FJ20t gear ratios

[Riceburner]

I'm wondering if anyone knows what ratios FJ20t boxes have? I done a bit of research and seem to get different answers. Ideally I'd like ratios close to a 260z box, .8 fifth is a must!.

 

How accurate is this? According to this info the ratios aren't too bad.

http://members.optushome.com.au/amaxeng/five10/gearbox.htm

[dat2kman]

Dont use a fj turbo box thenratios are stocko L series.ie 3.3 first.

 

Grab a 260 box first should be 2.9.

Or,,i have a complete L type close ratio, 2.6 first,,,

Or,,,

I can sell you a new 2.4 close ratio gearset, you fit it into some stocko L series box,,,

Or,

,

,

,

Or, dunno, my brain hurts!

[peter mc]

the reason we use the fj20t box is so we can use the wide gear , because the stock L gear size just wont hold up with the torque  the motors are making , the fjt box with a gear set from kameri is a good thing ,

[Riceburner]

My current 260z box has now just started to get bearing noise on top of the other issues.

 

With the site above the FJ20turbo box ratio's are 3.657, 2.177, 1.419, 1.000, 0.833

 

I wanted to avoid buying new gearsets and use that money to rebuild the newer box.

[benny]

My current 260z box has now just started to get bearing noise on top of the other issues.

 

With the site above the FJ20turbo box ratio's are 3.657, 2.177, 1.419, 1.000, 0.833

 

I wanted to avoid buying new gearsets and use that money to rebuild the newer box.

 

 

why dont you go with a newer sr or z32 box??

[Riceburner]

I thought the FJ box had the same size gears as SR?

[peter mc]

they have the same size gear Gareth , there 20mm wide 260 box is 18 , also the gear sets have better gear strenth , also the bearings are the same as the sr box  , its only when you go to the rb25 and vg30 boxes that you get a bigger gear sets and bearings , much stronger but much harder to fit to the L motor ,

the fj t box with a gear set is more than up for your engine mate ,

[benny]

surely a sr box would be cheaper then an fj too?? A guy in the states makes a kit to hook up a z32 box. See here for info -http://forums.hybridz.org/topic/101735-z32-transmission-adapter-kits-for-l28/

[peter mc]

with the sr box you also have to mod the floor and shifter hole and the plastic need work to fit the shifter , with the fj box  the shifter is like the L box  no mods needed  only have to swop the bellhousing

[d3c0y]

Don't forget you have to shorten the tail shaft too with the SR.

 

 

With the Z32 even after you get the adapter which is close to $500 landed you still need to:

"This adapter is for the DIY crowd and will require machining the z32 [/size]__af_placement_id--[AFF-PLACEMENT-ID].html]bellhousing[/size] and fabrication of a transmission mount and [/size][/size] along with shortening the shifter linkage."

[/size]

[/size]If he wants a 0.85 5th then you will have to change the 5th gear too and at the end of the day it may still need a rebuild as 3rd and 5th syncros are a bit notorious in these boxes.

[/size]Z32 gear ratios:

[/size][table][tr][td]1st gear ratio:[/td][td]3.214:1 man / 2.785 auto[/td][/tr][tr][td][/td][td][table][tr][td][/td][/tr][/table][/td][/tr][tr][td]2nd gear ratio:[/td][td]1.925:1 / 1.545 auto[/td][/tr][tr][td][/td][td][table][tr][td][/td][/tr][/table][/td][/tr][tr][td]3rd gear ratio:[/td][td]1.302:1 / 1.00 auto[/td][/tr][tr][td][/td][td][table][tr][td][/td][/tr][/table][/td][/tr][tr][td]4th gear ratio:[/td][td]1.000:1/ 0.694 auto[/td][/tr][tr][td][/td][td][table][tr][td][/td][/tr][/table][/td][/tr][tr][td]5th gear ratio:[/td][td]0.752:1 / na auto[/td][/tr][/table]

[peter mc]

Gareth the ratio we use in the fjt box are    2.43  1.68  1.26  1  .86 or .75 and we use a 4.3 diff with it  for most L motors

 

[dat2kman]

They're Albins ratios.

