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Topic Review (Newest First)
02-14-2019 02:51 PM
86chevyjoe Basic description of rig: 1972 Jeep CJ5

Engine: 2.3L Suzuki Aerio

Transmission: Samurai 5 speed

Transfer case(s): Samurai 6.5:1

R&P: 5.13

tire size: 34" swampers to 37" MTR's

Type of wheelin you do: PNW trails, snow

How you like it on the highway: too low geared, 55 mph is comfortable

How you like it offroad: good, but could be better

If you had to do it again whats gears would you buy: i'd do a vitara/tracker hydraulic 5 speed w/ tracker/vitara rangebox and 4.7 geared toyota case doubler - a gear for every scenario. I was either too low or too high w/ single sami case
02-11-2019 01:07 PM
Gwagensteve 4.88 R&P would correct the speedo with 33Ē tires. Can you give me an RPM at a GPS confirmed speed in 4th or 5th gear?
02-11-2019 04:53 AM
Zuk-E
Quote:
Originally Posted by Gwagensteve View Post
You're missing that the speedo drive can't see what's happen upstream of it, only downstream. For your example to be correct, the speedo would read differently in each gear.

The speedo is calibrated for rear end ratio and tire diameter. If you put reduction gears in the transfer case, the engine revs to achieve the same transfer output speed increase. If the car was running stock tyres and axle ratio, the speedo would still read correctly, the engine just has to rev higher to make the output shaft of the transfer spin at the same speed it did before.

If I change gear from 5th to 4th, revs jump up at the same output shaft speed, just like fitting transfer reduction gears, the speedo has no idea this has happened either.

So say now I put 31" tires on. These are bigger so for the same transfer output speed, the car travels 16% faster. The speed reads 50 MPH but the car is doing 58mph. I can gear the transfer case however I like, or put the car in whatever gear, when the speedo is reading 50MPH, the car is still actually going 58.

Transfer gears correct gearing with bigger tires - they do this by increasing engine speed at a given road speed, but the speedo can't see this. The speedo still thinks the car has 26" tires on it and a 3.7 rear end. Changing the axle ratio will effect the speedo reading, as will changing tyre size. They're the only two things that can change it.
This has been good fuel for thought and in thinking this thru, I see what you are saying. If Speedo sensor is on the RPM of the output shaft of the TC or the driveshaft, that RPM would be "hard coded" per say to the rear end ratio and tire diameter no matter what happens upstream as you said. So now I really don't understand why my speedo is +-1 MPH when compared to my GPS with 33" tires. One thing I've never checked is speed when in low range. I guess most of the time I'm in low range, I'm going so slow, it really doesn't even register.
02-09-2019 09:40 PM
Gwagensteve You do realise it's mechanically impossible for transfer gears to change the speedo reading, right? As I said, if changing transfer gears changed the speedo reading, then so would every gear change in the manual transmission.

Don't just assert what you saw on your vehicle, You haven't proved anything. Prove me wrong mechanically. The speedo drive is pressed onto the output shaft of the transfer and so is locked to tailshaft speed. Just think about that carefully when scripting your response.
02-09-2019 09:22 PM
supazuk94 Basic description of rig: Some tube tube and rust

Engine: 1.6 8v with 1.3 EFI, header 2" exhaust

Transmission: 1.6 tracker 5 speed

Transfer case(s): kicker 3 ( side kick doubler (stock gears) to samurai 5.14

R&P: toy 4:30

tire size: 39.5

Type of wheelin you do: rock and new england muck

How you like it on the highway: not in years trail rig

How you like it offroad: works good

If you had to do it again whats gears would you buy: will bee adding auto soon
02-09-2019 09:16 PM
supazuk94
Quote:
Originally Posted by Gwagensteve View Post
You're missing that the speedo drive can't see what's happen upstream of it, only downstream. For your example to be correct, the speedo would read differently in each gear.

