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MG MGB GT V8 Factory Originals Technical - Ford 7.5' rear end?
|Have any of you tried or heard of using a Ford 7.5" rear alxe?? These are used in a WIDE variety of Ford, even V8 ones. The reason I ask is that I haveone sitting in the garage with gears that will work ok in the car. That will let me use the bigger 8.8 for another V8 project (much higher power) I hope to do in about a year.|
|Larry, while everyone seems to think, most are changed out before they break. I think for a light car without slicks, it would last just fine. That being said, I don't think I would spend the money having one narrowed. There are just too many better options that would cost about the same by the time you are done...give or take a C-note.|
P.S. I am about to put a 7.5 in my Merkur...just keeping the IRS. Another story all together!
|I have some experience with the ford 7.5 rear end and know that it can handle over 200 hp and not break. This rear end is the preferred rear end to use for many dirt track racers. I have thought of using it in an mgb but havenít yet. One of the most respected names in modified ford 7.5 rear ends is Scott Spangler with Chesapeake Machine 704-484-0413 http://www.cmperformanceproducts.com |
He should be able to help you with application questions and even building a rear end to fit your mgb if needed.
Hope this helps.
|The reason I posed this questionis that I have a 7.5 siting. Narrowing is a matter of staying after work for a few nights with one of the machinists, then $110 for getting the shafts shortened and splined. So for me it is much cheaper to use what I have. I know there is a guy that has one in a 460 powered fairmont and het got 100+ drag runs on his before it failed. I will check with scott though to see what he recommends. I also have a 8.8u but I would like to save that for use in a track oriented car. The Vert I am working on now will be more a daily driver type car.|
THanks guys!! I thinkI will go with the 7.5!! now I just need to scrounge up a posi for it.
|I believe my old '83 Mustang GT had a 7.5 in it with the stock frame bars. I drove it rather hard going through a set of rear tires every 10~15K miles. The posi-unit eventually locked up at 115K miles. I'd say the 8.8 is stronger but the 7.5 should do fine for a 2400lb car.|
|I had a 79 Mustang 2 door that came with a 2.8 V6 and a SROD manual trans. I built up a 351 Windsor and C4 trans, but left in the 7.5 open rear with 3.45:1 gears (106,000 miles) with 205-70RX14 tires. Never got it to hook up (thank goodness) but it was still going strong after 2 years when I sold it to get my 73 Roadster. It seemed to be pretty tough.|
|Aside from more gear choices and a posi, is the 7.5 really any stronger than the MGB rearend? Is it any lighter?|
|I would think it is much stronger, given that it is made for bigger heavier cars with larger engines?? Weight + power = high stress. It is completely obvious that the stock MGB rear is not up to containing my old 302 which could not put out 290hp at the crank. The new build is looking to 350hp. I have talked to guy with Full sized Ford fairmont, running BB fords into the 11's in the 1/4mi with a stock 7.5" Ford rear. That is good enough for me...|
The weak point of the of the MGB rear is not the shafts, or housing, it is the spider gears IN the diff as well as the spider gear shaft. I have heard reports that MGB race cars had a special solid pin in place of the stock roll pin. Ford uses a solid "bolt" to hold thier spider gear shafts in place..
Been doin' some "Internet Research". Found this little nugget over at coolcats.net:
<<Most Ford owners look down upon the 7.5" rear but it is a fairly tough unit. People have used them in 12-second cars without problems, and they're not nearly as weak as people make them out to be. If you're thinking about upgrading your 7.5" economically, you shouldn't have any reservations so long as you're not drag-racing heavily. The 7.5" rear is about 80 lbs. lighter than a comparable 8.8" rear.>>
|Carl, great info!|
One note, is that our cars are a good bit lighter than most cars the 7.5 is used in, that helps longevity as does the limited tire sizing of a mgb. Torque+ Mass + traction = broken drivetrain. It is much the same as the issue with the T5, the F-body guys hate them because they break easy, but I have yet to hear a MG driver blow one up.
I may be wrong but I have allways been under the assumption that the biggest problem is not the torque to traction but when our cars hook up after the wheels start to spin. The shock when they finally grab hold.
Anyone else have knowledge on this?
|that could be also garret. I guess I will be the guinea big as usual!! I have info from a guy running a 460 in a fairmont and he got 100+ hard 11second passes out of a 7.5 before it blew. THat tells me it can handle what I will be doing, at least with the road car. This way I can save the 8.8 for the track car.|
|Larry which car should I look for to find a 7.5 rear to shorten for my MGBV8. I also would like 3.27 gears and locking rear. I have the Rover 3.9 and Rover .82 fifth gear trans. Thank you for any help. Denny.|
|Well almost any Ford from the 80's will have either a 8.8 or a 7.5 They are hard to tell appart actually. I got this 7.5 by mistake when trying to get myself another 8.8 Most of the 80's Tbird will have this rear end. The gear ratio you are looking for might be an issue. Mine is a 2.73, and all I ever see on ebay is 3.73 and 4.10 sets, but I am sure they are out there. Lockers can be had from Ford Rangers of the same vintage. Maybe just getting a Ranger rear end from the start would be a better option? I just don't know what gearing they will have.|
I will check my newly arrive "big boy toys" catalog to see if they list gear sets for the 7.5 and let you know.
|Nationaldrivetrain.com lists various ratios for the 7.5 for $155. http://nationaldrivetrain.com/shopsite_sc/store/html/page54.html |
|<<They are hard to tell appart actually. >>|
Study the rear covers carefully. The left & right sides of a 7.5 cover are more rounded ( ) vs the 8.8 which is more like a square with rounded off corners.
This thread was discussed between 15/02/2004 and 24/02/2004
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