View Full Version : Someone wanna measure something for me?


anesthes
11-25-2011, 08:05:45 PM
If you have your car on jack stands, or a lift.

From the back of the block, where the bell housing/trans mounts, to the machined FACE of the snout on the rear differential (behind the dust cover on the yoke) I have 81".

I feel like Its an inch closer (causing a potential driveshaft issue if my suspension completely compresses) than it should be.

I'd love to hear from one or two other guys.

-- Joe

Rene Melten
11-25-2011, 09:43:19 PM
From your instructions mine measures 82". B/W ST-10, 48" drive shaft, center of yoke to center of yoke..

anesthes
11-25-2011, 09:49:22 PM
From your instructions mine measures 82". B/W ST-10, 48" drive shaft, center of yoke to center of yoke..

Thanks!

So my engine/front frame is 1" too far back, or my rear end is 1" too far forward.

If I check one or two more spots, do you think you could check yours for me and report back the measurement found? At this point I'm guessing the front frame is too far back, but there is also a good chance the pins are sheared and the rear end is too far forward. ?

-- Joe

mildthing
11-25-2011, 09:52:26 PM
I'm not sure that full-compression is the worry. If the front half of the rear springs is truly horizontal at ride height, then yes. Otherwise, the worry is at full droop.
I can check for that 81" or 82" late tomorrow afternoon.

Rene Melten
11-25-2011, 10:02:07 PM
Thanks!

So my engine/front frame is 1" too far back, or my rear end is 1" too far forward.

If I check one or two more spots, do you think you could check yours for me and report back the measurement found? At this point I'm guessing the front frame is too far back, but there is also a good chance the pins are sheared and the rear end is too far forward. ?

-- Joe
Yup, just ask what you want measured.

anesthes
11-25-2011, 10:23:50 PM
Yup, just ask what you want measured.

Thank you!

Here is the first one. What I did was on the bracket for the leaf spring, I guess the mount bracket, I took the rear bolt and measured from the center of that bolt to the axle tube. I get 20 1/2"

http://members.cisdi.com/~anesthes/frame_measure/spring_mount_to_tube_mod.jpg

That, I hope will at least tell me if my axle is in the right spot in relation to the leaf spring.

Next, I wanted to see if my front subframe is too far back, so I looked at the side of it and there is these like 1" holes. I put the tape measure in the most rearward hole, and measured to the eye of the leaf spring and I got 37 1/2"

http://members.cisdi.com/~anesthes/frame_measure/subframe_spring_eye_mod.jpg

Thank you!

-- Joe

Rene Melten
11-25-2011, 10:49:50 PM
I think we found it. Again with your pics. I got 21 1/2" and 38 1/2".

BondoSpecial
11-25-2011, 10:53:27 PM
My 79 measures about 5/8" off everyone else's cars in that dimension, although mine is too long, and my subframe is in perfect alignment and my rear is on the dowel pins of the new leaf springs. Chalk it up to build quality. I had to have a custom D-shaft made for what should have been a straightforward swap.

Rene Melten
11-25-2011, 10:57:22 PM
Hold on, I'll remeasure that 20 1/2" again, was a little confused, you said bolt! Be right back.

anesthes
11-25-2011, 11:00:07 PM
My 79 measures about 5/8" off everyone else's cars in that dimension, although mine is too long, and my subframe is in perfect alignment and my rear is on the dowel pins of the new leaf springs. Chalk it up to build quality. I had to have a custom D-shaft made for what should have been a straightforward swap.

Did you see my T5 swap thread?

http://members.cisdi.com/~anesthes/projects/t5_swap_2ndgen/driveshaft.jpg

This no look right...

-- Joe

Rene Melten
11-25-2011, 11:02:30 PM
Can't find a 20 1/2" measurement.

BondoSpecial
11-25-2011, 11:02:59 PM
I did. Like me, you have a custom driveshaft in your future. The 45.5'er did not work for me even though it should have.

Rumpity_z28
11-25-2011, 11:06:57 PM
your rocker panels are identical to the girlfriends car that im working on right now. Car was painted burgandy over blue and they didnt get the bottoms haha, i almost thought someone stole the car for a second

anesthes
11-25-2011, 11:10:36 PM
Can't find a 20 1/2" measurement.