The speedo is calibrated for rear end ratio and tire diameter. If you put reduction gears in the transfer case, the engine revs to achieve the same transfer output speed increase. If the car was running stock tyres and axle ratio, the speedo would still read correctly, the engine just has to rev higher to make the output shaft of the transfer spin at the same speed it did before.

If I change gear from 5th to 4th, revs jump up at the same output shaft speed, just like fitting transfer reduction gears, the speedo has no idea this has happened either.

So say now I put 31" tires on. These are bigger so for the same transfer output speed, the car travels 16% faster. The speed reads 50 MPH but the car is doing 58mph. I can gear the transfer case however I like, or put the car in whatever gear, when the speedo is reading 50MPH, the car is still actually going 58.

Transfer gears correct gearing with bigger tires - they do this by increasing engine speed at a given road speed, but the speedo can't see this. The speedo still thinks the car has 26" tires on it and a 3.7 rear end. Changing the axle ratio will effect the speedo reading, as will changing tyre size. They're the only two things that can change it.
only one correction in the Samaria the speedo DOES see difference in tcase gears i have done the change in GPS
02-09-2019 09:04 PM
supazuk94 great topic adding to FAQ
02-08-2019 02:05 PM
Gwagensteve You're missing that the speedo drive can't see what's happen upstream of it, only downstream. For your example to be correct, the speedo would read differently in each gear.

The speedo is calibrated for rear end ratio and tire diameter. If you put reduction gears in the transfer case, the engine revs to achieve the same transfer output speed increase. If the car was running stock tyres and axle ratio, the speedo would still read correctly, the engine just has to rev higher to make the output shaft of the transfer spin at the same speed it did before.

If I change gear from 5th to 4th, revs jump up at the same output shaft speed, just like fitting transfer reduction gears, the speedo has no idea this has happened either.

So say now I put 31" tires on. These are bigger so for the same transfer output speed, the car travels 16% faster. The speed reads 50 MPH but the car is doing 58mph. I can gear the transfer case however I like, or put the car in whatever gear, when the speedo is reading 50MPH, the car is still actually going 58.

Transfer gears correct gearing with bigger tires - they do this by increasing engine speed at a given road speed, but the speedo can't see this. The speedo still thinks the car has 26" tires on it and a 3.7 rear end. Changing the axle ratio will effect the speedo reading, as will changing tyre size. They're the only two things that can change it.
02-08-2019 12:36 PM
Zuk-E
Quote:
Originally Posted by Gwagensteve View Post
The speedo drive is on the output of the transfer case that means itís unaffected by anything upstream of the speedo drive- what gear the gearbox is in, what range the transfer is in, or transfer case reduction.

Itís only affected by whatís downstream of the speedo drive- axle ratio and tyre size.

Put bigger tyres on and the speedo becomes inaccurate. Change the axle ratio and speedo becomes inaccurate. Put the transfer case in low range and the speedo doesnít become inaccurate.

I canít explain it any more clearly.
I guess I just cannot wrap my head around this. If it's on the output of the transfer case, then putting lower gears in the case will slow the rotation of the output shaft. That should cause the speedo to read faster than you are actually going if all else is stock. Adding a larger diameter tire without changing transfer case gears would cause the speedo to read slower than actual speed is all else is stock. But if I slow the output shaft with TC gears AND increase the tire diameter with 33" vs 27" stock to go further on 1 revolution of the tires, they counter-act and I get a closer to accurate speedo reading. What part am I missing?
02-06-2019 10:50 PM
Gwagensteve The speedo drive is on the output of the transfer case that means itís unaffected by anything upstream of the speedo drive- what gear the gearbox is in, what range the transfer is in, or transfer case reduction.

Itís only affected by whatís downstream of the speedo drive- axle ratio and tyre size.

Put bigger tyres on and the speedo becomes inaccurate. Change the axle ratio and speedo becomes inaccurate. Put the transfer case in low range and the speedo doesnít become inaccurate.

