400i Wheel fitment question...

My 1983 400i wheels are negative 5mm offset (100mm backspace and 110mm frontspace). the 308 and Mondial are positive offset. So for the wheels you have (and why are they different front and rear?), you'd ideally be looking at 36mm spacers up front and 29mm in back. As I can tell, all 70's and newer Ferraris have the same wheel hub spacing (108mm lug spacing with a 67mm hub). So if you have a Ferrari wheel, it will bolt up to any other hub--the offset and the lug length are the things to get right.
I've been working at fitting 348 wheels on the 400i, but will likely give up and use 16" 308 wheels....the issue I cannot solve (at least, to use the 9" rears) is that the US style rears need a very long (80mm) lug...too long for the wheel spacer needed....Lee

 

Ferrari 348 fronts should be pretty easy to fit up; the rears are trickier. It may be a smart thing to simply use the fronts all around--after all, 348 fronts are wider than the original TRX (7.5" vs ~7.3"/185mm), so there should be no sacrifice in handling. A 7.5" wheel is still OK for a 245/45/17 wide tire.

- to make the 348 fronts work simply needs a 2" spacer, with studs that extend 50mm proud of the wheel face. The 348 fronts have a positive 49mm offset, so with 50mm spacers the front track will 4mm narrower per wheel (since the TRX is a negative 5mm offset). To my thinking, 4mm error on a 245 wide tire should be a tie...

- 348 rear wheels come in 2 different flavors. Both are 9" wide, the difference is the width of the wheel and the lug used.
a. earlier 348s have a 68mm offset and use a 50-55mm lug bolt. These are part numbers 136547 (right) and 136538 (left). To fit these would need a 3" spacer and studs that are 50mm proud of the hub.
b. later 348s (all US models after 93, I think) practically cannot be used with stud-type spacers...The offset for these (#156244/156242) is decreased to only 43mm--but the width of the wheel is increased 25mm to match, and uses an incredibly long (80mm) bolt. The spacer would need to have studs that are 75-80mm proud of the face. The problem is that this length of stud is not to be found (since the stud is pressed into the spacer, the stud would have to actually be about 90mm true length to provide 75mm stud length proud of the hub face).

H&R, at least, makes thinner spacers (up to 30mm) that use the ferrari lug and put threads into the spacers. I don't know if they are actually threading into aluminum (!) or more likely have steel inserts. If you could get a 2" spacer with inserts, then a set of 10 long bolts (the 80mm 348 rears that go with the 156242/156244 wheels) is only 90 sterling/us$150 from Hill Engineering.

So finally, I think a very practical recipe is just to go with the 348 7.5" (fronts) all around and use 2" spacers. 348 wheels are still a bargain, the car still looks like a Ferrari and they are very high quality wheels. Lug bolts to fix the spacer to the hub (14mmx1.5mm conical lug bolts) are easy and cheap to find, and lug nuts are same as used on some Chevy trucks (for chrome acorns) or you can use Porsche alloy nuts. Keeping the same wheel/tire front and rear also solves the problem having the right spare...Lee

 

Btw, good news on a couple of fronts;
- fitting the 308 wheels (or repros) is quite easy--just add 15mm spacers. Incredibly, you can still use the 400 wheel bolts (as the 308 wheel hub thickness is coincidentally thinner than the 400 wheel by 15mm ! So both offset and wheel bolts are solved simply with the spacer. Spacers can be found for as little as $25 each, even for forged. Sorry about my previous entry, you will need a 58.0mm (or greater) hub diameter on the spacer (not 67mm).

- Also good news for fitting 348 rear wheels; longer wheel studs are available after all (to fit even the later 348 spyder wheels with a 2" spacer). Specifically, Dorman 610-333 studs are 90mm long--so can be fit into a 2" spacer and protrude the ~75mm needed for the later 348 rears. These are the same studs fit on Chevy trucks, so you'd think could handle all the Ferrari torque.


---Lee

 

there has been a very detailed discussion on this subject, search function time

 

Thanks for the details, very useful to have. Can you post some photos of your car? I bet there aren't many 400s in Taiwan!

Aidan

 

These are the spacers I'm using on my 400.
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Hi markcF355,

Do those spacers not overstress your bearings, suspension joints etc?

Niall

 

No. The rims I mounted have a large positive offset so these spacers 'convert' them into the same negative offset as the stock rims.

So, the bearings 'see' the same rim as if stock.