updated
The IRS Tech Article
- Thread starter Snake Eyes
- Start date
Updated once again. I want to know if anyone wants any changes made, eg clarification, specific questions, a total rewrite... etc. I am considering changing the articles format and potentially making it the Suspension FAQ (covering front and rear).
All comments are welcome.
All comments are welcome.
Snake Eyes said:
Kyle:
I can see that you have gone to considerable lengths to compile that great list of information regarding the IRS. It's good stuff.
Although I'm not here to say bad things about MM's stuff (heck, I love their stuff!) but I am not a big fan of poly bushings. Are they better than rubber? You bet! Is there a better material to use in it's place? You bet! The Delrin compoments they sell are some very spendy items. If you don't care about price, then their stuff is for you!
IMHO simply removing all of the rubber in the IRS is the biggest improvement you can make as far as stabilizing the IRS is concerned. It does come at a price of increased NVH however.
Many SVTP members have found a cost effective alternative the the spendy MM components in the complete Aluminum, Delrin and UHMW IRS bushing sets Ken and I are offering. You can find the main thread here:
http://www.svtperformance.com/forums/showthread.php?t=160766
Sorry, it's kind of long. There is a shorter, more consice version of same located in the Market section here:
http://www.svtperformance.com/forums/showthread.php?t=260665
There is a good possibility I will also be offering this Delrin Control Arm set for the Kenny Brown converted IRS in the not too distant future.
Stay tuned!
:thumbsup: :coolman: :beer:
Actually Bruce if you look I do recommend your kit (it is in the control arms and differential mount bushings section). And the only place I recommend polly is for the subframe and the swaybar. The sway bar because there is no other material offered by anyone for that application, and the subframe because most cobras are street driven so it is a good way to cut down some road the noise. I haven't had experience with UHMW subframe bushings and do no know how much benefit they would be over MM's polly subframe bushings so I can not speak to that end but I would never recommend polly for the control arms or any other moving piece as it quite simply is not the correct material for the job. But in the last section I do recommend going to aluminum subframe bushings rather than polly for track cars. Give her a re-read and let me know what you think.
Snake Eyes said:
Hee Hee, guess I need to read more thoroughly?!?!
I was sort of focused on the Poly cradle mounts portion of the post I guess?!? Sorry! The sub frame really needs the UHMW pieces. Poly is ok, but it will not hold the assembly as tight as the UHMW will. Removing anything that gives is important as you well know.
IMHO the biggest offender in the NVH department is the aluminum front diff mounts. But hey, what do you want, function or quiet ride? Want a quiet ride, get a Lincoln! :coolman:
Good stuff you have going there!!
:thumbsup: :coolman: :beer:
Well like I said I have no experiance with the UHMW pieces. If you wanna cut me a deal on a set I will swap mine out. :-D
Cobra Kai said:
It is important to some of us, but happy to provide quality info.
Added this section just to prove to all the solid axle guys that the IRS is better at everything except drag racing.
=========== MM on the Mustang IRS ==========
NASA Pro Racing – Interview with Chuck Schwynoch, CEO
Maximum Motorsports, Inc.
June 28, 2006
By Andy Bowman
Q. The #91 MM Mustang is using an IRS rear suspension, what drove you to this decision, how has the effort been going so far?
A. We had a growing number of customers who called us and said that they were not happy with their IRS, and asked us if they should swap in the proven MM Torque-arm/Panhard Bar rear suspension. We couldn't give them a truthful answer until we had done our own testing to directly compare the Ford IRS to a well-sorted Torque-arm/Panhard bar system. Our AI race car had won races, and set track records, so it was the perfect candidate for comparison. We swapped the rear end over to the IRS, with all of the parts we had developed over the previous year on a street-driven 2003 Cobra. We left the front of the car exactly as it was with the Torque arm suspension. We maintained the exact same rear track width, and even swapped over the same brakes, rotors, calipers, and pads, from the solid axle. We then hit the track for testing. By the end of the first day of testing we were 3 seconds under the AI track record at Buttonwillow. With the IRS we had to learn what alignment and bumpsteer settings worked best. That's what testing told us. Without track testing, we really could not have given our customers an honest answer to their questions about the IRS. Even if our testing had shown the IRS to be grossly inferior to a solid axle, we at least would then be able to help our customers make an informed decision about modifying their car. As it turned out, the IRS is superior to a solid axle fitted with a Torque-arm and Panhard bar, in most aspects.
=========== MM on the Mustang IRS ==========
NASA Pro Racing – Interview with Chuck Schwynoch, CEO
Maximum Motorsports, Inc.
June 28, 2006
By Andy Bowman
Q. The #91 MM Mustang is using an IRS rear suspension, what drove you to this decision, how has the effort been going so far?