I canít explain it any more clearly.
02-06-2019 07:32 AM
Zuk-E
Quote:
Originally Posted by Gwagensteve View Post
The speedometer doesnít know what gear you are in. Just the same way the speedo doesnít change its reading when you change gears in the gearbox or change ranges in the transfer case, it doesnít know that there are reduction gears in the transfer case. It took me a while to work this out myself. Yes, it corrects revs at road speed, but NOT the speedometer, because itís downstream of the reduction.
So where is the speed sensor and what does it use to pick up the speed? I would think it measures the rotation of the drive system either in the tranny or transfer case or tire rotation in the axle. I doubt it's in the axle as I don't see anything there. My thought was if it's using rotation somewhere within the driveline, a larger tire would cause the speedo to read low but that is offset by a lower gearing. This is an interesting topic as I am learning something new.
02-04-2019 03:05 PM
Gwagensteve The speedometer doesnít know what gear you are in. Just the same way the speedo doesnít change its reading when you change gears in the gearbox or change ranges in the transfer case, it doesnít know that there are reduction gears in the transfer case. It took me a while to work this out myself. Yes, it corrects revs at road speed, but NOT the speedometer, because itís downstream of the reduction.
02-04-2019 05:00 AM
Zuk-E
Quote:
Originally Posted by Gwagensteve View Post
That doesn't make any sense - transfer case gears have no effect on the speedometer accuracy, that's a function of axle gears and tire diameter.
I don't know then but I have a GPS installed and when in high range, it's pretty accurate. I guess I just figured that lowering the TC gearing slightly (18%) in high range and adding tire diameter just happened to even out.
02-03-2019 09:57 PM
YotaAtieToo
Quote:
Originally Posted by 2big bronco View Post
The lower the t case gears the lower the high range, so yes it would effect your speedometer the same way different gears in the axle will.
Except that the speedo reads off the rear out put, so any gear change before that won't affect it, only after.
02-03-2019 07:14 PM
2big bronco
Quote:
Originally Posted by Gwagensteve View Post
That doesn't make any sense - transfer case gears have no effect on the speedometer accuracy, that's a function of axle gears and tire diameter.
The lower the t case gears the lower the high range, so yes it would effect your speedometer the same way different gears in the axle will.
02-02-2019 06:39 PM
Gwagensteve That doesn't make any sense - transfer case gears have no effect on the speedometer accuracy, that's a function of axle gears and tire diameter.
02-01-2019 07:59 AM
Zuk-E Basic description of rig: Stock '87 Samurai with SPOA and TC Gears

Engine: Stock

Transmission: Stock

Transfer case(s): 5.14:1 Calmini

R&P: Stock

tire size: 33x10.50

Type of wheelin you do: trails, rocks

How you like it on the highway: In high range, speedo is almost right on

How you like it offroad: low range is low.

If you had to do it again whats gears would you buy: Only con I have with these TC gears is that they are noisy. They whine. It's a common issue with Calmini at least it was 15 years ago when I got them.
02-01-2019 04:24 AM
DannyK Basic description of rig: Stockish Samurai on YJ's springs SPUA

Engine: 1.6 16v

Transmission: Stock Samurai 5 spd

Transfer case(s): 6.5:1

R&P: Stock 3.73

tire size: 34" LTB's

Type of wheelin you do: Typical east coast trails

How you like it on the highway: Great

How you like it offroad: Great

If you had to do it again whats gears would you buy: Same 6.5:1
01-25-2019 09:19 PM
YotaAtieToo
Quote:
Originally Posted by 2big bronco View Post
I would buy the $200 hoopty sidekick from 2bb and install the 2.0 in my/your samurai with your 3spd. Then with all the extra power and the auto realize you dont really need a standard low range and just run the trackick case that came with it combined with 3.0 gears
All sounds good except I don't have a Sami it's a soft top 2 door tracker factory 8v/3apd/4x4

I don't see the 3.0 gears being worth the money, just not enough of a jump. I think the Sami case with 4.16 or 4.9s would be sweet. I don't need to go more the 45 mph, so 1.6 high with 4.63s or 5.13s and 31-32s should be good, then low range should be pretty good with the auto and light weight. The only problem is Sami cases are getting hard to find. I had 2 stashed for a reason, but they're gone