Hrmm.

So from this bolt:

http://members.cisdi.com/~anesthes/frame_measure/mount_bolt.png

to the tube, what do you get?

Thanks!

-- Joe

anesthes
11-25-2011, 11:11:22 PM
your rocker panels are identical to the girlfriends car that im working on right now. Car was painted burgandy over blue and they didnt get the bottoms haha, i almost thought someone stole the car for a second

I'm too lazy to get on my knees when I paint. ;)

-- Joe

anesthes
11-25-2011, 11:14:10 PM
I did. Like me, you have a custom driveshaft in your future. The 45.5'er did not work for me even though it should have.

Your problem was the shaft was too short?

I was trying to find your original post before the whole bad shop welding job and couldn't find it.

Worst case scenario, I'll just put the yoke in a lathe and cut an inch back, and an inch off the splined portion. But I'd like to know where and why my car is this far off. We know the distance between the block and the front of the differential is not right, and I'd like to know where the problem is especially since I'm going to be starting that project you tried talking me out of soon ;)

-- Joe

Rene Melten
11-25-2011, 11:17:15 PM
Hrmm.

So from this bolt:

http://members.cisdi.com/~anesthes/frame_measure/mount_bolt.png

to the tube, what do you get?

Thanks!

-- Joe

22 1/2" center to center.

Edit, I have welded sfc's and they have been on the car for eons.

anesthes
11-25-2011, 11:32:15 PM
22 1/2" center to center.

Well I get 22" center to center. So there is a half inch.

I bet I'm a half inch or so out on the front frame as well.

Hey, thanks a lot, I appreciate it! I'll have to see if I can correct this.

-- Joe

Rene Melten
11-25-2011, 11:35:46 PM
Well I get 22" center to center. So there is a half inch.

I bet I'm a half inch or so out on the front frame as well.

Hey, thanks a lot, I appreciate it! I'll have to see if I can correct this.

-- Joe
Not a problem, anytime.

mildthing
11-27-2011, 12:30:51 AM
Sorry I wasn't able to give you my measurements yet, for further confirmation. Something came up, but I will measure Monday.

mildthing
11-29-2011, 05:43:34 PM
Okay, as per the pics, I got 21.625", 37.75" and couldn't check for 81" vs 82", sorry. This is on an '81 'bird

BondoSpecial
11-29-2011, 06:06:03 PM
Your problem was the shaft was too short?

Yeah. I had my aluminum shaft custom made to around 45.9" instead of 45.5". My subframe and leafs are all on fresh bushings and lined up properly. That's just the way the build quality crumbles w/ mine. I wouldn't get too hung up on theoretical shaft length if you get the subframe in position and you still are way off.

anesthes
11-29-2011, 06:41:24 PM
Yeah. I had my aluminum shaft custom made to around 45.9" instead of 45.5". My subframe and leafs are all on fresh bushings and lined up properly. That's just the way the build quality crumbles w/ mine. I wouldn't get too hung up on theoretical shaft length if you get the subframe in position and you still are way off.

It costs $65 to get the shaft cut down and rebalanced, so that will be done once I straighten the frame deal out.

I unbolted the subframe connectors tonight, and I ordered the solid mounts. Once they come in I'll position the subframe properly, and weld the connectors in (4 tires on ground).

I'm surprised you bothered making the shaft longer. The slip yoke, mine anyway, is almost 5 inches long... The slip yoke I have from am '87 Corvette/700R4 is half that length, so it appears having yours hang out over the recommended 3/4-1" wouldn't cause any issues.. ?


I wish I had known this car was as molested as it is when I bought it, or before I bought it for that matter.


-- Joe

anesthes
11-29-2011, 06:43:51 PM
Okay, as per the pics, I got 21.625", 37.75" and couldn't check for 81" vs 82", sorry. This is on an '81 'bird

Thank you. I know my subframe needs to slide forward a bit. Will correct that.

I'll still have the driveshaft shortened, and re-balanced.

