Clutch Master Cylinder and Internal Slave NV4500 (1 Viewer)

[B y r o n]

So just so everyone understands my reasoning here is a little background. My '73 SBC conversion was done years ago using Downey parts mated to my 3 spd transmission. I decided to go with an NV4500 trans and wanted to avoid heat issues I had years ago.

As you can see from the photo the external slave sits right behind the drivers side exhaust manifold. The exhaust manifolds came on the 350 I used and are not the rams horn commonly used which would put the manifold further away from the slave. The positioning caused heat to boil the fluid in the slave and I would lose my clutch until things cooled. I eventually solved the problem by converting to silicone brake fluid which boiled at a higher temperature than conventional fluids at the time.

I'm comfortable with the internal slave and have it on other Chevy vehicles I've owned without any issues.

The purpose of this thread is to try and get first hand feedback regarding the use of the Toyota clutch master and Chevy internal slave. What little information I've been able to find on the site has only been those who have used other than the Toyota master. It was mentioned that even though the Toyota had the same bore, it's shorter stroke was the reason given for selecting an alternative master. The question left in my mind is did they try and adjust the clutch pedal out further before they switched. I remember having to do this when I originally converted to the SBC.

Here is where things sit now until I get more information.

Gen 1 SBC, factory bellhousing (15998496 casting) with a slightly modified inspection shield (had to open the starter hole) as I'd already purchased a Delco direct drive block mounted one which was less expensive than newer gear driven versions which have a smaller nose cone. This shield is the closest I could find and is actually for later one piece rear main seal 5.7L motor. The transmission is a new 2001 - 2003, GBDW coded 4 X 2 HD version (used with 8.1L gas) that had the output shaft changed to the 4 X 4 version.

I'm going to purchase a new clutch master but would like to avoid needing more adapters than necessary if possible. Also, any feedback about the internal slave as far as which seem more reliable, composite or aluminum, would also be appreciated.

Thanks!

I almost forgot; flywheel is 168 tooth with double sprung Mcleod Workhorse pressure plate and 12" disc. 2800 lb. if I remember correctly. Standard version would slip when pressure was put to 33" tires.

 

[White Stripe]

For a Landcruiser I would not go internal slave. Why? Because if your out in the middle of somewhat nowhere and you have a failure, its far easier to swap out an external slave or do some McGyver fix rather than drop the tranny. Instead use a mixture of heat tape and heat shielding. I would think it would be a rather inexpensive route which would be quite effective and easy. I have never heard of anyone using an internal slave on a landcruiser, so you probably won't get a answer on using the stock master.

 

[batcon]

I had a problem with an external slave on my 71 with a sm465 coming out of the sierras. Easy fix, so I agree with White Stripe.

 

[B y r o n]

Guys I appreciate the feedback and have considered it. I just hate to spend more money which will be in the neighborhood or $400 and not include any of the hydraulics. If I keep the external slave setup my original parts with silicone brake fluid work fine even without any shielding.

It's been working fine for years even with the double-sprung Mcleod pressure plate. I just figured since I was updating, that updating the slave might be a good idea. I haven't had any issues with the internal slaves with any of the Corvette's I've owned but I do understand the ability to fix in the field. Maybe someone will chime in.

 

[B y r o n]

Well, I've done a bunch more research on the topic and this is what I've found. One of the GM slave cylinders that fit the NV4500 (1996 - 2002) is part number 15046288. This appears to be one of the aluminum bodied versions and not the cheaper plastic versions. I also noticed that it was also used on Camaro's in the same date range. The reason this is important is because in my search for a better part I found RAM Clutches, no connection to the Dodge brand. I contacted them about what I was searching for and they mentioned that the Universal T-56 kit might be what I needed. Seems the Camaro used the T-56 transmission and so that had parts that worked with it. That part number is 78160. This was the best photo I could find of what was included in the package.

The adapter mounts to the front bearing retainer with the two M6 bolts. The threaded shaft screws in the threaded hole in the adapter and keeps the slave from rotating. -3 AN fittings then screwed into the slave with braided lines attached to each fitting and then a -3 AN coupler fitting on the feed line and a bleeder assembly on the other. The black and anodized shims are used to set the proper clearance between the throwout bearing and clutch fingers.

According to additional information that I was able to find, a 3/4" master with 1" of travel should move more than enough fluid to properly disengage the clutch. I update again when I get confirmation back from RAM.

NOTE: Made correction regarding AN line size. I initially had -4 listed but was mistaken as they are -3. Sorry if this caused any confusion.

 

[B y r o n]

Here is a video I found of how you can replace the seals in the RAM slave, unlike factory slaves. Also, you will note that they have wipers to keep debris from getting to the seals.



I also forgot to mention, although it might have been obvious from the images above, that unlike factory slaves the bleeder and connection are accessible outside the bellhousing.

 

[B y r o n]

Well I got my response from RAM and since the factory slave is shared with the Camaro I ordered their specific kit which includes the lines all the way to the master cylinder, 78165.

I also looked at McLeod units but cost was higher and I was seeing reports of leaking issues. I seriously considered them since they are local for me and they even listed a setup for the NV4500. Besides the reported leak problem I'd read about, their NV4500 unit was sized to work with the larger Dodge input shaft.

Both companies have been around for about the same time but lower price and no leak issues that I could find won out. I should have the parts next week.

 

[B y r o n]

This ain't your run of the mill factory bean counter must cut cost saving parts.

 

[V6toy4x]

Byron,

Small world, so much so I had to join here, my first post. I am doing this exact thing for a 4runner. The unique part of yours is that you state you have the GBDW version from the 8.1. That means you should have a GM 1-1/4" x 10 spline input as opposed to the std 1-1/8" input, is that correct? If so Thank You very much for posting this I can now take hydraulic clutch off the list, I am doing a driver drop 3 link and this will give ma all I need for the upper link to clear.

