Originally Posted by thaeleelyr

I thought 10.9 grade was the highest grade for metric (similar to grade 8 SAE) used for high torque applications, like suspension parts. I thought the inch-pound bolts were around 8 or less (metric, not SAE grade). Am I wrong on this?

Originally Posted by fastnoypi

Thaeleelyr..those grading markings you posted are for standard bolts often used in construction. You won't find them on metric fasteners.

Originally Posted by thaeleelyr

I pulled that out of a service specification sheet for the RX300. I think they are for metric on this vehicle. They are similar but not quite the same as the standard SAE markings. I understand the SAE grade 8 has 6 lines emanating from the hex corners to the center. The grade 8 on this chart is 4 ovals. This could be a bad sheet but so far the torque specs listed below these two charts have matched up with other sources for the RX300. Or maybe the SAE markings changed and I'm not up to speed?

My understanding of the SAE grades compared to Metric are (roughly):
SAE 8 = Metric 10
SAE 6 = Metric 8

The largest bolts I've seen on my RX have been grade 10 metric ('10' stamped on the end, presuming the chart is correct) - those being suspension related. Caliper bracket bolts are marked '8', sway bar bushing bracket bolts have no marks, which, if the chart is correct, puts them at grade 4 - a low enough grade to find at the local hardware store (mine regularly carries SAE grades 6 & 8). I also recall there being no marks on the transmission pan bolts, but my memory is pretty bad.

I was hoping you weren't saying he needed a grade 8 or 10 for such a light application because I've replaced a number of these grade 4 bolts with slightly higher grades from the hardware store but nothing near the metric grade 10 line.

Originally Posted by fastnoypi

iirc they are 10mm heads with 8mm x 1.25 thread. Since its a light torque spec the grade will probably be 9.8 or 10.9 grade. Dealer parts counter should definitely have them. A local auto parts store should have them in the HELP! parts section or you can take a good pan bolt to an ace hardware if you are in a pinch to match up.

Originally Posted by salimshah

For the snapped bolt, the issue is where to grab it. Front (pan side) you may not have enough shaft left. Try the back side and with pliers see if you can grab it with needle nose pliers. If the front is flat (will be able to go through the threads) then you need to ensure there is enough clearance in the back to pull it through and then twist is through. Determine this before you use the priers to damage the threads at the tip. If not then you have to use the tip (extended back) to back out the bolt from the front. If you do back out then quickly switch to the front as soon as you have enough length sticking out to grab. (preserve threads in the tip as they have to make their way through).

Once you past that hurdle, you will have to determine if the threads on the rest of the bolts are good. Back off each bolt and see if the threads are good and you can torque them to spec. For damages thread in bolt you need to get new bolts and for damaged threads in the holes, you will need to tap to the next size. Best would be get a new bolt to test out the threads in the hole and if you can torque a new bolt to spec, you are good.

If you have more than a few holes to tap then I suggest tap all as this will prevent future problems (which bolt goes with which holes).

To test, just take your current bolt to hardware or auto shop. Assuming your hole threads are good and the bolts are messed up, just buy them from the dealer.

For new I would suggest stainless (or consult auto parts). Make sure you get a matching tap. You can switch to non-metric but I would suggest stay with metric and try to use the same pitch of threads but go a mm size bigger. The application has more to do with rust than anything else, so the strength discussion is purely academic

The gasket will need to be replaced as overtorquing can cause leaks. Overtorquing can also mess-up the pan at the bolt points. If the dimples have been formed then they have to be flattened and pushed back. Use a ruler edge to see if the bolt holes have been pushed in. Hold the metal edge ruler on the the side and use a light source in the back.

Final word is that the level of fluid is higher than the joint. So dont try to slap things together.

Salim

Originally Posted by thaeleelyr

hsmac: I found a schematic that shows how to determine bolt strength based on the markings on the head of the bolt but I can't get it to attach to the post. I'll see if I can PM it to you but if that doesn't work I can e-mail it.

Sometimes I have been able to progressively drill a sheared bolt until I can snap it with pliers and I'm able to remove the post without damage to the threads. Maybe you'll get lucky.

