strenthing my IRS

1350 Views 27 Replies 11 Participants Last post by M.P. Cobra Fan, Nov 20, 2009

CobraVert69

Discussion Starter · Nov 16, 2009 (Edited)

Strengthening my IRS

so i have a 99 cobra and its got pretty much every bolt on possible except pullies for now. im about to put a 4.10 in it to liven it up a bit but i dont want to blow my irs setup. i was thinking bullitflow irs brace and front and rear bushings but i thought id take a few opinions from the pros. my questions are 1. are pulleys even worth getting? and 2. how much of a difference should i be seeing going from a 3.27 rear end to a 4.10. thanks guys!! btw heres a vid of it with the slp loudmouth 1's before i switched them out with magnaflows for the people who are wondering what loudmouths sound like. my hair is also alot shorter now hahaha

1 - 20 of 28 Posts

Lefty

· #2 · Nov 16, 2009

You'll see a HUGE difference w/ the 4:10's in there.

M.P. Cobra Fan

· #3 · Nov 16, 2009

4.10's were a night and day difference in my car. When I did the gears I also added the MM IRS diff bushings, Steeda IRS brace, and MM FLSFC. Wheel hop has been reduced, but is still present on some launches. The harder I get on it on the launch, the less hop, but the more spin. I have to be very careful in the rain now because if I am rolling and do not accelerate smooth in 1-3 the wheels spin and the car slides sideways.

As for the pulleys, if they are worth it is all a matter of opinion. Alone, no bolt on is really worth it. Once you start adding them all together though the story is different.

wraitherx

· #4 · Nov 16, 2009

+1 on what that **** said

CobraVert69

Discussion Starter · #5 · Nov 16, 2009

thanks guys!!! any other suggestions?

rk_2000_Z/28

· #6 · Nov 17, 2009

Replaci g the weak bushings is a great start. Check out full tilt boogie racing.

CobraVert69

Discussion Starter · #7 · Nov 17, 2009

yeah thats what i figured. we'll see what i do with it. im pretty new to this forum thought id introduce myself really quick. i'm currently 17 but i'm starting a life early in automotive. this is the car that ive put about 99% of my life savings in and everything and i also own the Taurus Rage concept car. and i have a little civic with 18's and coilovers for a DD/ kid insurance for people who like to **** with cars at my age haha. heres a link the the taurus i own. its 1 of one ever made. The pics were taken at SEMA and behind the SEMA building. thanks for all the help so far guys btw i really appreciate it!!!

1999 Taurus Rage Concept | Taurus/Sable Encyclopedia

Mr.Soup

· #8 · Nov 17, 2009

CobraVert69 said:
thanks guys!!! any other suggestions?

Go to Full Tilt Boogie Racing Homepage and check out their rear bushing set for the IRS. that along with the irs brace and a set of 03-04 half-shafts and you'll be set. the bushing set is'nt cheap and if I'm not mistaken you'll have to upgrade the spiders in your pumpkin to 31 splines since your 99 has 28. however if you do the bushing kit alone you'll be out handling vettes and vipers. I would highly recommend the gear swap but in my opinion if your going 4:10s might as well go 4:30s. it's only a few hundred difference in RPMs. A lot of the people I know went with 4:10s and wish they'd gone 4:30s afterwards, our cars are heavy and the cubic inches are small so the more gear you throw at the car the better they respond. these

I have a full 04 IRS sitting in my garage and am getting ready to order the bushing kit myself, that with a set of 4:30s i already have and the Eibach sportline springs in my car now will make for a completely different car. the bushing kit is really involved and will take a couple days to do even if you're familiar with the set up thats why I sourced a seperate IRS and am doing it over the winter, that way come spring its drop the old one and install the upgraded one (sell old one to re-coop cost) im also upgrading shocks at the same time but am still up in the air as to which ones to get.

hope this helps, but again this is just one mans opinion.

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M.P. Cobra Fan

· #9 · Nov 17, 2009

Read This
The Mystery of the Cobra Independent Rear Suspension - SVTPerformance

Mr.Soup

· #10 · Nov 17, 2009

M.P. Cobra Fan said:
Read This
The Mystery of the Cobra Independent Rear Suspension - SVTPerformance

i was gonna post that link i just figured the full tilt boogie racing one would stter him in the right direction too. that Bruce guy makes some seriously good bushings not to mention hes about as knowledgable as they come when it comes to mustang suspension

98Cobra_sleeper

· #11 · Nov 17, 2009

that taurus is badass

Diabeetus

· #12 · Nov 17, 2009

With just bushings your car will NOT out handle vettes and vipers. It will reduce hop and handle a little better. If you go to 03-04 half shafts you will have to get a new carrier because yours is a 28 spline. Spider gears have nothing to do with it so I dont know what Mr Soup was talking about. I have 4.10s in my '01 and love them. My freeway RPM went from 2150 at 80mph to about 2650 at 80 mph. The gears really wake the car up. I feel the 4.10s are great, but I might have gone with 4.30s had the others not been free.

