New member with lots of dumb questions

[Wolffbone]

Proud owner of FFR MK3 Cobra with some issues most pressing are hard brake pedal that wont stop car and hard rubbing drivers rear tire.....275x60x15bf goodrich radial ta tires chrome shocks adjusted with 1 5/8 of threads already showing and a ride height over 7 ii already. Thanks for any input Proud to be a member and owner. Have already found you need to leave a little extra time anytime you go somewhere for pics and questions

[GoDadGo]

Wolfbone,

Normally you've got to have a certain number of posts before you can post pictures.
Reach out to David Hodgkins (System Administrator) and see if he can help you out.

Steve

[iowa]

hello
i'm a new member as well w/a question
i have a 9" rear end i had intended to
install in my '65 hipo mustang
would this fit in the MK4 roadster?
thanks
iowa

[edwardb]

hello
i'm a new member as well w/a question
i have a 9" rear end i had intended to
install in my '65 hipo mustang
would this fit in the MK4 roadster?
thanks
iowa

Suggest starting a new thread with your question rather than going off topic on someone else's. Forum etiquette plus you'll get more/better responses.

[Indy Shu]

Proud owner of FFR MK3 Cobra with some issues most pressing are hard brake pedal that wont stop car and hard rubbing drivers rear tire.....275x60x15bf goodrich radial ta tires chrome shocks adjusted with 1 5/8 of threads already showing and a ride height over 7 ii already. Thanks for any input Proud to be a member and owner. Have already found you need to leave a little extra time anytime you go somewhere for pics and questions

Wolfbone,
Congrats and welcome!
Not much to go on here. For the brakes, disc all around? power assist? To what degree "won't stop car"? Start with some very basic stuff. Are all the rotors shiny, so at least functioning. Since car is new to you, i would take a look at all the brake pads and likely replace with a known quality pad. See if that makes a difference and diagnose from there.
For the tires, i think that size is almost 2 1/2" taller than the recommended sizes. Do you have the same tall tires on the front? i think just about anyone would recommend getting proper fitting wheels/tires and get to proper ride height. Most also have 295's or 315's in rear. Is there something that prevented builder from going wider in back? Maybe a wider rear end? Did you get a build manual with the car? if not, you may want to get your hands on one for lots of info and specs. (I think i may have a spare)
Keep asking questions. Good luck!

[iowa]

sorry, i did start my new thread
thanks
iowa

[Ray]

The OP appears to be in the Washington DC area (based on the IP address.) Don't know if anyone is nearby that could help him out or not. I have sent him a PM suggesting that he update his profile to show his general location.

Ray

[AC Bill]

Congrats on your new car! Get it set up correctly and you should love it.

The rear tires size should work fine, as many owners running 15" tires have used them without issue.
The builder may have used a later model donor Mustang rear end. They were wider then the earlier Fox body rears. That may cause the tires to rub, as they stick out further. You could measure it to find out, unless the builder can inform you.
The incorrect wheel offset may further complicate matters. A little to much negative offset will push the tires out further This can be tricky because depending on the brakes used. To much positive offset, which will bring your tire more inside the wheel opening, can also mean that your wheel may rub the calipers, or contact other suspension components.

Seven inches of ride height is absurd. Is that measured from the bottom of the tube frame, to a level ground surface? The previous owner must have done that to try and lessen wheel rub, but it must look pretty strange, and handling is likely compromised.

You really need to provide more details about the roadsters set up, measurements, spring rates, suspension, brakes, IE 3-link, IRS, etc, least until you can add some photo's.

[Wolffbone]

Ray tried to update profile
said i dont have access to that area

[Wolffbone]

Thanks for the input Indy Shu for reply . I'm from Cincinnati my car has 1995 Mustang rotors all around with disc brakes front and rear. not sure if the donor master cylinder was from an original power brake car as I'm kinda overwelmed now with so many small issues with car trying to put out small fires to build confidence to move forward with larger problems. The car now has manual brakes with no booster at all. It has a proportioning valve. I was messing with proportioning valve it was at start out 4 turns went to 6 out an 8 out while hard braking then turned all the way in and then two turns out , all while braking in gravel only front brakes barely tried to lock in gravel lot , and i was standing on them with strong legs

[Wolffbone]

Indy Shu , as for tires not sure what prompted size selection may want to stay with bf goodrich for retro look....not sure. The fronts are 235 60 15 seem to have made light contact they have a .500 spacer between rotor and wheel . ride height in front is around 4 inches. had car on jack dropped when i checked rear ride height and got 7 inches after driving car it settled to 6 1/4 which is still high for a difference of approx 2 1/4....front to rear....about oversize of tires.

