need some help from you professor Tim

[Previa dude]

Ok here is the the short of it. Sam is my 91 previa le. I finally replaced my equipment shaft couplings because she started having a vibration (groaning sound) when accelerating from a dead stop. So I ordered some off ebay. While taking it apart I notice the equipment shaft housing mounts were craked, and had some dry rot. So I ordered all three from toyota. I got it all put together just now. New couplings and mounts. Now she vibrates worse. I have a Chilton repair manual on the alignment of the housing but it is kinda vage and didn't really cover 90-93. So I did the best I could with what I had. Do you have any advice professor T ?

[timsrv]

This can be a problem area as balance & alignment are critical and require strict adherence to Toyota's installation instructions (please view attached PDF at the bottom of this post). Even if you do everything right, the other issue is unknown quality of aftermarket parts. In a nutshell, your options are limited for 91 - 93 because Toyota doesn't make/sell flexible couplers for these older shafts. If you use the original shaft, your only choice is to use questionable quality aftermarket parts. After messing with this a little bit myself, I don't recommend trying to repair the 91 - 93 shaft. If you do, at the very least, you should have the assembly balanced before reinstallation (but finding somebody to do that may prove difficult). Even if you get everything balanced and aligned, then it becomes a question of how long the aftermarket parts will last. Because of that, I can only make 2 recommendations:

1. Find a SADS shaft in a salvage yard from a 94 - 97 Previa, then buy the OEM Toyota couplers and install them.....FOLLOW TOYOTA'S INSTRUCTIONS TO THE LETTER!!!

2. Buy the entirely new shaft assembly from Toyota for a 94 - 97, then install that.

#1 would likely be more problematic because who knows what the salvage shaft has been through (will the complete assembled shaft be balanced???). My guess is "probably", but nothing like spinning the entire assembly for verification (I'd still want to find somebody to balance it). I know there are guys out there capable of doing this, but it might be hard to find a local drive-line shop with a tech willing or even capable of deviating from to norm to do something "unusual" (It would likely require some special "tooling-up" to mount the shaft correctly on a balancing machine).

#2 would be the best way (new shaft would be pre-assembled & balanced from Toyota). But unfortunately this part will cost you around $1,500 .

If you can't spend any more money and you need to make it work, then there are things you can try (that may or may not work). At the very least I would read the provided instructions (PDF at the bottom of this post) then go back and check your work. If everything was done correctly, then you might try balancing the shaft yourself using hose clamps. This is a "dirty" way of balancing, but it does work. Get yourself some stainless hose clamps big enough to fit around the shaft (get the ones with the adjuster screw). Safely secure the vehicle and get under the van with a piece of chalk. Safety is a big issue here, so proceed at your own risk!!!. Start the van and have somebody hold the rpm's around 3k, then carefully touch the shaft with your chalk (I'd do it on front & back near the couplers). Shut off the van and check the chalk marks. If the shaft is out of balance you will see a heavy chalk mark on one side but light to no chalk on the other. Now put a hose clamp on the shaft & position the screw part to be opposite (180 deg) from the heaviest part of the chalk mark. If there's much excess on the clamp(s), cut it off. Now repeat the part where you marked with chalk and compare results with what you got before. You should see the chalk line becoming more uniform. You will need to be extra careful once you have hose clamps on the shaft as these can be wicked dangerous while spinning around............especially if you have big excess of unused clamp whipping around. I recommend positioning the clamp so the excess (if any) spins in the direction as to prevent it from snagging if it contacts anything. Repeat this procedure as required until the chalk line is consistent (uniform).

The reason this works is due to centrifugal force. When one side of the shaft is heavier than the other, centrifugal force will push that side outward. This means the chalk will touch that side 1st. Since the screw part of the hose clamp is the heaviest, it will help to off-set the unbalanced condition. If you don't want to use hose clamps, and if you have a welder, you can achieve the same thing by welding washers to the light side, but it's best to dial it in with hose clamps 1st (so you know it's a balance issue & not an out-of-round or bent shaft issue). Tim

PS: In addition to the balance, it's also important to achieve alignment (the separated accessory assembly needs to be in a straight line with the engine). Any time the mounts are messed with there is potential for misalignment to occur. I would highly recommend you purchase a factory service manual and refer to the cooling system part of the manual (as that outlines the alignment procedure). Tim



PREVIA SADS TSB.pdf

[timsrv]

Here's a rare find: http://www.ebay.com/itm/TOYOTA-PREVI...a8cb31&vxp=mtr

[Previa dude]

I was wondering if I had to to rebalence the shaft. Sound like I wasted 100 dollars a 2days. Oh well.... off to the dealer she gose. I guess I'll just have a new shaft installed and have them align the housing. I guess on a the plus side I was able to clean and repaint the housing which looks really nice. Sigh (input common curse words here).lol

[timsrv]

I would at least snag that eBay shaft. The seller claims it's a new OEM Toyota shaft. Assuming he's telling the truth, that will save you ~$1k in parts. Of course some stealerships are butt heads when it comes to installing parts purchased elsewhere. You might call them to see if they'll install parts provided by you. Better yet, get the manual and install it yourself. The alignment process isn't all that terrible. If you're able to follow directions, you should be okay. They call out a special tool (SST), but with a little ingenuity I'm sure you could make something that does the same thing. Tim

[TheMAN]

wow.. that's a hot deal... definitely get it!
the new shafts are a 94 redesign and are much stronger... plus, you can eventually get the OEM toyota coupling kit when these go bad!

[apham8]

Here's a rare find: http://www.ebay.com/itm/TOYOTA-PREVI...a8cb31&vxp=mtr

This link is no longer active, but the link states the Part number being 37910-28050, which I am assuming is the equivalent of the 94-97 Previa's factory installed SADS shaft?

I recently purchased a 1997 Previa's SADS shaft from the salvage yard, anticipating that my current SADS shaft will need the couplers replaced eventually. I drive a 1992 Toyota Previa LE 2WD by the way. So I figured that I would have the 1997's SADS shaft ready to replace with the coupler kit from Toyota.

But I called the repair shop that the previous owner used for this Previa today. The SADS shaft was replaced in 2010 with part number: 37910-28050

wow.. that's a hot deal... definitely get it!
the new shafts are a 94 redesign and are much stronger... plus, you can eventually get the OEM toyota coupling kit when these go bad!

Along with this quote, I'm assuming that I do indeed already have the 94-97 updated Previa SADS shaft that is compatible with the Toyota OEM Coupling Kit available from the dealer, part number 04374-28011.

I see people reference this SADS shaft part number 37910-28050 as the updated SADS shaft, but I wanted to confirm that this is indeed the equivalent SADS shaft that I have from the 1997 Previa that I pulled it from.

I'd prefer to have had a new SADS shaft that was installed in 2010 that is compatible with the Toyota OEM coupling kit because I know there's a bearing on the front end that is not replaceable. The 1997 Previa had 315,000+ miles on it, therefore that bearing has had a lot mileage.

[timsrv]

That coupler kit from Toyota should work on both of your shafts.......it just won't work on the original 91 - 93 shafts. FYI, the 91 - 93 shafts went obsolete/unavailable early on so by 2000 or so you couldn't even get them anymore. The new "beefier" shafts are completely interchangeable as an assembly, you just can't use the new couplers on an old original shaft. Tim

[apham8]

Ok, thanks for the confirmation timsrv. The previous owner of this Previa took really good care of it. Replaced the SADS in 2010 and even replaced motor with low mileage JDM engine at 393,xxx miles when head gasket gave out. I guess I’m good to go for a little while then.