Hyundai Genesis Forum banner

1 - 20 of 23 Posts

·
Been there, but forgot it
Joined
·
161 Posts
Discussion Starter #1
Got my R-Spec last week, 5' 4" wife felt she was sitting in a hole. I searched here and found a thread that said you could not change the seat mounting.
Being stubborn I did it anyhow. Bought 2 longer bolts (careful they are 1.25 fine threads, not 1.50 as most hardware stores sell) and two 1/2 collars as spacers. Didn't change the front, just added these to the back. Worked great.

 

·
n00b
Joined
·
283 Posts
My 5'3" wife is the same, but she's used to it lol.
 

·
Registered
Joined
·
3,093 Posts
my wife is 5' 2"....


I just tell her she can either sit on a pillow... or sit on something else............

...............
...........
......
...
..
.
 

·
Premium Member
Joined
·
13 Posts
Bought 2 longer bolts (careful they are 1.25 fine threads, not 1.50 as most hardware stores sell) and two 1/2 collars as spacers.
Boy, I would be reluctant to do this. Bolts come in different strength grades, and unless you went out of your way to find the proper grade, hardware store bolts aren't as strong as the ones the car came with. This means that in the event of a crash (particularly side impact), you may have compromised that essential link in a safety system.

The minimum tensile strength of the stock bolt is probably 150ksi (for a Grade 8 bolt). The typical hardware store bolt may only be 60ksi strength. I wouldn't want to find out what happens to a seat mounted with bolts only 40% as strong as they are supposed to be.

Additionally, changing the mounting geometry will probably increase the load on the bolt, due to the longer moment arm you've created with the longer bolt.

I can appreciate the complaint of an uncomfortable passenger, but personally I wouldn't go this route. There's too much engineering that goes into crash safety, and too much at stake if you re-engineer something wrong. Plus, if your automobile insurer ever were to find out you've modified a safety component (such as investigating a wrecked car) you may also invalidate some insurance coverage.

I don't mean to just be a downer, but please be sure to think about stuff like this when modifying the structure.
 

·
Registered
Joined
·
3,093 Posts
That's gonna be a short trip......
yeah, the pillow will raise her about 3-4 inches.... knowing how grim I feel after looking in the mirror every morning, I guess id raise her the same.
BAAHAHAHAAHAHHAHAHA
 

·
Registered
Joined
·
29 Posts
Mines 5'1 , never complained .... Her car is lowered though :grin: Probably has something to do with it ....
 

·
Registered
Joined
·
11 Posts
I drove a 83 Chevette for 4 years and the seats were really low since they were custom and let me tell you it literally felt like your ass was on the ground. Shell get over it.
 

·
I'd rather do it myself
Joined
·
18,275 Posts
Boy, I would be reluctant to do this. Bolts come in different strength grades, and unless you went out of your way to find the proper grade, hardware store bolts aren't as strong as the ones the car came with. This means that in the event of a crash (particularly side impact), you may have compromised that essential link in a safety system.

The minimum tensile strength of the stock bolt is probably 150ksi (for a Grade 8 bolt). The typical hardware store bolt may only be 60ksi strength. I wouldn't want to find out what happens to a seat mounted with bolts only 40% as strong as they are supposed to be.

Additionally, changing the mounting geometry will probably increase the load on the bolt, due to the longer moment arm you've created with the longer bolt.

I can appreciate the complaint of an uncomfortable passenger, but personally I wouldn't go this route. There's too much engineering that goes into crash safety, and too much at stake if you re-engineer something wrong. Plus, if your automobile insurer ever were to find out you've modified a safety component (such as investigating a wrecked car) you may also invalidate some insurance coverage.

I don't mean to just be a downer, but please be sure to think about stuff like this when modifying the structure.
Approximate metric equivalent to a grade 8 SAE bolt would be a 10.9. There is also a harder bolt, 12.9.


