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I used to run 7mm Future Classic spacers up front with -2.5° camber that was adjusted via LCA shims.
I now run Tarett top mounts which allows for using less shims, so now I use 15mm Future Classic spacers with the OE wheels and -3° camber.
Just curious, if you're using a stud kit, why do you need the prongs on the spacers? What will 5 prongs do better than 3 prongs? I have 7mm spacers in front and have never thought about this before and would like to know more about your thought process. I'll be doing some maintenance this weekend and can check what mine are.
A good question, and some good discussion on this thread! First, several members mention using 5 or 7mm spaces, no issues. That certain makes sense because the center hub on our cars extend out probably 13mm or so from the hub wheel mounting surface. So with a 7m spacer, there is still enough center hub exposed to help center the wheel onto the car, then then attach the wheel bolts or nuts (if a stud kit used). I'd use a 7mm flat spacer, with no worries.
The issue comes if you want to use a 15mm spacer. Using a flat 15mm spacer will result in having no center hub to rest/center the wheel onto, before attaching bolts/nuts. Not only is it more difficult to mount the wheel (especially if using factory or extended lug bolts), but you don't have the benefit of the centering of the wheel to the hub. For me, I'd like to have a centering hub, or if using a thick spacer, a spacer that has a centering hub flange. That way, you know the wheels is centered properly before tightening down the 5 lug bolts/nuts. Some style of lug nuts are designed for lug centric use, thus not relying on the center hub for accurate positioning of the wheel. Trailer wheels come to mind. I believe some oval track racing wheels use a 45 deg taper on the cone nuts to better center the wheels properly. Regardless, given the choice, I think better (for vibration, safety) to use a hub centric mounting method. Aftermarket wheels often are made with a over large center bore hole, then use a plastic hub centering ring in the middle to adapt the wheel to different size vehicle hub diameters. So, having the center hub adds accurate mounting of the wheel, and maybe a bit of strength. All of the strength of the wheel to hub mounting surface is created by the torque of the lug bolts/nuts. Major clamping action, and proper torque on nuts is critical.
Oh, the issue is not whether a 5 prong hub is better than a 3 prong hub, but rather that a wheel spacer designed to fit onto a 3 prong hub will not fit a hub with 5 prongs. Rennline has some nice spacers, very much like the Numeric Racing spacers, utilizing a 3 prong centering hub design, however, no 5 prong design apparently: Porsche 5-30mm Wheel Spacers (rennline.com)
An update on my search for wheel spacers for my '21 GT4: Was looking for good quality wheel spacers in the range of 3mm to about 10mm in thickness. Spacers with a machined center hole fitting a 71.6mm hub, and if possible, a center lip to help center the wheel when installing (really nice when using wheel bolts, less critical if wheel studs installed). I found 1mm thick spacers from Elephant Racing, nice for very small adjustments, great quality, work fine. In the 3mm size I tried Numeric Racing spacers (flat design, hub centric, no center hub wheel lip), nice quality, works fine. From Future Classic Parts I tried their 3mm and 7mm thick spacers, excellent quality, hub centric, no center hub wheel lip. Worth noting, Numeric Racing makes a 7mm thick spacer, hub centric, with a center hub wheel lip to center the wheel but is designed for Porsches with the "3 finger" style of center hub. I unfortunately have the "5 finger" style of center hub so it didn't work. However, this type of design was what I wanted for the 7mm and 10mm size spacers. Eventually, I found a company, 4WheelSpacers, that seemed to make what I wanted, with a center hub lip, but only in 10mm and thicker sizes. I ordered a set, they were backordered, but after 1.5 months they arrived. I am very impressed with the quality and detail in these spacers. Customer service was also excellent, and they kept me updated on the arrival date. I needed a 10mm spacer for some rear wheels (19x11, ET55), was stacking a flat 7mm and 3mm, with the car's center hub (5 fingers) barely sticking out from the 10mm of stacked spacers to help center the wheel bore. With the new one piece spacers, wheel center bore is positioned with good overlap, all fits great! Pics below of it all:
Stacked 7mm and 3mm spacers
Above pic of the combined 7 & 3 mm spacers, the ends of the "5 fingers" barely protruding past the stacked spacers. Very nice flat spacers though.
Victor Equipment 19x11, ET55, for rears.
Above pic of my Victor Equipment 19x11 rear wheels. The ET55 was too high of an offset for the 295 or 305 tires I wanted to run. Stock is ET50. My primary autox rear wheels are BC wheels with ET47. The Victor wheels were very inexpensive, good for an extra set of wheels, but needed spacers to work on my car. A 10mm spacer works well on my current 305/30-19 RT660 setup. I needed to be aware of the close fit not only at the fender lip to the outer tire edge, but also the inner wheel lip to the rear toe links clearance. Not much wiggle room in rear tire/wheel fitments. Seems everything is pretty tight clearances whether inside or outside.
Ahhhh, above pic is the wonderful 4WheelSpacers product. Note the cutouts for the 5 finger center hub style of the GT4. The spacer's centering hub allows the wheels to easily position when fastening bolts/nuts. This was the only company I could find that offered wheel spacers of this design. Others may exist, but this is the only one that responded.
Above pic of the backside of the spacer. Nice design, the stock 5 fingers fit perfectly into the openings. I don't feel the wheel is supported by the centering hub, whether the car hub or the spacer hub, but definitely centers the wheel. The surface contact created by the torque of the wheel bolts/nuts, in my opinion, is where the primary support of the wheel occurs.
Above pic, the 4WheelSpacers spacer fitted to the car, fits wheel fine, and for those without a stud kit installed, these spacers come with a set of very good quality extended bolts.
Hopefully this info will help some others in shopping for spacers. Especially if getting into the 15mm or wider spacers I think this style is really a benefit. Cost is pretty comparable to a plain flat spacer.
just installer the 8MM on my fronts... wheels sit nice and flush. 4WheelSpacers had great customer service. im very happy withe the look and quality
AtoB, I was going to PM you on this but figured it might be worthwhile to confirm it in this thread for anyone else who may look at this in their spacer quest. Was yours the "POR08KT" kit on the 4wheelspacers site? Asking because their site only shows Caymans up to 2020, makes no mention of 3 prong vs 5 prong, and the picture (which I realize might not be of the actual spacers) seems to show cutouts for 3 prong axles, not 5 like us GT4/Spyder/4.0 GTS guys need.
Would be very helpful to know the POR08KT kit works for us.
I think this is even more relevant now since like Future Classic has appeared to go radio silent on folks including myself.
I used to run 7mm Future Classic spacers up front with -2.5° camber that was adjusted via LCA shims.
I now run Tarett top mounts which allows for using less shims, so now I use 15mm Future Classic spacers with the OE wheels and -3° camber.
What does this look like? Any rubbing? I had -2.0° up front with shims then got taretts as well and now they're at -2.8°. Looking to run 11-12mm of spacing which seems like it'd be okay given your setup...
Does installing front wheel spacers only negatively or positively impact handling in any way?
If one only use small spacers, such as under 10, there should be no impact. However, a slightly wider track may improve handling to a very tiny degree.
07-25-2022, 05:38 PM
