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71K5 - BP71K5's Just for fun build

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Edit: I got curious and looked at a crawl ratio calculator. Final ratio looks to be 76:1 (1.9mph and 1500RPM)

Freeway RPM at 65mph is ~1800.

This is based on the following data:
33" tires (33's are actually smaller than 33" aren't they?)
Gear ratio = 3.08
NP205 = 1.96:1
NP203 = 2:1
Tranny = 6.34:1

It looks like going to 4:11 gears would get me over 100. Not sure why, but 100 sounds like a better number than plain 76?
 
From what i've heard the perfect crawl ratio is to match the circumference of your tire.
 
Yea, I heard that too. With 33" tires, it looks like I need to be closer to 100:1 so I guess I'll be short, but I'll try and have some fun anyway.

In any case, the bellhousing got here today. If anyone is interested, 4WP had the bellhousing cheaper than anyplace I could find online. Maybe because the bellhousing is based on a Jeep conversion.
 
Bellhousing arrived today

The bellhousing kit showed up today and it fits just fine. I also got a bracket designed to adapt the GM slave cylinder to the GM clutch fork. It looks like it fits ok, but it doesn't sit quite flat against the bellhousing because they machined one of the surfaces flat, but not the other. It looks like it's designed to mount a few different types of slaves, so maybe I'll have to give them a call to ask if they know about this as well. Maybe I'm not attaching it right.

It looks like I can add a spacer to the machined side (~1/8") to make it level or grind off some material on the other side. I'd rather add a spacer since these same holes are used to bolt it to the motor and I don't want to grind anything structural. Since the clutch fork is on the drivers side, it looks like there is no issue with clearance like the standard GM version.

I test fit it on the motor and the tranny and it looks like it clears the starter and the 168 tooth flywheel ok. I'd heard TRustyK5 had some issues requiring clearancing around the starter.

I also measured the overall length and it turned out longer than I originally thought.

The bellhousing + tranny + 4x4 adaptor = 26-7/8"
The th350+ 4x4 adaptor I have is 24-1/4" long

About 2-5/8" longer than original. Isn't a 700R4 about the same length?

So it looks like I can fix my leaking freeze plug and get a clutch installed. I guess the next item to address is the crossmember under the tranny. I may try and mod the old crossmember or fab up something new.

nv4500 002.jpg
 
I had the same issue with the supplied bracket. I just matched an appropriate sized washer under the bracket to make up for the difference. Watch out for slave interference with the oil filter pad. May not be an issue on SBC but it was on my BBC.
 
I replaced the leaking freeze plug even though I never found any water leaks. The rear main seal will have to wait until I get the tranny back in. You just need to remember that even though you drain the radiator, doesn't mean the motor isn't full of water. That sucked when I popped the plug out.:doah:

Also, after a long fight finding the right clutch, I got on in there. I had a way overpriced centerforce in there at first and then came to my senses that I didn't really need an extra grabby clutch. $450 for a clutch is just wrong.

The problem I'm running into now is the slave cylinder bracket. The bracket from AA is mounted to the bellhousing ok with a washer but the recommended slave had mounting holes that were not even close to fitting on the bracket.

One problem may have been that they recommend a 85 slave and I wanted to use a later version because I'd heard the older version master cylinders had an angled mounting foot that didn't work right in a first gen. I didn't want to try using an 85 slave with a 95 master so I got the 95 matched pair and drilled the bracket to fit the slave. It seems to fit fine even with the oil filter right next to it.

The problem will be adapting the AA replacement slave pushrod to the 95 slave cylinder. Since the AA provided clutch fork is originally designed to be used with a mechanical linkage you need a way to engage the hydralic slave pushrod onto the mechanical fork. It sounds more complicated than it is.

The 95 slave uses a plastic bore in the cylinder and a plastic bushing on the pushrod. The diameter is smaller than the older versions. The AA pushrod is all metal and I'm worried it will goof up the plastic bore in the slave. So the plan is to take the plastic bushing from the 95 pushrod and adapt it to the AA pushrod.

I'm thinking it will be a smart idea to get the master and slave working well before trying to put the tranny in. I've heard there can be some adjustments to the throwout bearing necessary.

Anyway that's it for now. More next week hopefully.

np205 001_1.jpg
 
If you plan on replacing the rear main seal i HIGHLY recommend you do it NOW with the tranny out. WAY easier now than with the tranny in place.
 
My problem with replacing it now is I have a bar holding the engine underneath the oil pan. I gotta drop the pan and oil pump right?

Any tips for supporting it in another spot? I guess I could fab up something to support it from the tranny mount bolts and then go back to the oil pan method once the tranny is ready. Does that make sense?
 
The engine mounts are suffiecent enough to hold the engine in place. I've done it myself so i know for a fact it works.
 
Don't forget you have your whole exhaust system also helping support the back of the engine. I'd do the rear main now whether you think it needs it or not...just because the lion's share of the work is already done. Finding out you need to remove all that stuff 6 months from now would be a kick in the nuts.

I'm glad to hear your bellhousing didn't need grinding at the starter area. That was a real pain in the ass for me.

Double and triple check the re-drill pattern on the face of the 203. The 6 hole pattern the NV4500 uses is identical to the generic 6 hole pattern that was common...except it's mirrored. NWF did the re-drill on my 203 using a 'dummy' adaptor with the regular 6 hole pattern as a guide to transfer punch through. The problem is the NV4500 was used exclusively in drivers side drop applications so in GM's infinite wisdom they mirrored the hole pattern.

I ended up having to elongate one hole in my output adaptor to get it to work, but there was a fair amount of head scratching involved first.

I'd recomend using the actual output housing as a pattern for the re-drill.

In case anyone cares...my crawl is 100.78:1 (5.61:1 first gear) which is 0.62 mph at idle.

