C52 vs C56 Gearbox

[B1NZ]

So I currently deciding which gearbox to use in my Ae92 Rally car with smallport 4AGE, Have been talking to friends and they seem to have differing opinions as to which gearbox is best to use, I currently have a C50 in the car and I find there seems to be a huge jump from 2nd to 3rd gear so I am looking to get rid of this jump with a closer ratio gearbox, I have the specs of each gearbox below but am not sure what the numbers mean? Any Idea on which box I should use?
I have a C52 and a C56 available to use with a TRD LSD unit ready to go into it

C50 Gear Ratios:
1st: 3.545
2nd: 1.904
3rd: 1.310
4th: 0.969
5th: 0.815
Reverse: 3.250
final drive: 3.722

C52 Gear ratios:
1st: 3.166
2nd: 1.904
3rd: 1.310
4th: 0.969
5th: 0.815
Final: 4.058

C56 Gear ratios:
1st: 3.166
2nd: 1.904
3rd: 1.392
4th: 1.031
5th: .815
final drive: 4.312

[KinLoud]

C56 for 2 reasons

1 - the ratios from 2 to 3 and from 3 to 4 will help keep you in the power band

2 - final drive ratio will give you higher revs for the same road speed in all gears so more acceleration at any road speed.

Ken

[ch4ng]

By those numbers the C56 will be the only one that has a shorter 3rd and 4th ratios gear ratio. However it also has a longer 1st gear as well which will mean a higher top speed in 1st (but it'll take a bit longer to get there)

If you're happy with your current 1st gear would you consider using your current 3.545 1st gear in the C56 box

I had a play with this calculator and have a look at the road speed chart (note the speeds are in Miles per hour)

Enter the details you have including tyre size and you can see the speed difference at any given RPM

eg: using the C50 and C56 details and a 195/60R15 tyre size it showed at 6000rpm

C50: speed in KMH
1st 53.1
2nd 98.2
3rd 143.2
4th 193.1
5th 228.5

C56: speed in KMH
1st 49.9
2nd 82.1
3rd 112.7
4th 151.3
5th 189.9

[KinLoud]

I don't think you can mix and match gears like that. But you might ba able to swap the final drive ratio? Starlet fans will know.
Tall first gear is the way to go so avoid C50

Question. Where did you get the final drive ratios from?
Did you work it out yourself or online?

The final drive ratio generally depends on the wheel/tyre size
Poo spec corolla with 13" wheels will have a 3.7ish ratio.
Late model A series corollas with bigger wheels will be more like 4.1 4.3ish
I don't know if the 4age gearboxes have different final drive ratio compared with 4afe?

Ken

[B1NZ]

just from a website I found, so final drive may be incorrect or may be off the original vehicle it came from?

Im not too worried about first gear tbh as this is used to get me off the line at the start of a stage and then 2nd, 3rd and sometimes 4th are used mostly.

My other option was to get the TRD style gearset made and installed which was a lot more

[crispy'86]

I'd choose the c56 box as the ratios are closer between 2 and 3. Was going to run with this in my fx race car but funds put a halt to that seeing the track again, as i too had the trouble of finding 2 to 3 was too much of a drop especially going round some of the turns at ruapuna i figured the 56 was better. Unfortunately i never got that far

[loose_unit]

I would go c56 also, have a c56 gearset and final drive in my ep82 and the difference in 3rd and 4th gears is really noticable. I have a really peaky powerband (5500-8500) and I found it much easier to keep it on power with the c56 setup.

[Mr Revhead]

Yeah given the events you do c56.
Oh, and maybe a nudge bar?

Fit new synchros and bearings when installing the LSD.

[Bazda]

By those numbers the C56 will be the only one that has a shorter 3rd and 4th ratios gear ratio. However it also has a longer 1st gear as well which will mean a higher top speed in 1st (but it'll take a bit longer to get there)

If you're happy with your current 1st gear would you consider using your current 3.545 1st gear in the C56 box

I had a play with this calculator and have a look at the road speed chart (note the speeds are in Miles per hour)

Enter the details you have including tyre size and you can see the speed difference at any given RPM

eg: using the C50 and C56 details and a 195/60R15 tyre size it showed at 6000rpm

C50: speed in KMH
1st 53.1
2nd 98.2
3rd 143.2
4th 193.1
5th 228.5

C56: speed in KMH
1st 49.9
2nd 82.1
3rd 112.7
4th 151.3
5th 189.9

Generally 1st gear is really low and its not needed on a race track ever.
Its there to make life easy for every day driving.

