first post.

1989 ford bronco xlt with AOD trans, 8.8 rear, borg warner transfercase and 5.0 engine.

makes a clunk noise when i change from reverse to drive or drive to reverse.

crawled under and saw that the yoke on the transfercase comes out 1/2 inch.

what is wrong?

 

do you mean that the yoke literally moves 1/2 an inch out of the transfer case?

 

First off, welcome to FTE and the Big Bronco Forum. We will do our best to get you the most accurate information we can muster.

So are you saying that you get a 1/2" of end play in and out of the T-case at the out put shaft/U-joint yoke? If so, you have a significant issue there. I don't know what secures the output shaft in the B/W t-cases. But I DO know that common causes for the clunking you are dealing with are slip joint in need of lube and/or a dying double cardon U-joint which would be at the front of the rear driveshaft.

Personally, I would look into WHY you are getting that much end play from the output shaft and yoke assembly.

 

yes, moves out 1/2" either putting it in reverse it moves out and then putting it in drive it sucks back in, but quietly unlike the reverse going CLUNK

i also have a grinding noise when the truck rolls backwards in reverse, in the reverse gear. it progressively gets louder the faster it rolls backwards and whether pushing the brake pedal to slow it down or just the speed it reaches, it catches and makes a loud slap, clunk noise.

i know its transfer case back. i can feel the grinding on the floor shifter for the transfercase when its rolling backwards.

 

its crazy, the sad part about this truck, 3rd engine, 2nd transmission, original transfercase and rear end and it only has 128,000 miles.

by any chance, would the throttle positioner sensor have anything to do with the clunk noise when it goes from 3rd gear to over drive? AOD trans. mileage unknown on this transmission.

 

Nope... would have more to do with a misaligned TV (throttle valve) cable or even the same issue that is causing the clunk between forward and reverse gears. You are creating the same situation with the shift as you are going from forward to reverse you are taking torque off the driveshaft for a very brief instant then reapplying it. The same happens when switching directions. I'd bet you are dealing with a slip-joint or double cardon U-joint issue. Have a search for this here or check out the Red Link in my signature for more details.

 

The output shaft of the transfer case is secured by snap rings and the output yoke/flange is secured by a large nut. It sounds like a possible planetary gear problem to where it is turning out when you put it in reverse gear and turning back in when you put it in drive. I have been told you can get a new planetary gear set but you could get another transfer case for nearly the same cost. As for the clunk, it may or may not cured by the new transfer case. Another possiblity is that when you put it in reverse that the yoke is slipping on the output shaft. So check the yoke and make sure it is still secured to the shaft of the transfer case.

http://www.drivetrain.com/parts_cata...ts/bw1356.html

The above web site shows the break down of the 1356, and it is realitively simple case.

 

does it have anything to do with the transmission causing the yoke to move like that?

should i put my spare case on that has been sitting for 6+ years?

 

Not sure what you mean about the transmission causing the movement. The trans inputs on a female input shaft that is a one piece of the planetary gear set, the high low gear set of the transfer case. The biggest issue with this transfer case is the range shift fork that the plastic inserts usually wear out and you loose reverse due to the fork wearing out an not able to keep the range selector from slipping into neutral. The other issue is the oil pump that rides on the output shaft can sieze and cause major problems. If your spare has all the right deminisions and ouput style, swap it in, fill it up and run it.

While you are at it do as greystreak suggests and lube the slip joint in the drive shaft and check the unjoints in it while it is out. A sloppy u-joint can cause similar clunks and eventually self destruct. A U-joint is fairly inexpensive and good insurance against broken yokes in the drive train.

 

what kind of lube on the slip joint should i use?


when you said the fork wears out and you eventually lose reverse, could that be my transfercase when i am moving backwards and all its doing is grinding, just a sign the fork is slightly engaged?

 

I am not sure on the driveshaft lube, I used just standard grease from the auto store. I think there are better lubes.

On the transfer case, yes. The range selector has a slight bevel cut on one end of the teeth, and the planetary set in high gear have a reciprical bevel cut. When you put the trans in reverse and the range selector is only engaged on this area of the gear teeth, it just simply turns the gear out and puts the transfer case in neutral. Once you put it in a forward gear, it re-engages the teeth.

 

shedding light on the topic again, i removed the driveshaft and inspected it. the u joints are fine, all greases and in good condition. the slip joint was stuck solid so i pulled it apart and greased it.

i made this video specifically on this topic. i hope that the visual will help much better then words. its hard to explain what is happening but by the looks of these worn out parts, you can see what the issue may be.

please watch the full video, the beginning is a recap from this whole topic. thank you

http://www.youtube.com/watch?v=NKCQVtn0xRk

 

Nice Video, looks just like my Bronco, except for that wiggle in the differential, mine doesn't have a wiggle, it's probably a 3.55 ratio. I have a picture of my axle tag in my Garage, I tried to take a picutre of the BW 1356 transfer case axle tag but it's good shiny to get a good read on the numbers, I'll post a picture of it anyway in my Garage.

My 1990 service manual suggest marking the driveline and diff so that reinstallation is proper and the same as before.

How did the slip joint repair go? It seems like the pinion gear and ring gear have a little slop in the operation. I'm no axle repair guy, so my suggestion would be to check-change the oil in the diff, examine the pinion and ring gear teeth for socoring, excessive wear, nicks and excessive chippping. Worn, scored and damaged gears connot be rubuilt to correct a noisy condition.

Get the trans shift issue repaired and the knock may disappear, or spend some time and money and get the diff tightened up.

 

slip joint went ok,

my dad says i can shim the rear end but i am questioning if its possible.

the dif looks good inside. no water, metal, or sludge build up inside

 

From your video and with that many miles, you will have some differential slop, mine is about the same.

Been there, done that with the transfer case. Rebuilding one of these if fairly easy, I've done several now, however, it's cheaper to find a good one from the junkyard, much, much cheaper.

It's true, the plastic pads on the fork fingers do wear out. However, I haven't heard much about the oil pump seizing. What does happen with the oil pump is the finger that keeps the outer portion of the pump from rotating eventually wears through the ridge on the casing. This causes the entire pump to rotate around, rips apart the intake tubing from the bottom of the t-case to the pump, and pretty much starts destroying the internals of the t-case due to lack of lubrication.

I had the exact same problem on my '88 F-250, it would grind while driving. What I learned to do, and have done this to all my t-cases, is I would weld a small piece of box tubing across the end of the pump finger. This created a much greater surface to come in contact with the ridge in the t-case, thereby eliminating the pump issue.

Hope this helps. You can go to a local junkyard and find a t-case for quite cheap, just make sure to get one from a Bronco, as the F-series t-cases don't have a fixed output yoke or a slip joint in the shaft. The entire yoke slips in and out of the t-case on those models.