Grade 8 = 120 psi
M10.9 = 830 kilopascal

120 psi = 827 kilopascal


Steel Bolts - Metric Grades

http://www.engineeringtoolbox.com/steel-bolts-sae-grades-d_1426.html]Steel Bolts - SAE Grades
 

·
Registered
Joined
·
432 Posts
I just tell people to get used to it; its a sports car, its low, that's the point. Hahaha. Girlfriend is 5'2" and loves the car tho, as does most everyone that sits up front, especially smaller women funny enough, hahaha. Now anyone who's had to sit in the back, that's a whole different story.... xD
 

·
Premium Member
Joined
·
13 Posts
Approximate metric equivalent to a grade 8 SAE bolt would be a 10.9. There is also a harder bolt, 12.9.

Grade 8 = 120 ksi
M10.9 = 830 megapascal

120 ksi = 827 megapascal
Fixed those units for you there :wink:

I had suggested a SAE grade 8 as an example for high strength properties. Of course you're right that it would be a metric bolt. I think the tensile strength is more relevant than the proof strength in this case, because the behavior beyond yield isn't necessarily parallel between grades, and the major issue depends on exceeding the tensile strength, not the yield strength. But either measure should show the relative weakness of an ordinary bolt.

Checking my car, the actual bolt is a metric Class 8 (which of course has a different strength from an SAE Grade 8). Using Red Raspberry's links, a metric Class 8 bolt has ultimate tensile strength of 120 ksi (830 MPa). For an unmarked bolt, the minimum tensile strength is 58ksi (400 MPa), so it will have only 48% of the tensile strength as the OEM bolt. (Using proof strength gets an even worse ratio, 87ksi for Class 8, 33ksi for an unmarked bolt, only 38% of the proof strength).

You're definitely compromising the safety performance of your seat if you use ordinary bolts to replace these high strength bolts. Even if you used Class 8 bolts or higher, I still wouldn't want to get into guessing the ramifications of using a collar and a longer bolt vs. clamping the bracket directly to the floor.

I think the safest option is to get a taller wife. :grin:
 

·
Registered
Joined
·
3,093 Posts
I just tell people to get used to it; its a sports car, its low, that's the point. Hahaha. Girlfriend is 5'2" and loves the car tho, as does most everyone that sits up front, especially smaller women funny enough, hahaha. Now anyone who's had to sit in the back, that's a whole different story.... xD
You better watch it brah! Don't let your woman see this post!!:wink:
 

·
Registered
Joined
·
3,093 Posts
HAHAHA, I didn't even mean it like that, that's hilarious!
Im just saying.... that's an "open Mouth, Insert foot" moment right there!! hahahaha
 

·
Registered
Joined
·
27 Posts
Rather than using the collar shown in KurtFredrick's photo, it would seem safer to use a 2-1/4" diameter solid metal cylindrical spacer (ideally 1.5" tall) and only do this on the rear two seat rail bolt holes. This would raise the seat 1.5 inches at the rear, and the seat occupant could then adjust the seat back recline lever as needed to be comfortable. You would then only need two new, longer bolts - specifically, two bolts of equal or higher tensile strength than the stock number 8 metric bolts. The two new bolts would need to be 2-5/8" long (from base of bolt head to tip of bolt). Using a wide, solid round spacer would ensure that the rounded rear seat rail mounting bracket would be fully supported on all sides by the spacer and sandwiched securely by the new bolt. The collar shown in the photo provides no lateral support and could be hazardous for that reason.

Modifying the front seat mountings is probably not necessary - (it's your butts that need a lift!) , and besides, it's trickier, because they not only use a threaded mounting bolt, but also an unthreaded locating rivet. You can't (and shouldn't) get the locating rivet out of the seat mount, and with a spacer, it's not long enough to reach into its locating hole anymore. So you would lose the extra strength of the locating rivet if you simply added a spacer under the front bolt. You have to assume that the rivet is there for a definite purpose, so defeating its purpose would probably not be wise.

I tested the rear-mount-only approach on my 2016 3.8 Gen Coupe by temporarily placing two 1.5 inch tall wooden blocks under the rear seat mounts (without bolts; just to hold the rear of the seat in a raised position so I could try out how this affected the seat's comfort.) Not only did the seat come up to a great new height, but the new position also took some of the angle off the bottom of the seat, which helps me because the stock seat design , with its angled front lip, puts too much pressure under my lower thighs. Raising only the rear mounts by 1.5" takes that pressure off, gets me to the right height, and makes the seat much more comfortable.

