In reply to Pete. (l33t FS) :
Thanks for all the details. Would not have expected the rear on an RX7 to be that wide. I have looked at Speedway full floating rears. Seems way overkill for what I need though.
In reply to Pete. (l33t FS) :
Thanks for all the details. Would not have expected the rear on an RX7 to be that wide. I have looked at Speedway full floating rears. Seems way overkill for what I need though.
We have been running a 7.5 ford in our Lemons Mustang for several years. We have an 8.8 ready to drop in if we ever switch to disc brakes but haven't yet because of it's extra weight.
akylekoz said:We have been running a 7.5 ford in our Lemons Mustang for several years. We have an 8.8 ready to drop in if we ever switch to disc brakes but haven't yet because of it's extra weight.
FYI, there is an easy way to bolt on Mustang discs onto a 7.5 using factory parts.
Patrick said:sidekick/tracker axles are already set up with brackets for a 4 link and track bar.
This is what I came in here to suggest. Grand Vitara/Vitara 99-05 as well. Toyota style pumpkin section.
jmabarone said:akylekoz said:We have been running a 7.5 ford in our Lemons Mustang for several years. We have an 8.8 ready to drop in if we ever switch to disc brakes but haven't yet because of it's extra weight.
FYI, there is an easy way to bolt on Mustang discs onto a 7.5 using factory parts.
Do you have details on this? 4 or 5 lug?
bobzilla said:Patrick said:sidekick/trackers axles are already set up with brackets for a 4 link and track bar.
This is what I came in here to suggest. Grand Vitara/Vitara 99-05 as well. Toyota style pumpkin section.
What gear ratios do they come with? LSDs available?
Racingsnake said:jmabarone said:akylekoz said:We have been running a 7.5 ford in our Lemons Mustang for several years. We have an 8.8 ready to drop in if we ever switch to disc brakes but haven't yet because of it's extra weight.
FYI, there is an easy way to bolt on Mustang discs onto a 7.5 using factory parts.
Do you have details on this? 4 or 5 lug?
5 lug. New parts here, (or junkyards wherever if you're willing to go that route).
Write up on the basic process.
For what it's worth, I have a Ford 7.5 with factory trac-loc, Cobra disc brakes, and an axle girdle that lives behind my supercharged v6/manual trans combo. I'm guessing it's in the 250hp/250 ft-lbs ballpark at the wheels. I don't do drag launches, but it has survived autocross/performance street driving with an aggressive clutch and 295 width tires. The 8.8 is definitely stronger, and parts support for the 7.5 has dwindled in recent years since they stopped using it in Mustangs, but the parts do exist and I haven't broken mine yet.
What is the wms to wms of your Bugeye? I know that Volvo people use the Explorer 8.8" axle and shorten the long side tube to the short side length and use two short side axle shafts to fit under a Volvo. I wonder if the same might work with a Ranger 7.5" which I think is narrower than the 8.8 to begin with? None of this would be a problem if you just put giant box flares on your car. 
I think that the Volvo/Dana 1031 and 1041 are Dana 35 axles with a 7.625" ring gear and 27 spline axle shafts which use the same press-on outer bearings of the Dana 44. So, probably the strongest 7.5" axle you could find.
In reply to VolvoHeretic :
How much V8 power is generally considered the limit for those 1031 axles? Looks like there's decent LSD and rear disc brake options for these.
I really don't know, my Volvo makes little power. At least 300hp behind a turbo 4 banger? Edit: Here is some info on the Volvo rearend. Nothing on strength.
Volvo Limited Slip and Locking Rear End Options
After an hour of looking I found this. No real answers though: what is the max power a (Volvo) solid axle will accept?
In reply to STM317 :
Thanks, that's good info. Any idea how much your 7.5" weighs?
In reply to VolvoHeretic :
Volvo rear is definitely a solid contender. I'd want to change to a more common stud pattern though. Bug eye is somewhere less than 50" I think, don't want to run flares on it.
In reply to Racingsnake :
50" axle width or track width?
RX-7 GSL-SE were 58" axle width because they had 40mm offset wheels. 12A axles were 30mm narrower because they had 25mm offset wheels.
the RX-3 plan was to use an early Ranger rearend, after narrowing the long side to take two short side axles.