-- Joe

BondoSpecial
11-29-2011, 06:44:58 PM
Why is your slip yoke so long? It should be the same super short TH350/700R4 shaft from anything else. I mocked up the slip yoke in a tailshaft off the car and noted that at 1/2" too short the yoke was almost pulling out of the bushing. Being more than .25" off target length with these short slip yokes is a big problem.

To quote an extremely wise man (me)

http://www.nastyz28.com/forum/showpost.php?p=2283806&postcount=7

The barrel on your yoke should only be 3.5" long which means you should have about 2.5" in the trans with the correct length shaft. The bushing itself is about 1" inset in the tail so that does not leave you with too much room for error in shaft length if you err in the too-short direction. If you err in the too long direction you're just risking bottoming it out and breaking driveline stuff.

anesthes
11-29-2011, 07:17:23 PM
Why is your slip yoke so long? It should be the same super short TH350/700R4 shaft from anything else. I mocked up the slip yoke in a tailshaft off the car and noted that at 1/2" too short the yoke was almost pulling out of the bushing. Being more than .25" off target length with these short slip yokes is a big problem.

To quote an extremely wise man (me)

http://www.nastyz28.com/forum/showpost.php?p=2283806&postcount=7

The barrel on your yoke should only be 3.5" long which means you should have about 2.5" in the trans with the correct length shaft. The bushing itself is about 1" inset in the tail so that does not leave you with too much room for error in shaft length if you err in the too-short direction. If you err in the too long direction you're just risking bottoming it out and breaking driveline stuff.

I'll take the shaft back out in a bit and re-measure it. I'm pretty sure it's darn long...

BTW, I checked my side to side clearance in the tunnel. I can't get my finger between the yoke and the support brace in the tunnel on the right side. On the left side I can get 3 fingers in.

Seems like an excessive bias to the right...

-- Joe

BondoSpecial
11-29-2011, 07:20:35 PM
If your yoke is longer than that one, it's the wrong yoke. There is only one TH350/700R4 yoke for a 3R joint. They make different length ones for 1310, 1330, etc joints and if you somehow have that, you are going to have problems.

anesthes
11-29-2011, 07:58:59 PM
If your yoke is longer than that one, it's the wrong yoke. There is only one TH350/700R4 yoke for a 3R joint. They make different length ones for 1310, 1330, etc joints and if you somehow have that, you are going to have problems.

I was wrong, not quite 5" but 4", maybe 4 -1/8".


OK. I have two yokes from 2nd gens - the yoke from my '79 Z28 (pictured below), and one out of an '80 camaro with a TH350. They are the exact same length.

http://members.cisdi.com/~anesthes/frame_measure/79_camaro_yoke.jpg

Next, this is a stock yoke from an '87 Corvette with a 700R4. I took it out of my vette when I swapped to a ZF6 transmission. Notice it is shorter, and much less is in the transmission. I don't know what ujoint it takes, but it had the e-clip on the OUTSIDE vs my TH350 Camaro yoke which had no clips on the stock ujoint (guy forgot?) but did on my conversion ujoints.

http://members.cisdi.com/~anesthes/frame_measure/87_vette_yoke.jpg

Notice the rust mark showing how much is inserted into the transmission. Looks like just about 2 1/4".

Look at the rust mark on my Th350 yoke, looks like it is inserted about 3 inches and has a little ride in and out.

If this is the same yoke you have (vs a thirdgen camaro yoke, which is around the same size as a vette yoke if I recall), you would have still had plenty of yoke inside the trans I think.

edit: google says an '87 vette driveshaft is a 1310 ujoint.

-- Joe

BondoSpecial
11-29-2011, 08:29:31 PM
If you didnt' measure the fillet or the tapered end that's a 3.5" barrel so that's the correct yoke. Like I said the bushing in the tail is almost 1" inset so there is not that much room to play with for slip travel, I checked it on mine when the shaft was too short and it came really close to where the end of the yoke towards the front of the car would start pulling out of the bushing such that you didn't have 100% support anymore. These slip yokes are mega short compared to like a Mopar 727 yoke...THOSE are long yokes.

anesthes
11-29-2011, 08:32:53 PM
If you didnt' measure the fillet or the tapered end that's a 3.5" barrel so that's the correct yoke. Like I said the bushing in the tail is almost 1" inset so there is not that much room to play with for slip travel, I checked it on mine when the shaft was too short and it came really close to where the end of the yoke towards the front of the car would start pulling out of the bushing such that you didn't have 100% support anymore. These slip yokes are mega short compared to like a Mopar 727 yoke...THOSE are long yokes.

