Gearboxes are robust ; some power related breakages at 260 hp plus… sometimes they lock you out of reverse – very rare. Some rare noises from gearbox e.g.’98 Berkeley was inspected by a pair of Mazda engineers regarding a noise from the transmission in 4th gear at around 4k rpm – mismatch of tolerances – ignore or rebuild box!

There are two gearboxes;

5 speed (all same ratios) (but the Mk2 has detail differences on tail and bits)

Mk 2 6 speed (which is also fitted to Lexus IS200 with lower ratios and Toyota Silicas)

The Miata comes from the factory with a 20 tooth speedometer gear (for both the 4.30:1 and the 4.10:1 rear gears which makes the 4.30:1 gear about 5mph fast) but this change later.
"1.8i (standard fit wheels & tyres), at exactly 70 my clock read 73mph, this gives an over-read of about 5%, well within the +/- 10% official tolerance"

5peed's sell a Sequential gearbox; 6-speed all syncho touch shift sports gearbox made in England Just 3290 GBP for the gear box and another 360 for the digital display.

Mk2 v Mk1 gearbox

"Well, I've compared the two and the tail is a completely different piece than the M1, but all appears to mount up the same. Bell housing appears identical. The gear change is different with two pins instead of one (hence Mk1 quick shift kits do not fit Mk2). Speedo gear - mechanical connection replaced with electric sender. Old mechanical fit in perfectly, different colored speedo gears. Reverse / neutral switches - same pieces, same spade connections on one, the bullets on the other replaced with a "t" type spade connection." Todd Paciorek

Oil; 80W-90 was only for use above 10degC and 75W-90 for lower temperatures

Gearbox: API GL-4 or GL-5, SAE 75W-90 (All season use)
(2 litre or 2.1 quarts) – need extra litre for the remote change mechanism:

Redline MTL Gearbox (75W/80 GL-4)

An alterative is Redline MT90 (75W/90 GL-4)

Castrol SMX-S Manual Transmission fluid.

Silkolene Silktran Syn 5, fully synthetic gear and transmission oil API GL-5 and 75W-90

Differential: API GL-5, SAE 90 (ie monograde) (above - (minus)18 deg C)

(0.7 litre 1.6 cars, rest 1 litre), 1 quart does it

Redline 75W90

Castrol SAF-XJ Synthetic Axle Fluid SAE 75W-140. Exceeds API GL-5.

Silkolene Silktran Syn 5, fully synthetic gear and transmission oil API GL-5 and 75W-90

Redline Suppliers;

Europa Specialist Spares, Fauld Industrial Estate, Nr. Tutbury, Burton-on-Trent, Staffs. DE13 9HR, England Telephone 00 11 44 1283 815609 Fax 00 11 44 1283 814976 Moss

Demon Tweaks Email: tuning@demon-tweeks.co.uk

75 Ash Road South, Wrexham Industrial Estate, Wrexham, North Wales, UK, LL13 9UG

Phone: 01978 664466 (UK sales); 01978 663000 (Customer Service); 01978 664468 (Wheels & Tyres) Fax: 01978 664467

1. 1.6 Mk 1 (4.3:1) open (standard) .. 200 hp maximum
2. 1.6 Mk 1 (4.3:1) Viscous Limited Slip (VLSD) (special order UK, standard on some Roadsters but these differentials do not last and if used die within 30,000 miles)
3. 1.8 Mk 1 (4.1:1) open (bigger and stronger than 1.6)
4. 1.8 Mk 1 (4.1:1) Torsen (same size as open, Torsen 1 + 2 available but very similar) (TLSD) never fitted in UK, standard some Roadsters
5. 1.6 Mk 2 (4.3:1) open
6. 1.8 Mk 2 (4.3:1) open
7. 1.8 Mk 2 6 speed (3.9:1) Torsen as standard on 6 speed

1. Find a second-hand one .. if you want LSD it is hard .. 1.6 to 1.8 requires driveshaft/prop/housing
2. RX-7 TORSEN-1 from MazdaTrix will bolt right in. You'll want new side bearings and will need to have them pressed on. MZTX-TORSEN1.....DIFF TORSEN LSD....84-92 NON-TURBO...$ 762.95 = £476.85+50=£680 in UK
3. Mazda 1.8 Torsen MM02-27-200A = Torsen LSD = £657.14+VAT=£772.14 in 6-8 weeks from UK dealer94 onwards LSD – might be MM02-27-200A= Torsen LSD (= $612.95 = £383+50=£560 in UK from Mazda competition (need to be US based!))
4. Mazdaspeed clutch type LSD; needs special oil and not as sophisticated as Torsen in delivery

Early Torsens were type 1 with open gears, after ’95 the closed housing Type 2 were supplied.

