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-   -   Front End Vibration (http://www.clubcobra.com/forums/backdraft-racing/139438-front-end-vibration.html)

Brian John 09-19-2017 01:19 PM
Front End Vibration
 
So my car has developed a terrible vibration in the front end, between 40 and 70 MPH.

Took the car to a decent shop recommended by local Cobra club members (CACC).

Shop just called they checked tire balance, they checked tires for out of round. What they said was they took it in and out of the shop several times and finally discovered that the front tires were not centered on the hub. I was told there is a spacer used on the hub to space the wheels out and this was causing the problem. Without the spacer, the wheels would rub on the disc brakes. They removed the knockoffs (fake knockoffs) and visually centered the tires tightening one lug slightly at a time spinning the wheel and checking that the tire was centered and working around the rim until all lug nuts were torqued.

They now tell me they have to leave the knocks off as they mount from the rear.

Anyone heard of this or had this issue?
Anyone familiar with the need for a spacer?

Any suggestions for a permanent resolution?

FWB 09-19-2017 03:04 PM
with the limited info provided it sounds like the wrong backspace wheels for your car

Brian John 09-19-2017 04:22 PM
More information

It is a spacer issue. The Tire Shop removed the knockoffs which allows you to see how the front wheels mount on the spacer. Presently there is an even gap maybe 1/32" evenly spaced. If I was to remove the wheels and reinstall with no thought to visually centering the wheels, the upper part of the hub would sit on the spacer and the bottom gap would be 1/16".

Question I have, are spacers standard for BDR's?
Are different spacers available or will I have to have some machined?

mln385 09-19-2017 05:01 PM
Quote:
Originally Posted by Brian John (Post 1430551)
So my car has developed a terrible vibration in the front end, between 40 and 70 MPH.

Took the car to a decent shop recommended by local Cobra club members (CACC).

Shop just called they checked tire balance, they checked tires for out of round. What they said was they took it in and out of the shop several times and finally discovered that the front tires were not centered on the hub. I was told there is a spacer used on the hub to space the wheels out and this was causing the problem. Without the spacer, the wheels would rub on the disc brakes. They removed the knockoffs (fake knockoffs) and visually centered the tires tightening one lug slightly at a time spinning the wheel and checking that the tire was centered and working around the rim until all lug nuts were torqued.

They now tell me they have to leave the knocks off as they mount from the rear.

Anyone heard of this or had this issue?
Anyone familiar with the need for a spacer?

Any suggestions for a permanent resolution?
Lets back track for a second here, what if anything has been done or changed prior to the vibration? Did this just start out of the blue or have the tires been off the car and then the vibration was noticed. If the car has been running fine and now all of a sudden it is vibrating if it is the spacers then perhaps they have to be installed in a certain sequence or placement.

Brian John 09-19-2017 06:45 PM
Quote:
Originally Posted by mln385 (Post 1430571)
Lets back track for a second here, what if anything has been done or changed prior to the vibration? Did this just start out of the blue or have the tires been off the car and then the vibration was noticed. If the car has been running fine and now all of a sudden it is vibrating if it is the spacers then perhaps they have to be installed in a certain sequence or placement.
Had some engine work done during that process that tires were removed, it was after the vibration was noticed. Tires balanced checked everything we could under the front end.

That is when I decided to take the car to The Tire Shop (their real name)

They checked everything they could think of and then noticed the tires were SLIGHTLY off center. They mounted them by visibly centering them no issue, removed and installed with no thought to centering them vibration. Re-centered and the problem went away. You can slide very thin flat blade screw driver between the rim hub and the spacer collar.

The issue is, one I do not have the knockoffs on the rims and two not the way to operate.

joyridin' 09-19-2017 07:20 PM
This is a pretty easy fix for any small machine shop. Take a rim and the spacers and they can make you a sleeve to fit over the adapter hub to the size of the rim pilot ID. They may have to machine them down a bit, but not hard.

When you use older Ford 8.8 rear axles and want to install disk brakes, you have to make a sleeve so the rotors do not flop around.

Ozzie Goat 09-19-2017 07:33 PM
If you're talking Backdraft, and OEM wheels, then this doesn't make any sense.

I believe the assembly instructions mention never use spacers of any kind.

Reminder: the hubs should be BMW hubs, and the offsets are well known. Having said that, based on the year of your BDR - there were variations

So, are these Backdraft wheels ? maybe pictures

EDIT: having said all that, I have an adapter on the front for the pin-drive hub adapter.

Brian John 09-19-2017 07:35 PM
I thought there might be an BDR part, but was considering a machine shop there is a Machine shop near my office.

Over the years I have used several machine shops in my job, but as the old timers retire there does not seem to be a crop of young guys taking up the trade.

GLS-BDR226 09-19-2017 08:38 PM
Quote:
Originally Posted by Ozzie Goat (Post 1430578)
If you're talking Backdraft, and OEM wheels, then this doesn't make any sense.

I believe the assembly instructions mention never use spacers of any kind.

Reminder: the hubs should be BMW hubs, and the offsets are well known. Having said that, based on the year of your BDR - there were variations

So, are these Backdraft wheels ? maybe pictures

EDIT: having said all that, I have an adapter on the front for the pin-drive hub adapter.
I have pin drive adapters that were added after I converted from bolt on wheels to true knockoffs. When I had the bolt on wheels there were not any spacers.

Gaz64 09-19-2017 08:45 PM
Quote:
Originally Posted by FWB (Post 1430565)
with the limited info provided it sounds like the wrong backspace wheels for your car
Can we have some photos please?

Spacers with no concentric step, or wrong step size to wheel is not a good start.

Gary

Brian John 09-20-2017 05:41 AM
I am traveling north for a few days and will send pictures when I return.

Sledge 09-20-2017 08:20 PM
Brian:

Your information says your Cobra is a B&B, yet you are saying it is a BDR. Could you kindly confirm which Cobra you have? I have BDR 168 with fake knock-offs and have never experienced your described problem, and don't have any spacers between the hub and the wheel. In nearly 50,000 miles I have had the wheels off and on a bunch!

cbreez 09-21-2017 09:23 AM
Google "hubcentric" and read up a bit for your answer...

Turner Motorsport and Ebay may be some sources for what you need. ;)

Brian John 09-21-2017 06:14 PM
Quote:
Originally Posted by Sledge (Post 1430625)
Brian:

Your information says your Cobra is a B&B, yet you are saying it is a BDR. Could you kindly confirm which Cobra you have? I have BDR 168 with fake knock-offs and have never experienced your described problem, and don't have any spacers between the hub and the wheel. In nearly 50,000 miles I have had the wheels off and on a bunch!

I own a B&B and a BDR

Brian John 09-21-2017 06:52 PM
Quote:
Originally Posted by cbreez (Post 1430640)
Google "hubcentric" and read up a bit for your answer...

Turner Motorsport and Ebay may be some sources for what you need. ;)
Thank you, surprised the tire shop did not know this.

cbreez 09-25-2017 08:04 AM
Thanks and good luck.


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