The "Mongrel" gearbox for the 4x4 guy(and the land speed record guy)

[Master-O-Turbonics]

So I built a FS5W71B gearbox into a stubby case...
I took what seems to be an 81-83 280zx transmisson(only thing wrong with it was reverse was messed up)
and a stubby transmission that came out of a later 720 4x4 truck.

Here are the criteria I was going for:
1. had to end up with the stubby tail housing and output shaft because of driveline space concerns
2. as low of a first gear ratio as possible
3. as little overdrive as possible.

I had several parts transmissions laying around to pull parts from
here is what I ended up with.

SD22 input shaft/ counter gear (1.52 ratio) Same ratio as the 720 4x4 stubby and early 720 4x4 long tail 4 speed but those were damaged and/or worn excessively

81-83 280zx full gear set, 280zx main plate and shift rods.

reverse gear idler gear off of a maxima transmission to replace damaged 280zx gear(same depth as the 280zx reverse idler)
I ended up with ratios of

3.678 1st gear
2.24 2nd gear
1.57 3rd gear
1.0 4th (duh)
.898 5th gear.

With the 33" tires currently and 4.88 differential ratios, that puts me at highway speed of 70mph at around 3000RPMs

1st gear ratio in 2:1 low range of 3mph at 1000
and 15mph at 5000.

This would probably be undrivebale behind an L20B (on the highway) but I'm putting it behind an L28 in front of it so it should have plenty of torque.

Just thought I would post this different "Mongrel" setup for the 4x4 guys.

[Stoffregen Motorsports]

Nice job. I enjoy a good 4x4 discussion...

[]2eDeYe]

Nice work. :cool:

[datzenmike]

There were 3.592 first gear 5 speeds in all 2 and 4wd '80 720s and also all the diesels. I guess every little bit helps with your 2:1 trans case.

 

This is very interesting as I have a page of notes sent to me (you maybe?) for going the other way. It's an early 620/280z/Maxima or 2wd 720 5 speed 3.321 first. The input and counter gears are swapped from a 280zx to give a 2.972 first gear ratio and 0.745 overdrive.. In effect making an even closer ratio. Didn't bother exploring the direction you did as not needed in a car... some good info!

[datzenmike]

Yes your diesel box has a first ratio of 3.592 so the main and counter drive gear set must be 21/32= 1.523

 

A 22/31 gear set ( 1.409) gives a first of 3.321 with the diesel internal gear set.

 

A 29/23 gear set ( 1.261) gives a first of 3.062 with the zx 5 speed internals.

 

The same 29/23 gear set used with the diesel internal gears gives a first of 2.972

 

I have a set .... looks like 21/32 (as I remember it was from a diesel too)

 

Hmmm I'm getting your mongrel having a 3.701 ratio with the '81-'82 zx box. Your 1.523 X 2.429 (1st gear) = 3.701.

[Master-O-Turbonics]

Yes your diesel box has a first ratio of 3.592 so the main and counter drive gear set must be 21/32= 1.523

 

A 22/31 gear set ( 1.409) gives a first of 3.321 with the diesel internal gear set.

 

A 29/23 gear set ( 1.261) gives a first of 3.062 with the zx 5 speed internals.

 

The same 29/23 gear set used with the diesel internal gears gives a first of 2.972

 

I have a set .... looks like 21/32 (as I remember it was from a diesel too)

 

 

Hmmm I'm getting your mongrel having a 3.701 ratio with the '81-'82 zx box. Your 1.523 X 2.429 (1st gear) = 3.701.

probably my rounding error lol

here is a pic of the gearset. did a little "extra" work to it....

When in Rome....

 

The stubby gearbox had the larger counter shaft bearing, like a 71C transmission, but definitely has a 71B style shifter.

 

fyi, there is possible a .67 overdrive. See if you can figure that one out. ;-)

I'm gonna go through and put a trans together with that crazy overdrive for another side project...

[datzenmike]

Well a 24/28 tooth main/counter gear combo would give a 0.689 overdrive. Is there such a gear combo? Maybe from a competition box?

[datzenmike]

Huh?

[Master-O-Turbonics]

I'll have to look at my notes.

I have a 5th gear that is different. Think it was out of the Maxima trans. 

I know my maxima trans had the 1.409 input ratio(the only trans of mine to have completely blown up the input shaft) but had a .754 5th ratio, so swap in the 1.26 280zx input gearset and there you go. 

 

For what its worth, The SD22 input shaft is identical to an L series input shaft, pilot bushing area and all. SD22 Countershaft forward bearing is the smaller, standard 71B bearing, not the larger 71C size bearing.