 

With SR box, they are 50 mm longer o/all, ie need to shorten tailshaft by 50 mm

The gearstick in a sr box will come up in centre of gearstick hole in floorpan of 260 shell.

The box to floorpan mount is 30 mm rearwards compared to L box in a late 240 or 260 floor.

 

Early 240 floor ( old style box mount) much easier, just drill two new holes in floor, ans a couple bits of rectangular 4 mm thick plate and usual bolts.

Later, use a couple pieses 120 mmx80 mm 12 mm thick rubber, and a piece of 6 mm pate, drilled with four holes to allow for 30 mm offset, the stock 260z box to floor mount gets two holes drilled in the dimples. Pretty easy.

 

Yes the sr as well as ca or rb and fj box will need a sr bellhousing, a bit of jiggling around with front countershaft bearings, and check the 1/2selector rod diam as bell may need a 16 mm drillbit into the CORRECT selector support hole.

 

For cluster clearance either plunge face cut inside of bell by 2 mm ( makes it weak, i dont like that) or,

Remove/modify the anti rattle tooth gear at front of lower countershaft.

 

If wanting to use rb20det box, stick comes up at front of the gearhole, but tailshaft remains stock, ie rb20det box is same length as L B type box, BUT these have a .75 fifth. Same with VL commo ( rb30) non turbo

The sr boxes have a .83 fifth

 

Gareth if you are after any of these, i have a few of each, and can supply close ratio sets for any of them.

[Riceburner]

Pete, is that an aftermarket gear set?

 

Is there a specific model or any way of telling which FJ box has the .83 fifth gear? I'm only running a 4.1 FD so won't want any bigger overdrive.

 

Jason & Pete, could you pm what sort of price I'd be looking at for an FJ gearset? It may not be in the budget to do a full gear set, so I may just end up changing 5th if its .75

 

I like the idea of the FJ box, seems less work, smaller and lighter than later models?

[d3c0y]

 

I dont see how the FJ box will weigh any different or be smaller than an RB or SR box, but is the easiest to fit, this is why i went this way.

 

 

Budget around $3500 for a rebuilt box with a gear set in it.

[NZeder]

If installing the Kameari gear set into an FJ B box why not just install the Kameari gear set for the L6 B box?? surely they are the same gear set?

[Riceburner]

$3500 is double my price range, I don't want a new gear set if I can avoid it.

 

I guess I need to try and find which cars had the FJ box with the .83 fifth gear. Buy one and get it rebuilt.

[dat2kman]

I got a couple of fjt boxes here, you dont need bellhousing, swap your bell over.

 

I'll pull them out over weekend and check them over, and make sure they have the 5th you want.

Easy enough to crate it up and get it to a transport depit near you,

 

IIRC, both are in pretty good cond, may not need anything, just bolt in and go!

[Riceburner]

Pm sent

[NZeder]

what box have you got right now? A box or B box? I know RB 71C you can swap over the 5th - so I assume the B boxes are the same too - I would have to check part catalogues to see if the numbers are the same etc. So if the 71B are like the 71C you should be able to take the 240z/260z 5th and put that on the FJ - 5th is usually the same size/width well the are in the 71C IIRC.

[Riceburner]

I have a 260z box, but its quickly becoming junk, the syncros are very very tired. I have recently found what looked to be a gear tooth (4mmx5mm chunk) in the oil. 2nd to 3rd up shift on track sounds like a sequential box.

 

I have also seen someone strip 5th gear on track, locked the box and rear wheels completely. I ran in the same group as him at nationals and was able to see I an now a fair bit quicker. Got me thinking.

 

I thought if I'm going to rebuild a box I may as well get something a bit stronger.

[Xnke]

Look for a later C-box...little more work to get together, but much stronger.

