Piston Slap: To What End Unibody Repair?

Sajeev Mehta
by Sajeev Mehta
piston slap to what end unibody repair

Matt writes:

Hi Sajeev, Long-time listener, first-time caller. I have a 2011 Volvo C30 that was recently rear-ended pretty good. As a result of the collision, the car has just had $8k+ of work done in a body shop. Included in the list of work done (among the obvious paint, bumper cover, tailgate, etc) is 4 hours of labor for a “unibody pull”. Like everyone else, I know people who have horror stories about cars that have never been the same again after accidents. I’ve only had the car back for a couple of days and everything feels ok so far, but I do fear lingering issues.

What are your thoughts on a repair like this making the car 100% again? Would you dump it immediately to avoid any potential issues or hold on to it and see?

Sajeev answers:


Oh boy. As Reverend Lovejoy from The Simpsons would say, “Short answer yes with an if, long answer no with a but.”

Short Answer: Too many variables to consider, so you must hope the collision center and the insurance company are both honest in their damage assessment and intelligent in their repair procedures. Those with frame repair issues probably had a problem with human error.

Long Answer: We have the technology to repair just about any car, but doing so requires a cost/benefit analysis. For many cars, if the roof shows signs of structural damage, your insurance company will happily scrap it for you. And if you are a wannabe Gas Monkey with an absolutely hammered Ferrari F40, you buy that heap at auction, make it into a rolling death trap and sell it again. But that’s not the point…

An honest assessment from a collision center with proper frame straightening tools easily measures and tweaks the frame until every part is back to factory specifications. All the doors close perfectly. The wheels sit just where they should. Everything bolted up back as designed. And back to the short answer, it boils down to the quality of decisions made by the people involved.

I remain optimistic that your repair was sound, that you’ll enjoy this Volvo for years to come with zero problems.

UPDATE: The B&B brought up a great point, making a diminished value claim. Definitely consider this, you won’t regret it.

Send your queries to sajeev@thetruthaboutcars.com. Spare no details and ask for a speedy resolution if you’re in a hurry…but be realistic, and use your make/model specific forums instead of TTAC for more timely advice.

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  • C71 C71 on Dec 12, 2013

    Hi all, This was my question - thanks for the responses. Not surprisingly, there's no consensus on this one, but I guess that's to be expected considering I don't really know the quality of the repair. I'm still on the fence about whether to keep the C30 or not, partially because there are no other (affordable) cars out there I'm terribly excited about. (Ford, seriously, you lost a Fiesta ST sale by making MyTouch non-optional) The C30 still mostly seems fine. The only possibly worrying thing I've started to notice is a slight shimmy while braking lightly, which is probably just a brake rotor or alignment issue. I'm just a few hundred miles away from my 45k mile service so I'll get that checked out soon. I did pursue a diminished value claim - I got a couple dealers to write up trade-in quotes with a current offer as well as a note stating how much they would have been willing to pay had the accident not occurred. These values were closer than I would have thought - the current trade-in offers were about $2000 less than the "clean" trade-in values. I settled with the insurance company for $1500 diminished value. I didn't feel the need to press the issue beyond that because they'd also given me some "pain and suffering" money.

    • See 4 previous
    • Rpn453 Rpn453 on Dec 16, 2013

      My 2004 Mazda3 got T-boned a few years ago by a young girl on a cell phone who treated a red light as a four way stop and had absolutely no memory about anything directly preceding the collision. About $10k worth of damage. They replaced the rocker panel, both doors, the front fender, and the tie rod and tie rod ends. Considerably later, I noticed that I would get some vibrations in the steering and brake pedal under hard braking at highway speed. Not something I do often and enough time had passed that I didn't think to attribute it to the collision. I just figured the rotors were a little out. A few years later, I notice fluid leaking from one of the control arm bushings. I wasn't too upset, as I'd been wanting to put some stiffer bushings on anyway to reduce wheel hop. When I went to remove the front bushing on the damaged side, I was surprised to find the bolt was already loose but would not thread out more than a turn or two. I had to cut the bolt out with a sawzall - consuming many blades in the process - and found that the bolt had been bent, certainly by the collision. With new performance bushings and a new bolt, that part of the car is better than ever. But the driver's door still doesn't close as well or sound as good doing it. Suspension damage is probably not applicable to you after a rear-end collision, but I figured I'd tell the story anyway since you reminded me of it! I'm not concerned about any loss in resale value because I bought the car new with no intention to ever sell it. I've seen no evidence of shoddy workmanship or premature rust yet on the paint or bodywork.

  • Jimbob457 Jimbob457 on Dec 13, 2013

    One oft quoted rule of thumb is that repaired vehicles with salvage titles sell on average at a discount of 25% compared other examples of the same mileage and apparent condition.

  • KOKing I car-sat an A32 while its owner was out of the country, and the then whiz-bang VQ motor was great, but the rest of it wasn't any better than a XV10 or XV20. Definitely the start of its downward slide, unfortunately.
  • Norman Stansfield Why are leaf springs still a thing on this truck?
  • Syke The expected opening comments. Have had mine for two years now, the car has done exactly what I want out of it, and a little better. I'm quite happy with the car, haven't had to adjust my driving style or needs in the slightest, and . . . . oh, did a mention that I don't give a damn what today's price at the pump is?Probably going to go for a second one in the coming year, the wife's happy enough with mine that she's ready and willing to trade in the Nissan Kicks. Eventually, the not often used van will end up getting traded on a Chrysler Pacifica Hybrid, basically ensuring that we don't use gas for anything except the occasional long trip.And the motorcycles.
  • Bobbysirhan I've never found the Allegro appealing before, but a few years of EV rollouts make it seem downright desirable.
  • Scoutdude I know that dealership. Way back when my friend's grandfather was that Turner that owned the Chrysler Plymouth International dealer, in MacPherson. Of course the International was dropped when they didn't deem the Scout reason enough to keep the franchise. I moved from there in late 1978 so it is possible I saw this running around town way back when.
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