[dakotap80]

Heyo, so I was going to put my car on jack stands at each corner but when I went to jack from the rear cross member I noticed that this metal rod was directly under the middle of the cross member blocking the jack. It looks like it's just a brace between each of the exhaust pipes, and the pipes are supported within a foot up and downstream of the brace.
Can I just cut this rod out of the way or will my exhaust pipes rattle around really badly if I do that? Car is an N55 if that makes any difference. Thanks!

[hassmaschine]

Just jack it up from the diff.

[gbalthrop]

Originally Posted by dakotap80

...Can I just cut this rod out of the way or will my exhaust pipes rattle around really badly if I do that? Car is an N55 if that makes any difference.

Have NO idea (1) what the metallurgical properties of that rod are, (2) what it would take to cut it, or (3) what damage to the exhaust system that might cause.

What I can say is that BMW has NOT done a good job of describing WHERE to jack at the center rear. The TIS procedure below suggests that the Trolley Jack should NOT be placed under the Rear Cover of the Differential, and SEEMS to ME to suggest that it also should NOT be placed under that subframe cross-member above the Rod you are concerned with. NOTE the X at that point which appears to me to show the subframe member rather than the Rear Cover of the Differential.
https://www.newtis.info/tisv2/a/en/e...-guide/I2a5leg

Regardless of one's interpretation of the TIS Procedure, it DOES clearly show an arrow indicating a permissible jacking point under the Differential below the Output Shafts (as HassMasch suggests ;-)

I notice you have the front wheels on ramps. If you are looking to get the vehicle level to change Transmission or Transfer Case fluid, you can simply jack each rear wheel at the Rear-Side body jacking points, and place 2nd pair of jack stands or pedestals under rear wheels. I have done that, for that purpose, and NOT jacked under the differential.

You may find it easier to do it in two stages, putting 3" pedestal (two pieces of 2"x10") under one rear wheel, then jacking other side to full 6" and placing pedestal on that side; followed by rejacking first Rear-side and placing 6" pedestal there. You now have level & elevated vehicle that will be stable with motor running (which you need for Transmission Fluid Level check).

George

[Welcome to NBA Jam]

Originally Posted by gbalthrop

What I can say is that BMW has NOT done a good job of describing WHERE to jack at the center rear.

I don't think the TIS can be any clearer than an arrow pointing to exactly where you can lift it.

[Efthreeoh]

How to lift the E9X chassis has about as much crap discussion as oil threads do.

[gbalthrop]

Originally Posted by Welcome to NBA Jam

I don't think the TIS can be any clearer than an arrow pointing to exactly where you can lift it.

I agree with "F30" and don't want to start a "frame/flame war" over the center-rear lift point. I agree the Arrow clearly shows a permissible lift point under the Differential, below the output shafts.

My questions are:
1) Does the "X" under the rear cover (or subframe) suggest that there is a problem with jacking by the subframe BEHIND the Differential Rear Cover?
2) Is there any reason NOT to jack by that rear subframe behind the Differential Rear Cover (OTHER than the fact OP's vehicle has a Rod in the way)?

I have heard differing opinions on that in threads here in the last year, WITHOUT any support for the opinion.

Just asking,
George

[TheMidnightNarwhal]

Originally Posted by gbalthrop

I agree with "F30" and don't want to start a "frame/flame war" over the center-rear lift point. I agree the Arrow clearly shows a permissible lift point under the Differential, below the output shafts.

My questions are:
1) Does the "X" under the rear cover (or subframe) suggest that there is a problem with jacking by the subframe BEHIND the Differential Rear Cover?
2) Is there any reason NOT to jack by that rear subframe behind the Differential Rear Cover (OTHER than the fact OP's vehicle has a Rod in the way)?

I have heard differing opinions on that in threads here in the last year, WITHOUT any support for the opinion.

Just asking,
George

The X in TIS just means to not lift diff cover since it can bend it.

As to why not to lift by subframe brace I don't know. If it's really a subframe piece I would suppose it's safe but idk.