Two long side axles used to be the way to convert a Fox body rear to 5 lug wheels. Two short side axles worked out to close to a 50" track width, just right for the Rx-3.
Racingsnake said:In reply to VolvoHeretic :
Volvo rear is definitely a solid contender. I'd want to change to a more common stud pattern though. Bug eye is somewhere less than 50" I think, don't want to run flares on it.
Same Dana 35 out of a Jeep YJ would have the 5x4.5 Mopar pattern, tons of gear ratio options, and shouldn't be hard to find an LSD. Jeep guys basically give them away, too. You would have to narrow it (60.5" width from what I see) and weld on brackets for the 4 link.
I have been looking for a cheap rear end solution to my Volvo 1031 axle's welded-up and re-drilled and .1" out of round lugs, wrong ratio, and no limited slip for 35 years. The cheapest, easiest thing I have found is the Ford Explorer 8.8" which comes in the correct 5x4.5" bolt pattern and 3.73:1 gear ratio w/ a factory limited slip differential and disk brakes from a junkyard which can use the factory axles with a little shortening of one axle housing. Too bad I am so lazy.
According to what I find on the internet, the different weights between the Ford 7.5 and 8.8 is negligible ~ 175lbs?
For your purpose, Dutchman axles has custom 8.8 shafts for $310 per pair in any length and bolt pattern. Dutchman Axles C-Clip Axles
Edit: a V8 Bugeye Sprite sounds dangerous. Especially on stock tires.
In reply to Racingsnake :
What wheels do you intend to use? If you have a big horsepower V8 engine but narrow tires then you can use a MGB rear end. Which is easy to narrow up if too wide.
If you are going to be putting wider tires on and need something to handle it the Dana 44 in an XKE only has a 50 " track. Since that's the same rear end used in the 427 Ford Cobra and countless hot rods it will take anything you can throw at it. It can be found with a 3:54 and posi traction under Jaguar sedans from about 1993 on.
You can take a Jaguar sedan and with a little welding narrow it up It would be easy to mount if you could find an original cage to use. Or just the dimensions. Don't worry about the IRS. Basically a flat plate on top with 4 holes drilled and a bottom mount gets you most of the way. Actually easier than a proper leaf spring set up.
Ford 7.5's can be had in 4-lug or 5-lug flavors, drum or disk brakes, 4 link or 3 link (if you go leaf sprung, the s197's 3-link lower link pickups (for traction bars) and panhard bar mounts may be useful, but those are disk brake and 5 lug), and an aftermarket LSD carrier is about $500 or $600in either clutch type or torsen. A wide range of gearing is available, they typically use the same wheel bearing setups as their 8.8 brethren so 8.8 c clip eliminators should work, and lots of rear brake options.
Only real downside I'd see is that the width might be a bit much for your car.
Racingsnake said:In reply to STM317 :
Thanks, that's good info. Any idea how much your 7.5" weighs?
Not a clue about my specific rear end. But here's a decent list of axle weights (some of which you're considering) that says a stock Ranger 7.5 is ~130lbs.
I'm guessing that narrowing will likely be required for many of the options you're considering, so these weights would only be a starting point.
STM317 said:Racingsnake said:In reply to STM317 :
Thanks, that's good info. Any idea how much your 7.5" weighs?
Not a clue about my specific rear end. But here's a decent list of axle weights (some of which you're considering) that says a stock Ranger 7.5 is ~130lbs.
I'm guessing that narrowing will likely be required for many of the options you're considering, so these weights would only be a starting point.
That's useful info - surprised how little difference there is between the 7.5 and 8.8 weights. It might make sense just to use the 8.8. Any axle would definitely need narrowing, any weight saving there would probably be offset by the extra brackets needed
In reply to Racingsnake :
I'm just guessing here but I suspect any rear end you use is going to be in that weight bracket once it's narrow enough to fit under the fenders.
The advantage of using an IRS is that you can bring the axles into your local driveshaft shop. ( all bigger cities have them ) and have them make 2 much cheaper short driveshafts than machine axles to length and narrow the housing.