"Mazda competition sell 4.30 ring & pinion set for $360. The retail price for these gears was quoted at $592. Roebucks would sell the set for $503. Mazda Comp quoted the 4.44 gears at $264. I felt that the $96 difference between the 4.30s and the 4.44s was justified since I would not have speedo calibration issues"

"I have 4.44:1 gears installed. I bought the ring and pinion gears from Mazda Comp but they can be had at any dealer (Roebuck) or agent (Moss, Racing Beat, MazdaTrix). The ring and pinion gears are matched sets and have to be purchased together. i.e. the 3.909 has 11 pinion teeth and 43 ring teeth, 4.10=10/41, 4.44=9/40 (see why the 4.44 is the strongest, it has the fewest teeth) Any driveline shop (check yellow pages) can do the install. Ask if they have done Mazda rears before since the pinion depth is set with a crush collar and is a very trial and error process usually requiring more than one collar before you get it right. Plan to spend anywhere from $200-400. " Randy @ Solomiata

The main external difference between a type 1 and a type 2 is that the type 2 has no output stub shafts on the diff. The axles just press into the diff on one end and the hub on the other end. The diff section with the torsen in it should pull out once the stub shafts are removed, but if it has stub shafts, it's a type 1. If you pull the drain or inspection plug and see gears, then it's not a torsen, it's an open diff. :-(

4000 RPM in final gear:

Mk2 5-speed and early Mk1 1.6: 77 mph

Mk2 6-speed: 82 mph

Mk1 1.8: 81 mph

Mk2 6 speed gearbox with Mk1 1.8 differential: 78 mph

Mk2 6 speed gearbox with Mk 1 1.6 differential: 74,7 mph

Mk1 1.6 at 7000rpm = 135 mph

Mk1 1.8 at 7000rpm = 142 mph

Australian only market have a 3.63:1 diff ratio in the 2001 6 speed mx5 with limited slip diff. The part number of the 3.63 ring and pinion is MA0227110 or USA;M002-27-110A. ?

Standard 1.6 clutch lasts longer under boosted power but the 1.8 soon gives up – upgrade for 1.6 is to use 1.8 flywheel which allows a larger diameter friction disc with aftermarket clutch.

Late ‘92/3 had a 23 tooth red speedo gear as opposed to the 20 tooth in 90/92

"Top Gear TV did a piece on Zero Tolerance of speeding a few months back and tested some mechanical speedos. They found that mechanical speedos consistently under-recorded speeds below about 25 mph and consistently over-recorded speeds above about 50 mph. The error was about 10 percent, ie 20 mph on the speedo meant 22mph on the road." Peter Easterfield

"If the thunk, thunk, thunk rate was around 6-7 times per second, then it's likely to be side shaft related (probably a CV joint). If it was 25-30 times a second then it's likely to be front shaft related
(probably a U-joint)." Ray Ayala

I broke 4^th gear gears – the 5^th gear is actually an overdrive while 4^th is continuously driving the layshaft. This made more noise in 4^th while it was quieter in other gears due to the load on the gears rather than just rotating the layshaft in neutral in 4^th.

