4bt in a bronco

[BJMarshall]

New to the list so please don't give me a hard time if this has already been covered. I have a 4bt from a Frito Lay truck in my 68 Bronco. The swap was relatively easy,and I am very satisfied with the performance. The only problem I am having is the amount of vibration this thing has at idle. I am shaking my truck apart. Any suggestions?

Thanks

 

[britannic]

The 4Bt is kind of known for this, perhaps a bigger harmonic balancer may help? You might look at the engine mounting and see if you can design something that would absorb more vibration. I'm not sure if it's possible to retrofit the counterbalance system that was fitted to certain version of the 4Bt - I'll let someone else chime in here...

 

[LAlessi]

lock washers and loc tite is fixing mine. use RED not blue loc tite

 

[britannic]

LAlessi, how is this fixing the vibration problem for you?

Originally posted by LAlessi

lock washers and loc tite is fixing mine. use RED not blue loc tite

 

[BJMarshall]

I think it is probably keeping his truck together not really doing anything for the vibration. I was doing OK until my horn fell off today.

 

[Steve Graham]

Too much vibration at idle? Make sure its at 800 rpm for hot idle. What motor mounts (isolators) did you use?

I'm planning on drilling 1/2" holes in my 6BTA Dodge mounts (isolators) that I use to see if that will help my Scout.

Live with it, I know that not what you want to here. Sorry. How about some pics of the conversion?



Steve

 

[LAlessi]

tight nuts rattle less. i can deal with the truck shaking, i cannot deal with rattling noises though.



i dont think mine shakes too bad. my dana 60 death wobble is MUCH worse. MUCH MUCH worse...

 

[DKarvwnaris]

The counter balance kits I have looked into for mine were over $1000 so I decided best solution was to bump up the idle a little. I used 12volt swiched high idle solenoid to do this so it isn't always like this. If I am stuck at a stop light, I flip the switch up, it isn't the best solution, but it has helped alot with in town driving. The 4bt I have going into my suburban has the counter balancing kit on it luckily, we had to tear the the engine down due to a shattered front gear set and damaged cam. It is much better, but I could not have justified the cost if it didn't come with the counterbalance kit already. I have seen a few engine shops that had them used off of damaged blocks. These were around $700 or so.

Sounds like your bronco needs the Rolls Royce body treatment. All panels are welded together on them except for the hood, trunk and doors. Very quiet

 

[BJMarshall]

I just kinda keep it idled up with the accelerator. It idles at about 850 normally. This was a little smoother than 800. It's mounted with polyurethane mounts so I know that is not helping either. It is a blast to drive though. I've got 4. 88's and 35" tires, and I am getting about 20 mpg.

 

[LAlessi]

what transmission?

im running 4. 56 and 39s, and like it

 

[BJMarshall]

It's got a 400 in it right now. It works good, but I would like overdrive, and the abulity to lock up the converter. I'm considering putting a 700 in it. What are the other alternatives? Can you hook a NV4500 or a 3550 to it?

 

[BJMarshall]

If anyone cares, I found a major source of my vibration last night. I was checking on a noise I had coming from the flywheel area. I couldn't find it so I pulled the transmission. While pulling it, I noticed the tc bolts were loose. They had gotten loose enough to ruin the flywheel, adapter ( between flywheel and converter), the crank adapter, and it broke the pilot off the converter. $650 later, it is back together and it vibrates much less. I used red loctite on all the bolts this time and I will keep an eye on this from now on.

 

[Steve Graham]

First, off get rid of the polyurethane isolators. That is the worst material for engine isolators or spring bushings, use rubber! I'm using 92 Dodge Diesel mounts, even though their made for a 6B, there not too bad for the 4B,

The NV4500 will adapt to the 4B with the Dodge adapter plate. Use the Dodge Diesel clutch and you won't have any problems. As for the 700R4, I don't know of any one running one behind a Diesel, let alone a Cummins. I don't think it's even used behind a 6. 2 or 6. 5? anyone?



Steve

 

[britannic]

If you put in a 700R4, be sure it's one of the seriously upgraded ones. I got one from Transaction Transmission and Gear in Sun Valley, Los Angeles. Brad and Bernie are my contacts down there. Bernie built me the "Bad Boy" with all of the goodies to handle low rpm diesel torque up to 650ft/lbs. The torque convertor was the heaviest duty they could find. One point they did make, is that all of the T/Converter manufacturers were using a common component inside from GM and that was the limiting factor.



The 700R4 was great, but the T/C destructed behind my high output heavily bombed 6. 2 diesel. Brad rebuilt the 700R4 at no cost to ensure there wasn't any debris from the failed T/C and got me a new converter despite being 2 months out of warranty.

Originally posted by BJMarshall

It's got a 400 in it right now. It works good, but I would like overdrive, and the abulity to lock up the converter. I'm considering putting a 700 in it. What are the other alternatives? Can you hook a NV4500 or a 3550 to it?

 

[Chace TX]

BJMarshall,

Contact me if you might be interested in an auxillary over drive unit.

 

[BJMarshall]

here's a few pics for anyone interested



http://www.superford.org/?vID=4936

 

[BJMarshall]

Someone was interested, but I can't remember who. The Torque converter was a Dacco unit. It's part number is B6. I got it from a friend at a local transmission shop for under $50.