SADS in early Previas

[TSWisla]

I have been reading through a lot of threads and there seems to be some confusion or perhaps misinformation on the SADS couplings for early Previas. I have a 1992 and was wondering what needs to be done when these fail? There was a discussion that the couplings can be replaced, but another person was adamant that they weren't replaceable, but that a later model shaft needs to be found from a junk yard, is this true? Is there still an OEM Toyota coupling kit available? Is it only used on the later shafts? If anyone can please clarify this for me, I would greatly appreciate it. Thank you.

[13ozLatte]

I have a 91. I changed my SADS, using the BMW coupler upgrade. Lots of posts on how to do that here.

The later ones use a different shaft, it's collapsible and easier to remove. But I was able to keep my original shaft.

[samstrader]

I have a 91 and replaced the couplers with the aftermarket aluminum ones twice. They lasted about 100K each. Then I put the BMW modification in using my original shaft. The BMW upgrade is amazing I think. It's way better and has worked great for 3 1/2 years. It's not that hard to do and I think it will be the last couplers I ever have to install. here's a copy of my post after install.

Re: Where is the best place to buy the best quality SAD coupling kit ??

I replaced the SADS couplers on my 1991 Previa (396000 miles) yesterday and used the Fibi BMW couplers from Pelican parts, part number 26-11-1-225-624. The cost for these couplers was $95.00 delivered. They were made in Germany and are very high quality. The fit up was excellent when the 3/8 inch brake line sleeves were used. I used a tubing cutter to cut the brake line to make the sleeves and was able to get them all exactly the same length, I did have to use a round file to file out the inner lip the tubing cutter made on each end of each sleeve.

It took me 7 hours to complete the job; I'm not sure how it took so long but I've always been a little bit slow.

The BMW couplers should last forever; I don't see how they could ever wear out. They are not nearly as flexible as the Toyota original design so I don't know if this will be a problem or not. With the Toyota design, the couplers provide a shock dampening whenever the air conditioner compressor kicks on and off but with the BMW couplers, it is more of a direct connect. However, the SADS shafts turns true and has no vibration. And mentally, I'm not worried about wearing out the couplers anymore.

Just like mentioned before, the BMW couplers make the SADS assembly about 1/4 inch longer (.201 inches actually) and this is only because the metal sleeves in the BMW coupler don't fit into the counter sink holes on the ends of the SADS shaft. I was worried about not using those holes with the BMW coupler because they provide some strength by taking some of the shear force off of the bolts, but I don't think this will be a problem. I tightened all the bolts to 30 foot-pounds of torque and there is no slack in the fit up of the coupler anywhere. I can't see how the bolts would shear.

I did adjust the three carriage mounts (all flexible floating mounts by the way) forward by a 1/4 inch. I had to remove a little metal (1/8 inch) from the center hole on the front two mount braces so the mounts could move forward a little more. My carriage was originally mounted almost fully forward apparently. I used a Dremel. The mounts are quite substantial so this metal removal didn't weaken anything in my opinion.

Before I removed any of the mounting brackets, I cleaned up all the parts where the bolts and nuts were attached and used a yellow paint market to draw around each bolt so I could put the mountings back together like they were. This worked out real nice. It was a lot of work up front but made putting the brackets back in place a lot easier.

Thanks to everyone for helping me decide how to replace my SADS couplers. I think I got a lot better job than I would have otherwise. I hope I never have to replace these couplers again because it is just not a fun job.

My hat is off to the original designer of this upgrade and I can't imagine how long it must have taken to figure out all of the details. it is a very clever way to install stronger couplers. This took some very clear understanding of how the whole SADS shaft is designed. Just a very clever modification all together and an excellent job. I can't say thank you enough to him for sharing his idea.

[samstrader]

Here are the instructions on how to make the BMW couplings.



First, there is this link to Zen Previa, in which he quotes a post from the Yahoo Previa group about adapting to a 91:

"...I used the BMW flexdisc part to replace the revolvers. All I needed was a piece of 3/8 steel brakeline ($3.00) to make some bushing-spacers for all 12 of the bolts. The brakeline material fit snug in the disc bushings and the inside diam. was just right for the original Toyota bolts. I cut twelve about an inch long and used them as I reassembled the new parts. The six bolt hole diam. in the BMW part matched right up with the Toyota revolvers perfectly. The BMW flexdiscs were a little thicker than the original (1/16 to 1/8 inch) so after I had the shaft back in I just adjusted the three accessory carriage mounts forward about 1/4 inch. It went together pretty well. No more SADS rattle and no more vibration, it runs out smooth.:-) And this is the best part for me, it cost me about $80.00 in parts and five hours of my time on Friday afternoon, not $1200.00. I got the new BMW flex discs (for 1987 BMW 325i, with automatic, driveshaft flex discs) from importparts.com, $37.00 each and free shipping, they came the next day. I don't know how they will hold up over the long run, but I have no reason to believe they won't hold up for many many miles. (the BMW part seems like a much heavier duty part) And I see no vibration increase on the accessory carriage. The whole van idles much smoother."

Yahoo Previa Group 5128 on Mon Apr 22, 2002 by beeman35051 - 91 dx 2wd with 137,000 miles



[I suspect that date is wrong, but it's no longer possible to search the group archive.]

Then there is a comment from another forum thread, in 2015, that this basic procedure also works for 95 shaft couplings if the bushing sleeves are cut lengthwise to expand slightly for the larger bolt:

"... They are incredibly tough. Consider they are used as the actual driveline couplers to put the rubber to the road on the 3 cars! They are a tad thicker, not a problem…maybe 1/8”. The holes line up perfectly. The holes are the wrong diameter (10mm vs 8mm bolts) so ... We chose the 3/8” brake line ... and cut them into 1” pieces, total 12... [then] cut them lengthwise with a Dremel so the bolts would fit through and it was not a problem and shims the holes just fine."


BTW, Tim (who runs this TVT list) also posted in that thread that he had used the Lemforder (BMW after-market) couplers successfully [but that was six years ago; Tim no longer has his Previa]. So that was three posts, using BMW dealer parts as well as Mehle and Lemforder after-market parts, all with good results.

[TSWisla]

This is excellent information. I appreciate you clearing this up for me. Thank you.