best final drive question

[stewdaddy23]

So, with the 523/568 build about to start here soon. what is the advice for the final drive to use.
Car usage-
Autocross
Roadrace
daily driver 2+ days a week when done

dragrace- maybe if i feel like it but not the main deal

not worried about MPG on the highway

so. 3.50 or 3.77 or what??

[cordes]

How much does your car weigh? 2.2 or 2.5? What size tire? How much power are you making? Which turbo are you running? There are a ton of factors which go into choosing the best FD IMO.

[stewdaddy23]

Ok.GLHS close to stock weight, 2.2, gonna shoot for 300-350hp with the eng, 235/50/15 tire. does that help?

[Abkshelby]

I'm not an expert on final drive ratio's but I'd say use the 3.77 one since that is close to the original ratio in the GLH and GLHS.
Others that autocross and race will give more help on this I'm sure.

[cordes]

If it were me I would put the 3.50FD in there. You'll be making more than enough power to use it.

[Vigo]

Id go for 3.5 too. Autocross/road race means unloaded inside tire means wheelspin, taller gears will make that easier to manage. Plus, taller 2nd comes in handy frequently in autocross.

[RoadWarrior222]

Autocross = leave it in second, keep both hands on the wheel, use your left foot on the brake

[135sohc]

Id go for 3.5 too. Autocross/road race means unloaded inside tire means wheelspin, taller gears will make that easier to manage. Plus, taller 2nd comes in handy frequently in autocross.

There will also be an obx in the mix.

[BadAssPerformance]

The "leave it in 2nd" is good if you have a long enough power band, which the 3.5 will give you, however, AutoX is all about quick accel and decel so the highest numerical gear ratio is usually preffered... this is why you see cars on 13" rims.. MOAR GEAR LOL, well, that and they weigh less

For reference, a 555/3.50 FDR in my T2 Shadow, will do over 100mph in 3rd... l o o o o o o o o o o o n g gears

[stewdaddy23]

Hmmmm. the 525 has the 3.56 in it. and its ok. I bought a 3.50 set up so we'll se how it goes once it's in the car. The eng makes about 215 right now and hauls butt as is. wounder what it will be like with another 150 Hp on the track/road course. I'll keep evryone up to date once I get all the stuff to 135sohc, get it buit, and get it back in the car. Thought these cars were cheap fun? LOL

---------- Post added at 12:07 PM ---------- Previous post was at 12:05 PM ----------

Thanks again to everyone. Don't worry I'll have more questions comming.

[rbryant]

Hmmmm. the 525 has the 3.56 in it. and its ok. I bought a 3.50 set up so we'll se how it goes once it's in the car. The eng makes about 215 right now and hauls butt as is. wounder what it will be like with another 150 Hp on the track/road course. I'll keep evryone up to date once I get all the stuff to 135sohc, get it buit, and get it back in the car. Thought these cars were cheap fun? LOL

---------- Post added at 12:07 PM ---------- Previous post was at 12:05 PM ----------

Thanks again to everyone. Don't worry I'll have more questions comming.

Don't forget that the gears in the 568 are much longer than in a 525.

The 568 with a 3.85 is actually pretty close gear wise to the 525 except 5th gear is much shorter so the 3.85FD 568 kind of stinks on the highway. Someone should look into making a custom .65 5th gear for the 568 I think it is actually the only gear that isn't integrated into the input shaft making a custom gear possible. If someone ever wants to lose a bunch of money making one let me know and I would be interested in purchasing one to offset your loss.

525, 520, and Pre 92 523

1. 3.29
2. 2.08
3. 1.45
4. 1.04
5. 0.72

555 and 90 568

1. 3
2. 1.89
3. 1.28
4. 0.94
5. 0.71

91+ 568

1. 3.31
2. 1.89
3. 1.28
4. 0.94
5. 0.71

92+ 523

1. 3.31
2. 2.06
3. 1.36
4. 0.97
5. 0.71

When you multiply out the 525 with a 3.56 FD it is:

1. 11.7124
2. 7.4048
3. 5.162
4. 3.7024
5. 2.5632
   

When you multiply out the 555/568 it is:

1. 11.55 or 12.74 (for the 91+)
2. 7.2765
3. 4.928
4. 3.619
5. 2.7335

Speed at 6k RPMs and 205/50/15 tires:

568 with 3.85

• 36 (or 33 on 91+)
• 57
• 84
• 115
• 152

525 with 3.56:

1. 35
2. 56
3. 80
4. 112
5. 162

So the real gear ratio is actually longer for gears 1(for the '90 only), 2,3, and 4 in the 568 when compared to a 525 with a 3.56FD.


-Rich

[RoadWarrior222]

Someone should look into making a custom .65 5th gear for the 568 I think it is actually the only gear that isn't integrated into the input shaft making a custom gear possible. If someone ever wants to lose a bunch of money making one let me know and I would be interested in purchasing one to offset your loss.

Heh.

Though I suppose, if you went to a yard with a wide selection and spent all week tearing open gearboxes, you might come across something close to that and workable with mods.

[rbryant]

Heh.

Though I suppose, if you went to a yard with a wide selection and spent all week tearing open gearboxes, you might come across something close to that and workable with mods.

Nahh I was thinking of a fully custom gear. I know that there have been custom gears made like that in the past so it is possible but probably very expensive and not worth it.

I think I will be fine on the highway with my 568/3.77FD.

-Rich

[135sohc]

We cant get something as basic as shift fork pads past the discussion stage.... New gears are asking a bit much

[RoadWarrior222]

Shift fork pads lack sex appeal. They lack identity. If someone's into cars do you call him a "shift-fork-pad-head"??? Even the term itself sounds weird, I just shouted it out now and my wife looked at me like I was crazy. Gears for the glory!

[rbryant]

We cant get something as basic as shift fork pads past the discussion stage.... New gears are asking a bit much

That is why I prefixed it all with "if anyone ever wants to lose a lot of money making them."

-Rich

[BadAssPerformance]

We cant get something as basic as shift fork pads past the discussion stage.... New gears are asking a bit much

I beg to differ.... they are in the testing stage

[GLHNSLHT2]

I chose my 3.50 geared 523 because 1-4 are pretty close to 1-4 overall in the 555 that was in it. I like it with the 2.5 in my daytona. I think it'd autox really well with the 205/60 15's.

[135sohc]

I beg to differ.... they are in the testing stage

So 2012 will be the big year right ?????

[BadAssPerformance]

So 2012 will be the big year right ?????

I have dims off the ones reeves loaned me, need to find my sketches of the others... stay tuned