how the heck do i set this backlash?
- Thread starter PeteyAce
- Start date
jackchan
New Member
basically when we did gear jobs we used same shims it came with from factory on both sides of carrier, and the same thickness shim behind the pinion bearing........backlash from my understanding is set with the pinion nut, crush sleeve. Once you get your required 16-23 inch pounds on your collar then you basically just check play in ring gear by setting the dial indicator on ring gear (magnet on housing.......then zero dial indicator)and rock it back and forth. Thats the way we did it and we never had a problem!
good luck
Jack
good luck
Jack
maverick0716
Founding Member
jackchan
New Member
out of all the rear ends we did in our shop, about 38-40........we installed a couple sets of motive gear, couple sets of Richmond gears, and I think one at least of precision gears...all the rest were FRPP gears!....we always used same shims on each side of carrier and same shims or one same thickness under pinon bearings (if one got messed up by a bad bearing or something)......and it always worked for us. But I do agree some gears may differ!
good luck
Jack
good luck
Jack
EMW150
Founding Member
jackchan said:
You're talking pinion depth with the shim under the pinion. I've never had one that took the same carrier shims. Use motorsport gears and use the same shim under the pinion gear and set the bearing preload with the crush sleeve and nut. Reinstall the carrier shims in the origional locations and check the backlash. You'll need to dial this in by mixing and matching shims from left to right or vise-versa. You want 7-12 thousandths. If you have too much, take shim from passenger side and add to the drivers side to move the ring gear closer to the pinion hense : less backlash. Keep about the same total shim thickness to maintain the same carrier bearing preload.
ok, its a real bitch to squeeze these shims in. i put in new bearings and races, ut the total amount of the old pinion has to equal the new amount? like if it was 275 and 270 = 545, i have to use that ame 545? and you guys got any tips for putting in the shims? and how easliy should the ring gear turn once the shims are in?
EMW150
Founding Member
PeteyAce said:
Right if you had 545, try to keep it at that to keep the carrier preload the same. You'll have to juggle shims side to side to either move the ring gear closer to the pinion (less backlash) or if not enough backlash move the pinion away from the pinion gear (More backlash). To get the shims in, install all the corresponding shims on one side and all the thinner ones on the other and then tap in the thickest shim with a hammer and punch. (It shouldn't be a hard hit with the hammer, just a tap) When it's right it takes some doing to get the carrier back out. (usually a pry bar). If it turns too hard you probably are too tight to the pinion and have 0 backlash.
rd
Founding Member
I have done 4-5 of these, 7.5 and 8.8. I cheat, because 14 years ago I made up a case spreader tool, that allows me to install the carrier shims without hammering. I also made a ground flat piece of aluminum to check pinion depth with a caliper.
I also have had the Ford gears go back with the stock shims. I read once that the carrier and gear machining was held closely and the shims were to make up for carrier variations.
I would try first with the stock shims. You could try putting long bolts in the cap bolts and gently prying them apart to assist with shim installation. Most every one just taps them in. Ive done it and it works if you are careful and they are close to the right thickness.
I am not sure that tapping would work with one of the aftermarket stackable shim packs.
I moved my 4.10 gear about .003 to the left after 6 years to reduce backlash from .018 to .011 and it seemed to cure some noise. So, if needed a later adjustment is possible. Note that this set had no more than 100 miles at most of driving.
I also have had the Ford gears go back with the stock shims. I read once that the carrier and gear machining was held closely and the shims were to make up for carrier variations.
I would try first with the stock shims. You could try putting long bolts in the cap bolts and gently prying them apart to assist with shim installation. Most every one just taps them in. Ive done it and it works if you are careful and they are close to the right thickness.
I am not sure that tapping would work with one of the aftermarket stackable shim packs.
I moved my 4.10 gear about .003 to the left after 6 years to reduce backlash from .018 to .011 and it seemed to cure some noise. So, if needed a later adjustment is possible. Note that this set had no more than 100 miles at most of driving.
rd
Founding Member
To better answer your original question, Ford uses a single shim on each side of the carrier, each ground to the desired thickness. If you use Ford shims, you have to buy the assortment. I believe they are available.
