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I am going to replace the diff and subframe bushings on my sc300 in a couple weeks because they are shot. I know I can probably reuse the same bolts, but would it be worth it to replace any of them? If so does anyone have part numbers or should I go to a fastener place and get high grade bolts?
Mainly talking about this rusted part that has an arrow. Is this like a washer attached to the bolt and if not will it be re used if I install poly bushings.
Last edited by Billy305; Jul 22, 2021 at 08:34 AM.
If you pull them and they aren't corroded I don't think I'd bother... If you choose to, OEM or high quality hardware from a metric supply store will do just fine!
You won't find a better bolt in the aftermarket world unless you pay a small fortune. If you want to replace specific parts enter your VIN here although at this point vehicle specific parts are becoming NLA.
I often soak rusty parts in Evapo-Rust then paint with
A friend of nine and I replaced the bushings on the diff and the subframe and neither of us like putting something back together dirty. We cleaned the threads on all bolts with a wire brush wheel and they looked brand new and good for another 220k.
Check the threads VERY carefully and clean them. Both mine looked good on the diff and one stripped on re-installation. We had to install a time-sert to get around it. According the the repair manual, subframe bolts should be replaced upon re-installation but some argue this is not needed. I ended up using all new bolts on my rear end.
The lower 'washers' or cups are to be re-used with poly diff bushings. As per repair manual, some cars have washers/shims from the factory above the stock bushings, other do not. Critical to driveline alignment that you reinstall them with the new bushes if they are present.
Differential Ear Bolts: 90105-12218 x 2 bolts, 108lb/ft
Rear Subframe Bolts: 90119-10679 x 8 bolts, 43lb/ft
Front Subframe Bolts: 52285-50011 x 2 bolts, 129lb/ft
"HINT: Some vehicles have the adjusting shim for adjusting the
propeller shaft joint angle installed on top of the upper
mount stopper. Adjusting shim is not always as it is used upon need.
Install the upper mount stopper on the differential carrier.
HINT:
On vehicles with the adjusting shim installed on top of
the mount upper stopper, install that adjusting shim"
^^ SC_coupe beat me to it with all the part numbers. VERY good point about checking both the bolt threads and chassis threads where those bolts have been. I re-used my subframe bolts the three times I changed my rear differential without knowing that information but now after reading the above post I'll probably pick up a new set of bolts for the future to be safe.
As everyone above has said, replace any of the bolts and other non-rubber parts with OEM if necessary. Also as an alternative to Evap-O-Rust I also recommend Metal Rescue concentrate. I've used that stuff to de-rust many OEM parts that are cast iron and steel. Also bolts, nuts, washers, a ceramic valve with rust on its surface... everything. It so far has not threatened any threads of bolts or threaded holes in various iron and steel parts.
I prime and paint most of these things in appropriately temperature rated VHT spray paints (because VHT spray paints are durable and cheap). For anything heavy duty like a rear differential's iron housing I'll use POR-15 (with a respirator mask) after a lot of careful masking of bolts and areas that need later separation.
I don't think those bolts will go out of production. They probably cross-reference to more Toyota/Lexus vehicles than the SC, Soarer and MKIV Supra. Other much more very SC-specific OEM parts are often what are in danger of being discontinued.
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Billy, if you're going to remove that rear differential to replace the rubber bushings with polyurethane you might as well give it a repaint! I used POR-15's de-rusting spray per their instructions to get the surface back to mostly un-oxidized iron before washing it off, drying with a hair dryer and doing some careful masking with painter's tape (over any bolts and the rear aluminum cover). One little can of the actual POR-15 paint with a one-time-use paintbrush over a use shipping pallet is all it took me to do it.
I second the notes above about reusing. Most bolts in these cars are not torque to yield, other than head bolts, etc so there is no reason to replace them if the threads are still good. One thing to note from someone that has removed a lot of these, just be careful when reinstalling the subframe that you don't cross thread the bolts, it is very easy to do in spite of the fact you would think not. Just make sure everything is pulled up close and hand thread them in the first several turns.
Subframe and diff bolts
