Hydro Clutch Conversion Question

[k5blazerguy]

i converted my 79 blazer to 465/205 12 years ago, sold it soon after (new baby needed more reliable truck, just life i guess) then just bought it back couple weeks ago!!! been like a little kid with a new toy haha. just happy to get it back.
anyway, so the donor truck was a manual clutch so all was transferred to the blazer. my blazer has been making a grinding sound every time i push the clutch in for the last couple weeks and finally busted yesterday. clutch hit the floor, fork is dangling and have a crack in the bell housing now. Soooooo what a good excuse to upgrade to a hydro clutch right?
so after spending all night on the search button, i think i have most questions answered, i have a hydro bell housing and another set of pedals out of an 80's truck. i just need to buy a MC, reservoir and slave, the only thing is the exact mounting location for the MC? is there a mark to go by somewhere on the firewall?? i got a pic off here of another member that mounted his, but didnt specify how it was mounted......and on the clutch, i noticed that there are a few different part numbers and 11" and 12" available for these trannys, what is everyone running for this kinda setup? im hoping to get it right the first time i drop the tranny and put this in. thanks.

 

[dyeager535]

Your firewall won't be dimpled for the hydraulic clutch unfortunately. I'm *pretty sure* someone here made up a template in cardboard for this. IIRC the firewalls are all the same outside of the dimples, just a matter of figuring out where they go.

 

[k5blazerguy]

so i should be safe just kinda holding the rod at a workable angle and just mark the firewall? i know a ton of people on here have done it just wondered how everyone else drilled theirs and how theirs works?

 

[k5blazerguy]

Do I need an 11 or 12 inch clutch?

 

[dyeager535]

I can't help on either really...my firewall was dimpled. I can say that you can't just drill it, the master bolts to the two support rods that are part of the pedal assembly. So the pedal assembly governs where the holes go.

I'd like to know the "real" story on clutches. Back in the day, I thought everything was 10 or 12". I'd probably measure the surface area on the flywheel, if it's big enough to fit 12", get a 12" clutch.

 

[k5blazerguy]

so doing some google searching,.....check out this link http://www.chevyk5blazer.com/forums...uto-to-Manual-Swap-th350-np208-to-SM465-NP205
guy did a complete swap with lots of pics. useful info there. if that can help anyone else out.

 

[sweetk30]

search hydro clutch under my name in the garage .

few good pointers I found out the hard way on my old truck I did this to .

 

[k5blazerguy]

Thanks sweetk30. Lots of good info u have in posts. I've searched all around and can't seem to find out if I should use an 11 or 12 clutch. I see people saying that they run a 12. Then some people prefer the 11 cuz it's lighter and has the same holding power?? And that the 12 may be a little much? I found out that no one like the "3 finger" and use the diaphram style. Idk much about clutches still learning. Just gonna be dropping a lot of cash into this and wanna make sure it's gonna work ok. I'm just gonna plan on the 11 and see how it goes. Gonna go with centerforce. Thanks for the responses.

 

[dyeager535]

Might want to do some research on the centerforce stuff. I recall somewhere reading they tended to come apart, especially the fancy ones with different than normal parts. If they make a stock replacement, probably not an issue.

The larger clutch is likely to last longer, and less likely to fail in use (slip) due to heat generation. Weight isn't going to be any different since the weight comes from the flywheel not the clutch. With the 465 gearing and the torque of a V8 the trucks are near impossible to stall starting out where a flywheel with more mass may help as you slip the clutch to get moving. I've got a 2004 Hyundai Accent and I still occasionally stall that thing getting moving because it takes a lot more RPM to get moving than the truck. I can run through at least first and second without even using the clutch in 2hi with the truck.