My 99 cobra hops VIOLENTLY even with IRS braces and bushings

SNAKEBIT7

New Member
Dec 31, 2009
13
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0
Newport, NC
Hi all,

I know there have probably been a million threads about wheel hop, but I feel like my case is unusual. I bought my 99 Cobra about 4 years ago bone stock. It did not hop at all!!!!!!!!!! I only had street tires then and I could roast the tires and it would not even attempt to hop. It didn't even hop when power shifting. It would spin, but not hop.

I then got the itch and modded the car with all of the following ALL at one time.

JLT CAI w/ K&N, UDPs, BBK Long Tubes, O/R X-pipe, T56, Mcloed clutch, aluminum driveshaft, 4.10 gears, IRS braces and bushings, Steeda sport springs, 18" chrome Saleen wheels w/ Nitto 555 DRs, custom predator tune.

Search for "Tim vs LS1 Camaro" on YouTube for my run. My run on YouTube was a fluke for me to be able to do a decent burnout. What you don't see on the video is that it initially was hopping horribly, then I brought the RPM down to below 2 grand and the hopping stopped, then I gradually added power. If I didn't have to limp out of the hole I could have probably ran close to a 13.0.

I doubt anyone has ever seen a Cobra hop this bad. My friends watching at the track said it was so violent that my body panels were flexing!!!Somewhere between the drag radials and sport springs and the poly bushings and the differential brace and another brace that the name escapes me right now.........something went horribly wrong. It even hops bad in the rain. If I get on it in the rain it will break traction and start to hop.

I just bought some Tokico D-Spec shocks and struts and the Steed IRS bracket, but haven't installed them yet. I hope that the problem is that I have the sport springs, but still only stock shocks and struts.

Please note that I only installed the poly bushings and braces as preventative maintenance when I did all my other mods. In hindsight I wish I left the IRS and springs alone since it did not hop. (If it ain't broke, don't fix it). I am shocked I haven't broken the half shafts.
 
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When you say IRS bushings, do you mean the front/rear IRS bushings or the differential bushings? The reason I ask, is that I had to drop my pumpkin this summer to fix a leak and replaced the IRS bushings with poly. The stock rubber IRS bushings are VERY soft and allow a lot of differential movement. After the poly install and the billet flow IRS brace, I have no clunk. I have not gotten on it enough to check for wheel hop. You might check out full tilt boogie racing's website - he sells an entire IRS kit that eliminates virtually all the IRS movement. Check him out....he comes highly recommended from satisfied customers.

Good luck....
 
I wonder if it is worse because we have convertibles? (weight, balance, etc.....)

Have you ever heard of anyone breaking (obliterating) their clutch disk splines? Check this out. This happened a couple days after my first trip to the local track after my mods. I was driving down the highway and it let go. I replaced this POS with a McLoed.

There are supposed to be mating splines!!!
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Made in China!!
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If you get an IRS you will have to replace bushings and stuff and possibly correct design flaws or incorrect parts from the line. With the IRS out of the car its straight forward and some can drop an IRS in less than 30 minutes. Steeda is good but MM is better and to save money there is a guy on SVTP named Bruce that makes a real nice complete kit for a bargain price.
 
The OP said his was fine stock, an hopped after the upgrades which is the opposite of what I've read happens. My goal is a fun driver, that gets some spirited street driving an sees the quarter mile 2 or 3 times a year. After buying the IRS, I plan on doing the mounting bushings for the sub frame an diff, an doing the upper an lower control arms later.
 
Need some info......... I'm too hard headed to give up on my irs, and I am considering upgrading to 31 spline half shafts and locker.

My questions are:

1) Is a 31 spline traction lock carrier out of an Explorer interchangable with an 03/04 Cobra carrier?
2) If so, will the Cobra shalf shafts work with it.
3) Since my car already has irs and all I'm looking to do is upgrade to 31 spline, is that all I need (the 31 spline half shafts and carrier?

Thanks for any info you can provide about this upgrade!
 
I have the poly bushings and the steeda diff brace already. I went for a drive today and I took off normally (ie didn't launch) and when I got into second gear I eased the clutch. Then after I was already into gear I got on it and it "broke loose and started hoping uncontrollable". I had to completely let out of it for it to stop hopping. If you were sitting in the back seat you would probably have your fillings loosened.

I wish I had never messed with the IRS now. The only reason I did was because I heard all the talk about how bad wheel hop was, and since I was having the Steeda sport springs put in, I had the guy put the poly bushings and diff brace in. I have the Steeda IRS subframe bracket kit (just haven't installed it). Before I have this thing welded in........has anyone heard anything bad about it?

I also have the Tokico D-Spec shocks and struts, and just haven't installed them yet. I just don't understand how the changes I've made have CAUSED IT TO HOP?

I looked into the kit that Bruce makes, and if the D-Specs and Steeda subframe bracket kit doesn't do the trick, then I'll probably get his bushing kit.

Anyone live in Eastern NC want to go for a ride to see the worst wheel hopping ever?
 
Do not make it hop you will shatter your diff cover or worse.

As soon as it start to hop YOU MUST GET OFF THE GAS. This is why no one drives my car but me because the first thing they are going to try to do is a burnout.
 
I know. I do let out asap. I didn't try to make it hop, I was trying to enjoy the drive.....LOL One reason I want to upgrade the half shafts is because I many have already done some damage or propagated a crack in the shaft or splines. Of course I should probably stick to the "if it ain't broke, don't fix it" philosophy.

Do you know anything about the weld in steeda subframe bracket kit? Good, bad?
 
Sorry I do not know anything about that bracket. I have heard the upgrading half shafts is a waste of money. It used to be very popular to do so but it looks like the OEM ones are as good as anything out there. And it is a very expensive upgrade that is fairly challenging to install.