Polyurethane Rear Arm Bushings

[stockerbill]

I am replacing the bushings in the stock rear lower control arms with polyurethane. My OEM LCAs have round bushings at both ends. I see that both Energy Suspension and Prothane have a rear control arm bushing set that is specific for the SVO. I didn't think there was any difference between the regular GT LCAs and the SVO. Can anyone tell me the difference between the GT and SVO LCAs?

Thanks

[svono50]

The difference is in the front bushing, where the SVO actually used the 'older' style control arm with the round bushings and the 5.0L's had arms with an oval bushing to reduce NVH (see pic below). Unfortunately that large oval bushing allowed the rear axle to not only wallow around, but also wind up pretty good too. I am not completely sure when the oval bushing was introduced, but I believe it could have been as early as 82 with the return of the GT. I believe the 4 & 6-cyl versions may have retained the round bushing arms, but I am sure someone else can better nail down the details. I do know my 79 Turbo and 80 NA Mustangs both had round bushing lower control arms, just like my 86.

Control Arms - Rear_GT-LX-Cobra.jpg

[stockerbill]

Thanks Ted. My arms have round/round bushings and I had ordered a set of Prothane that came with the oval front, so that was obviously wrong. What confused me was when I went to reorder the set with the round/round set I discovered that there was also a set listed specifically for the SVO. The regular round/round kit is available off the shelf at Jegs and Summit, but the SVO specific is a special order. Since I didn't think there was anything special about the SVO, I wondered if I could just order the regular round/round set instead of waiting. I only need the lower arm bushings as my upper are being replaced with spherical bushings. Maybe I will just wait for the SVO kit to be sure. I started working on removing the original bushings yesterday and it is a major pain in the butt. I might take me a month to get the damn things out.

[FoxBuddy]

I did FCA's and upper RCA bushings last year on one car and FCA's on another fox this year. The ones in theses links are from my 82 GT and they were round/round. Here are some of my methods (under another username on FEP):

http://vb.foureyedpride.com/showthre...=1#post1572519
http://vb.foureyedpride.com/showthre...=1#post1573891

[svono50]

Not quite sure what the difference between the non-SVO and SVO specific kits are. A quick call to the tech line of the bushing company may help clarify the differences, if any. Getting the SVO kit is the safe way to play it in any case.

I used a slightly modified drill technique for removing the bushings, took about 5 minutes per bushing. I used either a 3/16" or 1/4" drill bit, ran it in between the bushing sleeve and bushing body just till the tip comes out the back side, held the drill from running the chuck into the bushing sleeve, let the drill bit walk itself around the perimeter of the bushing while still holding the chuck a small distance off the bushing, once the bit made one full track around the sleeve, the bushing should start to walk out of the sleeve, continue to let the bit walk around the sleeve keeping the chuck a constant distance off the bushing, after 5-10 rounds...pop comes the bushing. You will need to remove some material that remains bonded to the sleeve, but the comes out either with a torch or small wire wheel in a drill. Worked like a charm on all front and rear bushings for me, YMMV.

[stockerbill]

So I was able to get the bushings out of the rear LCAs without too much trouble. I have a press so I rigged up appropriate fixturing to put even pressure on one side of the bushing and a receptacle on the other side. I put about 1000 lbs of pressure on the bushing which compressed it some but didn't push it out. While holding the pressure I heated the shell with a heat gun and after a couple of minutes of heat there was a pop when the rubber bond to the shell let go. I could then just push the bushing out with the press. Pretty clean shell was left with just a bit of rubber still adhering to the metal which came out pretty easily with a cartridge roll on a die grinder. All ready for the new poly bushings which should be here tomorrow.

[JTurbo]

My experience is that you do not want to use poly bushings at all 8 points in the rear end suspension, it causes suspension bind and a harsh ride.

What I have done in the past is to leave 2 bushings in the upper arms (rear-end housing) with stock style rubber bushings....

Good luck!

[svono50]

I have to back Joe up with his warning, all 8 positions will virtually guarantee snap-oversteer in seemingly 'normal' conditions, which can cause some frightening situations on the street. I know, because I did this many moons ago in my former drag racing days. Worked great for getting me 1.7x 60ft times on the track, but ended up facing me backward staring at oncoming traffic a few times when a bump in the street was encountered while going around corners. Luckily I never hit a curb or any other vehicles when this happened, just embarrassed myself. Since I had already changed out my upper housing bushings I put in some stock bushing upper control arms prior to my first track day experience. Those stock arms helped add just enough compliance to the rear suspension to prevent snap-oversteer, while still being pretty stiff back there.

