| Author |
Message |
Mark Eberhardt (Me_k)
Member
Username: Me_k
Post Number: 377
Registered: 5-2002
| | Posted on Friday, January 17, 2003 - 6:08 pm: | |
Andeas, your welcome. Now it just so happens I have a supercharger for sale that will get you around 400HP. Feel free to shot me an email when your ready. |
Andreas Forrer (Tifosi12)
Member
Username: Tifosi12
Post Number: 304
Registered: 10-2002
| | Posted on Friday, January 17, 2003 - 5:47 pm: | |
Mark, YOU DA MAN!
Thanks much for all the explanations! I knew there was more to it and I would have gotten it wrong had I tried myself. Thanks again! Now I even barely understand the issue, barely.
Good, once I got the wheels squared away, we need to talk supercharging the engine. Remember me? Gotta get up to that 400+ HP range...
So, after I successfully hijacked this thread, back to your local news. The weather: |
Mark Eberhardt (Me_k)
Member
Username: Me_k
Post Number: 375
Registered: 5-2002
| | Posted on Friday, January 17, 2003 - 5:31 pm: | |
David, no a 308, like most ferraris is a 5x108, you need an adapter to use the 5x114, which fits perfectly when you have 45mm offset. The adapters cost about $75 each and should be hub-centric and let's you have a large selection of wheels that are not expensive.
Andreas, sorry, I assumed incorrectly. Ferrari quotes the number you posted too. That complicates things a bit, depending on what you want exactly. I think the first thing to do is calculate were the outside edge of the wheel is relative to your hub. In the front the track is 61.4�, that�s the center of the tire/wheel, so add the wheel width of 8� = 69.4�. The same for the 308 give 57.5+7=64.5� The stock offset is 11.5mm (~.5�), so the hubs are 64.5�-7�+.5�+.5�=58.5� apart. You have a choice now. The simplest, strongest, lightest thing to do is buy the right wheel. The other choice is to use you spacers and a wheel with more offset. Without the spacers, assuming 8� wheel, you get (58.5+8-69.5)/2= -1.5� or �38mm offset. With your 25mm spacer it would be �13mm offset. The minus means the hub is inside the centerline of the wheel, not the outside as usual. The rear calc or different width wheels works the same, just plug in the numbers. After you decide on a wheel width, you can pick a tire for it. For a 225/50-16 means the advertised tread width is 225mm, the side wall height is about 225x.5mm and it fits a 16� rim. Tiretack has a good listing of dimensions for different tires by brand and size and give the rim width recommendation. If you go 8, you�ll want about a 225/50, on a 10 about a 285/45. It varies some by brand though.
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Andreas Forrer (Tifosi12)
Member
Username: Tifosi12
Post Number: 298
Registered: 10-2002
| | Posted on Friday, January 17, 2003 - 4:52 pm: | |
Here are the track dimensions according to Forza:
83 308: 57.5 and 57.5 (front, rear)
288 GTO: 61.4 and 61.5
So we are talking about 4" difference front and rear. So 2" or 50mm on each wheel. Using my spacers (track widening kit) with 50mm front and 75mm rear, equaling 25mm and 38mm per wheel I think I still have 25mm and 12mm to go on the wheel offset. Correct?
I never quite understood tire sizes/dimensions, so what would I need assuming I'd got with 16" wheels? |
David M Nichols (David_nichols)
New member
Username: David_nichols
Post Number: 3
Registered: 1-2003
| | Posted on Friday, January 17, 2003 - 12:32 pm: | |
So the 308 uses the standard 114/5 bolt pattern? |
Andreas Forrer (Tifosi12)
Member
Username: Tifosi12
Post Number: 285
Registered: 10-2002
| | Posted on Friday, January 17, 2003 - 12:06 pm: | |
Mark, I posted my numbers from (leaking) memory. I have the exact numbers at home, they were in Forza's buyers guide. Anyway, I bought some track expansion kits for my front and rear (50 mm and 75 mm per axle). So I think I'm still about an inch off on each wheel, which I thought I'd compensate with the wheels. Problem is, I haven't bought the 288 fenders so I can't say for sure.
