Forte's

Visit our community sponsor

Thanks Thanks:  0
Likes Likes:  1
Results 1 to 25 of 25

Thread: Rear end question

  1. #1
    Junior Member
    Join Date
    Sep 2015
    Posts
    17
    Post Thanks / Like

    Rear end question

    I have a MKI that was built by someone else. A Chevy rear end was put in the car(just one of many issues I’ve encountered). I recently found a rebuilt rear end out of a 96 Mustang gt. Would this be a correct rear end for my car?

  2. #2
    Senior Member Yama-Bro's Avatar
    Join Date
    Jul 2012
    Location
    Kearney Nebraska
    Posts
    847
    Post Thanks / Like
    Not completely. The FFRs are designed to use a fox body mustang rear axle (87-93), which is 1.50" narrower than the 96 axle you are looking at. The housings are the same between the fox body and the SN95 mustangs, it's just the axle shafts that are different lengths. If you wanted to use the '96 axle you could replace the axle shafts with narrower versions to get it to the correct width. I'm not sure what you'd run into with brakes, you may have to change a bracket to get the calipers to line up properly. Also, you may be able to get the 96" width to work if you have a custom offset to the wheels. That just depends on which wheels you are planning to use.

    I have a lot of detail on my axle build in my build thread including some info on selecting the axle. It starts on post #121.
    Last edited by Yama-Bro; 06-28-2018 at 03:10 PM.
    Started dreaming of a Cobra around 1987
    Purchased Complete Kit 6/9/2017, Delivered 9/4/2017, Rolling Chassis 3/30/2018, Engine Dyno'ed 3/4/2022, Engine installed 8/27/2022
    Click here for my build thread
    Serial #9158
    Design Engineer at BluePrint Engines

  3. #3
    Junior Member
    Join Date
    Sep 2015
    Posts
    17
    Post Thanks / Like
    Ok.
    The builder put the Chevy rear end in with Ford axles. Then he ran Chevy calipers with Chevy rotors and ovaled out the bolt pattern to get the rotors over the Ford axles...so, the SN95 housing with my existing axles and SN95 calipers should work. Possibly. I think I’ll take some measurements and then go and look at the new rear end and make my decision.

  4. #4
    Senior Member Yama-Bro's Avatar
    Join Date
    Jul 2012
    Location
    Kearney Nebraska
    Posts
    847
    Post Thanks / Like
    Quote Originally Posted by Mookie10 View Post
    Ok.
    The builder put the Chevy rear end in with Ford axles. Then he ran Chevy calipers with Chevy rotors and ovaled out the bolt pattern to get the rotors over the Ford axles...so, the SN95 housing with my existing axles and SN95 calipers should work. Possibly. I think I’ll take some measurements and then go and look at the new rear end and make my decision.
    Yikes! Didn't know it was possible to get the Chevy and the Ford axle parts to work together.
    Started dreaming of a Cobra around 1987
    Purchased Complete Kit 6/9/2017, Delivered 9/4/2017, Rolling Chassis 3/30/2018, Engine Dyno'ed 3/4/2022, Engine installed 8/27/2022
    Click here for my build thread
    Serial #9158
    Design Engineer at BluePrint Engines

  5. #5
    Junior Member
    Join Date
    Sep 2015
    Posts
    17
    Post Thanks / Like
    My guess is he used a Ford differential inside the Chevy center...just one of many issues I’ve discovered. My plan is to get the car correct and then sell it and build one myself.

  6. #6
    Senior Member skidd's Avatar
    Join Date
    Jan 2016
    Location
    SA-TX
    Posts
    620
    Post Thanks / Like
    I've heard of using "some" chevy parts in one of these cars. Hey.. I have a Chevy HEI module driving my Duraspark distributor.
    .. but.. mix-matching Chevy parts and Ford parts inside a housing? Though.. It sounds like just ford axles in a chev housing. Either way that's a new-one on me.

