Medium Duty (13" Clutch) np435 questions

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Zpsull01
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Medium Duty (13" Clutch) np435 questions

Post by Zpsull01 »

1. Do the 13" bellhousings have dual patterns like the slant 6/318 poly bells have? I'm trying to determine if a 318 poly 13" bell would also have the b/rb pattern or are they separate bellhousings for the 13" medium duty set-up?

2. Does the 13" bell cause fitment issues in the smaller platform, particularly a D300? We already have the medium duty trans using the 1 3/8" input shaft with a special clutch disc to make it work.

3. Are there any differences as for capacity, max rpm, etc between the 1" and 1 3/8" input shaft sized transmissions? I would expect the large shaft trans to hold up better to higher hp and torque but will it stand up to the rpm's that come with it?

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Re: Medium Duty (13" Clutch) np435 questions

Post by 712edf »

I can answer your first question with a good deal of certainty...... On medium duties the B/RB engines have their own bellhousings. They are NOT the same as A/LA bellhousings.

If the D300 floor will clear the transmission then I don't see why it wouldn't work.

The engines that came in front of the medium duty transmissions weren't significantly different power/torque/RPM wise from the light duty engines. I would think that the tranny wouldn't notice any difference.

Bucky
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1975 W600
1978 W200 club cab

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Re: Medium Duty (13" Clutch) np435 questions

Post by Zpsull01 »

Thanks for the info. I have a mildly built, well headed, 440 that makes around 500hp and easily bounces off the limiter at 6500rpm. I'm not planning on spinning it that hard in this application but am still looking to get at least 5500 rpms out of it when needed. Does anyone know if these transmissions will handle that? We will be using it to tow and haul more than anything.

Also the transmission appears to be the same size but I was worried about the larger bellhousing clearing the floor, firewall, trans tunnel, etc.

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Re: Medium Duty (13" Clutch) np435 questions

Post by 712edf »

A 2" body lift would likely solve any clearance issues with the cab floor, although many people aren't fans of those lifts.

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Re: Medium Duty (13" Clutch) np435 questions

Post by PwrWgnDrvr »

All swept cabs from 300 - 800 are the exact same and mount the same distance above the frame. There will not be any clearance issue. If u lift the cab, the tranny stick won't come thru the floor at the right height. Those trannys came stock behind 361 and 413 torque monsters. They have more beef than most car trannys so I wouldn't fret over it for a second.

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Re: Medium Duty (13" Clutch) np435 questions

Post by Zpsull01 »

PwrWgnDrvr wrote:All swept cabs from 300 - 800 are the exact same and mount the same distance above the frame.
So is there a difference between the 100/200 cabs and a 300? We are in the market for a cab as well. I was under the assumption that the 100's-300's were the same and larger trucks were different.

Does anyone have any idea as to what years/models were offered with the b/rb 13" clutch set-ups that have the frame mounted bellhousings?

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Re: Medium Duty (13" Clutch) np435 questions

Post by 712edf »

Zpsull01 wrote:So is there a difference between the 100/200 cabs and a 300? We are in the market for a cab as well. I was under the assumption that the 100's-300's were the same and larger trucks were different.

Does anyone have any idea as to what years/models were offered with the b/rb 13" clutch set-ups that have the frame mounted bellhousings?
Yes 100/200 are different than 300. I wasn't sure how the 300 was compared to the 400-up but it makes sense since those all had straight frames too.

Frame mounted bells stayed with the medium duty all the way through their last year, 1977. But the latter ones were not identical to the 60's ones. It may have to do with 6-bolt vs 8-bolt cranks.

Bucky
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1975 W600
1978 W200 club cab

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Re: Medium Duty (13" Clutch) np435 questions

Post by 712edf »

Exactly what engine are you trying to mate to that big 435 & what year D300 are you wanting to put them in?

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Re: Medium Duty (13" Clutch) np435 questions

Post by PwrWgnDrvr »

The 69-71 300 cabs are unique to that model. Size and shape they are the exact same as 400 and up, but they use the mechancial clutch so the floor and firewall around the column is different to allow for linkage and pedals. 69-71 400 and up retained the hydraulic clutch of prior yrs and is the same as the 61-68 300-800 cabs.

