Team Camaro Tech banner

1 - 20 of 27 Posts

·
Registered
Joined
·
341 Posts
Discussion Starter #1
I currently have 4.11 gears and a locker in the rear end. Planning to go with a Trutrac and new 30 spline axles. I have a later model 8.5" 10 bolt.

I have a 26.5" tall tire currently but will be changing to 25.5". Anyone have experience with 3.42 and 4 speed in a first gen? I've got a BPE 355 making peak hp a little over 400hp. A really can't cruise at more than 60 with the current setup so I'd like some improvement there without being completely slow off the line. Hard to really say what off the line performance is now because the smallest amount of aggression at launch just spins the tires I currently have.

I know this has probably been discussed a ton but looking for feedback in a similar setup.
 

·
Premium Member
Joined
·
3,387 Posts
What is 1st gear in your tranny?
Muncie M20 has a 2.54 1st and M21 & M22 have 2.20.
 

·
Premium Member
68 Camaro SS/RS clone, 454 BB 4 speed, 3.73 Posi, new paint, motor, trans and diff assembly. 2" Drop
Joined
·
141 Posts
I am scribing to this. I have 3:73 with 4 speed and 255/60-15's. Im not sure what trans I have, either a wide or close ratio M20 or M21, but told the only way to tell is by the grooves in the input shaft.
:unsure:
 

·
Registered
Joined
·
630 Posts
While I don't know the difference in our transmissions first gear, I can say this. I have 215/70 R15 (charts says 25.9 tall) tire.

I went the opposite direction recently from 3.08:1 to 3.55:1. While I am fine with my choice I know I would not have been unhappy with the 3.42:1.

I don't know if that helps you at all, but it's my take on it drawing from my experience.
 

·
Premium Member
Joined
·
3,646 Posts
4:10 to 3:42 is a big jump. I recommend an overdrive . Best of both worlds. Tremic or gear vendor. I definitely like my Tremic.
 

·
Registered
Joined
·
1,843 Posts
OP

enter your 411 in a RPM calculator to see what RPM's at what speed will be acceptable to you

 

·
Moderator
Joined
·
13,976 Posts
Cruising at 60 it doesn't matter what your 1st gear ratio is. Final is still 1:1

26.5" tire with 4.11 is 3130 @ 60 mph
25.5" tire with 3.42 is 2700 @ 60 mph

That said who drives 60. Need to look a 70 mph to get a better picture as i see it.

26.5" tire with 4.11 is 3650 @ 70 mph
25.5" tire with 3.42 is 3150 @ 70 mph

I would go with 3.31 2600 @ 60 mph 3000 @ 70
 
  • Like
Reactions: bills69

·
Premium Member
Joined
·
1,035 Posts
3.73's with an overdrive! I know...money...
 

·
Registered
Joined
·
341 Posts
Discussion Starter #10
I’ve done all the RPM calculators seven ways from Sunday so I know what I’ll be doing in 4th. I’m more curious about how it will be off the line with the 3.42s.

Yeah, overdrive would be great and I do plan to get their eventually but not in the near term. The TKO500 looks like it would pair nicely with the 3.42s.
 

·
Moderator
Joined
·
13,976 Posts
TKO 600 works better with 3.55 and 3.73
 
  • Like
Reactions: StevieBB54

·
Registered
Joined
·
11 Posts
I currently have 4.11 gears and a locker in the rear end. Planning to go with a Trutrac and new 30 spline axles. I have a later model 8.5" 10 bolt.

I have a 26.5" tall tire currently but will be changing to 25.5". Anyone have experience with 3.42 and 4 speed in a first gen? I've got a BPE 355 making peak hp a little over 400hp. A really can't cruise at more than 60 with the current setup so I'd like some improvement there without being completely slow off the line. Hard to really say what off the line performance is now because the smallest amount of aggression at launch just spins the tires I currently have.

