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yegoshin

Driveshaft lengthening question 5speed D/R swap

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Hey guys, just getting to the driveshaft part of my EJ into BRAT swap. I am putting a 5 speed D/R into it and want to keep a 1 piece driveshaft. Who has done this by getting thiers lengthened?

I went to a shop today and the guy said that in order to do it he will have to go to larger diameter pipe at least in the middle and he wanted to charge me like $210 to get it done, with the donor pipe being far from brand new. Anyone got any suggetions? (no I dont want to get a 2 piece and weld the carrier bearing in place)

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Hi This is Jerry, if you keep the 5 speed in the stock location in your brat then you will need 51 inches of new tubing. In Yakima Washington the shop is call Drive line service they charge me on my last drive line 112.00 to lengthen it and balance it same size of tubing that the stock drive line used. Thanks Jerry

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Jerry is right on the money, I kept the one piece driveline when I went to the 5spd d/r in my ej brat, mine was ~$135 in Eugene OR, driveline specialties I believe. I switched to servicable (greaseable) toyota u-joints at the same time, then the driveline is easily rebuildable, I've seen/heard of this in many applications, and any custom driveline shop worth their salt will stock toyota/nissan u-joints(subaru u-joints are nary impossible to find). I'm going this route with the 3.70 awd d/r going into my legacy this week or next. The only reason I see for a two piece in a subaru is it's easy to remove the rear section and still drive in fwd. I would keep a uniform size pipe for the whole length of the driveline.

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Thank you guys for your replies, if anyone one else wants to chip in with thier experience as well feel free.

 

Did ether of you get the driveline shop metioning something called critical speed? Apperantly when the shaft is too long and too thin at certain RPM's the shaft will reach natural occilation and will bend itself ? The guy I went so said that the stock shaft diameter is too thin to be that length and would naturally occilate 'till it bends itself.

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Hi This is Jerry, the place that i had my drive line lenghten is drive line service thats all they do. The first drive line i brought to them the guy look at it and said ok not a problem. I have over 100,000 miles 3 drive lines that shop has done for me. I haven't bent 1 yet. This place makes the drive lines for these 25 foot tall wind machines that is around here. Thanks Jerry

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He's making it sound like a big deal so he can charge you more, and scare you off from doing it yourself. Subaru over-engineered nearly everything, and an extra couple inches in the driveline isn't going to make a difference at all. Besides that how does he know how thick it is? He cut it open to find out?

 

Frankly - my money is on doing it myself, and then just having a driveline shop balance it for me. Just cut the tube in the middle, and get some tube that is slightly larger to slide over the existing tube. Drill a lot of small holes in the sleeve, and fill them with weld. Then just have it balanced.

 

Another thing - stock soob u-joints are serviceable - at least all the ones I've seen on EA81's are. Replaced a couple myself actually.

 

GD

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For driveshafts in general, the man in question is right, and obviously unwilling to take any risks, what he values his work at is a seperate issue. The reason for going to 2 piece driveshafts in the first place is to prevent bad things happening. The longer a driveshaft is the larger the diameter required to keep it rigid. The larger the diameter the heavier it is, and the more inertia you have, and the harder it is to balance. Im not an engineer, but im sure subaru have some and there is a point where splitting the driveshaft into 2 or more pieces makes sense for reliability, weight and balance. Ive seen the results of driveshafts letting go and its one thing i would always take professional advice on. If youre lucky it wont destroy youre car :)

 

If Jerrys man says its ok then i'd take his word for it, but id be looking to someone with that kind of experience for advice becuase the driveshaft is something you dont want mishaps with. You DONT cut and weld in the middle, you do it at the end by the joint.

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thank you for the reply's I definatly dont want to do a bad job after investing A LOT of time into the suby as is, especially since if the driveshaft is to pull out the tranny fuild would follow quickly.

 

I am just trying to do as the research, get all oppinions possible before spending hard earned tax returns :D

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This is a SUBARU - it's not a swiss watch people. This is not rocket science, and people will not die if some of the foam comes off a wing. Get real.

 

Jeezuz

 

That said, it's a heck of a lot simpler and cheaper to just use the 2-peice. It's proven reliable. Personally, I've seen axles, and driveshafts cut and welded in the middle. You just have to know what you are doing, and how to properly weld it with the sleeve covering enough of the existing shaft, and the holes in the sleeve beveled and welded properly. There is not just ONE way to do things, and people haven't always had access to sophisticated equipement for this type of thing.

 

GD

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This is a SUBARU - it's not a swiss watch people. This is not rocket science, and people will not die if some of the foam comes off a wing. Get real.

 

Jeezuz

 

That said, it's a heck of a lot simpler and cheaper to just use the 2-peice. It's proven reliable. Personally, I've seen axles, and driveshafts cut and welded in the middle. You just have to know what you are doing, and how to properly weld it with the sleeve covering enough of the existing shaft, and the holes in the sleeve beveled and welded properly. There is not just ONE way to do things, and people haven't always had access to sophisticated equipement for this type of thing.

 

GD

 

 

Maybe not rocket science, but ive seen what happend when driveshafts let go, and walking funny for the rest of youre life because a driveshaft came thru the floor doest look very pleasant! A d/shaft that lets go at the gearbox end is perfectly capable of vaulting the vehicle onto its roof. At the very least it will do serious damage to youre vehicle that you will regret. If the driveshaft is short enough it will tear the car apart, ive seen a hotrod that the shaft destroyed the gearbox, diff and battery/fueltank/seat/structure in between. The driver (a past employer) was stunned to get out without a scratch.

Thats why I recommend caution to someone whos never done this before, im not trying to have a dig at you personally mate. I weld my own axles and driveshafts too with no problems so far, but thats my problem if it fails.

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