What's a good rear ratio?
07-20-2002, 08:52 PM
#1
Drifting
Thread Starter
What's a good rear ratio?
I'm trying to decide what to do to my driveline before I finish the L71 and reinstall the body. The car is a factory M21/4.11 car but I'm not looking forward to doing much street driving with the 4.11s. That gear is required to get any dig out of the crappy 2.20 first gear in the M21.
I recently started chatting with a local guy who is building wide ratio M22s with the new italian gear set. he'll take my numbers matching M21 and reconfigure it with the new gear set. With this set up I get a bullet-proof transmission with a 2.54 first gear. This could let me raise (numerically drop) the rear ratio to something a bit more livable. The dinal drive ratios of this transmission and a 3.55 rear are almost identical to the M21/4.11 combination, at least until you get to 4th, obviously. But I also have a good used 3.36 rear sitting here looking for a home, which is a lot easier than finding/building up a 3.55.
Here's the comparisons:
M21/4.11
1st 9.04
2nd 6.74
3rd 5.26
4th 4.11
M22w/3.55
1st 8.95
2nd 6.67
3rd 5.18
4th 3.55
M22w/3.36
1st 8.47
2nd 6.32
3rd 4.91
4th 3.36
I've toyed with the various extra gear transmissions like Richmond and Tremec, but with a solid lifter, rect port, tripower 427 I don't see highway cruising at 1800 rpm being real possible, not to mehtion the expense. I would have loved a Richmond 5 with a 3.08 rear but again, the expense is driving me back the other way and staying with 4 gears.
3.55 or 3.36... That is the question.
I recently started chatting with a local guy who is building wide ratio M22s with the new italian gear set. he'll take my numbers matching M21 and reconfigure it with the new gear set. With this set up I get a bullet-proof transmission with a 2.54 first gear. This could let me raise (numerically drop) the rear ratio to something a bit more livable. The dinal drive ratios of this transmission and a 3.55 rear are almost identical to the M21/4.11 combination, at least until you get to 4th, obviously. But I also have a good used 3.36 rear sitting here looking for a home, which is a lot easier than finding/building up a 3.55.
Here's the comparisons:
M21/4.11
1st 9.04
2nd 6.74
3rd 5.26
4th 4.11
M22w/3.55
1st 8.95
2nd 6.67
3rd 5.18
4th 3.55
M22w/3.36
1st 8.47
2nd 6.32
3rd 4.91
4th 3.36
I've toyed with the various extra gear transmissions like Richmond and Tremec, but with a solid lifter, rect port, tripower 427 I don't see highway cruising at 1800 rpm being real possible, not to mehtion the expense. I would have loved a Richmond 5 with a 3.08 rear but again, the expense is driving me back the other way and staying with 4 gears.
3.55 or 3.36... That is the question.
07-20-2002, 09:06 PM
#2
Team Owner
Re: What's a good rear ratio? (69L71)
I found up in Md. that my original 336 gearset was just OK, but not great for the short sprints on freeways....say an hour's trip to Pa.....but for cruising the freeways for longer than an hour....well, 3500-4 grand is a bit much on the engine...
far as I"m concerned...especially with a BB,....a 256/180/100/.60 would be a perfect tranny, and for the life of me I can't see why it wasn't that way from the factory some 35 years ago....
a silly 3 speed with an overdrive was the LOGICAL choice, what with growth of interstate highways and higher speeds....back in the days of US1 as our major N/S route, no overdrive was fine....only did 40-60 mph....
I went the 700r4 route, not a great tranny, barely acceptable...
GENE
far as I"m concerned...especially with a BB,....a 256/180/100/.60 would be a perfect tranny, and for the life of me I can't see why it wasn't that way from the factory some 35 years ago....
a silly 3 speed with an overdrive was the LOGICAL choice, what with growth of interstate highways and higher speeds....back in the days of US1 as our major N/S route, no overdrive was fine....only did 40-60 mph....
I went the 700r4 route, not a great tranny, barely acceptable...
GENE
07-21-2002, 12:51 AM
#3
Re: What's a good rear ratio? (69L71)
With my 3.36 rear end with 245 60 15 tires, I'm running around 2600 rpm at 60 mph and 3000 rpm at 70 mph. it not bad on the highway. These gears are bitchen for passing on the highway (55 mph highway). From 50 to 100 mph I love them.
However around town I wish for 4.11 for stop light to stop light, but I have an auto and you have a manual so that could be ok around town with a 3.36 gear.
If this is your highway car where your driving 70 or higher I would go with the 3.36
[Modified by Tominator, 10:51 PM 7/20/2002]
However around town I wish for 4.11 for stop light to stop light, but I have an auto and you have a manual so that could be ok around town with a 3.36 gear.
