Featured Technical T5 Swap Vibration Woes

I thought I’d share an update.

I pulled the trans today and measured the concentricity of the bellhousing to the crank. It was .017” out of center. For a T5, that’s a lot from my understanding. So far this is the closest thing I’ve found to a “smoking gun”

I’m trying to find some offset dowel pins in a 3/8” diameter. Does anyone have any recommendation on where to find them? I’ve been looking around, but haven’t had much luck.

 

Remove the factory dowels.
snug the bell up with washers on the bolts and tap it around with a mallet until it has no runout.
Tighten the bolts.
Drill locating holes through the bell and block and tap in some roll-pins.

Also while the T5 is out. Remove the tail-housing and check the driveshaft yoke into the rear bushing [without the main-shaft]
You are checking for binding of the yoke.

 

You might need to find a shop with a good lathe.

 

What size are the factory dowels? 3/8" is a little odd for offsets. 1/2" is pretty much the norm.

Sure a machine shop can make some up but it won't be cheap unless you have an in with a shop.

 

The dowels in these are 3/8".

They can both be made inside of a single shop labor hour.

 

Surprised the clutch would work with that much run out.

 

I thought the vibration was speed dependent not rpm dependent?
If it’s speed dependent I’d expect the problem is transmission output, driveshaft or rearend.
Given that you’ve had 3 different driveshaft’s with the same issue I would eliminate that.

this isn’t to say that the clutch and bellhousing alignment is t a problem, I just don’t think it’s the problem you are trying to solve.

 

The vibration will be the Mainshaft chattering

@kerl_brah needs to dismantle the trans and check the bearing on the mainshaft [that goes inside the input shaft]
T5 transmissions wear badly on the front of the mainshaft [a hardened repair bearing sleeve is a permanent fix]
EVERY T5 I've rebuilt needed this.


The wear on the tailhousing is usually a giveaway clue
The mainshaft cantilevers over the centre bearing and pushes downward as the main gears try to separate from the countershaft gears [with torque applied]
Usually the clue is a very slight whine in 1st and it gets slightly louder in 2nd and then 3rd .And the whine goes away in 4th.

That is why I asked if the T5 was overhauled in post #3

 

^^^^^
Well, I'm learning things in this thread. .
Thanks.
& MM;
The comments I made on bent shafts wasn't from power point of view, rather from an improper handling &/or careless shop-maneuver that results in a bent/damaged shaft. At least that's how my stuff got damaged back then. ;( . But thanks for the info. I'm guessing T5s aren't the best, but merely ok, in most situations? Not knocking here, serious Q.
Marcus...

 

It isn't a T5 fault , they are just an old transmission now.
Most people "rebuild" them by simply throwing a small parts kit at them.

They will check for end play, but never lateral play.

Wear on the mainshaft nose is also very common of Japanese truck [4 x 4] transmissions.
It is a very simple repair while the trans is apart.
This Mitsubishi 4 x 4 trans has a pressed on repair sleeve [arrow]


@kerl_brah one of the main symptoms of bellhousing misalignment is difficultly to engage 4th gear ,and sometimes popping out of 4th gear [direct 1:1]
I've had Toploader's and Muncie's do that, but the biggest culprit was stamped steel scattershields.
Usually a factory bellhousing is pretty good.
Before you dick around with the dowels, see if you can locate another bellhousing to test. also check your existing bellhousing for cracks or damage. [the car could have been in an accident sometime in the last 60 years]

 

Excellent advice everyone! The trans builder took the transmission apart today and measured runout on the lathe. The rear support bearing measured .006” runout. Considering the cantilever from the rear bearing to the output splines, I’d assume this is closer to .02-.025 at the output splines. This would likely be causing the damage I’m seeing to the yokes.

The clutch engagement was actually really nice, I never had any complaints about clutch feel or engine RPM dependent vibration.

 

I actually had a different bellhousing installed when I first did this swap and later swapped to my original bellhousing in the hopes to cure the issue.

You bring up a good point, the bellhousing swap made no difference in the vibration.

 

Don't forget about the adapter between the engine and the bellhousing .... yet another possible source of misalignment. Making an assumption here as I don't know the specifics of the Modern Driveline adapter.

 

Unfortunately I’m at a point in this 6 month struggle I need to throw in the towel. My patience and wallet have reached the end. If anyone wants a world class T5 or Maverick rear axle, please reach out. Located in Oregon

 

I understand, but must add; sorry to hear this. Could you wait abit, & hit it again in a couple weeks, maybe, to let the frustration burn down. I've been there - more than once. Hopefully, you can make it work out for you. Good luck.
Marcus...

 

Sounds like one of those folks who started out thinking " how hard can this be?"

 

We’ve all been there,
Best advice I can give is take a break from it, I assume this isn’t your daily driver, and come back to it when you’re feeling better about it.

these things can really consume you. It won’t hurt to leave the car on stands for a month and do whatever noncar people do with their spare time.

 

Can't say I'm shocked. Wouldn't it have been cheaper to simply have a second shop verify the first driveshaft was true and balanced rather than have three different ones made by three different shops?

 

He could've gone through the motions of checking the basics himself. [ it will be something stupid simple that was overlooked ]
Another thing I've witnessed in a T5 is the Yoke bottoming out.

The car needs jack stands under the axle tubes [so the suspension is at ride height] Then remove the Driveshaft from the Diff flange and see if it can slide forward an inch.
Most people miss this because the rear suspension is hanging when the driveshaft is installed.

The mainshaft of a T5 pokes out the rear more than on Muncie's or Toploader's so it gives the illusion that there is plenty of yoke travel.[when it could bottom out]

T56's are also like this. [this looks wrong, but it is actually correct]


If the yoke bottoms out "gently" it will put side load on the rear bushing, and cause vibrations.

