Rear coil-overs for Cobra with Mustang 8.8 four link

[donraye]

Hi everyone, I just finished my cars first ever real world cruise and it was mostly good news BUT: I have one big problem in the rear suspension area that has to be addressed right away.
I have a stock Mustang 4 link rear with a 8.8" posi. The car has tire rub in a huge way and I need to raise the rear at least 1/2" to cure the problem. As it is now every time the road has a little dip in it the rear wheels contact the wheel wells at about the
10:O'Clock position. It is truly bad on the left side which I think is just due the slight difference in wheel well contours due to the mold used for the body not being exactly symetrical.
Also the car rides so f@#%ing harsh that it just about jars your teeth out when you hit any kind of roadway imperfection from a little pothole patch job to even freeway expansion joints, etc. They are all met with a SHARP whack/jolt and the ride quality truly sucks! I think that is also due to the use of the way too stiff Mustang springs.
The bottom line is I need to get the standard Mustang suspension converted to an ajustable height coil over set up with the correct springs for the weight of the car.
I do not race or use the car in any competitive events so it does not need to be "the" best out there, and afordability is a consideration. Does anyone have any ideas on what/who's conversion kit is good and good value for this application and is a "bolt in" rather than a "weld in" job?
I've been looking at a couple of kits for mustang rear conversions from "Competition Engineering" that seem like they might be a good choice. Anyone have experiences along these lines?
Thanks, Don

[Clois Harlan]

I have gone through this before and what you need to do is take one of your shocks off an measure the colapsed length and then measure the extended length. Also, determine what type of top fastner will be required for the top of your shock (stud type or the type that requires a bolt to pass thru an heim joint or just a rubber bushing.

A good choice would be something like a HAL or Carrera and they are reasonably priced. I am guessing but you probably need something that extends between 14" compressed and 21" extended. Also, you will probably want a spring rate of about 250#-300#. You can softern this up with the adjustable dampner that is available on some models of coil overs.

Clois

[nevermind65]

QA1 makes a kit to replace the springs and shocks on a factory style Mustang rear set-up. I had these on a Cobra I sold and they work really nice. You can get the springs in just about any rate you want, and they are relatively easy to find so if you think it is too soft/hard, you can buy another set easily.

I had the 12 way adjustable, but now they make a 24 way adjustable. I found mine on RacingJunk.com, but have seen many on Ebay. I did have to use a slightly different lower mount as the factory version wasn't strong enough. Basically, I just copied the factory version but made it out of 1/4" plate steel.

Good luck.

[jams]

I went with the QA1 shocks because I had the same problem. Very pleased with the results.

[strictlypersonl]

It seems to me that there are two problems here: Bad ride, which can only be fixed with a spring/damper change, and a tire-clearance problem which can only properly be fixed with a wheel offset/width change or a tire change. Changing the ride height to "fix" the latter problem puts you in the position of changing the basic suspension geometry, usually to its detriment.

[Clois Harlan]

Don,

First you have a beautiful car.

I went back and looked at your photo gallery and you are not running anything so wide you would be creating your own problem. It looks as though you are probably running some 8" wide rims all the way around with maybe some 235 X 15 front and 255 X 15 rear.

Your offset/Back Space doesn't seem to be creating your problem either. I assumed you were talking about the rear tires rubbing on the outside of the tire and NOT the inside. I think the Hal (QA-1) shocks will solve your problem if you just need to pick the rearend up a little. Your Mustange springs JUST may be to soft for your car.

Clois

[donraye]

Originally Posted by strictlypersonl

It seems to me that there are two problems here: Bad ride, which can only be fixed with a spring/damper change, and a tire-clearance problem which can only properly be fixed with a wheel offset/width change or a tire change. Changing the ride height to "fix" the latter problem puts you in the position of changing the basic suspension geometry, usually to its detriment.

Thanks for the thought of that approach to the problem but the wheel offset I am using in a very high 45mm and it does not matter what width tires I am using as the is no "deep dish" to the rear rims and I have plenty of room to the inboard/set back side You can not get any wheels with less outboard/dish extension as these are almost flat/flush on the outboard side. In fact it rubed just a s bad with 235s on it as it does with the 285s on there now.
I would have to change the entire rear end and go with some narrowed unit of something else entirely like IRS. All that is WAY expensive and complicated. I'll try some of the coil-over approaces offered above.

[nevermind65]

I didn't realize you had a StreetBeast. I had a CMC when I put on the QA1 coilovers. I bought a set of FFR upper and lower rear control arms and removed the spring mount on the frame and the lower control arm. Then I mounted the coilovers about 2-3" further toward the center on the axle. After doing this, I was able to put a 315 series tire on the rear without rubbing.

[CobraEd]

Shocks that are too firm cause a very harsh ride. Springs that are too firm cause a very firm ride but never harsh. Also, your shocks may be bottoming out when compressed. Check the length.

Where are your bumpers ?????

.

[donraye]

Originally Posted by Clois Harlan

Don,

First you have a beautiful car.

I went back and looked at your photo gallery and you are not running anything so wide you would be creating your own problem. It looks as though you are probably running some 8" wide rims all the way around with maybe some 235 X 15 front and 255 X 15 rear.