I know this has probably been discussed a ton but looking for feedback in a similar setup.
I recently installed a Tremec TKO600 in my 69 Z with 3.73 gears. Guy at SST said that with 3.73 gears, 1st gear would be like having a 4.56 set in the back. Great set up for cruising but the TKO600 won't shift above 7000rpm.
 

·
Premium Member
Joined
·
3,646 Posts
In my opinion you will probably not be able to tell the difference between a 3.42 and a 3.55 by driving the car. I would expect that's why you can't find a 3.55. 3.42 is an "ok" gear and was stick in many second gen Camaro's and Firebirds. You will definitely be taking a step back if you enjoy the seat of the pants drive you have now. It will be like putting a block of wood under your gas pedal. You will be wanting more. If you're considering overdrive, I would just wait till then. Probably not what you want to hear though.
 
  • Like
Reactions: thesanz

·
Premium Member
Joined
·
1,902 Posts

·
Registered
Joined
·
341 Posts
Discussion Starter #16
In my opinion you will probably not be able to tell the difference between a 3.42 and a 3.55 by driving the car. I would expect that's why you can't find a 3.55. 3.42 is an "ok" gear and was stick in many second gen Camaro's and Firebirds. You will definitely be taking a step back if you enjoy the seat of the pants drive you have now. It will be like putting a block of wood under your gas pedal. You will be wanting more. If you're considering overdrive, I would just wait till then. Probably not what you want to hear though.
Thanks but waiting is not really an option. It has a locker currently which is a major pain in the butt on the street and at times can get twitchy in corners under power or if I hit a slick spot. Its gotta go. I guess I could just keep the gears I have for now but that pretty much means I stay under 60 or for extended drives at highway speeds. I know it will impact off the line performance, but I've just been trying to get an idea of how much it will impact it which I know is pretty hard to gauge on a message board. All out straight line acceleration is not and overriding priority so I am OK giving up some.
 

·
Registered
Joined
·
341 Posts
Discussion Starter #17
I recently installed a Tremec TKO600 in my 69 Z with 3.73 gears. Guy at SST said that with 3.73 gears, 1st gear would be like having a 4.56 set in the back. Great set up for cruising but the TKO600 won't shift above 7000rpm.
My first gear is already very low so no desire at all to go lower and I will never rev this engine anywhere near 7K. I did some playing with Tremec's calculator and felt the ratios of the TKO500 looked good with the 3.42 for what I want. But, overdrive is way down the road for me. AC, upgraded rear suspension, upgraded brakes and new wheels and tires all likely come first.
 

·
Premium Member
Joined
·
3,646 Posts
I understand getting rid of the locker for the street. My car with the TKO 600 does around 2500 RPMs at 80 MPH. If that helps any. I don't think you would be happy with a 3.42. your call, and your choice. I have had 3.42 gears in second generation Camaro's. I went up in all of them. They all had T350's. Good luck with what you choose.🤞
 

·
Registered
67 Camaro L78 M20 Convertible
Joined
·
95 Posts
I got a 3.42 with M20 in my 67 396/375 with 255/60 R15 BFGs.. or rather: had.. dropped a valve, awaiting new engine now.

I liked the ratio, but even for me its on the edge regarding tolerating it for longer drives around 70mph. And i only got a 2.5 dual exhaust.

Ortherwise i had a Big block, offering more fuller torque curve probably, it really pulled.

On the other hand it was tough to break loose the traction and spin the tires, i really had to do it correctly to do burn outs.

I will do a TKO600 Swap one day.. and then its the perfect gear, with 2.87 vs. 2.52 first gear difference..

Do what you feel like is more important to you. A little more off the line kick or better cruising..
 

·
Registered
Joined
·
2,892 Posts
I changed from 4:11 to 3:42 in my 454, 4 speed and 245/60/14 and made a big difference. Since I drive more in the 45-75 MPH range it makes sense for me. If I had to do it over, I would have gone with 3:31. Off the line the car is out of control at that with the amount of HP.
 
1 - 20 of 27 Posts
Top