If this is your highway car where your driving 70 or higher I would go with the 3.36
[Modified by Tominator, 10:51 PM 7/20/2002]
07-21-2002, 01:11 AM
#6
Melting Slicks
Member Since: May 2002
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Re: What's a good rear ratio? (69L71)
Really, 3.55's are hard to come by? I think I have a set in mine, I can guess about 3300rpm at 70mph with the tach bouncing all over the place. The math seems to show this being about right.
[Modified by Schmucker, 11:11 PM 7/20/2002]
[Modified by Schmucker, 11:11 PM 7/20/2002]
07-21-2002, 01:58 PM
#7
Drifting
Thread Starter
Re: What's a good rear ratio? (Schmucker)
I didn't mean to say that 3.55s are hard to come by, just harder than bending over and picking up the 3.36 rear in front of me. I found a guy down in FL that sells rebuilt pumpkins very reasonably. I'm sure I can get a 3.55 from him.
I had 3.55s in my 350/350 convertible and it was a decent setup. Around town and short sprints were cake with the wide ratio M20. I drove the car from here in MD to my folks house on Long Island. 70 was right about 3200 RPM. It got a little annoying after a while but tolerable. Lets just say that I was being passed readily on the NJ Tpk. I didn't feel like buzzing 3600+ keeping up with traffic.
I had a 3.36 in my 71 LS5 coupe. It was an awesome cruiser for a non-OD car. I drove it home from Chicago and it was fine at 70 MPH. Tached right about 3K. That 454 had the torque to fry the tires even with the steep first gear. My 427 will be much more high strung so I don't know if I'll get the same dig as the 454. It will want to rev more.
The ideal setup for me is the Richmond 5 speed with the road race gearset and a 3.08 rear. The installation is cake and the gears give a reasonable compromise:
Trans Ratios
1st 3.04
2nd 2.13
3rd 1.57
4th 1.25
5th 1.00
Final Drive Ratios
1st 9.36
2nd 6.56
3rd 4.84
4th 3.85
5th 3.08
1st-4th are killer, even a little lower than the 4.11/M21 setup, but with a 3.08 rear I get the equivalent of a 20% OD! Unfortunately that setup will set me back about $2500. Plus the 3.08 rear!
Back in the day anything less that 3.70s were considered whimp gears. I guess we're all a little spoiled with today's modern OD cars. My 96 LT4 spins about 1800 RPM at 80MPH in 6th!
Decisions Decisions.....
[Modified by 69L71, 12:11 PM 7/21/2002]
I had 3.55s in my 350/350 convertible and it was a decent setup. Around town and short sprints were cake with the wide ratio M20. I drove the car from here in MD to my folks house on Long Island. 70 was right about 3200 RPM. It got a little annoying after a while but tolerable. Lets just say that I was being passed readily on the NJ Tpk. I didn't feel like buzzing 3600+ keeping up with traffic.
I had a 3.36 in my 71 LS5 coupe. It was an awesome cruiser for a non-OD car. I drove it home from Chicago and it was fine at 70 MPH. Tached right about 3K. That 454 had the torque to fry the tires even with the steep first gear. My 427 will be much more high strung so I don't know if I'll get the same dig as the 454. It will want to rev more.
The ideal setup for me is the Richmond 5 speed with the road race gearset and a 3.08 rear. The installation is cake and the gears give a reasonable compromise:
Trans Ratios
1st 3.04
2nd 2.13
3rd 1.57
4th 1.25
5th 1.00
Final Drive Ratios
1st 9.36
2nd 6.56
3rd 4.84
4th 3.85
5th 3.08
1st-4th are killer, even a little lower than the 4.11/M21 setup, but with a 3.08 rear I get the equivalent of a 20% OD! Unfortunately that setup will set me back about $2500. Plus the 3.08 rear!
Back in the day anything less that 3.70s were considered whimp gears. I guess we're all a little spoiled with today's modern OD cars. My 96 LT4 spins about 1800 RPM at 80MPH in 6th!
Decisions Decisions.....
[Modified by 69L71, 12:11 PM 7/21/2002]
07-21-2002, 03:12 PM
#8
Team Owner
Re: What's a good rear ratio? (69L71)
For a even 1/2 way reasonable stock BB Vette, with OEM rear suspensions....
that 3 something first gear in the 5 speed is nearly useless....driven on the street, it's 2-4 or even 5th every time....first gear will never get used, unless you hauling a horse trailer .....
My muncie with 336 and a SB L98 engine induction on an L48 stock fresh engine base was so strong that the 2.5 first gearset was about useless, so it was 2-4 all day long in driving traffic....
