Part 2: Update to Solution for vibrations after installing alloy wheels

[sAP]

This is an update to wheel vibration/ brake shudder issues experienced on high speed cruising after installing alloy wheels.

On part 1 of this topic (http://www.team-bhp.com/forum/151614-post1.html), I mentioned about the need for "centering" aftermarket wheels by installing "centering rings" to reduce the effects of steering/ wheel vibration at speed. Also I mentioned how the vibrations dissappeared after I installed metal centering rings on all 4 wheels.

7000kms later after running on such a setup, I have more experience to share with discerning driving enthusiasts. The reason I have started this as a new thread is so that readers can quickly find this information by going to the first post of the thread.

In my previous long distance daytrip (~700kms), I experienced severe brake shudder when braking from moderate cruise speed (~130km/hr). The brake pedal would pulsate badly when high pressure is applied to the brake, causing passengers in the vehicle also to feel the shudder/vibration. At 160km/hr, it gets a little violent.

Since this was discomforting, I had the brake discs immediately checked for lateral runout and skimmed them to tolerance at a specialized lathe. This indeed helped because the brake shudder reduced considerably. However, over a period of time, it started to increase again.

So last weekend, I installed brand new sets of front brake discs (rotors), brake pads and re-bled the system with new brake fluid. Also, I checked for air bubbles trapped in the lines. After this was done, I took a test drive and found that there was no brake shudder at all in the beginning. However, my happiness didnt last very long. After several attempts over a high speed stretch, I noticed that brake pulsation was starting to creep in. Very slowly, but definitely creeping in.

I didn't want my new brake discs to start warping like my old ones. So I immediately got my alloy wheels off (K-speed 13" with centering rings and all) and installed my stock Corsa wheels (13"). Now, back to the high speed stretch and what an amazing difference there was. The stock wheels on a Corsa were brilliant as far as high speed cruising and braking were concerned! (And sucked as far as looks were concerned)

I tried running several times over, but the new brakes never showed a hint of pulsation or shudder. Verdict: You stand a very good chance of ruining your car by changing over from it's stock wheels.

Now then, a person who's been running on alloy wheels finds it very difficult to run on boring steel wheels. So yesterday I got a brand new set of Aura wheels installed (F61350 13" which is relatively new and not yet displayed on their website) and sold off my used K-speed set (KS315 13") to a used wheels dealer.

Why did I get Aura wheels? Because they were the closest I could get to my original steel wheel specification, which includes:

• an exactly matching center-bore for my car (56.5mm hub dia)
• an exactly matching rim width (5")
• an offset that matches my original (46mm)
• am anyway running original/ stock tires

In the looks department, the Auras don't stand a chance against my earlier K-speed set (which was a classic 5-spoke with a machined finish, which you can see in my team-bhp garage)

Well, I was back to testing this morning. Heavy braking from 150km/hr. No brake shudder! Tried several times over. Not a *hint* of brake shudder. And it wasn't creeping in either. Hopefully thats the last I have seen of wheel issues.

So here is a summary:

1. Installed K-speed 13" alloys on stock tires, wheel vibrations occured at high speed
2. Installed centering rings, high speed vibrations dissappeared
3. After 7000kms, brake shudder set in
4. Installed new brake disc, pad and fluid. No brake shudder initially, but it starts to set in slowly
5. Swapped to stock wheels, no brake shudder whatsoever
6. After being bored with stock wheels, installed Aura alloys matching original hub-dia, rim-width and offset.
7. No brake shudder whatsoever

So now, you can make your own verdict. If you have questions, please post them here. I will try and answer as much as I can or know about.

I have to add though, that the Aura's still don't feel as great as the stock Corsa wheels in the 160km/hr territory.

Hope this helps.

sAP

PS: In case you are wondering where all this testing occurs in a place as crowded as chennai, it occured on the Chennai-Tambaram bypass -- which is basically a 19.5km stretch of toll road that is closed off on both sides with railings. A multiple-entry ticket and securing your hand-baggage with a seatbelt is the way to go.

Tires were balanced each time they were mounted on the wheel. Tire pressure was maintained at 30psi-cold on each test (Opel recommends 29psi cold).

[sAP]

This thread is being discussed here instead http://www.team-bhp.com/forum/tyre-a...oy-wheels.html (Solution for vibrations after installing alloy wheels) (See post #63 & thereon)

sAP