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#21
Retired Mech Design Engr
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In addition to changing the differential ratio, you may consider:
This if you are using EBC with MS
And, the thought that you do not have to use all the gears, every time. I sometimes go 1, 2, 5. 2nd takes me to 55mph, which may well be speed limit, then row right up to cruising (I have a 5-speed). I also often skip just 4th, depending on how traffic is accelerating.
DNM
This if you are using EBC with MS
And, the thought that you do not have to use all the gears, every time. I sometimes go 1, 2, 5. 2nd takes me to 55mph, which may well be speed limit, then row right up to cruising (I have a 5-speed). I also often skip just 4th, depending on how traffic is accelerating.
DNM
#22
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But as mentioned, it had thicker half shafts, and a different diff centre to suit them (the diff centre may appear larger, but it's the crown/ring gear and pinion that's the important part)
Also look into the Mazda B series/Ford Courier ute diffs.
I can't remember if they used the 6.5in or 7in diff, but pretty sure they often came with taller ratios than the MX5/Miata, so they might be an option to grab cheaper gears (you'll need to confirm yourself that they have the same gear centrelines etc)
#23
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DNM I've definitely got the boost by gear setup and it is a lifesaver. That and the boost by throttle position together and it excellent. It is a must in my mind.
I've got a 3.63 ring and pinion that is slightly worn and I've got all the bearings and gasket coming in the mail. So my next move it to try the swap myself. I'm searching for a shop to handle the swap, but 5 phone calls in, and no one really wants to do it. It is funny how often that is true these days. I had a hell of a time getting all the various shops for my engine rebuild machining work.
I've got a 3.63 ring and pinion that is slightly worn and I've got all the bearings and gasket coming in the mail. So my next move it to try the swap myself. I'm searching for a shop to handle the swap, but 5 phone calls in, and no one really wants to do it. It is funny how often that is true these days. I had a hell of a time getting all the various shops for my engine rebuild machining work.
#24
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Slightly worn should be fine, assuming the crown and pinion are a matched pair (ie: both came from the same diff)
If so, they'll have worn together, so should be fine (assuming it want whining in the original diff)
As far as doing it at home, gaskets are easy.
Crown and pinion swap, less so, but certainly not impossible, it's mostly just slow annoying work setting the lash and crap.
You'll need a decent dial gauge to properly set the backlash, and from memory a micrometer.
a press is pretty much a must have too, since the pinion wont want to move without it
Plus the usual degreaser and loctite to clean it, and make sure the bolts don't shift over time.
(you probably know all that already, since if you're looking to DIY you've probably read up on it already)
edit:
if you havent ordered them, try and replace the bearings too, especially the pinion ones. They sometimes get damaged in the removal process, and saves you a headache later on once it's all bolted back up.
If so, they'll have worn together, so should be fine (assuming it want whining in the original diff)
As far as doing it at home, gaskets are easy.
Crown and pinion swap, less so, but certainly not impossible, it's mostly just slow annoying work setting the lash and crap.
You'll need a decent dial gauge to properly set the backlash, and from memory a micrometer.
a press is pretty much a must have too, since the pinion wont want to move without it
Plus the usual degreaser and loctite to clean it, and make sure the bolts don't shift over time.
(you probably know all that already, since if you're looking to DIY you've probably read up on it already)
edit:
if you havent ordered them, try and replace the bearings too, especially the pinion ones. They sometimes get damaged in the removal process, and saves you a headache later on once it's all bolted back up.
Last edited by hks_kansei; 01-16-2020 at 12:45 AM. Reason: added extra note.
#25
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DNM I've definitely got the boost by gear setup and it is a lifesaver. That and the boost by throttle position together and it excellent. It is a must in my mind.
I've got a 3.63 ring and pinion that is slightly worn and I've got all the bearings and gasket coming in the mail. So my next move it to try the swap myself. I'm searching for a shop to handle the swap, but 5 phone calls in, and no one really wants to do it. It is funny how often that is true these days. I had a hell of a time getting all the various shops for my engine rebuild machining work.
I've got a 3.63 ring and pinion that is slightly worn and I've got all the bearings and gasket coming in the mail. So my next move it to try the swap myself. I'm searching for a shop to handle the swap, but 5 phone calls in, and no one really wants to do it. It is funny how often that is true these days. I had a hell of a time getting all the various shops for my engine rebuild machining work.
PM me if you have questions. My diff has ~12,000 trouble free miles on it and has seen...illegal speeds shall we say.
I also bought a massive 7-8” micrometer for setting the carrier side bearing preload, you’re welcome to borrow it for the cost of shipping to and fro.
