Posted April 27th, 2010 at 5:56PMI’ve complained previously about the hydraulic upper motor mounts found on 2004-2006 MINIs. They fail pretty quickly, leaking oil over the passenger-side frame rail, allowing the motor to buck around. Consequently you get worse shifting, additional stress on associated attachments, and more drama all around in demanding driving situations. But it’s one of those maintenance items that creeps up slowly, as the fluid leaks out fully and you fail to notice the gradual deterioration.
I remember mine started leaking early – probably in the 40,000 mile range – before the warranty was up, but I did not bring it to Keeler because I knew they’d try to pin its failure on the aftermarket dampener I had thrown on previously (they’d been fashionable, providing another attachment between sub-frame and engine, and functioning to pep up throttle response and shifting feel – proof of the slop in the stock arrangement even when new). It’s hard to rationalize how decreased movement would cause premature mount failure (and empirically they’re failing early on bone-stock vehicles as well) but I’d gotten that type of response before when bringing the car in for issues.
Last week I got the chance to change out the upper mount, and it’s been a wonderful step back toward the tight, new, snappy feeling of the car when it first puttered out of Keeler’s bays four years ago. Well, almost.
I went with a replacement from Texas Speedwerks, who I’ve dealt with previously and felt confident in getting a quality product from. The TSW mount is urethane, similar to what the 2002-2003 cars had (I haven’t peered at an 02-03 to see how similar / dissimilar they really are, but I know the TSW design is new from the ground up).
I’ve always thought the MINI’s gearbox and shifting feel are pretty spot on perfect, but the increased engine movement due to the failed mount necessitated longer shifts, lest I ground the gear while engaging. Hard launches had similarly been affected, with more wheel hop and dreadful clunky noises.
The installation of the upper mount is fairly straightforward – I split it into two days with requisite beer breaks, and replaced the belt tensioner at the same time since the engine was getting jacked upward a smidge already.
The TSW mount has gotten the shifting back to near perfection (what more could you ask for, a little less throw? hmmm…) and civilized the car when its ordered to a rapid pace from rest. In fact, on both counts, it’s markedly improved from stock. There’s no need for an accessory dampener now and everything is as tight as I feel it needs to be.
(The belt tensioner was perhaps a premature repair – my stethoscope still picks up terrible noise when trained on the tensioner: I believe this is due to the wobbly crank pulley in close (almost touching, flip side of belt) proximity. It’s not at an urgent level, but this is high on my to-do list. Still, the old tensioner did have some slop in the pulley and damper, and deserved to be replaced at some point.)
So crisper shifting and accelerating, what’s the catch? I tried to cheap out and not replace the lower mount, that’s what. Only upon completing my repairs last week did I finally notice cracks in the rubber bushing of the lower mount, which takes the brunt of it after the upper fails. So I’ve got a noticeable increase in off idle vibration, which happens to everyone who replaces the upper mount and leaves the lower in its shoddy state. It’s not terrible, but I went ahead and ordered the whole mount online for half the price Keeler quoted me for just the bushing. It ought to mitigate most if not all of the additional vibration. I decided to stick with the OE rubber bushing here since I’m not making the jump to stiffer polyurethane bushings anywhere else, with their maintenance requirement and increased NVH.
The lower mount arrived today but it’s raining and temps are in the 40s, so I’ll bolt ‘er in once it warms. It’s just two bolts so it’ll take some ramps, a jack, and fifteen minutes. The ultimate verdict on acceptable or not increase in vibration from the TSW mount will then be in and reported.
Edit 5/3/10: After replacing the lower mount… there’s still a tiny bit of new vibration, but I’m not sure I’d say its <em>increased</em> over stock – more like its a different frequency. I’ve got some slight new rattles as a result coming from the dash, the kind where you push on some of the cheap plastic and it goes away. *shrug* It’s an acceptable trade-off for me.
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