I say the gearset is useless even for dragracing in a near stock BB vette, as the only way it could ever be used is with sticky mickey...and then it a 1/2 shaft up your hiney every time....
IMO a 20% overdrive is not enough, period...gotta be at lease 30% and should be 40-50%.....to be effective, and fun....
course now I have a 700r4 auto, but stuck with original gearset, IF I could find a 308 setup for the right price....FREE, well, I"d switch....but that extra 10% is of no huge practical consequence either way, it's close enough...
now if I was stuck with a horrendous gearset...IE over 355, I"d have to switch at that point, pay for the privilage even....
GENE
that 3 something first gear in the 5 speed is nearly useless....driven on the street, it's 2-4 or even 5th every time....first gear will never get used, unless you hauling a horse trailer .....
My muncie with 336 and a SB L98 engine induction on an L48 stock fresh engine base was so strong that the 2.5 first gearset was about useless, so it was 2-4 all day long in driving traffic....
I say the gearset is useless even for dragracing in a near stock BB vette, as the only way it could ever be used is with sticky mickey...and then it a 1/2 shaft up your hiney every time....
IMO a 20% overdrive is not enough, period...gotta be at lease 30% and should be 40-50%.....to be effective, and fun....
course now I have a 700r4 auto, but stuck with original gearset, IF I could find a 308 setup for the right price....FREE, well, I"d switch....but that extra 10% is of no huge practical consequence either way, it's close enough...
now if I was stuck with a horrendous gearset...IE over 355, I"d have to switch at that point, pay for the privilage even....
GENE
07-21-2002, 04:15 PM
#9
Drifting
Thread Starter
Re: What's a good rear ratio? (mrvette)
It's not the 3-something first gear that's the problem. A 3.04 fisrt gear is fine with somthing like a 2.73 or a 3.08. The final drive ratio is around 9, which is near perfect, a little less with the 2.73s and a little more with the 3.08s.
The 3.04 fisrt gear with the 3.08s is almost identical to an M20 and a 3.70 rear. Its steep but there are guys here on the forum running that ratio. In fact, my old '90 5.0 mustang had a T-5 and a 3.08 rear with a 1st gear final ratio of 10.32! My LT4 has a 1st gear final of 9.25 so it's certainly not unheard of. Obviously for daily street cruising one could consider skipping 1st altogether, but with a BB that likes to run to 6500RPM I don't see a 9.36 being too big of a problem. I agree with you on the tire situation though. If I really want to get all that torque hooking up I'll have to use some DOT drag radials at the track. On the street I'd just have to watch how much foot I use in 1st. Most Richmond's have a 3.27 first gear and there are quite a few guys running them in both SB and BB cars.
All I need is the $$!
The 3.04 fisrt gear with the 3.08s is almost identical to an M20 and a 3.70 rear. Its steep but there are guys here on the forum running that ratio. In fact, my old '90 5.0 mustang had a T-5 and a 3.08 rear with a 1st gear final ratio of 10.32! My LT4 has a 1st gear final of 9.25 so it's certainly not unheard of. Obviously for daily street cruising one could consider skipping 1st altogether, but with a BB that likes to run to 6500RPM I don't see a 9.36 being too big of a problem. I agree with you on the tire situation though. If I really want to get all that torque hooking up I'll have to use some DOT drag radials at the track. On the street I'd just have to watch how much foot I use in 1st. Most Richmond's have a 3.27 first gear and there are quite a few guys running them in both SB and BB cars.
All I need is the $$!
07-21-2002, 07:17 PM
#10
Melting Slicks
Member Since: Feb 2001
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Re: What's a good rear ratio? (69L71)
Why not go with what you have for free? I have 3.36 and tach around 2800 @ 70 ... but I only have a 350/200 in the 72 ... if I want ground pounding rubber burning... I Z06 :crazy: :D :crazy: :D :crazy: :eek:
Actually... I've been thinking 3.08 for the 72 ... after all it is just a cruiser in all it's earned glory! Kinda like a great race horse put out to stud :lol: :lol: :lol:
Actually... I've been thinking 3.08 for the 72 ... after all it is just a cruiser in all it's earned glory! Kinda like a great race horse put out to stud :lol: :lol: :lol:
07-21-2002, 08:30 PM
#12
Racer
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Re: What's a good rear ratio? (69L71)
I see nothing wrong with the 4.11's out back. In the late 70's I had a '69 Z28 with the std. 4.11's and put 50K miles on it with the short little G60x15 tires. Those miles included a lot of 500 miles freeway runs. If you don't care that much about perfomance, go with the 3.36's you have. I would not bother with the gears in between and the extra expense.