    FYI.. I have an SN95 rear end in my (still in gel-coat) Mk4. SN95 axles, and disk brakes. Mustang FR500 17x10.5 rear wheels with 315 Nitto tires (from LMR). F5 3-point and Koni Coilovers all around.
    As of yet, no rubbing. Only 2k miles mind you, and only street driving too. But.. SN95 bits can fit.. key word "can".
    2016 MK4 | '99 Explorer 5.0 | E303&600cfm carb | T5z + 3.55 | 3-link | SN95 | PB/PS | FR500 17" 315&275 |

  7. #7
    Senior Member
    Join Date
    Jan 2016
    Location
    Winnipeg, Manitoba
    Posts
    142
    Post Thanks / Like
    I also have an SN95 Diff in my MK4. I replaced the axles with ones out of a ford ranger which narrowed the width by a total of 1.5" This is accomplished due to the fact that the ranger axles do not have an ABS ring so if you want to use ABS this option would not work. Keep in mind you will probably need to relocate the calipers inward 3/4' each as well.

    North Racecars is a vendor that has the approproate brackets and anything else you need for working with the different Ford axles....not sure about Chevy Hybrid stuff.

    http://www.northracecars.com/VintageBrakes.html

    Good luck

  8. #8
    Junior Member
    Join Date
    Sep 2015
    Posts
    17
    Post Thanks / Like
    Thank you glastron, very helpful.

  9. #9
    Moderator
    Join Date
    Apr 2017
    Location
    Sacramento CA
    Posts
    452
    Post Thanks / Like
    Do you have a pic of the rear cover? How many bolts on the rear cover? Some body did some engineering to put that in there!

    Just curious, if it is working fine, is there an advantage to changing it?
    Mk3.1 347 AFR 205cc Heads A9L EFI siemens deca 60lb injectors MSD 6AL ignition Vortech V-3 3 Link PS/PB

    -- If you can’t fix it with a hammer, you have an electrical problem ! —

  10. #10
    Member
    Join Date
    Aug 2017
    Location
    Ottawa/ON
    Posts
    31
    Post Thanks / Like
    Quote Originally Posted by Yama-Bro View Post
    Not completely. The FFRs are designed to use a fox body mustang rear axle (87-93), which is 1.50" narrower than the 96 axle you are looking at.
    Hey Yama-Bro,

    Would that be any fox body mustang or just the higher performance versions GT etc.? It obviously opens up more options at the Salvage yard if its all of them! :-)

    Dan

  11. #11
    Member
    Join Date
    Aug 2017
    Location
    Ottawa/ON
    Posts
    31
    Post Thanks / Like
    Quote Originally Posted by DanM View Post
    Hey Yama-Bro,

    Would that be any fox body mustang or just the higher performance versions GT etc.? It obviously opens up more options at the Salvage yard if its all of them! :-)

    Dan
    Hey Yama-Bro,

    Forget my last..... I just read you post #121 and it says it all there! Great build thread by the way! I've really enjoyed following your journey!

    Dan

  12. #12
    Junior Member
    Join Date
    Sep 2015
    Posts
    17
    Post Thanks / Like
    Quote Originally Posted by Just puttering View Post
    Do you have a pic of the rear cover? How many bolts on the rear cover? Some body did some engineering to put that in there!

    Just curious, if it is working fine, is there an advantage to changing it?
    It’s a 12 bolt. The main problem is the brakes. Chevy rear means Chevy calipers which do not work correctly with Ford rotors. There is a thin gap between the pads and the rotors causing me to have to give the brake pedal a quick pump before I get good response out of the rear brakes and before I get good feel from the pedal.

  13. #13
    Senior Member CraigS's Avatar
    Join Date
    Feb 2011
    Location
    Blacksburg, Va
    Posts
    4,707
    Post Thanks / Like
    I would do more research on fixing that brake problem. It will be way easier than changing out the axle. The main problem, as you are seeing in the above responses, there is no one model year Mustang axle that has all the right stuff. So, no matter what you get, there will need to be additional $ spent to make it what you want.
    FFR MkII, 408W, Tremec TKO 500, 2015 IRS, DA QA1s, Forte front bar, APE hardtop.

  14. #14
    Moderator
    Join Date
    Apr 2017
    Location
    Sacramento CA
    Posts
    452
    Post Thanks / Like
    I agree with CraigS, also, chevy 12 bolts are a strong differential. Unless it bugs you being a Chevy product? You said it has chevy rotors and also said ford rotors? But it shouldnt be loose just because of having ford rotors! The pads should set the same, ford or chevy??? If you just want to sell, check the cost of this fix compared to the increase in value to sell, it may end up being wasted money!
    Mk3.1 347 AFR 205cc Heads A9L EFI siemens deca 60lb injectors MSD 6AL ignition Vortech V-3 3 Link PS/PB

    -- If you can’t fix it with a hammer, you have an electrical problem ! —

  15. #15
    Senior Member
    Join Date
    Mar 2011
    Location
    Heart of Dixie, Alabama
    Posts
    1,849
    Post Thanks / Like
    Rotor run-out or the axle moving in and out will back the pads up in the calipers.
    20th Anniversary Mk IV, A50XS Coyote, TKO 600, Trunk Drop Box, Trunk Battery Box, Cubby Hole, Seat Heaters, Radiator hanger and shroud.