#26
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Thanks for the advice guys. I can get the micrometer from work. I did finally find a shop willing to look at it. They quoted somewhere around $300 to do the work. So if they look it all over and feel good about it, I'm going to pull the trigger on that option. As much as I like doing the work myself, without a press, various gear pullers or experience, I fear putting this much HP into it just to damage it all.
#27
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Thanks for the advice guys. I can get the micrometer from work. I did finally find a shop willing to look at it. They quoted somewhere around $300 to do the work. So if they look it all over and feel good about it, I'm going to pull the trigger on that option. As much as I like doing the work myself, without a press, various gear pullers or experience, I fear putting this much HP into it just to damage it all.
#29
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Thanks for the advice guys. I can get the micrometer from work. I did finally find a shop willing to look at it. They quoted somewhere around $300 to do the work. So if they look it all over and feel good about it, I'm going to pull the trigger on that option. As much as I like doing the work myself, without a press, various gear pullers or experience, I fear putting this much HP into it just to damage it all.
I paid a little over $200 to have a local spec miata shop do in mine. So your price for install is not out of line.
#30
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4x4 guys and drag racers are always blowing diffs apart, so most shops that do work for them will usually have decent diff skills.
The $300 sounds ok if you're bringing them a fully assembled diff and getting the C&P swapped.
I think the assembly for my diff was about $150au when it was done, but all the shop needed to do was put it together since the housing/centre/C&P were already separated.
#31
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I'm off hunting two options. One, getrag diff at 3.23, which will require a custom driveshaft and half shafts. Or get a 3.63:1 Torsen from UKPrestigeSpares for $700.
Easy button is the 3.63 for sure. But may just be delaying the inevitable of doing some Kmiata BMW swappage of tranny and diff.
And no, not 260 at the wheels. 400 at the wheels is what I'm at. But I'm babying it.
Easy button is the 3.63 for sure. But may just be delaying the inevitable of doing some Kmiata BMW swappage of tranny and diff.
And no, not 260 at the wheels. 400 at the wheels is what I'm at. But I'm babying it.
#35
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I'm back looking for more advice. Really just a shoulder to cry on.
I got a reputable shop to install some used 3.63 gears I bought into my MSM diff. I bought all new bearings, seals, crush washer etc. Got it in today and it has a horrendous whine.
1st gear, no whine. 2nd gear and up the whine gets really loud and 4 gear it sounds like it is going to self destruct.
So now I have to decide.
1. Could it be something in the installation. Anything I can check?
2. Buy new 3.63 gears ($700) and get the same shop to install those ($400).
3. Consider other possibilities? 8.8? Put the money towards a BMW arrangement?
This is painful. I'm $1000 in and have a large red paperweight in my garage..
I got a reputable shop to install some used 3.63 gears I bought into my MSM diff. I bought all new bearings, seals, crush washer etc. Got it in today and it has a horrendous whine.
1st gear, no whine. 2nd gear and up the whine gets really loud and 4 gear it sounds like it is going to self destruct.
So now I have to decide.
1. Could it be something in the installation. Anything I can check?
2. Buy new 3.63 gears ($700) and get the same shop to install those ($400).
3. Consider other possibilities? 8.8? Put the money towards a BMW arrangement?
This is painful. I'm $1000 in and have a large red paperweight in my garage..
#37
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Update: I paid a local shop to put in my used 3.63 gear set and it whined like a third grader on the way to the dentist. So I pulled it, found it to have way too much lash, tightened it up, put it back in and WHINE WHINE. Terrible noises. So the gearset is a bust.
So I now want to push the easy button. Someone help me find that button please. I want to ship it to someone who knows what they are doing (nobody in the Colorado front range area knows how to do the swap?) and use all new parts.
Lesson learned so far: $250 used gears + $250 misc bearings, washers, etc + $400 labor = useless paperweight.
QUESTION: Would you go with the 3.308 MFactory set or the 3.63 Mazda set? I would be happy if they 3.3 is a good choice, but I certainly do not want to end up with a noisy *** end (again).
So I now want to push the easy button. Someone help me find that button please. I want to ship it to someone who knows what they are doing (nobody in the Colorado front range area knows how to do the swap?) and use all new parts.
Lesson learned so far: $250 used gears + $250 misc bearings, washers, etc + $400 labor = useless paperweight.
QUESTION: Would you go with the 3.308 MFactory set or the 3.63 Mazda set? I would be happy if they 3.3 is a good choice, but I certainly do not want to end up with a noisy *** end (again).
#40
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Find a guy who sets up diffs for jeeps and rock crawlers like I did, maybe. Someone who only does diffs all day will do better than someone who knows how but only does a couple a year. My used 3.63s are quiet.