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Discussion Starter #1 (Edited)
This inquiry pertains to the front engine mounting of a 3406c in a 1971 Peterbilt 359. Two photos (below) will clarify the issue and a proposed solution. Comments expressing a different, easier or better solution will be appreciated by the undersigned.

The 359 had a Cat 1693 and the 3406c is replacng it. Photo #1 shows the 3406c sitting between the rails about where it should go. The greasy boomerang shaped 'trunion' had supported the original 1693 in said frame. It's shape does not fit the bottom of the 3406c and in any case would suspend the motor at an incorrect height. Photo #2 is of the 3406c's original blue colored, boomerang shaped 'trunion' under the motor and between the frame rails. Obviously, it matches perfectly the bottom of the 3406c motor but it's span is too short to suspend the motor in those frame rails at the correct height.

Photo #3 is a picture of the bracket on the bottom of the 3406c.

The plan is to remove material from the greasy trunion such that the blue trunion can be welded into the void thereby created....essentially 'marrying' both trunions together to utilize the top edge of the blue one and the length/span of the greasy one connecting to both frame rails. Holes down through each truinon appear to align perfectly.

Questions:
1. Will this proposed part be stout and strong enough? Any idea on what a fair price is likely to be for making up this piece?

2. Is there a cheaper way to accomplish the objective? Is there an aftermarket part available for what must have been a fairly common upgrade at some point in the past; Is creating a new trunion to spec from a single piece of new steel going to be cheaper?
3. Should a blueprint be created from which this part can be manufactured? Milling out the greasy one needs be very precise or will a sketch with measurements to 1/16 inch spec be sufficient? Can shims be used to close any unexpected gaps?

That's alot of questions. Feel free to answer any you think you know have an answer for. :help Much appreciate any and all suggestions.

Roger
 

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I could be wrong but I suspect that the blue one is aluminum,if so your plan to marry them won't work.
 

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Discussion Starter #3 (Edited)
I think you're right K-D. That's why the blue one has the flanges - to lend strength. I guess we'll be heading back to the drawing board Monday morning. Thank you.


PS. The suggestions window remains open......Help!
 

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I think you could have your original mount cut down and add to it a double shear piece. Then bolt the new blue mount to it. It looks like the original mount is just 1/2 inch plate . A double shear piece of 1/2 plate would be plenty strong. That is just my thought.
 

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I would bolt the blue member to the 3406, center the engine support most of the front (engine) weight on the blue member and then build a set of brackets to fit between the frame 90* brackets and the blue member (and put new isolators in the blue member) 3/8 or 1/2 inch steel will be more than strong enough, use grade eight fasteners.
Is the rear of the motor mounted in place ??
 

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Highway to Hell
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I agree that the blue mount looks to be aluminum. My first question is what did the blue mount bolt to. how low did it sit in the frame?

I suspect it bolted to longer "ears" that were bolted to the frame rails. If thats the case just make new "ears" that bolt to each rail that will extend downward to reach the correct position of the bracket. once all 3 parts are bolted it will be rock solid.

Trent
 

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Longhood you beat me to the punch LOL!!!!!
 

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Rather than use an adapter between the frame brackets and the blue engine mount, you could do away with the stock frame brackets and make one piece of steel to go from the blue mount and bolt directly onto the frame where the frame brackets used to be. This would remove one bolted connection for strength and the end that bolts to the frame could be made larger, even put 3 or 4 bolts to the frame if desired. With a good cardboard mock-up it shouldn't take too long or be too difficult to make.
 

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This inquiry pertains to the front engine mounting of a 3406c in a 1971 Peterbilt 359. Two photos (below) will clarify the issue and a proposed solution. Comments expressing a different, easier or better solution will be appreciated by the undersigned.

The 359 had a Cat 1693 and the 3406c is replacng it. Photo #1 shows the 3406c sitting between the rails about where it should go. The greasy boomerang shaped 'trunion' had supported the original 1693 in said frame. It's shape does not fit the bottom of the 3406c and in any case would suspend the motor at an incorrect height. Photo #2 is of the 3406c's original blue colored, boomerang shaped 'trunion' under the motor and between the frame rails. Obviously, it matches perfectly the bottom of the 3406c motor but it's span is too short to suspend the motor in those frame rails at the correct height.

Photo #3 is a picture of the bracket on the bottom of the 3406c.

The plan is to remove material from the greasy trunion such that the blue trunion can be welded into the void thereby created....essentially 'marrying' both trunions together to utilize the top edge of the blue one and the length/span of the greasy one connecting to both frame rails. Holes down through each truinon appear to align perfectly.

Questions:
1. Will this proposed part be stout and strong enough? Any idea on what a fair price is likely to be for making up this piece?