Get the IRS diff cover brace for sure, and at least replace the subframe bushings with polys.

Safi

· #13 · Nov 17, 2009

Not sure if it's been mentioned....but you'll also want a HD crossmember to go along with that IRS brace

CobraVert69

Discussion Starter · #14 · Nov 18, 2009

thanks for the comment on the taurus!. its a pretty cool car! and we'll see what i do with mustang. i would just rather put 1000 dollars into strenthinging the susupension then 1500 fixing it haha

CobraVert69

Discussion Starter · #15 · Nov 18, 2009

just a quick Q. Should i go with the big kit from The boogie racing company or Maximum Motorsports? i kinda like the MM products. ive heard alot of good things about them but you guys are the experts. whats your input on the 2 different companies

M.P. Cobra Fan

· #16 · Nov 18, 2009

Both companies are excellent. Both offer an excellent product. It all depends on how hard you are going to be driving the car. I have started replacing the bushings in my car and choose to go with MM. I chose them for 2 reasons. 1, my car is a mall cruiser, not track car. 2, price. Delrin bushings just seemed a little rough for what I was doing. I stil want to keep the ride smooth. However, I have since talked to people with the FTB delrin ki, and they have assured me their ride is smooth. I have thought about finishing the car up with the delrin on those harder to replace bushings.

Mr.Soup

· #17 · Nov 18, 2009

Diabeetus said:
With just bushings your car will NOT out handle vettes and vipers. It will reduce hop and handle a little better. If you go to 03-04 half shafts you will have to get a new carrier because yours is a 28 spline. Spider gears have nothing to do with it so I dont know what Mr Soup was talking about. I have 4.10s in my '01 and love them. My freeway RPM went from 2150 at 80mph to about 2650 at 80 mph. The gears really wake the car up. I feel the 4.10s are great, but I might have gone with 4.30s had the others not been free.

Get the IRS diff cover brace for sure, and at least replace the subframe bushings with polys.

i thought the spider gears inside the carrier are what the axles insert into? if thats the case in order to upgrade to 31 from 28 all youd need is the spider gears right? the vipers and vettes comment was taken from the svtperformance website. in it Bruce (who makes the bushings) talks about how sloppy the factory bushings are while road racing, after making and installing his bushing kit he said he was out handling vipers and vettes. all the guys over on the svt performance board swear by the delrin\aluminum combination in the fulltiltboogieracing set compared to the MM ones. several guys on that site have talked about the MM ones deteriorating after just a couple years.

M.P. Cobra Fan

· #18 · Nov 18, 2009

The FTB kit is HUGE on SVTP. MM is very much a serious player in road racing as well. I don't know anyone personally who has had the MM ones wear out, but it is poly so who knows. I would never bash FTB, nor am I am MM nutswinger. If I bought something that I regret I would say so. I do not regret the MM purchase as of yet. Although, like I said, I will probably be going over to the FTB delrin kit once I can down the car for a while.

Mr.Soup

· #19 · Nov 18, 2009

M.P. Cobra Fan said:
The FTB kit is HUGE on SVTP. MM is very much a serious player in road racing as well. I don't know anyone personally who has had the MM ones wear out, but it is poly so who knows. I would never bash FTB, nor am I am MM nutswinger. If I bought something that I regret I would say so. I do not regret the MM purchase as of yet. Although, like I said, I will probably be going over to the FTB delrin kit once I can down the car for a while.

the only negative i have heard about the FTB kit is the aluminum diff bushings transfer a lot of road noise into the cabin. i have been told its pretty signifigant but considering i have the LM1 catback and soon an off road X i doubt ill be able to hear much over that

CobraVert69

Discussion Starter · #20 · Nov 19, 2009

i did some research on the cost of having bushings installed and its about 800 dollars so i was wondering if its a bad idea to put the 4.10 gears in w/o a bushing kit and maybe just with an irs brace. atleast for a little while. i dont really launch the car so im not sure what i can do. i really want to get some AFS wheels for it but i dont think ill be able too with the bushing kit. whats your input on it guys?

thanks!

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