Q for 308/328 guys running 10" rears (355 wheels on a pre-ABS 328)

Oooooh! Those wheels look SWEEET!!!

 

Yeah, what model wheels are those? Are those 17's or 18's? What width are you going to run up front?

 

The top will tuck in quite a bit as the suspension settles, so it's not as bad as it looks with the wheel hanging.

The other thing that matters is offset, do you know the offset of that wheel?

My 550 wheels are 10.5" wide with 32mm offset and there is plenty of room on the outside. The problem I had is on the inside, it wants to rud the inner wheel well and the shock, well forget it....I had to move the lower shock mount in 1.62" to clear a 2.5"ID spring.

Going forward I'm seriously thinking about re-working the inner wheel well to allow a wider tire. I currently have 285s, but I'd like to go to about a 315. I know that with a spacer behind the wheel, I could get a little wider, maybe 295 or so, but I'd really like to get 315.......

 

On spacers, i was told from Dan at Ricambi, the minimum is 11mm.

Those wheels you have are 18x10.
My 550's where 18x10.5 and i took out 1" and they fit perfect with the 265/35/18 and no spacers.

You might be better shape then me cause of that .5" but with spacers.

But the wheel might stick out.

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It's been done running an uncut rear wheel, I refuse to have my wheels cut and welded together, I use to design wheels and it's something you don't want to mess around with. I talked to wheel engineers about this last year and they said absolutely no! I know a lot of people have done it but if you see the loads these things go through then you won't do it. I bought a set of 360 wheels for my 308 and I'm going to run the wide stock wheel if I can't make it work which again it's been done then I'll sell the wheels and get something else. Do a search for "lets see 308's" or something like that and you'll see that there is a Red 328 running wide wheels. You can cut the wheel if you want, it's your hide I wouldn't, I've seen to many wheel failures to even think of messing with wheels. Theres a company that I'm talking to that will make up a narrow shock set up if your interested, Pm me for more info.

Jim

 

Those are 355 wheels, right?
Your "frontspace" (I don't know a poper name, it's the opposite of the backspace!) will increase from 1.85 inches to 3.66. Try sticking some 1-3/4" foam on your tires and excercise the suspension. I don't know if something would stick on driving or not, you could always take the shock/spring off & do it in the garage!
For those asking, 355 rear is 10 in wide, 80mm offset. Something you MIGHT be able to do (but I doubt it on a Ferrari factory wheel) is to machine some material off the hub. I had some german aftermarket wheels that had super-thick hubs and we took 5mm off. This was, of course, at my favorite Ferrari hotrod shop, www.weldcraft.com the same guys that people use to narrow their wheels.

 

LOL I dont think you can really get a 315 under the stock fender lip. I have 2.5in springs and theres not alot you can go beyond the fenderwell before hitting something solid (frame) Im running a 12 in wheel with a 6 in offset and just clear the inner fenderwell. and as you can see a 315 still sticks out barely beyond the 1.5in flared fenderlip. Although it would be really cool to get those tucked under
: )
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I moved the shock in 1.62", my 285 actually sits inside the fender a bit more than the stock tire. I'm pretty sure I can get a 305, but you're right a 315 might require a little work on the fender lip.

 

When you say you moved the shock in, was it at both the top & bottom or just the top or bottom. If was at the bottom how much tear up of the lower Arm for shock clearance?

Jim

 

A Heads UP!!!

I just talked to a friend of mine that is a racing suspension engineer about moving the lower shock mounting position 1.6 in. and he said moving the lower shock point will increase the loads dramatically on your suspension upper mount and it has increased your spring rate also. As time goes on you could see the metal fatiguing in that area if you don't reinforce it. Leaving that lower mount location in it's stock position and going to a narrow shock and spring is the way to go. Your upper mount should now be reinforced to coup with the loads your putting on it, probably tying both sides together with a strut bar. My friend worked with many major teams over the years, Grand Am, ALMS, so when he says something I'm all ears. I noticed in your profile that your a mech. engineer so you are probably aware of this and compensated for it.

Jim

 

Here's mine with the stock uncut rear 360 wheel and 285 tire no spacer. Shock is remove for trial fit.
Jim
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Correction in the picture it's a 275-40 ZR18 tire on a 360 wheel no spacer not a 285.

What would be the Dia. of a narrow body shock and spring that would work with an uncut wheel? Anybody have luck with a 2in. dia spring clearing ?

Jim

 

I know that Paul Sloan has uncut 360 wheels on his car, but I don't recall reading what he did. You might try contacting him.

In my case, I knew I would be autocrossing and driving on rough northeast roads, so I had to have all the wheel travel with no rubbing, so I went the move the shock route. The upper A-arm needed a lot of cutting, so I added a new guest on the outside of the shock to get the strength back.

Has you friend taken a good look at the 308 geometry? I ask because I’m honestly having trouble understanding the concern about the upper mount….maybe he was thinking I moved the upper mount in, which would definately weaken it significantly?

Anyway, on the spring rate change, it actually works out very close the stock. Moving the mount in stands the shock up a bit, which effectively increases the rate a bit. But moving the stock in also decreases the travel a bit due to a bit more rotation influence from the longer lever arm on the wheel carrier. Taking the 2 effects together adds up to almost no change in spring rate.

I made this change about 6 years and 15k miles ago I think and it seems to be just fine. The funny thing is that when I has making the change, I noticed…….you guessed it, the upper mounts on both sides were cracked from the OEM set-up. I re-welded everything at that time, and I just went and gave it a good look over and there’s no sign of any new problem.

 

Tillman
What's Paul's user name?
Jim

 

I think it's Sloan83qv....now that I think about it, I haven't seen anything he posted for quite a while....maybe make it an email, not a PM.

Mark

 

What bolts length are you running with your uncut rears? Also what bolt and spacer size are you using in the front?

Jim

 

I made studs, I'll have to measure them....my record keeping skills leave a bit to be desired, I should have been born italian I

f you do a search on 550 wheel, another member just did it and posted everything he used I think.

My front spacers are 25mm. The front wheels are 8.5" wide with 46mm offset. The rears are 10.5" wide with 32mm offset and no spacer.

 

To fit my 18" x 9" rears with a 25mm offset I had to get the arches rolled. That really was the only mod I made. I have about 1cm between the rim and the suspension. I guess I would have been better off with a 30mm offset but couldn't find any data anywhere before I bought them

regards
Nick

 

Thanks for the reply, do your fronts clear the fender lip at 25mm? I found a company that will make me up a set of rear shocks with a 1 5/8 OD and spring 2 5/8 OD this should work.

Jim

 

They do with a 225 tire, bit my 235 slicks rub a bit on hard conders....I'll have to shave the spacers if I want to keep using them I guess.

With such a tiny shock, I'd think a remote reservoir would be in order. That is a tiny spring, mine are about 3.5" OD. I use 12" long 400lb/in rear and 10" x 450 lb/in front.

 

It's Pro-Formance shock

http://www.proshocks.com/index.htm
They do everything from sprint cars to street cars.

Jim