Someone here, as I recall, changed their .82 OD gears to the .64 ratio. Not the trans, just the gears inside. I want to do the opposite. My big block, with a 245/235 @.050 cam just doesn't like to chug along at 1600-1800 at lower freeway speeds. I really need to be going at least 65 before it gets happy. I shoulda caught this before ordering, I just couldn't tell with the TH400 mitigating the motor's reluctance to run smoothly at lower RPMs.

I just don't need that tall of an overdrive, .82 sound better. I thought about 4:10 gears, which would kinda help, but that would change first gear too much.

Anyone have any details on swapping 5th gears?

Pbly me ...........Where were you when I wanted to swap my TKO 600 .82 for the .64 parts !!! ............ I bot the .64 mainshaft and gear to do the swap .........best thing to do is call Tremec Tech " Joe" gave me the details on how to do exactly .........they do have assembly info on their web site but it is genereic not specific to TKO been a while pretty sure it was JOE ........ BTW 28" tires and 4.30 rear gear with .82 is a little buzzy I bet you would be fine with 4.10 1st gear and 4.30 is a blast really not bad ....nice part is you can get lazy and pull away in 2nd no problem and I have a 250/262 cam

Trans parts are a lot more $$$ than a rear gear swap

I just swaped from a tremec with the .64 for a turbo 400 cause my 427 didnt like the lower RPM on the Hwy. I had 4.56 gears in the rear along with 28" tall tire and at 60 I was at 2100rpm. I would get detonation at that point with or with out vacuum advance. I think it would have been better with the .82 OD . It really liked it at 70 which was closer to 25-2600rpm.

I just swaped from a tremec with the .64 for a turbo 400 cause my 427 didnt like the lower RPM on the Hwy. I had 4.56 gears in the rear along with 28" tall tire and at 60 I was at 2100rpm. I would get detonation at that point with or with out vacuum advance. I think it would have been better with the .82 OD . It really liked it at 70 which was closer to 25-2600rpm.

Wow, 4.56's with that low TKO first gear? What was that like to drive? I have 28" rear tires, and thought 4:10 would be pretty low! Should I be messing with the rear instead?

Gibbons ........I think that's what I am trying to tell you .get on site with a good rpm calculator now that you know what rpm your motor likes and speed you want to drive do the math with either a 4.10 or 4.30 rear gear .........i run a 4.30 and other poster has 4.56 with 28" tires not too low IMO also makes 2nd gear a usable gear for take off in traffic etc ........... now if this a track car different story cause you may not want that much a overall 1st gear ratio for launches

i was sort of in this same boat a while back-i had a .8 tko, 3.73's
wish i had gotten the .6 and used 4.10's, felt like a bucking bronko in first, lol
as i remember, i talked to one of the suppliers, we decided it was better to sell it than the expense of trying to replace the gears
im back to a turbo 400 now, but loved the o/d gear, so im building a 4l80e this winter, lol

I just swaped from a tremec with the .64 for a turbo 400 cause my 427 didnt like the lower RPM on the Hwy. I had 4.56 gears in the rear along with 28" tall tire and at 60 I was at 2100rpm. I would get detonation at that point with or with out vacuum advance. I think it would have been better with the .82 OD . It really liked it at 70 which was closer to 25-2600rpm.

WOW, that's a lot of bucks making all thise changes:(:(:(

I find it a little odd that the 27 was having issues at 2100 rpm. I had a 427 in my 65 chevelle, 4.56 out back and a M20. I had a Crane solid lifter cam, roller rockers, Offy intake and a Holley 3 barrel carb, and it would pull from around 1500 in 4th gear all the way out with no spark knock.

Maybe I was just lucky:D:D:D

Someone here, as I recall, changed their .82 OD gears to the .64 ratio. Not the trans, just the gears inside. I want to do the opposite. My big block, with a 245/235 @.050 cam just doesn't like to chug along at 1600-1800 at lower freeway speeds. I really need to be going at least 65 before it gets happy. I shoulda caught this before ordering, I just couldn't tell with the TH400 mitigating the motor's reluctance to run smoothly at lower RPMs.

I just don't need that tall of an overdrive, .82 sound better. I thought about 4:10 gears, which would kinda help, but that would change first gear too much.

Anyone have any details on swapping 5th gears?
:yes:i swapped my gears out for the road-race kit that they offer for the tremec.
went from the .68 to the .82-OD and really like the results.
at the time i had 4.88 gears in the rear axle and the 427-wouldn't pull 5th gear below 60-mph which made it only good on the highway. it engine would still lope while pulling the car till it got up to about 80mph.
i think the swap cost about $795 for the parts + installation $$.
it involved swapping out the 3rd gear off the shaft (pressed on) and the output shaft, these were better steel for higher torque capacity also.
still running the same set-up today and real happy although the rear gears have gone up to a set of 3.73 and the engine has changed alittle.:thumbsup:

I would change rear end gears and get your cruise rpm where you want it. the resulting deep first gear ratio will be benificial if you ever want to take it to the strip (stick shifts really need DEEP first gear ratio's at the track), and while it may be pretty short in first, it really isnt bad.

Yeah, I am now looking at 4.10's instead of 3.73's. That will take me to 2000 rpm at 60mph. The motor is a little happier there.

!st gear wasnt bad at all with the 4.56 gears,,,

I really dont know why I was getting detonation in 5th gear under load at around 2100 RPM cruise but it happend with the 396 and 427 so Im at a loss why,,,,, I just know if I didnt use 5th everything was fine or if I was going 80MPH in 5th which I didnt like to do on the highway...

Yeah, I am now looking at 4.10's instead of 3.73's. That will take me to 2000 rpm at 60mph. The motor is a little happier there.
:boring:4.10-gears suck......look at 4.33, i think you would like these much better with your set-up:thumbsup:

I can't use 4.33's cuz I have a 3 series carrier, they only make 4.10's and 4.56's for that quantum jump. 4.56's sound pretty short... especially when my first is 2.87. What are rock crushers, 2.20? So guys with crushers and BB's who think 4.10's are too low would really poo-poo my final drive ratio. This car will never go to the dragstrip...

Gibb,

Whats the combo look like? My cam admittedly smaller, will go to 1100 rpms in 5th and not buck. This is with a .64 TKO, BB, and a 3.90 rear.