1994 4.6 Bird - Speed limiter

90sc35thann

Registered User
How can we eliminate this? It is very annoying not being able to go any faster than 105mph. Is there a way around this without an aftermarket chip? Any help would be appreciated.
 
You will need to get both a drive shaft and a chip.

Get a 93-98 Mark VIII 4R70W 58.20"Lg aluminum drive shaft from a junk yard if you do not plan to go over 3.27 rear end ratio. The earlier one piece shafts are better (93-94).

If you want to use over 3.27 then I suggest you get a composite drive shaft from Dynotech Engineering.

For the chip may I suggest Blue Oval Chips Inc..

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The design of the driveshaft is not suitable for the load at high speed with higher rpms. That's why it's suggested to change it.


cheers
Ed N.
 
Depending on the material it is composed of a drive shaft will start to bend or osculate when it reaches a certain RPM. An aluminum drive shaft is lighter so it will spin at a higher RPM level before critical oscillation. The same with some composites.

Now I understand that normal metal drive shafts can be reinforced for higher speeds but with the length of the 4.6L drive shaft that will not be the best solution.

A police vehicle reduces this effect by lengthening the transmission and shortening the drive shaft. Therefore increasing the maximum rotation of the shaft... :eek:

Your car has a speed limiter built into it that protects your from a broken drive shaft and possible injury. This is why you should upgrade the shaft before you go with the chip.
 
I'm with J.Miller that stock driveshaft is crap. I currently have a 2 piece shaft installed in my car froma markVIII...I would not suggest going that route either as I get vibes near the 90mph mark with my 3.73's and I had the shaft balanced. The 2 piece shaft is basically filled with rubber making it marginally better than the stock crimped together garbage. I bought a 1 piece aluminum shaft for less than 400 in a group buy on tccoa a while back. I'm sure if you search the threads there you can get information to that company and get one of those made. I haven't installed mine yet, but I'l be swapping converters again next week and hopefully I'll remember to do it when I have the transmission down this time. If you can find a 93 markVIII shaft you are doing good,but they are hard to find 90% of the "93" shafts I see are not true "93" shafts so buyer beware if you can't visually identify it as a 1 piece shaft just leave it be. Look for a split about 8 inches from the rear in there you can see the rubber that bonds the halves together.
Alan
 
so the 93 driveshaft is completely solid like the lx driveshaft but aluminum?
i found one on a website im going to go look at
 
Go to the TCCOA web site and there are articles about the shaft & trans. concerns, as well as a wiring defeat for the limiter. Even though the 4.6 stock shaft is 0.20" longer than my '94 SC the 105mph limit is a bit low. The SC is 127mph.
 
titanium89scguy said:
so the 93 driveshaft is completely solid like the lx driveshaft but aluminum?
i found one on a website im going to go look at

The stock lx one is crimped together.
 
I guess no one better tell 1BadT that his driveshaft may explode at speeds over 105mph. He had Jerry remove the speed limiter on his 4.6 several years ago. He cruises the thing regularly at 120-140 with 3.73 gears.

Seriously, not to make light of the driveshaft issue, the bottom line is that the speed limiter on the 4.6 bird had a lot more to do with the tires than the driveshaft. Stock tires on the car were rated for 112mph.
 
XR7 Dave said:
I guess no one better tell 1BadT that his driveshaft may explode at speeds over 105mph. He had Jerry remove the speed limiter on his 4.6 several years ago. He cruises the thing regularly at 120-140 with 3.73 gears.

Seriously, not to make light of the driveshaft issue, the bottom line is that the speed limiter on the 4.6 bird had a lot more to do with the tires than the driveshaft. Stock tires on the car were rated for 112mph.

With all due respect, I paid that guy two times to tune my car and all of them were no good... Instead of trying to make nice he tried to silence me.

As far as going over the speed limit goes some get away with it and some do not. Most of the reports I have heard were not of exploding driveshafts but were due to drive line oscillation and vibration. Not saying that it can not explode, because that is possible, but it can also prematurely get off balance and make noise.

When I purchased my driveshaft I sent it out to get balanced. They informed me that I really did not have to purchase an Aluminum drivesahft since they can strengthen a stock drive shaft to take higher RPM levels. I was told that this is common practice among the Mustangs in that area.

In the end it is your life and you can do what you want... I would personally advocate that Safety Comes First and spending a few hundred to insure that your car is safe is a good thing. So I went for both the high speed tires and aluminum drive shaft. Not that I drive fast or anything...
:eek:
 
I'm with dave. My 94 4.6 was a 1000$ car. but I still pulled the speed limiter and cranked the trans pressures up. The car ran way better then before. I also swapped to aset 3.73 gears in that car and it saw 120+ over 20 times on the dyno while tuning alone. Not to mention the speed it saw on numerouse road trips. If you figure the gear swap into the equation, and do the math, the DS on this car was spinning as fast at 120 as it would be at 140. It was 130K mile car as well.
 
I guess the thought of driving those kind of rpms through a shaft that resembles two pop cans crimped together just scares me.
Alan
 
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