Mk1 MX5 Gearbox weighs 80 pounds, can also go UPS

"TII rear and a TT tranny using a Miata auto bellhousing. Not a pure bolt in but close enough for anyone with access to a fab shop". Randy where TT=93-95 RX-7 Twin Turbo = FD3S

"american tranny would certainly be cheaper - the reason I recommended the TT tranny is because it keeps the parts in the Mazda family and the TT has a mount for a PPF on the tailshaft (albeit a different one). A 88-89 929 5-speed 'R' tranny also has a "boinger" bellhousing which could also be adapted and the TT tailshaft could be bolted on, but it is as rare a hen teeth and unlikely you'll find one easily." Randy

"From what I understand Rick is running a 3rd gen RX7 Tranny on an Automatic Miata Bell housing. How much work is entaled in doing this, what work is needed = A RX-7 TT tranny, Miata auto bellhousing, RX-7 TT/TII, NA auto driveshaft, custom clutch disk with 215mm diameter and 1"/23 spline shaft + some fabrication.

Can you use a Miata PPF = Needs to be modified. The PPF attachment point is not the same as the Miata's

Do you need a custom driveshaft? = Yes. The trans yok is bigger. Need TT,TII, or auto 2nd gen NA RX-7 yok.

The Miata auto bellhousing also needs to be drilled for the TT/TII/929/B2600 trans ('R') too. The 'R' trans is also larger in diameter than the Miata 'M' trans so there may be some BFH work on the tunnel too. Rick is the one to really ask since he did it.

Check these threads out:

"Randy

"FWIW, I measured a BW World Class T-56 a while back and it would fit with out any real problems.... Other than your need to fabricate a bell housing, and a PPF adapter or torque tube. Oh, and the shift lever would be about 7" father to the rear than on a normal Miata. (Remember that cool shift turret we have? There's a reason for it.)" Eric Vaillancourt

The unconfirmed rumor…

"As most all of you know Mazda made three rear ends, 6", 7" and 8". Well there was also a limited run of rears made for the rear of the B2600 and B2200 4X4 trucks and it used a 7.5" ring gear. It is a hybrid rear as the pinion gear shaft is identical to the 7" and the front pinion housing is the same too so it bolts to the 7" rear housing. The only question I am still working on is will the larger diameter ring gear fit inside the Miata/RX-7 rear aluminum housing and whether the axles are the same spline/diameter. The ratios available are 4.10 in the RWD B2600, 4.44 on the B2200 4X4, 4.625 on the rear of the NZ Kia Sportage and and 4.778 on the rear of the US Kia Sportage. The Sportage has an optional clutch type LSD. If anyone has easy access to a junkyard check the axle shaft diameter and splines." Randy

I have tried the Brainstorm shifter and the KG works shifter. The Brainstorm just shortens the stock lever without raising the fulcrum. You could do the same thing by just lopping an inch off of your shift lever and re-threading it. I also tried the KG works Shifter. It raises the fulcrum and shortens the lever. Very short sift throws. Also raises the shift effort and increases the notchiness of the shifter. I am now running the stock shifter with a Voodoo Pearl Magnum knob. Works for me. If you like the shift effort of the Miata and don't want an increase in notchiness or effort, then just leave it alone, or shorten the stock shifter about 1/2 to 1 inch. Jess

Mk2 5spd into Mk1

Detail differences, shifter will not interchange because now one pin (they can be made to by removing extra pin) , reverse/neutral switches on different side.

"I had issues with the '99 gearbox I put into my '92 last year. I had to reuse my old neutral, reverse and speedo parts, 'cause the new ones had different connectors, or in the speedo case the new one was electric instead of the mechanical that I needed. I drove the second pin out of the shifter turret and sealed the hole - no issues after that, the original shifter worked fine... " Todd Paciorek

speedo gear part of this thread (the original topic), the mystery speedo gear part number is "M533-17-400A". This is specifically for the 6-speed transmission with the 3.636 rear (to get the correct speedometer reading). The part number for the ring and pinion gear set itself is "MA02-27-110" (you'll find this on Randy's web site). Ed Cheal

"We do a conversion kit for RX7 to standard Toyota Supra gearbox, which is

good for up to 350 - 400HP. If the torque isn't too great and the car is

relatively light then it should stand up. However a better option would be the R154 Big Supra gearbox. It is good for up to 500 - 600 HP 10kg heavier.

Conversion kit & gearbox standard Supra NZ$ 4920.00

Conversion kit & gearbox R154 Big Supra NZ$ 7940.00

Prices incl air freight to nearest International airport.

Both kits incl a performance clutch." Regards Colin Dray