For adjustment, an installation kit will include a pair of stackable shims. Each side has a base shim, that is a flat shim with a machined collar at the center. You add a group of varying thickness flat shims to it to get the thickness you want and then install the whole assembly into the axle.
As I noted above, I moved one .003 shim right to left to reset backlash.
The one piece Ford shims are stronger and easier to use if you have to tap them back in with a BFH.
For adjustment, an installation kit will include a pair of stackable shims. Each side has a base shim, that is a flat shim with a machined collar at the center. You add a group of varying thickness flat shims to it to get the thickness you want and then install the whole assembly into the axle.
As I noted above, I moved one .003 shim right to left to reset backlash.
The one piece Ford shims are stronger and easier to use if you have to tap them back in with a BFH.
EMW150
Founding Member
rd said:
The one piece are definately better in my opinion. Didn't like the stacking set like you described. I think Raytech install kits I've used have the one piece.
EMW150
Founding Member
PeteyAce said:
They can seem that way. Turning with the pinion, you're getting the mechanical advantage of the gears. 3.73:1 or whatever gear you're using. When you're turning the ring gear it's the opposite. You're trying to spin the pinion with the ring gear in a 1 to 3.73 ratio which can be a little tough when you just preloaded the pinion bearing and everything's still tight. If your backlash is right, the pinion depth is where it should be, don't worry about it.
EMW150
Founding Member
PeteyAce said:
The click when you're turning back and forth is the backlash. You need to have 7 to 12 thousandths. The movement before the pinion engages and moves the ring gear is what you're measuring. Understand?
cobradvm
New Member
PeteyAce said:
Petey - if you are thinking about using gear compound instead of a dial indicator, to check backlash, it kinda tells me that you don't really know what you are doing or why. I'm not trying to flame here, but backlash is a simply a measurement of the space between two surfaces. In the case of a rear end, it is the distance that the ring gear can move, when the pinion gear is held steady. As said above, it should be between 7-12 thousands of an inch - gear compound can't tell you that! The dial indicator needs to be set up so that the point is perpendicular to one of the teeth of the ring gear. Then making sure the pinion gear can't move, turn the ring gear as far as you can in one direction, then set the dial indicator to zero. Now move it as far as you can the other way, and read what the dial indicator reads - aiming for the measurement stated before. If it is off, you need to play around with your shims - add more to the drivers side to decrease the backlash (ie moving the ring gear closer to the pinion) and the reverse to increase backlash.
The gear marking compound will let you know if you have your pinion depth setup right. If you are using FRPP gears, and reuse the old shim, you more than likely will be fine.
I tried measuring the total thickness of the original shims and then making sure that I replaced the exact same total thickness using a combination of shims on each side so that backlash was ok. That didn't work out so good - there was no way that last shim would go in, so I simply put a smaller one in that was as tight to get in as the original shims - not perfect, but so far no whine!
Good luck and keep asking questions.
jackchan
New Member
its been a while since I've done a gear job, no doubt, but I do remember the first set of gears we installed whined (we used adjustible shims..just like the article in MM&FF suggested).not sure of brand on the adj.shims!) the next time we replaced the gears in this same car (he went from 3.55 in an AOD car to 4:10's the second go round). we put back in the stock shims on both sides of the carrier...........and Every gear job we did we used stock shims on each side of carrier with no problems, no gear whine, and no vibration! The biggest key I did find to NO vibration is putting the drive shaft back exactly the way it came out of a car from the factory. We always marked it before beginning our gear jobs or whatever! Not sure how it was balenced or just what but it always helped keep down vibration. (I'm not talking alot of vibration....but hey I'm picky like that!)...Maybe we were just lucky, and its been awhile, 6-7 years......but if I do a gear job today I'll reinstall the same shims on each side of the carrier as well. Of course I won't install anything but FRPP or motive gear in my rig anyways! When we installed the richmonds they were in a camaro.......and they used same shims as well, and didnt whine or have excessive backlash!
Although there may be some cases where the stock ones wont work.......with certain brands of gear or something. I cant comment on that as I havent ran across that problem yet! I do however agree with your moving the gear back and forth by changing thickness of shims on each side. Seems like it would work to me!
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