Thanks
Duane

 

[V6toy4x]

Byron,

I forgot, did you get your 4500 off the 1200 ebay deal?

 

[B y r o n]

Byron,

Small world, so much so I had to join here, my first post. I am doing this exact thing for a 4runner. The unique part of yours is that you state you have the GBDW version from the 8.1. That means you should have a GM 1-1/4" x 10 spline input as opposed to the std 1-1/8" input, is that correct? If so Thank You very much for posting this I can now take hydraulic clutch off the list, I am doing a driver drop 3 link and this will give ma all I need for the upper link to clear.

Thanks
Duane

This is the label from the top cover:

And here is the tag on the left side cover:

Both tag match however, it does have a 1-1/8" 10 spline input shaft.

Byron,

I forgot, did you get your 4500 off the 1200 ebay deal?

No, but I did get if off eBay from vendor "mantrans" out of Wanamingo, Minnesota.

 

[B y r o n]

So now that I've got the clutch back from being rebuilt, the flywheel resurfaced and a new disc I'm able to get my clearance numbers on the internal slave to the clutch fingers. Ram recommends a freeplay clearance between 0.150" and 0.200" to allow for clutch wear so the slave can fully retract without bottoming out. Them provide shims so that you can adjust your clearance if necessary. To do the math you need three measurements; the crank flange mating surface to the block bellhousing mating surface (dimension A), bellhousing mating surface to throwout bearing contact surface (dimension B), and flywheel to crank flange mating surface to finger contact surface dimension C.

Now you would think that since the SBC has been around for eons that part of this info would be on the net, wrong! Because I couldn't find the info or because it didn't match what I measured, if you're going though this exercise yourself measure your parts and don't rely on possible bad info you found on the net.

So first measurement I came up with, crank flange to block bellhousing mating surface or dimension A, was 0.697". The second measurement, bellhousing mating surface to throwout bearing or dimension B, was 3.745". The last measurement, flywheel mating surface to clutch finger contact or dimension C, was 2.881".

So since this is going to all be bolted together you add A + C or 0.697" + 2.881" which ='s 3.578". Now to determine the freeplay you take dimension B and subtract the result you just got from A + C or 3.745" - 3.578" which ="s 0.167". So based on these numbers it looks like I'm golden as far as bolting things together.

There is however one more thing to consider, clearance of the slave adapter pieces and the pressure plate. I extended the slave to full extension and saw that the shaft that prevents the slave from rotating cleared everything.

Now we have another however. The freeplay measurement of 0.167" was with the slave seated agains the adapter. The closest I could come with a spacer to simulate this was an O-ring which measured 0.184". With it between the fully retracted slave and the clutch this is what I ended up with.

As you can see the rod if left the original length would interfere with the clutch fingers which would not be good. Lucky for me RAM thought of this and you can also see they have step cut a cut-off length marked on the shaft if it needs to be shortened. So once I trim the shaft it should be clear sailing with the install. RAM also mentioned that if shortening the shaft make sure the slave does not go beyond the end which would allow it to rotate. You can see in the first picture that I'm good there with a little room to spare.

 

[B y r o n]

Well I got everything installed in the car and ran into a little snag, literally. Seems with everything relaxed the fingers of the Borg & Beck pressure plate had plenty of clearance. However, once everything was together the fingers were catching on the spiral lock on the hydraulic slave. The spiral lock that prevent the throwout bearing from extending too far had to be removed but my only access was the two square ports on the top of the bellhousing and the opening that the lines ran through. With a little luck I was able to dislodge it from the groove with a long pick and then pull it from the housing with a long pair of curved needle nose pliers, the 11" variety. With the ring removed everything was moving freely.

I'm glad the pick and pliers worked because I didn't want to remove the beast (NV4500). Trying to line everyting up and push it in was no picnic.

Time to get the rest of it back together now.

 

[B y r o n]

Well I know is has been a while but I finally got my rig on the road last week. My first day on the road ended with the clutch not disengaging just before getting home. I got it in gear and rolling and limped it home. The next morning I bled the clutch again and all was right in the world again.

First gear is great for creeping into the driveway and off-road but that is about it. Two, three and four are like the old 3 speed it replaced. Fifth make it like my Avalanche in drive, a pleasure on the freeway now.

It's not like a Muncie or T10 setup, it is definitely a truck transmission which is fine with me.

 

[cruisermatt]

@B y r o n

You never specified, are you running a Land Cruiser master cylinder with this setup? I am looking to do the same thing, move my slave cylinder away from exhaust (my exhaust/slave clearance issue much, much, more severe), and I want a slave cylinder with more travel so the clutch engages earlier in the pedal travel.

 

[B y r o n]

@B y r o n

You never specified, are you running a Land Cruiser master cylinder with this setup? I am looking to do the same thing, move my slave cylinder away from exhaust (my exhaust/slave clearance issue much, much, more severe), and I want a slave cylinder with more travel so the clutch engages earlier in the pedal travel.

My post, 4th down, in this thread should answer your question.

 

[Dcon]

B y r o n, great write up! Thanks. 3 years later, is it still working well? I am looking into doing this conversion on my FJ40 w/NV4500 and also a ls/sm465 1972 truck im in the middle of building. Thanks!

 

[B y r o n]

B y r o n, great write up! Thanks. 3 years later, is it still working well? I am looking into doing this conversion on my FJ40 w/NV4500 and also a ls/sm465 1972 truck im in the middle of building. Thanks!

Sorry for the delayed response but yes, everything is working just fine.