Plus installing them is way simpler. Yes some welding skill is called for. But that's what is needed for any rear end.
Finally an IRS takes more than 100 pounds off the rear end. The only thing that is sprung is the rear hubs ( aluminum ) and 1/2 the weight of the axles, lower links. I'm guessing here but a pair of them is probably 35/40 pounds maybe less
bumpsteer said:Ford 7.5's can be had in 4-lug or 5-lug flavors, drum or disk brakes, 4 link or 3 link (if you go leaf sprung, the s197's 3-link lower link pickups (for traction bars) and panhard bar mounts may be useful, but those are disk brake and 5 lug), and an aftermarket LSD carrier is about $500 or $600in either clutch type or torsen. A wide range of gearing is available, they typically use the same wheel bearing setups as their 8.8 brethren so 8.8 c clip eliminators should work, and lots of rear brake options.
Only real downside I'd see is that the width might be a bit much for your car.
TIL that S197s had 7.5s up to 2011. I thought Ford had quit using it after 1993!
frenchyd said:In reply to Racingsnake :
I'm just guessing here but I suspect any rear end you use is going to be in that weight bracket once it's narrow enough to fit under the fenders.
The advantage of using an IRS is that you can bring the axles into your local driveshaft shop. ( all bigger cities have them ) and have them make 2 much cheaper short driveshafts than machine axles to length and narrow the housing.
Plus installing them is way simpler. Yes some welding skill is called for. But that's what is needed for any rear end.
Finally an IRS takes more than 100 pounds off the rear end. The only thing that is sprung is the rear hubs ( aluminum ) and 1/2 the weight of the axles, lower links. I'm guessing here but a pair of them is probably 35/40 pounds maybe less
IRS is much heavier, not lighter, than a solid axle, because of all the extra fomponents involved.
bumpsteer said:they typically use the same wheel bearing setups as their 8.8 brethren so 8.8 c clip eliminators should work
Avoid c-clip eliminators for anything outside drag racing. We tried them on the Ford 7.5 in our (very light) Starlet and they leaked gear oil everywhere and ate the bearings after only a handful of road course laps.
We ended up switching the housing ends to Moser units to use "small" Ford 9" bearings on custom axle shafts. We really only had to go to all the trouble because we accidentally narrowed the housing too far though.
Pete. (l33t FS) said:frenchyd said:In reply to Racingsnake :
I'm just guessing here but I suspect any rear end you use is going to be in that weight bracket once it's narrow enough to fit under the fenders.
The advantage of using an IRS is that you can bring the axles into your local driveshaft shop. ( all bigger cities have them ) and have them make 2 much cheaper short driveshafts than machine axles to length and narrow the housing.
Plus installing them is way simpler. Yes some welding skill is called for. But that's what is needed for any rear end.
Finally an IRS takes more than 100 pounds off the rear end. The only thing that is sprung is the rear hubs ( aluminum ) and 1/2 the weight of the axles, lower links. I'm guessing here but a pair of them is probably 35/40 pounds maybe lessIRS is much heavier, not lighter, than a solid axle, because of all the extra fomponents involved.
Pete;
The center section may be a little heavier but that is rigidly mounted to the car and will do a decent job of helping offset the weight of the V8.
The only sprung items are 1/2 the weight of the axles and 1/2 the weight of the lower links. Plus the aluminum hub.
Where with a straight axle, the whole rear end assembly is sprung. Plus 2/3 the weight of the springs. ( the center is heavier than the ends of springs)
One additional benefit of the older inboard brake assembly type is the weight of the brakes is also rigidly mounted, thus not part of the sprung weight.
You can eliminate the weight of the drag link too by doing what the Cobra kit car guys do. The lower link has a large diameter round tube in the center. If you weld tubes to the other end of the connection Point. You can cut off that heavy tube further reducing the unsprung weight.
The outer shell is not required if you hang the shocks on the body shell. That's only needed to isolate vibration and road noise from the car occupants.
Don't let the mounting scare you. There are real easy ways to figure all of that out without being an engineer.
Ask, I'll walk you through it. I suspect a younger me could mount an IRS in a Saturday afternoon.
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