Camarillo

I need advice and guidance please. I have a standard 1990 RS 305 TBI 700r4. Front disc, rear drums. The rear end is about done at 291,000, it is howling on the freeway especially when I let off the gas. Ruled out the outside bearings, so it is presumably the differential or gears within, maybe a carrier.

My main question is if I buy a full new differential assembly and just have someone install it while also installing new carrier bearings and a pinion gear is that a pretty straightforward job for them to do are they going to have to take a bunch of stuff apart and charge more money than just installing the unit and pinion?

I need the camaro for commuting 100 miles plus per day to work ASAP due to my daily driver breaking its transmission.
Money is sort of tight at the moment but I will do what is best for long term dependability.
So my options are

A) pay to have though inspection tear down of the rear and fix what ails it, $$$

B) buy a complete differential assembly and have it thrown in with a new pinion and bearings $$$$

C) spend $150 on a complete used replacement rear axle with drums. This part is 2 hours away from my location. I can do this my self. $

D) Plot twist, I have a used posi complete rear end with disc brakes in my garage. I think it was for drag racing or performance, I remember the previous owner saying it was great but had bad Gas Mileage due to ratio. I would need to change my proportioning valve to make this work, and I can do this work myself. I don’t remember the gear ratio, but knowing the speed is important on the stretch of highway I Travel. I am not confident to do the speedo gear change required for match gears.

What would you do?

Semi related background info, somewhat irrelevant to the differential question.
I have 4 cars for the family, 2 could probably use timing belt replacement (won’t do this myself) one needs a new transmission, and the camaro s whining and howling down the highway. I’ve been using the kids Camry but it has spongy brakes despite bleeding, and really could use a preventative timing belt. Wife’s pilot is finicky with needing a timing belt possibly and loose steering and hesitation in the transmission, Scion xB blew the manual transmission, this has been my daily driver for about 10 years and is a great car despite the transmission. Now I’m faced with either putting in a weak OEM used transmission with 100k miles for about 1800 or buying a remanufactured transmission which will run about 3500 installed. All this trouble hit in the last two weeks.

What at would you do?

TransamGTA350

iTrader: (2)

Well, your A and B are almost the same. At 291,000mi, and the howling sound you are describing, pretty much everything in there is shot. At a minimum, you will need ring/pinion gears, pinion bearings/seal, carrier bearings, axle bearing/seals and maybe axles depending on how worn they are at the axle bearings. The only thing left is the carrier (what you are calling the differential). Your existing non-posi carrier might be OK, or it might be junk. It depends on how it was treated throughout its life. If I was rebuilding that rear end, I would go ahead and spend the money on a new posi carrier. While you are in there and buying the gears anyway, I would personally change the gear ratio to either 3.23 or 3.42 from the stock 2.73. It will wake the car up. This won't be an inexpensive option though. You are probably looking at $1,000-$1,500 for a full rebuild of your existing axle.

A junkyard rear end swap would be a lower cost, but a bit of a gamble. There are probably still a bunch of them out there with under 150,000mi and are still good.

The other rear end you have might be a good option, depending on what it is. Is the rear end out of a 3rd gen F-body and is it a 9-bolt or 10-bolt? If it bolts right up and is in good condition, that may work for you. A quick way to figure out the ratio is to count the revolutions of the pinion with one turn of the axle. Even better is to take off the cover, count the teeth on the gears and get the number stampings off of the gears. In your car, I would be OK up to 3.73's, but if I were to pick a ratio, 3.42 would be my preference. Changing the speedo gear is easy. Regarding the proportioning valve, you could either swap the proportioning valve, or just swap the drum brakes over to the replacement axle if it is also a 10-bolt.

Not knowing what the overall condition of your car is and what your future plans are, it's hard to make a recommendation. If it's a decent daily driver and you don't want to spend a ton of money to fix it, I would probably first investigate the replacement rear end you already have. If that doesn't work out, then I would look for a good used one.

Regarding the Scion, it's not thirdgen related, so it doesn't really belong on this forum, but I'll give you my 2 cents. In general as with any older car, you need to decide how much money you feel comfortable putting into it, compared to the value of the car and compared to the cost of replacing the car. Maybe a used transmission for $1,800 is still too much to spend on the car compared to its value (depending on mileage, condition and age), but it may still be your lowest cost option compared to replacing the car with something else. A new transmission for $3,500 probably doesn't make sense.

Aviator857

Lots of bone yards will give you a 30 day swap out warranty on the rear if you ask them for it. If you can get that I would go that route.

I would find out what the other rear is, if its a built rear you can sale it and use that money to fix the thirdgen. Or possibly trade it to a shop to rebuild your existing one.

Assuming you have a smart phone install a GPS speedometer and mount it in the car, you can use this for your speed until you save enough to buy the parts to change your speedometer.

As for the Scion xB I bet it crosses to other Toyota transmission I would find a forum for that and see if there are any easy swaps that will give you an upgraded trans, or at least other options from the junkyard.

Personally I would say pick a car sell the rest and fix it up so its 100% reliable daily.

I guess the other question is if you can do a rear swap why can't you do a timing belt?

My diff has 215k miles on it, though its been serviced a few times with new seals and outer bearings. But the pinion/ring has never been out of it. Make sure if its a Posi you put the additive in it.

Sounds like you should find a few u pull it yards... parts are cheap there. The Scion is an interference engine so if the timing belt breaks you bend stuff.