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Roadside Jerry
Roadside Jerry, Auto Mechanic
Category: Car
Satisfied Customers: 2948
Experience:  Auto Mehanic 39 years,30 with the NYPD Fleet Service Division
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10/2/2007 9:57

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I own a 98'' Mustang GT, 4.6l, 281(Automatic!!)with a few boltons...
70mm Throttle Body, 80mm Cold Air Induction Kit Mass Airflow Sensor, Underdrive Pulley Kit, 24lb Fuel Injectors, MSD EDIS Coil Pack, DiabloSport DeltaChip Performance, Venom 400 Control Module, BBK 1-5/8” Full-Length Header (Chrome), BBK 2.5” Short H-Pipe w/ Converters Spintech Cat-back 2.5” System (Chrome Tips) 125shot Direct port EFI NOS kit
Im in the process of getting a 125shot NOS kit installed...

My transmission is near dead and leaking all over...

Im looking at the transmission "kit", Level 3 - Interceptor Extreme

From the following website...

Is this a good option!!!??? Its rated at about 700HP...

I have some questions about the Level 3 transmission...

- Ive been told I NEED a transmission cooler... Is this true?

- Would it be possible for the shop selling the transmission to "pre-install" a manual shift kit? (If the offer such service... I just wanna know if its possible.)

Ill be swaping out transmissions my self, I need all the help I can get!! ;-)

- Is it difficult to install a manual shift kit?

- I assume Ill need a new shifter with a reverse lockout and neutral safety switch...
Which one do you recommend for my car and transmission and what happens with the OD button? Would that be the 4th gear!!??

graphicgraphicgraphic Hello SilverStang, thanks for asking your questions at Just Answer.The Interceptor Extreme looks like a quality unit,although I have not heard of this company before,it looks like they know their stuff when it comes to modified transmissions.

The transmission cooler is a must,the cooler the unit runs the better.

The manual shift kit would be best to have installed by the units builder,since the would not want the unit tampered with by others.

I will send info to JEGS,then have a full line of shifters,the lock out and neutral switch are built into them,the OD switch can be addressed with a toggle switch.OD is your 4th gear.

I will send instructions for replacing the transmission,the problem would be raising the car high enough to remove it,and a jack to support the transmission as it is lowered out and raised up to install. This is a job best done on a lift,using a transmission jack. I hope I have answered your questions,good luck with you project,and stay safe,Jerry.



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Customer: replied 9 years ago.

Thanks for all the information!
Ill be changing the transmission in our "car craft shop" on post... They have all the equipment I might need!

I have one more question my friend!
Ill also be installing my nitrous kit when I go home... Many of the safety devices included with the kit are set off by "RPM range"... For example the "RPM window switch"...

How will the "manual shift kit" affect my computer and my "nitrous application"?
Im not sure how to phrase my question... I guess Im just looking for someone to shed some light on how the whole "manual shift kit" works on an automatic transmission...
Ill still have an automatic trans, but Ill have control over every gear... I would imagine that you cant just shift from 3rd to 1st while flying down the road! I would also assume that you would have to take the same precautions as when driving a "stick"... Im sure I cant just put it on 1st and step on the gas!

What are some things Ill have to keep in mind when driving with the "shift kit"?

My other two cars are stick shift... the mustang(unfortunately)is the only automatic car I have... Thats why Im interested in a "shift kit"...

Ive never drove a car with a "shift kit",I guess I just want to know the "do" and "donts" about it!

My other concern is the Nitrous... Although nitrous can be installed in an automatic or a stick... Automatics are much safer when it comes to the use of nitrous.

Will this "shift kit" put me at a higher risk of "disaster" when using nitrous!?

The nitrous kit I purchased includes a wide open throttle switch that connects directly to the TPS, my guess is that none of this will be affected by the "shift kit" but I just want to make sure...

I would like to work on my car when I go home on leave and have it up and running in a matter of a few days... If I run into any problems, I wont be able to get this done... Any car part I order from the states, will typically 2 to 3 weeks to arrive!   

   I apologize, it seems my question has evolved into a "book"...

I dont have a problem paying for 2,3 or even 4 questions... Please let me know how to go about making another payment!


