Thoughts on replacing irs control arm bushings

[Storm728]

I have my irs out right now and totally apart while im waiting for parts to arrive. i replaced the stock diff mounts with poly ones and the old ones were totally worn out. i can also see wear and slight cracking on the control arm bushings. i have poly subframe bushings in the mail as well. ive heard the stuff about delrin being the go to material, however i do dd this car and i dont think i can put up with the harshness that some claim to have. but my real question is should i stick with the oem ~90k mile arm bushings and enjoy the other upgrades i did or spring for an upgrade to urethane and be done with it.

 

[03TopDown]

since you have the IRS out i would take advantage of it and replace every last piece of rubber in that thing. I would deff go with the Delrin control arm bushings and urethane diff/subframe bushings. i think it still rides pretty smooth with the upgrades. I would just do it right the 1st time.

since the pumpkin is out now would be a good time to do gears and differential if you want. But it is your DD so maybe you wanna leave that alone. Your call

make sure to throw a Diff cover brace or stronger cover on if you haven't already

 

[reldla1996]

I second to replace all the bushings now, and highly recommend the FTBR kit. The only bushings that really increase NVH are the front diff mounts, so leave those in poly (versus aluminum) if you're really worried about NVH. You'll lose some of the benefit, but still get a major improvement over the factory rubber bushings.

 

[shurur]

You will be sorry if you don't go delrin with solid diffy mounts and beefy toebars...I'm going to revisit my diffy mounts because I didn't have the solid mounts installed in the first place.

You can put some dynomat or fatmat around the diffy area of the trunk and behind the back seat to block the supposed noise.

FTBR is a better kit and most economical as well.

 

[Storm728]

kind of embarrassing to admit, but i cant really swing for the delrin kit at the moment. so im just wondering if i should go urethane or leave it alone

 

[SlowSVT]

kind of embarrassing to admit, but i cant really swing for the delrin kit at the moment. so im just wondering if i should go urethane or leave it alone

Borrow the money or rob a bank

Unless this is your DD and you need to get it back on the road this is the best time to upgrade the suspension. I would not do all that work reinstalling the suspension without it. The FTBR kit is probably the best handling mod you can do for the Cobra and it could save you from broken axles. Urethane is only good in this car for sway bar bushings and nothing else. I have the tools for removing the bushings and a 20 ton arbor press. You are more than welcome to bring your A-arms over and I will let you use my tools to remove and install the bushings while I watch you suffer :nonono: which will cost you a lunch or dinner as well :coolman:

 

[Storm728]

You will be sorry if you don't go delrin with solid diffy mounts and beefy toebars...I'm going to revisit my diffy mounts because I didn't have the solid mounts installed in the first place.

You can put some dynomat or fatmat around the diffy area of the trunk and behind the back seat to block the supposed noise.

FTBR is a better kit and most economical as well.

I second to replace all the bushings now, and highly recommend the FTBR kit. The only bushings that really increase NVH are the front diff mounts, so leave those in poly (versus aluminum) if you're really worried about NVH. You'll lose some of the benefit, but still get a major improvement over the factory rubber bushings.

since you have the IRS out i would take advantage of it and replace every last piece of rubber in that thing. I would deff go with the Delrin control arm bushings and urethane diff/subframe bushings. i think it still rides pretty smooth with the upgrades. I would just do it right the 1st time.

since the pumpkin is out now would be a good time to do gears and differential if you want. But it is your DD so maybe you wanna leave that alone. Your call

make sure to throw a Diff cover brace or stronger cover on if you haven't already

Borrow the money or rob a bank

Unless this is your DD and you need to get it back on the road this is the best time to upgrade the suspension. I would not do all that work reinstalling the suspension without it. The FTBR kit is probably the best handling mod you can do for the Cobra and it could save you from broken axles. Urethane is only good in this car for sway bar bushings and nothing else. I have the tools for removing the bushings and a 20 ton arbor press. You are more than welcome to bring your A-arms over and I will let you use my tools to remove and install the bushings while I watch you suffer :nonono: which will cost you a lunch or dinner as well :coolman:

might have to take you up on that brother

 

[Jefe]

Urethane is only good in this car for sway bar bushings and nothing else.

