V8 swap question

[Swed_SS]

ok, so i have this 1991 744 TI with a blown motor and i'm crazy to do a v8 swap in it. i just bought a running LT1 with transmission, ecu and wiring out of a 95 buick roadmaster for $600. i know there are a ton of "complex" things to worry about especially with an LT1 but i'm prepared for most of it. i only have 1 question. what length of a driveshaft will i need for the swap? i know the 200 series requires a 47.25 inch and a 2.75 inch diameter but idk if the 700s require the same, someone please help me figure this out so i can get this thing going!

[Mueller]

Originally Posted by Swed_SS

ok, so i have this 1991 744 TI with a blown motor and i'm crazy to do a v8 swap in it. i just bought a running LT1 with transmission, ecu and wiring out of a 95 buick roadmaster for $600. i know there are a ton of "complex" things to worry about especially with an LT1 but i'm prepared for most of it. i only have 1 question. what length of a driveshaft will i need for the swap? i know the 200 series requires a 47.25 inch and a 2.75 inch diameter but idk if the 700s require the same, someone please help me figure this out so i can get this thing going!

measure distance right now while stock motor is in car, write down, adjust accordingly???

each install might be a little different depending on how you mount the engine

[swiftjustice44]

Each install will be different. When I did mine I wanted all the answers up front too. It kept me from doing anything for almost a month. Even so, working on it when I could, it took me all winter. Just start at the front and work your way back. The drive shaft alterations were actually one of the simplest things to do. Stab motor and transmission, measure distance...chop away.

[M.H. Yount]

As others have said - get YOUR engine mounted in YOUR car with YOUR mounts. Then measure and have one built. No one can tell you with certainty what length you'll need.

[photoman327]

go for it. The LT-1 in the roadmaster is rated at 260 HP stock and with the front mounted distributor no firewall issues.

[Swed_SS]

i know, i feel lucky that i got a good running one for so cheap. a guy i work with bought the car for 600 bucks to part it out and he said he'd sell me the motor with all the accesories on it all the way back to the driveshaft yolk. when he finally pulled it the only wire he snipped was for the abs. and as far as the driveshaft stuff goes, i guess i'll have to wait, but i was planning on getting one custom made from scratch to handle up to 500hp cuz they're not too expensive. try around 300 dollars for a brand new fully balanced steel one that takes the spicer 1310 u-joints that JTR says to use.

[M.H. Yount]

Driveshafts are sized for a torque rating, not HP. FWIW for the torque that's going to come along with that HP level - I'd opt for 1330 Spicer joints. And a 3" aluminum should fit, handle that power level and run with noticeably less NVH than a steel unit, not to mention the reduction in parasitic losses from the (much) heavier steel unit. Sizing is almost always done to manage critical speed issues -- not the torque requirement. A shop close to me has quoted me a 3" aluminum unit for very little more than you're quoting for the steel unit....

[Swed_SS]

so you're saying that a 3 inch would fit? would i have to make any adjustmends to make it fit? and i would rather go with aluminum BECAUSE its much lighter, and all the online stores seem to be able to make the aluminum ones for around 400 and some dollars which seems like a pretty good price.

[photoman327]

My iroc has one and I never measured the length. Seem like you could get a used one and visit a driveshaft shop and save a ton.

[M.H. Yount]

Getting a used one may not be all it's cracked up to be. If it's not straight (often they're damaged at the boneyard as even dropping them can bend them enough to cause vibrations) it has to be straightened. And straightening them is never as good as having one that's never been bent. They still have to cut off at least one end, weld, check for straightness after the weld, balance. You can save on the tubing stock and perhaps the yokes. So - if you can find something that has the exact ends on it that you want, and it just needs to be shortened -- you can save a few bucks. Otherwise - you're not going to save a lot.

Swed - SS - Mine is a 240 - lowered a bit. A 3" is the maximum that will work in mine. But every car is a bit different. When I had the 8.8" rearend fabricated for it - we moved the center section towards the driver's side a bit to better center the shaft in the tunnel. The tight spot for me was on the passenger's side around the back seat. Every car is going to be a bit different depending on suspension choices and where the motor/tranny were positioned on the swap. My sense is that the 740 has more room underneath for the shaft -- but that's a guess on my part.

