mgb back axle

ppyvabw · Post by **ppyvabw** » Sun Jan 07, 2007 5:28 pm

I haven't been on forum since it changed. I bust my back axle while ago burning it up down the A1. It spat its oil out of a hole in the diff cover. It was whining badly. I Dad has since rebuilt the axle. I think he will have done it OK, measuring backlash and preload correctly, he tends to get things right, except the sod is still whining. Not as bad as before but certainly load enough to annoy me. Its had all new bearings and new gears.

I have put some additive in the oil, molyslip or suminc. That was useless I may as well have filled it full of jam.

Any suggestions. Its a load noise and its quite difficult to tell where it comes from, but it seems to come from the back. Dont think its the gearbox. Its in good condition and was full of oil unlike the axle.

Prop shaft joints dont make this noise do they? There is no play in either of them.

Any help

ian.stewart · Post by **ian.stewart** » Sun Jan 07, 2007 6:10 pm

TBH, any noise from any bearing or gearset is not good, putting a oil addative in the axle will nor cure the problem, only disguise it, untill the reason for the noise is found and cured, the longevity of the axle is compromised, any marking on the gears will reprcipricate its self throughout the gears, this is because the gears are designed with a "hunting tooth" so wear is spread evenly amongst the gear teeth, so any damage is also spread around the set, and the pinion will wear 3-4 times faster than the crownwheel once face damage has occoured.
Ian

ppyvabw · Post by **ppyvabw** » Sun Jan 07, 2007 6:14 pm

well it didnt even disguise it. mmmm, all gears, bearings are new and set up correctly. It has only done 600 miles. Is there a chance it will go quite once run in some more.

ian.stewart · Post by **ian.stewart** » Sun Jan 07, 2007 7:00 pm

ppyvabw wrote:well it didnt even disguise it. mmmm, all gears, bearings are new and set up correctly. It has only done 600 miles. Is there a chance it will go quite once run in some more.

I would be VERY surprised if the noise went away, , I used to set big CWPs up for boats, and we scrapped a few gearsets if they were noisy on the test rig, not because they were faulty, but they had been run incorectly set, god bless Loyds Shipping, kept me in O/T on a regular basis
Not saying that you have scrapped your gears yet, but it dosent take long to kill a set of gears that are slightly miss set.

davemgb · Post by **davemgb** » Sun Jan 07, 2007 10:44 pm

Did you fit new bearings to the half shafts?

Dave

ppyvabw · Post by **ppyvabw** » Mon Jan 08, 2007 7:50 am

Yep. Looked at the old teeth. They were totally buggered badly scored and needed changing so that was £200 somethin quid. New carrier bearings, new pinion bearings, new wheel/halfshaft bearings, new thrust washers, new planet wheel shaft. Dad put it toghether whilst I was at uni he usually gets stuff right. He sprayed engineers blue on gears or suminc (actually black spray paint) to get pinion in right place, and then measured back lash with dial gauge. cant remember what he set it to but it was a figure he got off the net somewhere or maybe from moss, cant remember. Couldn't get the right sized spacers for the diff carrier so he made shim to go under the carrier bearing, on the carrier to move it over to left and then made do with what spacers we could get. Preload on bearing set to about 3 tho, i think. Pinion tigtened up until play in pinion went and then a bit more. No torque figure anywhere and couldn't get on new forum.

It was quiet to start off with and then got loud again which is why i suspect perhaps the prop shaft joint has maybe got a damaged rollar or something making a noise because I greased the propshaft after putting it together again and after 20 miles after it worked the grease out it got noisy again. Prop shafts dont normally make that noise and there was no play in it though

JC. · Post by **JC.** » Sun Jan 14, 2007 5:01 pm

Would this be a V8 CW+P set?
The 3.07:1 veriety or is it an 1800 gearset 3.9:1

Reason I ask, is that there have been reports that some of the new manufactured V8 CW+P sets whine a lot.
Clive wheatly does some good gearsets. 'Bout £325 though.

What sort of axle have you got? V8 axle, C axle, converted 1800 B axle shortened Sd1 axle, other?

ppyvabw · Post by **ppyvabw** » Sun Jan 14, 2007 9:04 pm

No its the 1800 CW+P. I have massive wheels on mine and I liked it as it was so I stayed with it. mmmmm, At 90 to 100 mph at light loading, it has started to vibrate and rumble. This is the first time ive done 100 since rebuit it so it be just the way it is. Its a standard MGB Tube axle connected to an Larger prop joint by way of an adaptor.

mgbv8 · Post by **mgbv8** » Tue Jan 16, 2007 7:39 pm

If you have a modified prop-shaft, are you still using the MGB front end, ie, the telescopic bit.
I'm just wondering if the prop is too long and trying to push the pinion shaft back into the diff when you go over bumps?
Just a thought.
It's a shame you are a long way away. I have a spare MGB 1800 axle that I dont need anymore, but its in Kent. I was going to do it up but have changed my plans.

ppyvabw · Post by **ppyvabw** » Tue Jan 16, 2007 11:21 pm

nah, its rover flanges and telescopic bit. Measured up and let the guy who made the prop work out the rest. Well, replacing axle looks like only option but I have brackets and stuff welded on to my axle for panard rod, anti tramp bars etc. Its a pain. Or maybe ile just put independant suspension on it!!

Hope its not gearbox. Its difficult to locate the noise

JC. · Post by **JC.** » Sun Jan 28, 2007 5:24 pm

When you say you have "massive wheels" what size are we talking inc tyre size?

ppyvabw · Post by **ppyvabw** » Sun Jan 28, 2007 10:16 pm

225/60/15 so not really huge on 8 inch rims

JC. · Post by **JC.** » Mon Jan 29, 2007 2:42 am

This is quite interesting.
I am currently midway through my own V8 conversion. However, being a university student I don't exactly have the cash to throw at a factory axle unfortunately. This means I am forced into keeping the 3.9 diff short term.

The wheel and tyre set up I have is an identical rolling radius to yourself, all be it with 6.5J rim width. (I am assuming you have sebring arches to get 8J wheels in???)

Anyhow, can you tell me what the car is like at motorway speeds? i.e at 70mph is it a reasonable environment to be in or is it unpleasent?
Should you want to play in the outside lane with the BMW's do you feel you have enough grunt left to pull out at 70mph?

Appologies for the vague questions. I have yet to find ANYONE who wanted to keep the 3.9 axle. Having never driven a V8 MGB at speed I do not know what to expect?

Thanks in advance,

JC.

ppyvabw · Post by **ppyvabw** » Mon Jan 29, 2007 8:23 am

Ha ha. Im a uni student as well.

It will cruise at 80 at 3500 revs, 100 at about 4000 revs. I'll be honest though its not very pleasant at high speeds for long distances tho, its quite fatigueing. Can touch 60 in 2nd and 90+ in 3rd.

Dont worry, mines a 3.5 and theres still plenty left at 70 to play with BMWs

I have indeed got sebring arches. I dont think it was because the axle wasn't strong enough that broke it, its more because it ran out of oil through a rusty hole in the diff cover.

JC. · Post by **JC.** » Mon Jan 29, 2007 9:31 am

Another nutter @ uni!

Excelent stuff.
You'll have to bring it down to the pod some time.
The specs of mine are not that impressive to be honest.
P6 v8 (although the heads will be some fancy SD1 items that mgbv8 is sorting out for me)
Induction - Webber dcoe on a swan neck
LT77 from Roger Parkers V8 roadster
Exhaust - custom twin pipe system

Got the engine out of it last week. Even with no engine or box it sits lower than a 76GT on standard suspension.