[Wolffbone]

ray how can i add city and pic to profile

[Wolffbone]

thanks for trying to help AC Bill the rear end came from 1995 mustang i was told with Chrome shocks with adjuster and locking ring not a set screw, not sure of spring rate. It has straight axle all stock 1995 mustang brake components

[Wolffbone]

AC Bill the ride height was after letting down off jack....yesterday took out for a spin rechecked settled to 6 1/4 which is still high as i believe you try and achieve 4.5 inches

[Wolffbone]

Indy Shu also appears that they ground the arm on the caliper frame down to clear the wheel as there is only 1/8 inch between wheel and caliper arm

[Wolffbone]

Indy shu the wheels are american racing 5 spoke

[Wolffbone]

ray can i get activated

[Ray]

ray can i get activated

With the required number of posts the system should activate automatically.

To add items to your profile head to “my profile” in the top blue bar and pop open “customize”.

Ray

[AC Bill]

Ok so you do have the wider rear end. Some fellows changed the rear axles to make it narrower, to match the 87-93 Fox body Mustangs, so they could run wider wheels and tires. So that is one work around. A different profile tire is another choice, the 275-50R15 for example.
I think the fact that you have 1/2" spacers on the front wheels, means the wheel backspace may have been an issue. Perhaps it causing the wheel to rub the calipers, so the builder added the spacers to move the wheels outward to gain more clearance. Even shorter axles may be an issue if the rear tires have the wrong backspace.

Yes the 6-1/4" ride height is a bit on the high side still. Ideally the car is best with a slightly lower stance, but as mentioned, the 275-60R15 is almost 2" taller sidewall then the 235-60R15's. If they can't be tucked in further, you may not have a choice.
When FFR brought out the MK3.1 model, widening the rear wheel openings was one of it's improved features. I think they did this because more builders were using the later model (94-up) Mustangs with the wider rear ends.

In this older thread, Maximum 15" Tire Sizes for roadsters were shown as, Front Tire Sizes 235/60R15 Rear Tire Sizes 275/50R15

https://thefactoryfiveforum.com/showthread.php?1869-Wheel-amp-Tire-Specifications-Roadsters-and-Type-65-Coupes

[Jeff Kleiner]

As for the tire rub you have at least two, likely three things working against you.


...275x60x15bf goodrich radial ta tires...
1. Rear tires that are too tall


...the rear end came from 1995 mustang...
2. A rear axle that is too wide


..the wheels are american racing 5 spoke....
3. It's very likely that these wheels have the wrong offset and backspace, especially given the fact that they had to use a pretty significant spacer in the front.

As for the poor braking my bet is that when the booster was eliminated the builder failed to do the pedal modification to change it to the proper leverage.

Good luck,
Jeff

[Wolffbone]

Thanks for the help AC Bill can't find a 275 50 15 tire to match the be Goodrich fronts may have to change all four my OCD would self ignite having different rears as well as any judges at a show...lol.....will pull wheels and measure rear end width as well as off set.....the previous owner did have interference issues on fronts with wheel to caliper.....

[Wolffbone]

Jeff I will do more homework Monday getting a feel for what's going on not a lemon just not as finished as I thought

[Wolffbone]

Thanks for all the help so far guys just checked more on brake issues found that caliper pistons are single 1 1/2" the pedal is 13"from middle of pedal to middle of pivot and 3.5" from middle of pushrod to middle of pivot for an approx ratio of 3.7 if my math is right an think for manual brakes calls for 6.5 so again not sure on my math but think adding 1.5" would give me approx 6.5 ratio so do I move my piston rod up or down from current location

[Wolffbone]

Also not sure how to ask questions on forums

[Jeff Kleiner]

I got your Private Message RE: Pedal mod. I have a cut & welded pedal from a SN95 pedal box that came in a box of parts that were included with a Mk3 that a customer to brought me to finish a few years ago. He ultimately decided on power brakes so this modified pedal was not used. Center to center on it measures 2.375". I'm not sure what the dimension is supposed to be for modified (don't have a Mk3 manual handy and any cars that I've built using a Mustang box have gotten power brakes) but if you'd like to have this one I'll be happy to send it to you. Just understand that I did not weld it and although it looks good I can not/will not guarantee it's integrity.

Jeff

[Wolffbone]

Thanks Jeff just seen your post as I have been battling food poisoning have kind of been in and out of it.......would definitely use the pedal I am a welder by trade but that would be a start before I modify mine and I may return favor and modify mine to same for another how much would you like for it I am in Cincinnati ohio

[Wolffbone]

Figured out how to post new thread finally