Reverse mount LMs, a quick Q

[.Mad Hatter.]

question for you guys re: LMs.

For those who have reverse mounted, did you machine the mounting surface of the face in order to ensure it was flat and true prior to reverse mounting? If not, do you notice any negatives?

Wheels in question are 18x8/9 5x114 if it makes a difference. I see a lot of people doing this and I have to assume most don't take the time to machine the face. Some of the Porsche guys have commented on it but I see mixed opinions. "Apparently" the 18" LMs can be reverse mounted without machining...but I don't ever see any info backing that up.

TIA

[Zic]

If you look at the center were the bolts go in, you can see if they sit in a recces like in the picture below.

and secondly look if the edge is angled or straight.

the first part is not so important about the recces, but if the edge is angled you might run into issues with mounting the faces securely also with balancing the wheel it self. If i was you i would just machine the edge flat and removing the recces for the bolts in the process.

[Jesus Christ]

ive heard of people getting away with just reverse mounting them but if it were my wheels id have edge of the wheel machined to be flat.

[.Mad Hatter.]

The recess I'm not super concerned about. I will try measuring the mounting surface with a caliper but it may or may not give a true answer on whether it is really flat. Thanks for the insight! Hopefully someone who has done it without machining can weigh in.

[StatusRacing]

The recess I'm not super concerned about. I will try measuring the mounting surface with a caliper but it may or may not give a true answer on whether it is really flat. Thanks for the insight! Hopefully someone who has done it without machining can weigh in.

I wonder if measuring runout would be possible.

[.Mad Hatter.]

That might work; it would help determine if there was a "wave" in the face. I don't know if it would let you know if the face thickness is the same on the edge as it is toward the inner lip of the mounting surface. I am reverse mounting a buddies set this Saturday so I will take some measurements and report back. Hopefully the caliper can assist a bit.

[yotatuner]

I didnt machine my 17x9" just make sure there centered right!!! I bought like 3 packs of razors and used them as spacers in a star pattern so I could have the same gap all the way around.

[.Mad Hatter.]

Do you mean around the center ring? I plan to hand thread the bolts loosely to ensure that nothing gets cross threaded.

[.Mad Hatter.]

Ok, so we got the rears done today, the face is flat at the mounting surface based on what we discovered. We went ahead and worked on the lips, and re-torqued the bolts to 20ft lbs. (used bolts)

[iwannabeam3]

those are reverse mounted?

[yotatuner]

^ yes those are reverse mounted

[audiwark]

I didn't do any machining on mine:

[.Mad Hatter.]

Bringing this back up because I am going to re-finish my LMs this winter. Anybody have horror stories with a reverse mounted set? All the pressure of the weight of the car is on the bolts instead of the actual face/barrel. That is my only concern.

Wheels in question:

[livinzlyfe]

Bringing this back up because I am going to re-finish my LMs this winter. Anybody have horror stories with a reverse mounted set? All the pressure of the weight of the car is on the bolts instead of the actual face/barrel. That is my only concern.

no it isn't. LM faces have a lip on both front and rear. so, the weight distribution will be the same before and after reverse mounting them. Although, I recommend having the wheels rebalanced after pulling the faces out. I pulled 2 of mine out 2 weeks ago to change the position of them, and after putting them back in, my steering wheel vibrated. and I remember the face having some play when I was bolting it back in.

[Undftd:Fiji]

i assume that all, if not, most LM faces have flat edges? since it seems like a couple of you just reverse mounted by hand without machining them.
i might buy a used set soon and reverse mount myself so I'll need to double check that.