Strengthening The Rear Prop

[Denis K]

I will be running a c20xe redtop on throttle bodies with mild cams in my Manta which will be a road car.

It will also have a gripper lsd and steel torque tube.

I see on risse motorsports website that they do a strenghtened rear prop for the manta.

Is there any need for this or will the standard rear prop be ok with the 200bhp approx that I will be running??

[Retro Power]

standard rear prop will be fine with 200hp. Sheared one clean off with 425hp though

The bit you want to look at is the rubber mounts on the front of the torque tube, add another bobbin to tighten it up a bit

[Autocrosser]

Sorry to jump in on someone else's tread but what power can safely be put through a manta axle? The one in my car has a quaife ATB diff, steel torque tube with extra end bobbin and a 4.75:1 ratio. I'm planning on putting an xe in which has been dyno'd at 210bhp on carbs and basic ignition and I'm planning to up the power with throttle bodies and management but there's little point if the axle can't take it. Car will also be running 8" moulded slicks.

[Retro Power]

Its not really a precise figure. Certainly they will stand 300hp without an immediate, complete failure, BUT, the pinion shaft bearings are the weak point, and the life of these is reduced at higher power levels (they wear badly with standard power).

If you are happy with a replacement of bearings and diff reset every year or two then you will be fine. I'd guess that won't be a problem on a competition car, and you'll prob want to check and maybe replace the diff plates that often anyway if its used a lot.

[Retro Power]

ps I have never ever seen a halfshaft failure in one, have seen a few dead crownwheel and pinions, but these were almost certainly down to dead pinion bearings causing excessive clearance and poor contact patch on the gears.

[Autocrosser]

Thanks for that its put my mind at rest certainly the axle will be overhauled as its not been used for 12 years. I'm hoping the ATB diff will give the half shafts and drive train less stress than a plate type diff as there not as violent and they never really lock like a 90% diff.

[Retro Power]

sorry didn't pay attention, didn't see atb, hence comment re. plates!

Will be ok though as long as its rebuilt, then keep an ear on it. If it starts to whine, get new pinion and carrier bearings in it sooner than later that way your 4.75cwp will stay good, they are not cheap!

[Autocrosser]

Could the pinion bearing failure be down to the raised nose on the diff caused by the torque tube system? Reason I ask is that usually when setting say an escort axle the nose usually points down when the cars at standstill (keeping said bearing oiled during normal driving) and making the driveline straight during hard acceleration

[Retro Power]

fair question, and I've got no idea I'm afraid! These axles do run a slightly higher oil level than some, maybe to compensate, but I have no idea really!

[Autocrosser]

Thanks for the info about the axle I'll just have to keep it well serviced. Wether lack of oil causes the problem matters not as its impossible to change the diff angle anyway.

Cheers Craig

[hesus2003]

standard rear prop will be fine with 200hp. Sheared one clean off with 425hp though

The bit you want to look at is the rubber mounts on the front of the torque tube, add another bobbin to tighten it up a bit

have ya any pictures of fitting another bobbin?

[lamchop77]

Autocrosser

Escorts and mk1/2 cortinas usually run a diffangle of 4 deg not parallel to the road so they are nose up. Autograss cars with live axles on the rear used to run the nose pointing down so that when the cars were accelarating the drivetrain lined up with the gearbox tailshaft. I checked to see where the oil was in the diff and the bottom of the bearing was sat in oil on the grasser with the std axle fitted

You could drop the nose of the manta axle by moving the mountings up on the front crossmember that holds the donut. Did this on the grasser when i ran a std axle but it was easy as the chevette/kadett front mount was easily packed with custom thick washers. Dont know if it made a massive difference, ended up witha sierra back end which was miles better!!!

Chris

[Retro Power]

standard rear prop will be fine with 200hp. Sheared one clean off with 425hp though

The bit you want to look at is the rubber mounts on the front of the torque tube, add another bobbin to tighten it up a bit

have ya any pictures of fitting another bobbin?

afraid not, but its not tricky, just drill another hole in the torque tube in the same front to rear plane as the others, and a matching one in the housing, then put another bobbin in there (exhaust bobbins of a suitable size work well)