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Discussion Starter · #1 ·
Hey guys looking for opinions on whether to go with a SYE/CV or not. Here is my set up:
99 5.7L Vortec engine swap with np231 adapter which moved my TC 5" further from my rear axle. 2.5" lift on 31" tires. I obviously had the rear axle lengthened to work with this set up. Runs pretty smooth with stock Dana axle. I am ready to weld up the mounts on my ford 8.8 and put on my 33x12.5 tires. I have a chance to by a already converted NP231 TC with SYE installed and CV shaft for $300. I don't really have the desire to fork out the cash right now but I could pull it off. Considering the ford axle is offset by a few inches should I go ahead and get the SYE and weld my brackets for the correct angle required for a CV set up accordingly? Does anyone have a set up like this running standard u joints and not have driveline vibration? Like I said mine is pretty good right now but the extra height of the tires and the axle offset might be too much to hope for no driveline vibration.
Opinions?

Thanks!
 

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First off, tire height doesn't effect driveline angles. Think about it, they move everything up, frame and body. And if your t-case is moving forward 5", that lengthens the driveshaft which makes vibes less likely. Finally, a 2.5" lift alone doesn't require a sye/cv setup. If you're going to do a TT at some point, I'd go a head and get the sye/cv. But if you're not, then save your money.
 

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I don't have my 8.8 yet but I assume you are aware that there is a strong chance of vibration when you install it due to the pumpkin not being quite centered anymore? You may have negated that with your move forward though. Although an SYE is usually not a bad thing.
 

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I have a 97 with a conversion that moved the transfer case forward as well. It has a 5in lift and I had vibrations before I adjusted the angle of the motor/transfer case. The previous owner didn't have any slope which really made the angle of the joint at the transfer case too great. I was able to cut some of the height out of the transmission mount and lower the back of the engine which eliminated the vibration. I found a D44 out of a tj. The angle at the axle and TC are now as close as I can get them.

But I am still going to do a SYE and CV drive shaft as I would prefer that setup anyway. I intend to move the motor and transfer case back a few inches as the PO set the engine too far forward. Once I do that, I will be installing the SYE and CV.

That is a great price on that setup and I would recommend buying it in anyway, even as a backup to your current setup. With the power you are putting through the TC with the SBC, it wouldn't be a bad idea to keep a spare.

How long is the drive shaft? Will it bolt in to your application with your TC being moved forward?
 

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Discussion Starter · #5 ·
PC: yeah I wasn't thinking when I was typing on the tire diameter not mattering, just trying to give everyone enough info to form opinions.

Tanks and Dave: I know the price is right on the SYE/CV just since "FrankenWrangler" was just brought to life 3 weeks ago and I have everything for the 8.8 swap I didnt want to spend more money. The only reason I am doing the 8.8 now is because I have the 33's I want to put on and don't want to put the strain on my Dana gears. My previous TJ "Carlos" blew out the rear end with 33's on it and I don't want to do that again.
Dave: what engine did you use for the conversion? My 5.8L Vortec SBC could not possibly be pushed back anymore, if it was there would be no way to remove the distributor if I had to, its that's close to the firewall and where the hood hangs over.
I know about the pumpkin offset, will just have to see if the extended drive-line is enough to keep it reasonable. I would have to have the CV shaft altered if i bought it too.
 

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I bought the jeep already converted. It is an LT1. I learned later that it is probably not the best choice due to the optispark distributor being on the front of the motor and their tendency to fail when it gets wet. Granted I have learned a lot about what 'not' to do.

But, it has almost almost a foot between the firewall and the back part of the engine. It also sits very low in the engine bay. Although that seems to help with a lower center of gravity, it is limiting my uptravel of the front suspension. I am going to raise the engine around 4 inches and push it back around the same. As it is now, I can't use a regular air intake as the plenum sits too close to the radiator.
 

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Regardless of potential problems with vibrations, if you're planning on off-roading much I'd look at getting an SYE. I've seen the stock 231 output shafts bend pretty easily.
 

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Regardless of potential problems with vibrations, if you're planning on off-roading much I'd look at getting an SYE. I've seen the stock 231 output shafts bend pretty easily.
Or worse, you blow a ujoint in the rear and the shaft has to come out and you limp/winch yourself out in front wheel drive with a tshirt stuffed in your rear output to keep from spewing tcase fluid until you get to somewhere AAA will get to.
 

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Or worse, you blow a ujoint in the rear and the shaft has to come out and you limp/winch yourself out in front wheel drive with a tshirt stuffed in your rear output to keep from spewing tcase fluid until you get to somewhere AAA will get to.
The stock slip yoke on the TJ's 231 won't leak fluid with the rear shaft removed.
 

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Discussion Starter · #12 ·
Finally did the axle swap last weekend. Started at 6:00pm on a Friday night and finished mid afternoon Sunday. It only took me 90 minutes to completely pull the D35 off. Then a lot of test fitting, adjusting, welding, painting, etc. and I had the 8.8 in FrankenWrangler. Took it for a test drive after bleeding the brakes and was extremely happy that I had no drive line vibration! It was a chose as I did it all myself, thank goodness I have a tranny jack I used to move the axle around.
Thank you all for the advice you gave me!
Terry
 

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I have a 97 with a conversion that moved the transfer case forward as well. It has a 5in lift and I had vibrations before I adjusted the angle of the motor/transfer case. The previous owner didn't have any slope which really made the angle of the joint at the transfer case too great. I was able to cut some of the height out of the transmission mount and lower the back of the engine which eliminated the vibration. I found a D44 out of a tj. The angle at the axle and TC are now as close as I can get them.

But I am still going to do a SYE and CV drive shaft as I would prefer that setup anyway. I intend to move the motor and transfer case back a few inches as the PO set the engine too far forward. Once I do that, I will be installing the SYE and CV.

That is a great price on that setup and I would recommend buying it in anyway, even as a backup to your current setup. With the power you are putting through the TC with the SBC, it wouldn't be a bad idea to keep a spare.

How long is the drive shaft? Will it bolt in to your application with your TC being moved forward?

that is an extremely cheap price for an np231 with a fixed yoke and a cv shaft ... you would have over 300 in just the sye and cv shaft alone .... stock 231's without a rebuild often sell for around 300 here
 
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