Dual Trutracs and Yukon Gears Review
#25
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thanks for the speedy reply ZUK, re TT installation. all: i see ZUKs quote as being confidential until i contract with him and the job is complete, but let me assure you that it seems more than fair, and certainly less money than i have time or skills to complete the job.
now i am only left to consider whether i am going to gear down as well as install the TT. obviously this would be the time to do it, just need to jiggle it around in my brain some more. i am riding 31" tires on my daily driver/expedition vehicle, and i may never feel like going to 33". so i need to decide whether to bump down to 4.56s or just keep rolling my 4.10s. complicating factor: i have a R151F and xfer case from a turbo truck, which i will install someday, but probably not any time soon. so when i do, i will have slightly more gearing on 1st and 2nd... complicates the 4.56 question for me. any thoughts? much appreciated.
now i am only left to consider whether i am going to gear down as well as install the TT. obviously this would be the time to do it, just need to jiggle it around in my brain some more. i am riding 31" tires on my daily driver/expedition vehicle, and i may never feel like going to 33". so i need to decide whether to bump down to 4.56s or just keep rolling my 4.10s. complicating factor: i have a R151F and xfer case from a turbo truck, which i will install someday, but probably not any time soon. so when i do, i will have slightly more gearing on 1st and 2nd... complicates the 4.56 question for me. any thoughts? much appreciated.
#27
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i just did the calcs for gears and TTs for front and back. i think this will be a great set up for me, but it will cost me nearly 5 times as much to do it, versus just a TT in the front. I am thinking of sticking to installing the front TT during this seal replacement job. in the mean time i will dream of taking it to the next stage next time...
Last edited by bktaco; 09-25-2008 at 06:39 PM.
#29
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i am pulling the axles out to do the seals now, and i can afford a TT in the front. I will have to spend the extra $200 down the road, i just cant manage the nearly 2G for the whole job right now. by then i might have re-decided on a toy elocker anyway...
Last edited by bktaco; 09-25-2008 at 09:09 PM.
#30
Stuck 33x12.50s on last night with black steel wheels. TTs and 5:29's going in both front and rear this weekend pending UPS gets them here today and the mechanic!
Doing rogers 2" bl and BJ spacers soon as well as fj 80 coils!
Doing rogers 2" bl and BJ spacers soon as well as fj 80 coils!
#31
Its not just a matter of giving 10% more perceived power (I know this is not true from a physics point of view). You also bring the engine back into its torque band.
Last edited by Matt16; 09-26-2008 at 08:52 AM.
#32
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I did this a couple months ago. I was amazed- the difference was profound. Its a one gear difference on hills and it always feels like there's a perfect gear for the incline now.
Its not just a matter of giving 10% more perceived power (I know this is not true from a physics point of view). You also bring the engine back into its torque band.
Its not just a matter of giving 10% more perceived power (I know this is not true from a physics point of view). You also bring the engine back into its torque band.
also, what is your rpm at 60 mph? i know, i can work up a table, but just looking for a quickie estimate. thanks again.
#33
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Part numbers for TT
86 yota, ewong, tc:
Do you fellas have part numbers for the front and rear TTs? If you can provide these, please specify IFS or SFA. My truck is 85 4runner with SFA. It seems that I've seen a couple different part numbers for the front:
913A609 (two pinion) $436 rearendparts.com
913A612 (four pinion) $436 rearendparts.com
913A318 (?) $385?! performanceoffroadcenter.com
confusion. hoping to sort it out soon, and giter done before the snow starts flyin. thanks a million in advance
Do you fellas have part numbers for the front and rear TTs? If you can provide these, please specify IFS or SFA. My truck is 85 4runner with SFA. It seems that I've seen a couple different part numbers for the front:
913A609 (two pinion) $436 rearendparts.com
913A612 (four pinion) $436 rearendparts.com
913A318 (?) $385?! performanceoffroadcenter.com
confusion. hoping to sort it out soon, and giter done before the snow starts flyin. thanks a million in advance
Last edited by bktaco; 09-26-2008 at 09:20 AM.
#35
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bktaco - front and rear thirdmembers are interchangeable on your '85 - should be the same part number unless they have a "loose" one for front application... Even if they did, I would get the tight one - it's still not tight enough IMHO.
As for the effect of the gearing difference - I would say you notice it MORE on the highway because it brings your RPM into the engine's powerband. Each step in gear (say 4.30 to 4.56 or 4.56 to 4.88) will increase the RPM on the highway by about 200. So, you go from being just out of the powerband to just in the band. It's not like you go from lugging it to tached out!
As for the effect of the gearing difference - I would say you notice it MORE on the highway because it brings your RPM into the engine's powerband. Each step in gear (say 4.30 to 4.56 or 4.56 to 4.88) will increase the RPM on the highway by about 200. So, you go from being just out of the powerband to just in the band. It's not like you go from lugging it to tached out!
#37
so you are saying that you get the gearing benefit at the high end (freeway) as well as the low end (take off)? either one more than the other?
also, what is your rpm at 60 miles per hour? i know, i can work up a table, but just looking for a quickie estimate. thanks again.
also, what is your rpm at 60 miles per hour? i know, i can work up a table, but just looking for a quickie estimate. thanks again.
The speedo take off is at the T-case output, so whether you have 3.90 or 5.71 gears, 27 or 38" tires, your speedometer is still going to read X rpm at Y speed. At the speed everyone else usually does on the highway (65mph?), the engine is quiet comfortable and still has lots of pickup. Fuel economy went up in the city and is about the same on the highway.
#38
so you are saying that you get the gearing benefit at the high end (freeway) as well as the low end (take off)? either one more than the other?
also, what is your rpm at 60 miles per hour? i know, i can work up a table, but just looking for a quickie estimate. thanks again.
also, what is your rpm at 60 miles per hour? i know, i can work up a table, but just looking for a quickie estimate. thanks again.
The speedo take off is at the T-case output, so whether you have 3.90 or 5.71 gears, 27 or 38" tires, your speedometer is still going to read X rpm at Y speed. At the speed everyone else usually does on the highway (65mph?), the engine is quiet comfortable and still has lots of pickup. Fuel economy went up in the city and is about the same on the highway, but the fuel economy changes weren't as drastic as I thought at the start. I recently came out at 17mpg mixed, lots of big hill (I live on a mountain), short trips, and stop and go.
#39
Contributing Member
The speedo take off is at the T-case output, so whether you have 3.90 or 5.71 gears, 27 or 38" tires, your speedometer is still going to read X rpm at Y speed. At the speed everyone else usually does on the highway (65mph?), the engine is quiet comfortable and still has lots of pickup. Fuel economy went up in the city and is about the same on the highway, but the fuel economy changes weren't as drastic as I thought at the start. I recently came out at 17mpg mixed, lots of big hill (I live on a mountain), short trips, and stop and go.
Since the truck travels a different distance for each revolution read at the tcase, the speed indicated on the speedo can be wildly inaccurate.
#40
Fact:
The speedo cable is spun by a gear on the output of the T case, thus the speedo measures prop shaft speed, and calculates a speed it thinks you're going.
Fact:
The speedo does not measure ground speed.
Fact:
The speedo is going to read X speed, at Y rpm, in Z gear no matter what size your tires are or what diff ratio you have as its all downstream.
Fact:
From the factory, the speedo must read somewhere between 6% and 10% (not certain on those figures) faster than the actual speed. This is required by all manufacturers. It must certainly not under-read.
What's your beef with that? Where's the flaw in my knowledge, if there is one, I'd like to correct it.
Last edited by Matt16; 10-04-2008 at 12:36 PM.