Doing this to the driver's seat means you also still have the driver's seat height adjuster to fine-tune the seat height....only difference is that now you don't have to have it always cranked all the way up to the highest setting anymore...you can actually use it to fine-tune your seat position! Doing this to the passenger seat will also make the passenger equally happier/higher, even though they don't have a height adjusting lever on that side. Hope this helps!
 

·
Registered
Joined
·
27 Posts
Well, I went to a metal shop and had them cut me four 1.25 inch long, 2" diameter hardened aircraft aluminum rod spacers. (I re-thought the height issue and determined 1.25 inches would be the best height for me.)Then I marked the centers of each spacer and took the spacers to a machine shop and had them bore bolt holes through the centers of each spacer. I put the spacers under the driver and passenger seat REAR mounts only, using four new, longer, high strength bolts acquired from Fastenal. The result is just perfect, at least for me and The Boss. Attached is a photo showng how they look. Total cost was about $55 but you could do it a lot cheaper if you cut your own spacers and bored your own holes. These spacers, being wider than small piece of tubing used by the originator of this thread, seem to me to give better, more appropriate support to the rounded rear seat brackets, hopefully for a greater margin of safety. Hope this helps...

 

·
Registered
Joined
·
27 Posts
I've tried six aftermarket seat pads, and I haven't found ANY that fit the seat and are comfortable. And, the manual warns against seat pads because they can allow your hips to slide forward in a crash, increasing potential for injury.

So I invented the above-mentioned spacers out of solid aluminum rod stock. But the problem with installing spacers under the seats on a GenCoupe is that the floor where the threaded mounting bolt holes are located, is not flat, so the bolts are not perpendicular to each other. If you use spacers to raise the seat rails, the bolt holes in the seat rails no longer line up with the threaded bolt holes, due to their offset geometry. If you decide to just put a spacer under the rear mounts, when you tighten the rear bolts to the floor through the spacers, the front seat mounting bracket will tend to 'float' in mid-air above its threaded floor holes. You can force a seat bolt into those front threads, but as you tighten it to the floor, you are literally bending the seat down at the front, bowing the seat mount rails, which could cause problems with forward/backward seat adjustment.

If you try to put a spacer under both the rear and front mounts using longer bolts, you have more problems because since the spacers are not perpendicular to each other, none of the holes in the rails line up with the threaded bolt holes. By a good deal of hassling, you can get all four bolts started, but as you tighten them down, the bolts will progressively bind in the threads.

I did manage to install spacers front and rear this way for both the driver's seat and passenger seat, but then as fate would have it, a couple of weeks later, I received the infamous GenCoupe passenger seat airbag wiring recall, which entails the dealer removing the passenger seat, re-routing its underseat cable, and better securing the passenger seat's male/female cable plugs to each other. Since the dealer would have to remove the seat for this fix, I felt it prudent to remove all the passenger seat spacers and reinstall the factory bolts, to avoid any potential hassles.

But when I reinstalled the factory bolts, I discovered that one of the front holes had become cross-threaded from the prior spacer installation. I was able to clean up the threads with a tapping die, but now that the dealer has performed the fix, I have decided not to disturb the passenger seat mounts again - I'm leaving them alone on the passenger side. For the time being, they're still installed on the driver's side, because I like the higher seat position very much, but I am not sure whether I will leave them installed, or remove them in the future.

It seems to me that the ONLY way to properly raise the seat height by an inch or more on a GenCoupe would be if someone had a very friendly machine shop that could fabricate two special seat raising adapter rails out of hardened steel (or aircraft aluminum) billets, that would (a) exactly fit the shape of the floor, (b) bolt to the floor using the factory threaded floor bolt holes, and (c) have new threaded holes tapped into the adapters at just the right angles allowing you to bolt the seat rails to the adapters without bending the rails. But most machine shops would charge a fortune for this - it’s just not practical.

Here are some drawings that summarize the problem:


 
1 - 20 of 23 Posts
Top