[Swed_SS]

yeah i wasn't planning on buying a used one or even buying a new oem one that needs to be hacked, too expensive. i already knew that it would be a much better and safer idea to just get one custom made. price wise, its cheaper to buy a custom made steel one than an oem chevy one brand new anyway, plus the oem chevy one would need resized. also, all custom made shafts are precision balanced, and i'm not gonna say no to that.

http://www.pstds.com/custom_driveshafts.htm#

the link above is from Precision Shaft Technologies and their starting prices are wicked low so i think i'm gonna jump on one of those. 300 dollars for an aluminum shaft with the yolk i'll need or 350 dollars for a chromoly. in any other case i wouldn't be spending this much on a driveshaft but it DOES need to be precise and since i ended up paying so little for the power plant, i have room in the budget for one.

[M.H. Yount]

You can play around with this to get an idea of the dimensions/speeds/torques involved.... http://www.wallaceracing.com/driveshaftspeed.htm

[Surelokhommz]

Originally Posted by Swed_SS

ok, so i have this 1991 744 TI with a blown motor and i'm crazy to do a v8 swap in it. i just bought a running LT1 with transmission, ecu and wiring out of a 95 buick roadmaster for $600. i know there are a ton of "complex" things to worry about especially with an LT1 but i'm prepared for most of it. i only have 1 question. what length of a driveshaft will i need for the swap? i know the 200 series requires a 47.25 inch and a 2.75 inch diameter but idk if the 700s require the same, someone please help me figure this out so i can get this thing going!

Man im in the same spot you're in. I got a 86' 240gl and im swapping in a 98' Ford 3.8 with 37R turbo. Im guessing from what their saying on here and what ive read on other sites on swaps is...
Drop in the engine, fab up mounts, figure out what rear-end to use and mount it up then get all the measurements for driveshaft from yoke to yoke.

Im going to "Try" and use the volvo rear-end for simplicity and have a shop build a shaft using Ford front drive line yoke, custom line and mate it up to the volvo yoke.

Someone please correct me if this sounds implausible.

[Mueller]

Originally Posted by Surelokhommz

Man im in the same spot you're in. I got a 86' 240gl and im swapping in a 98' Ford 3.8 with 37R turbo. Im guessing from what their saying on here and what ive read on other sites on swaps is...
Drop in the engine, fab up mounts, figure out what rear-end to use and mount it up then get all the measurements for driveshaft from yoke to yoke.

Im going to "Try" and use the volvo rear-end for simplicity and have a shop build a shaft using Ford front drive line yoke, custom line and mate it up to the volvo yoke.

Someone please correct me if this sounds implausible.

sounds fine to me....$20 for a 5.0 shaft , $110 for professional balancing (price I was quoted and that included shortening it if needed)

[TestPoint]

As Michael said above a 3" torque tube is about as big as will fit in the tunnel. I used a FOX body 3.8L shaft which is 2.75". Shortened it and used a Spicer 2-3-329 flange yoke to match the Volvo pinion flange. Look for shafts using the 1310 u-joint as you are going to have a clearance problem with a 1330 joint/yoke at the spline yoke end.

I paid $20 for the shaft, $45 for shortening and rewelding, $25 for balancing, $32 for the flange yoke. Plus $20 for two new u-joints.

[Swed_SS]

Originally Posted by Surelokhommz

Man im in the same spot you're in. I got a 86' 240gl and im swapping in a 98' Ford 3.8 with 37R turbo. Im guessing from what their saying on here and what ive read on other sites on swaps is...
Drop in the engine, fab up mounts, figure out what rear-end to use and mount it up then get all the measurements for driveshaft from yoke to yoke.

Im going to "Try" and use the volvo rear-end for simplicity and have a shop build a shaft using Ford front drive line yoke, custom line and mate it up to the volvo yoke.

Someone please correct me if this sounds implausible.

the volvo rear should take up to 450HP or so i've read. but that is from people who run non turbo V8's. honestly if you have anymore than 350hp ESPECIALLY with a turbo motor you want either a GM 8.5 of a ford 8.8 rear. Turbo motors are more critical because of how they make torque.

