Rear end swap

[lamont]

My 1985 has a bad roar in the rear end and it's not the wheel bearings. Changed gear oil with no improvement. I have access to a parts van and just wondering how big a job it is to swap the entire rear end out? Or could the gears/differential just be changed out?

[blakebecker37130]

Lamont,

I did this repair to my 93 previa. Same basic concept. I could not get the axles unstuck, no matter how hard I tried? You need to pull the axles free on both sides and remove the drive shaft in order to remove the carrier assembly, also referred to as 3rd member assembly. I ended up finding a donor van for 500.00, that was in running condition. I just ended up swapping the rear axle assembly over. The job took about the same amount of time as the carrier assembly swap would have taken. I also scored a ton of other good donor parts. I ended up scrapping the donor van for $250.00 and the scrap yard came to me, to haul it away. My estimate is that I have saved my self-many hundredsof dollars by going this route. I recommend this activity. Hope this information helps.

Best regards,
Blake

[amcneill]

im going through the same problem, and not having any parts vans nearby ive done some research and i *believe* that a few other vehicles had the same rear 3rd member including previas and cressidas...there may be more and they may not even fit but from what ive read they should be the same differential code

[Vanavanav]

Hey everyone, I am very new to the vans. Been working on my 1989 2wd LE and the rear end makes a ton of noise. Sounds like a roaring/whirling/almost like water bubbling but no clicks or bangs. I think the gears are worn out in the dif so I was planning on swapping it for one from a pick n pull. Is it much easier to swap the entire back end (everything from the drive shaft to the brakes) or can I get away with swapping the differential alone?

From what I understand you pull the axels out a bit and then just unbolt the dif case and the drive shaft. Is there some process of alignment when i'm installing the new one that is going to severely jam me up? Again, I'm definitely not a mechanic and I'm trying to avoid creating an even bigger problem.

Thanks!

PS. I apologize if this was covered, I know Tim on one thread said he would recommend replacing the whole axel housing but I am looking for more info.

[blakebecker37130]

No problem, happy to contribute to the cause.

Best regards,
Blake

[amcneill]

hello!

i have had a similar noise in my van for quite some time, and after spending way too long searching for a parts van with a compatible diff, i tried installing one from a mid 80s 2wd pickup. it was completely bolt in, took me about 2 hours to pull the axle shafts, unbolt the driveshaft and remove the third member. installation was just the same in reverse, no alignment needed. im sure there are many other rwd toyotas with F code diffs that could be used, but 2wd pickups are plentiful at pick n pull so it makes sense to try that first!!

i replaced my 4.10 gears with 3.70 and there was no issue fitting into the axle housing!

[bushcat]

I have an 88 4wd auto that I believe has a bad rear end. I have a 1988 2wd 5 spd parts van. Can these rear ends be swapped? If not, are there rear ends other than an auto 4wd that I can swap (truck, etc.). Thanks!

[originalkwyjibo]

You can't swap the complete rearend because of the different axle bolt pattern. You could swap the center section but 4WD Autos are an odd 4.778 ratio and gearsets are hard to come by. Check the ID tag on the floor in front of the passenger seat for axle codes. Unless your differential gearset itself is damaged and the actual cause of the noise you would be best served by having the bearings in the carrier and axles replaced either by yourself if capable or someone who is. An alternative that can save a little if your not capable of the gear work yourself would be to pull the axles and center section on your own. You can then take just the center section in for rebuild.

[bushcat]

Excuse my ignorance but is it not possible to swap a rear end with a different gear ratio?

[originalkwyjibo]

On a 4WD the ratio of the front and rear differential must match. A small variation of a couple hundredths is acceptable such as 4.09 in one axle and 4.11 in the other. If the ratios don't match than the front tires will be trying to rotate at a different speed than the rear tires. This will cause a binding condition somewhere in the drivetrain and if you are not on a low traction surface, i.e. sand, snow/ice, mud, etc which will allow the tires to continually slip to make up the difference than breakage will occur somewhere. The same is true for running different size tires on the front and rear of a 4WD. Given the somewhat light duty construction on some of the vans components, in particular the rear driveshaft, breakage is likely inevitable even on a low traction surface.
All that said, if you have no other option, you could do the swap or run different size tires if that was your need as long as you never engage the 4WD. Perhaps even physically disabling it to prevent accidental engagement in the event someone else drives your van or you are the forgetful type.

Since this is not a 4WD specific thread, I will add If working on a 2WD a ratio change is less of an issue. You just have to keep in mind that speedometer accuracy and performance will be affected.