Transmission damage from rear end collision while car was parked?

subaru
legacy

#1

We have had problems with clutches going bad on our Subaru legacy ever since it was rear-ended while sitting parked in 1st gear (standard transmission) with the hand-brake on in our driveway. The car was moved forward 3 car lengths by the direct hit to the rear end. The car suffered obvious body damage which was paid for by the driver’s insurance. But we noticed that the clutch did not seem the same after the accident. We asked if the accident could have damaged the clutch or transmission but were told it would not and so it was not really looked into.

A few years later, the clutch failed completely with only 43,000 miles on it (16,204 more than when it was hit). We again raised the concerns that the clutch did not seem the same even after replacing it (including flywheel) and throw-out bearing but were told there was no problem. The clutch failed again suddenly in this year with only 22,000 more miles since the clutch replacement in 2010. This time the repair shop tore down the transmission and clutch and told us that the throw-out bearing had seized due to high temps within the transmission and also showed us evidence of unusually high temperature-related damage to the clutch disk, plate and flywheel. They said that the nature of the damage was similar to what they had seen when the clutch was replaced in 2010 and that there was something inherently wrong with the car which had resulted in two clutches being severely overheated and that the transmission may also be damaged and need to be replaced. They also told me that this type of overheating would not happen just from a driver riding the clutch (which we don’t do).

Does anyone have any insight into whether the two clutch failures may be related to damage caused by the initial accident? Here are some pics of the damaged parts.

Thanks!


#2

Looking at the images I can see the boss where the throwout bearing rides is all gouged up. This could be preventing the throwout bearing from pressing squarely onto the pressure plate. And if the pressure plate isn’t fully releasing the clutch disc the clutch isn’t going to last very long.

And if you look at the ends of the diaphram fingers on the pressure plate, you can see they got hot. And there’s actually material being wiped off the fingers at one side.

And that thowout bearing shouldn’t look like that.

Was the damage caused by the accident? I can’t say.

Tester


#3

Hard to say what exactly could be damaged when the car is struck that violently. But with the transmission engaged in 1st gear, it couldn’t have done any good to the clutch or the transmission. Whether it damged them, well, without the benefit of a controlled experiment, it’s like determining how many angels could fit on the head of a pin. Tough to say.


#4

Yes, a transmission can be severely damaged from an impact and this does look like a heat related failure of the throwout bearing which was not releasing.

Note that in the first and fourth pictures in the top row there are gouges in the circumference of the transmission mainshaft snout. Those gouges can cause the TO bearing to hang, keep it spinning, and which will eventually cause failure. That snout is part of the transmission case halves and made of comparatively soft aluminum so the snout can be easily damaged.

Sometimes those gouges can be caused by wear due to a grease groove in the TO bearing guide sleeve (depending upon year/model) or by the collision. The miles on your car are a bit low for a wear issue but it all depends… :frowning:

The shop should take, or should have taken, the snout factor into consideration during a clutch replacement; making sure there are no flaws and the TO bearing slides freely and without wobble on the transmission snout.
There’s a repair kit which can be had and which consists of a new TO bearing and sleeve for the snout. The sleeve is similar to a Speedi-Sleeve which is used to counteract engine crankshaft oil seal wear grooves and prevent oil seal leakage.
Sorry I can’t be more definitive about who did what but hope some of that helps anyway.


#5

There is no apparent impact damage. The throw out bearing would indicate excessive idling with the clutch disengaged or zero free play at the bearing. The discoloration indicates excessive heat that would result from the clutch slipping for any of the possible causes. The torque springs in the clutch disc would seem to be the first thing to fail in a collision as described yet that disc survived 16,000 miles after the impact.

And I wonder how many miles the car was driven with a noisy, rough throw out bearing before the bearing finally disintegrated and left the car undriveable?