Changing Gear Sets [Merged 11-7] transmission drive ratios

[90blacktsiawd]

I have the video of Devo tuning's evo 2 or 3 from Illinois going 8s in the quarter mile with a first gear that went all the way to 60 or 70

That sounds like a bit much T. I suppose what RPM he was shifting at has something to do with that but damn.

 

[pnishr]

yeah, if you use that speed vs gear vs RPM calculator in another thread (http://www.dsmtuners.com/forums/showthread.php?t=261093) , that 11% taller only increases your MPH by about 5MPH

49MPH at 9000rpm.
55MPH at 10000rpm.

You'd have to change your other ratios to get into the 60/70s with an 11% taller 1st.

maybe it was a Galant GSX with smaller final ratios...

I still want one anyway. That plus the TRE 10% taller 5th for UBER-top end. Just wish they still made the 25% taller one.

Below is using the 3.083* .89= new gear (2.743) method
Not sure if that is correct, or using the 3.083=1.11x (x=3.083/1.11=2.777) method is, but the higher speed is from using the smaller (2.743) method.


RPM 1st Gear vs 11% taller 1st Gear
500 2 3
600 3 3
700 3 4
800 4 4
900 4 5
1000 5 5
1100 5 6
1200 6 7
1300 6 7
1400 7 8
1500 7 8
1600 8 9
1700 8 9
1800 9 10
1900 9 10
2000 10 11
2100 10 11
2200 11 12
2300 11 13
2400 12 13
2500 12 14
2600 13 14
2700 13 15
2800 14 15
2900 14 16
3000 15 16
3100 15 17
3200 16 17
3300 16 18
3400 17 19
3500 17 19
3600 18 20
3700 18 20
3800 18 21
3900 19 21
4000 19 22
4100 20 22
4200 20 23
4300 21 24
4400 21 24
4500 22 25
4600 22 25
4700 23 26
4800 23 26
4900 24 27
5000 24 27
5100 25 28
5200 25 28
5300 26 29
5400 26 30
5500 27 30
5600 27 31
5700 28 31
5800 28 32
5900 29 32
6000 29 33
6100 30 33
6200 30 34
6300 31 34
6400 31 35
6500 32 36
6600 32 36
6700 33 37
6800 33 37
6900 34 38
7000 34 38
7100 35 39
7200 35 39
7300 36 40
7400 36 40
7500 36 41
7600 37 42
7700 37 42
7800 38 43
7900 38 43
8000 39 44
8100 39 44
8200 40 45
8300 40 45
8400 41 46
8500 41 46
8600 42 47
8700 42 48
8800 43 48
8900 43 49
9000 44 49

 

[1g4my2g]

I had my tranny built at TRE and I got the 11% taller 1st gear. Hopefully it will be worth it Anything to give me more time for the 1st to 2nd gear shift. 5mph may not seem like much, but every bit helps.

 

[pneumo]

AHA! I see the speed-in-gear calculator is becoming a useful tool.

The 11% taller first gear has other benefits. It may only give you an extra 5 mph at revlimit, but it raises the rpm where second gear begins by 600 rpm! Instead of getting into second at 4900rpm (44 mph) with stock 1st gear, now you drop into second at 5500rpm (49 mph).

Dammm I think I just talked myself into another mod.

 

[pnishr]

AHA! I see the speed-in-gear calculator is becoming a useful tool.

The 11% taller first gear has other benefits. It may only give you an extra 5 mph at revlimit, but it raises the rpm where second gear begins by 600 rpm! Instead of getting into second at 4900rpm (44 mph) with stock 1st gear, now you drop into second at 5500rpm (49 mph).

Dammm I think I just talked myself into another mod.

yeah ithat calc is pretty handy. As soon as I have a dyno-sheet, I'll be putting all the info in that thread to good use.

No, I see the value of the gear, especially for where it subsequently puts you in the RPMs on 2nd gear, I was just making the point that a car was NOT doing 60-70mph unless something else was drastically changed in the driveline. I didn't even know they made that 1st gear, but now that I do, I've got to get it too. In time...

 

[Morphius]

If you were to pull a gear from a tranny with 100K on the clock, you can literally see wearing differences on the teeth themselves between the first 3 mm and the last 11mm. This is directly due to the fact that there is a thin "green area" right behind the teeth.

The difference in wear pattern can be attributed to material, loading (manner in which the gear carries the load), and eccentricity of the gear to the shaft more so, than the amount of material behind the gear. Unless it's obscenly thin, you will see similiar wear on a gear with 3mm behind the teeth vs one with 6mm with everything else the same.

 

[99gst_racer]

The difference in wear pattern can be attributed to material, loading (manner in which the gear carries the load), and eccentricity of the gear to the shaft more so, than the amount of material behind the gear.

So, given that standpoint, if two different gears used for the same application are made of the same material and are loaded the same, then what attributes makes one stronger than the other?


PS: Just a little FYI; all of my information that I have shared in this thread came straight from Jon Ripple @ TRE.

 

[Morphius]

So, given that standpoint, if two different gears used for the same application are made of the same material and are loaded the same, then what attributes makes one stronger than the other?

Finish quality and attention to details to features that induce stress. (looking at the one gear, it appears to be poorly cut and has too small a radius at the root. ) Also, heat treatment is a BIG one.

My point was there would be other qualities of the gear that would attribute to the failure first.

PS: Just a little FYI; all of my information that I have shared in this thread came straight from Jon Ripple @ TRE.

Cool he's a good source.

My source was some engineers at GM's Gear center that have been designing/testing gears before Jon was born.

