Author Topic: FRONT SUBFRAME BUSHINGS, MOTOR MOUNTS / replacement  (Read 2193 times)

Bshaunessy

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FRONT SUBFRAME BUSHINGS, MOTOR MOUNTS / replacement
« on: October 02, 2022, 14:11:35 »
SL  COMMUNITY:
  Hoping for some clarity on process to replace front subframe bushings (2) and motor mounts (2) as I’ve tried, unsuccessfully.   (1970 280 SL).  NB: I have studiously read and studied every post RE subframe bushings…..main issue is insufficient clearance between body and front spring to get old busing out ( and new one in!)

MY PROCESS:
(1) car on hoist, supported by body at the four subframe to body lift points.  Wheels off.
(1.5) engine supported independently using transmission Jack and wood blocking.
(2) working just one side at a time, started with drivers (left) side
(3) undid shock absorber
(4) undid subframe bushings "bump" plate (4 x m8 bolts)
(5) undid subframe bushing centre bolt (17mm…. Had to use impact gun /WD 40….very rusty…time to replace!)
(6) At this point, can access old subframe bushing at top of spring BUT insufficient room to worm bushing out  of gap between spring and the receiving body panel.    I need entire subframe to drop about 1 1/2” further?

( NB : I quit, in frustration ,at this point and bolted everything back together pending advice on this forum)

So…when I get to step (6) next attempt and need more clearance:
(A) can I remove entire spring assembly and provide clearance that way?
OR
(B): I think, if I have engine supported independently ( as I do):
* remove both motor mounts which will disconnect engine from subframe and hopefully allow subframe to drop the required 1 1/2” ( need to support subframe with another engine Jack .  At this point, subframe will be fully disconnected drivers side but still attached by left subframe mount and shock absorber.  Jack under subframe mount DS is to prevent any surprises.

OR
(C): keeping engine supported, remove entire subframe ( must disconnect brakes and a lot of the steering mechanism….a huge job!).   I do have to get at motor mounts to replace as well as part of this job.

HELP PLS……..DOOR # (A); #(B) or (;pls no!) #(C)

BTW: once successfully completed, I promise to document clearly with pictures the entire process.   My Haynes manual is rather vague and can’t seem to find relevant part in BBB.

Bshaunessy

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Re: FRONT SUBFRAME BUSHINGS, MOTOR MOUNTS / replacement
« Reply #1 on: October 02, 2022, 22:58:57 »
Adding back up photos to post above:
(1) car on hoist ( boy I’m glad I have that hoist)
(2) front DS spring with subframe bushing at top
(3) close up of subframe bushing
(4) NEW subframe bushing waiting to be placed into new home….somehow

clunker

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Re: FRONT SUBFRAME BUSHINGS, MOTOR MOUNTS / replacement
« Reply #2 on: September 29, 2024, 13:48:46 »
bumping this thread - did you manage to get the bushing removed? it is unfortunate you not get any response to this - but expect you not the only one who has battled this. (I simply sizing up the project, so not able to add any further insight).
Charles
1969 US 280SL 4-speed Red/Black
DB9 / 981 S / G300 SWB / CB750 / etc

Pinder

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Re: FRONT SUBFRAME BUSHINGS, MOTOR MOUNTS / replacement
« Reply #3 on: September 29, 2024, 15:13:46 »
these can be removed without lowering subframe. I replaced mine with car on jackstands at the front and using a long leaver. possible to just squeeze it out and in. i had posted doing this in this forum.
1970 280 SL Light Ivory DB 670. 4 Speed manual shift no AC Limited Slip Diff.
1997 Corvette C5 Silver. automatic
2015 BMW 320i xdrive
2021 Mercedes GLS450 Silver

clunker

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Re: FRONT SUBFRAME BUSHINGS, MOTOR MOUNTS / replacement
« Reply #4 on: September 29, 2024, 18:33:51 »
Thanks. I did also see the tool Dan Caron proposed, and added that detail to the tech manual.
Charles
1969 US 280SL 4-speed Red/Black
DB9 / 981 S / G300 SWB / CB750 / etc

ja17

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Re: FRONT SUBFRAME BUSHINGS, MOTOR MOUNTS / replacement
« Reply #5 on: October 16, 2024, 16:58:06 »
I usually have to unfasten the two 22mm nuts where the front caster adjustment is located. This allows the subframe to drop a bit more for additional clearance. Be sure to mark everything so you will not alter your camber. A pry bar is still needed to get the clearance to slip the subframe mount in place.
Joe Alexander
Blacklick, Ohio
1969 Dark Olive 280SL
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1982 300TD Wagon turbo 4spd.
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rwmastel

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Rodd

Did you search the forum before asking?
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Bshaunessy

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Re: FRONT SUBFRAME BUSHINGS, MOTOR MOUNTS / replacement
« Reply #7 on: October 16, 2024, 23:00:50 »
Rodd
  Thx for the research.  I had actually reviewed all those posts previously ( and just re-read again), as I "used the search function", as instructed! But thanks for the post nonetheless.
  BTW: I have the new subframe mounts in hand but haven’t attempted install yet.
   I am planning on also replacing the engine mounts as part of same job.  I will be pulling the engine to replace the motor mounts to also do an engine re-seal ( leaking oil in several places) which will make the subframe mount replacement much easier.
  I have just  finished this same job on my 1957 190SL which uses more or less the same engine mount and subframe mount architecture. Doing this job on the 190sl with engine out has convinced me to follow the same procedure on my 280SL.  Also several comments on this forum has convinced me to do ALL rubber bushings at same time ( engine mounts, tranny mount, subframe) as good preventative maintenance.