I remember "Hy-Tac" from the old days - there were two versions - one in a tin like "normal" grease and also a spray version in an aerosol. I seem to recall the spray type was a orangey brown colour. It first came to light with the 66 service info and was carried over for the 300.

I also recall, on the 66 a little wedge kit used to cure rattles from the prop (it didn't work).

Mac.

Followed by this:

RE: The problem with weighty aftermarket props. Jonovlov was talking to me the other week about modifying an RX8 or MX5 prop (they are carbon fibre and about the right length) to fit. They're light, strong and can cope with power. Possible solution? I'll have access to one over the next few days so I might do some measurements.

MX5 props made of carbon?? Pics or it ain't true!Excellent if it is though. A couple of companies make custom carbon props, might be worth looking into since reco-prop seem to charge the earth.

RX8 does though:

http://en.wikipedia.org/wiki/Mazda_RX-8

"The manual gearbox model uses a carbon fiber composite driveshaft to reduce the rotational mass (moment of inertia) connected to the engine..."

Ahh, thats a shame as it was an MX5 I was looking at todayt. I might look at the MX5 ones as well as they weigh basically nothing. Think they're alloy. I'll try and find an RX8 in a scrapyard

pettaw wrote:Any custom prop manufacturer would have to understand that the prop spins at engine RPM, and therefore has to be properly balanced and light enough so that its not putting too high an inertial mass onto the input shaft of the gearbox.

Thats the problem Andy, that's not the only problem here. 95% of the time, yes, the prop will be spinning faster than the equivalent in a front mounted gearbox car. However, there is one case where that isn't true, that being the case of switching in overdrive (assuming the car in question has one, but seeing the standard comparison I make to Fake is a Dolomite Sprint it jumped out).

In that case, the "normal" prop is doing more rpm's than the 300 prop, at much higher torque loadings (as the torque multiplier, the gearbox, has already happened). However, it's not going to have to fight the synchros at any point in it's life, so the inertia doesn't matter, infact pales into insignificance when you are going along the motorway as its directly coupled to the wheels which have 1ton of car doing 70 on top of them.

Volvo solved the problem with the 360, I'm convinced we are looking at a situation of "torque tube or go home", it solves the low inertia and the alignment all in one sexy package rather than having to be reliant on engine and gearbox mounts being both statically and dynamically stable.

-

Presumably a replacement design of prop with the shaft made of something which exerts a similarly small moment (either large diameter in ally (i.e. standard) or CF, or small diameter in steel (a la 360)), and the rubber "wobble joints" replaced with something more robust but not massively heavy (small CVs? compact steel UJs?), plus more robust splines.

Stupid thought, but what about an expanding prop with a slide joint, so you don't have to put in in bent? On the other hand, If you used something as small diameter as a 360 prop, there would be almost no bending...or if you used something with compact UJs (how much torque can ones the size of a steering shaft UJ take?), they would bend down out of the way, allowing a solid spline section to be slotted in square.

Although the torque tube arrangement is surely superior (mainly because it's found attached to a superior engine ), it's a lot of work, and there is a finite supply of donor cars...and there *is* an argument which says they're better off staying where they are There must be a middle ground between a TT swap and putting in a heifer of a conventional large-diameter tubular steel prop with large UJs, etc. Chris and Mac undoubtedly make excellent points re: synchro wear. Excellent thinking, gentlemen!

cheers

James

Some great ideas and point coming from this thread.

The torque tube asper the 360 is probably the best solution but with a improved clamping method in an ideal world would be the best way to go. The trouble with that is a lot of parts would need to be manufactured to produce a new unit. There are only so many 360's that could donate parts. As a 1 off then it is a option for you are comited to the project.

Whatever you replace the prop with the weight needs to be kept as close to the centre of rotation. As Mac and others have pointed out you would be adding a lot of stress to the synchros. Using the 240 rubber couplings is something I had considered before but they are too big in diamter.

The Vibration from the Reco Prop is curious, How much is down to the length and how much is down to soggy engine mounts I don't know. The other thing to consider with the reco prop is that is has no give for back and forward movement and that is likely to cause vibration and aditional stress on the clamped joints.

I've got some ideas on what can be made to make a simple system that should work and be a lot stronger than the original setup.

classicswede wrote:The trouble with that is a lot of parts would need to be manufactured to produce a new unit. There are only so many 360's that could donate parts. As a 1 off then it is a option for you are comited to the project.

Only three custom parts need to be made from measurements taken and initial drawings made. However, the parts are not something simple that I can machine, nor any of my "fred in an shed" mates, it's going to be a proper engineering shop unless I can make my home made spark eroder work a bit better. I'm currently expecting ~£600 in the cost of these three parts alone. I agree, it's probably not the way forward for everyone and as Foggy says, at this point, it makes more sense to put that money into building a good N/A redblock. My issue as ever is not only am I building for the F7R, but also the B18FT sat on the drive.

I look forward to seeing your ideas Dai

When i looked into using the torque tube it was less than 3 parts to make.
I reckon it could be done for less than £600.
a Cut and shut bellhousing, half 360 half 340 1.7, a vauxhall centre plate for the clutch, 360 clutch fork and bearing, 360 clutch cable, and a modifed rear gearbox mount.
Its more than doable, if i would of kept my F7R and not gone the mad T5 route i am now im sure the car would still be on the road with this setup.
Adam