  16. #16
    Senior Member Yama-Bro's Avatar
    Join Date
    Jul 2012
    Location
    Kearney Nebraska
    Posts
    847
    Post Thanks / Like
    Quote Originally Posted by DanM View Post
    Hey Yama-Bro,

    Forget my last..... I just read you post #121 and it says it all there! Great build thread by the way! I've really enjoyed following your journey!

    Dan
    No prob at all. I'm glad you are enjoying the thread!
    Started dreaming of a Cobra around 1987
    Purchased Complete Kit 6/9/2017, Delivered 9/4/2017, Rolling Chassis 3/30/2018, Engine Dyno'ed 3/4/2022, Engine installed 8/27/2022
    Click here for my build thread
    Serial #9158
    Design Engineer at BluePrint Engines

  17. Likes DanM liked this post
  18. #17
    Junior Member
    Join Date
    Sep 2015
    Posts
    17
    Post Thanks / Like
    Quote Originally Posted by Just puttering View Post
    I agree with CraigS, also, chevy 12 bolts are a strong differential. Unless it bugs you being a Chevy product? You said it has chevy rotors and also said ford rotors? But it shouldnt be loose just because of having ford rotors! The pads should set the same, ford or chevy??? If you just want to sell, check the cost of this fix compared to the increase in value to sell, it may end up being wasted money!
    When I bought the car it had Chevy rotors on the rear with the bolt holes in the rotors ovaled out to fit the ford bolt pattern of the axles. The Chevy rotors had a thickness of 0.998”. I replaced those rotors with Ford rotors that have a thickness of 0.950. I had this work done by a superformance dealer and was not happy with his work or his reaction to problems I encountered after getting the car back, so I’m attempting to get the car correct on my own. I don’t really mind spending a little extra money to get the car correct for whoever buys it.
    Lastly, the pads are backing off after every time I apply the brakes which led me to think it was the difference in rotor thickness and the Chevy calipers.
    I appreciate everyone’s thoughts and opinions and will be checking everything mentioned.

  19. #18
    Moderator
    Join Date
    Apr 2017
    Location
    Sacramento CA
    Posts
    452
    Post Thanks / Like
    If you want to check it, jack up the rear pull a wheel put back two or three lug nuts (no need to be real tight but you may need spacers to hold the rotor tight to the axle) spin the axle by hand and see how tight the pads are. Then step on the brakes and release. Check how tight the pads are, then spin the axle and try moving it in and out and see if you can loosen the pads up by doing this. If you have a posi it will help having both sides off the ground.

    Also, i have no idea but is the center hole of the rotors the same on the chev and ford? They do not center on the studs but the axle

    I am still thinking of how you stuff ford axles in a 12 bolt diff! I will have to see if the part numbers for the bearings are the same for both? They could of welded ford ends on the 12 bolt to use the ford axles. I don't know the spline diameter for the ford and chevy, but the c clips would have to be the same thickness and the buttons on the axle need to be the same. If not you may have to much play in the axles.
    I think stuffing a center section from a ford in a chevy would be no good, no good at all, so are the axles custom or a ford product?
    Mk3.1 347 AFR 205cc Heads A9L EFI siemens deca 60lb injectors MSD 6AL ignition Vortech V-3 3 Link PS/PB

    -- If you can’t fix it with a hammer, you have an electrical problem ! —

  20. #19
    Junior Member
    Join Date
    Sep 2015
    Posts
    17
    Post Thanks / Like
    I will check the things you mentioned and post some pictures. Thanks again

  21. #20
    Senior Member CraigS's Avatar
    Join Date
    Feb 2011
    Location
    Blacksburg, Va
    Posts
    4,707
    Post Thanks / Like
    The thinner rotors are OK. It's only .048 inches thinner and pads wear a lot more than that in normal use. I have no Chev experience but one thought is to check how the parking brake works. If it's built into the caliper, often it is used to adjust the caliper as pads wear. Apply and release the park brake 10 times and see if that helps. A picture of your caliper would help here as someone may recognize what it is from originally and have some tips.
    FFR MkII, 408W, Tremec TKO 500, 2015 IRS, DA QA1s, Forte front bar, APE hardtop.

