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Creeking Tower Bolt What Subframe Mount


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#1 phillrulz

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Posted 15 May 2019 - 09:14 PM

Hi guys, got a nasty creek on the SPI, think ive narrowed it down to the towerbolt subframe mount. On dry steering or any steering to be fair, i get a creek from high up passenger footwell. 

 

IF i stick my finger through the grometered hole onto the rack i feel no movement or vibration, u bolts tight as rack isnt moving, lower subframe to toeboard tight, knuckle joint greasy, quite a bit of rubber protruding from between bulkhead and subframe suspension mount, if you put your finger on the towerbolt / rubber spacer / suspension mount can feel the creek. 

 

So going to look at changing the towerbolt subframe mount. 

 

 

So.... million dollar question. 1275 SPI Cooper, what subframe mounts do i go for, rubber, alloy or poly. Car is rarely driven. 

 

 

Also, am i right in saying they can be changed with everything in ( engine brake servo etc)  by just taking the toeboard mounts off and releasing the tower bolts and jacking the car up via the floor pan with a good plank across it, hopefully there should be enough slack to let the subframe drop just to awkwardly get the new mounts in . 

 



#2 RooBoonix

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Posted 15 May 2019 - 09:30 PM

I would say get a full set of solid mounts for the front subframe, so this would be toeboard, tower and front panel tearfrop mounts. Don't mix and match.

 

As to which ones, if I was buying again I would go for DSN Retrosport toeboard and front panel mounts and Minispares tower mounts (Only because DSN don't do tower mounts). I am currently running full Minispares solid mounts and theyre fine, just not a fan of the front panel teardrop mounts as they are cast and mine corroded horribly where the bolt sits. 



#3 nicklouse

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Posted 15 May 2019 - 10:32 PM

i would just replace with the same rubber.



#4 riktanius

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Posted 16 May 2019 - 06:08 AM

Rubber, especially new rubber, on a car that sits, won't last long.

If you go all metal, then the alloy way is smart, but avoid galvanic corrosion.

Personally in would split the difference and use ploy bushings. Some play, but they will last a long time and no worry about rusting or corrosion.

#5 Pete - W.Sussex

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Posted 16 May 2019 - 07:02 AM

Poly on the tower bolts, rubber on the toe board and standard tear drops for me.

#6 cal844

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Posted 16 May 2019 - 07:40 AM

Front Poly mounts should be binned

Edited by cal844, 16 May 2019 - 07:40 AM.


#7 pete l

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Posted 16 May 2019 - 09:26 AM

Front Poly mounts should be binned

 

Would you like to say why ?



#8 dyshipfakta

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Posted 16 May 2019 - 09:50 AM

I have the alloy and polly on the tower bolts seemed like a good compromise to me. So far no issues to report

#9 phillrulz

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Posted 16 May 2019 - 03:46 PM

I would say get a full set of solid mounts for the front subframe, so this would be toeboard, tower and front panel tearfrop mounts. Don't mix and match.

 

As to which ones, if I was buying again I would go for DSN Retrosport toeboard and front panel mounts and Minispares tower mounts (Only because DSN don't do tower mounts). I am currently running full Minispares solid mounts and theyre fine, just not a fan of the front panel teardrop mounts as they are cast and mine corroded horribly where the bolt sits. 

 

 

i would just replace with the same rubber.

 

 

Rubber, especially new rubber, on a car that sits, won't last long.

If you go all metal, then the alloy way is smart, but avoid galvanic corrosion.

Personally in would split the difference and use ploy bushings. Some play, but they will last a long time and no worry about rusting or corrosion.

 

 

Poly on the tower bolts, rubber on the toe board and standard tear drops for me.

 

 

Front Poly mounts should be binned

 

 

I have the alloy and polly on the tower bolts seemed like a good compromise to me. So far no issues to report

 

Thanks all for your contribution 

Right, think im going to go for Metal all round. Was i right in saying all mounts can be changed with engine in just dropping the mounts and letting it sag while jacking the floor pan with a plank across? 



#10 KTS

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Posted 16 May 2019 - 04:10 PM

won't a plank across the floor foul on the exhaust ?

 

you might also want to think about supporting the front and back of the subframe if removing all the mounts simultaneously, and consider whether you need to disconnect the brake line that runs between the bulkhead and subframe.  you want to avoid stretching that when lifting the body off the subframe.  (same applies to the clutch line but the slave can simply be unbolted)



#11 phillrulz

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Posted 16 May 2019 - 04:40 PM

won't a plank across the floor foul on the exhaust ?

