[abhibh]

Hi,

One of cousin who owns a corsa 1.6 recently like 2 weeks ago got Mechilin certis and new 13 inches alloys for his ride. Now the problem is as soon as he reahces 100 - 120 and gets his foot off the accelerator pedal the stearing shakes / vibrates but if he keeps on pressing the car runs smooth. ??

Also will these hub-centric rings help in this specifinc problem ?

Thanks.

[sAP]

Abhibh:

I am not sure what is causing the vibration to dissappear during acceleration and re-appear when coasting in that range. But its a good idea to tackle any kind of vibration issues caused immediately after a switch to "alloy wheels" by the following thumb rules:

• wheel centering is off, install centering rings
• if you haven't already balanced your wheels before installation, get that done
• rebalance the particular wheel each time the tire is taken off the wheel, as in the case of a puncture (not required when the wheel is merely taken off the car or rotated)

A wheel allignment job is not necessary. It is a misnomer because allignment is actually done to the hubs of the car, not the wheel. So unless you remove the hubs (as in brake rotor change) or hit the kerb badly (or a really deep pothole at speed), you don't need to re-allign.

Hope this helps.

sAP

[sAP]

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

On the first post of this thread (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.

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, even on threshold-level braking from 160km/hr.

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.

So then, I got my alloy wheels off immediately (K-speed 13" with centering rings and all) and installed my stock Corsa wheels (13" steel wheels). 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.

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 (F61530 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.

Here is a summary:

1. Installed K-speed 13" alloys on stock tires, wheel vibrations occured at high speed (> 110km/hr)
2. Installed centering rings, high speed vibrations dissappeared
3. After 7000kms, brake shudder set in
4. Replaced brake disc, pad and fluid. No brake shudder initially.But on repeated high speed testing, brake shudder started to creep in
5. Installed stock wheels, no brake shudder even on repeated testing
6. After being bored with stock wheels, installed Aura alloys matching original hub-dia, rim-width and offset
7. No brake shudder on repeated high speed testing

So now, you can make your own verdict. The results can't get much more obvious than this. If you have any questions, please post them here. I will try and answer as much as I can and know about.

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

sAP

PS: In case you are wondering where all this testing occurs in a place as crowded as chennai, it occurs on the Chennai-Tambaram bypass -- which is basically a 19.5km stretch of toll road that is closed off on both sides with railings. Can't get much safer than that. 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).

[rks]

Very informative report, sAP. Shoud be an eye-opener for those who take the plunge with after-market alloys. Company-supplied alloys, even if more costly than after-market ones, are anyday worth it simply because they are guaranteed to be a good match for your car. If company-supplied alloys are not available for your car, it is advisable to think a thousand times and act wisely; if in doubt, stick to the stock steel rims. Because the guys who sell and fit the after-market alloys have absolutely no expertise and are mainly interested in making a quick buck. I made the decision to stick to my stock steel rims in my Santro, but went for stock-size tubeless tyres (S322) as compared to the earlier tubed S322 tyres. After reading this thread and especially your latest post, I think I made a wise decision, even though I was seriously tempted by the shiny and great-looking alloys on offer.

[nitrous]

SaP,nice report.
PS:With all those ultra high-speed brake tests, ur soon gonna need a new set of tires. How about an upsize? 15inchers ok??

[santosh.s]

Originally Posted by sAP

If you have any questions, please post them here. I will try and answer as much as I can and know about.

A dumb question-
why do you think alloys which do not cause any high speed vibrations, are culprits in brake shudder problem? I mean could you really get to the root cause of the problem and based on that justify that stock rims or your new alloys won't cause the same problem again? Did you check rear drums as well? (unless you have all disks). I am asking this because I believe drum brakes are susceptible to such problem. IMHO, the origin of the problem is most likely to be associated with brake shoes/drums (or disks, which seem to be ruled out), followed by rest of the braking system, and then rims/tyres (very unlikely). If I remember correctly, you have a sail and I presume it doesn't have ABS.

[sAP]

I guess what you are asking Santosh, is that if I did not have vibration issues at high speed, how come I am having brake shudder issues?

Frankly, I don't know. I was under the impression that if I don't get vibrations or wobbles at high speed, everything was going to be okay. And it was okay for a while too.

But after about 7000kms, brake shudder started to happen.

It cannot be the rear drums or shoes because if that was the case, I'd still be having shudder because I haven't replaced my drums or shoes. (I have only replaced the front discs and pads)

There is however a possibility that re-bleeding my brakes has solved the problem (due to air bubbles being trapped in the lines). But that can also be ruled out since even after re-bleeding and testing, though it was smooth at first, brake pulsation started to set in slowly after 3 or 4 test runs on those alloys, which vanished completely on running stock wheels.

I am not sure if brake shudder will start to happen again at a later point of time with my new alloys or stock rims. But I can tell you that if I still had my previous alloys in, what had already started to creep in during testing would have brought me neck deep by now.

I am not saying that all aftermarket alloys are necessarily bad or that this scenario will reflect on all types of vehicles. Just that this is my experience and that hopefully somebody out there might benefit from it while facing a similar situation.

Hope this answers your question.

sAP

[drifter]

You know whats funny.....im experiencing similar brake shudder after about 30000kms of running on my accent with 15inch alloys. I shall also try refitting to stock as soon as I get the chance.

