Viper OD 5th and 6th pros and cons?

svt_steve_svt

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Thinking about putting the Viper 5th and 6th gears in my stock t56. Is it worth it? What all is needed for the swap? What differences did you notice afterwards?
 

Roush6018

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i have the viper 5th and 6th gears and i am running a 3.55 rear diff. i had a transmission shop install them and i upgraded the input shaft also during the rebuild. the 5th gear has very good acceleration still, its less of an overdrive gear and pulls hard. but the 6th gear really has no power at all its so much of a overdrive, 6th gear gets great gas mileage because you cant make a pull in that gear,

i use the 6th gear when i am at 80mph , but if traffic is at 70mph i usually use the 5th gear. i totally recommend this mod.
 

01yellercobra

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Friend of mine did this mod to his 04 when he installed 3.73's. He actually wasn't a fan. He said any time his was in 6th any acceleration put him into boost. And with a 3.4 Whipple it wasn't a small amount of boost.

You have to remember these are small engines. They don't like lumbering along at 1500rpm. They don't have the torque for it. I usually cruise at 80 too, but I wouldn't want to have to get there just to use 6th personally.

I think knowing the kind of MPG @Roush6018 is getting compared to what you get is worth knowing. And knowing the type of area you drive in. Flat areas are different than hilly areas.
 

svt_steve_svt

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Friend of mine did this mod to his 04 when he installed 3.73's. He actually wasn't a fan. He said any time his was in 6th any acceleration put him into boost. And with a 3.4 Whipple it wasn't a small amount of boost.

You have to remember these are small engines. They don't like lumbering along at 1500rpm. They don't have the torque for it. I usually cruise at 80 too, but I wouldn't want to have to get there just to use 6th personally.

I think knowing the kind of MPG @Roush6018 is getting compared to what you get is worth knowing. And knowing the type of area you drive in. Flat areas are different than hilly areas.
main reason I think it would be more worth it to me is because of the 4.10’s I have, think it would actually be worth it with those?
 

DSG2003Mach1

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What’s that have for 6th gear?

My wide ratio magnum has the .50 I think. With 4.10s 80is is a hair over 2k. 70 is maybe 1800. I spend a lot of time in 5th around town
 

Roush6018

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it has been so long since i put these gears in my t56. the D&D website is much different now. i ordered the gears and tried to put them in myself, i couldnt handle it and i put all the gears in a box, took the case and the box to my transmission shop and he had it built in 1 day, he could identify the gears blindfolded. BIG shoutout to All Standards in Campbell,Ca.

the stock 03 cobra t-56 has .80 5th and .63 6th
the viper spec 5/6 has .74 5th and .50 6th.

so, if you had 2 bone stock cobras and only one had the viper spec gears. starting from a 60 roll in 3rd, then 4th still even, then in 5th the viper gears would pull harder up to 130mph. the viper 6th would only pull at 120+.

i commute 25 miles each way and sometimes in heavy traffic, and running the A/C compressor to use the defroster when its cold. i have a stock upper with a ported blower, stock injectors, stock MAF. i have headers, all 4 cats, SLP catback. K&N intake and a Twin disc clutch i can drive in sandals.

i just ran this car this week. Last week i filled up with 12.8 gallons and i thought i had a 13 gallon tank but maybe its 14 gallon. i have 171 miles on this tank and its about 1/8 full, pretty low. i think i could get 15 more miles. i have been boosting all the time and revving it at stoplights and downshifting when possible.

if i get 185 miles on 13 gallons i am getting 14.2 mpg. i could get 200-210 miles per tank if i drove it easy.
 

01yellercobra

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For the 4.10's it might be worth it. I know I was considering it when I had the 3.90's in my 01. I just wanted to cruise at a little lower RPM.

96-04 Mustangs all have 15 gallon tanks.
 

biminiLX

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Sorry not Cobra related but ‘13-14 GT500s also come with this OD combo and I personally liked to cruise in 6th at 80mph with 4.10s.
You shouldn’t use 6th to accelerate anyway really so around town I MUCH prefer the 4.10s as the car responds so much better off boost with that gear.
Cobras aren’t light either so, if you’re running a gear higher than 3.73 or if you routinely do highway driving I’d recommend it.
For 3.55 stock gearing and little highway use I would think it’s worth the money.
Good luck.
-J
 

IllCobra

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I got my T56 magnum with viper spec 5th and 6th gears ratios. When I was ordering the magnum, I wasn't 100% sure if I wanted 5th that spec, but I for sure knew I wanted 6th since I would have to shift down regardless if I ever needed to pass someone. Plus the car does see a bit of hwy driving/cruising. Now that I have driven the car with the magnum and this gear ratio, I really like it. I never need to get out of 5th in the city. And 6th is awesome on the hwy - 90mph at just under 2200rpm and <1700rpm at around 80mph (which is my normal hwy driving speed).
Note, that I live in FL so no hills. Stock 3:55 gears on 305/35/18 tires/rims.
 

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