While under the van replacing the boot on the front drive shaft slip yoke, I noticed that the passenger side bushing on the transmission crossmember had completely collapsed. It was allowing metal-to-metal contact between the inner and outer bushing sleeves. The driver's side has not gotten this bad yet. I was wondering if this could be the cause of a strange noise I been hearing: It's kind of a clunk and scrape sound that only happens on acceleration. I've temporarily patched the problem by jamming some other rubber bushings into the space between the sleeves:

Picasa Web Albums - eycchu - Aerostar

But I would like to replace the old bushing eventually.

Why did Ford use such a strange bushing design? Is this a Ford-only item? I can't seem to find it at Rock Auto. Can I replace it with a more traditional solid rubber bushing? Also, what is the best way to remove the old bushing shells without destroying the crossmember?

 

My attempts at supporting the crossmember bushings have failed; the passenger side is still sagging enough for the inner and outer sleeves to contact. But that is not the cause of the "clunking" I was hearing.

I think I traced it to the transfer case. So I was wondering, does it matter how the front drive shaft slides into the case output? That is, does it have to engage more than one set of splines, like the input shaft going into the torque converter? I found that I can rotate my front shaft by about 45 degrees, and this is the cause of the clunking. Every time I take off, and the transfer case takes up that slack, it makes a very distinct "clunk". It may have been there for a long time, and just gotten worse and noticeable after I replaced the boot over the splines.

So I'm guessing that the drive chain in the transfer case is stretched beyond serviceable limits. Does this sound right? Is the chain hard to replace? Any special tools needed to replace the chain? Where can I get a replacement? Rockauto does not list it.

As a side note, I removed the E4wd controller a long time ago, so it's been running free for a while. But I still notice that I can not turn the front shaft freely from the rear, like they were somehow connected together, except for that 45 degrees of slack.

Thanks for any help

 

Bushings are not replaceable. Cross member with bushings is/was available from Ford.

A possible noise source is a nearby broken exhaust hanger bracket. There is an exhaust bracket attached to the rear transmission mount. The extension arm from the bracket to the exhaust pipe breaks causing a clunking sound. Hard to see. Try pushing the exhaust to the outside and see if there is a break just before the weld to the exhaust pipe.

 

Thanks Aero. Has anyone tried to reinforce the bushings on the new crossmember so it lasts a little longer?

I checked the exhaust pipe and the hanger that bolts to the transmission mount, and all are solid. Even if they were cracked, I do not believe it is normal for the front drive shaft to have 45 degrees of free play in it. How far can it go before it starts to skip, or break?

If I were to replace the chain, should I also be replacing the drive sprockets? My experience with chain drives on cam gears and bicycles tells me that all those parts should be replaced together. I found a number of sources for the replacement chain; it's a Morse HyVo 048. However, none of those sources say anything about replacing the sprockets.

Also, if I dig into it so far as to replace the chain, I guess I should replace all the seals I find along the way as well? I found one source that sells two kits; a basic seal overhaul kit, and a master rebuild kit that includes the seals and some replacement bearings. Maybe I should keep it simple and just replace the seals?

 

You can get a transfercase for close to $350.00 brand new..I wouldn't consider repairing as parts are outragous. I had to buy a new crossmember for my 94 a while back..I agree kind of a crappy setup. I don't know if the newer transfer case is for you..or not.
NEW Ford Aerostar Transfer Case NOS 92 93 94 95 96 97 : eBay Motors (item 390159503803 end time Feb-25-10 18:15:14 PST)
I would do a low best offer..or call him {hint}

Dick

 

Hey Dick,

Thanks for that link. That is a great price for a complete transfer case, but I don't know if I can use it. Unless I've been mis-informed, the transfer cases changed between 1992 and 1993 when Ford changed the way the speedometer sensor is mounted. From 1990-1992, the speedometer pickup was mounted on the transfer case, so there is an extra hole on those early models for that. The later models do not have the speedometer hole, as Ford started to use the sensor in the rear axle for the speedometer. This could also mean that there is no tone ring in that position on the later models. (Someone please correct me if I'm wrong.)

But they list this unit as being for 1992-1997 Aerostars, which seems to be yet a different set of years.

