drive line vib

[Lawrie]

I have been chasing a drive line vibration in my 33 for 14 years,
Once I got it to do about 3000klms as smooth as ,then the other month I had the rear end out to clean it up and paint it and on refitting it the vibe was back,it comes in after about 30 -60 miles,and is just as you get off the gas,like on the float,
it changes as the car goes over undulations on the road as the rear end goes up and down.
Stop for lunch or coffee and its right for another 30 or so miles,
Now, I have replaced every thing in the drive line,from engine mounts,pilot bearing,new clutch,balanced engine ( that is as smooth as)gearbox bearings,throw out bearings,quite a few NOS universals,(all balanced)roller bearing in the front of the torque tube to get the up/down play to .006,new and ballanced drive shaft,splined coupling,all new rear end bearings ,wheel bearings, tyres,balanced wheels,spring shackles,etc.

This time I have found one thing that I think may be the cause.
The retainer for the gearbox mainshaft bearing, B 7085, is spigoted over the rear bearing and bolted to the rear of the gearbox,and the B 4513 cap u/joint housing inner fits onto it via the 4 x B 5098 bolts,
These bolts are all that locate B4513 cap(and driveshaft) to keep it on the centre line of the mainshaft and bearing,thus keeping the driveshaft true to it via the u/joint.
If these bolts are loose or worn,or the B 7085 has worn holes where these bolts locate,then the B4513 can move up or down depending on how front of the torque tube sitting when you slide them together before you tighten the B 5098 bolts.
On the checking the one on my spares ,I see there is a fair amount of movement on these parts.all up about .030 up and down movement of the B5413 cap.
I plan to set the box up on my mill and bolt the B 7085 to it,then fit the cap B4513, true it up concentric to the gearbox mainshaft,then ream the holes and make new larger B 4098 bolts.
This will keep it true .
I will be doing a 14000klm trip in August so will have to have it sorted by then.
Lawrie

[Pete]

Probably wouldn't hurt to put a couple of 1/4 inch dowel pins in to guarantee zero each time it is assembled.

[Ross F-1]

I don't doubt that it's a good idea to do as you say (with dowels), but I'm not seeing how temperature would affect the alignment? I'm assuming heating up from running is what is happening.

[Lawrie]

I am thinking it has to do with the lube thinning in the driveshaft roller or u/joint.
But I,m open to suggestions,
Lawrie

[Kpar]

I can lend you a 33 for the trip to WA just sort out my problems on the way.ha ha.

[G.M.]

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Try a low melt point chassis grease in the U joint. I have seen this problem before. Thin oil and low on grease as well as high temperature grease will do this. With high temperature grease the U joint cuts a hole in the grease and runs dry inside of the hole. Low temperature grease melts as it gets warm and sags down to the bottom and is dipped by the U joint. G.M.

[keith oh]

John Deere corn head grease is a low temp grease available at, where else, John Deere dealers. Also is good for water pump lube.

[Lawrie]

Funny, My 28 A has done around 80000klms on the same U/joint,only ever grease via the fitting on the u/j housing,and its as smooth as .
But the 33 has tried me out,I have the JD corn head grease and will try that again on reassembly,I also have a little tank on the firewall that I can fill with gear oil and it is connected to the fitting on the U/J housing via a tap that I can turn on,this I can use to drop some oil into the u/j cavity when travelling.
BUT, this is only a band aid ,as Ford would not have made it to need a fix like that.
I also found that if you put too much grease in the U/J cavity it ends up in the gearbox.
Lawrie

[Lawrie]

An update on the driveline .
I fitted the U/joint cover to the back of the transmission and made up a jig to fit on the mainshaft and run a dial indicator around the bell ,supriseingly it was not out of round but with the old worn bolts and holes was .029 out of concentricity with the gearbox mainshaft
I used smaller bolts and set it up to run true,then set it up on the mill and drilled and reamed two holes to .500, then made and fitted my new bolts and then did the other two holes,on reassembly using the new spigoted bolts in the now .500 holes , the runout now is less than .001.
The bolts I made should be nice and tough,as they are machined from an old Model A driveshaft
Lawrie

[Tom Walker]

Nice engineering Lawrie!

[Terry,OH]

You can change the diameter of the bolts through the inner U-joint housing and the cast iron bearing retainer but I believe you have to stay with the same thread diameter so the nuts can pass the outer housing and tighten. From your photo above I believe this is what you have done. This could also be done with sleeves using the original style bolts. I have found many loose U-joint cover nuts.

[Pete]

Originally Posted by Lawrie

An update on the driveline .
I fitted the U/joint cover to the back of the transmission and made up a jig to fit on the mainshaft and run a dial indicator around the bell ,supriseingly it was not out of round but with the old worn bolts and holes was .029 out of concentricity with the gearbox mainshaft
I used smaller bolts and set it up to run true,then set it up on the mill and drilled and reamed two holes to .500, then made and fitted my new bolts and then did the other two holes,on reassembly using the new spigoted bolts in the now .500 holes , the runout now is less than .001.
The bolts I made should be nice and tough,as they are machined from an old Model A driveshaft
Lawrie

Good show guvner, by jove.