Spacers - the cause of my front end vibration?
 

I have a front end vibration after installing a new set of Jeff Alton wheels and 6.5mm spacers (sold on Pelican - to clear my brakes) on my 87 Carrera. I believe it is a problem with the spacers, specifically the hubcentricity (or lack thereof). They are not hubcentric - just a thin disc. I have a second set of Rota wheels to experiment with – ones that do not require spacers. So here is what I have done:

1. Alton wheels with 6.5mm spacer – vibration
2. Alton wheels with a thinner 5mm spacer from Zuffenhaus (in order to try to get closer to the hub center) - vibration
3. Rota wheels w/out spacer – no vibration
4. Rota wheels w/ 6.5mm spacer – vibration

I have had the Alton wheels road force balanced twice. I can’t try the Alton wheels w/out spacers because of my brakes. The 5mm spacers are only being loaned to me to try to fix this problem. So I attempted to krazy glue the 6.5mm spacers to the Alton wheels in order to make sure that the wheels are getting centered on the hub (I made sure the diameter of the spacer was flush with the center diameter of the wheel cut-out) and still had a vibration – reasons discussed here: http://forums.pelicanparts.com/porsche-911-technical-forum/480993-am-i-crazy-use-krazy-glue-bond-metal-metal.html?highlight=hubcentric

So now I am at a loss. The only thing left is to buy 15mm H&R hubcentric spacers and longer wheel studs (time and money). Any ideas? Custom hubcentric plastic rings? Tap and drill the spacers to the wheel (don’t know about this - the krazy glue still held after my test drive)? I am getting frustrated. Thanks.

Could take those spacers to a machine shop - they could check for flatness and surface grind them if the two sides aren't parallel.

can't help you on the vibration, but Porsche makes a 5mm spacer that is hubcentric that is used on the rear of the 997 GT3. They are not cheap, but as you can see, the center diameter is closer and rests into the hub. p/n 997.361.605.90

http://www.pelicanparts.com/cgi-bin/smart/more_info.cgi?pn=OEM-99736160590&catalog_description=Genuine%20Porsche% 20Part%3A%20WHEEL%20SPACER%20RING.



[IMG]http://www.***************/images/Porsche/Large/l_P914882.jpg[/IMG]

There are hubcentric spacers available in 7mm. They recommend (and supply) longer wheel studs, but if you have enough thread exposed you might get away using these with your existing studs. (I didn't recommend that, just to be clear). About $75 / pr. called H&R Trak+

http://forums.pelicanparts.com/uploa...1245987056.jpg

I had that problem on another car. I bought hubcentric adapter rings and it cured the problem.

http://www.justforwheels.com/index.jsp?cat=hubcentric&sub=how&track=GHR

Thanks - I have looked at the adapter rings but thought they would be hard to get in the right size. I may give that company a call. My front hubs are not stock - they are off of Steve T's 996 brake kit. I think they are 944 hubs but I will have to check with him...

Steve thanks for the 997 spacers - never thought of that. Do they have the same bolt pattern as our cars?

I have already installed longer studs for the 6.5mm spacers, so I want to avoid that route if I can again.

Thought the thinnest hubcentric spacer H&R sold was 14mm - I'll give them a call.

Their ads appear that way, but I believe they're talking about total track widening: 7+7=14

Bolt patterns should be all the same 5x130.

I had the same problem with spacers switched to the alton wheels problem solved. what brakes are you trying to clear?

Talked to H&R - the thinnest they have with centering flange is 14mm...

Looks like hubcentric rings or 997 spacers are the ticket. Waiting on measurements from Keith/Jeff for the rings. Those I think will have to be custom.

Or maybe I just order the 997 spacer and see if it fits.. I'll let you guys know how it works out.

Ben I am trying to clear 996 brakes - are you using spacers w/ Alton wheels or just the wheels themselves?

I have had the same problem with adapters which is one reason I don't like to use them. Don't know if the hub-centric ring would help an adapter but it is worth a try for those using them.

no spacers anymore just the alton wheels and I don't have the brake issue just 964 calipers for me

Just talked to 1010tires.com, a vendor that also sells hubcentric rings, and they said they do not recommend using their rings with spacers. He said the only solution would be to purchase hubcentric spacers with a centering lip. I may give the other website mentioned in this thread a shot. The problem is that the difference between inner and outer diameters is so small...

Steve do you know if the spacer you listed is merely hubcentric itself, or does it actually have a centering lip? Pelican is closed today - already tried.

Gotta get the dimensions of Jeff's wheels. May still give the rings a try but I think I may end up with a new spacer in the end...

The 997 spacer is just a ring and fits perfectly around the hub. There is no centering lip as it is physically impossible for any spacer under ~12 mm to have a centering lip. In order to have a lip, the spacer must be thick enough to protrude past the existing hub, and step down to create a center lip.

You should mic the spacer you have and see if there's any variations in the thickness that would cause out of true vibration. Also after mounting the wheel with the spacer on your car, make a jig with a coat hanger or metal bar, and point it against the rim of your car while you slowly spin it and observe or variations in trueness. From that you'll likely discover the cause of your problems.

Thanks Steve - I'll let you know...

If I were to get H&R spacers, which do I get (13-14mm). They have DR and DRS - what is the difference? They also don't have any specs for pre-89. Do they come with longer studs?