I've been trying to figure out what's causing this for about two hours now (I decided to just continue the investigation tomorrow in the morning).

But when I am up to speed and let off the gas pedal quickly I hear (and slightly feel) a clunk coming from the rear. At first I thought it could have been the exhaust pipe, but it's not loose at all.

I do have a manual transmission, not sure if it has anything to do with that though.

I wanted to see if anyone else had this problem or something of the like so I could fix this tomorrow.

 

battery or spare loose in the boot? maybe even the gas tank has worked loose? if none of those you probably need to look at the suspension . . .

 

I was thinking it might have been the suspension, but maybe it is those others. I'm about to have some breakfast and head out in the garage. I'll keep you posted!

(I honestly think there is a gnome in the boot with a hammer making this noise just to mess with me)

 

I had something similar when the bolt in the boot, on the top of the shock worked loose. It allowed the shock to bounce a bit - there's also a rubber bushing there which can wear out. ususlly one side is easy to see, and the other hides behind the fuel tank . . .

 

With my luck, it will be behind the fuel tank


I just took it out for a quick drive in the neighbor hood. When I am upshifting and accelerating on a level or decline road then the bang can be heard. But, once I try that going up a hill, no bang. I'm telling you it's a freaking gnome back there!

Going to go back out and jack up the rear to try and figure this out.

 

I believe in the gnome possiblility as well!! I could be sitting in my car, engine off, radio off. If I shake back n forth in the seat, there's a slight clunk in the back. He's messin with me too dammit!

 

Both my exhaust pipe brackets snapped... so this may be the culprit (I hope).

 

very likely

 

I replaced both brackets with new hardware and the bang is gone!

I'll tell ya the last bracket with the rubber is one shitty design, I got a piece around the same size, drilled a hole through it and then put a bolt through the bracket, frame, and rubber. That thing isn't going anywhere now.

 

now the question is did they break just from age

or is the engine moving too much. Time to take a look at the engine mounts and the bushings in the upper steady bar.

 

The one bracket was broken from the other owner, thin piece of metal and it snapped in half. The rubber rotted out. But I will look at the those as well.

 

You know Capt, you're going to need to start charging people for help ;D

Now the bushings and engine mounts seem more likely. When I press in the gas pedal quick the engine moves and makes a clang sound and the same when I quickly release the gas pedal. But, this only happens when I am in gear not in neutral.

 

OK

when you rev the engine in neutral it responds to the properties of physics about spinning things and induced forces .... the engine tries to twist away from the increased/decreased forces of the moving parts. Usually this isn't much force. so you just see a little motor movement from torque.

When you do this in gear tho you take up the slack in the drivetrain, as the axles try to move they introduce back pressure thru the tranny to the block and it tries to twist away from the force .. tries to leave the axles standing still and move the motor

Your clang is a result of this force hitting an unmovable object. What are the possible sources?

It could be slack in the axle joints which means things are sloppy and there can be movement in the axle joints when they should be tight - I know I have a bit of this happening.

It could be worn motor mounts (incl the steady bar) allowing the motor to move around and this one DOES translate to flex on the exhaust system!!!!

How to troubleshoot .... well, I'd get a helper and CAREFULLY be looking listening under the bonnet as the car was put in and out of gear - ensuring no one got run over!!!!! watch for movement of the block as you engage.

I'm not smart about this stuff, I'm just about 5 years ahead of you on the time line. I had these questions 5 years ago when I first joined Mini'dom. I ended up having to figure out many of these issues myself or at a cost $$. But always take my help with a grain of salt.

My listening to an unknow expert cost me a couple of hundred $$ and about 2 months time when they mis-identified both my block and dizzy model and I failed to double check . . . Pertronix upgrades are easy IF you buy the right parts. The wrong parts can actually fit - they just don't work right.

 

Very true, even if someone knows what they are talking about, it's so hard to really help trouble shoot without actually seeing it in person (even then it can be hard too!)

No doubt one of the problems is the upper steady bar. Below are pictures of the bushings. The smaller is of the front section that connects to the engine, but if you look at the larger one it's of the rear bushing.




I still have to check the motor mounts but I'll see if I can find anything else.


Edit: The bottom park of the bracket that the steady bar bolts into that attaches to the firewall snapped. So I'm going to have to figure out a way to retrofit that and fix it. Just ordered new engine mounts and steady bar bushings though.

 

there's a smoking gun for sure!

It also is telling you to question the condition of every other rubber bushing in the car. Start with the big bushings at the front subframe mounting points. If they are in similar condition you have something new to get on your list.

I was very fortunate that just b4 I bought my Mini every such bushing had been replaced with poly. I see nice red poly rather than rubber in all those locations.

trying to find a part number for that plate ... but not having any success. It would be pretty straight forward to weld a new end on that plate, but I'd wonder how stong is what's left . . .

 

Even if a weld would work, it doesn't look too easy to weld since it's such a tight spot. I was thinking of bending a thicker gauge metal into an L shape then bolting it to the firewall. The factory metal on that spot isn't very thick so no wonder it snapped. I came across this http://www.7ent.com/products/dogbone...nt-for075.html

I'll just fabricate a new bracket, it's a simple enough bracket so why bother paying someone else to do the work in making one for you

Thank you a lot for all your help, I'm learning a lot from this.

I'm going to put this fix on the back burner until I get my new parts, but onto others!

 

most of your add-on steadies just bolt to the firewall so that's certainly a decent way to go. There isn't a lot of force here, but it is in an important place as too much flex causes problems. I was gonna say "I'd just make one" but not everyone has metal fabrication tools in their garage.... ditto the weld it comment.

What's really cool is that once again Seven seems to have the unique part to solve a problem. They've filled such a gap for me more than once.

 

Going to have a friend come over tomorrow morning with a 90 degree angle drill, seems like that is one of the few drills that could fit in the 3"-4" clearance.

Bushings and engine mounts will be delivered on Wednesday. It will be good to start fresh with these things for the time being. More bushings will come in the near future.

 

i used poly bushings and i also added an additional engine steady on on the bottom and top of the motor. (4 steadys in total - 2 top & 2 bottom)
issue solved!

 

Well heck, your engine isn't going anywhere now!

I'm in the process of replacing the engine mounts, just taking my time and being patient. I managed to the get the old one out from under the clutch without having to remove all 9 bolts and the whole clutch/flywheel housing. Oddly enough...the mount didn't look worn at all. But, the mounts that I ordered from MOSS so far does not align properly with the holes for the bolts, it's about 2mm off so I think I will need to file the lower hole to give it that extra 2mm it needs to line up.

Still have to tackle the radiator side so hopefully that goes fine as well.

 

I don't envy you. That can be a pretty frustrating job.

Jeff

 

a lil' easier if you can easily put your car in maintenance mode



front clip comes off in about 5 minutes . . .

 

Lmao! I must say, a Mini looks a lot larger without the front body on it!

Just finished getting the new mount in, without having to take off the clutch/flywheel cover (even though the Haynes manual said I had to do so)!!

Time for some lunch and then I'm going to do the other side mount, there is a lot less steps in the Haynes manual so I am hoping it won't be as hard.

 

Upper steady bar bushings and engine mounts replaced, top part of the engine is a lot sturdier and the engine doesn't vibrate as much. Still have the clunk though... it's not as temperamental as before but it's still there.