[stockerbill]

I am installing a Fays2 Watts link so I have spherical bearings/rod ends for the UCA. I am only using the poly on the lowers. I would have just bought aftermarket LCAs but SCCA Street Prepared class requires you to keep the OEM lower arms.

I received the bushing kit today but haven't been to the shop to do a test fit yet. I still cannot imagine how the SVO kit is different than the regular Fox that uses the round/round bushings. As long as they fit, I guess I'll never know. The kit has the UCA bushings but they are useless for my set-up.

[svono50]

I am installing a Fays2 Watts link so I have spherical bearings/rod ends for the UCA. I am only using the poly on the lowers. I would have just bought aftermarket LCAs but SCCA Street Prepared class requires you to keep the OEM lower arms.

I received the bushing kit today but haven't been to the shop to do a test fit yet. I still cannot imagine how the SVO kit is different than the regular Fox that uses the round/round bushings. As long as they fit, I guess I'll never know. The kit has the UCA bushings but they are useless for my set-up.

Hey, another SVO with a Fays2, cool! I switched over to the UMI uppers with roto-joints when I put in my Fays2, which has worked great for the past couple seasons. Enough hijack...back to our regularly scheduled thread...

[stockerbill]

Hey, another SVO with a Fays2, cool! I switched over to the UMI uppers with roto-joints when I put in my Fays2, which has worked great for the past couple seasons. Enough hijack...back to our regularly scheduled thread...

Well, I have spent two full days trying to install the Fays2 Watts link and I gotta say, what an unmitigated pain in the ass. If I had any idea of how difficult this would be I would have just done the Steeda 5 link setup. I still don't have it right and I just removed the prop and bars for at least the 10th time. There is absolutely NO room for error in the setup. There is nothing in the link structure that has any compliance whatsoever which would allow for even a tiny difference in either the bar length or the bar angles. If it isn't perfect, it will bind as the suspension moves. I can get what seems to be a correct setup at normal ride height, but as soon as the suspension travels a half inch or more the bars tighten up indicating that the link is binding somewhere. I am using a protractor app for my phone which is accurate to 1/2 of a degree and am matching the bar length the best I can using the method described in the instructions, but it just doesn't want to cooperate. I guess I'll keep dicking with it until I can get a useable setup, but I am really regretting my choice for rear suspension components.

[svono50]

You must have something crossed up on your setup, me thinks. Yes, all the adjustability of the Fays system does make it a bit of a challenge to get set up, but once you are even close it should move freely without any binding. Are the heim joints hitting the prop shaft? You are setting up the links and prop shaft to look like a "z", correct? The prop shaft should be at the 11 & 5 o'clock positions as viewed from the front of the car looking backward.

have the top link on the driver's side and it joins to the prop shaft over on the passenger side of the pivot bolt. The bottom link from the passenger side connects to the prop shaft on the driver's side of the pivot bolt...see pic below. I did have to make up my own spacers to get the links parallel to the axle tubes, as the ones provided were too short to get things into proper alignment. Jim Fay mentioned that he would ship me additional ones if I needed them, but luckily I have access to some machinist friends at work. I also figured out that the rod ends needed to be threaded in on the outer ends of the links and out on the inner ends toward the prop shaft to allow proper clearance between the jamb nut and the prop shaft.

The top pic shows the top of the prop shaft toward the passenger side and the bottom of the prop shaft toward the driver side. This picture also shows the rear axle at normal ride height, which is how I performed the install. Let me know if you have any other questions and I will try and work you through it.

Fays2 - Full Install_Driver_00.jpg Fays2 - Watts Bar_Passenger_Final_02.jpg

[stockerbill]