2. Is there a cheaper way to accomplish the objective? Is there an aftermarket part available for what must have been a fairly common upgrade at some point in the past; Is creating a new trunion to spec from a single piece of new steel going to be cheaper?
3. Should a blueprint be created from which this part can be manufactured? Milling out the greasy one needs be very precise or will a sketch with measurements to 1/16 inch spec be sufficient? Can shims be used to close any unexpected gaps?

That's alot of questions. Feel free to answer any you think you know have an answer for. :help Much appreciate any and all suggestions.

Roger
Roger, I have the brackets you need.
 

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Discussion Starter #10 (Edited)
Gentlemen - Thank you. The blue trunion is aluminum so won't weld to the old trunion. The blue one has a set of aluminum L-brackets (2 per side) that secured it to the frame of the 3406c donor truck. W'll be looking into using them without too much hole drilling. An unexpected bonus of their possible use is that they also are aluminum as are the frame rails of the '71 Peterbilt. So the steel will be out after 40 years of galvanic action between the metals.

The rear mouuts are not a probem. There is ample room to move the frame mounts there back or forward a good six inxhes either way.

The problem is the height of the front of the engine....getting it right with a trunion of suffcient strength and top edge conformance with the motor and it's frame attachment at either end. There is a four inch difference in motor height mounted in the frame between the 1693 and the 4306c. Too much adjustment of the engine height will begin to have implications for the radiator and it's support bracket.

Thanks again for your insights. I will post how this issue was resolved and a picture when done.

Roger
 

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Discussion Starter #11 (Edited)
Roger, I have the brackets you need.
Sledman----I didn't see your post before posting moments ago. Obviously I like to discuss with you. Is that possible? Are you selling a set? I'm buying! Or a pic of what you have so my machinist can build a set for me? 23 students will be arriving Monday afternoon and I am trying to help their professor keep them 'busy and benefitting'. Thanks Sledman.

Roger
 

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Sledman----I didn't see your post before posting moments ago. Obviously I like to discuss with you. Is that possible? Are you selling a set? I'm buying? Or a pic of what you have so my machinist can build a set for me? 23 students will be arriving Monday afternoon and I am trying to help their professor keep them 'busy and benefitting'. Thanks Sledman.

Roger
I'm leaving here in a while headed to Jersey. Let me get it off and bring it with me. We can meet in DC.
 

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Discussion Starter #13
Yes. What time will you be throuh here? What exit ramp or fuel stop can we be waiting at so you barely need to slow down as we exchange the envelope for the bracket? How much should be in the former? The part needs get to Western Kenucky. By any luck you don't have a small town US Post Office nearby and a runner who can 'overnite' it to the shop on Monday morning, do you? I can Paypal you isstantly from here now for all costs associated.

I am at 202-575-8719

thx.
Roger
 

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Yes. What time will you be throuh here? What exit ramp or fuel stop can we be waiting at so you barely need to slow down as we exchange the envelope for the bracket? How much should be in the former? The part needs get to Western Kenucky. By any luck you don't have a small town US Post Office nearby and a runner who can 'overnite' it to the shop on Monday morning, do you? I can Paypal you isstantly from here now for all costs associated.

I am at 202-575-8719

thx.
Roger
I am leaving here around 5PM which should put me in DC somewhere around 9:30-10...depending on traffic. Up to you where you want to meet. I go 95 to 495 to exit 19 and take 50 to 301N....so you tell me.

No $$$ right now...make sure it works. I used this same mount to transplant a 3406 in a 74 W900A that had a 1693. You may have to modify a little....not sure.

336-209-3309...leave a message if I don't answer. Me an jr's going outside to throw a few before I leave.

Eric
 

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Discussion Starter #17
Eric: I am headed out to confirm that the clover leaf at 495's intersection with Pennsyvania Avenue (exit 11) is not under construction or anything that will interfere with a smooth handoff followed by your resumption of progress North. I will PM you upon my return. Thanks, obviously. Roger :happydance
 

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I'm leaving here in a while headed to Jersey. Let me get it off and bring it with me. We can meet in DC.

Things like this are what makes this site #1. I can't think of anywhere else that guys can get so much great info and help from so many great people.
 

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Eric: I am headed out to confirm that the clover leaf at 495's intersection with Pennsyvania Avenue (exit 11) is not under construction or anything that will interfere with a smooth handoff followed by your resumption of progress North. I will PM you upon my return. Thanks, obviously. Roger :happydance
Exit 11 has been a cluster for a while, but at night it's usually clear. Exit 19 (Hwy. 50) is the one I take. Trucks usually pull over there and sleep, until DC's finest comes and makes them leave. That's as good a place as I know to try and meet.

Just give me a call around 8 or so.

Eric
 

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Discussion Starter #20
Wooops - I PM'd you before reading this post, Sledman. PM me or advise your telephone cell number and I'll call you at 8 PM sharp and get my hindparts to exactly where you say they are to be. Thank you. Roger (202) 575-8719
 
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