MG-Cars.info

Welcome to our Site for MG, Triumph and Austin-Healey Car Information.

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG TD TF 1500 - Springs for 1-2 Hub, TF Gearbox

> Should the ends of the springs for the balls in the 1-2 sliding hub of my TF gearbox be flat on top?

> Should I use the original springs for the hub instead of using Moss replacements?

The spring on the left in the photo below is an original spring from a 1-2 hub The ends appear to be ground flat so that it contacts the ball in the hub uniformly. I can see grinding marks on the spring. Springs from another 1-2 hub that I have are also flat.

The two springs on the right are replacements from Moss. The ends were not ground flat and will probably not contact the ball uniformly(?) The one in the middle is as it was received from Moss. I tried to relieve the rought edge of the cut of the spring on the right side of the photo with a sharpening stone -- not much difference.

The replacement springs are also longer than the originals.

My untrained eye didn't notice anything wrong with the twelve original springs that I have from two 1-2 sliding hubs. I just thought that I would throw some more money at my gearbox rebuild!!

I haven't tried to assemble the gear/hub with the new springs yet.

Thanks for your help,

Lonnie
TF7211

LM Cook

Lonnie,
I would not think it will make that much difference.
This is just for location purposes. The ball is the thing that will drop into the locating depression and the spring just gives it some force to help it stay there and hold that position.
There are several springs right? Around the 1-2nd gear hub? Seating on the actual ball is possibly not that important.
If the original were ground flat I would put that down to just good engineering back in the day and was done before they were heat treated to make them springs. Grinding them after the fact may reduce the springs hardness. (The Heat) Also change their length.
It should be fine to use them as is.

[Did you read the write up on how to peen the balls in the hub? :) So they don't fly all over the place next time its undone.]

Just my 2 C's Worth.
Rod


R. D. Jones

Rod -

Thanks. I didn't think about them being ground flat before they were heat treated. I'll play with both types of springs and decide which to use.

Yes, I read how to peen the six balls into the sliding hub. But after so many starts and stops in my gearbox rebuild, I'll avoid starting another task that I may screw up.

I have a tool to help slide first gear over the hub. Tried it this morning ... it works. I packed the holes in the hub with Lucas Red Tacky Lube so the balls and springs didn't go flying into the ozone if I slipped.

The used hub that I am using is solid ... it doesn't have the groove cut in the center of it. It should hold up better than two others that I have with the groove.

Lonnie
TF7211
LM Cook

Lonnie,

I am no gearbox expert but have rebuilt a few T-Type gearboxes. As I see it, the stronger (or longer) the six springs in each hub ... the more force needed on the gear-lever to compress them when pushing into gear. That extra force is relayed to the synchro' cones and so might make the synchro' work better. I always stretch the springs a SMALL amount. I have been tempted, but have not been game, to stretch them a lot (or fit stronger springs). Although I think that should improve the synchro', it might make it too hard to engage gears and I don't want to risk having to pull the gearbox again.

I wonder if some gearbox specialists have tried this sort of thing and know how far to go with the stretching / strengthening! Perhaps ask a few of them for an opinion? Do you have any local specialists? Sorry for the late response .... I have been away again.

Bob Schapel
R L Schapel

Bob -

I will start assembling my gearbox tomorrow. I have three used 1-2 sliding hubs ... two original ones and one nice looking "improved" hub with no grove around it where the balls and springs go. I will use the "improved" hub. I'll try the new longer springs and the old springs to see if I can fell any difference when I assemble them. Although it would be a good experiment, I doubt that I will assemble the gearbox with one set of springs, then disassemble and try the same gear and hub with the other springs.

Two Questions:

1) Do you think that the balls rotate somewhat when the hub is sliding? The new springs have a rough-cut edge that could prevent the balls from moving or could score them.

2) All three sliding hubs can wobble a tiny amount inside first gear when the balls and springs are not in place. What amount of movement is acceptable? I am installing a new layshaft, laygear, and first gear. Don't want to damage them by using a worn hub, but also I am just about out of cash and time buying parts for this rebuild.

Lonnie
TF7211
LM Cook

Hi Lonnie,

I have never seen an "improved" hub. I can only guess that it gives more spline contact inside first gear because there is no groove. I would think the amount of "wobble" is the important thing. Lots of wobble would indicate a higher degree of wear. If the hubs all have a similar amount of movement inside the gear, then that amount is probably OK. I don't think they wear much in that area. Do check the fit of the sliding hub on the mainshaft also. I think that is more likely to be an area that wears.

I don't know how much the balls rotate. I would imagine they do rotate a bit, but probably not in a smooth consistent manner. I agree with your concern re the balls seating nicely on the springs. You could stretch the old springs to match the length of the new ones, or take the sharp edges off the new ones. Either tactic should be OK.

When putting in the new laygear, try to get the end-float right. The thrust washers can wear a bit, resulting in too much end float. From memory it should be about 4 thou' but do check that figure. To measure it, you will need to do a "dummy" fit of the laygear (needles and all) to measure the float with a feeler gauge. If the float is 10 thou too much, you will need a thrust washer 10 thou thicker at one end. Sorry, I don't know how much tolerance is allowable and I can only guess the symptoms of excessive end-float. Good luck with the rebuild!

Bob Schapel
R L Schapel

This thread was discussed between 16/07/2015 and 20/07/2015

MG TD TF 1500 index

This thread is from the archives. Join the live MG TD TF 1500 BBS now