Experienced with gear installs? Please read.

[Wes8398]

Long story, but I had a set of gears installed yesterday. The guy who did them runs a racing shop just outside of town. Great guy, and was recommended to me by a few friends. Long story short, he said he's done 1000's of gear installs, and has NEVER had such a tough time getting a set right, until mine.
He said there's usually a number stamped on the gear which helps him with the calculations for backlash, etc. Apparently that number was waaay off. He also said that when he measured the gear (or the ring...I'm not sure which he was referring to, but I thought he said gear), he found that it wasn't "true". He said something about getting a measurement of 3, then measuring again and getting a measurement of 2.5 .... ?
So he wound up having the rear end apart 3 or 4 times because each time he thought he had it right, it would howl when he took it out. They wound up painting the gears and kinda "wingin' it" without being able to do exact calculations/measurements.
I think he's got it set up pretty well, but there's still a faint howl when you're off the throttle and coasting. Right around 2200 rpm down to 1500 or so, then it's not audible anymore. So something's still not right. I think it's a backlash issue when it's a howl when you're off the throttle, right?

Anyway - I bought these from "brenspeed", a shop in the States. Before we get in touch with them about the "****ty" gear they sold me, I need to ask something. Would a gear for an 8.8 Bronco/Explorer, etc be any different from a gear for an 8.8 Mustang?? Or are ALL 8.8 ring and pinions the same?

 

[shaunk]

The 8.8 gears are the same. A well set up gear set should not howl. What brand gears are they? Sounds like the pinion depth is off. At the shop I have a tool to check pinion depth on 8.8's.

 

[ga94gt]

Sounds like they are Ford Racing, because I was told the same thing about mine not having the measurements on the pinion.

 

[Javi]

i have FORD RACING gears and they have measurement visible :dunno:

 

[trav_19]

my ford racing in the 93 had a slight howl when decelerating .... i was not impressed with the quality

i dont even remember the brand of the 4.30's i got ...they were used 3 times down the track he went to 4.56 i got these....they were the easiest gear install i have ever done and make no noise lol it was actually a put it and see what it did type thing and they must have been put in perfectly because they are great

 

[Wes8398]

It was a Motive set-up, which I learned in my investigations, are made in the same place as FRPP gears. I guess Motive is Jeep's version of FRPP; or so I had read somewhere.
Anyway, I really don't think this was an install issue ... well not one that was the fault of the mechanic. He had the rear end apart 4 times trying to get things right. He's a really well known racing car mechanic in the area, and he's a good guy. He said that what was causing the most problem was the fact that he was getting different measurements all the time and was never able to do proper calculations. I'm not sure what/where he was measuring, but one of the measurements he was doing he told me that it showed that the gear wasn't "true", which obviously makes it hard to do calculations.
He said he usually installs Richmond gears and has never had a problem with them. But as I said, he told me that he's never had a gear be such a bitch until he had mine.

I'm going to contact where I purchased the gears from and see what they will do for me considerig so much time was spent by a seasoned mechanic and they're still not "right" since they're whining. From what I'm told, a whine when you're off the throttle is usually a backlash issue ...

 

[trav_19]

how was he getting different measurements?? i really dont understand how he could? :dunno:

 

[xsoutherngun89x]

how was he getting different measurements?? i really dont understand how he could? :dunno:

+1

unless it was just the shimming being different when measuring? i dont see how the gears would change a half inch just by being put in and taken out. then again, I have never done a gear install

 

[Wes8398]

Half an INCH? lol No, no. I'm pretty sure he was talking thousandths when he was saying that stuff. And the reason why he said he was getting different measurements, according to him, was because the gear (or ring, i don't know which he was talking about for sure) wasn't "true" (or perfectly round).

 

[ryclef331]

He's saying the run-out measurement was off. Meaning that the ring gear is just like you said....its not "true." Picture laying the gear on a perfectly flat surface...you'd have gaps under it. This can cause whininig. If the gear isn't true, there isn't really any amount of shimming you can do to fix it. The carrier itself could be warped or it could have been improperly tq'd. I've got motive gears in my car and have zero issues but every car is different. Gears a strange beast. Sometimes they just fall in...sometimes you fight them all day and night. It could be a pinion depth is off or back lash is off or a combo of both...but if he is saying the runout is off, that could be your problem. The crappy part is once they've got a pattern worn into the, you might be stuck with a set of noisy gears till you get new ones.

