One thing was sure. I wanted to trust the job with someone who was a transmission specialist. Not a general workshop.
BHPian BowMan recently shared this with other enthusiasts.
My 722.9 rebuild journey starts about two years back when I got myself an W211. The car ran beautifully for a year and then suddenly one day my dad was driving it and I thought I heard the first signs of transmission slippage. Initially I wanted to wish away my worst fears but after about 20-25 Km of driving back home all doubts were laid to rest and sure enough the transmission was slipping, and the car limped back home.
Once home I called my friendly mechanic and discussed the symptoms. Now as it was, the car was at 65K Kms, so the 722.9 tranny fluid change was due. We decided to do a fluid change and see if it helps the situation. Few things about this procedure. I had specifically instructed my FNG to call me up when he drops the pan as I personally wanted to inspect it. However, for some reason he failed to do this. He even did not manage to take any pictures of the transmission pan which could be inspected later. I was a little bit annoyed at this, but the fluid change did seem to cure the issue at least for some time.
However, the good news did not last long. Within a few weeks after returning from Ahmedabad I again had the same symptoms. The car had to be transported on flatbed to the mechanic. It was obvious that the fluid flush had not solved the issue, so we agreed to take out the tranny and do a service. This would include cleaning and checking the valve body, solenoid flush, and the likes. We would then drive the car for a few odd hundred KMs and open the pan to see if things were holding up or not. Now again the tranny service was done by my mechanic in a bit of hurry so I could not personally inspect my transmission when it was out of the car. However, my mechanic did confirm a lot of debris and some wear on the front planet carrier.
I was staring at a tranny rebuild now. However as planned I did drive the car for 700 Km after the flush and then we opened the pan. The sight was not good, and I found my magnets covered with debris. By this time, I had also invested in a Xentry system. I took readings of my clutch fill times and I could see that some of the important clutches were near the end of their adjustment spec range.
So, I started to gather information about possible transmission rebuild specialists. One thing was sure. I wanted to trust the job with someone who was a transmission specialist. Not a general workshop that can also do transmission rebuilds. The 722.9 trannies are relatively very simple to open and reassemble and no special tools are required. However, to do a rebuild that lasts is something that is complicated with a lot of specifications that need to be checked every step of the rebuild. Most workshops that claim to do transmission rebuilds do not have a complete idea of what they are undertaking. What they are doing is opening up the transmission, plonking in new parts, and hoping the things lasts at least till sometime.
However, it was getting difficult to locate a transmission specialist. In most of the workshops I inquired around the country the scene there was general workshops were also doing transmission jobs. I called a few such workshops and put a probing question to them. None of them gave me a satisfactory reply. I had also put up a few inquiries on WhatsApp groups. I got a response from one of the Groups with a lot of esteemed Mercedes enthusiasts in and around Mumbai area and one of the more promising lead was Sehmbi Transmission in Madh. The rest were again mostly general workshops, some of which were very reputed, but not transmission specialists. I was told by the person that though he had not used their services but knew they have been in business for a very long time. All this made Sehmbi look very promising to me as a partner to take care of my transmission rebuild project. After a few more days of exhausting other leads, I finally decided to call Harjeet and asked him a few probing questions. He came across to me as someone who is very technically very sound. As it happened a few other incidents reaffirmed my assessment that Sehmbi was the best option. I was suspecting that given the number of debris on my magnets not just the bell housing end but the Torque Converter also needs to be replaced or rebuilt. I had asked Harjeet and Imran on phone if he can get my Torque Converter rebuilt as well. He had said that he does in fact rebuild TCs right here in Mumbai. Now Torque Converter rebuild is not an easy job and there are just a handful of places in the world that have a success with this operation. So I was not very sure of Harjeet’s claims. Maybe he was bluffing? So I kept on an independent search of Torque Converters on eBay and Facebook etc. Now it happened that one very large firm in China is manufacturing and rebuilding TCs and I happened to contact them. The owner of the firm asked me if I have a workshop? I Told him ‘no’, but I am searching a Torque Converter for my own car. The guy asked me ‘But who is doing your rebuild’? I told him one Sehmbi transmissions in Mumbai. The guy immediately pinged me back ‘Is it Harjeet? This was now all the confirmation I ever needed.
So with the serviced but limping transmission I planned a 500Km Trip to Madh. Before I started, I took my Xentry readings. The K3 clutch which is a common clutch in the 722.9 transmission was showing very little adjustment spec left. However, the car did manage the drive all the way to Madh. I reached Madh and again took Xenty readings before I handed the car keys to Harjeet. I had lost 17% clutch fill time spec on the B1 clutch and about 5-6% spec range was remaining before the TCU would have reached its limit to adjust for the wearing clutches and the transmission would have slipped once again. I had reached Sehmbi just in the nick of time.
I was given a quote over email for the transmission rebuild which would cover everything from new clutches and brakes, solenoids, valve body, conductor plate etc. I insisted on the Torque Converter to be checked as well and if any doubts it should be addressed as well as part of the rebuild. I was told that that would be extra. And if I can arrange the Torque Converter then they would be happy to use my arranged TC or they can do it for me.
The clock started ticking, and the anticipation grew as I awaited the completion of the transmission rebuild. The time span was set at 15 days, with a few extra days allocated should the Torque Converter join the rejuvenation process. Throughout this transformative period, Imran became a reassuring presence, keeping me well-informed with weekly updates.
Finally, the moment of truth arrived, and my car was returned to me within the promised timeline. A sense of suspense filled the air as I prepared for the ultimate test: the Mumbai to Ahmedabad drive back home. Each shift was scrutinized with eagerness, and the transmission’s performance left me impressed. Smooth and seamless, it exhibited a gracefulness that is characteristic of these Transmissions from Mercedes Benz.
Months have passed since that exhilarating drive, and I find myself enjoying a successful rebuild. The transmission continues to shift flawlessly, infusing my drives with joy and confidence. Regular check-ups with Xentry confirm the stability of clutch fill times, further reinforcing the sense of reassurance.
As I cruise along the open roads, I can’t help but think of sharing my experience with others. The challenges faced, the planning, and the seamless collaboration with the service team have culminated in a positive ending. My car is back to its former glory, and every drive is a reminder of this long but satisfying journey.
Keyword: Happy experience with Sehmbi: How they rebuilt my failed E-Class AT box