Drifter

[sAP]

Thanks RKS and Nitrous.

Nitrous, I ruled out 15 inchers after I personally spoke to a SAIL owner in Chennai (Rahul) who got 15" alloys that required him to swap out his rear springs for a stiffer import eibach set. Else, the lateral protrusion created by the offset of his rear tires were messing with the rear wheel arch while seating two adults at the back seat. But I guess an offset of 45mm might work because 15x7" is what European owners get as stock rim sizes on their Corsa "B"s.

But more so, I figured I spent more practical time running over road irregularities than what a 3.6" sidewall could afford me on a 195/50R15 size tire. So I am basking in the comfort of my current 4.8" sidewall.

RKS, how is your experience with the tubeless S322? Do you find any difference in the driving experience? Also, what is your take on support issues if you need to fix a puncture?

sAP

[sAP]

Originally Posted by drifter

You know whats funny.....im experiencing similar brake shudder after about 30000kms of running on my accent with 15inch alloys. I shall also try refitting to stock as soon as I get the chance.

Drifter

Drifter: The bad news is that you need to get new front rotors (brake discs) like I did before you swap back to stock wheels. Your existing rotors will already have warped or have lateral runout.

sAP

[rks]

Originally Posted by sAP

RKS, how is your experience with the tubeless S322? Do you find any difference in the driving experience? Also, what is your take on support issues if you need to fix a puncture?

The tubeless S322 has much better grip and makes virtually no noise, as compared to the tubed version. This becomes evident on the highway -- you can take corners much faster and with virtually no noise from the tubeless tyres. Under rainy conditions, the superior grip offerred by the tubeless tyres translates into much better handling at high speeds -- here I am admittedly comparing my old tubed tyres with the brand-new tubeless ones, which is an unfair comparison. Still I feel that tubeless tyres are a class above similar tubed ones under rainy conditions.

As far as punctures are concerned, I have a compressor (operated from the cigaratte lighter outlet). So I just plan to fill up and drive to a properly equipped puncture shop. This is the great advantage of tubeless over tubed ones-- the punctures will generally be slow and I believe you can drive on for hundreds of kms with a punctured tyre.

So far my tyre pressures are holding very well -- no air leakage from the steel rims. You have to be very careful while negotiating big potholes-- if you hit them hard, the steel rims can get bent and leak out air suddenly. The other point is that over time, the air can leak out due to rusting of steel rims, or from the valve stem area, but again this will be a slow leak and will give you enough time to take corrective action.

[sAP]

Originally Posted by rks

As far as punctures are concerned, I have a compressor (operated from the cigaratte lighter outlet). So I just plan to fill up and drive to a properly equipped puncture shop.

Makes sense. Good strategy, rks.
sAP

[sukiwa]

I changed to aura alloy wheels(A61350) & Tubeless tyres (Goodyear GPS2) same day I bought car (santro xing xo). Started getting vibrations after going beyond 80 kmph after initial running-in of 800 Kms. Google search led me to this site & thread.
Wheels dealer did wheel centering on front wheels, tested it beyond 80 kmph, vibrations looked to have stopped but re-appeared after couple of hits to 100 kmph. Again went to wheels dealer, he swapped front right & rear left, moved front left to rear right and stepney to front left. He did this as he felt front wheels were taking too many weights for centering. Again took the car for testing with his mechanic, little vibrations were felt but not to the extent felt earlier. I am not sure whether problem has got resolved completely, can confirm only after a trip on pune-mumbai expressway.

Two questions:
What's hub dia. for santro xing? Wheel dia. for aura wheel(model A61350) seems to be 56 mm or so (didn't get correct tool for exact measurement).
If hub. dia. matches wheel dia. then it will not require any hub rings. But, if vibrations persists, then what could be issue? Will these vibrations at high speed create any problem for suspension or any such?

------
Santro Xing XO
Oct 2006

[sAP]

Sukiwa: By the word centering, I think you meant balancing (where you said the installer centered the wheel over and over again).

Concerning your set of questions, I don't know what the hub-dia is for a Santro. I know that it is 56.5mm for my Corsa and that the F61350 version I bought matches my hub perfectly without any *play*. (I say version because there are different versions of the same Aura wheel model for different cars)

Concerning your 2nd set of questions, you might have to peruse through several posts in this thread and others to arrive at your own inferences. But to put a long story short, if wheel vibration goes unchecked, you can probably expect warped brake rotors like I had (which leads to severe brake pulsation over time) and possibly premature suspension & steering linkage wear, if not outright damage.

If I were you, I'd first try the following on one wheel at a time -- remove all 4 wheel lugs, hold the wheel against the hub, turn the wheel on it, move it about and look for any *play* in the centering. If there is no play, then I would try to get all wheels rebalanced at an alternate tire dealer to rule out the possibility of an inaccurate balancing machine; and then take it up from that point.

Well, there you go. Good luck.

sAP

[gdhiraj]

Whats the PCD, Offset and OD for Optra ? I am planning to go for HIJOIN 15 Inch and the dealer tells me that he carries some models which will fit my optra with a PCD of 114... we have not talked about Offset at all .. has anyone tried HIJOIN in optra ? i am worreid about vibrations ?