Taller 1st gears mean you can close the gaps between the following gears and have better ratios

[B1NZ]

Thanks for the help guys, C56 it is then

[TRD Man]

1st gear is essential in a rally car.

Generally, with the same final drive, the differences in ratios between C52 & C56 aren't enough for you to notice and won't make an ounce of difference to your stage times.
The 4.3 diff ratio is interchangeable between the boxes so I'd suggest you go with the box which is in better condition.
If it's a toss up - C56 is your man.
Make sure that the LSD is in 2 way mode before installing.

[B1NZ]

1st gear is essential in a rally car.

Generally, with the same final drive, the differences in ratios between C52 & C56 aren't enough for you to notice and won't make an ounce of difference to your stage times.
The 4.3 diff ratio is interchangeable between the boxes so I'd suggest you go with the box which is in better condition.
If it's a toss up - C56 is your man.
Make sure that the LSD is in 2 way mode before installing.

I actually did a search before this post and I saw a discussion where you said this about 2 way LSD, How do you change it to this specification?

What are the pros/cons of doing this?

[neo]

My Speadsheet with comparions between c52 and c56, TRD and Chelles crazy Mitsi Mirage short ratio box.

http://ae101.tappsville.com/hosted/GearRatios.xls

And for shiz and giggles, enter the file name wrong in the URL above

[TRD Man]

I just typed a long answer & it vanished when I went to upload it. God I hate that.

Essentially we had a number of FWD Corolla rally customers who were smashing the shallow ramps on over-run in new diffs. This is not a part you could buy but we were very lucky to get some out of Japan.
They come new in the 1 & 1/2 way position and by changing to the 2 way mode there was no room for the spider to move and the problem went away.
Whether there's a downside at all depends on how you drive. In 2 way it could bite on over-run and induce a bit of understeer. You should have your foot hard into it anyway.

Some nice data there Neil. The AE011 TRD kit actually works very well in the gravel with a 4.733 ratio.

[QikStarlie]

The 4.3 diff ratio is interchangeable between the boxes so I'd suggest you go with the box which is in better condition.

this is true^ but its quite a bit of work. need to swap over the output shaft, to swap to a different final drive. which means all the gears have to come off the shaft.
when swapping to 4.3 final in the starlet boxes. i used to just dump a complete gearset and final drive from a 4age c56, into the starlet case. was the easiest way.

[B1NZ]

I just typed a long answer & it vanished when I went to upload it. God I hate that.

Essentially we had a number of FWD Corolla rally customers who were smashing the shallow ramps on over-run in new diffs. This is not a part you could buy but we were very lucky to get some out of Japan.
They come new in the 1 & 1/2 way position and by changing to the 2 way mode there was no room for the spider to move and the problem went away.
Whether there's a downside at all depends on how you drive. In 2 way it could bite on over-run and induce a bit of understeer. You should have your foot hard into it anyway.

Some nice data there Neil. The AE011 TRD kit actually works very well in the gravel with a 4.733 ratio.

Cheers for the info, So it's more of a longevity thing then, So how do you change it from a 1.5 to 2 way?

[85AW20v]

Have a look here. Look at the top link.....
http://forums.toyspeed.org.nz/viewtopic.php?t=72363

[B1NZ]

Cheers for the pics, Im not sure if it tells me how to make this change though does it?

All I get out of that is I can see how many parts are inside and how many I can potentially misplace

[85AW20v]

It's all to do with how you assemble the spider carrier. When you drop the spider with the four pinions on it back in, it'll fit in either of the cutouts. The even angled sides = 2 way - or the uneven angled sides = 1.5way.

[DexGT]

seeing as it's not fitted yet I can easily show you sometime if you want. I assume your co driver probably knows how too