Slip on vs bolt on spacers?

[SVTMatt]

For this year's winter project I'm going to tackle getting the GT350 ready to use the Apex EC-7 wheels with Michelin Pilot Sport Cup 2's. Pretty much I'm copying @VoodooBoss 's information from the Rotatable GT350 Square... thread. Btw thanks for all the details there.

The GT350 is also getting the lowering springs installed by a local race shop. And while talking to them let to the question of what kind of spacer to use. I have no idea. When searching around online there's all kinds of answers. But I didn't see anything here, where I find the best info.

When making a choice what information is needed to make the best choice for the GT350s?

 

[TMSBOSS]

Slip on if used with a high grade wheel stud is preferred. Be sure to use a hub centric spacer as well. Bolt on gives you the potential of having 10 weak bolts.

 

[ArizonaBOSS]

Bolt-on spacers should not be utilized for track cars.
Switching to ARP wheel studs (or to GT350R hub/stud assemblies) is the recommended route.
Then you can run some large slip-on spacers and have plenty of thread engagement on the studs.

 

[85Gold]

I am using 20mm slip on spacers and ARP studs with the Apex wheels and have no clearance issues with 305 NT01 square setup.

I know most are running 25mm spacers so I am just putting out another data point.

Peter

 

[Black Boss]

"Bolt-on spacers should not be utilized for track cars.
Switching to ARP wheel studs (or to GT350R hub/stud assemblies) is the recommended route.
Then you can run some large slip-on spacers and have plenty of thread engagement on the studs."
+1.

@SVTMatt To run square you'll need 25-28mm spacers up front if you want to run 315's. 25mm is commonly available and will work with either ARP studs or the GT350R hubs. 28mm replicates the R front wheel offset exactly, but 26-27mm is about as much as you can go with the ARP studs to retain full thread engagement. A 28mm spacer really needs the longer studs on the R hub for full thread engagement.

These guys sell custom thickness hub centric spacers at reasonable cost:
http://www.motorsport-tech.com/wheel_spacers.html

 

[bpracer]

Edit - Ha, what he said ^^^

http://www.motorsport-tech.com
$135 shipped for hub-centric spacers with lightening holes. Took a little more than a week because each are custom made.

I went with 28mm spacers as that would match the R model wheel spec. Probably will have all this together next week.

If you want lightening holes, call Lenny (owner) directly, as that doesn't show up with their online ordering form. Very good service for me.
775.351.1000

 

[ls110]

Black Boss & Arizona - Both of you are opposed to the bolt-ons. Share your thoughts on this. I am running 30mm rear bolt-ons and your input will help me pay attention to any potential failures. Guessing you are likely concerned about added risk of bolt failure. The reason I have heard for using the bolt-ons for 1" plus spacers is to reduce the flex potential of being farther out on the studs.

 

[Black Boss]

Black Boss & Arizona - Both of you are opposed to the bolt-ons. Share your thoughts on this. I am running 30mm rear bolt-ons and your input will help me pay attention to any potential failures. Guessing you are likely concerned about added risk of bolt failure. The reason I have heard for using the bolt-ons for 1" plus spacers is to reduce the flex potential of being farther out on the studs.

I'd worry about doubling the number of failure points with bolt ons. Hub centric spacers will reduce eccentricity and eliminate lateral/vertical flex, leaving only torsional flex, which shouldn't be an issue with correct torque specs.

The front studs on the R are 3 3/4" long to accommodate the very thick hubs on the carbon wheels -- the equivalent of running 30+ mm spacers on regular wheels. Although those studs are 14mm, they are not ARP's.

Hope this helps.

 

[RES_22]

Lenny is awesome...I bought two sets from him...excellent quality and service.

 

[ls110]

I'd worry about doubling the number of failure points with bolt ons. Hub centric spacers will reduce eccentricity and eliminate lateral/vertical flex, leaving only torsional flex, which shouldn't be an issue with correct torque specs.

The front studs on the R are 3 3/4" long to accommodate the very thick hubs on the carbon wheels -- the equivalent of running 30+ mm spacers on regular wheels. Although those studs are 14mm, they are not ARP's.

Hope this helps.

Yes that helps. Or maybe it doesn't help... as I now have ten more bolts to worry about....

 

[bpracer]

If the bolt-on spacers are aluminum, you essentially have an aluminum hub instead of steel. The head of your new wheel studs are held in place by aluminum. On your stock hub, the studs are pressed into steel. If the bolt on spacers are made out of steel, they are just heavy.

As the R front hub's studs are longer than any ARP stud, this is probably a rare occasion that you can actually use a hub-centric spacer that thick.

Apex had a photo caption stating they used a 1" spacer (25.4mm for those counting) on an R and used the stock lugnuts. I have my doubts as the R studs are LoooonnnG. I think the stock nuts might still bottom out even with 28mm spacer. I won't know until next week if it will all look factory when I'm able to get tires and new hubs mounted.

 

[ArizonaBOSS]

@ls110 in addition to the additional failure points, I'd also be concerned about the durability/fatigue strength of the studs attached to the bolt-on spacers. I haven't taken a close look at these but my bet is most of them are Chinese pot metal made for bolting 24s onto Escalades as opposed to motorsports abuse, compared with a real OEM solution in the GT350 hubs (for S550s) or qualified aftermarket solution like ARP studs (for both S550 and S197).

 

[SVTMatt]

Thanks for all the great info. Makes the decision process much easier. I'll be giving Lenny at motorsport-tech a calls in the near future.

 

[TMSBOSS]

I ordered through Lenny. He is a great guy. I called him to ask if he could expedite production and shipment. He asked me when I needed them and then said to keep my money, the fee to expedite because he would get them out to me early, no fee. Nice.

 

[Fabman]

 

[RaiderJatt02]

Edit - Ha, what he said ^^^

http://www.motorsport-tech.com
$135 shipped for hub-centric spacers with lightening holes. Took a little more than a week because each are custom made.

I went with 28mm spacers as that would match the R model wheel spec. Probably will have all this together next week.

If you want lightening holes, call Lenny (owner) directly, as that doesn't show up with their online ordering form. Very good service for me.
775.351.1000

Thanks for this. I just called and placed my order. Told him I found his info on TMO and he knew exactly what I wanted. Now I just have to wait for the R Hubs and wheels to arrive.