2014 6 SPD TX Baja - custom gearing... help please!

OK... so I've got a 2014 Baja with the TRD Supercharger... gobs of power and 5th and 6th gear are so close together it's pointless. I'm screaming over 3000 rpms over 75 MPH and sucking fuel down for no reason. With the extra power even first gear could be a touch lower and help acceleration to keep it in a fraction longer. With that said... is there an axle ratio swap that I could do to accomplish this? Is that a more viable option than having a custom 6th gear combo made for the RA60F trans?

Any insight would be most appreciative!

 

bigger tires.

 

I'd have to go much bigger to achieve the RMP drop I'm looking for in 6th... It'd look badass for sure, but I don't want a monster truck as my d/d...

 

i dont think i have heard anyone gearing down below the stock 3.73's

unfortunately as a 6 speed owner its something you are going to have to deal with, the lack of a decent OD gear.

 

With the power of the S/C... first gear seems taller than necessary as it is... It's not a rock crawler... at least not for my use... so dropping the axle ratios may be a solution, but where would I look to see how to go about it? Where would I get that done? I wouldn't want the rear locker effected, etc. I'm not a brilliant mathematician, how low would I need to go to drop 700 rpm @ 80 mph?

 

Changing the diff ratios will affect every gear and you'll probably miss your acceleration. However, I know the 6MT behaves almost like a 5AT switched to 4.10 gears. So if you went taller than 3.73 in the differentials it would be more like a 5AT I think. Never heard of wanting to undergear lol

 

Just re-read OP. If you get a custom gear do please post details. I'd love to see a fix for the 6MT

 

This. I was going to say there aren't add-a-gears for Tacomas but I didn't have enough knowledge on the topic so I left it

 

Chopper678, If you drove a s/c 6MT you'd happily take a smaller gear ratio... IMHO 6th gear should NEVER be your gear of choice for cruising 35/40 mph or above. 4th 5th and 6th gears are so close... as these are higher speed gears, with the current setup, 5th gear is basically unnecessary. 4th could be the 1:1 ratio (which is currently 5th) ... 5th could be the 6th (which is currently a 0.85 overdrive) and an ideal 6th would be much nicer overdrive in the 0.60 range.

That would be the ideal. I'd consider changing the rear axle ratio, but how low would I have to go to see 700 rpms lower @ 80 mph? (31.6 diameter stock tires for you number crunchers out there dying to help...)

 

I think it may be easier to give your current RPMs and desired RPMS (which would be Current - 700) rather than a drop. Whatever the percentage is (Desired/current) would be applied to your gear ratio.

Ex:
At 80MPH,

RPM_Current = 3000
RPM_Desired = 2300
(2300)/(3000) = .77

(Ratio_Desired)/(Ratio_Current) = .77


^That is stating that if you want 23% lower RPMS, you're going to have to get 23% taller ratios.

Rearranged to:
Ratio_Desired = (.77)*(Ratio_Current)
Ratio_Desired = (.77)*(3.73) = 2.857

That's SUPER tall! Someone correct me if I'm wrong

Can you tell me what you use your truck for? I'm sure there is a fair compromise other than changing your ratios. I highly dis-recommend that.

 

THANK YOU MATH MAN!!! Now... would the same logic apply to the 6th gear drive ratio? If I want to have a new 6th gear combo fabricated and the stock one is .85, for that 700 rpm drop what would that have to be assuming we stay with the stock 3.73 axle ratios?

 

Agreed. This was with 33's on the Autobahn, 5th gear.

 

(0.77)*(0.85) = 0.6517

That was just an example though. Still need your actual RPM at 80 MPH.

 

Based on the same 23% that would mean my 6th gear OD would need to be roughly .65 instead of the .85 it is currently... which is what I blindly figured without the math to back it. right?

 

http://www.grimmjeeper.com/gears.html Select RA60F with whatever size tires you have.

 

Fluffer... I'd have to modify the factory BAJA lift to go with 33" tires and cut wheel housings and ditch the flaps... not ready to do that but yes, that would work to a degree...

 

I think something is off. Look at the grimmjeeper link, you should be doing 86mph in 6th gear at 3000 with 265/70R16.

You don't have to trim much if you find a skinny 33. Even then, nobody but you will know if you do it right.

 

OK, so now it's all but decided... given that it would take a ridiculously tall axle ratio to accomplish the highway rpm / fuel economy issue and subsequently drastically effect the rest of the gears and capabilities... I'm back to finding a quality trans shop that fabricates and modifies trans gears reliably to customize the gearbox. Does anyone know if the RA60F has interchangeable gears on the shaft or if they are milled from a solid? I know the FJ RA61F trans is very similar but has a .73 6th gear... but my knowledge ends there... anyone know more???

 

Swap in the complete FJ trans and T-case, then you get manual shift capabilities out of the T-case as well. If you want better mileage buy a motorcycle.

 

Fluffer I'm pretty sure the tires are 265/75s... also... I've seen the skinny ones and just don't like that look... I'd have to go 285/75 to get the right "look" to go along with the bigger tire... I've seen it on 3" lifted trucks and they look badass, but just don't wanna go that big.