  22. #21
    Junior Member
    Join Date
    Sep 2015
    Posts
    17
    Post Thanks / Like
    When I got the car it had multiple issues. Under acceleration it would get very squirrelly, the front end would dart back and forth on me. It also took a lot of force on the brake pedal to get the car to stop. I had a 65 Mustang with manual brakes before I got this car it it stopped with much less effort. I took it to the superformance shop and had them put on the Whitby power brake kit and had them investigate the handling issue. It turned out the bolts holding the rear end in place we’re almost all loose causing it to move under acceleration. I got the car back and it seemed much better. The next spring I sent the car back to the same shop to have the rear brakes looked at. This is when I was informed about the Chevy rear in the car and that the bolt holes had been ovaled out(I saw the old rotors). The shop was going to make everything “right”. When I picked the car up they told me the pedal was a little soft and that I should drive it and then bleed the brakes again and it would be good. They also had adjusted the parking brake so applying it wouldn’t do anything (I had left it engaged one time and driven it for several miles). I left the shop happy to have my car back and ready to enjoy it...I got about a mile and I could feel the front brakes were not releasing but actually stopping me if I lifted of the gas. Sent the car back to the shop and when I got the car back was told the rod inside the booster must have moved and had caused the brake to lock up. The shop went out of their way to mention the rod in the booster is set by the factory and should not be adjusted(mentioned it 2 or 3 times). Which leads me to believe they adjusted the rod to get the rears to function properly(when I picked the car up the first time they had said they got the fronts to lock up but not the rears). When I got the car home, I took the wheels off, the pads on the front rotors were on the rotors(no gap but the rotors turned by hand), the rear pads had a gap. You could see daylight between the pad and the rotor. So, that is all the history of the car I can think of and I will get some pictures of the rear end when I get it jacked up and the wheels off. Until then thanks again for all the help and I hope this clears some questions you all may have on how I got to this point.
    Last edited by Mookie10; 07-04-2018 at 03:03 PM.

  23. #22
    Moderator
    Join Date
    Apr 2017
    Location
    Sacramento CA
    Posts
    452
    Post Thanks / Like
    First thing to do, stay away from that shop!
    Mk3.1 347 AFR 205cc Heads A9L EFI siemens deca 60lb injectors MSD 6AL ignition Vortech V-3 3 Link PS/PB

    -- If you can’t fix it with a hammer, you have an electrical problem ! —

  24. #23
    Junior Member
    Join Date
    Sep 2015
    Posts
    17
    Post Thanks / Like
    Haha...yes, lesson learned

  25. #24
    Senior Member CraigS's Avatar
    Join Date
    Feb 2011
    Location
    Blacksburg, Va
    Posts
    4,707
    Post Thanks / Like
    "The shop went out of their way to mention the rod in the booster is set by the factory and should not be adjusted(mentioned it 2 or 3 times)." That is pure BS. Especially on an FFR w/ a mix of parts. While working on Lexus we always at least checked the booster rod length when replacing either booster or MC. If that rod is too long you get what you had-locking up brakes. If it's too short, you have too much freeplay in the brake pedal. The proper process is to measure the rod and measure the MC. There should be somewhere in the range of .020 inch clearance. This is the same theory as having a tiny amount of clearance at the pedal pushrod. We still need a pic of your calipers.
    FFR MkII, 408W, Tremec TKO 500, 2015 IRS, DA QA1s, Forte front bar, APE hardtop.

  26. #25
    Senior Member rich grsc's Avatar
    Join Date
    Feb 2011
    Location
    O'Fallon, MO
    Posts
    3,069
    Post Thanks / Like
    Quote Originally Posted by CraigS View Post
    The thinner rotors are OK. It's only .048 inches thinner and pads wear a lot more than that in normal use. I have no Chev experience but one thought is to check how the parking brake works. If it's built into the caliper, often it is used to adjust the caliper as pads wear. Apply and release the park brake 10 times and see if that helps. A picture of your caliper would help here as someone may recognize what it is from originally and have some tips.
    This is the first thing I'd do.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  

Martin's Dent and Collision Shop

Visit our community sponsor