 

1995+ FS5W71C gearboxes are much improved strengthwise versus the older FS5W71B units. They are still just a front case swap away...and don't use the small countershaft bearing if you are concerned with strength. Of the fifteen damaged boxes I've had apart in my shop in the last two years, I have never found a box with severe gear tooth damage, without finding either the front countershaft bearing failed, or the pilot shaft bearing failed. The later boxes have a bigger pilot shaft bearing, as well as the 62mm countershaft bearing, 20+mm wide gears (the box in my garage is 22mm wide, except the input shaft and the 1st gear set being 24mm wide.)

[peter mc]

HAHAH man we smash 5th gear all the time on them at PI , the gear splits in 3 bits , i think Gordo has done it 3 times , thats why we have been using the fj20t box , runing 300+hp engines at 7500 for the hole time down the strate at PI in 5 gear  just kills the standard gox and gears . the cheepest setup is a turbo box with your bellhousing on it , then save up for a close ratio set so it stays in the torque all the time

[dat2kman]

So whats stronger, got bigger mainshaft, thicker gears, more supported selectors, better synchro setup.

Fj20det 71 B type overdrive fifth

Or

Sr20det 71 C tupe/rb20det 71 Ctype overdrive fifth.

[peter mc]

same gear strenth ,  with a gear set there up for about 330ftlb  stock around 290 yes they will take more , but its only a time thing , blokes smash SR boxes with ease with a stock motor .

 

the stock L box will be up for about 220ftlb at 240 its only time

[Xnke]

Yes, you'll smash 5th gear in ANY of those transmissions, including the FJ turbo box, at the power levels you're looking at. They're only 16mm wide in most of the boxes and 18mm wide in any of the rest I've ever seen...Just get a pair of 5th gears machined to fit the later box, if you can work around the ratios. I don't drive 7500RPM in 5th gear, because I know the C-box stock 5th gears won't handle it. They just don't look very strong compared to the rest of the gears. I have a metal shaper setup for cutting gears and internal splines on, but it's not working just yet and I haven't had time to futz about with it. I'd like to machine a 22mm wide 5th gear set  for these boxes from 4140-prehard or 9130 and deep-case them. I bet that'd fix 5th at PI, Peter!

 

The 1995+ transmissions run a strong roller bearing on the rear countershaft plus the tailshaft ball bearing up top, and the later boxes have much stronger-looking support in the case for both of those rear bearings. If I hadn't just sealed up the one in the shop floor I'd take some comparison shots for you. I am still trying to find a 24mm wide countershaft gear instead of the 22mm wide one I have, to match the input shaft gear in the box I've got built for my car; but so far, no luck. That would leave me with a 24mm input set, 1st gear set, 22mm 2nd gear, 3rd gear, and an 18mm fine-mesh 5th gear. There is plenty of room to machine a 22mm wide 5th gear set in any ratio you want, and not have to buy the whole countershaft assembly.

 

Gear damage on 1-4 is almost always bearing failure first, and I've heard of shift-fork breakage causing it to get locked into two gears at once, too, but haven't seen it. Usually broken forks just lock up the trans in one gear, but if you try hard enough...

 

Might want to look into just machining a replacement the 5th gear set, might be a more accessable option. Not sure if you can deal with the ratios you all got in the Southlands compared to what came here; most of the heavy-duty 95+ -C and -E type boxes here are from heavier box trucks and SUV's, and have close-ish ratio sets and 4.08 and 4.375 rear end gears, with a VG30e or KA24DE in front of them. The VG33ER-equipped SUV's and pickups had 3.321, 1.912, 1.517, 1.00, and 0.745 gearing, the VG30E boxes have 3.321, 1.902, 1.308, 1.00, 0.745 gearing.

 

Those SUV's aren't real common with those drivelines though, they usually have the FS5R30A and a VG30DE or VQ series engines nowadays.

 

The box in my floor actually came from a 1998 2WD Frontier SE, VG33ER engine and a 4.08 C233 solid rear axle. I'm hoping the odd ratio for 3rd gear was chosen for supercharger service, since that's what I'll be using it for.

 

EDIT: You guys are hitting 165++ on PI? (7000RPM, 0.833 5th gear, 245-45-17's on a 3.90 rear end)