Your offset/Back Space doesn't seem to be creating your problem either. I assumed you were talking about the rear tires rubbing on the outside of the tire and NOT the inside. I think the Hal (QA-1) shocks will solve your problem if you just need to pick the rearend up a little. Your Mustange springs JUST may be to soft for your car.

Clois

Thanks Clois, The wheels are 17" not 15" and the tire profile in back is 40.
I have changed the wheels since the photo you viewed but the new "real" Halibrand Cobra III wheels have an even higher offset and are as flat a profile on the outboard side as it gets so they are not the problem as the wheels rubed just as badly with the "weird" wheels that you saw in the photos (which were on the 90% finished car when I purchased it).
I think the Hal QA-1 are what I'll be looking at as you and others have suggested. The rear offset is 45 on the Halibrands and they are 9" rims running 285s in back. Does anyone out there know about the "Competition Engineering" Mustang conversion units I looked at?

[nevermind65]

Is this what you were looking at?

http://www.competitionengineering.co...?CatCode=10035

If so, you really wouldn't need this with the QA1 set-up. They literally bolt right in place. The only issue may be the lower mount is a little weak, but I believe you can buy a stronger one for only a few bucks.

[donraye]

Originally Posted by CobraEd

Shocks that are too firm cause a very harsh ride. Springs that are too firm cause a very firm ride but never harsh. Also, your shocks may be bottoming out when compressed. Check the length.

Where are your bumpers ?????

.

I Do not care for the look of quick jacks or bumpers! Like my car to look cleaner. Personal preference. I do now have killer looking grilles in ALL front openings though. Wherer are your grilles?
(lol)
Don

[donraye]

Originally Posted by nevermind65

Is this what you were looking at?

http://www.competitionengineering.co...?CatCode=10035

If so, you really wouldn't need this with the QA1 set-up. They literally bolt right in place. The only issue may be the lower mount is a little weak, but I believe you can buy a stronger one for only a few bucks.

Yes. But I just came from "TSR vintage and historics" at Infinion raceway. They do suspension work and track support for a bunch of Cobras over there. They think all I really need to do is change out the springs for longer ones in the correct weight and they suggest I put in Konis to replace the shocks on the car now. They think it will solve the problem and not cost as much as other methods. So I am not sure how Ill go at this point.

Well, I want to thank everyone for the great input and I have decided to go with the kit from Competition Engineering (url above) as they have the all the hardware included to convert and strengthen the top and bottom mounts. I also like that they will be spherical shock mounts and the kit was very well priced at Summit and seems easy enough to install(I hope!). I know it is a new kit so not many of you have used it but it has a good rep with a lot of users with Mustang tubs and Mustang street/strip cars so I'll try it out. Let you know later how it came out.
Thanks to all! Don

[donraye]

Quote from Clois:
"Also, you will probably want a spring rate of about 250#-300#. You can softern this up with the adjustable dampner that is available on some models of coil overs."

Clois
Clois, Are you saying a total rear spring weight of 250-300 lbs. or is that the rate for EACH spring?
I need to get this information correct.
Thanks, Don

[Clois Harlan]

Each spring! The spring rates are listed on each spring either in the top coil or somewhere on one of the middle coils. My Eibach's are engraved on the top and my Carrera's are stamped on one of the outside coils.

Clois

[ratsnst1]

HEY Don, just click on the camera, next to my name there and you will see my pics, Robert

[TButtrick]

I ran the stock FFR Pro Shock coil over upgrade for about 5 years with three link and was pretty happy. My tires are in pretty close quarters with respect to the body and had minimal rubbing on sharp dips. I bought a pair of Carrera coil overs from Vintage Performance last year and was amazed at the difference. They seem to have a more progressive dampening rate and have snubbers on the shock shaft you can add and delete as needed. Spring rate is perfect for road work on the FFR car and I'd imagine would be good on a similar weight car with similar weight distribution.

[donraye]

I did the coil-over conversion which took most of a full day last Friday as I had to remove the lower control arms and the 1" sway bar, wheels to have access to R&R the lower and upper mounts, etc. It was a pain in the Ass but I got it done with two floor jacks a pair of "Race Ramps" 4 jack stands.
Anyway.. I did end up using the 150 lb spring that came with the kit after talking to some other owner of this same car/set up and with the tech. rep at "Competition Engineering" the makers of this kit. I have a set of 275s that I was going to use but am now glad I did not.
I drove the car to show it in the "Hot August Niles" car show in Fremont this past Saturday and there were several different road conditions including some really bad road in a few places and lots of uneven roads and dips, etc. About 75 miles each way. The car handled very well on all of it. The ride quality was hugely improved, and there was no hint of any bottoming out at all. The car is like a completely new car now and it feels totally different than before and handles much better in all ways. So the opperation was a success and this post is just to thank everyone for your input and to let anyone interested know the outcome.
Warmest regards to all! Don

[TButtrick]

Glad to hear it all went well. Don't think of this as a $500 replacement for the faulty shocks. Think of it as a serious suspension upgrade opportunity that you got for way less than half the cost. Despite the current issues with the Bilsteins, this type of performance upgrade would normally cost you $1500 or more.

I have the ProShock coil overs with three link and Vintage Performance sway bar. Can you give us more detail on the needed mods? I thought it would be a pretty easy swap but wasn't thinking of any needed mods. I love the way the car handles now and could only imagine what the Konis would provide.