What is total spring "travel" on Q45?

[szh]

Hi, all.

I hope I am asking the right question here and this makes sense!

What is the total travel of the wheel on a 1995 Q45? The reason I ask is that I am experimenting with a wheel and tire combo that is:

1. Using 245/45-17 to get close (but not exact) to stock diameter on the stock 15" rim.

2. Low enough offset (30mm) that the tire just extends out enough to be below the fender. The outer edge of the tire is flush with the outer edge of the fender. This looks great, by the way!

This leaves about 2 to 2.5" of room above the tire to the edge of the metal when the car is resting on level round. I looked at the stock springs on the Q, and it looks like the spacing between the coils is lower than that (somewhere less than 1.5" or so).

Is this situation dangerous? Does the above spring coil measurement imply that the total travel on the wheel is about 2" or so? Will my tires touch the fender on bad bumps?

In driving so far, I cannot tell if it has touched the fender at all on bumps or highway dips, but I am worried that I may be in for a rude awakening! I'd like to get opinions from people on this so that I can decide if I want to keep this combination!

I'll try to take pictures if I can ...

Z

[DAEDALUS]

Q45tech has more knowledge and experience with the Q suspension than anyone else I'm aware of. There is a lot of good info in this thread:

http://www.nissaninfiniticlub....14271

If I read that right, stock travel is 4.25". Verify with the FSM.

[Q45tech]

The suspension has camber gain. That means as the suspension compresses [handling or bumps] the top of the tire moves inward roughly 0.8 degree per inch.The shock absorbers have a total of 7" of movement, but this is reduced to 6" with a rubber bump stop. So the spring/shock combo yields approximately +- 3.0" of range.

The fender curve and inside plastic liner are designed for the 215/65/15 tire but 235/15 and 245/16 even 255/16 are known to work.............no personal experience with 17" or larger.

Tires in the supposed same size may have different SHOULDER ANGLES/SHAPES.

http://www.carbidedepot.com/formulas-tr ... assi2.html

[911/Q45]

255/45-17 on 8" rims with 40mm offset and Eibach springs clear the fender fine and just squeak against the sway bar at full lock. Your tires are about .5" narrower and your offset is about .5" more to the outside, so with the stock ride height you should be just fine. If it does touch, you shouldn't experience catastrophic problems, just a funny noise and a mark on the tire.

[szh]

Thanks for the response, folks! I took a few pictures and will post them shortly ...

Z

[szh]

Here is a picture of the rear side view ... (yes, yes, I know all my dust boots need replacing ... that is in the works, along with the shocks). Images are small because of the silly limitation we have here on picture size.

Z

[szh]

Here is a view from the top (not totally at right angles ... it is kinda tricky to hold the camera just right).

Z

[szh]

Left front side view ...

Z

[szh]

Left front top view ... wheel was not straight when I parked, so it is a bit misleading.

Z

[szh]

Here is the full rear wheel view ... it does not do the car justice. I will post complete pictures later. The car looks stunning with these wheels on them!

Z

[elwesso]

I want your rims!!!!

[Q451990]

I'd think a good test would be some chalk on the spots that you think will hit and a spirited drive over some railroad tracks...

Heath

[AZhitman]

My 255/50/16's don't touch anywhere, even with the 1" drop contributed by the Eibach's (actually a 1.1" drop on all four corners from the specs listed in the FSM).

[szh]

I want your rims!!!!

They do look good, don't they?

I will try to have some fuller pictures soon ...

Z

[szh]

I'd think a good test would be some chalk on the spots that you think will hit and a spirited drive over some railroad tracks...

Heath

Hmmm. Good suggestion. I will try it. Although I think that dips in the highway are the concerns I really have: tire rubbing at high speeds!

[szh]

My 255/50/16's don't touch anywhere, even with the 1" drop contributed by the Eibach's (actually a 1.1" drop on all four corners from the specs listed in the FSM).

Does the tire extend out under the edge of the fender? Sorta like the pictures I show? If so, I am surprised it does not touch on hard bumps! Good to know!

What are the offsets on your rims?

Z

[AZhitman]

Factory 99Q rims (offset unknown).

The tires do not extend beyond fenderwell, and even during aggressive driving, the bumpstops would limit any tire to fender contact. Also, remember what Dennis said: The suspension has camber gain. That means as the suspension compresses [handling or bumps] the top of the tire moves inward roughly 0.8 degree per inch.

Even if you were close, they'd "tuck" at full compression.

[sijoko]

As long as your vehicle is at the stock ride height and your bump stops are in good condition, there should not be any rubbing.

If you really want to be sure, you would have to disconnect the strut and push the wheel/tire combo upward with a jack. If the tire clears the fender arch, then you should be good to go.

If you have already driven on some rough roads and there isn't any rubbing then you are alright. Even if the tires did rub, it would not be catastrophic.

-sijoko

[Rex]

I have rims of unknown offset (they were on the car when I bought it) and they're wrapped in 245/45/17's and I have had NO issues with rubbing. I posted a pic of the rim before to see if anyone could recognize them, with no luck.

Not sure if the Eibach's will create a problem.

[szh]

Factory 99Q rims (offset unknown).

If you happen to have your wheels off at some point in the future for rebalancing, you might look on the inside of the spokes and see what it is. It should be stamped (raised into the metal actually) on the inside - somewhere near the wheel dimension info. My guess is 35mm or 40mm - let's see if I am right! Quote » The tires do not extend beyond fenderwell, and even during aggressive driving, the bumpstops would limit any tire to fender contact. Also, remember what Dennis said: The suspension has camber gain. That means as the suspension compresses [handling or bumps] the top of the tire moves inward roughly 0.8 degree per inch.

Even if you were close, they'd "tuck" at full compression. [/quote]

Yup! I understand the "tipping in" of the top of the wheel, but do not understand the "0.8 degree per inch" measure. Per inch of what? The wheel rim size? The total wheel diameter? Something else?

I assume the 0.8 degree refers to the camber change, but what is the length of the moment arm to which it applies? This would allow me to calculate the actual "tilt" of the wheel, I think!

Z

[sultan]

can't help you with that, but don't worry about rubbing the fender on the rear, i had 27" diameter (1 inch taller) tires and eibach springs, didn't rub AND my tires extend past the fender. don't know about the front.

i'm working on getting some 16x8 nissan wheels, but not 300ZX because i don't like the looks.

[Q45tech]

When the wheel moves up or down from it's normal static postion [bumps or rebounds] the camber changes 0.8 degree per inch of travel. So the outer edge of tire top moves inward. Now its not much movement less than 0.35" in total for full compresssion.This is what the angled upper link does....... creates.

[szh]

Hi, Dennis.

[quote=" Q45tech When the wheel moves up or down from it's normal static postion [bumps or rebounds] the camber changes 0.8 degree per inch of travel. So the outer edge of tire top moves inward. Now its not much movement less than 0.35" in total for full compresssion.This is what the angled upper link does....... creates. [/quote]

Great! That number is exactly what I was looking for - I was trying to calculate the movement inward. Thanks for the info. It looks like the tire I am using now might just barely touch - perhaps only slightly - based on my rough measurements when it has "traveled" about 2.5" to 3.0" or so.

On the other hand, one with a smaller tread width will probably clear the fender pretty easily. So-o-o-o ... my next tire will be the SZ50EP (again) for a number of reasons!

Thanks much, Dennis!

Z