Easy-ish to fix, though, as it's an RWD. You'd just pick a different rear differential ratio to sort it out.
- Thread starter Alister
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Easy-ish to fix, though, as it's an RWD. You'd just pick a different rear differential ratio to sort it out.
My immediate reaction is have a look in VW Passats and Audi A4s and see if they have a separate bellhousing.
Inline engine in those, so anything there is likely to be a closer match than the A3\Golf line. If it's an integral bellhousing, you could look to use that as the basis for machining into a separate part?
There's definitely vw -> T5 and Ford Type 9 bellhousings available, perhaps one of those is a starting point?
Inline engine in those, so anything there is likely to be a closer match than the A3\Golf line. If it's an integral bellhousing, you could look to use that as the basis for machining into a separate part?
There's definitely vw -> T5 and Ford Type 9 bellhousings available, perhaps one of those is a starting point?
Sorry for not replying to the posts, Been away for a few days.
Thanks Norm, getting rid of the dual mass flywheel was always going to part of the project anyway, I believe it is a fairly common conversion. If you are talking to him I'd appreciate any input he might have.
Funny I mentioned the possible issue of the engine revving less than the rotary and my son (with his mechanical engineering degree) said I was talking nonsense, but I'm glad to see someone else agrees with me. Not sure it will matter too much though as the the difference in red line is only around 1000rpm so I guess it will be quick off the mark. :-) It might help that ours is a six speed so probably has a higher top gear. In the end I guess the RX8 wouldn't have been revving all that high at 70 so it just means the VAG lump will just have to match it.
I think all of the A4's and Passat's with in-line engines are 4wd but never thought of them having separate bell housing, defo worth a look,
I think SR20's have been used for a similar conversion but the Turbo ones are less common and more expensive than the VAG lump. We got ours (complete with Audi A3 in reasonable nick) for £550 so after flogging what's left I'm hoping it will only have cost us a couple of hundred quid.
Thanks Norm, getting rid of the dual mass flywheel was always going to part of the project anyway, I believe it is a fairly common conversion. If you are talking to him I'd appreciate any input he might have.
Funny I mentioned the possible issue of the engine revving less than the rotary and my son (with his mechanical engineering degree) said I was talking nonsense, but I'm glad to see someone else agrees with me. Not sure it will matter too much though as the the difference in red line is only around 1000rpm so I guess it will be quick off the mark. :-) It might help that ours is a six speed so probably has a higher top gear. In the end I guess the RX8 wouldn't have been revving all that high at 70 so it just means the VAG lump will just have to match it.
I think all of the A4's and Passat's with in-line engines are 4wd but never thought of them having separate bell housing, defo worth a look,
I think SR20's have been used for a similar conversion but the Turbo ones are less common and more expensive than the VAG lump. We got ours (complete with Audi A3 in reasonable nick) for £550 so after flogging what's left I'm hoping it will only have cost us a couple of hundred quid.
two things
1. make sure the rx8 engine and vag engine rotate in the same direction. I knew someone put another engine in a Honda S800, finished the conversion, started it and found he had 4 reverse gears and one forward
2. sometimes you get lucky, we have just mated a Lexus V8 to a land rover gearbox and found the PCD centres were on the same spacingso we were able to have a land rover flywheel machined to take the lexus starter ring and do it that way
Errr, Mmmmm, Will have to check that as must admit it hadn't occurred to me. Maybe the boy has already thought of it.
dan.taylor.1
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Nope, all A4/Passats from like 2000 onwards and some before are inline in 2wd and 4wd formats. Owning an A4 myself and having worked on a few. However I'm not certain the 2wd ones can be made into rwd as there is a blanking cap and no idea if the output shaft goes back same as a 4wd one. however I have seen 4wd boxes with the front shafts blanked and diff welded/fixed so they're rwd.
rtbcomp
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Just keep it locked in 4WD, with the centre diff locked (if fitted).
dan.taylor.1
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The diff locking on my A4 is automatic and brake based, don't ask me how it works, as mechanically minded as I am (also a qualified mechanic!) I have never sat down and worked it out! There is no mechanical lock, at least on the VAG's.
I can confess how good the Torsen 4wd system is though, I've never got stuck, or lost control, and it sticks like glue in the dry and wet.
