six speed tranny ?

66fasterback

New Member
Apr 2, 2003
36
0
0
I going to put a six speed in my 66 fastback. I'm going to need a overdrive gear. What is the best six speed tranny on the market. I have 411 rear gears about 500 hp. out of a paxton supercharge 289. I want a six speed and the best !
 
  • Sponsors (?)


May be a Little off base here but I think most 6 speeds 5th and 6th gears are both overdrives, Tremec t56 are for sure not sure about others, unless your wanting to turn about 1700 rpms at 65 I think a 5 speed may take care of your needs, of course a 6 speed is pretty cool
 
66fasterback said:
I going to put a six speed in my 66 fastback. I'm going to need a overdrive gear. What is the best six speed tranny on the market. I have 411 rear gears about 500 hp. out of a paxton supercharge 289. I want a six speed and the best !

i guess i'll give my 2cents. i think you really need to think over your combo and how you are going to driving it. if your running slicks , i can see the 4.11.
otherwise you got too much power for 4.11's. your first gear is going to be worthless. and the problem grows with 1st -5th(1:1). the reason it works for gp, i believe he is running 3.25 ratio and he's got way less power than you. 'm running 340fwhp, which is even less.
i run the t56, due to the 3.55 rear gears. 1st-4th(1:1). i already have traction problems on the street if you just dump the clutch. this problem wouldbe greater with the t5.as 1st and second probably would have to babied to get the power down. again gears play a role in this.
yes it is long legged. but i will say cruising on the freeway at 80, with the motor barely idling at 2100rpms is SWEEEET!! :D :D
a long way from the c4 with GV overdrive unit i had. even with that od, that combo ran 67mph at 2900rpms.
just a thought
i had to read my reply over....too much power :lol: :lol: :lol:
 
I have been talking to John at JMC Motorsports about his T56 kit which includes the crossmember and floor templets to allow the transmission to truely fit without being at a severe angle. The problem I have is that the tunnel comes up 1.5-2" and he says keeping my factory air is going to require some work.
Since I have a shop he is going to be setting me up as a dealer in the coming weeks once I get him all of the proper paperwork. Here is his number (619) 230-8824 and John is the man you what to talk. I dont want to get into which is the best but my way of thinking is that if it can hold up to the Viper's torque my blown 347 isnt going to stress it at all, and who can argue the coolness factor of a 6 speed? Hope this helps...
 
hhead & Shakin,

Are you guys running the .50 trans or the .62 (or is it .68?) ?
Are you guys using a scattershield or just the aluminum bell housing with a block plate?

My setup is 340 rwhp, 3.50 rear gears, 245/45-17 rear tires, and gear ratios:
1 3.27
2 2.13
3 1.57
4 1.23
5 1.00
6 0.76

In 6th 72 mph is ~2500 rpm

traction is a problem, but I'm working on a solution.
 
gp001 said:
hhead & Shakin,

Are you guys running the .50 trans or the .62 (or is it .68?) ?
Are you guys using a scattershield or just the aluminum bell housing with a block plate?

My setup is 340 rwhp, 3.50 rear gears, 245/45-17 rear tires, and gear ratios:
1 3.27
2 2.13
3 1.57
4 1.23
5 1.00
6 0.76

In 6th 72 mph is ~2500 rpm

traction is a problem, but I'm working on a solution.

i believe i am running the .62 6th. no scatter, alum bell, custom headers, r&p steering.3.55 gears. 245/45/17 tires. mine is a 67 coupe, so aside from the custom cross member, the tranny fit right in.
i believe the easiest solution is down in gear ratio with increase in power. with 500hp on tap i believe a 3.25 would be more livable.
 
So your 5th is .8 and your 6th is .62? How's the transition going back and forth from 4-5-6?
I'm going to be doing a little modding to hopefully stuff some bigger tires under the back end. One of my major concerns was to be able to use a scattershield. I've seen too many clutch failures. When I first started researching my swap there was a guy with a C5 vette that had a clutch failure and the clutch disc itself came all the way up into the dash area like a saw blade. I like my feet :nice:
 
gp001 said:
So your 5th is .8 and your 6th is .62? How's the transition going back and forth from 4-5-6?
I'm going to be doing a little modding to hopefully stuff some bigger tires under the back end. One of my major concerns was to be able to use a scattershield. I've seen too many clutch failures. When I first started researching my swap there was a guy with a C5 vette that had a clutch failure and the clutch disc itself came all the way up into the dash area like a saw blade. I like my feet :nice:
shifting up is no problem to 5th. sixth is way out there, i've got to be doing over 75 on the freeway to cruise 6th. but Vegas here I come!
on the downshift, if i'm in 5 or 6, then it is a two gear down shift. one gear doesn't do anything. on the 1-4,or4-1,it runs like normal.
i am having problem adjusting the clutch cable exactly to my liking. but one more adjust and I should be happy.
I did just get this running, i've got about 2000 miles on it so far since June. did i mention cruise control!! i'v got the hardware, just got to mount it.