Author Topic: Changing out Mini front subframe mounts with the engine in the car  (Read 586 times)

Offline BruceK

Seems most people install new subframe mounts when rebuilding car its a breeze with an empty subframe.  I'm posting this because I searched the Interwebs and could not find anything on how to install new subframe mounts to a Mini with the engine still in the car (i.e. a fully road-worthy Mini).   I have a 1988 Mini, but this should be the same for any post-1976 Mini with the rubber-mounted front subframe. 

Since I would be lifting the Mini's body slightly off of the front subframe in order to gain access to install new tower mounts as well as new rear mounts at the toeboards, I first considered whether I would need to disconnect some of these items that are hard linked between the subframe/engine to the car body itself:

- Front shocks
- Hard brake and clutch lines up against the firewall
- Hard brake lines running from the back of the subframe to the rear brakes
- Fuel line running up from body to carb
- Engine steady bar running to the firewall

In the end, I chose not to touch any of those items - I just left them alone.  From what I could determine, the car body only needed to be lifted at most an inch, and probably less to gain enough space to change out the tower mounts and the rear toeboard mounts.   I reasoned that on my car there was enough curve or bend in the hard hydraulic lines to allow some minimal flex.   Likewise, I reasoned the shocks should allow a little extra extension, and the engine steady bar would just pivot slightly upward.

So here are the steps I followed with the car sitting on its tires on the ground:

1) Disconnect the battery since the cable runs right next to rear toeboard mount and links the body to the subframe - don't want that to possibly get pinched as the subframe is moving around

2) Undo the big tower bolts using a 1 5/16" socket (same as for the front hubs on the disk brake cars) and remove the bolts

3) Undo the 4 bolts that hold the subframe tails to the toeboard mounts (1/2") and remove them

4) Loosen the bolts going through the front teardrop mounts  (I chose to keep the loosened bolts in place here as I wanted to keep some general alignment link between the body and subframe and I recently changed out the front teardrops so they are still new on my car)

5) Using two 1X3 or similar sized pieces of wood to spread the loads, position a floor jack at the toeboards on each side of the car.  The wood goes under the welded seam right where the slanted toeboards meet the horizontal floorboards across the body - make sure not to pinch any break or fuel lines

6) Gently jack each side of the car body up just a half inch or so - try to coordinate jacking on each side - you should begin to see the body lift off the rear subframe mounts.

7) In the engine compartment you should now see a gap increasing between the top of the subframe towers and the body.  You should be able to pull out the old rubber compressed subframe mount fitting a new mount (rubber, poly, or solid) will likely mean having to raise the body just a little bit more, so, before lifting the body any more, take stock of the potential stress points (all the subframe to body connection issues I mentioned at the start) and make sure you are okay with them

8 )  The lower tower mount needs to slide over the raised stub of the top of the subframe tower and sit around it.  There was enough room to fit the top mount with the body lifted probably 3/4 to 1 inch off the subframe.

9) Fit the new upper mount into the hole in the top of the body and slide the bolt down into the hole to help maintain body to subframe alignment and keep the lower mount from possibly falling off its perch

10) Back underneath the car, loosen and remove the 1/2 nuts holding the subframe mounts to the toeboard note that the bolts are semi-moveable as they are linked together by a metal strap under the carpet inside the car.   So it is possible to push the threaded bolts up a little bit to help get them out of the way to remove the old mount. Remove the old mounts and fit the new mounts but leave them loose enough to allow some flexibility when trying to get the subframe bolts aligned (On my car, the subframe to mount bolts were fine-threaded, while the subframe mount to car body were coarse that created a little confusion trying to thread on nuts until that was noticed)

11) Lower the jacks and line up the lower subframe mounts to the subframe. This is the fiddly part - had to poke a screwdriver into the subframe and catch the subframe mount and wiggle it around in order to get it aligned before the bolts would drop in (much like playing with engine mounts).  Also had to adjust the jacks to vary the height of the body side to side slightly before things lined up.   

12) Let the body down fully on the subframe and tighten everything back up.  Supposedly the big tower bolts should be tightened to 50 ft lbs.    That might be great with a solid mount, but I think that is overkill for a rubber or poly mount.  I tightened up the big bolts snug, and then tightened just a little more.  Ill monitor it and make sure it doesnt loosen once Ive driven the car a little. 

Disclaimer:  You are an adult, so consider for yourself the risks of working on a car and that of trusting information like this found the Internet. 


(Finally, thanks to Mark for helping me install these mounts on my car!)


« Last Edit: February 20, 2017, 10:09:40 PM by BruceK »
1988 Austin Mini
2002 MINI Cooper S
2007 Triumph Bonneville

Offline MiniDave

Re: Changing out Mini front subframe mounts with the engine in the car
« Reply #1 on: February 20, 2017, 03:13:47 PM »
I'm glad you go that job done, were you able to notice any difference in NVH or the way the body lines up to the front mounts? IE will you be able to get your tow bar installed without having to jack the body around?
1989 Cooper Racing Green
2009 Clubman S
1969 Jaguar XK-E FHC
2004 Audi Allroad 2.7 TT

Offline BruceK

Re: Changing out Mini front subframe mounts with the engine in the car
« Reply #2 on: February 20, 2017, 04:01:24 PM »
Haven't driven it yet - I'm hoping the front subframe holes will line up better now making it easier to install and remove the towbar.   

I used poly mounts for the towers, and stock rubber mounts at the front and back.   The only reason I chose poly was because they should be more durable that rubber.  If you remember, my rubber tower mounts started failing and were squeaky as hell.   I applied lithium grease to the poly pieces to help keep them quiet.
1988 Austin Mini
2002 MINI Cooper S
2007 Triumph Bonneville

Offline gr8kornholio

Re: Changing out Mini front subframe mounts with the engine in the car
« Reply #3 on: February 20, 2017, 07:23:34 PM »
Glad I could help, was a great learning experience.  Also gave me a lot more confidence to tear into my own car.  Learned a lot the day before also doing the hubs and bearings. 

One proof reading note for your write up, which is excellent!  In line 6 you use subframe twice where I think the first should be body.

6) Gently jack each side of the car body up just a half inch or so - try to coordinate jacking on each side - you should begin to see the subframe lift off the rear subframe mounts.

Only other note, holding onto and positioning greased up poly bushings can be a slippery business so go slow and let them slide into place.
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Saussie Aussie 1965 Australian MK1 Mini.
"Beavis" - 07 MY/MY MCS, B/MY Konig Daylites, JCW sideskirts, TSW springs, TSW lower rear control arms -- Exploring the country with new friends since 11/09.

Offline John Gervais

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Re: Changing out Mini front subframe mounts with the engine in the car
« Reply #4 on: February 20, 2017, 07:34:30 PM »
When I did mine, I lifted the car in the usual way, supported the bodyshell using jackstands (protected with thick rubber blocks) at the toe-board corners, re-positioned the jack under the front subframe legs and lowered the subframe from the body.

- Pave the Bay -

Offline BruceK

Re: Changing out Mini front subframe mounts with the engine in the car
« Reply #5 on: February 20, 2017, 10:09:08 PM »

One proof reading note for your write up, which is excellent!  In line 6 you use subframe twice where I think the first should be body.

6) Gently jack each side of the car body up just a half inch or so - try to coordinate jacking on each side - you should begin to see the subframe lift off the rear subframe mounts.

Yup, I will fix that. Thanks for the catch.



Only other note, holding onto and positioning greased up poly bushings can be a slippery business so go slow and let them slide into place.

When greased, they sure are slippery!
1988 Austin Mini
2002 MINI Cooper S
2007 Triumph Bonneville