 

[ga94gt]

He's saying the run-out measurement was off. Meaning that the ring gear is just like you said....its not "true." Picture laying the gear on a perfectly flat surface...you'd have gaps under it. This can cause whininig. If the gear isn't true, there isn't really any amount of shimming you can do to fix it. The carrier itself could be warped or it could have been improperly tq'd. I've got motive gears in my car and have zero issues but every car is different. Gears a strange beast. Sometimes they just fall in...sometimes you fight them all day and night. It could be a pinion depth is off or back lash is off or a combo of both...but if he is saying the runout is off, that could be your problem. The crappy part is once they've got a pattern worn into the, you might be stuck with a set of noisy gears till you get new ones.

I have had the same problem with mine (FRPP) I had them adjusted and now instead of whining on decel and BAD at about 55-60. They whine alittle at 55 and none on decel. I am hoping they will make a new wear pattern and quit all together but that is prolly wishful thinking.

 

[Wes8398]

Thanks for the info Ryclef - very useful. They're really not bad right now at all, so as long as they're not going to get any worse, I can deal with it. It's kinda sounding like a better idea not to mess with it since it's not all that bad right now - it'll likely just make it worse. Like I said, it's just a very faint whine on decel. Nothing else.
The only thing I'm going to try for is to call Brenspeed and tell them that they sold me an inferior product. If I can convince them to replace the gears and pay the labor, then I'll have 'em re-done. If not, I'm just gonna leave 'em as they are. As long as that's a safe thing to do.

 

[xsoutherngun89x]

what gear did you go with BTW?

 

[Wes8398]

3.73 ... and I'm SO happy with the choice!!

 

[Mr. OAM]

Motive Gear has a good reputation. That's what's in my wife's 1966 Mustang with an 8" and it is silent in all conditions.


If the gear is out of round it could be several things such as the center point of the teeth on the gear, radially, not being the centerpoint of the gear itself. In any case, if there is excessive runout the gears should have been removed and replaced by the manufacturer under warrantee. They were machined defectively. I would not have put them back in once excessive runout was found. The mesh of the gears will be inconsistent.

Steve

 

[xsoutherngun89x]

3.73 ... and I'm SO happy with the choice!!

didnt wanna go 4.10?

 

[Wes8398]

didnt wanna go 4.10?
[/quote]
Naaw. It'd be far too much gear for a car that's 99% street driven. 4.10's woulda posed a problem with shifting (auto) too. The 3.73's aren't causing any problems with hitting the rev limiter or anything, so it's great. Still got the JMod coming soon though.

 

[ripper]

Ive talked with Brent (Brenspeed) before and he seemed like a good guy. Im sure he would do the right thing. They are a well known shop and do top notch work. Hope it works out for ya.

 

[trav_19]

didnt wanna go 4.10?

Naaw. It'd be far too much gear for a car that's 99% street driven. 4.10's woulda posed a problem with shifting (auto) too. The 3.73's aren't causing any problems with hitting the rev limiter or anything, so it's great. Still got the JMod coming soon though.
[/quote]

my auto loves my 4.30's... casual crusing it shifts great....if its floored the shift from 2 to drive lags and hits the limiter ....if i spray it with nitrous it shifts 100%....i have no idea why either? :dunno: my first gear was a 3.73 ...i was less then impressed....especially since going larger and seeing how much better it was and surprised at how little the rpms went up

 

[Wes8398]

Ive talked with Brent (Brenspeed) before and he seemed like a good guy. Im sure he would do the right thing. They are a well known shop and do top notch work. Hope it works out for ya.

Brenspeed didn't do the install (in case that's what you were thinking). I just bought the parts from them, and had a local mechanic do the installation. But I am planning on giving them a call on Monday (probably not open on the weekend) to see what they say about the potentially inferior product they sold me.

Trav - when I was referring to shifting without hitting the rev limiter, I meant while driving in "D". I didn't wanna be manually shifting my automatic daily driver all the time. I'd be VERY surprised to hear that you could floor it in "D" and not hit the limiter with 4.30's. At least not without a J-Mod or a tune to change shift command points. When I asked around, I had lots of auto guys tellin me that they had problems w/ the rev limiter on WOT shifts in "D" with only 3.73's. It seems hit-or-miss with 3.73's, but much more common with 3.90's and up.
Like I said, I'm more than happy with the 3.73's - I think they're a perfect "happy medium" between gaining an edge on the track, and maintaining a reasonable vehicle for daily driving (year round, might I add). I'd like to see how far I would go with 4.30's in the snow that we get in South-Western Ontario. LOL The 3.73's are going to be "interesting" enough. haha