Rear upper control arm bushings on differential.

Topic: Rear upper control arm bushings on differential. (Read 2676 times) previous topic - next topic

Rear upper control arm bushings on differential.

Reply #15 – September 17, 2012, 02:59:45 PM

Chuck every one of my cars have poli in all the positions. Absolutely no issues. Just saying. The air chissel can be used with a Snap On adapter. But i have seen people over do it and snap off the ears. I am not kidding. I always use a support sleeve when doing the rear bushings that press in to the upper ears. Just me. I am over cautious on things like this. The service manual does show a ford tool with a plate driver for this purpose. But doing it in the car. NO ROOM to use the tool. Thanks

Rear upper control arm bushings on differential.

Reply #16 – September 17, 2012, 03:25:59 PM

You can run poly at all the RCA locations in your cars if you like, I will not. The splayed 4-link WILL bind with poly.

Rear upper control arm bushings on differential.

Reply #17 – September 17, 2012, 05:06:56 PM

Chuck i respect you knowledge on this issue and i am very interested in this issue you bring up. Can you elaborate as i for one have dun many of these for customers. Not only on Fords but on several GM cars as well. Any info you can pass on will be appreciated. I know you are a sereyous guy when it comes to suspension. The 4 link setup on these cars are not designed to be put in a bind situation by design. And most aftermarket bushings are now made from poly. basically the 4 link is in my mind a non binding configuration by design. In the shop we have ran the suspension up and down to check for this. We see no issues. But i am very interested in your info. As we run the 1320 with poly the car normally hook up better and with less wheel hop. Years ago i used to drive finish nails in to the rubber around the permimiter of the joint. This stiffened up the suspension quite a bit. With the introduction of poly it changed the playing field. So with that please explain as i am very concerned with this. Thanks!!

Rear upper control arm bushings on differential.

Reply #18 – September 17, 2012, 05:15:48 PM

I went back and I am in the process of re-reading "Polyurethane on control arms". I got a lot of good solid information on that thread. I also notice that Thunderbirdsport302 mentioned that he put aluminum upper axle bushing on his to prevent binding. Thunderbirdsport302, if you see this, please give us more details on you set up. Aluminum I would think would be even less deflection and more likely to bind (??).

Rear upper control arm bushings on differential.

Reply #19 – September 17, 2012, 05:26:45 PM

Oh, I forgot... I just finished taking all the bushings out of my rear control arms like Tom suggested. Pretty cool! There is a small learning curve (my first one), but then I remember what you said about it "pops". Mine were more like a "sizzle" and sometimes they would act like those old fireworks I used as a kid "snakes". They would ooz out and catch fire. I just treated like a steak, cook it evenly, make it sizzle. Then it would just slide out like you said. That old petrified rubber sure smells awful funky!

Rear upper control arm bushings on differential.

Reply #20 – September 17, 2012, 09:54:08 PM

86 been doing it that way for many many years. Glad i could help. Like i said sometimes they pop had to throw that in for safety. Glad i could help. I am still up in the air about the binding thing. But i do respect Chucks experience. He is very knowledgeable on these things. I am going to contact the DOG tomorrow he builds custom frames and does a lot of birds. he is a custom chassis builder. I hope Chuck chimes in as i respect his thoughts and experience.

Rear upper control arm bushings on differential.

Reply #21 – September 17, 2012, 11:48:31 PM

Quote from: TOM Renzo;398431

Chuck i respect you knowledge on this issue and i am very interested in this issue you bring up. Can you elaborate as i for one have dun many of these for customers. Not only on Fords but on several GM cars as well. Any info you can pass on will be appreciated. I know you are a sereyous guy when it comes to suspension. The 4 link setup on these cars are not designed to be put in a bind situation by design. And most aftermarket bushings are now made from poly. basically the 4 link is in my mind a non binding configuration by design. In the shop we have ran the suspension up and down to check for this. We see no issues. But i am very interested in your info. As we run the 1320 with poly the car normally hook up better and with less wheel hop. Years ago i used to drive finish nails in to the rubber around the permimiter of the joint. This stiffened up the suspension quite a bit. With the introduction of poly it changed the playing field. So with that please explain as i am very concerned with this. Thanks!!

The splayed 4-link in the Foxes most definitely WILL bind. The reason it doesn't in stock form are the very soft rubber bushings Ford used to allow things to twist as the axle articulates on bump and in roll. Spherical bearings at all locations would be better for articulation, but lousy for NVH. Big rubber bushings cause wheel hop on launch, so Ford's band aid was to install the Quad-shocks. These helped dampen the oscillations, but were just that, a band aid. Poly bushings help eliminate the wheel hop issue, but are lousy for the articulation needed as the rear axle goes through its motions of bump and roll.

You need some point of give in the system, otherwise what happens is when the bushing resists the twisting force, it causes the "effective" spring rate at the wheel to increase. The worst instance is when there is no more give, and things bind (the effective spring rate goes through the roof). While it's not usually an issue tooling around on the street, and the car usually "feels" better, that "one" time you are giving it hell at the limit in a corner, and the suspension binds, you are headed off the road. "Snap over-steer" is the term you're looking for.