 

Looking more closely at my transfer case, I realize that it does not have a speedometer cable, as it has a digital dash. So it does not have a gear driven speedometer or VSS, but it has the reluctance type. So could I use the same case as the later model?

 

Uhm, I think you are reading into that wrong. The transfer case has 2 speed sensors which are independent from the sensors used by the ABS and PCM. The transfer case did have some changes over the years, but for the most part it will interchange. I would be careful about before and after '92.

 

I see 3 sensors on mine; 1 on the tail housing, and 2 on the rear part of the housing for the front output housing (driver's side half).

What is the difference between before and after 1992? Since my car is 1990, I think I need something different from this great deal on EBay.

 

Looks like nobody has the answers: what are the differences between the 1990-1991 transfer cases and the 1992 and later models? Is there any way I can get the 1992 model to work in my 1990 van?

 

Hi Eugene,

For the 1992 and later, the front shaft and rear shaft sensors are on the Transfer Case while the speedometer signal comes from the rear differential.

For your van, all three sensors are on the Transfer Case.

That's about all I could tell, and I could be wrong even at that.

I don't know if you really can do anything with the 92 TC to retrofit it to your 90 model. How about rebuilding the TC you have? The chain is not too expensive, and the seal kit is fairly cheap. I think Dave, a.k.a. Aerocolorado, had done it once before.

 

Hi Tung,

Thanks for the reply.

Looks like no one has the definitive answer about all the differences in the two types of transfer cases.

I was looking at various places for the replacement parts to rebuild my TC. I am still wondering if the chain sprockets would also be worn if the chain is so worn.

 

Eugene,

PM Aerocolorado, email him, call him, bug him. I think he has the answer

 

No bugging required, I'm still around.

Eugene, you issue with the preceived 'slop' in the front driveline is something I dealt with a few years back for exactly the same reason. I convinced myself there was excessive play because the chain/gears were worn. Mine wasn't perhaps 45 degrees worth but darn close to that. Anyhoo, I took the TC out and rebuilt the entire case. The old chain measured against the new was almost neglible for wear or stretch. This is on a 1991 E-4WD with over 200,000 miles (well cared for mind you and the original owner). After rebuild, there was still the same amount of 'slop' as before, meaning a rebuild was not necessary. So, you may want to rethink the matter.

As to whether a newer version TC will work in an older model depends entirely on the speedometer type. If your old one uses a cable driven speedometer, then a newer will not work. If your current digital speedo works from a sending unit only (no cable) then a newer version should work. The internals are all the same, case is the same for all models. Only the speedo was different. The only caveat I would throw out would be if the older digital speedo uses a different electrical input/output than the newer ones. This part I am not sure of, but I can't believe there would be much difference.

If you want to rebuild the TC, I would recommend drivetrain.com. Parts ran around $275 and you need a special tool to remove the front input shaft retaining nut. I have the tools and would be willing to loan them out if you need.

 

Thanks for the information AeroC.

Did you decide to do the rebuild because you were chasing down some symptoms? In my case, I have this definite "clunk" (kind of sharp, almost like a "clang") that I could feel through the floorboard on start up. If I start up slowly, it would be delayed, maybe softened. If I start up normally, it comes on pretty much immediately. My first suspicion was loose mounts, or bushings, but other than the nearly collapsed bushing on the cross member, I couldn't find anything loose. I tried shimming up the bushing with rubber blocks, but that didn't change anything. What worried me was my perception that the noise got worse after I replaced the boot on the front drive shaft spline. But I see from illustrations that there really isn't much that can go wrong there, so that must have been my imagination.

I have been speaking to a couple of places that work with or sell transfer cases, and with those guys wanting to sell me a rebuilt case, they all said about the same thing; it's not just the chain that wears, but all the gears and bearings. It doesn't help that Ford/Dana designed it to use ATF, which doesn't provide as much protection as gear lube. So a rebuild really should replace as much of the internal meshing surfaces as possible. So I'm considering getting a complete rebuilt unit from one of these guys.

And I verified that my van has a gear driven VSS bolted to the rear shell of the front drive part of the case. No speedo cable, as I have the digital dash. So I can't use that NOS case advertised on eBay.