeper7; 02-23-2012 at 06:20 PM.. |