[datzenmike]

The 1.409 gives 0.833

The 1.261 gives 0.745

 

The Maxima seems to have 0.864 5th so I wonder what input gear set that is??? Or are the 5th and counter drives different like you said???

 

All the ones shown that I have are 44 teeth counter and 26 output for a .591 ratio

 

To get a 0.67 OD you would need a 45 tooth 5th counter and a 24 output (5th) gear

 

 

 

Will dig some more through the part numbers. Some list the tooth count on the gears, maybe I'll luck out.

[Master-O-Turbonics]

The maxima(as per my Maxima FSM) has .745 5th gear. I counted the teeth on the input gears and its the 1.409 ratio. The 5th gear does have a different tooth count. Trust me I counted it 3 times thinking there was only one 5th gear. I left my notes at work and just dont remember the tooth count off hand but it is not 44/26 as it was on all of my 4x4/diesel transmissions.

 

45/24 does look familiar, but I will check the notes to be sure.

[Master-O-Turbonics]

Here are the tooth counts. All I cared about were 1st and 5th gears, really. Although I did figure 3rd gear in my custom 4x4 trans. Some of these were damaged but I was able to get a tooth count from them. Everything that I didn't use or keep as spare(all the undamaged inputs/counter sets and 5th gears) went to the scrapper.

 

Input/counter shaft.

SD22                               32/21

stubby later 720 4x4 5spd. 32/21

720 early 4x4 trans 4spd    32/21

280Z 5spd                        32/21

280zx 5 speed (late)          29/23

84 Maxima 5 speed           31/22

 

 

Counter/output

1st gear

Stubby later 720 4x4 5spd 33/14

280Z 5spd                        33/14

Maxima 5 speed               33/14

280zx (late)                      34/14

 

5th gear

Maxima                            24/45

280zx 5 speed(late)           26/44

280Z                                24/45

Stubby later 720 4x4 5spd 24/45

 

 

Here is my 4x4 transmission

32/21 counter/input gear ratio 1.524

1st gear 14/34 = 2.429 * 1.524= 3.702 1st gear

3rd gear 27/28 = 1.037 * 1.524= 1.576 3rd gear

5th gear 44/26 = .591 * 1.524= .901 5th gear

[Master-O-Turbonics]

Super Overdrive transmission

81-83 280zx non turbo input/counter 29/23= 1.261

5th gear 24/45(non-ZX) = .5333 *.1.261  = .672 Overdrive

 

I don't think I would put this behind any engine with serious power(L28ET) or in a heavier vehicle(Maxima)... this would put a lot of stress on the transmission in 5th gear. Heck my L28ET Maxima eats transmissions for breakfast so its time for a 240sx transmission LOL! Maybe its just the 3.54 rear gear that puts the stress on the trans.

[datzenmike]

 

I love this shit.

[Master-O-Turbonics]

Oh yeah, Don't try to mix an 81+ transmission with a pre-81 transmission. (like a pre-81 input shaft on a 280zx transmission) I'm pretty sure it would be ok to swap a 5th gear from any transmission to any transmission, but don't swap anything in the main gearbox area pre-81 and post-81.  

[datzenmike]

Other than the speedo pinion what did you find different? I have an '85 diesel tail on my '79zx 5 speed.

[Master-O-Turbonics]

Other than the speedo pinion what did you find different? I have an '85 diesel tail on my '79zx 5 speed.

There is a slight difference on gearbox length in the main gearbox area by about .010" but I havent quite figured it out yet. The first transmission I built years ago without any info on these transmissions was a mixture of a late maxima trans and very early one(around 80-81) and it ate up the front trans cover and puked all the gear lube onto the ground. If you don't mix early and late you should be safe.

Shift rails have to stay with their main plate. they got larger for the later transmissions. Also some of the later transmissions got double roll pins on the shift forks to rails. I always double roll pin and then safety-wire through the roll pins to add strength to the situation.

[mtngoat]

Cool, thanks for dragging this back into focus. I'm still racking my brain to figure out if I can blend a 3.59 1st with a .7something 5th for my wagon. This thread is required reading for me!

[Master-O-Turbonics]

1.52 (32/21)input, and 33/14 1st and a 24/45 5th gives you the 3.59 1st and .81 5th. 

 

1.41(31/22)input,  33/14 1st gear gives 3.42 1st ratio and 24/45 5th gives .75 5th ratio (this is a stock maxima 5 speed)

 

Stock Maxima is probably your closest thing to a 3.59 1st gear as it has that deeper 1st gear ratio(3.42) but still has really good overdrive.
 

