Close ratio boxes, tell me whats good and not so good

[charged]

Close ratio boxes, tell me whats good and not so good

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Looking at going to a ratio box in my IP car, at the moment I run a 4age 20V Blacktop thats making 185hp at the fly, the rev limit is 9200rpm and its got a T50 with standard ratios and a Tseries diff with 4.77 gears also running 185/60/13 Yoky a48s. At Mallala I only get into 4th gear down the back straight and I dont change gears down the smaller straights . Will a ratio box help that much, also what type of box synchro, straight cut dog box ? Most of the other u2l cars run ratio boxes and change gear at least twice on the short straights. heres a vid of my thing round Lala as you can see it struggles a bit.

What box also Albins, PPG, PAR, Quaife ?

Vid round Mallala
http://www.youtube.com/watch?v=SojJC_nFdgs

These are the ratios Im looking at

1st 2.347 (high first gear)
2nd 1.733
3rd 1.379
4th 1.144
5th 1.000


Gear Km/h per 1000 RPM Km/h @9000 RPM Km/h @9200 RPM
--------------------------------------------------------
1 9.24 83 85
2 12.52 113 115
3 15.73 142 145
4 18.96 171 174
5 21.69 195 200

Km/h RPM (in Gears)
-------------------------------------------------


Gear Change RPM drop (change @9000) RPM drop (change @9200)
-------------------------------------------------------------
1 -> 2 -2354 (to 6646) -2407 (to 6793)
2 -> 3 -1838 (to 7162) -1879 (to 7321)
3 -> 4 -1534 (to 7466) -1568 (to 7632)
4 -> 5 -1133 (to 7867) -1158 (to 8042)






What I run now standard T50 ratios

Ratios
1st 3.587
2nd 2.022
3rd 1.384
4th 1.000
5th 0.961

Gear Km/h per 1000 RPM Km/h @9000 RPM Km/h @9200 RPM
--------------------------------------------------------
1 6.05 54 56
2 10.73 97 99
3 15.68 141 144
4 21.69 195 200
5 25.20 227 232



Gear Change RPM drop (change @9000) RPM drop (change @9200)
-------------------------------------------------------------
1 -> 2 -3927 (to 5073) -4014 (to 5186)
2 -> 3 -2840 (to 6160) -2903 (to 6297)
3 -> 4 -2497 (to 6503) -2553 (to 6647)
4 -> 5 -1251 (to 7749) -1279 (to 7921)

[finney]

As for which manufacturer to go with I've got some friends running PAR straight syncro boxes and one with a dox box and they haven't had any issues whatsover in regards to reliability - both have managed to kill nismo mechanical diffs and haven't had any damage the PAR gearsets with the abuse they've been given.

I believe they will only provide warranty on the boxes when they run NEO oil in them aswell which you may want to confirm as it's not exactly cheap in comparison to other oils out there.

[Celica RA45]

look at the trd gear sets they use a 2.34 1st
1.60 2nd
3rd is 1.19 4th 1 to 1
and 5th is .886
my mates ke25 corolla runs around winton with a 4.55 ratio and uses 4 gears only 1.38.5 with std black top 20 v
at island uses 5th and also calder

[lexsmaz]

Watched your video, not to bad, except for missing the gears a few times, show's how much distance you loose with a couple of miffed gear changes ... did you think of runing an auto ? ( sorry only joking ) ... all seemed ok except you need some more power i reckon, or maybe try runing a taller ratio diff as in a 4.9 ? or higher, that might help a bit ? ..

[Ben Wilson]

I have seen people run RWD 6 speed gearboxes with a low diff. You get an ultra low first gear for dribbling around the pits, and a good close ratio 5 speed gearset...

[Celica RA45]

early model came with 5 speed so you cant use a 6speed box unless it came from factory
but a 6 speed would be over kill in a ke25 corolla
palm side in nz has ae86 trd gear sets for 2250 nz dollars and are in stock

[charged]

Watched your video, not to bad, except for missing the gears a few times, show's how much distance you loose with a couple of miffed gear changes ... did you think of runing an auto ? ( sorry only joking ) ... all seemed ok except you need some more power i reckon, or maybe try runing a taller ratio diff as in a 4.9 ? or higher, that might help a bit ? ..

Yep that was actually the nephew missing third a few times in Race 1 and yes one stuffed gear change and hello 5 car lengths. The shifter is getting rebuilt this week as its a bit like a spoon in porridge at the moment.

More power is on the cards in 2010 off season either a full on 3s NA or a turbo version of the 20V, still indecided about which way the car will go

[rick q]

I have an Albins CR gearset in my Clubbie running through a 4.44 diff with 15" rims, and it's the best thing I've ever done for it. On the track, all ratios are usable (except 5th). It's conventional with synchros - not a dog box.

The downsides with my CR box are hill starts with the high 1st gear, and running motorcycle revs on the highway.

From what I've heard, dog boxes are great for the track but hard to live with on a daily basis - maintenance can be pretty high too, with the dogs needing fairly regular replacement / inspection (annually?) depending on use and abuse.

Send me your email address, and I'll flick back a graph I made to help choose the ratios to work with.

[gixer]

Hey John, that set of close ratios you intend to use.....are they the Quaife set???(ratios look like it) if so, have you save heaps of cash.....VERY EXPENSIVE!!!!

[oldcorollas]

Route6 close ratio box
http://page16.auctions.yahoo.co.jp/jp/auction/u28187086

[charged]

Yeah jamie, the quaife are 3000 pounds and Im poor ... probably going to go a Albins set with a high first and a closer 2nd, 3rd and 1:1 4th and .86 5th. Clint rekons a closer ratio will help the car get out of corners and keep it on the boil. Going out this weekend to log some speeds at turn 2 , southern northern and the esses and see what ratios will suit. Having a punt of clints car also, so I should at least bust out my first sub 20 round Lala..... pity it wont be im my car

[Gavatron]

You guys at the auto elec workshop now? Saw the lights on through the front on my way past.

[charged]

yeah clints putting his new shocks in tonight and new camber tops and robs working on his car....... my turn tommorrow night, new rear calipers, weld exhuast and a general checkover...... farkin racecars, spend more time fixing them than driving them

[Gavatron]

Give us a yell if you need a hand. I;m all up for working on things I don't normally get to ;P At trade school 2 streets over this week.

[takai]

Give us a yell if you need a hand. I;m all up for working on things I don't normally get to ;P At trade school 2 streets over this week.

Shouldnt you be working on your own car

As for CR boxes, i would be looking at going to 4.9 or 4.7 rather than the 4.5 you have now. Much more economical, and brings the ratio down nicely in line with Mallala.