[kildea]

Originally Posted by Swed_SS

the volvo rear should take up to 450HP or so i've read. but that is from people who run non turbo V8's. honestly if you have anymore than 350hp ESPECIALLY with a turbo motor you want either a GM 8.5 of a ford 8.8 rear. Turbo motors are more critical because of how they make torque.

what rear did kenny have on his car when he broke into the 10's?

[Surelokhommz]

Originally Posted by TestPoint

Look for shafts using the 1310 u-joint as you are going to have a clearance problem with a 1330 joint/yoke at the spline yoke end.

Sorry for my ignorance but what is a 1310 and 1330 joint?

As to if that applies to clearance within the tunnel, ive just recently cut out my stock tunnel in case i needed to fit a massive driveshaft. That and most the floorboard was rusted to Hell.


Swed_SS, what rear do you think your going to use? Ever think about just upgrading the Diff to Dana 30 or Quaife? Ive done quaife's in many Fwd cars ive built in the past ive been more than happy with them.

[89sleepr240]

When I had the engine and transmission in the car, the rear end finished and in the car, and everything else in place, I measured the length I needed. I then went to a local driveshaft shop (American Driveline in Dayton, OH) and told them what I was doing, what my goals were, the weight of the car, and that I would be launching on slicks. They made a driveshaft for me based on that information for about a hundred bucks, but I think I may have gotten a bit of a buddy price.

[Mueller]

Originally Posted by Surelokhommz

Sorry for my ignorance but what is a 1310 and 1330 joint?

As to if that applies to clearance within the tunnel, ive just recently cut out my stock tunnel in case i needed to fit a massive driveshaft. That and most the floorboard was rusted to Hell.


Swed_SS, what rear do you think your going to use? Ever think about just upgrading the Diff to Dana 30 or Quaife? Ive done quaife's in many Fwd cars ive built in the past ive been more than happy with them.

More/better options if you go with the Ford or Toyota rear axle, no direct bolt-on Dana 30 option , and a Quaife diff still does not address the next weak link in the stock rear end, the axles....

[TestPoint]

U-joints come in pretty standard sizes, 1210, 1310, 1330, 1350. Most passenger cars use the 1310 size that has a yoke rotating diameter of about 3.5". The 1330, used by light trucks, such as the Ford Explorer have a rotating diameter of about 4.8". The Volvo used the much smaller 1210 with a rotating diameter of 2.7"

Here is a link to a Dana Spicer slip yoke catalog with all the dimensions (see page 17/18 for the 28 spline Ford AOD/4R70W slip yoke): http://www2.dana.com/pdf/J300-P3.pdf

Here is a link to the Dana Spicer drive line design book. More information than you ever wanted to know: http://www2.dana.com/pdf/DSAG-0200.pdf

[Surelokhommz]

Wow! Great info guys. I now feel a bit more educated. I also see what you mean by "more info than you ever wanted to know"!
The math is quite a bit out of my league.

So now I know that the volvo rear end WILL NOT hold up to the power I will be making, which I thought was gonna be the answer, before I can have the driveline made I have to choose a new rear-end.

What are my options ?

So by switching to a new rear-end I will essentially have to swap everything rear-end wise, aka rear axles, diff, brakes, suspension mounting locations?

[Captain Bondo]

Kenny has an automatic and he's careful to load everything up and take the slack out before he gets on it on the strip. It's also either a weldie or a G80.

If you don't mind those options and have an automatic, you can do ok with a dana 30.

If you want a non-pos LSD, and/or have a manual trans, and or want to turn corners, a diff swap is relatively straight forward and relatively cheap in the context of an engine swap. So much so it's hard to justify NOT doing it imo. Fix it once and forget it.

[Surelokhommz]

ideally I'd like to keep the Volvo rear just to simplify things and just build the piss out of it...if possible. If thats not an option so be it.

[Mueller]

Originally Posted by Surelokhommz

ideally I'd like to keep the Volvo rear just to simplify things and just build the piss out of it...if possible. If thats not an option so be it.

figure $500 for the LSD, another $400-$500 for custom axles and another $400 for stronger (if available) ring and pinion (which will be the weakest link after the other 2 items)

it is an option, just not one I'd pick and I'll be lucky if I make more than 225 hp !!