Eibach drop math!

[mcheddadi]

Ok I did some measurements, to see if my coupe could be lowered with my new 19"s. and this is what I found, there is 10mm of horizontal space and 55mm of vertical space between the tire and the fender well tip. Assuming you get same tire proportions as stock...

I came to the conclusion that if you have have ...

MORE than 5mm in horizontal dimension over stock you are going to have to ROLL your wheel well if you decide to drop since you'll only have (55mm - 38mm's eibach drop =17mm) 17mm left of horizontal space left between your tire and the fender well tip!! Bumps will make you RUB! Unless the springs are so stiff that there is less than 17mm of wheel travel with bumps..

So, still assuming you get same tire proportions as stock:

+45 offset and 225 wide tires you shouldn't rub horizontally with the fender tip edge (5mm left) but to be sure go with < or = to 215 (215, 205, 195 ...) and you WON'T rub horizontally . If more than 225 with +45 you will HAVE TO ROLL TO DROP...

+40 offset and 215 tires you shouldn't rub horizontally with the fender tip edge (5mm left) but to be sure go with < or = to 205 and you WON'T rub horizontally . If more than 215 with +40 you will HAVE TO ROLL TO DROP...

anything less than +40 is asking for it (still assuming you get same tire proportions as stock...). you'll have to get either very narrow tires or ROLL YOUR WHEEL WELL.

+35 offset and you'll have to get narrower than stock 17" wheels, 205 tires you shouldn't rub horizontally with the fender tip edge (5mm left) but to be sure go with < or = to 195 and you WON'T rub horizontally .

anything less than +35 is IMPOSSIBLE TO DROP without RUBBING. YOU'LL HAVE TO ROLL TO DROP (again, assuming you get same tire proportions as stock...!)

but if you go with less than stock proportions then you might have more than only 17mm of vertical space if you do get tires bigger than the 10mm horizontal limit...

and if you go for bigger than stock proportions, YOU'LL HAVE EVEN LESS THAN 17mm of vertical space if you do get tires bigger than the 10mm horizontal limit...

that's it I think...correct me if I'm wrong guys!

oh yeah, again, all of this is only if you decide to DROP.

[kidatheart]

That is good information. Just to make sure I am thinking correctly here for my situation I am considering 18" wheels that are 18 x 8.5 w/ +35 offset and putting 245/45/18 tires. Based on what I think I understand your description to read I will not be able to do a drop without rolling the wheel well??? At least not with the Eibach. I am guessing that if I hold out for the Tanabe coilovers I would be OK.

[mcheddadi]

That is good information. Just to make sure I am thinking correctly here for my situation I am considering 18" wheels that are 18 x 8.5 w/ +35 offset and putting 245/45/18 tires. Based on what I think I understand your description to read I will not be able to do a drop without rolling the wheel well??? At least not with the Eibach. I am guessing that if I hold out for the Tanabe coilovers I would be OK.

245/45/18 is 1.4% bigger than stock proportions so you'll have 10mm (0.5") more for the diameter. if you drop with eibach you have...7mm of clearance bettween the fender tip and your wheel

[IMrGoodBarI]

so if I am understanding this with my rims 19x8 with 40 mm offset with a tire of 245/35/19 I would rub

[generic808]

If you look at the way a suspension articulates and compresses, you'll see that in theory, it all seems good, but in actuality, things are sometimes different. There are many factors to take into consideration, especially camber, caster and toe. If you notice when your suspension compresses, it tucks inward toward the top? So sometimes the measurements you listed won't apply.

This post is great, and it's good to see that you put all the info together; however, real world applications sometimes don't apply to the measurements. It's a good guideline though. You never really know if you're going to rub until you actually have your set-up going. Of course, there's always the fail-safe +45 offset of the factory wheels.

[rjdmmfl1]

245/45/18 is 1.4% bigger than stock proportions so you'll have 10mm (0.5") more for the diameter. if you drop with eibach you have...7mm of clearance bettween the fender tip and your wheel

ok, I haven't done the math, and I'm not sure how you came up with these numbers, but i'm not sure its as simple as the above diagram. Eric has 225 tires on his 18 x 8" wheels with +45 offset, and he had to use +7mm spacers to get his wheels flush with the fender. So, with that being said, his 225 wide tires on a 8" wheels would have fit just the same if his offset was +38 instead of +45 with spacers...