Obviously I want to get this all right before I order wheels.
BTW: Is there any advantage/disadvantage of using these spacer rings vs sufficient offset in the wheel to get to the GTO's dimensions? |
Mark Eberhardt (Me_k)
Member
Username: Me_k
Post Number: 374
Registered: 5-2002
| | Posted on Friday, January 17, 2003 - 11:42 am: | |
Andreas,
I'd have to double check, but I think it is much less than that. I have a GTO front valance on my car, it fits, but the top corners in front of the wheel had to be flexed in about 1". Which would make sense since the GTO front wheels are 8" instead of 7". So I think they just put all the material on the outside, the offest would be 12mm - 12mm (25mm/2)or zero. The GTO rear is 10" vs 8, so again I think they just put it on the outside making the offset 12mm-25mm(50mm/2) or -13mm. It may be more, but I don't think so. |
Andreas Forrer (Tifosi12)
Member
Username: Tifosi12
Post Number: 277
Registered: 10-2002
| | Posted on Friday, January 17, 2003 - 8:08 am: | |
Dare I ask the following question?
What wheel/tire size and/or offsets do you recommend for a 288 GTO rebody on a 308?
I think the front track is about 6" wider (3" each wheel) and the rear about 4", not completely sure though. |
Mark Eberhardt (Me_k)
Member
Username: Me_k
Post Number: 373
Registered: 5-2002
| | Posted on Friday, January 17, 2003 - 6:53 am: | |
David,
The wheels I'm using are ferrari 550. The front offset is 44mm, but I use a 25mm spacer(hub-centric), so 19mm. The rears are 32mm, they're good as is, no spacer.
For the previous set up, I bought 45mm offset with a 114x5 bolt pattern. Almost every style wheel made is available in that configuration, it fits the jap cars (rx7, supra, ...). I found a set I liked at tirerack for $200 each. Then I used a 25mm thick hub-centric adapter. So the net offset was 20mm, that worked out pretty well too. |
David M Nichols (David_nichols)
New member
Username: David_nichols
Post Number: 2
Registered: 1-2003
| | Posted on Thursday, January 16, 2003 - 11:42 pm: | |
thanks guys. Ill use the search from now on.
Mark what size offsets are you running with your setup? |
Mark Eberhardt (Me_k)
Member
Username: Me_k
Post Number: 365
Registered: 5-2002
| | Posted on Thursday, January 16, 2003 - 12:13 pm: | |
It all depends on the hoops you're willing to jump though. I am running 18x8.5 in the front. They go right on, I increase the offset to keep the outer edge basically stock. The rea is where the troubl is. I am running 18x10.5, again offset adjusted to keep the outer edge near stock. But I had to go to a 2.5" OD spring and move the lower shock mount 1.625" in. Just doing the spring, 18x9 will go. Nick sells a set of shocks with a 2" ID spring and says 18x9.5 will go. I run 225/40 in front and 285/35 rear. Good luck |
Steve Magnusson (91tr)
Intermediate Member
Username: 91tr
Post Number: 1324
Registered: 1-2001
| | Posted on Thursday, January 16, 2003 - 11:59 am: | |
David N. -- I too would give you a cyber-slap for not using the search function to find this information, but the exact stock offsets on the 16" Cromodora 308QV wheels are:
Front: +11.15 mm
Rear: +11.45 mm
(Barney's 11.5 mm number is obviously close enough, but I wanted to let you know that it's in the "+" direction and not the "-" direction) |
Barney Guzzo (Trinacria)
Junior Member
Username: Trinacria
Post Number: 76
Registered: 8-2002
| | Posted on Thursday, January 16, 2003 - 11:33 am: | |
There is a lot of information about this if you use the search feature on the site. A lot of people are doing wheel work on the 308's. Anyway, your car should be 5x108mm and 11.5mm offset. I think 8.5 inches is the max on the 308 for width. Others might know more than I on the subject. |
David M Nichols (David_nichols)
New member
Username: David_nichols
Post Number: 1
Registered: 1-2003
| | Posted on Thursday, January 16, 2003 - 10:21 am: | |
How wide can I go? Whats the correct offset?
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