3.42 posi in a 72 skylark turbo swap

[turboskylark]

I am in process of 3.8 turbo swap in a 72 skylark,I also have a posi rear for a gn,I know the rear will not swap into skylark but what about posi carrier and 3.42 gears in a skylark 10 bolt with 2.56 gears? I am confused about series 2 and 3 rear ends.Also do you think this is the best route 2 go?I know I wont have any traction with the peg leg! Any help would be great on what direction to go.Thanks for the help! Pat

 

[mikestertwo]

I am in process of 3.8 turbo swap in a 72 skylark,I also have a posi rear for a gn,I know the rear will not swap into skylark but what about posi carrier and 3.42 gears in a skylark 10 bolt with 2.56 gears? I am confused about series 2 and 3 rear ends.Also do you think this is the best route 2 go?I know I wont have any traction with the peg leg! Any help would be great on what direction to go.Thanks for the help! Pat

The series refers to the offset for the ring gear on the carrier. A rear with 2.56 gears would be a series 2. A rear with 3.42 gears would be a series 3. A series 2 will have the mounting flange for the ring gear further away from the pinion than a series 3. This is because the smaller ratios use a larger diameter pinion gear. I don't think anything from the Skylark rear will interchange with the GN rear. I think the Skylark is a 8.2" where the GN is a 8.5". I'm sure someone else will chime in. My memory is a little fuzzy on this. Haven't dealt with the older rears since I got out of my Olds 442 phase. :biggrin:

 

[LBNJWE4]

wish I was closer, I have a 3 series posi rear out of a 71 Cutlass and I need a posi unit for a 8.5 GN rear!

 

[Ken Adams]

72 Skylark

The 71 and 72 Skylark came from the factory with 8.5" rear. 70 Skylark last year for the 8.2".

 

[turbofish38]

Funny. I have a 72 Skylark rear axle under my 86 GN. Yes you can use the GN posi and 3.42 gear in the Skylark housing. They are both 8.50" and 28 spline axles. The thing I like about the 71-72 B-O 8.5" axle is that they aren't C-clip. The axles are held in with bearing retainers. No need for a C-clip eliminator in other words.

 

[turboskylark]

Thanks for the quick replies, I still dont know if this will work,some say yes some say no?turbofish did you do the swap yourself and how hard was it?Do you guys think this is the correct gearing for the skylark with stock gn motor any tranny.thanks for any and all input. Pat

 

[Ken Adams]

72 Skylark

Turboskylark, if you would let me know the progress of your project. I also have a 72 Skylark GS 350, which I had planned on doing a BBB installation, but now may consider a turbo 6 instead. Depends on your input. Thanks

 

[LBNJWE4]

Funny. I have a 72 Skylark rear axle under my 86 GN. Yes you can use the GN posi and 3.42 gear in the Skylark housing. They are both 8.50" and 28 spline axles. The thing I like about the 71-72 B-O 8.5" axle is that they aren't C-clip. The axles are held in with bearing retainers. No need for a C-clip eliminator in other words.

Did it bolt right in? My Olds rear is under my '79 Regal and it is not on center. That is why I picked up the 8.5 to swap it out.

 

[turbofish38]

There is some welding required to swap in the 64-72 A-Body axle under a G-Body. I bought a kit from HP Motorsports which included 2 boxed upper control arms and 2 boxed lower control arms along with the new spring perches and shock mounts. The spring perches have to be cut off the donor axle and new ones are relocated and welded on and longer shock mounting studs need to be welded into the holes for the lower shock mounts. The 72 Skylark axle is approximately 3 inches longer than the G-Body rear. I made up the difference by having some new rear wheels made with a super deep offset. I am running the stock chrome steel GN wheels that have been widened to 10" with a 6.125 BS. Everything sits up under the sheet metal and I've even cut down the springs to lower it and nothing rubs even though you are limited to a 275 size tire. Anything bigger has to much cross section and will rub. I used to run a 285/40-15 Pantera tire when they used to make them. Those were only 25" in diameter. With this style of axle you have plenty to choose from as far as brakes go because of the universal 4 bolt axle flange. I'm running 11" drums from a 77 ElCamino. The stock park brake cables bolt up and when the tune is spot on I can spool the turbo up past 15 pounds and hold it although with a stock D5 convertor any thing past 10-12 pounds is wasted. I did this conversion over 10 years ago and I figure with the cost of the wheels I have about $800 wrapped up in it.

 

[turboskylark]

So the way it sounds, I can swap a 3.42 gear and series 3 posi carrier in a 72 10 bolt,cool!

ken,I have had my 72 since 1981,I bought it as a roller,rust free for $300 first put a buick 350 in,drove it for years,then about 8 yrs ago I dropped in a 1970 455,ran good but am not crazy about the gas mileage and wanted something different,so I decided with turbo v6,tranny and engine harness also have gn radiator,had to drill for frame pads,stock crossmember worked with a 400 turbo mount,350 driveshaft works,have it all bolted in still have to run fuel lines with gn tank,new p/steering lines and caspers dash mating harness, I am excited to get it done,but i have been busier than a cat covering cat sh*t!!. I should have some pics up soon,my 72 skylark is bright white with turbo t wheels.I wanted to have a t-type turbo and my old buick,but damn that cost too much money!So in my eyes I got the best of both worlds!!!!Anybody know if the g body buckets will fit and also t-type steering wheel on a A-body.Thanks for any and all help.:biggrin:
Pat

 

[turbofish38]

Steering wheel will fit. Seats should fit as long as you use your old seat adjusters.

 

[turboskylark]

Thanks for the info turbofish.