A Question for you gearheads:

[BillyGman]

Okay, this one is for all you guys that have a history of working on your own cars like I do......
I've decided to replace the 4.10 gears that I've just installed about three weeks ago w/4.56's. When I purchased the 4.10's, I also purchased an installation kit that not only included the cover gasket and the marking compound, but the differential carrier bearings, and the pinion bearings as well. However, when I installed the 4.10 gears, I simply re-used the old bearings.
Since My Marauder only has 2700 miles on it, do you think I should just use the old bearings again when I install the 4.56's, or do you think that I should knock the bearing races out, install the new races, and use the set of new bearings that I have? If anyone offers an answer, please keep in mind that I have the proper Snap-On bearing race installation tool set, and for what it's worth, the new bearings are TIMKEN brand.(the old bearings aren't making any noise, and they looked fine when I was doing the 4.10 installation). I'm getting mixed answers from friends on this one.

[looking97233]

I would always use new. Better safe than sorry. Also, I don't know where the cut off is, I mean at what ratio you would need a different carrier. I thought somebody had said that 4.30 was the shortest you could go with the stock 8.8. Of course mabye I'm way out in somebody else's field.

[BillyGman]

Well I dunno. I hope that you're wrong. I never heard of that. Ford makes gears for the 8.8 rear from 2.73's to 4.56's. Richmond gear makes 4.88's also for that rear end. W/Richmond they merely tell you that you have to purchase the special cross shaft pin that they sell for the 4.56's and 4.88's. But according to Summit Racing (That's where I purchased the gears from) you don't need a special pin for the Ford 4.56's. I don't really understand why you would need a special pin for the Richmond 4.56's and not for the Ford gears of that same ratio, but that's what they said.
But thanx for your comments. Anyone else on the bearing thing????

[sailsmen]

I have a client that bid on overhauling 6-71 diesels for the military. The specs called for replacement parts in the rebuild to be inspected and micked.

Items that met factory specs were specifically not to be replaced with new.

Even though this drove the cost up over a standard overhaul the military had determined that the failure rate of an existing proven albiet used part was lower than a new never used part.

With in my opinon world wide quality of all items dropping due to constricted economics resulting in "cost cutting" I will use the exisiting "proven" part that still meets specs.

[BillyGman]

what my brother said too. He said that the old bearings are "proven".......

[Billatpro]

Yes there is merit in this point of view, If ain't broke don't fix it. If the original bearings are in perfect order then there is no reason to not reuse them. Just because a given part is new doe's not mean it's perfect or even good, it just means it hasen't been used yet.

[Kenny's car]

I believe that it is better to replace the factory bearings with a good quality bearing. I understand that the factory uses offshore bearings from the cheapest supplier, knowing that they will have some warranty repairs because of the higher mean failure rate of the more imprecise bearings. I know of failures of the bearings in the rear end of 8.8 cars. If you are going to use high performance gearing and have the rear end open and re-set up, why not put good (like Timken) bearings in?

[BillyGman]

another interesting point. I'm bouncing back and forth w/this bearing thing....but this is good info you guys have been bringing up.....The last gear change that I did, I was able to use a lift(my brother's) however this time around he's not going to let me use it(long & stupid story). So I'm gonna be on my back doing the gear change this time around. So I guess the best thing for me to do is to take a good look at the bearing races to evaluate how difficult it will be to get at them to knock them out and install the new ones. If it doesn't look bad, then I'll have to consider replacing them, but if it looks like it's going to turn into a project all by itself, then that will make my decision easy cuz in that case, I'll just leave the races in there and use the old bearings again.

[frdwrnch]

When I replaced my rear gears I got a used 8.8 limited slip carrier at a swap meet and used new bearings so if I return it to stock it will be quick and easy so I don't have to set it up again. I would recommend new bearings anyway but its really not necessary on the carrier. It is difficult to press the inner pinion bearing off of the pinion shaft so I don't recommend using that one again.

[BillyGman]

told that before about the pinion bearing sometimes coming off of the pinion shaft pretty tough, but what if after pressing the new bearing onto the pinion shaft, you put the pinion in the housing and check the pinion depth w/a depth mic and find that you need more or less shim? In that case you would then have to have the new bearing pressed off and then on again after your shim adjustment anyway. Right??? The last time that i did the gear change, I was fortunate to get the proper pinion depth simply by using the same shim that was on the old pinion. I hope things work out that easy this time around also. But what I did before having the bearing pressed on the new pinion was measure the thickness of both the old and new pinion heads, to make sure that they were the same dimension. And because they were I used the same shim. So I intend to check that this time around too.

[cyclone03]

Believe it or not,I and the guy who showed me how to do gears in the 8.8 have been re using the stock shim in the pinion forever.IF YOU USE FORD GEARS it seems the pinion depth holds very true.Now zoom,strang,richmond all bets are off you better measure the depth.

[BillyGman]

Yes I did use Ford gears for the 4.10's and the 4.56's I'll be installing also are Ford gears. I chose them because of what you just said, and also because all the Richmond gears from 3.90's and numericaly higher make a lot of whining noise even when they're insalled properly, and I don't want that. I knew a guy who had Richmond 4.11's in his 70 Chevelle, and he never had any probelms w/those gears, but riding in that car was like being in a truck because of all the whining. I don't even put up w/the whining from women, so I'm definately not gonna want it coming from the rearend of my car unless maybe it was a 9 second drag car;)

[phil]

WHEN FORD BUILDS THERE AXLE'S THE PINION SHIM IS MATED TO THE HOUSING NOT THE GEAR SET,THAT'S WHY YOU CAN ALWAYS REUSE THE PINION SHIM AND BE OK,IF YOU USE AFTERMARKET GEARS YOU BETTER CHECK YOU PINION DEPTH, BECAUSE IT WILL BE OFF THANKS PHIL

[BillyGman]

even though I'll be using Ford gears agin this time around, I'm still going to check the pinion depth just to be sure it's atleast within 5 or 6 thousanths of an inch or so. it probably will be, but I don't believe that's something that you should ever assume. That's a big job to be doing to your car when you do a gear change, so going by assumption wouldn't be good.