I think something just dawned on me.

If you look at that corvette yoke, it has a press fit weight or something on it (the ring where I wrote '87 vette). The vette yoke takes a 1310 ujoint same as the fox body shaft. If I take that ring off, and stick the yoke in the lathe and make sure the surface is true I'll get my 3/4"+ I need... Won't have to take a trip to the driveshaft shop.

-- Joe

BondoSpecial
11-29-2011, 08:34:24 PM
That might work for length (that's a torsional damper on there by the way). However you still need to rebalance even just changing the yoke. Been there, done that, had vibrations.

anesthes
11-29-2011, 08:46:35 PM
That might work for length (that's a torsional damper on there by the way). However you still need to rebalance even just changing the yoke. Been there, done that, had vibrations.

The driveshaft is balanced to the yoke? That is absurd, why wouldn't both be neutral!?


-- Joe

mildthing
11-29-2011, 09:28:08 PM
The driveshaft is balanced to the yoke? That is absurd, why wouldn't both be neutral!?


-- Joe

Casting variations, production tolerances, et cetera.
I used to work in a shop that did driveshafts. If the tolerances stack, it can really create imbalances you can feel by 55 MPH.
The weld yokes at either end of the tube itself, those usually don't weld in perfectly square and true, either from the car manufacturers, or the guy who was my boss, who had 20 years experience.
Ideally, you'd have the pinion yoke on the shaft for balancing before assembling the rear axle. We had a selection of pinion yokes, from the Ford 8" and the GM 7.5", to big-rig 18-wheeler sizes, and you should have seen some of the weights we had to use just to get those neutral.
The bigger number your rear axle ratio, and the shorter your rear tires, and the more MPH you're going, the more critical the balance gets.

anesthes
11-29-2011, 09:31:15 PM
Casting variations, production tolerances, et cetera.
I used to work in a shop that did driveshafts. If the tolerances stack, it can really create imbalances you can feel by 55 MPH.
The weld yokes at either end of the tube itself, those usually don't weld in perfectly square and true, either from the car manufacturers, or the guy who was my boss, who had 20 years experience.
Ideally, you'd have the pinion yoke on the shaft for balancing before assembling the rear axle. We had a selection of pinion yokes, from the Ford 8" and the GM 7.5", to big-rig 18-wheeler sizes, and you should have seen some of the weights we had to use just to get those neutral.
The bigger number your rear axle, and the shorter your rear tires, and the more MPH you're going, the more critical the balance gets.

Hrmm. Interesting. So you are recommending I remove the pinion yoke off the rear diff and bring that with it for total balance?

-- Joe

mildthing
11-29-2011, 09:33:10 PM
I was wrong, not quite 5" but 4", maybe 4 -1/8".


OK. I have two yokes from 2nd gens - the yoke from my '79 Z28 (pictured below), and one out of an '80 camaro with a TH350. They are the exact same length.

http://members.cisdi.com/~anesthes/frame_measure/79_camaro_yoke.jpg

Next, this is a stock yoke from an '87 Corvette with a 700R4. I took it out of my vette when I swapped to a ZF6 transmission. Notice it is shorter, and much less is in the transmission. I don't know what ujoint it takes, but it had the e-clip on the OUTSIDE vs my TH350 Camaro yoke which had no clips on the stock ujoint (guy forgot?) but did on my conversion ujoints.

http://members.cisdi.com/~anesthes/frame_measure/87_vette_yoke.jpg

Notice the rust mark showing how much is inserted into the transmission. Looks like just about 2 1/4".

Look at the rust mark on my Th350 yoke, looks like it is inserted about 3 inches and has a little ride in and out.