 

[Maglin]

I've seen the biggest reason for broken gears are improper alignment. Bearings start to wear and tooth contact starts to drop. Now instead of 90% of the teeth meshing it might go to 70%. And no matter how strong a gear is you can't just unload a motor on it. If the gear doesn't break the case will. You have to slip the clutch. I launch at 10 psi and by the time the clutch is fully disengaged I'm at 32 PSI and pushing the clutch back in for the 1-2 shift. People always have something to say about how my car looks to almost pull the front wheels off the ground when I launch.

The 4th gear is a lot smaller width wise and thus can not handle as much torque as the other gears. Hell I think 5th is wider but not to much. That is the reason it breaks most often in our cars.

Shep runs a dogbox. Only thing OEM is the case really. And it's modified to accept the gear set. Straight cut gears don't have the axial loading that heilicial (can't spell it) gears do. They are less prone to crack the case from to much torque and shock going through them. The axial loads will try to force the gears to move apart by pushing the shafts in opposite directions thus reducing tooth contact. Being that our cases are aluminum they will flex a little bit allowing this action to take place. Lots of contributing factors their to look at.

The taller 1st is a good idea if you have the money. If you have a large turbo you should definitely see some 60' improvement. People running small turbo's (18G or less) probably won't see to much of an improvement. The 1-2 shift quality will improve though. The reason turbo's would make a difference is large turbo's usually don't reach full spool in 1st gear stock, and if you do it's at the very end of 1st. Smaller turbo's will reach full spool in 1st a decent amount of time before shifting.

 

[jeharrisonjr]

I saw this on a car listed on ebay I cant seem to find anything about it. Can it be done? I would like to get 35-40mpg highway with my DSM.





Drive train is:
Under hood shifter bushings, Turbo 5 speed with 10% taller 5th gear for gas millage (wich is 35-40mpg highway) Fidanza Auminum flywheel, Centerforce DF clutch, SBR limited slip differential shimmed tighter for racing, BFG g-force 255/5016 Drag radials in front 205/55/16 new tires in back. Wheels are weld racing 16"x8" wheels (May not come with car) Also have stock swirlies & steelies all with good tires.

 

[kenamond]

Everything but the first line of this post belongs in the classifieds.

N/T can maybe get that mileage, but I think you'll have trouble with a turbo DSM. As I recall, changing 5th gear ratio in a FWD to the AWD ratio gives you lower RPM at cruising, ECU is closed loop and engine management is more efficient. But were you actually just trying to sell your car or find out about that eBay car?

 

[Littlebeeper]

he's just trying to show whats printed instead of trying to find the ad on E-bay. Read under Drivetrain. that's what his question is about. Again its a cut and past for us to see, he's not actually selling anything

 

[XSNRGGST]

Mr. Wiseman sir... I believe he was just posting the Ebay add he found. He was not trying to sell his own car or anyone else's. He was simply trying to find out if there is a taller 5th gear available to achieve better gas mileage.


Correct me and bannish me to Riceboy Tuners if I am wrong.

 

[roadrunner2176]

Awhile back I remember seeing taller 5th gear kits for dsms. The gears were straight cut so they would sound like you were in reverse. At the time this was more for a faster top speed than fuel consumption. The gearing would improve your fuel economy on the highway, amount depends on how hard you get on it. Your still using gears 1-4 before 5th gear; if you stay out of boost it might be possible.

As for the NT they can get between 35 and 45 mpg on the highway without changing any gears. With my daily driver I get a regular 42-44 mpg on the highway.

 

[jeharrisonjr]

Sorry everyone I was just copy and pasting what I saw on ebay so that you guys would not have to go look for it. I know a N/T can get this kind of gas mileage but the best I can get is 27mpg on the highway. Does anyone know where to get these 5th gear kits, I need to do a tranny rebuild anyway (please see my 2nd gear post)

 

[snox135]

TRE sells the 10% taller 5th gear.

 

[jeharrisonjr]

Thanks a lot I just sent a request for a price quote exchange

 

[kenamond]

Sorry guys!! I completely missed that!

 

[Defiant]

I seriously doubt you'd see that much mileage increase. You might get another 3MPG out of it. For one thing, he's FWD instead of AWD, so he both has a higher final drive and less parasitic drag.
I don't believe his claims for that mileage, either.

 

[jeharrisonjr]

If I wear going to be rebuilding my transmission should I put the 10% taller gear in anyway. IS it ok to use with my AWD? and is it going to be more like 15 to 20% taller because it is AWD?

 

[thekellbeast]

Jack's Transmissions has the 10% taller Evo3 gear too.

http://www.jackstransmissions.com/p...d=203&osCsid=687cc6c1291ff2304412bb922a904531

 

[95blackGsTurbo]

My TRE transmission has a taller 5th gear. At 80mph I only see 2600 rpm. Does nothing for the gas mileage. At that speed, the amount of throttle percent it takes to keep the car going that fast is more than if I was at 3200 because I am not in boost so the car is constantly on the gas. Used a scantool to show my throttle percent and at cruising it was 9% more throttle than with a stock one.

 

[BlackHawkAWD91]

I ran the TRE fifth gear and that 5th gear would tach 2900rpm@88-89mph. Best mpg i got was on south carolina to ohio road trips, i'd get about 30-31.

 

[polen]

my turbo DSM on highways get around 40 MPG. Turbo cars use less gas then NT when the turbo is not spooling. I drove 70 miles on a 1/8th a tank

 

[jeharrisonjr]

Is that with or without the taller 5th gear and I assume your car is FWD