[phil]

YES IT IS ALWAYS GOOD TO CHECK IT AND MAKE SURE, BEEN DOING GEARS AT A FORD DEALER 17 YEARS THE STERLING AXLE PLANT WHERE ARE AXLES ANR MADE TOLD ME ONE TIME THAT THEY GAUGE EVER 5TH HOUSING BUY MACHINE TO CHECK TOOLING, AND 5 T 6 THOUSANDS IS NOT CLOSE ENOUGH ON PINION SHIM. I BET YOUR SHIM IS .029-.032 THANKS PHIL HOPE THIS HELPS

[BillyGman]

Originally posted by phil
YES IT IS ALWAYS GOOD TO CHECK IT AND MAKE SURE, AND 5 TO 6 THOUSANDS IS NOT CLOSE ENOUGH ON PINION SHIM. I BET YOUR SHIM IS .029-.032 THANKS PHIL HOPE THIS HELPS

Thanx a lot for your reply. Yes I agree that you always should check the pinion depth before installing the ring gear. As far as the "5 to 6 thousands" thing, the closer the better. But I guess it would depend on the rear end that you're working on. I got my Marauder within three thousands when I replaced the stock 3.55 gears w/the 4.10's, and I've put 1300 miles on the car since then, and there's no whining or clunking at all. And a few hundred of those 1300 miles were hard ones. I guess you should always come as close as possible to the depth of the old pinion w/that of the new, but the bottom line is the pattern that you acheive w/the marking compound to see exactly where the teeth are meshing. If that and the backlash measurement are right on, then you're good.

[phil]

hey what rpm are you turning at 70 mph with the 4.10 gear. thinking about installing them but do not want to hurt highway driving,and do you know if you can recalibrate the pcm, to get the speedo right,went from 3.27 to 3.55 in my 2000 gt with auto trans and had to chip it. at work we use what is called a WDS to reflash, but with the mustang you can not get perimeters even close to fix the speedo, thanks phil

[BillyGman]

let me ask you....I sent you a PM(Private Message) the other day asking you a question. What happened? You didn't get back to me.
Before the gear change, at 70MPH my Marauder was reving at 2100 RPM in O/D, and 2950RPM in third w/the O/D shut off. And now w/the 4.10 gears, I'm still only reving at 2400RPM in O/D(only a 300RPM difference there) and 3400RPM in third gear(only a 450 RPM change) all at 70MPH. But after the gear change I couldn't even determine all that since the speedo was in error by 10MPH at 70MPH. So I bought the chip from Dennis, and not only did it improve the performance of the car, but it also corrected the speedo error, and corrected the shift points since they too were thrown off by the gear change. But note that not all chips will correct the speedo error. Dennis's chip happens to be one of those that do. So you'll need the chip.
And BTW, I have one of those quartermile GPS devices that you plug into the lighter, and I'm turning .50 seconds faster in the quarter w/the 4.10's than I was w/the 3.55's. But that's also w/the chip installed. My trap speed is 99MPH while it was 94MPH w/the 3.55's. The car still jumps right up to 110MPH in a heart beat, and doesn't begin to strain until you go over 110. So be rest assured, you won't be taking the car off the highway using 4.10 gears since they're not all that extreme w/18" tires that have an outside diameter of 28" like the Marauder does. That makes a difference. Having 4.10 gears in a car w/18" 55 series tires is like having 3.70 gears in a car that has 15" tires that are 55 or 60 series tires, because you're talking about a height increase in the tires of 2" and that makes a subtantial difference. Because the circumfrence of the taller tires is greater, the distance traveled for every one revelotion of the wheel is greater also. Just look at the Monster trucks w/those huge tire circumfrences. All of those trucks get real low gears in the rears such as 6.50's and 7.17's. They need it w/those tires.

[BillyGman]

learned from this experience so far. I'm in the process of installing the 4.56 gears, and upon inspecting the old bearings and races, I've found that the bearing races of the pinion are all scored up, whereas the races of the differential bearings are fine. I think it was a mistake for me to re-use the large pinion bearing for the last gear change I did since the clamshell tool that is used for pressing the bearing off of the old pinion shaft contacts the bearing cage, rather than just the inner portion of the bearing. So I'm glad that I ended up performing another gear change, because I would've never knew this until the bearing race got so bad that it became very noisy, and perhaps even failed. Thuis time around I've knocked out the old races, installed new ones, and will use the new bearings for the pinion. Since the old bearings on the differential look fine as well as their races, and because they didn't have to be pressed off as does the pinion bearing, then I'm leaving them on because the car does only have 2700 miles on it.

[2003 MIB]

Excellent descriptuion of life with 4.10s. I have the DR chip, 180 stat, plugs and 4.10s. I've got nothing but nice things to say about the mods. The highway RPM at 70mph is just as described above. The jump to 100 is better and the firmness of the 1-2 shift around town is much, much better...it can spook the unwitting co-pilot if you're in to that kind of thing....

[BillyGman]

that's agreed....and in a couple days I'll begin breaking in my new 4.56 gears, and as soon as that happens I'll be able to see what those are like in the MM......