If this is the same yoke you have (vs a thirdgen camaro yoke, which is around the same size as a vette yoke if I recall), you would have still had plenty of yoke inside the trans I think.

edit: google says an '87 vette driveshaft is a 1310 ujoint.

-- Joe
At normal cruise, the slip yoke should be 1" from bottomed into the trans.
Pull it out just 1/2" more, you'll get weird harmonics you can hear, like on the interstate, and traffic-light-clunking you hear and feel. If you have to convert to a 1330 just to get a 1/2"-longer slip yoke, it's still cheaper than re-tubing the driveshaft longer, then balancing.
But the re-tube gives you the option of upgrading from 0.065"-wall to 0.083" or 0.095", and if you're 2.75" tube, you can easily go 3", which helps more with higher driveshaft speeds.
Going 3.5" takes new weld yokes, so then you go 1350 series. More cost. You can get 3" 1350 if appropriate to your app.

mildthing
11-29-2011, 09:35:10 PM
Hrmm. Interesting. So you are recommending I remove the pinion yoke off the rear diff and bring that with it for total balance?

-- Joe

Yes, but then you're doing a crush sleeve, and a new pinion nut. But you can do a new pinion seal and check the bearings.
Also, you then need to stamp the shaft yoke and the pinion yoke for which way they clock, or you might get it 180 off and have to crawl back under after your first test-drive.

BondoSpecial
11-29-2011, 09:43:13 PM
That is absurd, why wouldn't both be neutral!?

Look at the yoke. It's a rough cast, irregular piece of metal with no drill holes. It's not neutral balanced itself. It will be a huge contributor to shaft imbalance. Technically even changing u joints will have a small but measurable effect on balance. The yoke is a large % of the mass of the whole assy.

Todd80Z28
11-29-2011, 10:03:08 PM
One important point about the Corvette yoke- it may be shorter because it doesn't move. Corvette has IRS, so the rear diff is stationary. Our yokes have to slide, a little at least.
I do like the damper though... hmm...:)

anesthes
11-30-2011, 09:26:12 AM
Spoke to the driveshaft shop again. They said bring it in with the slip yoke and ujoints, not the pinion yoke. They said those are neutral from the factory and don't get balanced into the equation.

*shrug*

-- Joe

mildthing
11-30-2011, 09:32:03 AM
No, they are not neutral from the factory.
The mass of the pinion housing, and the preload on the crush sleeve, together mask most of the imbalance of the pinion yoke.
The concern here is trusting them. Are they even set up to balance with the pinion yoke? Do they have a neutral yoke of their own? If both answers are no, then it's certainly the wrong shop.

anesthes
11-30-2011, 09:41:22 AM
No, they are not neutral from the factory.
The mass of the pinion housing, and the preload on the crush sleeve, together mask most of the imbalance of the pinion yoke.
The concern here is trusting them. Are they even set up to balance with the pinion yoke? Do they have a neutral yoke of their own? If both answers are no, then it's certainly the wrong shop.

Dunno. They are a driveshaft shop only.

Denny's driveshaft said the same thing.

-- Joe

anesthes
11-30-2011, 09:48:19 AM
Just spoke with action machine, where Bondospecial got his done and they said the same thing.

-- Joe

mildthing
11-30-2011, 09:57:55 AM
It's fine to leave the pinion yoke off if the shop has their own. But if they don't, then they're just clamping 3 rollers around the rear of the shaft, so the rear joint wrongly gets left out of the equation. Not good.
We never asked the normal stuff to bring pinion yokes. But the guys with serious race cars always brought pinion yokes without being asked.

anesthes
11-30-2011, 10:25:37 AM
It's fine to leave the pinion yoke off if the shop has their own. But if they don't, then they're just clamping 3 rollers around the rear of the shaft, so the rear joint wrongly gets left out of the equation. Not good.
We never asked the normal stuff to bring pinion yokes. But the guys with serious race cars always brought pinion yokes without being asked.

Hrmm. Well they all told me they don't need it, however I didn't ask what they used instead of it.

I guess I'll try it. If it shakes, I'll try another shop.

I gotta align my front subframe, then lower the car on stands to load the suspension and see how much I need to have removed from the DS.

-- Joe