Final Drive Ratio Change
- Thread starter texasgt
- Start date
Empty Pockets
ex-GT Owner
WHAT???! You mean you'd jeopardize "the magic number"???!:rofl
What about going to "the source" for your higher gears - Ricardo???
fjpikul
GT Owner
This was investigated quite extensively, especially by the boys from New Zealand. It ain't possible or worth it. Look at the old posts.
GERMANORACING
GT Owner
Just took a glance at some older post on this subject, (some excellent posts)
Are you guys telling me that there is absolutely nothing that can be done to change the ratios at this time or even in the near future ?
Very disappointing.
One of my favorite cars I had in the late 80s was a 930 Turbo , It ran a 13.03 in the 1/4 mile all stock , the only thing I changed was a borla exhaust / fuel enrichment kit and GEAR RATIO , car ran consistent 12.01 ets.
Track and all around street driving was (Jeremy would say) astonishing.
Gear ratio change would be the best performance upgrade we can do to the Ford GT.............. Hope someone comes up with something
nz05gt
GT Owner
3.9 to 1 RATIO
This ratio will be availible soon,this will be the only ratio riccardo are making,it will be availible from 'STILLEN' soon, ie few months
I also know where there are 2 complete transaxles with 3.9 ratio's in them from the original test/development program 1 is new 1 is used
This ratio will be availible soon,this will be the only ratio riccardo are making,it will be availible from 'STILLEN' soon, ie few months
I also know where there are 2 complete transaxles with 3.9 ratio's in them from the original test/development program 1 is new 1 is used
dbtgt
One lucky SOB to own a GT
Alternative to gear change
A Heffner pulley and tune will get you where you want to be for a lot less $$$, IMHO:banana
A Heffner pulley and tune will get you where you want to be for a lot less $$$, IMHO:banana
californiacuda
GT Owner
- Oct 21, 2005
- 919
A gear change as suggested is usually beneficial when not enought engine torque/hp is available, and more torque mutiplication is needed.
If, instead of spending $ on the transaxle gear change, put on a Whipple you will have massive power everywhere, and 1st gear won't feel so tall. With the new sc you can fry the tires all throughout 1st gear. Then if you want more performance, stickier tires are the next step to plant the power.
I have an Subaru Sti, and with th stock 300 hp the 6 speed gearing felt fine. Now that it have over 600 whp, the gears are way to short and I feel like I'm constantly shifting trying to keep up with increased engine power.
With increased hp/tq 1st gear does not feel too tall.
If, instead of spending $ on the transaxle gear change, put on a Whipple you will have massive power everywhere, and 1st gear won't feel so tall. With the new sc you can fry the tires all throughout 1st gear. Then if you want more performance, stickier tires are the next step to plant the power.
I have an Subaru Sti, and with th stock 300 hp the 6 speed gearing felt fine. Now that it have over 600 whp, the gears are way to short and I feel like I'm constantly shifting trying to keep up with increased engine power.
With increased hp/tq 1st gear does not feel too tall.
GERMANORACING
GT Owner
What kind of cost could the gear change be, any idea . Labor+Parts
I was thinking > a pulley/tune/exhaust and a GEAR RATIO change would cost less then a whipple and out perform a whipple change.
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dbtgt
One lucky SOB to own a GT
While I have no data about cost for a gear change, I strongly suspect it would be quite expensive IMHO.
AZGT
GT Owner
:thumbsup
Somewhere I wrote about ratios (with a little about mathematical determination of ideal ratio). From memory (too lazy to look it up) I think the 3:90 seemed to be ideal. Glad to hear they are coming out with it. Interested to see what the cost is to have it installed.
And then when I thought further about gears and reality set in, I was not quite so sure. They do seem tall at the stop light, etc. Shorter gears would make general around town driving easier. However, when a stock GT is pushed and runs in the 3+ second 0 - 60 range with the high gears it has, dropping the gears significantly to the 3:90 means you better be damn well ready to shift out of first REAL FAST because you're going to be red-lining in the 2 second range. Traction will also then be a issue. Problem is, this ain't your father's Buick. Compound that with any performance upgrades, and you may just as well get it rolling in first and go right to second. In that case you tend to be back where you started (unless you want to pull tree stumps). So, not really sure if it would help or not, unless you are just going for groceries. :thumbsup
Somewhere I wrote about ratios (with a little about mathematical determination of ideal ratio). From memory (too lazy to look it up) I think the 3:90 seemed to be ideal. Glad to hear they are coming out with it. Interested to see what the cost is to have it installed.