Freeway rpm is 1840 rpm on 39.5's (65 mph) and 1920 rpm with the planned 38" michellins.

Did you have your 205 clocked any? Mine is clocked up 3" currently...great underbelly clearance now, but did make drivelines a bit more difficult and spendy. It also played hell with my floor, but apparently I care less about that than you do. :D

Did you find a shifter for your NV4500 yet? Pretty much any 5 speed GM truck from '88 up will work. Even with that broad a search spectrum it took me a half dozen boneyards before I found one. I chose to use the shifter boot from an S-10 though...I thought it looked better.

111aaa009-1.jpg


Floor cutting pic:

111aaa010-1.jpg


Rene
 
Yea, I'm going to replace the seal now. I'm kinda leary of trusting all that weight on just the front mounts and the exhaust, but I'll try it and see how it goes.

Scott had an actual adaptor to use so the hole pattern looks dead on, but I haven't finished building up the 203 yet to confirm. It looks good though.

I did finish putting together the 205 after adding the 32spline input. I also ground the rails to twin stick it. Although I found a good deal on a 32 spline front output that I think I want to swap in so I may tear 1/2 of it open again for that.

ORD clocked the adaptor for the 205 up 2". I'm hoping my floor doesn't need as much trimming as yours, but we'll see. I don't mind hacking up the tranny cover. Could you have gotten away with less cutting?
 
I could have cut a little less, but not a lot less...certainly not enough to make a difference.

Rene
 
So I think I have a good plan for the clutch master cylinder.

I mounted it right behind the brake booster about the same height at the brake pushrod. It's actually mounted to the right of the brake pedal since the stock 71 clutch/brake assembly has the clutch lever there instead of next to the clutch pedal.

I wanted to try and keep the pedal assembly as stock as possible so I decided to modify the pushrod arm so I could take everything off if I needed. The arm has a splined portion that fits onto the splined pivoting rod coming out of the brake pedal. Pictures below.

clutch 040.jpg

clutch 036.jpg

clutch 037.jpg
 
The problem was this arm was not the right orientation for the location I wanted to use the master cylinder. It also did not include the right attachment for the late model master cylinder pushod.

I did have a late model clutch pedal assembly with the right attachment, but it wouldn't properly mount in the stock pedal assembly. So I removed the newer pedal from the assembly and cut it off at the red line in the picture. I also did the same thing on the old lever bracket and I will weld them together (green lines in picture) at the right angle once the MC is mounted and I can set the pushrod length correctly.

I also drilled a hole in the firewall to mount the MC. I've seen some ideas for bolting in a reinforcing plates to the outside of the firewall but decided to make a bracket similar to the stock bracket that goes under the dash (for cosmetic reasons) and prevent the pushrod from pushing the master cylinder bolts out through the thin sheetmetal firewall. The pictures are of the linkage loosly placed together.

clutch 038.jpg

clutch 041.jpg

clutch 043.jpg
 
Last edited:
bp71k5 said:
The problem was this arm was not the right orientation for the location I wanted to use the master cylinder. It also did not include the right attachment for the late model master cylinder pushod.

I did have a late model clutch pedal assembly with the right attachment, but it wouldn't properly mount in the stock pedal assembly. So I removed the newer pedal from the assembly and cut it off at the red line in the picture. I also did the same thing on the old lever bracket and I will weld them together (green lines in picture) at the right angle once the MC is mounted and I can set the pushrod length correctly.

I also drilled a hole in the fireall to mount the MC. I've seen some ideas for bolting in a reinforcing plates to the outside of the firewall but decided to make a bracket similar to the stock bracket that goes under the dash (for cosmetic reasons) and prevent the pushrod from pushing the master cylinder bolts out through the thin sheetmetal firewall. The pictures are of the linkage loosly placed together.
Click to expand...

It looks like you have it figured out!! Good Job! :bow:

I am wondering however if you considered reversing the splined shaft so that the clutch arm could mount to the outside of the master instead of the inside. :confused:

I understand how that all works, I think. :crazy: So I figured that having the clutch mc outside of the brake mc would makle it easier to fill with fluid & therefore bleed, (first of all) & secondly, be a little more logical in layout on the firewall.

Of course, you'd have to reinforce the firewall somehow, so that's another thing to consider. But, maybe you could've just used the late model bracket as-is/was, as long as you could line up the splined shaft with the pivot point on the late model bracket.

Either way seems like it would work to me. But what do I REALLY know? :crazy:

Just thinking & typing instead of working. :D


Later,
Buddy
 
I am wondering however if you considered reversing the splined shaft so that the clutch arm could mount to the outside of the master instead of the inside.
Click to expand...

The splined shaft is welded in place to the clutch pedal. There would be no good way I can think of to change it. The location of the MC is harder to fill over there, but I'm assuming it will rarely need it and there's plenty of room in the engine bay to climb in to take care of it.

The late model bracket was actually modified to fit a first gen truck, but before I got it, I bought a stock pedal assembly so I wanted to keep as muh of that as possible. Both ways might have worked fine, but keeping as many stock parts as possible is one of my goals.
 
bp71k5 said:
The splined shaft is welded in place to the clutch pedal. There would be no good way I can think of to change it. The location of the MC is harder to fill over there, but I'm assuming it will rarely need it and there's plenty of room in the engine bay to climb in to take care of it.

The late model bracket was actually modified to fit a first gen truck, but before I got it, I bought a stock pedal assembly so I wanted to keep as muh of that as possible. Both ways might have worked fine, but keeping as many stock parts as possible is one of my goals.
Click to expand...

Good enough. I didn't realize that the pedal was welded to the shaft. Obviously this will be a great reference for when I swap in a 5 or 6 speed in mine.

Later,
Buddy
 
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