Originally Posted by hsmac

yes i did notice yesterday that the bolt had markings on the head and just confirmed it's the #7 with the 3 marks and dot.

i'm going to try to get the sheared piece out now but wanted to first thank everyone for their help. you guys really went the extra mile and have done so in my other posts as well. it's possible my car wouldn't be running right now if it weren't for you guys. i just really want to express my appreciation and hope i can return the favor in the future in one way or another.

Originally Posted by salimshah

Once you past that hurdle, you will have to determine if the threads on the rest of the bolts are good. Back off each bolt and see if the threads are good and you can torque them to spec. For damages thread in bolt you need to get new bolts and for damaged threads in the holes, you will need to tap to the next size. Best would be get a new bolt to test out the threads in the hole and if you can torque a new bolt to spec, you are good.

Salim

Originally Posted by thaeleelyr

I've used that chart enough times that I trust it. A metric grade 7 is roughly similar to SAE grade 5-6. From what I've read, the large national chain stores (Lowe's, etc) tend to carry grade 6 and larger in SAE, so their metric will be comparable in quality. I think you'll be fine checking there. The bolt will be a fraction of the price of that from the dealer and you won't have to wait to get them in. The only negative is that it won't have that black coating that helps prevent rust. Of course, you could always stop at an auto store and see if they have one there but I've never had much luck where I live (Ford country)

I did read two things recently about stainless steel fasteners that have given me pause: (1) there is a chemical reaction between iron and stainless that causes it's own type of corrosion around the bolt. I can confirm this has happened to some of the bolts I replaced with stainless. Whether it is truly a chemical reaction with iron or caused by some other reason i don't know, but it still happened (2) Stainless steel is not as strong as regular steel because it isn't heat tempered. Many SS hardware is around SAE grade 2. Most vehicle grade bolts are SAE 6 and above, so it's obviously not good as a replacement.

SS is also susceptible to galling. Since the bolts I replaced with SS were in low torque areas (plastic dust shields) I'm not too worried, but I may be replacing them later.

Originally Posted by hsmac

i was thinking i just broke a bolt and now the whole pan could be potentially damaged
... snip
.

Originally Posted by hsmac

well..

just as i was going to warn people of how difficult/tedious it is to remove the tranny pan and put it all back given the number of bolts and limited space, one of the bolts snapped as i was torquing it down. i'm not sure what happened, but the bolt snapped near the head where the threads begin, so the majority of the screw is in the hole. thought i would try to put some super glue and try to attach the pieces but it's not catching, and neither is another bolt i removed to try to use.

no idea what to do right now. obviously can't drive the car now and the screw is pretty thin making it more difficult. already pretty frustrated from the job itself and now i have perhaps a huge problem. trying to stay positive hopefully someone can help me out with this predicament.

Originally Posted by hsmac

i did get the bolt out see post above.

seemed like the threads are ok but i'll try torquing them down. hope i won't have to tap as it will take some time to buy materials and learn how to do it. that and the fact that i broke it.

Originally Posted by fastnoypi

you will notice thread damage on the bolt you torque down if the hole threads are messed up after you back it out.. Do not use a tap but rather a thread chaser. They look very similar but the chaser will not cut up damaged threads, rather than persuade them. Accidently cutting new threads may weaken the clamping ability of bolts you use in the hole, unless you plan to go to a larger size. Good luck!

Originally Posted by hsmac

i was impressed when the lady at home depot recognized the bolt as a grade 7 by the markings on the head. the bolts there did not indicate grade but had the class listed on the packaging. she thought they were probably a grade 2 but i later saw a sign saying the class 8.8 bolts were comparable, not equivalent, to grade 5.

not sure if i'm going to install the home depot one first as i need to order from toyota dealer.

Originally Posted by Derrick71

If you have a U-Pull it style junkyard in your area you can go get all the bolts you want. Toyota, Nissan, and Honda all use the same sized bolts for most of the 10mm fasteners on their cars. Just bring one of the originals with you to be sure.

If you haven't been to a U-pull it yard it's easy. Just pay a dollar or two to walk in. Find the car that has the parts you want and pull them off. The parts are super cheap and you can also get things the regular salvage yards (or even the dealer) won't mess with like fasteners or pieces of wiring harnesses. They usually don't even worry about nuts and bolts. It's like having a yard full of parts cars. Just make sure you bring your own tools.