After 6 years and 65k miles I had my first "real" issue with my SOT MP62 SC kit (mine was beta kit #1).

After getting on it a few times the other day I started getting a grinding sound when the car would transition in and out of boost. My first thought was that 65k and no oil changes on the blower finally caught up to me and the SC was coming out for a rebuild. On the car I removed the belt and it looked like the nose pulley / snout assembly was toast since the pulley would move around a bit.

After pulling the blower and removing the snout assembly I found that the snout assembly was fine and what had happened was that the nose pulley was loose on the input drive shaft, even though the nose pulley nut was tight to spec. After removing the nose pulley from the snout assembly I found that it was pretty chewed up inside. A quick measure of the bore diameter showed that it was almost 0.25mm larger than the shaft diameter. I also noted that the key-way of the pulley was notched out on both sides where the key on the shaft was digging into it (see images below):





Fortunately the nose pulley is Aluminum and the input drive shaft is steel. I got the specs for the drive shaft and found it was still within the manufacturers designed spec (was not worn). The other fortunate thing is that the pulley is made by Track Dog Racing and readily available for about $100.

The apparent failure mechanism, in talking to the guys at Trackdog Racing is that the custom snout assembly for the SOT blower was likely just a bit out of specification and did not allow the clamping nut to fully fix the pulley to the shaft. They are going to send me a couple of shim washers to place between the clamping nut and the pulley that will prevent it from happening again.

Since the blower was already torn apart and I had the bearings, I went ahead and rebuilt the snout assembly and replaced the gear end bearings and coupler. I just regreased the needle bearings on the other end. Also went with a slightly smaller nose pulley that should give me a little more boost once it gets here.

 

I always loved these blower setups, glad you were able to find a solution and get some more ponies out of it

 

Hmmmm thanks for the heads up for the community. Don't hear about these kits to often!

 

Hey WLaurent,

Sorry to hear about the failure. I am still running my kit and just swapped out to a TVS 900 blower to keep intake temps down. There is a thread about it somewhere but I did not get a chance to get my new crank pulley in time before winter. So I ran it with too small a pulley which made it down on power but much smoother and quieter than the MP62. I think the new pulley will make it hit close to 350 at the wheels with a tune and max blower speed on an AP1.

If you have not sent your in for a rebuild, I have my original MP62 with about 7,000 miles on it. Was looking for a good home. I have no idea what it is worth but if you need it shoot me an offer. Right now it is a garage paper weight.

 

Mark sold his car to a local guy. We are all friends but his is still doing good.

I'm in the process of installing one of the kits on my car now.

Vader, I got the pulley back, let me know if you ever need it again

 

I think I am good, fingers crossed. But if the shop screws it up and my second car finally arrived and the S is down for winter I am pulling my own. If the first shop can't get it done soon I will try another one, but they say they are waiting to send it out for hardcoating when they have other parts to be hardcoated to save me some money on the pulley.

But thanks again.

John

 

that is a lot of mileage. very nice. i sold mine but cant wait to see what vader puts down next year. winter, whats that......LOL.

 

Hey guys - Hows everyone doing?

I actually rebuilt it myself. All it took was about $150 in parts, watching a couple how-to videos on youtube, and I had to borrow an arbor/shop press for the day. It is back in the car and running.

My last dyno when I switched to the KPRO with a 140mm crank pulley had me at 345 RWHP with a very safe all season tune. That was 3 years ago, going to bring it back in for a winter tune to see what we can squeeze out of it and then just dump my current tune back in when it starts heating up here in the desert.

John - I was considering doing a TVS900 or TSV1050(if they ever release it) and I did follow your thread on it. I may take you up on your MP62 - will PM you my cell number and you can call me at your convenience. May be nice to have a spare sitting around.

 

I am still running my beta SOT kit. Has about 50k miles. No serious problems yet. I need to go ahead and do the oil change.

 

I'm running mine, 320 whp e85, 290 on pump gas. Problem is I still have the heat sticking throttle issue. Can't find the right TPS sub-part replacement. Love the kit.