99' Boxster Wheel Ideas

[Dave80GTSi]

Originally Posted by JFP in PA

1. Tubs are exactly the same.

2. 18" became a regular factory option in 2001 and very late production 2000 cars after the factory tub modification. And no, we are unaware of telling when the modifications become standard as it was done during the production year, so unless you know for a fact that car was delivered with 18", putting them on a 2000 runs a risk.

JFP - Not questioning, but now puzzled.

In trying to find a copy of the noted TSB for reference, my search brought forth an old 2015 thread here on this same subject:

https://986forum.com/forums/boxster-general-discussions/55502-1997-boxster-18-inch-rim-fitment-question.html

This old thread indicates that the reinforced tub came about in the year 1998 in lieu of the year 2000.

I also note that the owner's manual for my 2000 S clearly discusses both 17- and 18-inch wheels, so seemingly this would have been an option ordering box that could have been ticked back in that day.

That all being said, have you ever snapped a picture of a damaged tub? And is this entire issue more applicable for a raced / tracked car vs. one which is strictly street driven?

Thanks - DM

[997_986]

Originally Posted by Dave80GTSi

JFP - Not questioning, but now puzzled.

The document I posted is clear:

The tenth digit of the 17-digit vehicle identification number indicates the model year,
z. For example, WP0ZZZ98ZVS600001:
V = 1997 W = 1998 X = 1999 Y = 2000 1 = 2001 2 = 2002 etc.

And further above the table with the 18” wheels:
18" only for vehicles from model year 1998 (W) onwards.

So if you find a "V" in your VIN as tenth digit you are not allowed to run 18". And keep in mind that you need to stick to the mentioned dimensions and hints of the tires for 18" rims to be on the save side even if you have a MY 1998 onward!

[JFP in PA]

Originally Posted by Dave80GTSi

JFP - Not questioning, but now puzzled.

In trying to find a copy of the noted TSB for reference, my search brought forth an old 2015 thread here on this same subject:

https://986forum.com/forums/boxster-general-discussions/55502-1997-boxster-18-inch-rim-fitment-question.html

This old thread indicates that the reinforced tub came about in the year 1998 in lieu of the year 2000.

I also note that the owner's manual for my 2000 S clearly discusses both 17- and 18-inch wheels, so seemingly this would have been an option ordering box that could have been ticked back in that day.

That all being said, have you ever snapped a picture of a damaged tub? And is this entire issue more applicable for a raced / tracked car vs. one which is strictly street driven?

Thanks - DM

The copy of the TSB in our files is dated 1999 but maybe an updated version which is not uncommon in their TSB system, and we always discarded the outdated versions when the new ones came out.

To my knowledge, Porsche first acknowledged there was a problem sometime in 1998, which started the process to access it and determine an engineered fix for it. As it turned out, the best fix was to thicken the metal used in the tub bulkheads and suspension mounts to prevent the visible cracking that was the first signs of the problem. In order to do this, Porsche had to make several changes in their internal parts system, which took some time, and quite plainly they were not going to just throw out the thinner tubs after making the TSB known. The transition to the new tub started sometime in model years 1999-2000, and much like the single row/dual row IMS changeover, there was never a clear "de-embarkation" point such as a chassis number or production date, so some of the 2000 tubs were thicker metal, others were not.

When we became aware of the issue from the factory TSB, we began to take special steps when looking at pre 2001 cars. Because our state inspection permit requires us to examine critical suspension attachment points for rust out or other similar failures, and to report them to the state when we found them, we started using a crack detection penetrating fluid that was applied to the suspension mount areas of the early cars that would leave a stain if there was cracking, and we saw it on a couple of cars. During one PPI of an early Boxster, we found the entire rear bulkhead and suspension mount areas to be sprayed with an undercoating material that is not factory, and which the car owner would not allow us to scrape off to test. Suspecting something was amiss, we borrowed and ultra sonic testing device from a neighboring chassis fabrication shop and tested the metal around two of the rear suspension mounting points, both of which indicated the presence of cracking, so we told the prospective buy to walk away from the sale. We heard later that another shop passed the car for PPI for another potential buyer, but when the buyer took it to a dealer for state inspection, they also found the damage and failed the car, which resulted in an ugly lawsuit to get the original sell to buy back the car as the state pulled its registration for being unroadworthy.

