frozen bolts on VP 280 gearbox

[PiratePast40]

Can't get the capscrews that hold the clamp ring to the gearbox housing loose. Ended up stripping out the interior allen heads on 2 of the bolts but finally managed to get one loose with a 2 foot cheater bar. The allen wrench is the correct size and snug in the socket (or WAS on the two of them).

Is there some secret to getting these out how the heck do I get the two bolts out with the rounded out allen heads?

Here's the diagram:
http://www.volvopentastore.com/UPPER_GEAR_UNIT_AQ_DRIVE_UNIT_280_280T/dm/*******.766014243--qty_329550.4--**********.259546091--store_id.366--view_id.317461--viewcart.long
/gasoline/AQ/130/outboard drive unit/upper gear unit AQ drive unit 280,280T. The capscrew is number 36 attaching the clamp ring to the gearbox housing.

 

[fuzzybob]

Re: frozen bolts on VP 280 gearbox

Get a left handed drill bit and start drilling. Sometimes the heat and the left twist will back out a broken bolt or stud... if not you'll have a place to put your easy-out. Good luck it's a PITA

 

[PiratePast40]

Re: frozen bolts on VP 280 gearbox

Get a left handed drill bit and start drilling. Sometimes the heat and the left twist will back out a broken bolt or stud... if not you'll have a place to put your easy-out. Good luck it's a PITA

Ouch - doesn't sound like there is any magic bullet available. I'll pull the u-joints and yokes to get better access. Is this a relatively common occurrence (no - not some nimrod screwing up the cap screw heads - the bolts seizing so bad)?

 

[PiratePast40]

Re: frozen bolts on VP 280 gearbox

Decided to take the gearbox to a machine shop before I make things worse. They've got 2 bolts out, one that broke off in the housing, and one that won't budge. They'll mill the head off the last one and then pull the clamping ring to remove what's left. The machinist says these are pretty corroded inside the housing.

When I asked what can be done to prevent this, the machinist said that there should be tons of anti-seize on any fasteners with dissimilar metal. So glad I took it to someone with the proper tools and skills.

 

[PiratePast40]

Re: frozen bolts on VP 280 gearbox

Thought I would give an update so others might profit from the experience.

The machine shop had to open the gearcase to remove the broken bolts. They also removed the gearset and shift mechanism. I was reassembling everything and noticed that the capscrew shoulders may have been compromised. I was also uncomfortable with the number of shims since I wasn't the one that did the disassembly.

I also wasn't comfortable with checking rolling torque. As a result, I found a Volvo tech about an hours drive north and will be doing an exchange for a sealed and rebuilt gearbox exchange for $450. He'll install my newer shaft and yoke assembly with the new U-joints. I'll take the intermediate unit also and he'll measure and shim for that as well.

So - that was my experience at trying to change out the yokes and ujoints and reseal the gearbox. I think that the lesson here is that you can probably do the job yourself unless you run into any problems - then it's time to call in the experts to do it right.