A. We had a growing number of customers who called us and said that they were not happy with their IRS, and asked us if they should swap in the proven MM Torque-arm/Panhard Bar rear suspension. We couldn't give them a truthful answer until we had done our own testing to directly compare the Ford IRS to a well-sorted Torque-arm/Panhard bar system. Our AI race car had won races, and set track records, so it was the perfect candidate for comparison. We swapped the rear end over to the IRS, with all of the parts we had developed over the previous year on a street-driven 2003 Cobra. We left the front of the car exactly as it was with the Torque arm suspension. We maintained the exact same rear track width, and even swapped over the same brakes, rotors, calipers, and pads, from the solid axle. We then hit the track for testing. By the end of the first day of testing we were 3 seconds under the AI track record at Buttonwillow. With the IRS we had to learn what alignment and bumpsteer settings worked best. That's what testing told us. Without track testing, we really could not have given our customers an honest answer to their questions about the IRS. Even if our testing had shown the IRS to be grossly inferior to a solid axle, we at least would then be able to help our customers make an informed decision about modifying their car. As it turned out, the IRS is superior to a solid axle fitted with a Torque-arm and Panhard bar, in most aspects.
What is this proving other than it's a scripted advertisement for MM?
It proves that the IRS is faster around the track. There has long been a debate going on as to the feasibility of the IRS as a performance suspension. Everyone already knows it rides better but I just get sick of all the solid axle guys telling everyone that a solid is a better over all solution and that you cant get rid of the hop, it doesn't handle bla bla bla. I know you can get rid of the hop, completely and now we know it can be configured to go faster around the track so unless you are building a drag car or are just stubborn the IRS is the way to go. And as far as suspension shops who's parts and opinions I trust completely, Griggs and Maximum Motorsports, period that is the list. There are other shops that produce good parts and what not but Griggs and MM are head and shoulders above the rest.
b_tone said:
IMHO the statement is supposed to inform the IRS haters that the IRS is not as bad a SOME people think it is? Even in the compromised condition it comes in delivered from the factory. :shrug: :read:
Snake Eyes said:
Exactly what parts do Griggs and MM produce that make the IRS work so well? The second part of that question is how do those parts improve it so much that the performance the stock IRS module can jump past a well setup solid axle?
Just the data would be fine. Thanks.
Read the first post in this thread it will answer most questions you will have about the IRS. It systematically addresses all the shortcomings of the IRS and tells you what can be done to address them. It includes all the parts from every manufacturer that are required including Griggs and MM. Now Griggs believes in the solid where as MM likes both but both companies make great parts and give sound advise. Now as for hard data I don't have it, MM has done the testing in their race car. If they feel it is more competitive and faster then I believe them. If you want me to I can call or email MM and get lap times but I think the direct quote speaks for it self.
b_tone said:
I completely disagree with your interpretation. It represents MM giving a fair view of the IRS. Just like what has been said above, the IRS is superior to a live axle in the daily drive arena but no one had given it a fair rub as far as track testing with a proper set up. MM used their off the shelf stuff and proceeded to LEARN the IRS and lo and behold, it was faster.
The biggest difference between the cost of properly setting up a live axle and the IRS has been reduced to time. It costs about the same to do both with Bruce's kit being just $550. Effort is all that seperates the two.
I am in the middle of the whole conversion right now and let me tell you, it is a TON of work but in the end, I will have a car that is faster than a solid axle equivalent and enjoy the pleasant road manners the IRS has come to be praised for.
Reading all of this help me a lil bit as well as confused the crap out of me. I have a 2001 Cobra w/ all stock suspension parts.
There are only a couple things that I want out of the suspension...
1. Lower the car and improve the handling a lil bit when playing on twisty roads.
2. Picture yourself in your Cobra racing up to a 100+mph. You shift from 3rd to 4th and plant your foot back into the throttle. Now after the fast shift, picture the rear of your car rocking left to right as well as bouncing up and down. It's pretty much a loss of control feeling put the tires are still planted solid on the ground.
I want to cure that feeling I just described.
What are the basics that I would need to complete these two goals?
There are only a couple things that I want out of the suspension...
1. Lower the car and improve the handling a lil bit when playing on twisty roads.
2. Picture yourself in your Cobra racing up to a 100+mph. You shift from 3rd to 4th and plant your foot back into the throttle. Now after the fast shift, picture the rear of your car rocking left to right as well as bouncing up and down. It's pretty much a loss of control feeling put the tires are still planted solid on the ground.
I want to cure that feeling I just described.
What are the basics that I would need to complete these two goals?
check your rear wheel bearings and the tightness of the axle nuts. you are describing worn wheel bearings but the axle nut is how the rear bearings are preloaded.
Your toe rods could also be at fault. Check them to make sure they are torqued and in proper alignment.
DC97Cobra said:
Jack up your car and feel both rear tires for play in both up and down and side to side motion. If you don't have any play you're just a victim of rubber. Rubber allows too much movement in all of your suspension components and causes your car to get squirrelly when some pressure is applied to it? Simple as that.
:thumbsup: :coolman: :beer:
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