OEM Final Drive swap

[Toddasaurus]

So, I've been doing some research on swapping out the final drive on my G70. I found a potential candidate... The G80 Sport comes with a 3.909 final drive, whereas our G70 uses a 3.538 ratio.

Genesis Newsroom

The G80 Sport uses the same transmission, engine, and transfer case as our G70's. (3.3 Lambda II)

While looking up the P/N's, I found Hyundai even lets you buy just the ring and pinion gears.
G80 P/N's (front): 47430-4J030 (back): 53030-4J025

They're not super expensive either ($300-$400 each, depending on which online retailer you choose).

But, combing over the service manual, it looks like you have to drop the front subframe just to remove the front differential case!! The rear diff, on the other hand, looks pretty easy to remove. Considering this, I am quickly losing interest in this change. On top of the difficulty of removing the subframe, I still don't know if the G80's ring and pinion gears will even fit on our differentials (most likely front would, but rear is uncertain).

Oh well. Just wanted to share my thoughts. :c

 

[EdP]

So, I've been doing some research on swapping out the final drive on my G70. I found a potential candidate... The G80 Sport comes with a 3.909 final drive, whereas our G70 uses a 3.538 ratio.

I never hear of changing gears any more. Used to be fairly common. How much difference do you think there would be in performance?

Will it void the warranty? The engine will have more rpm per mile if it was even noticed.

 

[Toddasaurus]

I never hear of changing gears any more. Used to be fairly common. How much difference do you think there would be in performance?

Will it void the warranty? The engine will have more rpm per mile if it was even noticed.

It's a good question. The difference in performance wouldn't be huge, but it would be noticeable. 0-60 times would certainly be a little better.

Warranty would most certainly be voided!

Using a gear ratio calculator, here are some before/after calculations in engine RPM....
3rd gear, 60mph
G70 FD: 4417 RPM
G80 FD: 4880 RPM

So the RPM difference would certainly be noticeable. Below is a shift point graph comparing the two...

G70 FD





G80 FD





If the gears actually fit (which I think there is a good chance they do), it would be awesome to see the change in 0-60 and 1/4 times. Hopefully somebody does this some day... Maybe if I were still single or my kid(s) were old enough to take care of themselves I'd do the swap. But, as of now, I simply don't have the time to take apart my car that extensively!

 

[canucklehead604]

I never hear of changing gears any more. Used to be fairly common. How much difference do you think there would be in performance?

Will it void the warranty? The engine will have more rpm per mile if it was even noticed.

^ over on the G37 forum i used to frequent, one of the common acceleration mods was a gear swap. lots of guys did it (well, some) and extolled the improvements off the line. fuel economy and highway rpms took a hit, of course. i don't recall any data showing what the impact was for acceleration times, but the feedback was universal. i think it was a 4.083 that got the best reviews, up from factory ~3.35 or something like that.

 

[EdP]

It's a good question. The difference in performance wouldn't be huge, but it would be noticeable. 0-60 times would certainly be a little better.

Warranty would most certainly be voided!

Using a gear ratio calculator, here are some before/after calculations in engine RPM....
3rd gear, 60mph
G70 FD: 4417 RPM
G80 FD: 4880 RPM

So the RPM difference would certainly be noticeable. Below is a shift point graph comparing the two...

G70 FD

View attachment 20333



G80 FD

View attachment 20334



If the gears actually fit (which I think there is a good chance they do), it would be awesome to see the change in 0-60 and 1/4 times. Hopefully somebody does this some day... Maybe if I were still single or my kid(s) were old enough to take care of themselves I'd do the swap. But, as of now, I simply don't have the time to take apart my car that extensively!

Has to be good for the 0 - 60 times, but according to the graph it limits top speed to 200. Trips to the grocery store will take longer.

 

[Toddasaurus]

Has to be good for the 0 - 60 times, but according to the graph it limits top speed to 200. Trips to the grocery store will take longer.

Oh don't you worry, the calculator I used only allowed up to 6 gears to be used. The graph doesn't show 7th or 8th. Those would be limited up to like 255mph or something. Haha.

But it's all a moot point. Everyone knows you only need to hit 88mph anyway in order to remove the restrictions of time.

 

[G-534450]

I never hear of changing gears any more. Used to be fairly common. How much difference do you think there would be in performance?

Will it void the warranty? The engine will have more rpm per mile if it was even noticed.

I'm sure it would void the warranty. But going from a 3.54 gear to a 3.91 gear will definitely increase acceleration noticeably