And then when I thought further about gears and reality set in, I was not quite so sure. They do seem tall at the stop light, etc. Shorter gears would make general around town driving easier. However, when a stock GT is pushed and runs in the 3+ second 0 - 60 range with the high gears it has, dropping the gears significantly to the 3:90 means you better be damn well ready to shift out of first REAL FAST because you're going to be red-lining in the 2 second range. Traction will also then be a issue. Problem is, this ain't your father's Buick. Compound that with any performance upgrades, and you may just as well get it rolling in first and go right to second. In that case you tend to be back where you started (unless you want to pull tree stumps). So, not really sure if it would help or not, unless you are just going for groceries. :thumbsup
californiacuda
GT Owner
- Oct 21, 2005
- 919
Well, I think there are many ways to skin a cat.
Hope that there hasn't been too much negativity to your idea. Getting more performance, its the best goal. Lets think about it some more and discuss tomorrow. Good luck.
Hope that there hasn't been too much negativity to your idea. Getting more performance, its the best goal. Lets think about it some more and discuss tomorrow. Good luck.
californiacuda
GT Owner
- Oct 21, 2005
- 919
I have some custom 18" wheels with bfg 345/30/18 tires. They are only 26.15" tall. The rear axle ratio stock is 3.364. With the tires I now have, the effective rear diff ratio changes to 3.72. I am located in LA, If anybody want to borrow the tires and wheels to see how a 3.72 feels, they are available. My car is heavily modified and currently not running.
That would be an interesting experiment, assuming you could isolate the feel of the effective gearing change from the ride height and handling.
I would certainly give it a try but I am far away in Texas. Have you driven your car with these wheels?
Thanks
I would certainly give it a try but I am far away in Texas. Have you driven your car with these wheels?
Thanks
californiacuda
GT Owner
- Oct 21, 2005
- 919
Unforunately, I haven't.
In an SAE report (2004-01-1252) that Ford wrote concerning the gt's power train, a graph is shown measuring the "tractive effort" in lbs/per. The chart shows how much force is applied at the rear wheels in each gear. I was shocked, I had no idea that in 1st gear at peak power 3745 lbs/ft is being put down.
This is with everything stock. The power level takes into account flywheel tq, transmission gear ratio, differential gear ratio, and tire radius. In 6th gear the max "tractive effort" drops to around 900 lbs/ft.
The reason that I thought this might be interesting is that with a rear differential gear change to 3.90 the peak forces would increase, but as the gearing gets numerically higher (with more torque multiplication ) the time that you can spend in each gear is reduced.
Maybe somebody with better computer skills can post copy of the chart. I wonder how much peak "tractive effort" Joe's car is making?
In an SAE report (2004-01-1252) that Ford wrote concerning the gt's power train, a graph is shown measuring the "tractive effort" in lbs/per. The chart shows how much force is applied at the rear wheels in each gear. I was shocked, I had no idea that in 1st gear at peak power 3745 lbs/ft is being put down.
This is with everything stock. The power level takes into account flywheel tq, transmission gear ratio, differential gear ratio, and tire radius. In 6th gear the max "tractive effort" drops to around 900 lbs/ft.
The reason that I thought this might be interesting is that with a rear differential gear change to 3.90 the peak forces would increase, but as the gearing gets numerically higher (with more torque multiplication ) the time that you can spend in each gear is reduced.
Maybe somebody with better computer skills can post copy of the chart. I wonder how much peak "tractive effort" Joe's car is making?
Empty Pockets
ex-GT Owner
californiacuda
GT Owner
- Oct 21, 2005
- 919
That's what I was talking about a few posts ago. As power increases, the need to use a higher numerical rear differential (3.90) diminishes. And I would guess that if Joe had his druthers, he would prefer a numerically lower, say 3.00, or maybe even lower.
On a stock car 1st gear feels to tall, but for Super Joe, the stock gearing is too short. Who woulda thunk?
So, if your going to stay with stock hp, than maybe a 3.90 would be quicker. When hp is upgraded, then the need for shorter gearing diminishes.
On a stock car 1st gear feels to tall, but for Super Joe, the stock gearing is too short. Who woulda thunk?
So, if your going to stay with stock hp, than maybe a 3.90 would be quicker. When hp is upgraded, then the need for shorter gearing diminishes.