As for photos of the type of damage you might find, yes we have copies of them in our computer files, but cannot release them to the public without the prior written approval of the persons that paid for the examination due to our state laws which say such materials are their property, not ours. This the exact reason why in many states, Porsche dealers will not release the service records for a vehicle.

[Dave80GTSi]

Originally Posted by JFP in PA

The copy of the TSB in our files is dated 1999 but maybe an updated version which is not uncommon in their TSB system, and we always discarded the outdated versions when the new ones came out.

To my knowledge, Porsche first acknowledged there was a problem sometime in 1998, which started the process to access it and determine an engineered fix for it. As it turned out, the best fix was to thicken the metal used in the tub bulkheads and suspension mounts to prevent the visible cracking that was the first signs of the problem. In order to do this, Porsche had to make several changes in their internal parts system, which took some time, and quite plainly they were not going to just throw out the thinner tubs after making the TSB known. The transition to the new tub started sometime in model years 1999-2000, and much like the single row/dual row IMS changeover, there was never a clear "de-embarkation" point such as a chassis number or production date, so some of the 2000 tubs were thicker metal, others were not.

When we became aware of the issue from the factory TSB, we began to take special steps when looking at pre 2001 cars. Because our state inspection permit requires us to examine critical suspension attachment points for rust out or other similar failures, and to report them to the state when we found them, we started using a crack detection penetrating fluid that was applied to the suspension mount areas of the early cars that would leave a stain if there was cracking, and we saw it on a couple of cars. During one PPI of an early Boxster, we found the entire rear bulkhead and suspension mount areas to be sprayed with an undercoating material that is not factory, and which the car owner would not allow us to scrape off to test. Suspecting something was amiss, we borrowed and ultra sonic testing device from a neighboring chassis fabrication shop and tested the metal around two of the rear suspension mounting points, both of which indicated the presence of cracking, so we told the prospective buy to walk away from the sale. We heard later that another shop passed the car for PPI for another potential buyer, but when the buyer took it to a dealer for state inspection, they also found the damage and failed the car, which resulted in an ugly lawsuit to get the original sell to buy back the car as the state pulled its registration for being unroadworthy.

As for photos of the type of damage you might find, yes we have copies of them in our computer files, but cannot release them to the public without the prior written approval of the persons that paid for the examination due to our state laws which say such materials are their property, not ours. This the exact reason why in many states, Porsche dealers will not release the service records for a vehicle.

Thank you for taking the time for your interesting (and insightful!) reply! - DM

[mikefocke]

I had somehow acquired this in my list of model year differences "18” wheel option with rear chassis reinforced to accept new wheels. Rear body structural change included redesigned wheel wells and coil spring mounts, lower engine compartment bulkhead, rear wall crossmember and rear axle mount reinforcements." as a 1998 change.

Has anyone anything definitive that contradicts that date? I always assumed people were putting on bigger wheels and going racing and the defects showed so Porsche did an improvement but I don't know where I came up with the date as that was written years ago.

[Hamstuh]

"In 1998, Porsche added some reinforcement in the rear monocoque structure, which was supposedly required to allow running 18" wheels. Other than that there is absolutely no difference that I can tell in any 986 or 987 Boxster or Cayman suspension."

This was something i found randomly doin some digging, wonder if thats the case maybe it would be fine ? Im only stubborn with this topic bc it seems the market for porsche wheels are GREATLY higher in 18'' rims and im not a track driver so idc for small differences in performance from a 17 to an 18.