Rear brakes on complete kit question

[Fbird]

Hi there. I have my panels in place after bleeding my brake lines on my complete kit. After being bled the fronts seem to lock up nicely and release. The rears seem to be in a perpetual lock after doing this. They actually can be rotated, but they require a heck of a lot of force. The parking brake is not on. Is this because they are self adjusting and without being able to drive and move they have not adjusted yet properly? I am still on jack stands. Nothing in the manual about this?

Thank you.

[edwardb]

a) Not normal, b) More details about what brakes you're talking about. Depending on the brakes, the e-brake may need adjusting (self-adjusting or otherwise) but the regular brakes should work normally after bleeding. There will be slight drag of the disk against the pads. But for the rears, where you're also rotating the diff, it's sometimes hard to tell. But what you're describing doesn't sound right.

[Papa]

Is the brake pedal resting on the frame in the foot box? If so, it's possible that the brakes aren't fully releasing. The pedal should fully relax without contacting the frame. You may need to shorten the master cylinder push rods a small amount.


https://www.youtube.com/watch?v=_JKTn6t6aoU

[Fbird]

Hi there Sir. Here is what I got. Here is a link to a video showing exactly what and how they function. I loosened up my e brake and that helped. It is still pretty tough to turn in my opinion. There is no obstruction in the pedal travel preventing it from releasing. I am using parts supplied by factory five. The diff is a freshly rebuilt 87 mustang 3.55 gear with no oil yet. That could be a factor. The hydraulics seem to be working. Check this out and let me know what you think. I am thinking it needs to break
https://youtu.be/nemh2ztuOn0
https://youtu.be/nemh2ztuOn0
Hope all are safe. This project is helping me keep my sanity.

[Fbird]

Thanks Papa for the video. I think my travel looks good so at least that is eliminated. My coupe doesn’t seem to have the brace in it that was shown. It is wide open in my foot box. I posted a video showing more if you care to look. It is my first video to share ..I am learning.Thanks. Stay safe in this surreal time.https://youtu.be/nemh2ztuOn0

[Papa]

Thanks Papa for the video. I think my travel looks good so at least that is eliminated. My coupe doesn’t seem to have the brace in it that was shown. It is wide open in my foot box. I posted a video showing more if you care to look. It is my first video to share ..I am learning.Thanks. Stay safe in this surreal time.https://youtu.be/nemh2ztuOn0

Sorry, I missed the fact that you are building a Coupe. After looking at your video, I'm not convinced you have an issue. Turning the rear diff without fluid with new pads … seems like it turned with some friction, but not like it wasn't releasing. I'll defer to the experts for their thoughts. My rear brakes squealed a bit until I started actually driving the car and now they are nice and quiet.

Dave

[GoDadGo]

https://youtu.be/nemh2ztuOn0

Keep in mind that when you are rotating one of the front hubs, you are only dealing with one bearing and one brake.
When you are rotating the rear, you are rotating the majority of the assembly and if you have a clutch pack posi, then both axles are likely turning.
If it is an open rear end, then you are still moving the spyder gears around which is also additional friction.
Either rear end style will create a lot more friction compared to spinning one of the front hubs.
Personally I think you are A-Okay to proceed.

[edwardb]

I agree after looking at the video that it's maybe OK. Diff, clutch packs, etc. add some drag as others have mentioned and I also did in my first response. Also the disk pads will drag slightly when released, which also is normal. I suspect your fronts will drag a little more than they are now when broken in.

[Alphamacaroon]

Mine is the same way and it surprised me at first, but I thought this was common with positrack/limited slip? My understanding is that in a standard diff you would never notice this friction because none of the turning motion would make it to the drive shaft— it's all transferred to the other wheel and it just freely turns (even if the car is in gear). But when you have a limited slip, any movement of a wheel is now connected to the drive shaft. And since the drive shaft turns 3+ turns for every turn of the wheel it's like starting to pedal a bike in high gear— it requires much more force to overcome any friction and resting inertia in the system which not only includes the differential, but now the drive shaft, and parts of the transmission. Anyway, I could be totally wrong, but from what I know about limited slip and gear ratios it makes logical sense to me.

Certainly one way you could be totally sure is to just remove the pads and see if changes. I suspect it might be ever so slightly easier to turn, but not much. At least that way you know it's not the brakes.

[Fbird]

Thanks all. I was leaning towards it being ok, but I am not an expert. All the brakes I have done in the past were much less drag. I also have never had any experience with a newly rebuilt limited slip before either. I left that to the experts so that should be good. I appreciate all the feedback. I am in process of laying in sound suppression materials and getting ready to try covering a dash. I also found a used 2015 mustang 5.0 near me with 40000 miles in my budget. Yeah!