 

you might also want to think about supporting the front and back of the subframe if removing all the mounts simultaneously, and consider whether you need to disconnect the brake line that runs between the bulkhead and subframe.  you want to avoid stretching that when lifting the body off the subframe.  (same applies to the clutch line but the slave can simply be unbolted)

 

 

Good shout on the exhaust, didnt think of this, also maybe the gear box rod... Damn it 



#12 unburntfuelinthemorning

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Posted 17 May 2019 - 06:43 AM

...quite a bit of rubber protruding from between bulkhead and subframe suspension mount...

 

So...what subframe mounts do i go for, rubber, alloy or poly?

 

Also, am i right in saying they can be changed with everything in ( engine brake servo etc)  by just taking the toeboard mounts off and releasing the tower bolts and jacking the car up via the floor pan with a good plank across it, hopefully there should be enough slack to let the subframe drop just to awkwardly get the new mounts in . 

I've found on some cars the rubber between the subframe and bulkhead is twisted ninety degrees for whatever reason.  You only need to drop the subframe very slightly to correct this and it may be enough to stop the creeping.  Sometimes the tower bolts are loose too.

 

Changing all the mounts to solid metal is the way I'd go as it's closest to how the early Minis were before BL thought rubber mounting the frame was a good idea.

 

People often suggest reinforcing the front of the floor for the rear frame mounts to prevent cracking; might be worth considering.

 

I'd suggest jacking the car up on the subframe, not the floor, and then with the car in the air when you can see better support it carefully right at the front of the floor where it meets the bulkhead using lengths of wood to spread the load over a wide area.

 

You can either drop the rear as you say or alternatively you may be able to do all on one side at the same time. 

 

The Haynes workshop manual will help make you aware of what to watch out for in the section on replacing the steering rack.

 

Main thing to watch as KTS says is that you don't strain the brake lines.  Watch the fuel lines, exhaust and clutch hose too, and oxygen sensor wiring depending where that is.

 

 

If you go all metal, then the alloy way is smart, but avoid galvanic corrosion.

Good to be aware of.  How do you isolate the two metals?  A layer of paint should be enough shouldn't it?

 

 

won't a plank across the floor foul on the exhaust ?

You can have a short length of wood under each side of the floor, it doesn't have to cross the middle. 



#13 riktanius

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Posted 17 May 2019 - 01:58 PM

 

If you go all metal, then the alloy way is smart, but avoid galvanic corrosion.

Good to be aware of.  How do you isolate the two metals?  A layer of paint should be enough shouldn't it?

 

 

A thick enough layer should be fine. What most people use to protect the underside will work perfectly. 



#14 tiger99

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Posted 17 May 2019 - 09:48 PM

If you mix mount types you WILL get fatigue cracking in the shell, often in the inner wings, but also possible, and much more dangerous as it can't be seen, on the lower face of the bulkhead crossmember.

 

The poly toeboard and teardrop mounts are structurally useless and ought to result in a MOT failure.

 

It really has to be all solid (preferred) or all rubber. If all solid, don't forget that you need strengthening plates, about 2mm thick and 150mm square welded to the toeboard on the inside, because the solid mounts don't attach where the originals did, the floor and toeboard being slightly different. In the early Minis, one bolt went vertically through the floor and the other at an angle through the toeboard so the angle between toeboard and floor stiffened the mounting point. Fitting an originally rubber mounted subframe with solid mounts transfers the load to the mddle of an almost flat sheet, which will flex and crack if not stiffened. Adequate engineering practice would allow stiffening plates to be bolted with about 20 short M6, or even M5 set screws, grade 8.8, around the edge and be structurally sound, but the MOT rules might make it a failure. A seam weld is also structurally sound, invisible from below, and if you have carpets the MOT tester cannot see it at all. You of course need plenty of zinc primer in between plates and toeboard, and seam sealer around the edge, and some suitable sealant around the mount bolts, to prevent corrosion between stiffeners and toeboard

 

As all of this has been explained very many times in the past, often by Cooperman, I am amazed that there are so many wrong answers. I would urge people to search for previous answers before pounding their keyboards with incorrect information or guesswork.



#15 Dusky

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Posted 17 May 2019 - 10:09 PM

Front Poly mounts should be binned


Another genius idea. Next post : why isnt the front lined up properly?

Edited by Dusky, 17 May 2019 - 10:10 PM.





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