Ital/Marina axle Max torque & BHP

[GasMan]

Can any of you engineer types tell me what My axle can cope with? I have a JW factory approved Fireblade and am getting the engined tuned over the winter. The axle is modified , a baffled and overfilled variety. Bearing in mind my car wieghs in at 380kg and I use very soft ACB10's what should I limit the power to? Reliability is paramount.

 

Thanks Matt.

[GasMan]

I should add it is the disc braked variety and I believe this has some bearing on the half shaft durability??

Matt

[Robster]

Your axle should be fine to 160bhp...although if you have an LSD, it'll cope with a lot more. You will hear a lot of pundits telling you 150 is the limit..but the reality is that oil surge will kill the axle..not the power. The half shafts may break under a lot of heavy shock loading and a lot of power, but you can get uprated ones from Quaiffe. The open diff is not bullet proof, but an LSD is.

 

The oil surge really is the thing to be careful of, overfilling helps, but myself and a couple of other people have now fitted oil seals over the baffles, preventing oil from surging over the baffles and effectively sealing it in the middle of the diff where it is needed. If you are going to do a lot of track work, I would strongly recommend this.

[GasMan]

Thanks Robster

I do have an LSd , but I don't know if I have oil seals fitted over the baffles. I guess I should ask Steve Perks of SPC as he built up the axle.

Matthew

[MarcNS]

After getting diff whine at Donington I asked what to do and now

fill the axle nearly full through the breather and have added over 250m of

Molyslip.

Not sure if this is the best combination but the whine is under control, so I am now tempted to go for a bit more power 😬

 

Marc

 

The CarThe Club Built

Vvvrrrooomm

[Robster]

Unfortunately, if your diff whines, you have worn the CWP. Filling the diff nearly full is just asking for oil to come out of the ends and weep onto your brake shoes..the oil seals will be overcome. It is hard cornering with hot, thin oil that kills them, the CWP is under full load at a time that there is no oil on it (it will have sloshed over the baffles which then prevent it running back into the centre of the diff), so you end up running around the track with diff arms full of oil and very little where it's needed.

 

I would suggest that you run the diff as you are Marc but empty it, refill to the level plug, plus another 750 ml ish (no more though for the reasons above) and see if it is fine.

 

Incidentally, sprints don't seem to hurt these diffs so much, because it is the repeated cornering on the tracks that is the killer, you have enough oil for the odd slop over the baffles not to hurt, and it may not heat up as much. Oil will slowly seep back from the baffles, but it will take minutes, not milliseconds! by which time you are another lap or two around Brand's!

[elie boone]

I have found that the backlash on the original axle is often out of tolerancealso due to rather high tolerances.

Get the Backlash within tolerance is absolutely critical to prevent the CWP to give up