[dzenno]

I was going to post this in the suspension category but felt it'd get a lot more attention in this section of the board...

A bit of history: Recently had a Wavetrac LSD put in as well as a 6 puck ceramic clutch and lightweight flywheel. These components put additional stress on the rest of the driveline components that haven't been upgraded to stronger components such as rear half shafts (rear drive axles), gearbox, wheel bearings, rear subframe, etc. As some of you already know this past weekend I managed to snap one of my rear half shafts (driver's side one). When I took them off the car I noticed that even the passenger side one was damaged for who knows how long and didn't have smooth movement at the CV joint, it was binding quite a bit.

Car's at the shop right now and half shafts have been sent down for a 1000hp upgrade using chromoly bars by the Driveshaft Shop and they should arrive back next week (4-5 day turnaround once they get them, thanks Former_Boosted_IS for your review, just in time). This is a great upgrade and alternative to purchasing a new OEM set of halfshafts that carry the same risk of breakage as the previous set and I can't wait to get them installed. On top of that I've ordered a few M3 rear suspension bits to firm up rear suspension and plant it better on the ground (M3 rear subframe mounts and an M3 rear wishbone kit) from Tischer...

Currently I've got the KW V2 coilover suspension installed and this is what I had on the car when they broke past weekend. They've been on the car for about 2 years and when they were installed not much attention was paid to detail around their adjustment other than to have the car stanced nice

When my halfshaft snapped it wasn't due to first occurrence wheel hop at that particular moment. I've been experiencing wheel hop every single time I was at the strip but I'd slightly back off throttle every time I felt it. Eventually it took its toll. I can attribute the actual breakage to 3 things:

1) Running 100% UT in 1st gear on Procede instead of 50% as usual creating a massive torque hit in 1st gear. I always used to decrease it to 50-75% before but decided to leave it at 100% this time around.

2) 6 puck ceramic clutch from Clutch Masters that's truly a piece of art and performs amazingly well. This thing will not slip no matter what you do, it'll GRAB and hold without a flinch. With the OEM clutch I am thinking since it was A LOT weaker than this ceramic one it'd allow slippage a lot of times and that way would relieve stress on the rest of the driveline.

3) Relatively weak OEM half shafts...really not meant for racing from a dig or burnouts, obviously

4) Lightweight flywheel from clutch masters...this is a 16lb single mass 2-piece flywheel. I'm extremely happy with its performance when it comes to acceleration in lower gears and really does the job amazingly well. I thought it was giving some vibrations into the rear of the car but I now realize it was because of a bad half shaft (the one that didn't snap, bad CV joint)...Lightweight flywheels provide for faster acceleration mostly in 1st, 2nd and 3rd gears and hp increases due to decreased rotational mass really are felt. I feel that having this flywheel also contributed to a more vicious wheel hop torque hit than what you'd typically encounter with the 38lb OEM dual mass flywheel

Given this situation and the fact that half shaft snapped NOT on launch but maybe 20-30 feet down the track after taking off due to wheel hop I'm looking to you for advice on how can this be addressed properly. I really feel that some form of procedural wheel hop tune-out needs to be done on these cars. Some members on this board may have already addressed this or at least tried to but I couldn't find any comprehensive discussion on the topic or potential ways on how to address it on this platform (other than "maybe" m3 rear suspension parts that I've ordered).

Having stickier tires (slicks or DRs) on the car doesn't "solve" the problem. It just moves the threshold of when wheel hop will occur around. For example, with the same DRs you may experience wheel hop if you launch at 3500rpm but not if you go higher, say launch at 4500rpm. However, you actually may wish to launch lower as you feel that your 60' would potentially be lower. Moving this threshold around with stickier tires or launch RPMs isn't a real solution to wheel hop and I'd really like to avoid discussing that particular item in this thread unless you feel its really relevant.

Shoot your opinions...wheel hop is bad and I really hope it can/should be cured on every car before you launch/take off hard again

EDIT: What happens when you launch like you "should" :
http://www.e90post.com/forums/showthread.php?t=444333

[BrianMN]

Is it as bad as this?

http://www.streetfire.net/video/must...ftw_739385.htm

[dzenno]

Originally Posted by BrianMN

Is it as bad as this?

http://www.streetfire.net/video/must...ftw_739385.htm

Almost

[Clap135]

I know of one way to reduce/eliminate wheel hop.

Run a taller tire on a smaller wheel. Wheel hop never happens when you over power the tires, it happens when you at the limit of traction just barely spinning the tires. By running a taller/softer tire on a smaller rim, the sidewall, espcially on a flat (compared to street tires) sidewall will greatly reduce the effect of wheel hop by absorbing it.

Pump your tires up to 50psi and run it on a stick surface, you skip your way through 2nd gear. Run a road slick, you will skip your way through 2nd gear, run a snow tires, you will not hop. Run a low profile drag slick, you will hop, run a high profile drag slip and you wont.

There are many "solutions" to this that aid the problem, however tires are the most important imo.
1. Stiffer bushing in the entire rear suspension
2. Dampers that are set correctly will help. Don't ask me what correctly is, good luck trying to figure it out lol
3. I believe I even heard of a rear sway bar helping out, I am just not sure if removing it completly was the solution of adding a stiffer one was the solution.

To sum it up, outside of tires, its a bitch to get rid off.

[Irishace]

Originally Posted by BrianMN

Is it as bad as this?

http://www.streetfire.net/video/must...ftw_739385.htm

I know this is a serious topic but I found that video friggen impressive/hilarious, that was some serious wheel hop, wow.

