Which clutch!?

[Disco]

Hello all, it's been a while.
I need help figuring out which clutch and flywheel I need for my truck. I don't have it out, and I don't want to play the return/exchange game. I'm letting a shop do the clutch job because I've only ever done a clutch once, it was nearly 20 years ago, it was on an old VW Bug, and I wasn't alone. I'm not brave enough to try this by myself on my back under the truck with no help or even anyone to call 911...

My goal is to order the parts to save a little money at the shop -- they quoted $400 in parts.
AutoZone and O'Reilly both have a few size options.

My 78 Big 10 has a Muncie SM465 mated to a 350.

Thanks!

 

[SquareRoot]

Your truck is pretty standard equipment. An 11 or 12 inch clutch will work. Please buy a "clutch kit" so that you get the correct associated hardware, specifically the correct throwout bearing. And don't forget to replace the pilot bearing/bushing while your in there. SB's are standard size, .590.

Confirm that you have a 153 or 168 tooth flywheel before you order anything. Look at the starter bolt mounting configuration. If the two bolts are straight across from each other it has the small flywheel. If the bolts are angled it has the big flywheel. I'll bet $$$ it's the 168 since it's a manual trans.

 

[Disco]

Ok, so the clutch is either/or? I assume the 168 tooth flywheel is larger in diameter than the 153. So wouldn’t I want the larger clutch in that case?

 

[Disco]

This is my first vintage American vehicle, if you can’t tell. I’m pretty clueless.

 

[Grit dog]

Depending what you plan on putting in front of the clutch for HP, may consider skipping the Vato Zone stuff and getting a quality heavy duty clutch like a Hayes Brute.
Compare prices at least. This is one of those only wanna do it once “forever” type of repairs or upgrades. Especially if paying the labor to do it.
Also check with the shop first. Many/a lot of shops have no interest in installing customer supplied parts. Both for financial and/or warranty reasons. Other shops don’t care.
I had a clutch done years ago by a shop due to circumstances (in the process of moving and tools were already packed and shipped…) and they were fine with me supplying. However I was moving 2500 miles away so they would never deal with warranty. And I wanted a specific heavy duty clutch for a diesel.

Understand your reluctance somewhat. However a little gear box like that and 2wd is easy and safe even with just a food jack. Slam dunk with a rental trans jack. Just throwing it out there.

 

[SquareRoot]

Ok, so the clutch is either/or? I assume the 168 tooth flywheel is larger in diameter than the 153. So wouldn’t I want the larger clutch in that case?

Not really. I have a 168 and an 11 inch clutch. An 11 inch is more than enough for 90% of daily drivers. Some 12 inchers may interfere with the inside of the bellhousing. A 12 inch will not fit inside my bellhousing. I only have about an 1/8th clearance in some places. It's not just the diameter, it's also the shape/depth that can cause issues. Also, most larger clutches mean more effort to disengage. That quickly becomes a PITA in stop and go traffic. This is a good example of keeping the "Bigger is better" approach in the bedroom.

 

[Rickf]

Avoid a three finger pressure plate like the plague.

 

[Turbo4whl]

Also check with the shop first. Many/a lot of shops have no interest in installing customer supplied parts. Both for financial and/or warranty reasons. Other shops don’t care.

To explain this reason, these same shops will offer a warranty. Yes they mark up the wholesale price of the parts to retail or list price. This extra money allows them to redo a job when a part fails. So the small markup on many jobs makes a fund to pay the labor on failed jobs.

With all the imported parts, there are failures. A shop might install your parts, but they will tell you no warranty for that job. They also learn which cheaper parts not to use on your vehicle. (did I say Airtex fuel pump)

 

[Disco]

Ok. So, from what I'm gathering from all this info, if I'm not willing to do the job (in this case, anyway), I should let the shop do what they need to and just deal with the associated markup on O'Reilly parts.
This shop does allow owner-purchased parts. They just don't warranty them and it's a "use at your own risk" thing because they won't hold themselves responsible if the part gets broken or ruined during the repair. It makes me a little nervous about having them install these expensive coated stainless brake lines, but I'm never going to get them done myself. Not with school in the way...
I wish I had the time (and local friends) to work on the truck myself... But I don't, and I need the truck asap, so to the shop it goes.

 

[Disco]

Depending what you plan on putting in front of the clutch for HP, may consider skipping the Vato Zone stuff and getting a quality heavy duty clutch like a Hayes Brute.
Compare prices at least. This is one of those only wanna do it once “forever” type of repairs or upgrades. Especially if paying the labor to do it.
Also check with the shop first. Many/a lot of shops have no interest in installing customer supplied parts. Both for financial and/or warranty reasons. Other shops don’t care.
I had a clutch done years ago by a shop due to circumstances (in the process of moving and tools were already packed and shipped…) and they were fine with me supplying. However I was moving 2500 miles away so they would never deal with warranty. And I wanted a specific heavy duty clutch for a diesel.

Understand your reluctance somewhat. However a little gear box like that and 2wd is easy and safe even with just a food jack. Slam dunk with a rental trans jack. Just throwing it out there.

I'm not putting anything in front of it. It has something like 75k original miles on it, and the engine runs great, aside from the old, blown Qjet accelerator pump (I have a brand-new Holley 4175 Qjet replacement for it), so it will have the factory 4-bolt main 350 in it until that engine dies. After that, I don't know... I might rebuild the OE engine, I might do a carbureted LS swap. I'll burn that bridge once I cross it.

 

[SquareRoot]

aside from the old, blown Qjet accelerator pump (I have a brand-new Holley 4175 Qjet replacement for it)

@Paladin ....

 

[Disco]

@Paladin ....

???

 

[pduffyd]

Hi Disco.
One thing to make sure of before buying your clutch and deciding between the 11" or 12" version, check your bellhousing. Easy to do to know what you can or cant do.

You must be registered for see images attach

This is for the 11" clutch, note there is no big bulge on the bottom of the bellhouse, just nice smooth casting lines. If you try to use a 12" clutch with this it will hit the casing inside when the engine is running.

You must be registered for see images attach

This bellhouse as seen on my sm465 has the big bulge on the bottom of the casting, so it has room for a 12" clutch, in this case you can also use the smaller 11" if you want. Can use either a 153 or 168 tooth flywheel.

Hope this helps so you know what you have on your sm465.

 

[plumtruckerd]

I order from rock auto and have never been disappointed. Well except their shipping prices have gotten out of line on some items recently.

 

[Craig Nedrow]

Wish I was closer, could give you a hand, that is easy to do, if everything is new.