Front Control Arm Swap - Who has done it, and what were your results?

Topic: Front Control Arm Swap - Who has done it, and what were your results? (Read 8587 times) previous topic - next topic

Front Control Arm Swap - Who has done it, and what were your results?

March 26, 2017, 09:41:12 AM

Thanks to all of your help, I successfully completed my 11" brake upgrade over the weekend, and I love it. While I was at it, I put a set of SN95 springs on the front with adjustable caster/camber plates, and it finally sits at a reasonable level! One side effect, however, is that now under hard braking or a bump in the road, the tires rub on the fender lips, as I have the cobra-r rims that stick out of the fenders just a bit (this has always annoyed me). I'll post some pics once it stops raining.

My mechanic, who is well versed in FoMoCo, suggested that I try swapping to a Fox Mustang front lower control arm, which is slightly shorter, and thus would bring in the tire. I have done some searches on this board, but haven't found much information about if this would work or not. Has anyone tried this, and if so, what were your results?

Thanks!

Front Control Arm Swap - Who has done it, and what were your results?

Reply #1 – March 26, 2017, 10:22:09 AM

It would pull the wheel in 3/4" at the bottom, but you will lose turning radius and mess up the alignment. You do have caster camber plates so you might be able to get it back into alignment.

I'd just get rims that fit.

Front Control Arm Swap - Who has done it, and what were your results?

Reply #2 – March 26, 2017, 12:14:14 PM

Thanks, Haystack. New rims are definitely an option, but I love my rims - I'll have to see if I can find a 4-lug cobra r with different backspacing.

What do you mean by losing turning radius? It seems like our cars' turning radius can't get any worse! Do you mean that these control arms are built with more limited turning radius, or are there clearance/rubbing issues associated with using the mustang control arms on our cars?

Front Control Arm Swap - Who has done it, and what were your results?

Reply #3 – March 26, 2017, 01:39:06 PM

Here is a pic of my TC with Fox Mustang arms and Fox Mustang K, TC springs,17x 8" 225/55 front, 17x9" 255/50 rear Cobra R replicas from OE Wheels and MM CC plates....I've got about 1.5" clearance top of tire to fender lip.... I originally had the TC arms and hated how the wheels stuck out.

Sorry for the large picture.... Uploaded from my phone.
John

Front Control Arm Swap - Who has done it, and what were your results?

Reply #4 – March 26, 2017, 02:24:55 PM

Thanks for the pic and description, John! This is much more the look I am going for. A couple of questions for you;
Do you have any issues with the tires rubbing on the inside fender well when turning?
What are the advantages of a Fox Mustang K member - would I be able to achieve the same results by using my stock k-member by only switching out the Fox Mustang k-member?
Here's how mine looks currently;

Front Control Arm Swap - Who has done it, and what were your results?

Reply #5 – March 26, 2017, 04:32:22 PM

Lol.....thats exactly how mine used to sit.

No scrubbing whatsoever. It did scrub with the longer arms. As for the Mustang K......No real advantage other than being able to modify height easier and availability of aftermarket mounts. It also gave me a little assurance everything works correctly together...Even if it only I'm my mind. I also did it in hope that if I ever go 5 lug.....My wheels will still sit in the fender wells. Tires appropriately sized for the car are getting harder to find so I see myself going 5lug and larger wheels to compensate.

I really don't know what kind of results you will have just swapping arms but It will be better than what you have now. The offset and backspace on the wheels should set the tire closer to proper location.

John

Front Control Arm Swap - Who has done it, and what were your results?

Reply #6 – March 26, 2017, 05:52:01 PM

There is a 10% increase is turning radius between 87- 88 cars and the 83- 86. Largely due to the shorter fox stang length arms. Every time I jump in my 86 after driving my 88 I misjudged parking spots, forgetting it doesn't turn as sharp.

Front Control Arm Swap - Who has done it, and what were your results?

Reply #7 – March 26, 2017, 08:58:59 PM

Great tips! Not digging the turning radius disadvantage, but I think I can live with that more than the tires rubbing on the fenders all the time. I'm really surprised that this topic doesn't come up more on the message boards - unless I'm just searching wrong. I think I'm going to move forward with swapping to the fox mustang arms and see what happens - I'll keep you posted.

Front Control Arm Swap - Who has done it, and what were your results?

Reply #8 – March 27, 2017, 10:03:13 AM

It will suck the bottom of the tires in and create some positive camber. With the CC plate you should be able to compensate for it and get the tires sucked under the sheet metal like you are wanting. The only adverse affect is you are moving the inner lip of the rim inward which when turning the car will put it closer to the subframe. In some cases the rim will come into contact with the control arm or the tire will hit the subframe and you will need steering limiters.

Are the wheels aftermarket or OEM?

Front Control Arm Swap - Who has done it, and what were your results?

