transmission & axle

[vb101]

It has been stated on this forum that the 7.5 can only handle 300 lb/ft of torque, considering the V6 starts off with 240 that doesn't leave a lot of room. CAI, headers, duals and underdrive pully would probably get the engine pretty close to that 300 mark. Supercharging with no other mods would get it there and maybe over. Is there anything that can be done to strengthen the axle enough to handle up to 350 lb/ft of torque, short of swapping it out for the 8.8?

What about the T5 transmission? How much torque can it handle? If it can only handle 300 like the axle then is getting a stronger after market transmission to replace the T5 the only option?

If the transmission and rear axle have to be replaced if the engine is pushed over 300 lb/ft of torque then it seems to me that it would be better to just trade up to the GT if you want over 300. Otherwise it's just too much work and expense.

One last question. how does increasing the gear ratio effect the axle strength wise. That is if you mod the engine to where it's putting out around 280 or 290 lb/feet of torque, about 250-260 hp, would changing the axle to 3.73 gear ratio be too much for it?

If keeping it under 300 for torque and just bumping the gears will not destroy the transmission or rear end then I plan on getting my engine as close to 300 lb/ft of torque as I can. I don't need to be running with the big boys, Corvettes and Cobras. I just want to have respectable performance without killing my car. Though it would be nice to get my car at least into the upper 13's in the 1/4. Don't know if that can be done with the T5 & 7.5.

Any info on the drive train limits would be much appreciated. It'll give me an idea where to go with the engine.

 

[Jenns01TA]

vb101,

Good Questions. Same ones that I have been pondering since going from a 03 GT to the 05 V-6 AOD.

Here is the technical specifications from TTC for the Tremec T-5 Transmission.... T-5 has a torque cap at 300 lbs-ft tq. The TR-3650 used in the GT is capable of holding to 360 lbs-ft tq.

http://www.ttcautomotive.com/English/products/T-5.asp

I wish Ford would use the T-56 in the GT, but then they wouldn't have the SVT high end to market if we could get that stock... LOL The T-56 is also used in the Vette and Viper and is capable of handling a beating. The integral clutch adaptor with front cover end-loading design provides for increased driveline bending strength and greater application adaptability. I have noticed that there are some out there that have been pushing the new GT with S/C by Vortech, Procharger and Kenne Bell and have not indicated a need for a tranny swap, so that leaves meto believe that the TR-3650 is capable of handling well above TTC specifications.

As for the comment on switching up to a GT due to the capital outlay for the Tranny, Gears and rear diff, well; that is a hard call. I, personally, can't due to my mother's medical condition necessitating a large monthly outlay of cash. A fixed monthly payment on the GT would not be smart right now. Plus, I got a DUI in my 03 GT. I was doing 55 in a 35 plus had a .19 BAL. My insurance rate was insane on the GT, and although I had paid for it with cash, opted to sell it when mom got sick. However, if I can sneak in the modifications when the warrenty on the 05 runs out and push my V-6 to within the GT specifications, then, I am a happy woman. Why others will, or will not trade-up to a GT, I cannot speak.

I am in no way even half-way intelligible when it comes to gear ratios and gearing. I can understand the simplistic engineering behind them. I will be happy to table this question to someone well informed in this area...

I am anxious to see some additional responses...

Jennifer

It has been stated on this forum that the 7.5 can only handle 300 lb/ft of torque, considering the V6 starts off with 240 that doesn't leave a lot of room. CAI, headers, duals and underdrive pully would probably get the engine pretty close to that 300 mark. Supercharging with no other mods would get it there and maybe over. Is there anything that can be done to strengthen the axle enough to handle up to 350 lb/ft of torque, short of swapping it out for the 8.8?

What about the T5 transmission? How much torque can it handle? If it can only handle 300 like the axle then is getting a stronger after market transmission to replace the T5 the only option?

If the transmission and rear axle have to be replaced if the engine is pushed over 300 lb/ft of torque then it seems to me that it would be better to just trade up to the GT if you want over 300. Otherwise it's just too much work and expense.

One last question. how does increasing the gear ratio effect the axle strength wise. That is if you mod the engine to where it's putting out around 280 or 290 lb/feet of torque, about 250-260 hp, would changing the axle to 3.73 gear ratio be too much for it?

