Hey guys,

You all probably know I have a 2003 F150 supercab 4.2L V6 that I had Steeda switch out the 3.55 diff gears to 4.10's. Well, ever since i've done that i get a really bad vibration coming from under the truck as I pass 85 mph.

My theory is that the drive shaft is not balanced well enough to handle the increased rpms at higher speeds. My question is can I replace the drive shaft with another one that is more equipped to handle the higher rpms, if my theory is correct of course.

My tranny is a 4R70W and I have the standard differentional gear box. Couldn't I replace the drive shaft with a 5.4L drive shaft or something that's better balanced.

Or perhaps I'm way off and it's not my drive shaft at all. I need to do something because right now my truck is not capable of speeds over 87 mph, which will seriously hinder my future 1/4 mile times.

Help.

Thanks,

Tom Longo

 

I would explore the obvious first, if your truck ran fine before the gear change then aparantly they didn't line the gears up correctly. Make them re-adjust it. Its not uncommon for a gear swap to not be perfect the first time.

I used to have a little 4.2 with a 5 speed I bet with those gears and the added jolt of nitrous it is a fun little truck. I thought mine was a blast considering it was a 97 six but mine was a reg cab so the weight issue was on my side. I know there was a couple of times I smoked the tires and people thought I had a v8 in it, what? that thing has a six? Doesn't have the low end grunt of the inline but man it does have pep for moving the truck along. Are you aware they make superchargers for your 4.2? Later

 

Taylor,

You win the prize!! I called Steeda and they told me to bring it back for an adjustment. Bad Steeda, Bad! Go to your room, no desert!

I'm dropping it off tonight and there going to fix it tomorrow. I'll let you know how it is after I pick it up.

You were spot on! Thanks.

I've checked into the superchargers but too expensive and don't look too reliable.

I was planning to run it at Moroso tonight, but I'm dropping it off at Steeda instead. I'll run it Friday with my newly programmed chip and I'm estimating that with the 35 shot I'll be in the low 16's. Which is already faster than my friends Dodge dakota r/t 5.9L ! He hates me!

After I switch to the 50 shot that should put in in the mid to high 15's, which is faster than alot of stock Lightnings. Then I'll be dropping in the 75 shot along with 2600RPM stall Stallion converter, will put me into the 14's I'm sure.

Then I'll be smokin'. And people WILL freak when I tell them I'm only running a 6 in my huge super cab automatic.

That's whats fun about taking something that wasn't meant to be fast and making it fast. It's the responses from people when you tell them what motor your running. It's also been a great learning experience for me, mechanically speaking.

Thanks again,

Tom Longo

 

Yeah let me know how it turns out with the gear adjustment and the 1/4 mile times. You have a point on the superchargers though all info on kits has been kind of iffy if you know what I mean, still doable. You might as well throw some forged internals in it and put a 200 shot on it and see how quick you can blow that tranny outta that truck. haha. Yeah a higher stall should help pep things. Keep me updated I find your project interesting. Later

 

It certainly is a work in progress.

I just got the truck in July. Only have 3500 miles on it. It's barely broken in. After Steeda gets things running smooth, I'm going to take a small break from spending money. Playing around with the nitrous should last me for a couple months.

I figure, I'm going to have the truck for quite a while, so I really should slow down a bit on cramming money into it.

I'll probably see how much I can really get out of the 35 shot before I start moving up. I had the phone in my hand and ready to order the converter but I just couldn't part with the $834.75 just yet.

I think I'll probably spend a few bucks here and there on some NX accessories, like an electric bottle opener and so forth. Perhaps a transgo tranny kit (79.00). Stick with the less expensinve stuff for now. The converter will definately be the next big purchase, then I have to pay someone to install it too.

I figure, by the time I pay the truck off, I won't even recognize it. It will probably be either lowered or raised (haven't decided yet), custom paint, rims, tires, stereo, interior...etc. I'm not sure yet.

I definately want to get it down into the 14's before I call it quits with the motor and start dressing her up.

I'll photograph a time slip from the track on Friday night and post it in my picture gallery.

Take it easy. I gotta take the truck over to Steeda and drop it off so they can get working on it.

Tom.

 

Man $800 for a torque converter? I can see why you would do a shift kit first. Sheeew. Later

 

Ah Taylor, you win NO prize today, sorry.

Got the truck back from Steeda. They inspected everything, then put my truck on the Dyno and said that they felt the same thing I felt and that the shaking was coming from, as I suspected, the freakin drive shaft.

So, as with many modifications, I need to now take it to Broward Powertrain and have my drive shaft either upgraded or balanced.

Another $250.00 bucks!!

Take that into consideration when your putting new gears in.

Bites.

Tom Longo

 

Well shucks no prize. I think maybe now my suggestion would be one of two things: go tell steeda to fix your driveshaft as one of the employees must have dropped the thing or somehting. Truck runs good=steeda installs gears=truck has vibration, did they try and tell you that the gears you had installed needed a different driveshaft? My next suggestion would be take it back to the dealer with only 3500 miles who cares let them fix it. Let me know what you find out. So I don't suppose your gonna get to run it then huh? Later

 

This is probably kind of silly but I've done it on mine and a buddies to fix a vibration. This is on older trucks so it probably won't help you but may help someone else. When a U-joint has been removed a bunch of times sometimes the installer does'nt get it back in the saddle of the yoke just right. When he cranks the u-bolts down it can deform the alignment stops for the u=joint. I had a vibration in mine after my AOD swap. Took the u-joint down and sure enough you could see that it was off center about 1/32nd or so. Reset it after cleaning it up with a file and no more vibrations
Clint

 

Now that sounds like a very good piece of advice.

 

Do I get a prize? lol. Been driving and tooling on my truck for 23 years so if something could be screwed up on it I've probably done it. lol
Clint

 

I guess we will have to see if you get a prize or not depending on the final culprit. haha. later

 

tomlongo
Iwas wondering what you found out?