Hi Hector I checked out the Mustang website,nice cars and ladies. I am going to send some info on the manual shift kit. You would have to take the same precations as when driving a stick,don't downshift from 4 to 2 at high speeds high speeds,and dont hold to long in any gear and over rev the engine.You shouldn't have any more fear of launching an engine (heaven forbid) when using the automatic.You will have control over up and downshifting,and will still have automatic shifting when put in 4th gear.The nitrous kit should have no problem workin with the automatic trans. If you choose to accept this anser,click on the accept, no need to hit it more then once. Thanks again,and good luck,Jerry.


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Customer: replied 9 years ago.
Hi Jerry,

Once again, very informative! Thanks for all the help...

This is what I dont understand...

Ive read the following about some shift kits,
"Holds the gear you select to any rpm"

This statement makes me think I can just slam it in 2nd or 1st gear at any speed and nothing would happen! Which sounds plain crazy!


This thing can get pretty complicate if you know nothing about transmissions (Like myself!)...

OK, so I have to make a distinction between:

* Manual Valve Body: Turns your auto tranny into a partial-manual tranny.
* Shift Kit: Makes your auto tranny do the exact same thing it does now, but better.

So I guess what I really want is a "manual valve body"... which means, no more "drive"!

The stock gears, are PRND21 from front to back. The shift kit makes it PRN123 from front to back, and putting it in 3rd makes the tranny go into 3rd. Unlike "Drive" starts in 1st, and climbs "Automatically" to 3rd. Whatever gear you pick, it goes there and stays, like a manual.

Now... a "manual valve body" means, that if Im cruising a 90MPH and throw it into 1st gear... Ill blow my engine right out of the bay and Ill be walking home! ;-)

Would a "manual valve body" have an affect on the automatic safety features of my nitrous kit?

I assume that if I get a "manual valve body" Ill definitely need a new shifter with a reverse lockout and neutral safety switch... Right?
(BTW, How does the manual shifting work??? Do I have to take my foot off the gas when I shift gears???)

Then you have "lockup converters" that give you an "additional" gear and "Over drive" that gives you excessive Overlap" or the other way around! I still dont have a clear understanding of how this all works and I dont expect you to explain it all to me...

But, what happens to the OD button? Are we still talking about a toggle switch solution?

I really dont understand the purpose of the OD button anyway!I could do without it! I really cant think of an instance when Ive switched it off! What is there to gain from switching it off!!?
Any gains in "power" or acceleration??

I guess my final question would be, Is a "manual body valve" a good idea??

I dont spend all my days on the track, but the car is really a "hobby"... Whenever I pull it out of the garage, Im likely to "drive it like its stolen"! I really only drive it for 2-4 months a year...

The reason I ask is coz I heard a guy make the following statement:

"A manual valve body means that it will not shift on it's own you have to shift it up or down.
If you try to run a manual valve body on the street it will burn up they are for race only.
If you get just a shift improver kit it will make it shift harder."

It sounds kinda wild... Is there any truth to this statement!? I dont really understand why it would "burn up" under normal driving conditions...

Thanks again for all your help!
I feel bad for my lengthy questions/replies... At the end of all this Ill be paying for 3-4 questions or a "bonus"!


Hello Hector,thanks for the accepts ,the bonus,and the nice comments in the feedback section. I am going to try and answer the questions the best I can,and send you some info on automatic transmissions.

A shift kit is used when rebuilding a trans,to improve the life of the trans.It raises pressure,may allow the trans to shift at a higher speed . The problem is you may feel the shifts,which some people don't like,it wont bother some one that is seeking performance.

A manual valve body,goes further and lets you choose the gear range your self,but most also let you retain the auto shifting if desired. You have to check this out when you purchase it from the vendor. You don't take your foot off the gas when shifting on of these,keep your foot to the floor . You can hold any gear,but don't want to down shift from a high gear to lower gear,under full power,it puts to much stain on the drive train. Same as if you had a manual trans.

The manual valve body won't affect the saftey feature of the Nitrous kit.

You do need the N/S switch,and the reverse lock out is a good feature.

OD and lock up converters are not the same,OD is when the trans output shaft spins faster then the engine,used for fuel economy,or more top speed when on flat level. ground. The OD button is used to eliminate OD when driving in hilly areas or towing.

Lock up converters lock up to eliminate slip between the engine and trans.Lock up comes on when cruising in higher gears only.

I don't think you will have any problem with the manual valve body causing the unit to burn up when driven on the street. The trans you have chosen seems made for the use you will be giving it.

Thanks again,Jerry.



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