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#11
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Timing belt issue
On 8/30/2012 6:34 PM, Chris D'Agnolo wrote:
> >> >> Let's just say that the "local" Mazda dealer is not known for >> "quality" service. The really experienced and well trained mechanics >> retired, or work someplace else. It's a small dealership, part of a >> large chain, and last I looked, didn't have all the "required" factory >> tools to work on Miata valve trains, and other things. (What shim >> kit, for one) >> When I changed the 5th gear ratio in my 99's 5 speed, I ended up >> borrowing a couple of specialty tools from one of the Toyota dealer's >> mechanics. > > Charlie, You got my attention with your mention of changing the 5th gear > ratio! I've been dreaming of such a modification for years and always > get the same ridiculous answers from other people when I suggest such > (apparent) blasphemy. > > Tell me more please. Feel free to send me a direct emails if you prefer, > I don't want to hijack this thread but, I really would like to discuss > this with you. > > Thanks, > Chris > 99BBBB The 99s used the more or less "classic" Miata five speed. There were parts available in the Mazda warehouse in 2002 or so. Miata.net had some threads and info, at least before they reorganized. It's not difficult to do, but there was a problem that involved borrowing a tool (I ended up borrowing one from an ex Mazda mechanic that was working for the Toyota used car dealer.) It can be done without the tool with some difficulty. I had to take the tranny apart to replace a bad syncro ring, so it was sort of worth while at the time. For the effort involved, I'd rather change the rear axle ratio. The reduction of a few hundred RPM at 70 Mph is not enough to really justify the 5th gear change by itself. The cost of parts was about the same as changing the rear axle ratio. I believe the parts used for the gear change were for an older RX-7 model that had a small rotary engine. There is a spare tranny sitting around that has the changed 5th gear ratio. No, I will not give it away. sadly, used 5 spd trannys go for about the cost of the parts for the gear change. Mazda wanted about 2k for a new one at a racers discount when I bought the spare. |
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#12
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Timing belt issue
>> 99BBBB > The 99s used the more or less "classic" Miata five speed. There were parts > available in the Mazda warehouse in 2002 or so. Miata.net had some threads > and info, at least before they reorganized. > It's not difficult to do, but there was a problem that involved borrowing > a tool (I ended up borrowing one from an ex Mazda mechanic that was > working for the Toyota used car dealer.) It can be done without the tool > with some difficulty. > > I had to take the tranny apart to replace a bad syncro ring, so it was > sort of worth while at the time. For the effort involved, I'd rather > change the rear axle ratio. The reduction of a few hundred RPM at 70 Mph > is not enough to really justify the 5th gear change by itself. > > The cost of parts was about the same as changing the rear axle ratio. > I believe the parts used for the gear change were for an older RX-7 model > that had a small rotary engine. > > There is a spare tranny sitting around that has the changed 5th gear > ratio. No, I will not give it away. sadly, used 5 spd trannys go for about > the cost of the parts for the gear change. > Mazda wanted about 2k for a new one at a racers discount when I bought the > spare. > Thanks Charlie, I appreciate the info. Ya, I would not go thru that amount of work for a couple hundred rpm at 70. I'm looking for more like 1000 rpm reduction at 70! So, I imagine a rear end ratio tall enough to do that would make my little 1.8 noticeably slower in most situations. That's why I thought just changing the one ratio would be the answer. Anyway, I did a tranny swap out this year and had noooo fun at all with it so, realistically, I think I'm giving up on this 'crazy' Miata idea of mine ;-) I still think it's a good one though, 5th gear 'for cruising only' ;-) Later, cd 99BBB |
#13
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Timing belt issue
On 9/1/2012 1:26 PM, Chris D'Agnolo wrote:
> >>> 99BBBB >> The 99s used the more or less "classic" Miata five speed. There were >> parts available in the Mazda warehouse in 2002 or so. Miata.net had >> some threads and info, at least before they reorganized. >> It's not difficult to do, but there was a problem that involved >> borrowing a tool (I ended up borrowing one from an ex Mazda mechanic >> that was working for the Toyota used car dealer.) It can be done >> without the tool with some difficulty. >> >> I had to take the tranny apart to replace a bad syncro ring, so it was >> sort of worth while at the time. For the effort involved, I'd rather >> change the rear axle ratio. The reduction of a few hundred RPM at 70 >> Mph is not enough to really justify the 5th gear change by itself. >> >> The cost of parts was about the same as changing the rear axle ratio. >> I believe the parts used for the gear change were for an older RX-7 >> model that had a small rotary engine. >> >> There is a spare tranny sitting around that has the changed 5th gear >> ratio. No, I will not give it away. sadly, used 5 spd trannys go for >> about the cost of the parts for the gear change. >> Mazda wanted about 2k for a new one at a racers discount when I bought >> the spare. >> > > Thanks Charlie, I appreciate the info. Ya, I would not go thru that > amount of work for a couple hundred rpm at 70. I'm looking for more like > 1000 rpm reduction at 70! So, I imagine a rear end ratio tall enough to > do that would make my little 1.8 noticeably slower in most situations. > That's why I thought just changing the one ratio would be the answer. > > Anyway, I did a tranny swap out this year and had noooo fun at all with > it so, realistically, I think I'm giving up on this 'crazy' Miata idea > of mine ;-) I still think it's a good one though, 5th gear 'for cruising > only' ;-) > > Later, > cd > 99BBB The gear change did noticeably reduce the buzzyness a bit at 70Mph. Close as I could tell, the max RPM change was ~500, and the minimum about 250. We changed such things as speedo cal from the factory high reading setting to 1.5 or so miles high at 70, and also changed the tach to read more accurately, unfortunately in the middle of the whole process. The factory had set the tach to hide the fact that the redline computer cutout was actually lower than specified by a few hundred RPM. Mazda and Ford use the US -0 +5 speedo cal standard. Most read about 3 to 4 miles fast at 70 from the factory. GM (Chevrolet) seems to typically read about one mile high at 70. The 5th gear change along with a turbo might increase the 1/4 mile end speed a bit. (Mostly the turbo) The last time I ran the 99 on a strip (2002), the results were consistent with 200-220 HP. The guy in the other lane was running a stock V8 small block Camaro auto, and ended up a ways behind. I backed off just a bit before the light, to keep the track happy with a convertible and no roll bar. The Miata rear wheels like to "hop" with stock suspension, and this slows down the 60' speed. To add insult the 99 is a bit heavy, due to added sound deadening and the things that go with the turbo. |
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