Maxima trans is pretty sweet on the highway and still has good pickup in 1st. Last trans in the maxima was a truck trans and it was good for driving in crawling traffic with the lower 1st gear

[Xnke]

This is interesting. I have an 87 CA20E 200SX transmission in the car now, and a 91 240SX transmission in the floor in the garage.

 

This is the gearbox in the car now, with a 3.54 R200 rear. This transmission needs new bearings and a new 1st gear synchro.

 

S12 CA20E

1st:  3.321
2nd: 1.902
3rd:  1.308
4th:  1.000
5th:  0.833

 

The 240SX box in my floor has the following ratios:

 

1st:  3.321
2nd: 1.902
3rd:  1.308
4th:  1.000
5th:  0.754

 

Does this seem correct to you guys?

[Stupid_fast]

This is interesting. I have an 87 CA20E 200SX transmission in the car now, and a 91 240SX transmission in the floor in the garage.

 

This is the gearbox in the car now, with a 3.54 R200 rear. This transmission needs new bearings and a new 1st gear synchro.

 

S12 CA20E

1st:  3.321

2nd: 1.902

3rd:  1.308

4th:  1.000

5th:  0.833

 

The 240SX box in my floor has the following ratios:

 

1st:  3.321

2nd: 1.902

3rd:  1.308

4th:  1.000

5th:  0.754

 

Does this seem correct to you guys?

This seems like the correct stock ratios for the 200sx and 240sx gearboxes from all the information i've read.

 

 

 

 

 

You guys modding gearboxes have made me curious, would it be possible to mix and match any gearbox combination to get a taller first and second gear than 3.062?  

Or perhaps reproducing the 3.062 1st and 1.858 2nd in the C series(240sx) trans?

[MasterOSkillio]

This seems like the correct stock ratios for the 200sx and 240sx gearboxes from all the information i've read.

 

 

 

 

 

You guys modding gearboxes have made me curious, would it be possible to mix and match any gearbox combination to get a taller first and second gear than 3.062?  

Or perhaps reproducing the 3.062 1st and 1.858 2nd in the C series(240sx) trans?

 

 

Yeah, I saw this thread and it made me a little exited, I was originally looking at maybe swapping a 6 spd into my KA as far as I could see the z33 was the only option. But the z33 would require more work then I want to do (change diff, figure out new spd sensor), and even then the gear ratios were not what I wanted. So I started looking around at other nissan transmissions that I could pull gears from to 1) increase acceleration in 1-4 (esp 3rd and 4th) and 2) change my 5th gear so I could get better hwy mileage. 

 

I found that with various transmissions I that were compatible 4th could not be changed, and the best I could to in 5th was to go from .759 to.745. Which for me means If I am going 70mph @3000 rpm it would change to 70mph @2944rpm. That's not really gonna do too much for me in terms of fuel savings. A.672 would make 70mph be 2700rpm which is nicer. 

 

I was not aware that you could change the input shaft AND gear between transmissions, I was looking at only the gears, but now that I think of it is makes sense is there some source of info where I could see what parts I could swap between transmissions that would be compatible with the FS5W71E that came with the 240sx?

 

Any help would be appreciated

[datzenmike]

The 71C transmission counter and main shaft gears are physically wider than the earlier 71B gears. The 71C synchro hubs are narrower to fit them. This wider gear set is why (well one of the reasons) the 71C can handle twice the power of the 71B.

 

http://720world.com/forum/topics/fs5w71-bc-transmission-faq

[Stupid_fast]

Yeah, I saw this thread and it made me a little exited, I was originally looking at maybe swapping a 6 spd into my KA as far as I could see the z33 was the only option. But the z33 would require more work then I want to do (change diff, figure out new spd sensor), and even then the gear ratios were not what I wanted. So I started looking around at other nissan transmissions that I could pull gears from to 1) increase acceleration in 1-4 (esp 3rd and 4th) and 2) change my 5th gear so I could get better hwy mileage. 

 

I found that with various transmissions I that were compatible 4th could not be changed, and the best I could to in 5th was to go from .759 to.745. Which for me means If I am going 70mph @3000 rpm it would change to 70mph @2944rpm. That's not really gonna do too much for me in terms of fuel savings. A.672 would make 70mph be 2700rpm which is nicer. 

 

I was not aware that you could change the input shaft AND gear between transmissions, I was looking at only the gears, but now that I think of it is makes sense is there some source of info where I could see what parts I could swap between transmissions that would be compatible with the FS5W71E that came with the 240sx?

 

Any help would be appreciated

 

Actually, the 3rd and 4th gears are the best spaced in these gearboxes.  1.308 and 1.0 is just fine.  I have a 0.745 5th in my box and its great with a 3.89 diff.

