Can’t be right… Is there supposed to be a thrust washer on the mainshaft between reverse and the bearing? I got the thrust washer properly on the layshaft with the correct end float, but that shouldn’t matter to the mainshaft. I can’t see anything in the parts book that would relate to this…
Hello John,
No Thrust washer. Not that leaving a Synchro Baulk Ring out will cause your issue, but have you got all four in place?
About the only thing that will give you the result that you have is for the rear bearing not to be fully home in the Gearbox Housing and the Main Shaft not pulled as far to the rear as possible, through the rear bearing. Before you have the Extension Housing (2+2), or Oil Pump/Speedo Drive Housing (S1 to S2 TSC and DHC) in place, complete with all components up to and including the Companion Flange Nut, you have to draw the Main Shaft back through the Rear Bearing with suitable spacers and the Companion Flange Nut, whilst ensuring that the Rear Bearing is fully seated in the Gearbox Housing.
Thanks for the reply, thayt makes sense. The rear bearing is fully seated, but I need help figuring out how to draw the mainshaft back. Also, if I do that won’t the synchro on 4th gear be loose - it’s the one between the constant pinion shaft and the mainshaft gears… all I’ll be doing is moving the gap around…
Hello John,
I see that your car is an S1 OTS, therefore it will have a short Oil Pump/Speedo Drive Housing and short length of Mainshaft protruding through the rear bearing. Use a combination of the Companion Flange and whatever spacers you can cobble up that will make contact with the inner race of the rear bearing only. I have a set of purpose made spacers that I use where the Companion Flange is not required and draw the Mainshaft through the rear bearing using a nut and the thread of the shaft.
When the Mainshaft is drawn through the Rear Bearing as far as it can go, that is with the hub of the Reverse Gear in contact with the inner reace of the Rear Bearing, then as long as you have all the Gear and Synchro components assembled correctly, all will be correct.
When you removed the Mainshaft assembly from the Gearbox Housing, you should have had a Radiator Hose Clamp secured to the Mainshaft close to the rear face of the Reverse Gear hub. This was to ensure that all the components on the Mainshaft were held compacted so that the assembly would fit through the opening at the top of the housing. The Hose Clamp in place simulates the Rear Bearing being pressed fully home and I’m sure you would not have seen 4th Gear Synchro Hub being loose. The Synchro Baulk Ring will be loose, but that is normal.
I hate to tell you this but were it my transmission, I would take it apart and get the mainshaft out. It appears something is stopping the rear bearing from closing up all the free play. In the past I have bought new bearings and found them to be out of spec with either their circlip placement or their inside or outside diameters.
Hello Dennis,
The correct bearing is not available, period, But that’s another story. The pictures below show the two sides of the correct, original bearing, with practically no radius between the face and bore of the inner race, at the circlip end of the bearing.
If the bearings John has are other than Chinese, or Korean manufacture, then they are likely to be in tolerance. The bore is an interference fit on the shaft and my comprehension of John’s fitting procedure, is that he has not used any means of pulling the shaft through the bore of the bearing and has merely pressed the bearing into the back face of the Gearbox Housing and in doing so, pushed the Mainshaft forward. With the gears on the Mainshaft interfering with the Lay Shaft Cluster to some extent, they tend to stay where they are when the Mainshaft goes forward, thus creating space between the Mainshaft components and exposing the short needle rollers as shown in his pictures. Its a common trap for new players.
By using the Companion Flange and suitable spacers to draw the Mainshaft through the bearing using the Companion nut and washer, he will quickly find out if the bearing is correct and is going to go on, as there should be no geat amount of force required to tighten the nut. If the bearing he has are Chinese origin, then yes, I would remove the bearing and compare it’s bore dimension with the original bearing. The bearings sold by the usual Jag Part suppliers are typically Chinese, in my experience, with the rear bearing having a corner radious on the back face of the inner race similar to that shown in the picture Side Two. Such a bearing provides an infinitisimal bearing surface for the Oil Pump drive, which is driven by friction only. It works in the short term, but this minimal bearing surface soon compacts on the face of the Oil Pump Drive and begins to slip. Evidence of slippage can be seen on the face of the inner race in picture Side One and this bearing has everything going for it.
Thanks for all the information Bill, I appreciate your time and expertise.
As you say, I have made no attempt to draw the mainshaft forward, manual doesn’t mention it so I didn’t do it. I am also still puzzled by that strategy, since if I pull the shaft forward, the gap will move to between the CPS and mainshaft, ie between fourth gear and the synchro hub, and seems like the synchro ring would be loose. Both front and rear bearings are firmly seated against the circlips so if there’s a gap it has to go somewhere.
