optimal ratio?
04-24-2009, 06:23 PM
#1
Junior Member
Thread Starter
Join Date: Dec 2008
Location: Mesa, Az
Posts: 68
Likes: 0
Received 0 Likes
on
0 Posts
Car: 91 Z28
Engine: 305 TPI
Transmission: 5 speed
Axle/Gears: 3.23 posi
optimal ratio?
right now i have a 5 speed with a 3.08 posi. hopefully in the close future i am going to swap a t56 and build a new rearend. i am looking for feed back on what ratio to build the new one at. i was thinking 3.73's but i am worried about my top end. i have heard that the t56 pretty much takes care of all that but for a better all around deal, should i go with 3.42's instead?
04-24-2009, 07:07 PM
#2
Senior Member
iTrader: (2)
Join Date: Aug 1999
Location: Elkton MD, USA
Posts: 858
Likes: 0
Received 5 Likes
on
3 Posts
Car: 1985 Camaro Z28, VIN F
Engine: 427 sbc, HSR
Transmission: T-56, self rebuilt 700+ hp
Axle/Gears: Moser 12bolt, 3.42 trutrac
Re: optimal ratio?
Depends on your expected use, car weight, engine power.
For decent all-around setup, the 3.73s are the best IMHO. I need to hit 150mph in 4th gear, under 7000rpms, so I put 3.42s behind my T56.
For decent all-around setup, the 3.73s are the best IMHO. I need to hit 150mph in 4th gear, under 7000rpms, so I put 3.42s behind my T56.
04-25-2009, 07:17 PM
#4
Junior Member
Thread Starter
Join Date: Dec 2008
Location: Mesa, Az
Posts: 68
Likes: 0
Received 0 Likes
on
0 Posts
Car: 91 Z28
Engine: 305 TPI
Transmission: 5 speed
Axle/Gears: 3.23 posi
Re: optimal ratio?
i want the car for an everyday driver but some what of a sleeper. im looking for best all around performance. the engine im going to be putting in will be just over 300 hp. as for cam specs, for now im planning on a stock 350 cam out of a 91 350
this site has the specs
http://www.gmtips.com/3rd-degree/dox/tips/cams/cams.htm
this site has the specs
http://www.gmtips.com/3rd-degree/dox/tips/cams/cams.htm
Last edited by squatingeagle; 04-25-2009 at 07:21 PM.
04-25-2009, 11:47 PM
#5
On Probation
Join Date: Oct 2008
Location: Northern Utah
Posts: 6,319
Likes: 0
Received 17 Likes
on
17 Posts
Car: seeking '90.5-'92 'bird hardtop
Engine: several
Transmission: none
Axle/Gears: none
Re: optimal ratio?
There are a few different versions of the T56, ratios-wise. If you're using the '94-'02 version with the 2.66/1.78/1.30/1.00/0.74/0.50 gears, I suggest at least a 3.73:1. If you're using the version intended to be retrofitted into our third-gens, with the 2.97/1.94/1.35/1.00/0.84/0.62 gears, then either 3.42:1 or 3.73:1 would be fine.
04-26-2009, 03:49 PM
#6
Junior Member
Thread Starter
Join Date: Dec 2008
Location: Mesa, Az
Posts: 68
Likes: 0
Received 0 Likes
on
0 Posts
Car: 91 Z28
Engine: 305 TPI
Transmission: 5 speed
Axle/Gears: 3.23 posi
Re: optimal ratio?
thanks for the feedback. i think ill go with the 3.73:1. now just to find the donor car for that transmission...
Last edited by squatingeagle; 04-26-2009 at 06:12 PM.
04-26-2009, 06:51 PM
#7
On Probation
Join Date: Oct 2008
Location: Northern Utah
Posts: 6,319
Likes: 0
Received 17 Likes
on
17 Posts
Car: seeking '90.5-'92 'bird hardtop
Engine: several
Transmission: none
Axle/Gears: none
Re: optimal ratio?
Lets hope your donor car isn't a '93 with a 2.73:1 axle, that T56 had some unique ratios in it: 3.36/2.07/1.35/1.00/0.80/0.62
Trending Topics
04-30-2009, 02:18 PM
#9
Junior Member
Join Date: Mar 2009
Location: Decatur, IL
Posts: 2
Likes: 0
Received 0 Likes
on
0 Posts
Car: 88 Iroc-Z
Engine: 305TPI
Axle/Gears: 2.73
Re: optimal ratio?
I have and 88 Iroc-Z TPI. I am waiting on 3.73 gears on back order and I was wandering it these gears would be the better gears for my car comparing them to 3.42. Something that performs well 1/4 mile or less is what I'm looking for. I have a K&N air filter and aftermarket exaust that was on the car when purchased. Next performance mod will be headers. Is there anything I should know before I get these gears put in.
Thread
Thread Starter
Forum
Replies
Last Post
Damon
Tech / General Engine
8
09-26-2015 04:29 PM
83 Crossfire TA
Suspension and Chassis
0
09-08-2015 12:06 PM