Gearbox Support broken?

KevsZ4 · 03-10-2018, 01:14 PM

Hey ladies and gents,
Just wanted to see if anyone else has experienced this, and what might have caused it.

I'm looking at a purchasing a 07 E85, and everything looks good. except when we put the car up on the rack to look under it, I noticed that the gearbox support was completely broken in half! (basically a cross member that goes underneath the rear part of the gearbox to reduce torque during shifts, smoother operation, etc.)

I talked to a wise old BMW guy who says the support is just cast aluminum, probably not the best quality to begin with. So I only have 3 ideas in my head as to why this would happen:
1 - Maybe a large pothole/road condition, jarred the car so hard it snapped? We do have some crappy roads in GA.
2- Something scraped under the car, caught the front edge of it and broke it- maybe like a Raised manhole cover, etc.
3- the car was in a Carfax reported accident. Carfax specifically states minor damage to the left side? No mention of structural damage.
I think its widely understood that when a report is made indicating Minor damage, that it couldn't rise to the level of frame damage. Examples include dented bumpers, fenders, grills and body panels. And from my inspection, they've done a great job repairing whatever the damage was.

I have yet to test drive it to make sure everything checks out okay. I know PPIs are important too, but I was just curious if has anyone else had any experience with this?

Thanks for reading!
KG

Efthreeoh · 03-10-2018, 02:45 PM

I've not really studied in detail the rear trans crossmember in my E86, but I have in my other 3 BMWs. They are all pretty much of the same design and although cast aluminum, all have a decent amount of webbing to make them very strong. Generally when an engineered part like a crossbrace breaks it is because it took a force in a direction it was not designed for. Perhaps some knucklehead tried to lift the car from the trans support? If something hit it at speed, I'd imagine there would be marks on it.

SaltyNC · 03-11-2018, 08:39 AM

Quote:

Originally Posted by Efthreeoh

Perhaps some knucklehead tried to lift the car from the trans support?

This is what first came to my mind. Do you see any marks on it?

Salty

KevsZ4 · 03-11-2018, 02:14 PM

I couldn't really distinguish any particular marks on it. But the break was pretty much in the middle, and I think it was kinda bent upwards, so that does give the lift theory some legs. In any case, the part is being replaced on Tuesday, and I'll get another look under after they replace it.

After that, I'll take her for a test drive, and make sure she drives straight, the trans feel right, and all the gears work.

If so, I'l be doing this --->

joelselman · 03-12-2018, 06:50 PM

How did it drive with the broken crossmember? Smooth?

Remember, that broken crossmember placed stress on the motor mounts and rubber driveshaft guibo and possibly center driveshaft support, differential pinion, and transmission output shaft.

03-10-2018, 01:14 PM	#1
KevsZ4 Enlisted Member 11 Rep 42 Posts Drives: 03 Z4 3.0 Join Date: Apr 2016 Location: Atlanta GA iTrader: (0)	Gearbox Support broken? Hey ladies and gents, Just wanted to see if anyone else has experienced this, and what might have caused it. I'm looking at a purchasing a 07 E85, and everything looks good. except when we put the car up on the rack to look under it, I noticed that the gearbox support was completely broken in half! (basically a cross member that goes underneath the rear part of the gearbox to reduce torque during shifts, smoother operation, etc.) I talked to a wise old BMW guy who says the support is just cast aluminum, probably not the best quality to begin with. So I only have 3 ideas in my head as to why this would happen: 1 - Maybe a large pothole/road condition, jarred the car so hard it snapped? We do have some crappy roads in GA. 2- Something scraped under the car, caught the front edge of it and broke it- maybe like a Raised manhole cover, etc. 3- the car was in a Carfax reported accident. Carfax specifically states minor damage to the left side? No mention of structural damage. I think its widely understood that when a report is made indicating Minor damage, that it couldn't rise to the level of frame damage. Examples include dented bumpers, fenders, grills and body panels. And from my inspection, they've done a great job repairing whatever the damage was. I have yet to test drive it to make sure everything checks out okay. I know PPIs are important too, but I was just curious if has anyone else had any experience with this? Thanks for reading! KG
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03-10-2018, 02:45 PM	#2
Efthreeoh General 17199 Rep 18,691 Posts Drives: The E90 + Z4 Coupe & Z3 R'ster Join Date: May 2012 Location: Virginia iTrader: (0)	I've not really studied in detail the rear trans crossmember in my E86, but I have in my other 3 BMWs. They are all pretty much of the same design and although cast aluminum, all have a decent amount of webbing to make them very strong. Generally when an engineered part like a crossbrace breaks it is because it took a force in a direction it was not designed for. Perhaps some knucklehead tried to lift the car from the trans support? If something hit it at speed, I'd imagine there would be marks on it. __________________ A manual transmission can be set to "comfort", "sport", and "track" modes simply by the technique and speed at which you shift it; it doesn't need "modes", modes are for manumatics that try to behave like a real 3-pedal manual transmission. If you can money-shift it, it's a manual transmission. "Yeah, but NO ONE puts an automatic trans shift knob on a manual transmission."
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03-11-2018, 02:14 PM	#4
KevsZ4 Enlisted Member 11 Rep 42 Posts Drives: 03 Z4 3.0 Join Date: Apr 2016 Location: Atlanta GA iTrader: (0)	I couldn't really distinguish any particular marks on it. But the break was pretty much in the middle, and I think it was kinda bent upwards, so that does give the lift theory some legs. In any case, the part is being replaced on Tuesday, and I'll get another look under after they replace it. After that, I'll take her for a test drive, and make sure she drives straight, the trans feel right, and all the gears work. If so, I'l be doing this --->
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03-12-2018, 06:50 PM	#5
joelselman Private 5 Rep 59 Posts Drives: 2005 Z4, 2001 530 Join Date: Apr 2014 Location: lake havasu city, az iTrader: (0)	How did it drive with the broken crossmember? Smooth? Remember, that broken crossmember placed stress on the motor mounts and rubber driveshaft guibo and possibly center driveshaft support, differential pinion, and transmission output shaft.
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