Hello again I wanted to get some opinions on the gear pattern I'm getting. This is a set of frpp 3.73 gears that were in my 95 gt for a few years and I just rebuilt the whole rear end. I was getting a pattern just a little bit on the low side at first so I installed a .002" thinner pinion shim which centered the pattern. At .008" backlash the pattern was too far towards the heel so I moved it out to the loose side at .012". Some say you can go out to .015" but my chilton's manual said .012" was the max so that's what I set it at to get the pattern pictured below. I checked the runout on the backside of the gear and got maybe .001"-.002" at the most nowhere near the max of .004". The pinion has the correct preload(around 20 inch pounds) and I used a ratech solid pinion spacer instead of a conventional crush sleeve. I don't know what else I can do except replace the gears if the pattern I'm getting is unacceptable. I can't fool with it anymore to change it I messed with it for a couple weeks with a different number of shim combinations and this is the best I can get. The drive side looks ok I think my only concern is about the coast side. It appears to lean a little too much to the heel but doesn't go all the way to and off the edge of the tooth there is some compound left on the edge. There's no root contact on either side and there is a thin line of compound on top of the teeth on both sides as well. I know you can't get a perfect pattern with used gears but does this pattern look acceptable? Thanks for any help on this
Does this contact pattern look alright???
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I agree a little heavy towards the heel (your pics are small so I can't get a real close look however) and I never go over .012"... Since they were previously used you really need to set them up to the same depth and measurements as they were or they will wear funny and start to make noise, only issue with reusing gears.
Yeah I don't know how to make the pic any bigger I tried to. I changed the pinion shim from a .030 to a .028 so would that be a big enough difference to tear the gears up? I screwed with it so many times trying to get the coast side to move towards the toe. At this point if I have to take it back apart I'm gonna have to get new gears cause there is nothing more I can do. I can't move the carrier any farther away from the pinion and the pattern was worse with the stock .030 pinion shim.
Would these tear up real fast if I try to run them or do you think I could get a couple thousand more miles out of them? Thanks for the help Rick
Yeah I'm thinking these were set up wrong in my car originally and now there screwed. How else could it look good on the drive side and be so bad on the coast side? I guess my only option is new gears but I'll be putting these in myself this time not my step-brother. He didn't measure anything at all back in 04' when he installed them and I didn't know much about cars back then but my gears are obviously screwed up.
Well I talked to a guy at yukon gear and he said I should be mainly concerned with centering the pattern on the tooth between the top and bottom of the tooth. He said heavy toward the toe on the drive side and towards the heel on the coast side is a acceptable pattern for used gears. I even found a chart on their site that showed that as a acceptable pattern. He said that changing the pinion depth by only .002" isn't a big change and that I should be fine in his opinion. The only reason I changed the pinion shim from .030" to .028" was because the contact pattern was too low and into the root. The guy from yukon said it would've been a bad idea to leave it setup with the contact pattern so low and that I needed to make sure it was centered vertically on the tooth.
I know the pic is too small I can't make it bigger but I can say that the wear pattern on the coast side covers half of the tooth with a little bit of compound left on the heel's edge. The yukon tech said that my gears might whine a little at first since I changed the pinion shim but it might not too. He said that changing from a .030" to a .028" isn't a drastic difference and that the gears should wear back together fairly quickly. So I guess I'll leave it at that and see how long the gears last and get new ones if necessary. Lord knows I've had plenty of practice now after setting the rear end up a dozen times and I should have no problem putting a new set in the future.
I know the pic is too small I can't make it bigger but I can say that the wear pattern on the coast side covers half of the tooth with a little bit of compound left on the heel's edge. The yukon tech said that my gears might whine a little at first since I changed the pinion shim but it might not too. He said that changing from a .030" to a .028" isn't a drastic difference and that the gears should wear back together fairly quickly. So I guess I'll leave it at that and see how long the gears last and get new ones if necessary. Lord knows I've had plenty of practice now after setting the rear end up a dozen times and I should have no problem putting a new set in the future.
TenorPlayinGuy
Founding Member
Photobucket does wonders
Never used photobucket I'll check it out and see if I can post some better pics. To sum up the pattern is centered vertically on both sides. It's pretty much in the middle on the drive with a lean to the toe. On the coast side it covers about half the tooth and leans to the heel. There is a small line of compound left on the edge that indicates it dosen't go all the way off though. He said what I described is a average used gear pattern that is normal after the gears have about 100k miles on them which is what I put on these gears. He said that it would've been a bad idea to leave them with root contact so reducing the pinion shim from .030 to .028 was the best I can do and to just go ahead and run em.