[Efthreeoh]

Originally Posted by gbalthrop

I agree with "F30" and don't want to start a "frame/flame war" over the center-rear lift point. I agree the Arrow clearly shows a permissible lift point under the Differential, below the output shafts.

My questions are:
1) Does the "X" under the rear cover (or subframe) suggest that there is a problem with jacking by the subframe BEHIND the Differential Rear Cover?
2) Is there any reason NOT to jack by that rear subframe behind the Differential Rear Cover (OTHER than the fact OP's vehicle has a Rod in the way)?

I have heard differing opinions on that in threads here in the last year, WITHOUT any support for the opinion.

Just asking,
George

The subframe can be used. The diff bolts into it. You loose about 4 inches in jack height though.

Car ramps on the other hand frighten me. NFW I'd get under a car on ramps.

[gbalthrop]

Originally Posted by Efthreeoh

[1] The subframe can be used. The diff bolts into it. You loose about 4 inches in jack height though.

[2] Car ramps on the other hand frighten me. NFW I'd get under a car on ramps.

I suppose concepts are often NOT updated when technology changes. I have had cars with Independent Rear Suspension since 1966 with TR-4A IRS and then 1969 with Jag XK-E followed by similar IRS with XJ-6 and XJ-S. The Jags all had "Tie Plates" under the rear Differential, and it was permissible to place a wood block on the tie plate, NOT the Diff itself, to lift the rear, and I have done that MANY times. I always had the concept that you did NOT want to apply compressive forces to the Differential at ANY point -- just never thought it through or examined the differences in design between various IRS Diffs to understand WHY/IF my concept was accurate.

Seems like there are several basic considerations for jacking at or near the Differential:
1) Don't let anything slip so that Driveshaft/ Pinion Bearing area is damaged, or Output Shaft/ Drive Axle Area is Damaged, or YOU are terminally damaged;
2) Don't apply compressive forces to the Differential in such a way that the case or Rear Cover, or their sealing areas are cracked or bent.
3) Don't bend/displace anything in the subframe that holds the differential, which might affect alignment, vibration, noise, etc.

RAMPS:
As to my concept of getting under a car supported by jackstands vs. supported by ramps, my concept is the opposite of yours, so maybe you can offer some facts that I should consider to change that concept.

I have used BOTH ramps and Jackstands for different projects over many years. I have NEVER felt unsafe under a vehicle on Ramps, or even under an XJ-6 with about 12" of lumber (six 2"x12" sections ~ 18" long stacked on top of each other) under each tire so I could extract/ install an "over-axle" rear muffler & joined pipe.

My concept is that a car resting on ramps (whether the old-style steel ramps or current plastic ramps like Rhino or Magnum 16000) is actually MORE stable, particularly with motor running as required for Auto Tranny Fluid Fill, than if supported by Jack Stands.

The XJ-S V-12 was designed and built BEFORE COP Ignition and had the old Centrifugal and Vacuum advance system in a distributor for which timing was adjusted by rotating the distributor body. The timing specification for that engine is 18 Degrees BTDC with vacuum hose removed (NO vacuum advance) at 3,000 RPM). The timing marks are UNDER the Crankshaft Pulley.

So you put the front wheels on ramps, set the HANDBRAKE to THREE GRUNTS, assure yourself this is NOT a 1980 Audi that killed xx people with transmission shifting OUT of Park on its own, check to make sure your life insurance is in effect, clamp the throttle at 3,000 RPM and crawl under to have a look while the engine roars away above you. It's been nearly 20 years since I last did that, but suffice it to say, that gives you respect for thinking about all the "what-ifs" and taking all due precautions.

So if you have had any "untoward events" with ramps, or know of anyone who did, please enlighten me. I can't "bench" two tons.

George

[dakotap80]

After looking other threads about jacking the rear up I realize what a can I've worms I've opened, my apologies everyone haha.