Dan
I can confess how good the Torsen 4wd system is though, I've never got stuck, or lost control, and it sticks like glue in the dry and wet.
Dan
If we can keep the Mazda gearbox it means the rest of the drive chain stays the same.
If we change the gearbox we will have to change the drive shaft and have it made to fit the Mazda diff. The Mazda one is carbon fibre so can't be modified (not shortened anyway). We would also have to check the gearstick is in the right position and may not be able to locate the engine as we want to. That might cause other problems as there isn't much room.
If we change the gearbox we will have to change the drive shaft and have it made to fit the Mazda diff. The Mazda one is carbon fibre so can't be modified (not shortened anyway). We would also have to check the gearstick is in the right position and may not be able to locate the engine as we want to. That might cause other problems as there isn't much room.
simplysimon
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these guys seem to have overcome the transmission/clutch problem with a Honda Civic Vtec powered RX8 which is probably a good match to the Mazda gearbox as Vtec engines need revving to get the power out of it.
http://www.racingforum.pl/RX-8-VTEC-k20-by-Przema72-t105452.html
http://www.racingforum.pl/RX-8-VTEC-k20-by-Przema72-t105452.html
normspanners
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Where did 4wd come into the equation, mazda rx8 are rwd as far as I know the gear box is too far back to make it 4wd????
VAG don't make rear wheel drive passats but they do make 4wd. If we want to use a VAG gearbox for the conversion it Will have to be the 4wd one with the front bits disconnected. I don't think we Will do it that way though as although it will ease one issue it will cause several more.
PhillipM
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Stop listening to the TDi owners down the pub.
As many have said, just use a clutch plate with the Mazda spline in it.
Nice idea but unfortunately won't fit.
simplysimon
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It would be a bit optimistic to think you could just use an 'off the shelf' clutch kit without moding either the friction plate or the gearbox input shaft somewhere.
you will also need to know if there any discrepancy between the front of the gearbox bell housing and the running face of thrust bearing when its in the operational position or you could find you don't have enough travel on the clutch pedal for the thrust bearing to reach the pressure plate spring fingers, of course it could well turn out that the thrust bearing runs constantly on the pressure plate if it too close.
but these are just engineering problems that can be over come in a machine shop, I would have thought your biggest issue will be getting the Volkswagen ECU to communicate with the Mazda dashboard and SRS system
you will also need to know if there any discrepancy between the front of the gearbox bell housing and the running face of thrust bearing when its in the operational position or you could find you don't have enough travel on the clutch pedal for the thrust bearing to reach the pressure plate spring fingers, of course it could well turn out that the thrust bearing runs constantly on the pressure plate if it too close.
but these are just engineering problems that can be over come in a machine shop, I would have thought your biggest issue will be getting the Volkswagen ECU to communicate with the Mazda dashboard and SRS system
The Mazda clutch is completely different size and shape to the VAG one so not really do-able.
I am checking out different companies to see if they can make a new flywheel for us. Others have done the same conversion so I am checking with them, I agree the measurements are critical to get a working clutch.
The Mazda is Canbus and the dash is digital so there is no way the VAG ECU will talk to it. There is a guy who claims he can supply a kit to make the Mazda dash work, http://www.canbusauto.co.uk. I have been in touch with him and he thinks should be no problem.
simplysimon
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could you cut the centres out and weld the VAG one into the Mazda one?, not sure what the torsional stresses will be on the construction of the hybrid flywheel it will depend on the materials of the donor parts. is your Mazda flywheel cast iron with a centre nut?
you may have to mod an after market lightened chromemolly flywheel like this one and you will probably have to have it ground and balanced just to be safe
what about the gearbox main shaft support bearing that's located in the end of the crank? does the Mazda needle bearing fit the Audi crank
you may have to mod an after market lightened chromemolly flywheel like this one and you will probably have to have it ground and balanced just to be safe
what about the gearbox main shaft support bearing that's located in the end of the crank? does the Mazda needle bearing fit the Audi crank
The VAG one is Dual Mass so totally different shape and a good bit smaller, plus shaft sizes are different as are teeth sizes. In any case it will be revolving at up to 7000rpm so must be perfectly balanced. Not really something I can do at home. I think it is best to get one made.