Contact FRPP Tech Line (1-800-367-3788), they have a new-revised handout on setting up FRPP gears (hob cut & non-hob cut) that they emailed me last year. If you look at a new set of gears, you can see how they were lapped and want to try to set them up so that they look that way with the gear compound. Ideally, it should have contact across the whole face but leaning toward the lower part on the gear. Normally, if you get the drive side set up, the coast side usually falls into place. I believe the backlash should be in the .008" to .012" leaning more toward the .008". Also make sure your shim packs are not loose and that the ring assembly has to be tapped in with a dead-blow rubber hammer.
Pretty sure my gears are face hobbed I bought them from a frpp dealer in houston back in 04'. The deal is this is not a new set it has 100k+miles on them already. I followed the 8.8 gear install write up from corral and installed .006" extra thick shims after setting the backlash to preload the bearings. I changed all the bearings and used a solid pinion spacer instead of a crush sleeve and have the preload set at 20 inch pounds. I agree with new gears I would make sure to have the pattern perfectly in the middle and picture perfect. But the tech guy from yukon said I'd have to re-machine the entire rear end to get a perfect pattern with high mileage gears. He said I should mainly be concerned with centering the pattern vertically and to make sure the backlash is correct. I started out at .008" backlash but that put the wear pattern pretty far to the toe on the drive side and only covered a fifth of the tooth on the coast side. I tore apart and readjusted the whole thing at least a dozen times and the pattern I have is as good as I can get with these gears.
God knows I have plenty experience doing this now so if I end up having to replace them it'd be a walk in the park.
http://i1140.photobucket.com/albums/n578/ryan7662/ryan02.jpg
http://i1140.photobucket.com/albums/n578/ryan7662/ring2.jpg
Ok I just figured out how to use photobucket so here's some better pics hopefully.
http://i1140.photobucket.com/albums/n578/ryan7662/ring2.jpg
Ok I just figured out how to use photobucket so here's some better pics hopefully.
Stever89
5 Year Member
Only one way to find out.... you've already done the work. Put the cover on, fill it up and drive it. I don't see anything really alarming enough in those pics to warrant another tear down.
I did the same thing a few months back with a set FFRP 3.73 used gears off ebay. The guy sent the gears with the shims it had with it. I used them and put it together, saw a pattern similar to yours (closer to the heel) and it's been fine.
I did the same thing a few months back with a set FFRP 3.73 used gears off ebay. The guy sent the gears with the shims it had with it. I used them and put it together, saw a pattern similar to yours (closer to the heel) and it's been fine.
Cool that makes me feel better I really didn't want to take the rear end back apart again so soon
I already rebuilt the tranny and would like to move on to putting the 351w together and finally getting her back on the road. I figure the gears would probably start screaming like a banshee if they were about to fall apart so as long as they don't get too noisy I'll leave em in. Appreciate all the input guys
Did you change the pinion shaft shim? As I recall, my patterns were not as I desired and much like your patterns but when I went from a .026" to .030" shim, this corrected everything. From what I can tell from your photos, you need more wear to the outside of the ring gear, this might be the answer. Normally, the pinion shim doesn't need to be changed but I think mine was on the lean side as opposed to the preferred/normal pinion shim of .028". As I recall, the backlash didn't change the gear pattern to much. But, I do remember from talking with Ford Tech and few others to stay on the low side of the backlash because in little time, it will be .012" once its broke in .... then it will be right where yo need it and not too loose. From what you described, you are doing everything else correctly. And, if all else fails get a new FRPP set .... they are cheap at $150. But, I think my suggestion might solve your problem. When you see full contact across the tooth you will know you got it and the coast side should then fall right into line. Going from a .026" to .028" pinion shim didn't seem like much from the change I thought i needed so I tried .030" and got it right after a few trial and error tries .... another reason to try the .030 ... I wanted to see a definite change. Hope this helps!
Just re-read your original post, did you try a .032 pinion shim ... since its worn, this might be your ticket. Correct me if I'm wrong here, but your photo is showing more contact towards the center of the ring gear. You want it further out for a more even pattern across the tooth and just a few hairs away from the root of the ring gear. If this is the case, I think going to a thicker shim will do this for you ... sorta what I experienced with my gear set. A thicker shim should pull that pattern back on the ring gear towards the outer from the inner edge. This coupled with .08"-.010" backlash might just do it for you.
I tried it with the stock .030" shim and that was giving me a contact pattern that went all the way into the roots of the teeth. I reduced it too a .028" pinion sim and that centered that pattern on the tooth which is what everyones telling me is the most important thing with used gears. And with the thicker .030" shim the pattern was even farther to the toe on the drive side even with .012" backlash and I barely had a visible pattern on the coast side at all. Thanks for the help and ideas man.
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