Bottom line is, we could all do as many rough numbers estimates as possible, but none of us can make any real claims as to what will or will not rub until we put the Eibachs on, and fins out exactly how stiff the suspension is with the Eibachs.

Because of the way Eibach does its R&D, I believe they keep the same spring rate as the factory, just in a 1" lower spring. In any case, we will all see next month when we all install our springs, and post on here what does and does not rub with various offsets, wheel widths, tire diameters

[mcheddadi]

so if I am understanding this with my rims 19x8 with 40 mm offset with a tire of 245/35/19 I would rub

Your wheel proportions are 2.1% less than stock so you have 14mm less in diameter than stock. with 245 and 40+ offset you are going to be 20mm farther than stock, so the 10mm theoretical limit is breached. So since you have 14mm less than stock your going to have 17mm + 14mm = 31mm (1.22inch) of vertical space from tire to fender tip. you might now rub if the suspention is stiff enough to limit the wheel travel to those 31mm.

If you look at the way a suspension articulates and compresses, you'll see that in theory, it all seems good, but in actuality, things are sometimes different. There are many factors to take into consideration, especially camber, caster and toe. If you notice when your suspension compresses, it tucks inward toward the top? So sometimes the measurements you listed won't apply.

This post is great, and it's good to see that you put all the info together; however, real world applications sometimes don't apply to the measurements. It's a good guideline though. You never really know if you're going to rub until you actually have your set-up going. Of course, there's always the fail-safe +45 offset of the factory wheels.

I really hopes it does tucks inward a LOT toward the top. I guess we will know for sure soon enough with the eibach group buy

[mcheddadi]

ok, I haven't done the math, and I'm not sure how you came up with these numbers, but i'm not sure its as simple as the above diagram. Eric has 225 tires on his 18 x 8" wheels with +45 offset, and he had to use +7mm spacers to get his wheels flush with the fender. So, with that being said, his 225 wide tires on a 8" wheels would have fit just the same if his offset was +38 instead of +45 with spacers...

Bottom line is, we could all do as many rough numbers estimates as possible, but none of us can make any real claims as to what will or will not rub until we put the Eibachs on, and fins out exactly how stiff the suspension is with the Eibachs.

Because of the way Eibach does its R&D, I believe they keep the same spring rate as the factory, just in a 1" lower spring. In any case, we will all see next month when we all install our springs, and post on here what does and does not rub with various offsets, wheel widths, tire diameters

[Shift_Altima]

Hi. What does 'rolling the wheel' mean?

[generic808]

"Rolling the fender" is a technique used to pull the fender outward to allow for wider wheels/lower offset. Old school ways of doing this is with a wooden baseball bat placed between the tire and fender. You slowly drive your car foward, allowing the bat to "roll" the metal fender outward. There are better techniques used these days, but the BB bat method still works well if you know what you're doing. I used that technique on my old S13 and it came out pretty nice and even.

[adidas2go]

So i was doing a canyon run in Malibu. Wore a hole in the fender guard plastic. I would be afraid of upgrading past 18's if you plan on doing some autocrossing or anything...

[SHIFT_COUPE]

Blake man, that doesn't look too good. Take some shots with the wheel turned in when you get a chance. I'd like to see how far from the wheel well it is.

[generic808]

At least you can now access your lights without removing the wheel

[adidas2go]

Blake man, that doesn't look too good. Take some shots with the wheel turned in when you get a chance. I'd like to see how far from the wheel well it is.

[Loop]

Is that because of your new drop? or did something hit it.

Now I wonder if I should do the Tanabe springs. Because those were suppost to be a 1.5- 2 in. drop with a higher spring rate. Interesting, thanks for posting that info.

[rj alty 07]

A canyon run? Did something fly up and cut through or was that from rubbing? Thanks for posting it.. btw. That is some crazy rubbing

[generic808]

That's definitely rubbage. I'm pretty sure he was digging hard into turns, thus creating the major tire rub. That wouldn't happen from normal driving though.