[Efthreeoh]

Originally Posted by gbalthrop

I suppose concepts are often NOT updated when technology changes. I have had cars with Independent Rear Suspension since 1966 with TR-4A IRS and then 1969 with Jag XK-E followed by similar IRS with XJ-6 and XJ-S. The Jags all had "Tie Plates" under the rear Differential, and it was permissible to place a wood block on the tie plate, NOT the Diff itself, to lift the rear, and I have done that MANY times. I always had the concept that you did NOT want to apply compressive forces to the Differential at ANY point -- just never thought it through or examined the differences in design between various IRS Diffs to understand WHY/IF my concept was accurate.

Seems like there are several basic considerations for jacking at or near the Differential:
1) Don't let anything slip so that Driveshaft/ Pinion Bearing area is damaged, or Output Shaft/ Drive Axle Area is Damaged, or YOU are terminally damaged;
2) Don't apply compressive forces to the Differential in such a way that the case or Rear Cover, or their sealing areas are cracked or bent.
3) Don't bend/displace anything in the subframe that holds the differential, which might affect alignment, vibration, noise, etc.

RAMPS:
As to my concept of getting under a car supported by jackstands vs. supported by ramps, my concept is the opposite of yours, so maybe you can offer some facts that I should consider to change that concept.

I have used BOTH ramps and Jackstands for different projects over many years. I have NEVER felt unsafe under a vehicle on Ramps, or even under an XJ-6 with about 12" of lumber (six 2"x12" sections ~ 18" long stacked on top of each other) under each tire so I could extract/ install an "over-axle" rear muffler & joined pipe.

My concept is that a car resting on ramps (whether the old-style steel ramps or current plastic ramps like Rhino or Magnum 16000) is actually MORE stable, particularly with motor running as required for Auto Tranny Fluid Fill, than if supported by Jack Stands.

The XJ-S V-12 was designed and built BEFORE COP Ignition and had the old Centrifugal and Vacuum advance system in a distributor for which timing was adjusted by rotating the distributor body. The timing specification for that engine is 18 Degrees BTDC with vacuum hose removed (NO vacuum advance) at 3,000 RPM). The timing marks are UNDER the Crankshaft Pulley.

So you put the front wheels on ramps, set the HANDBRAKE to THREE GRUNTS, assure yourself this is NOT a 1980 Audi that killed xx people with transmission shifting OUT of Park on its own, check to make sure your life insurance is in effect, clamp the throttle at 3,000 RPM and crawl under to have a look while the engine roars away above you. It's been nearly 20 years since I last did that, but suffice it to say, that gives you respect for thinking about all the "what-ifs" and taking all due precautions.

So if you have had any "untoward events" with ramps, or know of anyone who did, please enlighten me. I can't "bench" two tons.

George

Well since you asked. 1972. Bethesda, Maryland. Young 10 year old boy (car nut) hanging out with his older brother. Broke the rear u-joint on his brother's 1944 Willy's Jeep four-wheeling on what is now the head quarters of Lockheed Martin Corporation (the old Davis Farm). Said pair drove the jeep home on the front drive. Said pair parked the jeep on the edge of the backyard basketball court to get a better look. Older brother turned the yoke on the transmission. Said jeep slipped out of gear and ran over the arm of the younger brother (could have been his head just as well).

The younger brother now uses a 2-post lift to work on cars. When cars are on their wheels, they can roll off ramps or (just 2) jackstands. When the car is properly lifted on 4 stands with wheels off the ground, the vehicle can not roll. Show me anyone, except The Rhino, Spiderman's arch enemy, who can knock a car off 4 jackstands turning a wrench on it. When one of my cars is on my lift, set on the locks, I'd sleep under it an not lose a wink.

Detail of Bethesda added so you can google.

[TheMidnightNarwhal]

Originally Posted by Efthreeoh

Well since you asked. 1972. Bethesda, Maryland. Young 10 year old boy (car nut) hanging out with his older brother. Broke the rear u-joint on his brother's 1944 Willy's Jeep four-wheeling on what is now the head quarters of Lockheed Martin Corporation (the old Davis Farm). Said pair drove the jeep home on the front drive. Said pair parked the jeep on the edge of the backyard basketball court to get a better look. Older brother turned the yoke on the transmission. Said jeep slipped out of gear and ran over the arm of the younger brother (could have been his head just as well).