 

the 1st and 2nd gear in my ZX box are 3.062 and 1.858, a bit taller than the 3.32 and 1.902 in your KA box.   With the taller 1st and 2nd, moving them closed to the 3rd and 4th gears you could run a shorter differential, a 4.375 or even a 4.6.   

Now this rear gearing would suck on the freeway depending on what 5th gear you have ,but with my 0.745 i'll be turning about 3300rpm at 70.  Definitely worth it for the short 1-4 gearing. 

 

See articles on fuel economy vs rpm, less RPM does not always mean better economy.  I agree for the torque of your KA a longer 5th would probably be a bit better but economy won't be effected much by minor changes in the gearing. 

 

The 71C transmission counter and main shaft gears are physically wider than the earlier 71B gears. The 71C synchro hubs are narrower to fit them. This wider gear set is why (well one of the reasons) the 71C can handle twice the power of the 71B.

 

http://720world.com/forum/topics/fs5w71-bc-transmission-faq

 

Ah well, I know there are custom gearsets but I'm wondering any way to combine the C series trans to make a close ratio box?

 

Ah there's only so much you can do messing with stock gearing options. 

[MasterOSkillio]

Actually, the 3rd and 4th gears are the best spaced in these gearboxes.  1.308 and 1.0 is just fine.  I have a 0.745 5th in my box and its great with a 3.89 diff.

 

the 1st and 2nd gear in my ZX box are 3.062 and 1.858, a bit taller than the 3.32 and 1.902 in your KA box.   With the taller 1st and 2nd, moving them closed to the 3rd and 4th gears you could run a shorter differential, a 4.375 or even a 4.6.   

Now this rear gearing would suck on the freeway depending on what 5th gear you have ,but with my 0.745 i'll be turning about 3300rpm at 70.  Definitely worth it for the short 1-4 gearing. 

 

See articles on fuel economy vs rpm, less RPM does not always mean better economy.  I agree for the torque of your KA a longer 5th would probably be a bit better but economy won't be effected much by minor changes in the gearing. 

 

 

Ah well, I know there are custom gearsets but I'm wondering any way to combine the C series trans to make a close ratio box?

 

Ah there's only so much you can do messing with stock gearing options. 

 

 

Yeah, but the 240 comes with a 4.083 diff (I have a vlsd and I am reasonably happy with it) I don't really want to change the diff because either I will get crappier mileage with better acceleration or vice versa. The only proper way it seems to me would be to shorten the 1-4 gears and get a taller 5th. I was thinking of going from stock gears to something different by pulling some gears out of older Z and 200sx transmissions. I was told I could use any of the gears from the FS platform transmissions as long as it is has W71 in the ID. I am not sure about the 71 but the W means the syncros are Bog Warner and should fit correctly. I got the info from here: http://www.s-chassis.com/forums/showthread.php?t=26164

 

What I want to do would look something like this:

 

STOCK:            Frankenstien:

1) 3.321            3.592 

2) 2.077            2.246 

3) 1.308            1.415

4) 1                   1

5) 0.759            0.745 <- here I would like to be somewhere from .65 to .67

 

 I am not completely sure about 1st or 2nd but I am pretty sure I will change 3rd. I already have a spare transmission, so I was thinking of doing a rebuild and seeing how things go. Worst comes to worst if it is not drivable I can change things back. but I don't think the changes are drastic enough to mess things up badly. I really just want to improve to 0-70 time. I don't know what your hp/tq numbers are in the zx but in the 240 with my KA I am making about 180 and have plans to bump that to 210-220 and hopefully have 190ish tq. This will be at the crank N/A. 3rd and 4th are ok for very tame driving but I dunno it seems to me if I am on it 3rd gear doesn't pull very hard at all.

 

That and of course the 5th gear, .67  is right around where I want to be and I think with the power I will have it there should be enough tq. So for this to work I would need the 81-83 280zx non turbo input/counter shaft ? Where did you get the 5th gear from? What year is that zx? I haven't seen anything that is .5333 in a 5th gear, unless I am misunderstanding something.

 

 

81-83 280zx non turbo input/counter 29/23= 1.261

5th gear 24/45(non-ZX) = .5333 *.1.261  = .672 Overdrive

 

 

 

 

 

Also dunno if it helps anyone: The FS5W71C came with the 200sx the FS5W71H came with the 240sx, as far as I know the only difference in those two transmissions is the bell housing to fit the different engine and the ratio of the 5th gear, which is 0.838 on the 200sx, otherwise they are internally the same.