Thanks for your insight Ted. I took your advice here and also looked at your "17 years and counting" thread on that other forum and applied some of your experience to my situation. I was able to get the thing to work OK, not perfect, but functional with a couple of adjustments. The first thing was your method of biasing the link so that more of the propeller end heim thread is exposed to move the jamb nut away from the prop. Second was those miserable spacers. I needed two of the supplied spacers on the drivers side axle clamp which only left me with one for the passenger side. That was the primary issue on my set-up. In order to get the passenger side bar in anywhere near the correct position for angle and length, I needed more spacer on that side. I was able to find appropriate 3/4" spacers at a local supply house and using them on the passenger side I was able to get the bars equal length (almost) and equal angle (almost) at normal ride height. I think it is impossible to get exactly equal length since the passenger side heim has to be at an angle to its prop end while the driver side is at the same angle, but the difference isn't large. The angles are really close but not exact. It takes a lot of little adjustments on both ends to converge on an exact angle since changing the angle on one of the links changes the effective length of the link which in turn effects the other link angle. So it is little adjustments to hone in on the optimal. I do have it set up so that there is no binding in the linkage when going from normal ride height to maximum extension when the rear is hanging on a lift. The bars show no sign of binding now, but the angles of the two bars are different at full extension while they are the same at normal ride height. So there is still something that could be better but I don't know what. My suspicion is that in this situation the rear end is actually moving laterally slightly through the range of suspension travel, but it is probably a very small change, much less than a panhard rod in the same situation.

One thing that I did was to eliminate the rubber o-rings on the heim joints while doing the setup. The o-rings are OK for NHV but lousy for determining binding. Their effect masked how much slack there was on a bar in a particular position so leaving them out made it much more apparent when the whole linkage setup was not in a bind. I can always go back and add them one joint at a time if it is too noisy. The car will only be on a track so I don't think I will care. I think I am satisfied for now, and I can fine tune as I go. I just wanted to be absolutely sure that there was no binding going on before moving on to the next challenge.

BTW, Fays has changed the axle clamps for the 2.75" tubes so you don't need the shim material any more. I installed an 8.8 housing with 2.75" tubes and the clamps Fays supplied fit without any additional spacers. The passenger side is also much longer along the axle than the one you show in your "17 and counting thread", so improvements are being made.

[svono50]

Glad to hear one of my write ups had some useful info! Yes, I wholly agree that all that adjustability creates a real challenge for initial setup. It took me a good 5x, if not more to get things into alignment as moving one thing causes the other thing to be out of alignment and back and forth till you get it dialed in. It would be nice for Fays to include a couple more spacers so you don't have to hunt something down or have something made, like we had to both do. I felt comfortable getting things set up with the o-rings in place and figured I could always remove if needed, but I mainly drive my car on the street, so I was looking at them keeping some dust off the ball and extending the life of the rod ends. They should remain pretty silent till they get some wear and can move more easily, then they may move and make some sounds. There are plenty of other things making noise that would easily mask most end link noise anyway.

With the chassis suspension points as-is, having some lateral movement throughout the axle's movement isn't out of the question. Sure, you can get things centered at nominal ride height, but I certainly wouldn't want to bet a paycheck that it will remain perfectly vertical once moved up/down. The watts link will do its best to keep it in a virtual perfect vertical motion. The links won't remain parallel as the suspension moves up/down, you can see a good example at the bottom of this page: http://www.miracerros.com/mustang/t_suspension.html

As for the axle clamps, I thought they went from the wide to the narrow clamp on the passenger side?? My 8.8" rear is of the 2.75" tube diameter as well, but the clamps were for 3" tubes with the spacers. So far they haven't moved at all from my inspections over 2 years/4000 miles. I had to use clamp screws that were 1/2" longer, otherwise the thread didn't fully engage the nylon ring in the lock nuts...doh! I wish I would have had clamps that didn't require the shims, but so far they haven't caused any issues.

Post up some pics of your install if you get a chance, it would be interesting to see your setup.

[stockerbill]

Here are a few shots of my installation. I have UPR upper control arms and H&R race springs along with the urethane LCA bushings. I also have Koni Yellow DA shocks for the rear. The 8.8 has a Torsen diff and 3.73:1 gears.

IMG_20140731_160448_891.jpgIMG_20140731_160509_438.jpgIMG_20140731_160429_622.jpgIMG_20140728_125242_471.jpg

[MikeFleming]

All that red - brings a tear to my eye!

[svono50]

Nice looking setup! BTW, found a shot that I wanted to originally post with the position of the prop arm at normal ride height on my car...just took a while to find it. You can see the angle I chose for mine along with the rod end depth into the link arms. I also took a video of mine in motion during my initial road test, it is here on my Youtube channel if you are interested. About 1/2 way through the video I changed the location of my Gopro to get a different perspective of the suspension as I drove around. Not too much motion going on there, but you get the idea. http://youtu.be/2Z6Z8foncEg

Fays2_Prop.jpg