Rear upper control arm bushings on differential.

Reply #22 – September 18, 2012, 01:04:26 AM

Cool! Thanks, for taking the time to explain that Chuck! I figure that the one time I give it hell around a corner is the worst time for the sh_t to hit the fan! Snap over-steer sounds like a nice way of saying by-by 86Cougar. Here is my dilemma, I have a kit of poly's, and I have two worn out bushings on my differential. Where could I buy just the two rubber bushings that I need? Would I be safer just using the two old bushings and the rest of the kit? Tom has helped me a lot since I've come on board, and it sure sound's like he has a lot of respect for you, so if you don't mind, I'd also like to hear more for safety's sake. Thanks!

Rear upper control arm bushings on differential.

Reply #23 – September 18, 2012, 05:42:41 AM

I am lost for words on Chucks answer. As most of the CHASSIS builders in the area confirm that the bushings should be changed out to POLY. Fact is FORD actually changed the arms from OVAL at 2 points to a set of ALL ROUND units on the lowers. They also installed the QUAD SHOCKS to eliminate chassis wheel hop and movement. According to My buddy over at the chassis shop the poly bushings wont bind the BIRD. They are not solid and wont increase spring rate. As posted the inside sleeves on the bushings in fact are not permanently fused to the bushings in the ones we use. Their fore the bushings we use wont bind. With that i am all confused on this subject and i do respect CHUCKS answer. But this opens a whole new can of WORMS. Or should i say POLY???

Rear upper control arm bushings on differential.

Reply #24 – September 18, 2012, 08:57:04 AM

Quote from: TOM Renzo;398504

I am lost for words on Chucks answer. As most of the CHASSIS builders in the area confirm that the bushings should be changed out to POLY. Fact is FORD actually changed the arms from OVAL at 2 points to a set of ALL ROUND units on the lowers. They also installed the QUAD SHOCKS to eliminate chassis wheel hop and movement. According to My buddy over at the chassis shop the poly bushings wont bind the BIRD. They are not solid and wont increase spring rate. As posted the inside sleeves on the bushings in fact are not permanently fused to the bushings in the ones we use. Their fore the bushings we use wont bind. With that i am all confused on this subject and i do respect CHUCKS answer. But this opens a whole new can of WORMS. Or should i say POLY???

First, Ford used the all round bushings in the early cars. They changed in '83 to the big oval ones in front of the RLCA to cut down on harshness. The only Fox to use them after that was the SVO, which was marketed as a "driver's car", and not just a neo-musclecar. After they changed to the oval bushings they realized they had an issue and instead of keeping the slap bars the early cars had, they went to the quads to help dampen the diff bouncing up and down on hard launches due to the big rubber bushings.

Second, you and your chassis guy are missing the point. Yes, the internal sleeves are not bonded to the bushings like the rubber ones are, so yes, when the control arm moves in an arc around that pivot there is no binding. However, when the body rolls, the rear axle is not moving in that nice up and down arc, it is actually causing those sleeves to twist in the bushing as the mounting points on the axle are now no longer being asked to move at parallel axes. The motion is actually trying to twist the control arm. The stock rubber allows for that bit of twist, and poly doesn't. When it can't twist, it binds.

Now, using poly in stock un-boxed stock control arms MAY be OK, seeing as how flimsy the stock arms are, but if you have aftermarket or boxed stock arms loaded with poly, not much twist is going to happen there, and there for certain WILL be spring rate increase and bind. I'd rather be twisting rubber bushings than my control arms, though. The stock splayed 4-link in the Foxes is asked to do a lot of things, and is not very good at any of them once you start pushing it.

Quote from: 86cougar;398501

Where could I buy just the two rubber bushings that I need?

You should be able to get those at the dealer. They were used on Mustangs until '04, so they shouldn't be obsolete...yet.

Rear upper control arm bushings on differential.

Reply #25 – September 18, 2012, 10:23:23 AM

I'm glad I read this...just ordered factory style rubber upper bushings. I had no idea it was a bad idea to run all poly bushings!

Rear upper control arm bushings on differential.

Reply #26 – September 21, 2012, 10:13:05 PM

http://www.maximummotorsports.com/store/index.php?main_page=index&cPath=21_98

Be sure to click on the "Rear Lower Control Arm tech section" link in the third paragraph and read up on that page as well. Pretty much tells it like it is or should I say Chuck said. This is common knowledge in the Fox Mustang world if you do any kind of racing that involves turns.

Darren

Rear upper control arm bushings on differential.

Reply #27 – September 21, 2012, 11:10:21 PM

The whole rear end is done. I ended up using stock bushing for the differential and poly every where else. The differential has fresh oil, the rear end has new shocks, springs, anti-sway bar and brakes. I want to thank all of you for you opinions, knowledge, and help. Nice attachment Aerocoupe!