need info on cobra transmission

[svtdriven]

I believe my stock trans has a bent input shaft. the shifter vibrates at 65+ mph. but on more aggressive acceleration from a stop, the vibration isn't there until I let off the gas and resume cruising speeds.

I have 3 options.

1. The trans has 110k miles on it. I am thinking about rebuilding it myself. just get a new input shaft, rebuilt kit with syncros, throw out bearing, and some detailed instructions and going for it.

2. I have a spare t45 with under 30k out of a 99 cobra. As far as I know, I'd need an input shaft, my current bell housing, and possibly a new cross member. might be the cheapest route to go.

3. just replace it with another t5, low mileage used or a rebuilt one.

the car is a summer weekend driver, and even when the supecharger is installed, I don't think I'll be hard enough on the car to break the trans. So I don't think a tko trans is going to be worth it for me.

what would you recommend?

 

[LEE93COBRA]

I would check the u-joints in the driveshaft. If you had a bent input shaft, you would have a lot more serious issues then a vibrating shifter. Do you have an aluminum driveshaft? Do you have different gears then what came from the factory?

A t-45 will not work in a 5.0 for many reasons. But to touch on something you mentioned, you cannot remove the bellhousing from a t-45. It is part of the case.

If you are 100% sure that the vibration is from the tranny and not from something else, I would look into tearing it down and inspecting it. Only tackle the build if you have access to press.

Hanlon Motorsports has an awesome video on how to rebuild a t-5

 

[svtdriven]

Thanks for the response. it has the stock driveshaft and 3.73 gears. I admit, I did not check the u-joints. I will look into that before I do anything else. How will I know it is the u-joints? excessive slop?

 

[BADBOYSPACK]

Put the car on jack stands, let the clutch out in 2nd, and take a look.

You should be able to see it.

 

[Iggy347]

I had the same problem....espically when I let off the gas and crused. I replaced the U-joints but the problem was still there. I ended up buying an alum. drive shaft and the problem went away. :beer:

 

[PJM99]

Can you get rebuild kits for the T-5 in our cars? We have the super duty or heavy duty T-5 with some sort of coating right? The only rebuild kits I've seen look to be for regular T-5. Like this kit in Summit.......

http://store.summitracing.com/partd...4294842555+4294908282+4294908395&autoview=sku

 

[BADBOYSPACK]

I had the same problem....espically when I let off the gas and crused. I replaced the U-joints but the problem was still there. I ended up buying an alum. drive shaft and the problem went away. :beer:

Why didnt you just index the driveshaft ????

Would have saved your self a pretty penny.

 

[blueSHAKER]

If it's that bad you can jack the car up with both back wheels off of the ground while leaving the car in neutral (don't forget the jack stands...LOL), crawl under it and grab the driveshaft with both hands and quickly twist it back and forth to feel for slack in the u-joints if that is indeed the problem.

Listen for a bit of a clang when you disengauge the clutch while backing up too. Backing the car up will change the slack in the driveshaft to the opposite resting place if they are bad and you can usually hear it if you listen for it. Seems unlikely to me that it's a bent input shaft.

Rocks also have a way of kicking up under there too and dinging the driveshaft up knocking it out of balance so I'd do a little visiaul inspection while I was under there also.

You could check the axle bearings too I guess.

blueSHAKER

 

[svtdriven]

I never heard a clunk going into reverse. It's going to be 50º on sunday, so I will pull the car out and see what's what.

I neve considered the driveshaft to be bent since the shifter didn't vibrate under load from a stop. I figured that a bent shaft would vibrate all the time. I also had the rear bearings go bad in my 98, you could hear them grinding. I don't hear anything like that in the 93.

I am going to be doing a rear main seal, throw out bearing, clutch, and flywheel replacement here soon anyway. I might as well have the driveshaft checked, and replace all the joints and bearings too while I am at it. I also was thinking of getting an aluminum driveshaft. they are pricey though, haven't decided for sure on that yet.

 

[blueSHAKER]

You don't NEED an aluminum drive shaft if you don't want one (although it is well known that lower rotating mass - less weight - equals more HP). Your local driveshaft shop can cut the ends off of yours, insert a new tube, and balance it for you (If needed). I've had a few done this way with some of my older cars.

Have them check the balance on it first. That will be the best (and cheapest) way to answer that question. They may even be able just to rebalance yours if it's not too bad.

blueSHAKER

 

[SVT1993]

I also was thinking of getting an aluminum driveshaft. they are pricey though, haven't decided for sure on that yet.

The Aluminum Driveshafts are great, but you definately feel more of the "driveshaft" than in a stock unit. The stock unit provides for dampening of a lot of vibrations.

 

[blueSHAKER]

Yup...most of the Ford driveshafts have the rubber inserts around the yolk (like a harmonic balancer) that helps to keep the vibration in tact. That's why I like to have the yolks cut off and welded onto a new tube (if the old one is bent up) and then rebalanced.

blueSHAKER

 

[BADBOYSPACK]

Yup...most of the Ford driveshafts have the rubber inserts around the yolk (like a harmonic balancer) that helps to keep the vibration in tact. That's why I like to have the yolks cut off and welded onto a new tube (if the old one is bent up) and then rebalanced.

blueSHAKER

The rubber insert and the weight due alot for this condition.

I personally would do the aluminum driveshaft.