drive shaft for lowered trucks

[mbl530]

Ok guys I'm 63 years old building my 1st square body, I have a 75 chevy long box I am building. I have a 5" drop with a Scotts's dropped cross member in the front. for the rear I bought 2" drop leafs springs from Eaton Detroit. along with a mcgauphys flip kit and C notch. So, 5 in the front, and a total of 8 in the rear. Here is my question. I am aware of pinion angle, I have a 2 piece drive shaft, and I have read that the carrier bearing bracket has to be shortened or moved up about 1.5 inches. Please educate me more on why this needs to be done. Is it so I can get the proper +/- pinion angle between tranny and rear end. I should add that This truck will ride on 20" wheels and tires. At my age I want this done right, it's a one shot only deal in my case. All work is being done by me, to include the body work and paint. So I will be asking a lot of questions, as this forum is a great tool. My motor was built by the Engine Factory 350 cu in 375 hp absolutely beautiful.

 

[J Knight]

Yes this mod is to correct pinion angle after drop, but honestly it would be much easier to just convert to a single drive shaft. Both LWB and SWB were optioned with 1 or 2 drive shafts.

 

[mbl530]

J Knight are single drive shafts still available from the dealers for a lwb 75 chevy.

 

[J Knight]

I doubt it, but the junk yards a littered with lwb squares. Im sure you should be able to find one or have one made for a $200-$300. What you need is a center u-joint to center u-joint measurement. Slide your yoke in the transmission until it bottoms out, then slide it beck out 3/4in, then measure the center u-joint cap to center u-joint cap where it will be on the rear end yoke.

 

[mbl530]

Thank you J Knight, I will probably have one made, 1 piece, and do away with the two piece, so what you are saying is the center carrier bearing is done away with?

 

[J Knight]

Thank you J Knight, I will probably have one made, 1 piece, and do away with the two piece, so what you are saying is the center carrier bearing is done away with?

Yes sir, just one shaft. Throw the whole carrier in the trash or save it in your shed.

 

[mbl530]

Got ya, J Knight. My yoke is not a slip on, it's a bolt on. I forgot to mention it is a th400. I need to mention that if I have one made, because I believe the th 400 uses a 1350 u bolt, instead of the 1310 or 1330 ujoints, correct me if I'm wrong.

 

[J Knight]

Got ya, J Knight. My yoke is not a slip on, it's a bolt on. I forgot to mention it is a th400. I need to mention that if I have one made, because I believe the th 400 uses a 1350 u bolt, instead of the 1310 or 1330 ujoints, correct me if I'm wrong.

Ok, well that's a problem, you can't run a traditional drive
shaft with a bolt on trans yoke and I am not sure if you can easily convert your TH400 to a regular tail shaft with slip on yoke. We may need @HRPC to answer this yoke delima.

 

[mbl530]

J Knight what or who is HRPC, remember I am new at this.

 

[ScottyB]

J Knight what or who is HRPC, remember I am new at this.

@HotRodPC You have someone wanting to talk to you.

 

[HotRodPC]

I guess I misssed the first mentioned.

Yes, You can indeed use the Slip yoke on the the threaded bolt on output shaft. Just unbolt the bolt on yoke, slide it out and now you're ready for the slip yoke. You can use the threaded bolt on output shaft for both ways, but the non threaded output shaft you can only use for slip yoke.

Do make sure you have the correct length driveshaft. If you're using a driveshaft that currently bolts on it would probably need shortened, but I'd imagine you're actually useing a 2 piece right now with the slip in the middle so you're needing to have one made anyone huh?

 

[mbl530]

@HotRodPC You have someone wanting to talk to you.

Thank you Scotty B.

 

[HotRodPC]

I see you're in a long bed truck. So my question is, why can't you use a 2pc driveshaft on a lowered truck? Probably a real simple reason and I'm letting it slip my mind. I know it's a 2pc driveshaft if it's got a bolt on yoke.

 

[mbl530]

on my flip kit, it is designed to move the rear,.end back an inch or so. This should let me use the stock drive shaft without it having any problems. I will need to move the carrier bearing up about an inch. This is what DJM calls for. Anyone who wants to discuss this, please do so. Already my pinion angle is around 4.5 degrees up, which may be too much, requiring a 2 degree shim, First I need to install engine/trans, and get that degree before doing anything.

 

[Emgeem]

I used these guys when I needed a new driveshaft for my 85. I changed tranny's & needed 3" longer shaft. The local shop wouldn't make one over 68" and mine was already 71". These guys built me a 4" Aluminum shaft with all new u-joints, new yoke...everything for around $500. It is really nice!!!

http://www.driveshaftspecialist.com/