fivebolt bellhousing identification

[Dan Case]

Be wary of any used safety bell housing (a.k.a. scatter shield) made by anybody in any design that has already contained a failure. You can tell if high speed heavy sharp objects have been bashing around inside. Example: The cast steel Cobra model for five bolt engines will often be distorted in one to several directions after a big component failure inside of them. Just because bits and pieces don't come flying out in an event doesn’t mean the unit didn’t get stretched one way or several.

I have personally not had any issues with original COBRA five bolt housings that have never had to contain a clutch/pressure plate/flywheel/transmission input failure. They have fit and aligned great with no need to shimming or adjusting position in any way. On the other hand, I have gotten ones that got “well used” after something inside failed and started a chain of failures and it was sort of stretched to one side a little to over an eighth inch. Example: In 2015 I had my local automotive street and race engine shop measure one with very obvious scars on its inside and it was quite distorted and in the end not usable; wall art.

[peterpjb]

this warning seems comprehensible to me in the first place,

but... I am involved in vintage and race cars for about 30 years especially alfa romeo and have never heard about such an issue before,
e.g. the giulietta SZ or TZ has also aluminum body and propshaft tunnel, with engine, belthouse and trans also out of alu, they are reving in the races up to 8.000 and 9.000, never heard about any failure of flywheel or clutch that caused damages, and many many of the other 50th and 60th racecars are driven with aluminum bellhouses, the majority even has no alternative between alu or steel

the only fear according to drivetrain-damages I know is about a detached propshaft, but that can be solved with a propshaft-cage

are there any documented destructions of an aluminum bellhouse and injured legs caused by a flywheel- or clutch- failure?

[Dan Case]

Originally Posted by peterpjb

this warning seems comprehensible to me in the first place, ….
are there any documented destructions of an aluminum bellhouse and injured legs caused by a flywheel- or clutch- failure?

CSX2014 raced by Shelby's works damaged the driver (right foot) and the car crashed. Perhaps that early works failure prompted the development of the COBRA lettered safety models? There have been some street cars with failures in published stories but I won't go digging for chassis numbers. If the owners of those cars want the world to know bad things in their cars’ pasts I let them be the ones to publish it fresh. One “street” Cobra was severely damaged and over the years since 1999 both original halves of the chassis have been offered for sale in ebay® auctions. I had the bonnet from that car hanging on the wall as art for a couple of decades.


Failures happened. Roughly two out of five used COBRA five bolt units I have come across since 1983 as loose parts had very clear signs that something bad happened inside. Not every failure is catastrophic but some are. A seriously modified engine might over rev seriously if a shift is missed while playing or racing. In 2006 we went and looked at a HP289 engine that literally broke in half when the man drag racing a Mustang since he bought it new missed a shift. I had never seen a 289 engine block laying in two broken puzzle piece halves before so that was an interesting visit. Even if not “raced” a missed shift without a rev limiting electronic controller can be trouble to disaster. We have no idea under what conditions and with what equipment all the damaged ones “happened”. There are countless inappropriate things people can do to and with parts.


It is about acceptable risk. Safety equipment in vehicles wouldn’t be necessary if unintended bad situations didn’t come up. Original Cobras are in no way safe car designs. Good maintenance, top quality parts, defensive driving like you were riding a motorcycle, good tires, drive shaft safety loop, and a steel safety bell housing improve the odds ever so slightly in user favor.

[xb-60]

Originally Posted by peterpjb

....I am involved in vintage and race cars for about 30 years especially alfa romeo and have never heard about such an issue before...

Peter - I have an Alfa with a 1779cc engine. It's a road car, but its ability to rev to the moon always amazes me (and its original clutch and flywheel are now 41 years old). Just maybe....those Alfa engines and transmissions were so well designed - and balanced - in the first place, and then even more so for the endurance racing that the TZ excelled in, that failures were uncommon.
If you consider the length of a Cobra's footboxes, it's easy to see how vulnerable the driver's legs are if a bell housing doesn't contain a shattered clutch of flywheel

Cheers,
Glen