IMS Retrofit Classic vs. Pro

I found out this morning that a 2004 C4S that I was planning to purchase has the LN IMS "Classic" retrofit instead of the "Pro." It's been in there for 18,000 miles, so I'm assuming we can rule out a failure due to improper installation or debris in the sump. I have the RO from 2013 when the work was done, and all indications are that this was preventative - not a repair. The total bill, including the clutch, RMS, and a couple other minor items was just over $3,000. So, the question I have is whether I should give pause to the fact that this is a classic, not a pro. I was really thinking that I'd have a very long-term solution in there, not a one that's up against its 4-year service interval. I could roll the dice and focus on the 50,000 mile side of the service interval, but that's an expensive roll of the dice. Thoughts?

Depends what you want out of the car. I'd happily buy a car with the retrofit if it was just done as a PM, but it also depends if the car ticks some other boxes I'd be looking for as well.

If you consider the single row pro to be a permanent solution and the single-row bearing to be a stop-gap or interval maintenance item, I guess it would make sense to be concerned by this information. I'm one of those fear-mongers; I wouldn't be buying a single-row car without also planning to immediately have the Solution installed - so it wouldn't matter to me which (original, single row retrofit, single row pro retrofit) bearing was present. Since it sounds like you don't plan to replace the IMS bearing any time soon, I'd hold out for a dual-row car, a Pro-retrofitted single-row car, or one that's already been Solved. Unless you're already in love with a car, why pick one from the group more likely to suffer an IMS-related failure? I'm not knocking the car, nor trying to stir up concerns. OP wants a car with "a very long-term solution" already in place. A single-row IMS bearing is the least long-term of all 996 IMSB solutions.

I take the following view the classic installed properly in a well maintained car with frequent oil changes is a service item that should be changed out every time the clutch needs doing . or equivalent mileage on a tip. if that was my car , I'd keep regular ( every 6 months ) oil changes and do it next clutch or if concerned And couldn't sleep , change it at the 50,000 mile interval . the pro is a service item that needs doing every other clutch . and the solution is a service item that you change ( or inspect and replace if bearing shows wear ) with every engine rebuild . In most cases it should outlast the car .

Fwiw , my 2004 c2 car had the classic installed 3 years ago and 10000 miles later I'm not worried about the 4 year mark , I'll change it when the clutch needs doing , I will probably go with the pro or solution at that point

I had a Classic Single-row installed in mine at 30K. 32K miles later it had not failed. However the engine needed replacement due to bore scoring. New engine has Solution, which is the only product I would consider at this point in time. When I had mine done, the Classic was all there was.

My car has LN Engineering single row kit installed 10000 miles ago. Since manufacturer says change interval is 75000 miles / six years I feel safe. Current mileage is now 86000 ...

LN doesn't even appear to sell the single-row kit any more, and I believe - but won't swear to it - that the recommended interval dropped significantly.

LN still has both the single and double row retrofit kits on their website and the Solution for both singe and double row.

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My clutch will be gone way before IMS needs to be replaced (knocking on wood). Dual row kit will be in at that time for sure ...

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LN has the dual-row and the single-row pro for sale. I did not see the old (non-Pro) single row bearing for sale any longer.

If the classic single was installed by an authorized installer then I would leave it in until next clutch.

Thanks everyone. I picked the car up today, and a I had a blast driving it all afternoon. The seller was surprised that it has the classic bearing in there and knocked some money off the price we had previously agreed upon. I'll keep my fingers crossed until I get a Solution or Pro involved down the road. Thanks, all, for your thoughts. I suspect I'll get asked for a pic, and I'll post one tomorrow when I get a chance to take a beauty shot. C4S Cabriolet Seal Gray / Natural Brown.

Way to go! My 2c: I’d much prefer to get the IMS Solution installed myself then to rely on somebody else. So, the choice you made now is perfect; it’s got a temporary solution that will allow you to drive it without too many worries about the IMS for the next 1-2 years. If you by then still want to drive the car longterm, get the IMS Solution and be done with it. In the meantime you can focus on some other stuff like replacing AOS and waterpump etc. Volkert

So far, so good. I got to spend the last couple days checking out some great coastal NorCal roads in beautiful weather. I can certainly see how people become such fans of these cars.