New Noise - Part 2 another new noise

Pete · Post by **Pete** » Mon Jul 20, 15 12:43 pm

I did one up to 75ft lbs WITH loctite on the race car and one bolt came loose 3rd run......new plate, new convertor, who knows???

They MUST be done up FT...

Post by **MattH** » Mon Jul 20, 15 12:53 pm

What concerns me is the book torque figure is quite low, about 35ftlb or similar.

Pete · Post by **Pete** » Mon Jul 20, 15 12:57 pm

I was using the 3/4" headed bolts!

MilesnMiles · Post by **MilesnMiles** » Mon Jul 20, 15 1:25 pm

Sounds very unlucky Matt/Pete. I just use locatite and factory torque and never a problem. Matt, is it the correct plate? I ask as on my 360 I used the TCT plate for external balance and it has a cut away section as opposed to being symmetrical. Is that what you are using?
Matt, are you sure you have the correct flex plate?
The one you have is for an internally balanced motor like the early 340.
If you have an external balance motor you need this one
http://www.bmracing.com/products/10231- ... ced-crank/

Used a similar TCI one on my 360 motor.

MilesnMiles · Post by **MilesnMiles** » Mon Jul 20, 15 1:27 pm

Also, Matt. I have had success in moving stubborn sheared bolts by using a centre punch at an angle.
That said, why has it sheared anyway? Must be some lateral movement?

Dave999 · Post by **Dave999** » Mon Jul 20, 15 2:10 pm

sheared because it was under shear stress

the junction between the two THINGYS is supposed to carry the force by friction between the 2 surfaces. not the shaft of the bolt.
(unless bolt is push fit like a dowel and is shanked fatter than the thread section)

for this to work

1) no rust dust or bits. surfaces need to be clean to micro weld otherwise they chafe back and forth.
2) no thread lock between the surfaces only on the thread 2 much and it squishes out of the hole and pushes the 2 clamped-toghether things apart reducing the friction between the 2
3) head of bolt needs to see a nice flat surface

original bolts for flywheel to crank had recessed heads??

was that the case for original flex plate to converter bolts??

JUST CHECKED and they do SEE HERE

http://www.ebay.co.uk/itm/OEM-Mopar-Fle ... 4aed4942e0

nice wide heads, back cut to the shaft if you squint at the picture

i.e the flat of the head that clamps down, was back cut away from the main bolt shaft leaving only the outer 1/2 circumferance of the head of the bolt

thus you had a decent sized bolt you could torque to X but the friction between the head and the surface it bolted down onto was double or more what you would get with a totally flat headed bolt, due to it all being concentrated into the rim of the bolt head not spread across the whole face. Pressure=force divided by area.
The smaller the area the higher the pressure and = more friction between bolt head and what it rested on.

totally flat headed bolts at same torque will therefore need assistance

same princepal used on flywheels with a cosworth ring.

Dave

Post by **MattH** » Mon Jul 20, 15 6:45 pm

Miles, that is the flex plate I have, sourced it from Hauser's and then had the starter fouling issue but that is sorted with a mini starter.
I was thinking the punch method might get the sheared bit off.

Clearly I have had some movement with the bolts working loose so will have to check properly on reassembly and buy some fresh Loctite.

MilesnMiles · Post by **MilesnMiles** » Mon Jul 20, 15 7:38 pm

Matt, so your engine is internally balanced?

Meantime, I found this that might be of some use

A couple of more points to remember. The OEM converters were mounted the flexplates with 5/16 bolts with thin heads (thick heads can catch on the block webbing). Most aftermarket converts are drilled for 3/8 or 7/16 mounting bolts. do not onder any circumstances use a flex plate that is drilled for the larger bolts with the 5/16 mounting on a converter. Also the flex plate cannot be mounted to the engine or the converter wrong or back wards. 1 hole is offset at each place so will only mount in one position. Do not modify to fit. Trial and error and you will find the right spot. Best to locat on the converter on the floor and mark with a shot of paint.

Post by **MattH** » Mon Jul 20, 15 9:09 pm

Hmm that's a worry, have I got small bolts in bigger holes on the flex plate?
It is the original converter and bolts but the SFI plate.

Post by **MattH** » Thu Jul 23, 15 12:22 am

Got it sorted for now, as per the other thread.

One good thing that came out of pulling the gearbox out is that I discovered I have the matching numbers transmission!!!

morgan · Post by **morgan** » Fri Jul 31, 15 10:00 am

Had a good chat with Matt at Harpenden. this thread has been in my mind since. I've got the tictictic noise.

Had it ages, assumed it to be the header gasket as usual. Been through that pain now, tried the crushable aluminium ones. Tick still there. Might even be louder.

Cant hear it while driving. Only on idle when next to a wall or hedge or something (i.e. the noise bounces back at me). tictictictic...

3 things likely I guess.
a) The gasket hasnt worked (fairly likely)
b) I have a loose flex bolt (quite possible. My gearbox is fairly brutal sometimes)
c) Minimal (like a few mm) gap between exhaust and torsion bars. Might be tapping each other ?

It sounds (from the outside) down low.
Anyway - following chat with Matt I am going to have a crawl underneath her and check the ol' flex plate bolts I reckon...

Dave999 · Post by **Dave999** » Fri Jul 31, 15 1:31 pm

what you need is crushable graphite ones

sureseal gasket

Dave

Pete · Post by **Pete** » Fri Jul 31, 15 1:39 pm

Morgan - if you are running tubular headers then I don't think you have a problem.

They are much noisier than OEM Cast Iron ones, I find I get noise reflected back from objects such as walls and even lorries in the Super Bee...

..it is a bit unsettling but actually nothing wrong....

morgan · Post by **morgan** » Fri Jul 31, 15 1:56 pm

Dave - Thats the only type I DONT have in my selection. I am working my way through. If these ones are truly rubbish I will try the copper ones next. Next order though, I'll stock up on graphites too

Pete - TTIs. The usual tappety noise - but all looks lubed and lovely under the rockers so I assumed the a,b,c below... Didnt know they tend to do it anyway.

MilesnMiles · Post by **MilesnMiles** » Fri Jul 31, 15 6:25 pm

I'm with Pete, reversing down my drive with only 2" to spare either side sounds like hell is breaking loose on a cold motor. Once on the road it's all good. That said, I do have that tappety thing going on too Morgan; going with adjustable rockers shortly.