[adidas2go]

Canyon Run is a section of a windy canyon road where they hold races to see who can get the fastest time from one end to the other. In my case This was in the Santa Monica Mnts in Malibu. Anyways, this wasn't anything I hit. There is a section of the road that is a 3/4 mile 10 degree right bank turn. I started the turn at 90 mph and ended at 110. I imagine during this time, since i was making a right turn all the weight was shifted to the front left of the car, The tire was turned at just the right angle with just enough shifted wieght to cause the tire to rub.

[LongBeachCoupe]

MChdeaddddi lol... So your mystical math says that i will have an issue? 20x8.5 245/35/20 +38

[mcheddadi]

MChdeaddddi lol... So your mystical math says that i will have an issue? 20x8.5 245/35/20 +38

you got 0.5 inch more diameter than stock, and you are 22mm farther than stock...so with a drop if you don't rub anyone can buy springs lool!

[johnny_d]

Blake,

I noticed the bottom part of the fender guard was loose, was it like that before or after the rub?

[mazda2005]

MCH I have a quick question, I was on this site that lets you compare the current tire versus what i want to upgrade too and the it said that 18X8.0 with a 40+ offset with 225/45R18 is smaller then the stock setup. Do you think i have more then enough clearance. I dont plan on taking sharp rights at 90-110 mp

[adidas2go]

Blake,

I noticed the bottom part of the fender guard was loose, was it like that before or after the rub?

Its not loose. Its just the way it sits after the Stillen upgrade. Its connected at all points

[mcheddadi]

with +40, you only have 5mm left and with 225 tires you have 5mm for each side more than stock, so you have 0mm left, BUT that's only theoretically and 225 takes 225mm ONLY when FULLY inflated, it's like it's MAXIMUM wideness I think (or maybe it's the wideness when inflated at default psi...I'm not sure) ...and also when your suspension compresses, it tucks inward toward the top like generic808 said. So I'd say you have a very GOOD chance of being able to drop without any rubbing.

GO FOR IT!

and there's always fender rolling if there is some rubbing

[dangeris]

"Rolling the fender" is a technique used to pull the fender outward to allow for wider wheels/lower offset. Old school ways of doing this is with a wooden baseball bat placed between the tire and fender. You slowly drive your car foward, allowing the bat to "roll" the metal fender outward. There are better techniques used these days, but the BB bat method still works well if you know what you're doing. I used that technique on my old S13 and it came out pretty nice and even.

Eric,...would that be with a wooden of Aluminum bat? If one does decides to "roll" their fenders, when you start the actual rolling, wouldn't that effectively make the flat part of our fenders slanted thus pulling the fenders outward? Just curious of how that would look.

Would some one out there please do that to their fenders and post up the results as well as a "How to"?...

[mcheddadi]

"So simple, even a 4 year old can do it!"

http://www.youtube.com/watch?v=IbAnowJtd3o

watch out for the boobs!

[dangeris]

Awesome tool man! I doesn't look like that it pushes the whole fender outward. Wish someone here actually did it and posted up some pics so we can see how it would look.

[generic808]

Eric,...would that be with a wooden of Aluminum bat? If one does decides to "roll" their fenders, when you start the actual rolling, wouldn't that effectively make the flat part of our fenders slanted thus pulling the fenders outward? Just curious of how that would look.

Would some one out there please do that to their fenders and post up the results as well as a "How to"?...

Oh...wooden of course. You don't want to take metal to metal. I did it the old school way back in the day. The Eastwood tool is the best method, IF you can get a hold of one.

[dangeris]

Oh...wooden of course. You don't want to take metal to metal. I did it the old school way back in the day. The Eastwood tool is the best method, IF you can get a hold of one.

Well I found a couple of places that sells them out right for only $250.00 or you can rent them. Since my car is in the shop, I'm thinking of calling them and seeing how much they would charge to roll the fenders.

The Eastwood tool looks very easy to use that even a 4 yr old can operate it; that s is according to the video. I just might rent that darn thing and see what I can do with it.

[Altimus_Maximus]

Rolling the fender isn't going to do anything to stop a rub in that plastic guard piece. Correct me if I'm wrong but that's going to remain in exactly the same position after rolling a fender.

Also, if you look at the rear fender (not sure about the front), you'll see that the panel is a very rigid two-wall construction. That is, the panel is reinforced by another panel behind it all fused together. There is nothing to roll.

Maybe I don't understand the rolling process, but I can't see how it would be possible to deform, fold, or even cut that rear panel.