[dlbrooks18]

I don't have any wheel hop with my Quaife LSD and could be attributed to my upgraded control links that I had installed by HP Autowerks:

http://www.hpashop.com/product.sc?pr...categoryId=176

http://www.hpashop.com/product.sc?pr...categoryId=176

[dzenno]

Clap135, I ran 274/40/17 MT ET DRs on 17x8 (not even 8.5 as recommended) rims at about 17psi...this would be a pretty tall sticky tire and still got wheel hop..this didn't help..what about higher pressure

[Mr. 5]

Originally Posted by dzenno

Clap135, I ran 274/40/17 MT ET DRs on 17x8 (not even 8.5 as recommended) rims at about 17psi...this would be a pretty tall sticky tire and still got wheel hop..this didn't help..what about higher pressure

I'm sure you meant 275 but you're right, that's a pretty tall tire for our setup.
That's the same as what I've used and had no wheel hop. I run about 20 psi in the tires.

I think I might no what the problem is...
I bet you are warming up your tires in 1st gear huh?

[dzenno]

275 right, sorry, iPhone keyboard...

In 1st gear, yes, why?

[Mr. 5]

Originally Posted by dzenno

275 right, sorry, iPhone keyboard...

In 1st gear, yes, why?

I think your tires aren't getting hot enough and that's why they are hopping.
They are hopping because they are losing traction.

This is what I do:

-2nd gear burn outs are a must. The faster the tire is going, the hotter the tire is going to get.
-I launch and then get right on my brake and just sit there. Since you are in 2nd gear, your tires will be doing 60+ in place instead of 35+.

I've never had an issue with wheel hop.

[dzenno]

Mr. 5 what suspension are you running?

[dmurray14]

Originally Posted by Mr. 5

I think your tires aren't getting hot enough and that's why they are hopping.
They are hopping because they are losing traction.

This is what I do:

-2nd gear burn outs are a must. The faster the tire is going, the hotter the tire is going to get.
-I launch and then get right on my brake and just sit there. Since you are in 2nd gear, your tires will be doing 60+ in place instead of 35+.

I've never had an issue with wheel hop.

You're just doing a standing burnout in 2nd? I would have thought you would just end up burning the clutch....never tried though. Interesting.

[BrianMN]

Originally Posted by dmurray14

You're just doing a standing burnout in 2nd? I would have thought you would just end up burning the clutch....never tried though. Interesting.

+1. Never thought about dropping the clutch in 2nd.

[Mr. 5]

Originally Posted by dzenno

Mr. 5 what suspension are you running?

I'm running BMW performance suspension with M3 rear sway.

Originally Posted by dmurray14

You're just doing a standing burnout in 2nd? I would have thought you would just end up burning the clutch....never tried though. Interesting.

Yep, you'll be surprised with what you can do in that water box.
It's so slick in that place to begin with and then when you add the amount of torque were putting down, it's a no brainer to burn out in second.

I learned a while back with my e46 M3. I was having a hard time hooking up and then I talked to an old school guy at work. He said to burn out in a higher gear and it should fix the problem.
I went to the strip again and did exactly that and bettered my 60 ft by .3.
The rest is history.

What am I doing? I'm giving away all my secrets. I have a record to keep. lol

[Irishace]

Very intersting Mr.5, really great feedback on this. I may even try a 2nd gear burnout with my AT. I struggle with burnouts even with my AT.

[dzenno]

at the track I go to they strictly tell you to just clean off tires with one quick throttle kick in the water box, then they tell you to move up from there where it's dry and burn out...they get really upset if you burn out in the waterbox..I don't get it..

EDIT: Mr. 5, BMW performance suspension is just springs right?

[Mr. 5]

Originally Posted by dzenno

at the track I go to they strictly tell you to just clean off tires with one quick throttle kick in the water box, then they tell you to move up from there where it's dry and burn out...they get really upset if you burn out in the waterbox..I don't get it..

EDIT: Mr. 5, BMW performance suspension is just springs right?

If you have water on your tires, you can do the second gear burn out.
BMW perf comes with springs and dampers.

[dzenno]

On tischer's site they have 2 BMW perfect suspension kits..which one did you end up getting and how long have you had it on the car?

My kw v2 probably require adjustment after 2 years

[Mr. 5]

Originally Posted by dzenno

On tischer's site they have 2 BMW perfect suspension kits..which one did you end up getting and how long have you had it on the car?

My kw v2 probably require adjustment after 2 years

I got the dampers first which I believe is this:
http://www.trademotion.com/partlocat...catalogid=4462

and then got the springs afterwards once they came out.

[OpenFlash]

I don't know if this is pertinent to the problem but I always found ceramic clutch disks to bite way too abruptly. Which leads to excessive stress downstream in the system. They are great for road racing conditions where they can take a lot of heat and never slip between gears. But going from 0 torque to big torque instantly (at a launch) can shock the rest of the driveline badly. I've got over a hundred max power launches (slicks, 20psi, race+meth) and have yet to break a drivetrain component. Even my orginal clutch lasted 60k miles before slipping in 4th gear. Upgraded with a Spec stg 2 with light flywheel since then. I'm sure a bent/broken axle is somewhere in my future but I think keeping things somewhat pliable (organic disk, flexible drag tires, etc,) has helped a bunch.

Shiv

[cstavaru]

I have some friends who race regularly with heavily modified BMW e30 cars (350-500whp). They solved this problem by replacing the rear subframe bushings which were too soft, with very stiff bushings. I think that M3 subframe bushings may help alot in the e9x case.

[Dr G13]

Is wheel hop not influenced greatly by the road surface?

I mean I get wheel hop on flat smooth hot dusty surface but never on roads with stones embedded in them to help wet water traction. Just a thought.