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Re: Medium Duty (13" Clutch) np435 questions

Post by Zpsull01 »

712edf wrote:Exactly what engine are you trying to mate to that big 435 & what year D300 are you wanting to put them in?
The motor is a 440. Block is a 77 model. Forged crank, 6 bolt.

Truck is a 66 D300 with a dump bed. Currently has a slant 6 with original 11" bellhousing and the medium duty np435. When we bought the truck 3rd gear and the pto both made weird whining noises. When we had the trans out for the throwout bearing we found that the trans was a close ratio and the cluster was damaged due to the wrong pto being installed and not meshing properly. We came to found out that the close ratio cluster is obsolete and there are no pto's offered for that trans. We then went to a bone yard and pulled one from a medium duty truck not noticing the difference in the input shafts. We were able to make it work by purchasing a clutch disc from an early 60's F-250. It took a while and multiple trips to the parts store but we got it to work.

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Re: Medium Duty (13" Clutch) np435 questions

Post by powerwagon54 »

It would be easier to tell which cab is needed if we knew what year and model he needs a cab for.

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Re: Medium Duty (13" Clutch) np435 questions

Post by Zpsull01 »

It's a 66 d300

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Re: Medium Duty (13" Clutch) np435 questions

Post by powerwagon54 »

Then the cab you need is 61-66 300 and up in order to use your doors. If you are getting a complete cab with doors you can use a 61-68 300 and up. 69 up cabs will require a lot of modifications.

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Re: Medium Duty (13" Clutch) np435 questions

Post by Zpsull01 »

Thanks for the info. Is that information as for part interchangeably documented anywhere? I always enjoy reading up on these trucks and how certain years and parts interchange.

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Re: Medium Duty (13" Clutch) np435 questions

Post by powerwagon54 »

only in our minds as far as I am aware.

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Re: Medium Duty (13" Clutch) np435 questions

Post by PwrWgnDrvr »

As Bud said, not in written form. But it is documented in his backyard and mine :lol:
In addition, If you get a complete cab, you can use 69-74 400 and up cabs.

In regards to the tranny beef, they were in trucks that grossed in excess of 30,000#. If they can move that much weight, they can certainly stand up to the output of your 440.
Was it not possible to change the input shaft to the correct size?

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Re: Medium Duty (13" Clutch) np435 questions

Post by 712edf »

So you already have a cab/truck (66 D300) that you want to put a 440 & medium duty NP435 into?

I guess you don't already have the big block hydraulic bellhousing?

Bucky
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Re: Medium Duty (13" Clutch) np435 questions

Post by Zpsull01 »

PwrWgnDrvr wrote:Was it not possible to change the input shaft to the correct size?
I don't remember the exact details but we looked at it and for some reason the clutch disc was the easier/cheaper route in this case.
712edf wrote:So you already have a cab/truck (66 D300) that you want to put a 440 & medium duty NP435 into?

I guess you don't already have the big block hydraulic bellhousing?

Bucky
Correct. The slant feels like it's on its last leg and I currently have the 440 sitting there. Since I already have the medium duty trans I figured I would investigate the 13" route. Plus there's a local bone yard with at least 8-10 medium duty trucks. Hopefully we will get lucky and one will have a big block. I figured I could get the whole setup including motor mounts for well under the price of what a 12" hydraulic big block bell costs.

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Re: Medium Duty (13" Clutch) np435 questions

Post by powerwagon54 »

You are not grasping the fact that the big blocks in those medium duty trucks were 361 and 413. They have 8 bolt cranks and that flywheel is not going to work on a 440.

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Re: Medium Duty (13" Clutch) np435 questions

Post by 712edf »

powerwagon54 wrote:You are not grasping the fact that the big blocks in those medium duty trucks were 361 and 413. They have 8 bolt cranks and that flywheel is not going to work on a 440.
He could get a bell/flywheel from a 74-77 medium duty 361. Those were 6-bolt. I own one. The bells have dual clutch fork access holes, one on each side. It would take some fab work to rig up a fluid clutch, but doable. The only thing about mine is it has a NP540 instead of the NP435.

His easiest (from a parts swapping stand point) route is to find a 1968 383/435 light duty truck set-up, but those aren't getting easy to come by either.

Bucky
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1975 W600
1978 W200 club cab

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