Ok - Guys... first off what is the 60 foot on a 11 sec Buick (455? i am assuming) That has got to be a pretty stout hit... How much street driving did you do with the Buick. In bracket racing we swap out street gears about every 2-3 years IF you are truly hitting every weekend racing....Just to be safe. As far as the few thousands off one way or another...It unfortunately does make a difference in what your trying to accomplish... ( HARD drag racing acceleration) In a street regular driving vehicle it probably would not have. GM on their gears is only 6-8 thousands for back lash...So if you are off a few thousands you almost most likely already out of spec in the rear... aftermarket gears usually set-up at .008 - .010 ish all depends on the company and what they lap the gears in at for the pattern. Think if you were a few thousands off on a engine main bearing...OH GOD.... lol. Like I said EVEN I goof, the best mechanics goof... I usually find it before it leaves and I always double check the rear after complete set-up is done... Pattern backlash etc. I have had to take apart rears I thought were done and assembled correctly, BUT after rechecked the pattern or backlash the next day I found out it was just not right or backlash was off etc. ??? Why? Human error something like a little spec of dirt too long a work day...setting up the rear... maybe with out the caps being totally torque to check pattern... Can not just leave it and hope for the best cause I am tired of working on the job... got to fix it. The other guy you can not take a fresh set of gears and just smack it off the line with out any break in at all...??? Gear set really Should not have broke.... but just because you think some one is a professional does not mean they can not goof. We are ALL HUMAN. There is always a reason for why stuff fails...Most of the time it is not what we want to hear...HUMAN ERROR... but face it it is usually the cause and no one wants to be blamed. If you deal with someone that is willing to try and figure out why and help take some of the hit your doing pretty good. Good luck guys, May the mechanics Gods be with you and your projects. Jim J D
The few thousand I was referring I should had been more clear on, it was on the pinion preload.......I use solid shim pack there not the crush sleeve....and you only get so many shims in the pack and it's hard to get exacr preload perfectly. Same thing pinion depth. They only make shims so small. Have run into were I might have a .006 and then a .010 but need .008 to be perfect depth. My motor (464) was going mid 1.5 60 times in a c&d weight of 3850. No street time, no tags or insurance. so this does make it hard to break gears in. To help u normally bake in the oven to about 225 and try to get a gear cycle or 2 thus way on metal, but that still not wearing in together on the set up. For that I try to run on the stand a few 20 min cycles, but this is of course no load really. I'm not blaming the gear or anything. But just stating that when I went to that combo......it stopped the breaking. I don't know for sure if the thicker gears may or may not have helped. I'm not a metalulgist, spelling I know, I have no way to test the strength of one tooth from the other, did not measure the teeth to even see if one was thicker than other. Just assumed in the same diameter if I have less number of teeth each tooth would be thicker, thocker metal is normally stronger. I don't think being 1 thou off on backlash is in the same area of problematic as 1 though off in rod clearance... seeing the give you a 3 or 4 window to be in to be cinsider ok. I do run the patterns, have set gears up and perfect on measurements and not get a good pattern. I try to let the pattern tell me what it wants and use the specs as a guideline to aim to. If you pit one toget her that needed to be out of spec to have a good pattern what would you do
Another solid shim user. Please guys solid shims are NOT necessary at all. The crush sleeve will work fine. ( I personally use a crush sleeve in my 8.5 10 bolt race car...) If you install a crush sleeve correctly you will never have a pinion issue. lock tight the nut and stake the pinion nut. your done. As I stated earlier if something is out of spec, you must get it corrected. You can not just say well they did not give me enough shims so this is going to have to do. THAT does not work. You will need to find some or call me I will try to help you. (again why the crush sleeve, locktight and staking the nut will work better for you. ) The 1.5 's with that heavy of a car is pretty tough on gearing ...BUT not totally out of the realm of being able to last and good amount of time racing when gears are broken in correctly. Gear break in for a race car is not as hard as some may seem. do your burn out... if your using a trans brake do a 3000 hit or less or better yet foot the car to the 1/8 mile at about 3/4 throttle and let off then drive to get your time slip and park it for total cool down. Next run - Burn out - 3/4 throttle pass again to the 1/8th mile - get your time slip. cool down totally. Believe it or not that should be enough to do the job. If you can get more 1/8 mile runs in the better with not as much line hit. That has been what I have done for years on race cars ...no issues as far as gear melting etc. The running of the car on jack stands will do pretty much nothing.... Baking in the oven ain't gonna get the heat either. There is just no weight of the car to get heat into the gears to treat the metal upon the cool down. LIKE a sword you have to get it hot and then Quench / cool. Warm just will not do it. Like a camshaft in a motor. too much spring pressure and the cam is toast, not enough it never gets a good hard surface. I just think maybe a bit more in the break in procedure area and you will be good next time you do a gear swap. The more heat up and TOTAL cool downs you can get those new gears the better they will surface harden for your monster torque mobile. Good luck on the rears... I am just trying to help... not trying to cut anyone down. Jim Mitschke J D
Nah jim your all good, glad to get new info to help out. I was following recommendation's of others when I did my installs. It one thing I love about this site is almost all the info is geared at helping, almost never do i read something geared towards putting someone down. Unlike alot of other sites So you say solid pinion spacertain not needed for my race application? We are transbraking about 4500. I wasnt so much worried about the nut coming loose as much as banging on the sleeve on launch and causing it too loose preload. I hate the solid pinion, PITA to set up. The sleeve is much easier once you actually get it to move. If a few 1/8 mile semi loaded runs is all that needed to break in I can get that out on the roads even though I gave no tsgs. I remember in school they told us it took 250 or so miles to fully break in.
break in- It is heat up and long cool down quench that does the gears real good. I use a 5000 trans brake stall - YOU HAVE TO stake that NUT! If you do not you will likely have the nut loosen deal. As stated I know some like the idea of the solid crush sleeve...BUT many get the preload wrong cause it really takes time to get it absolutely correct. Too loose or too Tight.... Try it with a pointed steel punch into the nut tapered edge of the nut where it almost meets the thread. couple of spots. YOU do not need to goes nuts just enough to mangle the nut into the thread a bit. We never have nuts backing off -
I total agree the solid shims suck to set up, normal apart 5 or so times to get it right. I also used shims being the large cup to help get pinion depth in specs, I have tried the bearing and seems like when I get it on with it the switch to my bearing that's pressed on there is always a small difference in either the bearing, or how far it's pressed on compared to the test bearing. I just find it less frustrating to used a small shim between the bearing and pinion then put the rest behind the cup.
you have to use the bearing your going to do the final set-up with...THAT is why your loosing it. NO other way. Can not use a set-up bearing for solid shim. Jim
