i recieved a set of mancini xhd leaf springs (springs have 1" added to stock arch). after i installed them i started getting a sound similar to the one described in other post about pinion angle. since i've never heard this sound before in the 8 years i've owned the car i concluded that it must be a result of the new springs.

I took some measurments today and found the rear u-joint is at +2deg, and the driveshaft is at +5. (i rolled the car to turn the driveshaft until the cap of the u joint was facing down and i made sure it was level)

measurments up front at the transmission u-joint was 0 and the driveshaft was at 0 as well.

The stock pinion snubber is 4" away from the car. (if that information helps any)

shims are needed to correct the angle? but what degree of shims?

or am i looking at this problem all wrong?

the transmission mount is probably the stock one, i stuck my fingers up there and it had a decent amount of rubber still there. if the mount is bad then that would throw the whole thing off?

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70 Plymouth Valiant 4dr

Pinion angle is the difference between the angle of the flat on the yoke (as you checked) and the angle of the transmission. (measured off the bottom of the pan or flattest part of the case for a stick)

You want the pinion 3 or 4 down from the trans.

Yes, a bad mount will change it.

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Official Cookie and Mater Tormentor.

transmission from pan was at a 1deg difference from the flat of the yoke. i'm going to buy a new transmission mount and then measure to see if that fixes it. (tranny mount is cheaper than shims). I'll keep you posted on what happens.

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70 Plymouth Valiant 4dr

I would measure trans angle by sliding in your slip yoke and using that to find the angle. Pan would only work if not dented at all, and might give some error even then.

Lou

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Home of Slant6-powered fun machines since 1988

thanks lou. put the new transmission mount in and measured again. measuring off the yoke i got +7deg on the transmission. the rear u-joint is at 0deg. i bought some 4deg shims and plan on installing them fat side toward rear of car, which would give me -4deg.

i inspected the u-joints and they both look decent. i tried to shake the driveshaft with my hands to see if there was any play in there and they held tight. i was thinking of perhaps installing new u-joints after i put the shims in. napa? Autozone Duralast? summit? i'm still new at deciphering which parts are american made and which are Chinese cheap.

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70 Plymouth Valiant 4dr

If you want good parts, you simply need to pay more for them. There is no way around this, I'm afraid.

If you want pay cheap, you will get junk, but of course it will not be advertised as junk.

Unfortunately, this buying habit has made it so that it is difficult to actually get quality parts for more $$.

I remember paying $10-15 for a good U-joint in 1988. There is no way you can make as good a part 23 yrs later for the same price. Now I look for the ones that are at least $20 and I will gladly pay $30 for something of known good quality.

Lou

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Home of Slant6-powered fun machines since 1988

Correct me if I'm wrong here, (I do confuse easily) but you are at +7 and 0. That is -7 on the pinion now. Putting the shims in with the thick side back will give you -11 wouldn't it?

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Official Cookie and Mater Tormentor.

slantzilla,
i did some google searching, and boy, theres a lot going on out there in regards to pinion angle.

i read the Car Craft article (http://www.carcraft.com/howto/91758/index.html) and towards the bottom under "Setting Pinion Angle" the second paragraph (from my understanding) says that the numbers should always be equal but opposite

i don't know how reliable that sounds, but i also stumbled across this picture: http://www.ssz28.com/tech/images/Pinion%20Angle/2.jpg
i'll tell you, there was many a night where i'm laying in bed starring at the wall trying to figure this one out in my head, usually while my girlfriend was talking about her new african drumming class.

but by god man you are right. that does make sense. if i tilt the rear axle lower, that would put it at an even greater distance from the tranny. if i tilt it up, the difference between them would be 3deg, which is what we're aiming for correct?
i'm still learning, forgive me wise men.

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70 Plymouth Valiant 4dr

If you realy want to have fun, go to Moparts and ask about pinion angle in the Race section. The discussions there have been epic.

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Official Cookie and Mater Tormentor.

not to highjack, but what if you used an adjustable pinion snubber, ran that all the way the floor board to minimize axle wrap along with a set of caltracs, and had trans and rear at 0 deg, a perfectly straight line for drag porposes only, good or bad idea ??

-Mike

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I am the Guardian, I hate helos, everything leaks.......

You want the angles equal but oposit. As the u-joint rotates it varies the rotation speed, if the angles are equal but oposit they cancel out the speed differences, however if they are not close to equal the drive shaft tries to speed up and slow down the diff twice each rotation.

Hope this helps

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Dave

1977 d-200 crew cab ex-army pickup wants it's /6 back
1962 Valiant 2 door, 170, three on the tree
1972 d-100 parts truck
80 volare wagon now a parts car

If you have Cal-Tracs a snubber is not necessary. (You use Cal-Tracs to get away from that useless snubber anyway)

Theory is you have to have some pinion angle or the bearings will not rotate in the U-joint caps.

Too much or too little and you get vibrations, wear, and breakage issues.

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Official Cookie and Mater Tormentor.

oy vey.

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70 Plymouth Valiant 4dr

Slantzilla

guess what?

i put those 4deg shims in today (thick side towards rear of car).
sounds like it's the "enola gay" getting ready for take off going down the road. vibrations. oh. so bad.

tomorrow i will flip the shims around and let you know how the car turns out.

aye yai yai..

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70 Plymouth Valiant 4dr

What you got against the Enola Gay? Lotsa US history right there, it is.

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Official Cookie and Mater Tormentor.