Anyway, I bought both front and rear bearings from a usual, and the front is a KSM, made in Japan. The rear, as I recall, came in a plastic bag without manufacturer shown and there is nothing on the face of the bearing to tell me its provenance. Looks like I need to remove the whole thing and look the bearing over carefully.
Hello John,
You don’t draw it forward, you have to draw it through the rear bearing and to do so, you need to draw the Mainshaft to the rear. What has happened thus far is that you have seated the rear bearing in the housing by pressing/driving it towards the front and if you don’t pull the Mainshaft to the rear through the rear bearing at the same time, then it will move forward giving your current issue.
There are a lot of things that are omitted, or poorly explained in the manual.
KSM are good and are the closest you will get with regards to the bearing surface for the Oil Pump drive.
Normally I would have a Gearbox in the process of being restored, so to be able to take pictures for you. I will in a week, if you’re in no hurry.
Hello John,
That can’t happen. 3rd Gear and the 3rd/4th Synchro Hub are all forward of an integral collar of the Main Shaft, all being held in place by a large nut at the front end of the Main Shaft. You can position the Main Shaft anywhere you like and there will be no separation of the components forward of the integral collar. If you have the front nut in place and tight, then its impossible for 3rd Gear and the 3rd/4th Gear Synchro Hub to separate. Only the 4th Gear Baulk Ring can be loose and be displaced if the Main Shaft is in place to the rear and the First Motion Shaft and Front Bearing assembly is not fully home toward the rear.
Bill, I finally have the mainshaft back out to examine the bearing. It was a very tight fit in the case and no room to “tap” it out, so I had to rig something between the reverse gear and the bearing to press it out.
Anyway, the new bearing’s dimensions are the same as the old one, maybe a couple thou more on the outside diameter, hence the difficulty removing it. The circlip is in the same place. The chamfers are different as you pointed out with a chamfer on the circlip side that is not present on the old bearing. Are you using these bearings? Are they adequate to drive the oil pump?
So I am back to re-assembling and moving the mainshaft forward to close the gap between 2nd and 3rd or at reverse. This will move the gap to between 4th and the synchro hub and result in a loose synchro ring. Does this create any problems with GB functioning? Does the gearbox work normally when the ring is loose?
If you have a picture of the “suitable spacers” you use with the flange and nut then that would help. I can envision something but a few clues would make it faster…
Hello John,
With regards to your comment relating to the 4th gear baulk ring, the synchro hub assembles from the front of a shoulder on the Main Shaft and therefore is excluded from any end play infuelnced by the position of the Rear Bearing and the Main Shaft, except if the whole assembly is not far enough forward then the Baulk Ring will be loose because of the resulting gap between the First Motion Shaft and the 4th Gear Synchro Hub. However, if the Rear Bearing is fully home in the Gearbox Housing and the Main Shaft is pulled back in the bore of the Rear Bearing inner race, all will be OK.
I use KSM Bearings as they have the greatest bearing area interface with the oil pump drive compared to any other bearing I’ve inspected. There is plenty of evidence of slippage with the original, correct bearing, so its important that the Companion Flange Nut be torqued up correctly. I’ll take pictures of the inner race of the bearing I use so you can be sure what you’re using is the same.
If you can wait until early in the coming week, I’ll take pictures of what I use to pull the Main Shaft back into the Rear Bearing.
When installing the Rear Bearing, you have to simultaneously pull the Main Shaft back through the bore of the Rear Bearing and move the bearing forward into the bore of the Gearbox Housing. I have a fixture plate that spans both the inner and outer race of the bearing that allows the bearing to be pushed forward and with the aid of the Companion Flange Nut and spacers, pull the Main Shaft back though the bearing.
You can tap the Rear Beaing into the Gearbox Housing as you pull the Main Shaft back through the bearing, but you have to take care that you don’t brinell the bearing races. A disk with an OD slightly smaller than the Bearing OD and a Bore that allows it to be assembled onto the Main Shaft ahead of the spacers being used to aid in pulling the Main Shaft back through the Bearing will circumvent any chance of brinelling the bearing.
Bill, I got this working. I used a piece of 1 1/4" galvanized pipe 1 5/8" long as a spacer between the flange and the bearing and used a long bar to move the mainshaft.
Everything is now tightened up in the GB, the bearings are both properly seated and the gears work smoothly. Thanks for your help, I could not have done it without you!!
