7.5" rear question

Topic: 7.5" rear question (Read 2645 times) previous topic - next topic

7.5" rear question

October 21, 2005, 09:00:22 PM

Hey all,

I am looking to buy a 1983-86 7.5" Turbo Coupe differential from a person on the Lincoln Mark VII side of the Internet. :) Anyway, he says it is a 7.5 with "#T 54" as the gear code...is that a 7.5" axle with a trac lok and a 3.45:1 gear? I am checking to make sure the unit is on an axle with drum brakes (i.e. not an 8.8 with discs) but you guys know of any other tricks to make sure this is the part I want???

BTW, this is for my 1983 Continental, which has a 7.5" and which I have no interest converting to an 8.8. The time is coming for me to put a EFI 331 stroker in it, and I just need to lose the open rear.

7.5" rear question

Reply #1 – October 21, 2005, 10:30:40 PM

1983-86 turbo coupes had a 7.5 rear w/3.45 gear all were traction lock also.

v-6 and v-8 cars recived 2.73-3.08s some special ordered 3.45's most all were open diffs

7.5" rear question

Reply #2 – October 21, 2005, 10:44:45 PM

Where die he get these nunmers??? They are just a bunch of mombo-jumbo. There is(orignally) a tag on one of the rear cover bolts that has the model info as well as ratio, size, and build date. There is no ID info on the housing. AS a FYI the to the best of my knowledge a 7.5" 3.45 T-lock was the only rear available in the '86-earlier TCs..

That said I wouldn't even consider using a 7.5" behind a 331...

7.5" rear question

Reply #3 – October 22, 2005, 01:09:02 AM

they also have quad shock brackets

7.5" rear question

Reply #4 – October 22, 2005, 03:17:35 PM

Quote from: TurboCoupe50

Where die he get these nunmers??? They are just a bunch of mombo-jumbo. There is(orignally) a tag on one of the rear cover bolts that has the model info as well as ratio, size, and build date. There is no ID info on the housing. AS a FYI the to the best of my knowledge a 7.5" 3.45 T-lock was the only rear available in the '86-earlier TCs..

That said I wouldn't even consider using a 7.5" behind a 331...

The car (whenever I get to it) will never see drag radials, much less slicks when it goes to the track. Donno what kind of power the 331 will make, but it'll be pretty mild because I am going for a real Lincolny-feel with this car. The car already has rear discs and the 7.5 is adequate for what I need.

Anyway, I'll see what his reply is to my email. If it isnt what I think it is I'll pass. No biggie.

7.5" rear question

Reply #5 – October 23, 2005, 10:26:33 AM

I had a 7.5" rear behind a nearly stock HO engine and it lasted about 8 months before it started clunking and whining. Near the end, you could put your foot on the top of one of the rear tires and push and you could hear the c-clips bouncing off the carrier. Swapping to an 8.8, at least in the t-bird/cougar is cake, it's a direct bolt in. It will also allow you to bolt on 15x7 wheels with 5.5" back spacing with 275/50R15 with no clearance issues or fender lip rolling(assuming it's from a stang).

I don't care how mild you build that 331, even a well prepped 7.5" rear will have a short life span behind it.

7.5" rear question

Reply #6 – October 23, 2005, 11:52:53 AM

Eh, my 7.5 in Darkthunder is holding on strong. The 8.8 in the TCR is making some questionable noises. Obviously it depends on the care and abuse. If you don't give a you can kill any rear end.

7.5" rear question

Reply #7 – October 23, 2005, 06:42:32 PM

Its a Lincoln, its gonna be driven pretty lightly. I just need to make two rubber marks down the road when I wanna light up the whitewalls or 17" Cobras. I've heard of 7.5s running 13s consistantly in early 80s Mustangs, it'll run fine behind my 331 and street driven whitewalls.

7.5" rear question

Reply #8 – October 24, 2005, 05:34:00 PM

I've broke 2 7.5's in my bone stock 86 TC, I just dont drop the clutch at 4500 rpms any more and it's doing fine. Running an auto should be even easier on yer rear.

7.5" rear question

Reply #9 – October 24, 2005, 07:16:48 PM

Don't say that I didn't warn you.

7.5" rear question

Reply #10 – October 25, 2005, 09:31:04 PM

Well the guy had a 7.5 T-loc with a 3.45...I'm buying it.

If it breaks, its my bad. Thank you everyone for your advice.

7.5" rear question

Reply #11 – October 25, 2005, 09:50:22 PM

ill hopefully be picking one up too

7.5" rear question

Reply #12 – October 25, 2005, 11:45:39 PM

i think youl be alright as specially with regular radials. the 7.5 is not THAT bad. if the car isnt constantly abused you should be good. depending on the output of the 331 anyway. the linc is heavy so i wouldnt go too nuts. id start thinking of upping to an 8.8 if you get a higher stall converter/shift kit in there and decent sticky tires.

7.5" rear question

Reply #13 – October 26, 2005, 07:04:17 PM

Its gonna be a real mild 331, and if it breaks, I'll bite the bullet and swap a Mark VII rear in...but its already got the huge 11" rear discs so I would prefer not to.

Ok, so who knows which speedo gear to use with 3.45 rear? Gotta use a 3.55?My initial google searches haven't come up with jack.

7.5" rear question

Reply #14 – October 26, 2005, 07:10:40 PM

Nevermind, I found a good one. This might help Tbird232ci too...might wanna print this out. :)

http://users3.ev1.net/~walsted/speedogears.html