Reply #9 – March 27, 2017, 10:40:03 AM

Regardless of OEM or aftermarket........The wheels likely have an offset for a Fox Mustang and not the rediculous front wheel drive offset they used for the T-bird. I would have to look it up but in theory the Mustang offset pushes the wheel outward......A shorter arm will pull it back in very close to original stock position. The only place you need to check for contact issues will be the top lip of the wheel to the strut.. Like you said ...... CC plates will take care of the alignment and if aligned properly you won't have contact.

John

Front Control Arm Swap - Who has done it, and what were your results?

Reply #10 – March 27, 2017, 11:14:43 AM

Appreciate the info but I still would like to know if they are OEM or aftermarket.

Front Control Arm Swap - Who has done it, and what were your results?

Reply #11 – March 27, 2017, 09:37:08 PM

I have the OEM (Ford Racing brand) 4-lug Cobra R's (17" x 8") with 245/45/R17's (see pics). The backspacing (offset?) is huge on these wheels - one of the reasons they stick out so far from the front fender. The catalog says that the backspace is 5.15", with a 15mm offset. It seems like there's 3-4 inches between the rim and the brake caliper. Really hope I don't need those steering limiters. Seems as though every mod I do requires an additional 5 mods to make it work - feels like I'm going to end up with a Mustang when it's all said and done! lol - this all started with wanting better brakes...

I'm now really glad I sprang for the CC plates, everyone is right about them being a must-have when you start messing with springs/control arms, etc. After just changing to the mustang spindles my alignment was crazy bad. I have to say though, all this work seems worth it - even though I'm not well aligned yet, the handling with struts and springs from a SN95 Mustang do wonders for these cars - literally feels like a different car! (Doesn't help that one of my struts was COMPLETELY dead.)

Front Control Arm Swap - Who has done it, and what were your results?

Reply #12 – March 28, 2017, 02:05:50 AM

When I had 235/60's on mustang 10 holes on my 87 bird the tire was less then a finger width from the strut. The 275/60's would rub really hard on the strut. This was all stock junk though. I beleive the 11" spindle pushes stuff out a hair.

Front Control Arm Swap - Who has done it, and what were your results?

Reply #13 – March 28, 2017, 12:52:02 PM

So lets get some base wheel measurements so we can start talking geometry. The factory 15" x 7" 10 holes for the Birds and Cougars had a 5" backspacing with a 25mm offset and the 87-88 16"x 7" TC Snowflakes had a 5.25" backspace with a 31.7mm offset. Now I have no idea what the stock size tire was on the ten holes but I do know that the Snowflakes came factor with 225/60/16's Goodyear VR Gatorbacks. Also wanted to clear up that there were only three years of the Cobra R and they were in 93, 95, and 2000 of which the OP's wheels are styled after the 1995 Cobra R.

The whole exercise here is to see where the current wheel/tire combo is in relation to the factory wheel/tire combo for clearance reasons. Being that the OP changed to the 11" front brake setup and the TC's had this setup we will use the Snowflake wheel the associated stock tire that went with it to compare to the OP's current setup.

If you do a side by side comparison of the Snowflake wheel/tire combo to the OP's "1995 Cobra R" replica wheel/tire combo to the Snowflake wheels you will see that the difference are as follows:

1995 Cobra R Replica
Tire Height - 25.7"
BackSpace - 5.1"
Offset - 15mm (0.6")
Width of Tire at Sidewalls - 9.6"

Snowflake
Tire Height - 26.6"
BackSpace - 5.3"
Offset - 33mm (1.3")
Width of Tire at Sidewalls - 8.9"

I got all of this by inputting the known data at this site - https://www.rimsntires.com/specspro.jsp

So what this gets you is that from where the back of the wheel hub mounts to the rotor face to the inside wall of the tire the Snowflake combo measures (Offset + 1/2*Width of Tire at Sidewalls) 5.75". The 1995 Cobra R Replica combo measures 5.4". With that you can see that the inside wall of the 1995 Cobra R Replica combo tire is 0.35" further away from the strut than the stock Snowflake combo.

Now lets think geometry and say that the control arm is parallel to the ground and the strut is the hypotenuse thus giving us a 90 degree triangle. Lets further assume that where the tire would contact the strut is about in the middle. Quick math tells me that if I install the Fox control arm i.e. shorten the control arm 0.75" that the inside wall of the tire will move in about half that distance or a little more (draw a triangle with the strut as the hypotenuse and the control arm as the bottom leg and you will see it). So let's call it 0.5" just to be on the safe side.

With that the actual distance the inside wall of the tire will move toward the strut is about 0.15" or about 5/32".

So to the OP, if you currently have 3/8" clearance between the inside wall of your tire to the strut my guess is that it will clear if a Fox lower control arm is installed. I would definitely put pencil to paper and take a few measurements before I did it but my confidence level is really high that it will work.

Front Control Arm Swap - Who has done it, and what were your results?

Reply #14 – March 28, 2017, 07:09:54 PM

I did this same upgrade last year. Braking greatly improved, but I'm experiencing the same issue as the O.P.. Is it possible to find a wheel that the offset is better? Just curious as I'm thinking of changing wheels. I currently have 17×8 Saleen SC replicas(can't remember offset at the moment)