:bored:

OP, do the bushings while its out. You wont regret it. Heres some reading material for you: Taz's Chassis & Suspension

 

[Bingo13]

Another recommendation for the full FTBR kit. It is the best possible modification you can do for the IRS and in a lot of ways, for the car overall. If the kit is installed correctly you will not notice any additional NVH. Also, if you do any type of open tracking or auto-x, using poly in the front differential mounts will result in melting after a few events due to heat from the differential. Even as a daily driver, you will see deformation over time much in the same way as the original rubber wears out.

 

[SlowSVT]

:bored:

OP, do the bushings while its out. You wont regret it. Heres some reading material for you: Taz's Chassis & Suspension

Interesting article regarding the bushings but I have yet to hear of any delrin bushings failing out in the field (not saying they don't). Everyone who runs delrin bushings have been more than astatic regarding the handling improvements they make on the car and no excessive NVH. If I was designing a bearing Urethane would not even be considered as all it would do is distort on the crush sleeve under load and is not self lubricating (it galls). As far as problems with delrin being hydroscopic and swelling and seizing. I would see this as a possibility if the cars was driven continuously in a wet environment exposed to prolonged humidity. That broken A-arm looked fairly corroded in the first place which leads me to believe this was the case here. I think quite a few people who have lots of experience running delrin would disagree with that portion of the article which I thought was otherwise very good.

 

[Jefe]

I posted that just to show there are other options besides rubber and delrin. If we polled this entire section, it would be interesting to see how many are running delrin vs poly. Only a short time ago poly dominated the scene as it was the only aftermarket option. Delrin is a great mod but its not for everyone. There are definitely more guys with poly problems than delrin problems but mainly due to install failures like running lube between the bushings and cups rather than just the bushing and sleeve.

I have poly up front and it was a night and day difference compared to rubber. IRS is next, not sure which route im going yet with that

 

[Storm728]

i guess it all runs down to this because FOR ME money is an issue so im wondering if i should swing like 70$ and put in the urethane arm bushings or just leave it be and maybe get a diff brace, mind you i have urethane subframe bushings and diff bushings as well as mm full toe links. this will probably annoy some but its just the hand i was dealt right now otherwise i would strongly consider going for the delrin

 

[Midnight_Cobra]

Don't get poly please. I had MM's kit for about 30k miles before everything was crap and sloppy all over the place. I could remove them all by hand. Delrin is so much better. All this scientific crap, just stop please. If you install them correctly, and properly grease them at normal intervals. Nothing will happen.

I noticed no NVH when I installed my FTBR kit. But seriously, if you're concerned about a little rise in NVH...sell your car. It's a mustang, not an Audi.

 

[SlowSVT]

I posted that just to show there are other options besides rubber and delrin. If we polled this entire section, it would be interesting to see how many are running delrin vs poly. Only a short time ago poly dominated the scene as it was the only aftermarket option. Delrin is a great mod but its not for everyone. There are definitely more guys with poly problems than delrin problems but mainly due to install failures like running lube between the bushings and cups rather than just the bushing and sleeve.

I have poly up front and it was a night and day difference compared to rubber. IRS is next, not sure which route im going yet with that

I can definitely see how uethane will tighten-up the suspension over rubber but nothing like delrin will which is an ideal bearing material and it still has some shock absorption properties over a metal bushing. Uethane is "cold cast" and is very inexpensive to mfg. Delrin is expensive, has to be turned on a lathe which is likely why urethane was very popular and most likely the only available options for most cars over the OE replacement bushings. I've seen what happens to uethane bushings when they are used on an articulating joints if they get starved for lubrication and it ain't pretty :nonono: Delrin just wears out and will last a fairly long time running dry with no lubrication. The author on the Taz suspension article was not very subjective and overlooked a number of details not giving his readers the entire story.

 

[shurur]

i guess it all runs down to this because FOR ME money is an issue so im wondering if i should swing like 70$ and put in the urethane arm bushings or just leave it be and maybe get a diff brace, mind you i have urethane subframe bushings and diff bushings as well as mm full toe links. this will probably annoy some but its just the hand i was dealt right now otherwise i would strongly consider going for the delrin

Hey..I understand the money thing very well. I am an "old" down-sized, out-sourced, H1B'd design engineer. But that's enough politics for today.

You could replace the subframe and control arm bushings with FTBR UHMV/DELRIN products.
Then use the cheaper poly solution on the rest for now, phasing in the rest of the FTBR fixes over time.