We had this problem on a friends Chevy Pickup [Camaro T5 with Ford Tailhousing] but the solution was killing 2 birds with one stone.
We simply moved the whole axle rearward to fix the ugly wheel arch clearance/ wheelbase issue.

 

I feel for the guy. He had every reason to expect that things would work together(w/o 1st re-engineering/rebuilding/etc), more or less, since he paid for things that should've worked, & for work that was supposed to be properly corrective. & it wasn't. + the time & effort of assembling & tearing down, repeatedly, things that were again, supposed to be right. It really drags after awhile, as does the expense. Even *if* the re/re-fix isn't charged for again. Well, damn-howdy, might as well become machinists, tool-&-die-guys, foundry-guys, fill the garage full of equipment, & start makin' all our own adaptors, & everything else. I learned along time ago, to dry assemble things, then if that's ok, then to go thru checks/adjustments/corrections, since too many things can - & have been - f'd up in the past(& current) by others, wornout tooling &/or time & mistakes. But that also gets old... Hopefully, he doesn't *need* this car...
But there's alot to learn from this thread on what to check before ordering, & as you assemble. Good reminder(s).
Marcus...

 

It’s really not helpful to dog on the guy for trying something that should have worked and getting discouraged when things don’t work the way they should have.
As far as I can tell he did everything right,
unfortunately these days you can’t trust new parts anymore than used parts.
And not all of us are capable of testing everything in every way.

 

I’m sorry to say, but if you’re using parts that never came in that vehicle, you are in fact re- engineering that vehicle and you had best understand that and what’s involved to make everything work together

 

Honestly In many cases I'll trust a used part more than a new one. At least the used part hypothetically road tested good on a previous vehicle

 

Only sbf challenges I've had were the different wt crank balancers, and firing orders. Never seen a trans cause vibrations. Check built u-joints and driveshaft phase. (Sure mentioned many times) your driveline angles are good unless suspension is allowing rear rotation. Go Pro under it, see what's happening. My pops had a vibration ONCE from a bent rear hsg, evidently rear was in accident from salvage yard.

 

Three shops/three shafts suggests to me that the owner is too focused on what he assumes is the cause and is most likely not open to suggestions from people on this site as what he needs to do/check to hopefully locate the issue. It could literally be as simple as he forgot to install or installed the incorrect pilot bearing/bushing or the engine/trans isn't true to the centerline of the chassis or the pinion angle isn't being measured correctly etc etc etc.

Not really meaning to dog the guy but when you do something three times and the result is the same each time yet you were expecting something to change ... isn't that the definition of insanity

As Kerrynzl wrote, it could and probably is something simple that won't be found if the person has given up. The solution may just involve work and not a lot of expense plus, there are plenty here willing to guide him.

Don't just tell us your angles, explain to us how you are measuring them. If the engine/trans are in line with the centerline of the chassis (which I think he said they aren't), fix it don't shrug it off as being "that shouldn't be the cause as it's not off too much" etc ...

Troubleshooting can be time consuming but doesn't necessarily have to be expensive. With the correct guidance, this would probably be solved ... throwing in the towel means it won't be. After reading about the three drive shafts then the decision to quit, I wasn't surprised in the least.

Is it still "dogging him" if he's already given up?

 

Appreciate your words of sympathy and all of the advice you’ve offered.

This car had consistently been my daily driver prior to painting it and swapping in the T5. The hope was to be able to take longer trips to Idaho or Montana without revving the poor 6 to the moon. I’ve built a couple cars in the past and went through many reasonable checks. I’ve never run into a vibration issue like this, even in my 4x4’s. I did not expect the 3rd driveline to resolve my issue, but a few close friends of mine that are excellent mechanics looked over the car and double checked all my measurements (working angles, yoke parallelism, centerline of crank/trans, etc) recommended to have a brand new one made with a new tube. Aside from the indexing of the crank/trans, the only questionable measurement found was bearing runout on the main shaft. A new main shaft is $600 and I’m not even certain in that being the resolution. I was also working with the lead engineer at modern driveline to identify the problem and following his advice which I greatly appreciated. They are a fantastic company, I wouldn’t hesitate to buy from them again.

I do appreciate all of the help from the members here. You gave me a lot of advice that helped me troubleshoot. Im not one who likes throwing in the towel, so this may be temporary and I may come back to back to this in a few years. I just want to get behind the wheel again and have my dependable car back.

 

Lakewood used to sell offset dowels. They are one of the companies absorbed by Holley.

 

So......Does the car try to vibrate when you run it in gear without the driveshaft in place ? You can get plastic inserts cheaply to slip over the tailshaft and help keep the oil in. One other thing I have not heard addressed is the diameter of the driveshaft and if there is any dampening in it to prevent harmonics? Another thing is does the vibration happen in the lower gears as well as higher gears? If it only seems present at higher speeds, it seems probable that the problem is after the transmission.......because the eng/trans go thru the whole rpm range in each gear, BUT the rpm of the driveshaft does actually increase only as speed of the vehicle increases. Here is a very good video and the end of it shows that premise.
https://www.bing.com/videos/rivervi...813DDB7CCC72B875827F813DDB7CCC72B87&FORM=VIRE

Driveshaft Diameter Calculator
They say " Exceeding or approaching the lenght limit will cause vibration - even IF the driveline IS in perfect BALANCE !"

< See Dana's guide to safe operating RPMs. We recommend operating at one half critical speed.

Calculate Driveline Revolutions

 

A used main shaft can be had for as little as $180.