87 drive shaft problem

[stroker87]

Hi every one!

I got my truck together start of this season then the tail housing on my 700r4 blew off 1/2 track, I let it sit for a while (to annoyed with it) last weekend I got it back together had the drive shaft balance (even though it didnt need it) bough a 700r4 to rob parts from, the guy who did the balancing asked me to measure from the trans output shaft to the yoke on the rear axle 58.5" when i told him that he said the drive shaft and slip yoke are .75" to short meaning the slip yoke does not go into the transmission enough and he is 100% right!

far as i know its the original drive shaft but i'm the 3rd owner so any thing is possible is there different length one peace drive shafts? I did lower the truck 2/4 spindles and shackle & hangers but never herd of any one having this problem

[geezer#99]

Did you measure it with the suspension loaded or on a hoist with the rear hanging?

[stroker87]

nope had the rear end on jack stands to keep it loaded

[geezer#99]

When you have the driveshaft installed, how much free play is there between the yoke and the tail housing?

[stroker87]

i have not measured it but probably 2.5" or so

[geezer#99]

So we need to assume your ds has always been like that. Possibly why you had the tailshaft problem.
I think they make longer yokes.
Ask the ds guy. He'll know what works.

[stroker87]

Originally Posted by geezer#99

Ask the ds guy. He'll know what works.

that was the 1st thing I did was ask him that, he just wants to sell me a custom drive shaft...... thats why i'm posting here to try and find out as much as I can

[geezer#99]

Depends what he wants to build you a new one. A yoke might be 100 bucks or more.

[stroker87]

he wants $300 for a new drive shaft? but I'd like to know if there is different size 1 peace drive shafts? different yokes or is there a way to just move the rear end forward an inch?

[geezer#99]

Sure there are longer ds. Longer yokes too. You could move the rear ahead but not the best idea.
Look here for different yokes. Measure yours then go from there.
http://www.dennysdriveshaft.com/c75_general_motors.html
Also info on there for proper measuring etc.

[Keith Seymore]

Originally Posted by stroker87

he wants $300 for a new drive shaft? but I'd like to know if there is different size 1 peace drive shafts? different yokes or is there a way to just move the rear end forward an inch?

There were dozens of different length one piece shafts in 1987.

Every cab length, box length and driveline configuration (practically) drove a unique part number.

K

[stroker87]

Originally Posted by Keith Seymore

There were dozens of different length one piece shafts in 1987.

Every cab length, box length and driveline configuration (practically) drove a unique part number.

K

I have a regular cab shot box, I was referring to my cab and wheel base sorry I guess I should of been more specific

I'm wondering if the the drive shaft in this truck was for a different transmission RCSB truck maybe an earlier year?

[Oldriginal86]

I have the same configuration, I could measure mine and post the length. Are you measuring u-joint cap center to center?

[stroker87]

yes if you can measure center to center of the u joints that be great!

thanks

[Keith Seymore]

Originally Posted by stroker87

I have a regular cab shot box, I was referring to my cab and wheel base sorry I guess I should of been more specific

I'm wondering if the the drive shaft in this truck was for a different transmission RCSB truck maybe an earlier year?

Probably.

What I was trying to convey was that there would be several different shafts required for a regular cab short box based on powertrain.

For example, my V6 manual might take a different shaft than a V6 auto, depending on which auto trans.

A 454 cu in THM400 equipped short box got a two piece shaft, for example.

There may have been close to a hundred different shaft part numbers to support the broad range of the portfolio.

I know the prop shaft design release engineer during the squarebody era (he was the release engineer when I was in driveline development). I asked him for an old release chart which he said he would give me, but he hasn't delivered yet.



K

[Oldriginal86]

Measured driveshaft. 55 1/4" from u-joint cap centers.

[stroker87]

Originally Posted by Oldriginal86

Measured driveshaft. 55 1/4" from u-joint cap centers.

tank you this will be a big help to know if I have the right shaft

Originally Posted by Keith Seymore

Probably.

What I was trying to convey was that there would be several different shafts required for a regular cab short box based on powertrain.

For example, my V6 manual might take a different shaft than a V6 auto, depending on which auto trans.

A 454 cu in THM400 equipped short box got a two piece shaft, for example.

There may have been close to a hundred different shaft part numbers to support the broad range of the portfolio.

ok gotcha know I under stand, thank for the input

if that chart shows up please fill me in

[stroker87]

my drive shaft is about 55.5"

this is how far the yoke is sticking out it about 1.75" is that normal? the yoke shaft is 3.75" long so there is 2" in the transmission

[50seven]

Stroker87 I read in your OP that you lowered the truck with shackles and hangers. I would look at this closely on a vehicle used for drag racing.

My concerns are pinion angle and axle wrap compounded with the extra shackles. If your truck is hooking up hard who knows what is going on back there? Check your wheelbase you may have altered it from stock (longer)?

I just lowered a truck axle over and the driveshaft needed to be shortened by 3/4"?

[stroker87]

Originally Posted by 50seven

I just lowered a truck axle over and the driveshaft needed to be shortened by 3/4"?

truck has 1.7x 60' so it does get up and go pretty decent, I installed a flip kit in my 2004 silverado and the kit is designed to move the axle back 1" to keep it alined where it suppose to be every one i talked to tell me the lower you go the more it move the rear end forward but in this case for some reason its .75" back? pinion angle was checked and its fine

trying to figure this out I don't want to blew another tail case or possibly trans

[50seven]

I would guess the axle flip kits lengthen the wheelbase beyond stock to avoid shortening the driveshaft. I didn't buy a kit I made my own perches and put the diff back where it is stock and shortened the driveshaft.

But with your truck I am thinking the combo of axle wrap, shackle movement and deformation under load is a concern. The longer the shackles length the more deformation and leverage under load. The longer shackles put in more movement and leverage on your leaf springs. One side loads up harder than the other. Dodge drag race teams used extra leafs on one side just for this situation and used short shackles. Check the center to Center on your wheelbase to see if that is where you lost the 3/4" in your case?

[stroker87]

I didnt loose (shorted) some how I gained (yoke is out .75")