Diff slack?

[KM]

Its a Tr4a with CV joints on the rear axle. There is no slack in the prop or the drive shafts. There is however some slack in the diff but I don't know whether this is normal or not. The attached pic shows the angle one wheel goes through with prop locked and the other wheel on the ground. See the two chalk marks.

When driving between power on and brake on or visa versa it feels like the slack is excessive.

Can anyone tell me this is normal or not?

[glang]

Id say normal - theres got to be some backlash in gears and in a diff its the sum of play in various gears....

[Hogie]

Hi Kevin,

there is a maximum amount of back lash on the crown wheel when being built.

By the time this gets to the road wheels it is significantly more.

Rather than worry about the lash do you get any clonking when taking up the drive or chaning gears in general.

I do not consider your amount of back lash a problem.

 

Roger

[KM]

Roger, yes I do. If the power has been on and I brake you can feel the drive train go from one end of the slack to the other making smooth driving tricky. Probably more noticeable after braking then accelerating.

I have CV joints on the driveshafts so it isn't a UV issue. The prop shaft has no slack in it so it isn't the UV joints there.

[glang]

CV joints can have play as well although I think theyre less prone to wear than U/Js.... Also of course the gearbox gears have their own play which adds to the rest of the drive train.

However I think the problem is more likely to be in the rear suspension - I dont know the TR design but is it possible theres play somewhere in the location of the back axle assembly?

[RobPearce]

TR4A is the same setup as TR5/6 and the big saloons & Stag. Plenty of scope for play in the semi-trailing arm bushes. I'm not familiar with how those are anchored, though, on the chassis. With the saloons, there's also bushes between the subframe and the floor.

[iggy]

my 2500 saloon had the same problem with no slack in drive shafts or prop new uj's all round new poly bushs on trailing arms and diff mount, replaced the bevel and thrust washers in the diff chris witor sells these washers in various sizes,

[KM]

The trailing arms are off to replace the bushes.On the left side the bushes were nicely centred but on the right side they are offset. Am I going to have a tracking issue if the right hand side has centrally positioned bushes? Also what is suitable lubrication to help insert new bushes? Normal grease? Will this affect the bushes long term? Rubber ones.

[iggy]

Fit all the new bush's centrally should be ok then,

[thescrapman]

I used red rubber grease on mine, both rubber and poly.

you will need it!

you will also need the special tool to fit them. Bit of thick walled pipe and a length of studding, some big washers ( I think I used Herald body mount ones) and nuts.

[KM]

Thanks Gavin & Colin. Will update in a while. Lots of degreasing and painting to do first.

[KM]

Its all back together and runs fine. Thanks for all the advice.

One last question. How tight should the nylocs holding the diff on be? Since they are nylocs I guess there is no torque setting so perhaps so many threads visible?

[glang]

Glad to hear it's resolved with no expensive diff or CV joint work required. On the Herald those diff holding nuts just do up until you get to the end of the thread on the studs so not related to their torque. However don't know yours is the same....