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140 Pinion Angle

Tfrasca

Tfrasca

Active member
Joined
Apr 20, 2015
Location
Ben Lomond, CA
My brand new T5z has all the same vibrations at cruise and decel that my old WC T5 did. The transmission is angled 5 degrees downward, and the differential is at 0 degrees. I have the stock 2 piece drive shaft.

Am I oversimplifying things to say that if I adjust my diff to point up 5 degrees (opposite the transmission) that my vibration issues will get better?

Or is there more to it with a 2 piece drive shaft?
 
The Tremec app is pretty neat. I used it to set up the 8.8 and one piece driveshaft in the 122. No vibrations at all. I was under the impression that you wanted your pinion angle to point up as much as your tailshaft points down. Maybe that’s for one-piece driveshafts. Pretty sure I set mine up at 4* and all is good.

Its been a while since I set up the 142 but I think I measured the downward angle of the rear section of the driveshaft and pulled the pinion angle up to match.
 
AndrewNance said:
The Tremec app is pretty neat. I used it to set up the 8.8 and one piece driveshaft in the 122. No vibrations at all. I was under the impression that you wanted your pinion angle to point up as much as your tailshaft points down. Maybe that?s for one-piece driveshafts. Pretty sure I set mine up at 4* and all is good.

Its been a while since I set up the 142 but I think I measured the downward angle of the rear section of the driveshaft and pulled the pinion angle up to match.
Click to expand...

That's what I was thinking of doing for this, but the 2-piece changes that, I think. I'm going to go measure the angles of both sections of driveline, then plug it all into the Spicer app and see how it looks.

Do you have T5s in either of those cars?
 
I took some measurements.

-Trans output points down 4.4*
-First driveline points down 1.7*
-Second points down .7*
-Pinion is at 0*

My operating angles are, from trans to pinion: 2.7, 1, and .7*

Spicer wants each end of a driveshaft to be within 1* of each other. If I can shim my trans mount to get the output shaft close to 3*, then make some adjustable torque rods and set my pinion to to around 2*, that should get all three operating angles pretty close to each other.

Unfortunately, the center support can't really be moved, so I'm stuck with the factory position.
 
If you're adjusting the pinion angle, consider dropping it down 1?-2? from the spec's to compensate for axle twist under acceleration.
 
For test purposes on the trans, you can shim it up via a spacer under the mount, down via spacers between the crossmember and frame, depending on what crossmember setup you have. I used the SN95 crossmember, so it's 4 vertical bolts. Might be a bit more hassle if you kept the 140 crossmember though.

Definitely need to get that front section addressed, probably a good bit of your vibration there.

Also take into account horizontal angles as well. Those angles are probably off on the front section, since the T5 doesn't sit centered in the tunnel like the M41's do.
 
hiperfauto said:
If you're adjusting the pinion angle, consider dropping it down 1?-2? from the spec's to compensate for axle twist under acceleration.
Click to expand...

Yeah, I plan to give it a bit of room to rotate up. I have no vibration under hard acceleration, so it's probably rotating up to a better angle under load as is.

gsellstr said:
For test purposes on the trans, you can shim it up via a spacer under the mount, down via spacers between the crossmember and frame, depending on what crossmember setup you have. I used the SN95 crossmember, so it's 4 vertical bolts. Might be a bit more hassle if you kept the 140 crossmember though.

Definitely need to get that front section addressed, probably a good bit of your vibration there.

Also take into account horizontal angles as well. Those angles are probably off on the front section, since the T5 doesn't sit centered in the tunnel like the M41's do.
Click to expand...

Yup, stock 140 crossmember, so I can't shim that down. But it seems like the trans would want to come up anyway. I already have a 10mm shim pushing the trans up, but any further and it'll probably start hitting the tunnel. I think my horizontal angles should be pretty good. My T5 slip yoke is pretty much dead center in the tunnel. I'll try to figure out how to measure that though.

My next move is adjustable torque rods. Does anyone know if the 240 ones are the same, just a different length? I'd rather not pull mine, cut them, measure the ID, then have to wait a week while I order the parts to weld up.
 
The 240 torque rods are different.

FYI, new torque rods are available for $66.00 each.

Although ride quality would suffer, you could make your own and use heim joint ends and spacers to center the heim joints. Both of the stock bolts for attaching the torque rods are 1/2" diameter.

I have good used torque rods too.

Tfrasca said:
My next move is adjustable torque rods. Does anyone know if the 240 ones are the same, just a different length? I'd rather not pull mine, cut them, measure the ID, then have to wait a week while I order the parts to weld up.
Click to expand...
 
Check Yoshifab. They are now offering adjustable torque rods for the 140 / 164. A little pricey; but, very trick looking. As mentioned, you could fabricate similar rods by using components from somebody like Speedway or you could modify your own rods to make them adjustable.

Be aware that heim / spherical joints are not the be all and end all. Unless sealed in a bellows, they can become noisy once they accumulate dust leading to some interesting noises during suspension movement.
 
I'd lengthen your stock ones personally, but that's just me.

For checking centerline, drop a string from the center of the crank pulley, another from the center of the pinion, then see where everything lines up along the way. I did that, put tape on the garage floor with a mark, then ran a string along that. I bet you will find your trans sits off to the passenger side a good bit compared to the center bearing.
 
Tfrasca said:
That's what I was thinking of doing for this, but the 2-piece changes that, I think. I'm going to go measure the angles of both sections of driveline, then plug it all into the Spicer app and see how it looks.

Do you have T5s in either of those cars?
Click to expand...

T5 in the 122. M41 in the 142.

I made some adjustable torque rods out of stock 122 rods after my heim joints left me wanting something...better. I actually used some adjusters I had bought for 240 torque rods but the ID was the same on the 122 ones. So I’m guessing they never changed that. I’m almost positive it’s 3/4” ID and accepts a 1/2x20 adjuster. I’m pretty sure I bought two of these pairs:

http://www.barnes4wd.com/Threaded-Tube-Inserts-For-12-20-TPI_c_181.html
 
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I went with the tractor pin route since they are fine thread, but also because I like the safety of knowing nothing can adjust itself unless one end of the arm comes completely off.
 
142 guy said:
Check Yoshifab. They are now offering adjustable torque rods for the 140 / 164. A little pricey; but, very trick looking. As mentioned, you could fabricate similar rods by using components from somebody like Speedway or you could modify your own rods to make them adjustable.

Be aware that heim / spherical joints are not the be all and end all. Unless sealed in a bellows, they can become noisy once they accumulate dust leading to some interesting noises during suspension movement.
Click to expand...

Yeah, I like those, but I'm not going to use any heim joints on this car. Too much NVH. I'll modify my stock ones and keep the rubber bushings.
 
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