This is pretty much why I still have the diffy mounts and toebars to do still.
The problem being you are replacing the least important fixes first.
It's Unfortunate that the least influentual parts on the IRS stability list are the hardest and most labor intensive to get to.

And so it goes.

BTW:
You may find a MM solid diffy mount kit in the market..I was going to sell mine for gas money to FL. but now i'll keep it.

And you can make your own DIY IRS toebars for about $160/pair.
?Swedge? tube and greasable heim joints..

And this is another option I am looking at once I get one out a measure it
Finding the right spindle bolt is the trick.
One poster on here got the spindle bolts from FTBR, but I'm not sure Bruce is going into the "IRS toebar spindle only business;" so we can all build our own. I certainly wouldn't.
then there is just drilling out the knuckle to 5/8" (like MM does for the front toelinks) and using a bolt..but the IRS knuckle may not be beefy enough for that.:shrug:

The road race guys have been doing this for some time...no DIYs theads yet....just little hints here and there.

Kelly is in FL waiting for me..with are car cover to protect her from the SUN!!!

 

[Blkkbgt]

Delrin bushings or keep it stock till you can get the cash together. I have ran both poly and Delrin at both ends of my car and I can tell you poly sucks. Initially it does make the car feel tighter but down the road the poly will start to squeak/creak especially in the morning when it is cold.

One thing most people don't bring up is the binding that is caused by poly bushings themselves. This happens because the hats of the bushings contact the ears of the mounts. When you torque the bolts down the binding is then created. This contact between the bushing hat(s) and mounting points also increases the squeaks and creaks later on down the road.

Now some will argue that Delrin will increase NVH. This all depends on where it is installed. In control arms you wont notice it. As soon as you install them you will notice how the arms are free to articulate with nearly zero bind. I attribute the near zero bind with smoothing out the ride in my car because before the FTBR kit the rear end felt spongy and seemed to dance a lot over un even pavement.

So again get some delrin bushings or leave it stock. No sense in doing the job twice.

 

[shurur]

Delrin bushings or keep it stock till you can get the cash together. I have ran both poly and Delrin at both ends of my car and I can tell you poly sucks. Initially it does make the car feel tighter but down the road the poly will start to squeak/creak especially in the morning when it is cold.

One thing most people don't bring up is the binding that is caused by poly bushings themselves. This happens because the hats of the bushings contact the ears of the mounts. When you torque the bolts down the binding is then created. This contact between the bushing hat(s) and mounting points also increases the squeaks and creaks later on down the road.

Now some will argue that Delrin will increase NVH. This all depends on where it is installed. In control arms you wont notice it. As soon as you install them you will notice how the arms are free to articulate with nearly zero bind. I attribute the near zero bind with smoothing out the ride in my car because before the FTBR kit the rear end felt spongy and seemed to dance a lot over un even pavement.

So again get some delrin bushings or leave it stock. No sense in doing the job twice.

+1
I noticed it when I did the front arm bushing (rubber) and the folks who installed the bushings on the IRS mentioned it right away. they were able to work with it because of the rubber bushing bind, then after putting in the delrin, they needed an extra jack(s) to put the irs back in place.

Poly is too much like rubber.

 

[Storm728]

Delrin bushings or keep it stock till you can get the cash together. I have ran both poly and Delrin at both ends of my car and I can tell you poly sucks. Initially it does make the car feel tighter but down the road the poly will start to squeak/creak especially in the morning when it is cold.

One thing most people don't bring up is the binding that is caused by poly bushings themselves. This happens because the hats of the bushings contact the ears of the mounts. When you torque the bolts down the binding is then created. This contact between the bushing hat(s) and mounting points also increases the squeaks and creaks later on down the road.

Now some will argue that Delrin will increase NVH. This all depends on where it is installed. In control arms you wont notice it. As soon as you install them you will notice how the arms are free to articulate with nearly zero bind. I attribute the near zero bind with smoothing out the ride in my car because before the FTBR kit the rear end felt spongy and seemed to dance a lot over un even pavement.

So again get some delrin bushings or leave it stock. No sense in doing the job twice.

will do, but to clarify the poly should be fine in the subframe mounts because they dont articulate

 

[Blkkbgt]

will do, but to clarify the poly should be fine in the subframe mounts because they dont articulate

Yes it will be fine in that location. I would keep an eye on them though. I have seen poly bushings (prothane) distort after about a year.