The first thing that comes to mind when people think of Porsche ownership is usually maintenance costs. While in some cases this may be very true, it's not necessarily always the case. Here's a little story I'd like to share.

It's no secret my 1984 911 STR build has been done on a budget. Projects like my $8 strut bar and $105 exhaust are a testament to that. But I'm also not opposed to spending money for the good stuff where it counts. Take my program, for example.

In competition, I'm reaching a wall with the car. I'm having problems putting power down coming out of corners, and I'm having to drive around instability on deceleration. I'm thinking about spending the money to put a Limited Slip Differential, or LSD in the car. An LSD can be set up to lock up to a degree under both power and deceleration, which would help with both of those problems.

A story about Porsche maintainence costs

This will be by far the largest expenditure in the project so far. Not only is a quality LSD unit expensive, it needs to be installed, too. That's where our story begins.

On most RWD cars, the diff sits in a pumpkin in the back and is relatively easy to access. The 911, of course, has a transaxle mounted between the seats. So it's more like a fwd car in that the whole transmission needs to be removed to install an aftermarket differential. I think I can handle that part. What gets over my head quickly is the install itself. Ring and pinion setup isn't total rocket science, but it is to me. The pinion depth, gear lash, and preload on the side bearings has to be all just right or you'll have a noisy transmission and possibly wear out your R&P and bearings very quickly. That would be expensive.

A story about Porsche maintainence costs


Here's an excellent writeup on the procedure, which solidified that it was something that I should have done professionally.

Disclaimer: I fully understand that hourly rate for a regular mechanic is up in the $80-$100/hr range these days. I think that's fair, too. I understand that's not just hourly labor rate, but also overhead and amortization for all the specialty tools and training a mechanic needs.

I also understand that a mechanic with intimate specialized knowledge of a 30 year old classic car is darn near priceless, and well worth a higher hourly rate. I'm not looking for a $200 install here.

So I did what anyone else would do - Googled "Porsche mechanic" and blasted out a bunch of emails:

Do you guys still have the tools / procedure to install an LSD in an otherwise good condition 915 transmission? I'm thinking about picking up an aftermarket unit and looks like setting pinion depth / lash / preload is beyond my ability.

I would be bringing in just a bare transmission. I know it's hard to give a quote, but any idea of about how many hours of job time this would be? I'd like to know how many pennies I need to shake out of my ceramic pig.



I chose my words carefully. I wanted to present myself as knowing at least a little what I was talking about, even if all I really knew was what I read in the link above. One of my responses came from Bob at what will remain an unnamed Porsche shop:


Yes, we could do this for you. I would budget $500 labor. I would also suggest/budget new diff carrier bearings/output bearings, a set of bolts and tabs for bolting lsd to the ring gear and possible shims. Budget for additional parts would be app $700. Let me know what you would like to do.


$500 for labor sounds more than fair to me. If I bring in a bare transmission, that translates to maybe 4 hours at $125/hr. To pull the side cover, replace the bearings, install the diff, and set the spacing seems totally reasonable. BUT CHECK OUT THAT PARTS VALUE. Wha-wha-wha?

$700? For some bearings, bolts, and shims? Ok, breathe. And behold the power of the internet. is a pretty awesome parts website, interactive, easy to look stuff up, and good prices if the shipping sometimes is a little rough. It took me two minutes to find that the diff bearings are 32010X bearings, which are off the shelf units also used in Honda and VW cars that run from $21-$31 each depending on brand.

A story about Porsche maintainence costs

Ok, so $50 for bearings, maybe $30 for a set of ring gear bolts, and a few shim washers that can't cost more than a few dollars each. I'll even allow $100 for misc sealants or gaskets or something that might need to be in there - and that's being generous. That's $200 in parts, at the most. But $700? I had to ask:

That's a little bit of sticker shock on parts - 32010X carrier bearings look like they're about $50/pair, can't imagine ring gear bolts and shims being all that bad.
I know you never know until you get in there, but is that $700 estimate a worst case scenario, like if my race bores are jacked or if the pinion is out of whack?

Again, I chose my words carefully. I wanted to tip my hand that I still knew at least a little, and also give Bob an out to explain himself and/or backpedal. It's totally possible that there is something about installing a differential in a 915 that I am unaware of.

It took a few days, but today I got a response from Bob:


I am sorry for the delay in responding. Based on our present workload, this is not a job we are able to take on.

THank you for the inquiry,


BWAHAHAHAHA! Nice try Bob.

I don't want to be a cynical person. I really don't. But I can't help but feel that Bob is one of those people who preys on the uninformed. I could be wrong. But I doubt it. I'm sure that there have been many, many Porsche owners who simply take an estimate like that and accept it as "well, it's a Porsche, it should be expensive to maintain." Maybe even that's how such a reputation develops.

What Bob doesn't understand is that he is bad for the legacy of the car. How many people brought their pride and joy 911 in for a little work and got an artificially high estimate? And how many people sold their cars right after that thinking they cost too much? Shame on you Bob, and all the Bobs like you out there.

I browsed 911 ads for years before buying my car. One of the sales points that comes up often is something along the lines of "Over $7000 is receipts for recent maintenance!" The numbers on those totals often seemed a little high to me, almost regardless of what was done. Maybe now I understand why.

Since you're probably a little upset after reading this (I know I am after typing it) here's a puppy to help calm you down.

A story about Porsche maintainence costs

Slightly edited from my original version at