The younger brother now uses a 2-post lift to work on cars. When cars are on their wheels, they can roll off ramps or (just 2) jackstands. When the car is properly lifted on 4 stands with wheels off the ground, the vehicle can not roll. Show me anyone, except The Rhino, Spiderman's arch enemy, who can knock a car off 4 jackstands turning a wrench on it. When one of my cars is on my lift, set on the locks, I'd sleep under it an not lose a wink.

Detail of Bethesda added so you can google.

I mean using ramps the proper way would be to chock the rear wheels which wouldn't let it roll... but I am also a proponent for for stands over ramps.

[gbalthrop]

Originally Posted by Efthreeoh

...1972...10 year old boy (car nut) hanging out with his older brother...Older brother turned the yoke on the transmission. Said jeep slipped out of gear and ran over the arm of the younger brother (could have been his head just as well).

Well, L'il Bro, how's that arm 47 years later? Glad it wasn't your head.

George

[Emilime75]

Just because some dude was careless back in 1972 and didn't take some, really simple, mind you, precautions, is no reason to write them(ramps) off.

You might as well write life off, in that case.

I've been using the plastic ones since I bought my Suburban in 2010. That thing weighs roughly 1800lbs MORE than my E92 335i. I've never once felt unsafe while using them.

[hassmaschine]

How about this - I swapped the entire drivetrain out of my E30 using jackstands *and* ramps - and it was on gravel!

Thankfully, my days of crawling around on my back in the dirt and rocks are long past.

[Efthreeoh]

Originally Posted by gbalthrop

Well, L'il Bro, how's that arm 47 years later? Glad it wasn't your head.

George

Well, my fastball isn't what it used to be...

[gbalthrop]

Originally Posted by Efthreeoh

Well, my fastball isn't what it used to be...

At 57, or even 47 (unless you're Nolan Ryan), MOST people have that issue, and it's usually related to the Rotator Cuff.

George

[Efthreeoh]

Originally Posted by gbalthrop

At 57, or even 47 (unless you're Nolan Ryan), MOST people have that issue, and it's usually related to the Rotator Cuff.

George

Tell me about it.

[Efthreeoh]

Originally Posted by dakotap80

After looking other threads about jacking the rear up I realize what a can I've worms I've opened, my apologies everyone haha.

Well, after all, you kinda asked a... question.

Just sayin'

[Efthreeoh]

Originally Posted by Emilime75

Just because some dude was careless back in 1972 and didn't take some, really simple, mind you, precautions, is no reason to write them(ramps) off.

You might as well write life off, in that case.

I've been using the plastic ones since I bought my Suburban in 2010. That thing weighs roughly 1800lbs MORE than my E92 335i. I've never once felt unsafe while using them.

Well, in 1972 I didn't feel unsafe laying under a Willys Jeep parked with the front wheels on a raised concrete slab with the transmission in gear UNTIL moving the transmission output shaft slipped the transmission into neutral...

And sure, I can go find and post pics of cars that have fallen off a car lift too. You can't out engineer dumbass, but you can engineer in safety. An E90 sitting on top of 4 flat-top jack stands with the wheels off the ground is safer than an E90 on ramps.

[Efthreeoh]

Originally Posted by hassmaschine

How about this - I swapped the entire drivetrain out of my E30 using jackstands *and* ramps - and it was on gravel!

Thankfully, my days of crawling around on my back in the dirt and rocks are long past.

Amen on that! Pulled the 2L out of my Pinto one sub-freezing January day on a gravel driveway. Maybe that's why the shop has a 100,000 BTU furnace hanging from the ceiling...

[dakotap80]

Originally Posted by Efthreeoh

Well, after all, you kinda asked a... question.

Just sayin'

Totally fair. I just didn't realize it was such a dumb question