If keeping it under 300 for torque and just bumping the gears will not destroy the transmission or rear end then I plan on getting my engine as close to 300 lb/ft of torque as I can. I don't need to be running with the big boys, Corvettes and Cobras. I just want to have respectable performance without killing my car. Though it would be nice to get my car at least into the upper 13's in the 1/4. Don't know if that can be done with the T5 & 7.5.

Any info on the drive train limits would be much appreciated. It'll give me an idea where to go with the engine.

 

[fazm83]

i can only vouch for the old automatics, my 01 gt has a 175 shot (NOSzle) and never had any problems with the auto tran.

 

[vb101]

Jenns05Stang, I checked out the website you gave. Unfortunately, going by the gear ratios listed for the T-5 and the gear ratios listed in the specs for the V6 mustangs apparently the T-5 with ratios the same as in the Mustang specs pdf is rated at only 175-230 for torque which is below the peak torque of the V6. The two model numbers listed on the Tremmec website that have a max of 300 have different gear ratios than what is listed in the mustang specs I got from the ford website. I find it hard to believe Ford would use a transmission that is rated to handle less torque than the engine actually puts out.

I hope these numbers are underestimates or the T-5 in our Mustangs are not listed on this site.

BTW, I know virtually nothing about transmissions, but I'm learning.

 

[Owner1]

In answer to the question of whether lower gearing would affect the amount of torque the 7.5" could handle--the answer is yes. Lower gears harness more of the engine's available torque at low RPM. This means more stress on the tranny and rear-end. The effect is called torque multiplication.

I wouldn't worry about the T-5, but I would worry about the 7.5" axle. In 1985 the 7.5" rear was used on the 5.0 Mustangs rated at 210 HP. and 295 torque. That engine, stock, broke the 7.5's consistently. My friend went through 3 new 7.5's in 3 years, then finally went to the 8.8 and never had a problem.

I used the T-5 "Z", and the 8.8 in my own '86 GT with over 400 hp/400 ft/lb of tq, without problem.

Owner1

 

[Chris_NY]

A good way to put the whole gear ratio thing in perspective is a 10 speed bicycle...

Everyone has rode a 10 speed right?

Think of the gears .. the lower ones are easy to pedal but you go no place .. The higher gears are HARD HARD to pedal but for every revolution of the pedals you go FAAAARR...

Same thing with rear end gears...Lower gear ratios = Easy for the car to spin the ring and pinion but you don't go so far for every revolution of the drive shaft .. Higher ones like 3.73 or 4.11 .. make you go further for every revolution of the drive shaft .. But remember those pedals and how HARD you had to push to propel yourself? Now think of how the car feels

 

[RedCoupe92]

ok, the T-5 can and will handle more than 300lb ft of torque. my old 92 has the old T-5, before Tremec was making them, and my car has about 400lb ft torque and 525hp with the Nitrous. So I wouldn't worry about the tranny, now the rear end, that is another story. the 7.5 rear will take more power, but it's how you drive it that will kill it. are you planning on drag racing and dumping the clutch at around 5000rpms? if so, replace it with an 8.8 before the first run, because the 7.5 will not take that kind of abuse. but for every day driving and playing around, as long as you are not dumping the clutch all the time, or racing with super sticky tires, it too should be fine. but i agree, if you have plans to make over 300hp and 300ft lbs, why didn't you just get a GT and spend the money up front? just my 2 cents.

 

[vb101]

If the tranny can handle 300 ft-lbs or more of torque I'll be happy 'cause I don't plan on going over that for a long while. Since I don't ever plan on dumping the clutch at all even if I do occassionally take it to the track then the rear end will be good until I decide to get serious with the horses, finances permitting.

As for why I didn't get a GT... I didn't feel like driving 500+ mile away to avoid the $3000+ markups. Basically I couldn't afford one. At least with the V6 my notes aren't going to brake my piggy bank and I can beef it up over time as I get the money. Heck I couldn't even order a GT. By time I got to place an order the dealerships in the area had stopped taking orders. Bummer. I'm quite happy with my V6 though.

 

[RedCoupe92]

i'll be honest, if i were to buy one today, which i am not in no financial shape to, i would get the v-6 myself and i am a gearhead. i know the GT has 300hp so what, it to me doesn't look as good as the v-6. i like the v-6 looks with the wheels and black skirts and fog light delete. the only thing i would do to one, i would lower it, tint the windows, change the factory balloon tires for wider more low profile ones and just drive it and enjoy it. after 13 years with a fox body and over 500hp, it's time for some comfort and just cruising. but yeah the trans should be fine. i am no mechanic, just stating what is rated is not always true.