Might just do the 4.24s and the 5.13s since they're drop in. Or a doubler to a Toyota case then I'd have 1.8/2.28/4.1 with the ability to gear either case.
01-25-2019 08:56 PM
2big bronco I would buy the $200 hoopty sidekick from 2bb and install the 2.0 in my/your samurai with your 3spd. Then with all the extra power and the auto realize you dont really need a standard low range and just run the trackick case that came with it combined with 3.0 gears
01-25-2019 02:51 PM
Gwagensteve Basic description of rig: '83 SJ410T, 4 link/radius arm 100" WB, Suzuki based axles, too heavy.

Engine:G16B

Transmission:AW-4

Transfer case(s): 6.4TT gears, TT Twisted T shift rails

R&P: 5.13 (more on that in a minute)

tire size:35

Type of wheelin you do: Technical trails

How you like it on the highway: It's a tiny bit too low geared - 3700rpm at 62MPH

How you like it offroad: Too low.

If you had to do it again whats gears would you buy: I'd stay with the 6.4's, but run taller R&P. I'm swapping in 4.6 now which will drop me to 3330 on the highway and loosen the converter up off road a little. At the moment the converter basically won't slip off road.

Photo of vehicle for reference.



Currently also taking weight out and lowering it.
01-23-2019 07:46 AM
Diesel_Zuk Basic description of rig: Samurai, diesel swapped, stretched 18", steel flatbed, lot heavier than stock.

Engine: 1.9 TDI

Transmission: Geo tracker 5 speed

Transfer case(s): Geo tracker, twin sticks, 4.24 gears, slip yoke eliminators.

R&P: 3.73

tire size: 33x12.5x15, worn out, actual measurement currently, 31.25"

Type of wheelin you do: Rocks, mild trails, Moab, other Utah wheeling, etc.

How you like it on the highway: high range is too high with the 3.73's and 33's, I went with the tracker tcase to try to lower my high range RPM's at high way speeds, but it's just quite a bit too low.

How you like it offroad: Does good offroad, climbs easily without much if any throttle.

If you had to do it again whats gears would you buy: I'm planning on swapping in 5.13 gears in the very near future, in order to be able to daily it a little better.
01-22-2019 09:40 PM
YotaAtieToo Bump
01-20-2018 10:30 AM
xjtony Basic description of rig: 88 Samurai, toy axles, shackle reversal, 38.5 boggers, toy rear leafs in back and RE 1.5Ē yj leafs up front. Yota ifs steering box with tc pump. 1310 driveshafts.

Engine: rebuilt 1.3 with crappy Weber and header/flowmaster

Transmission: stock 5spd

Transfer case(s): 6.5 trail gear gears installed

R&P: 5.29 yota axles

tire size: 38.5x13.50r15 Boggers

Type of wheelin you do: trail/mud

How you like it on the highway: n/a

How you like it offroad: works okay I guess

If you had to do it again whats gears would you buy: I would not have geared the case so low. I think the 4.9 tcase Gear would have been better for the southeast wheeling I do, mainly dirt/mud. But for rocks and obstacles the 6.5 case is where itís at.
12-24-2017 06:34 PM
89lc Basic description of rig: 86 Sami, 3-link front and rear, toy axles, internal cage, and most of the basic stuff for a wheeling rig.

Engine: 1.6 16v

Transmission: Sami 5spd

Transfer case(s): Sami with 6.5:1 gears

R&P: 5.29 f&r with a spool in the rear and Detroit in the front.

tire size: q78-16 TSL's

Type of wheelin you do: Mostly clay hills and dirt with some rocks occasionally

How you like it on the highway: Sucks, full hydro and at 55 mph I'm running 3200 rpm.

How you like it offroad: Amazing so far, but I haven't had much time to wheel it lately.

If you had to do it again whats gears would you buy: I would probably go with a 4.9 gear set or swap the trans t-case out for a 4 spd auto and D300 with 4:1 gears.
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