3 replies to this topic

[1963MKI]

Ive got my Austin 1300 gt close ratio box that I'm currently rebuilding. Im trying to reshim the main shaft bearing. My question is, the bearing has been drifted into the box with its retaining clip. But when I tighten the bearing retainer to just the bite point. Im left with zero clearance between the bearing retainer and the casing, and also zero clearance between the bearing retainer ridge and the bearing face (when measured through the diff casing.) So if I understand correctly the ridge on the inside of the bearing retainer pushes against the bearing face to apply preload. If theres a gap between the casing and the retainer, too much pre load is applied so you shim it to get adequate amounts. But I seem to have the opposite problem, the retainer is meeting the casing before it meets the bearing, so theres no preload being applied really. Its as if I need to shim the face of the bearing, not the casing?

 

 

 

 

[Spider]

The Manual - from memory here - says that there should be + or - 0.001" here, so, according to that, the Bearing C Clip can be 'unloaded'.

 

That's what the Factory say, however,,,, I have to say, I've always disagreed with it, as when left with clearance, the Bearing can (and will) float back and forth wearing the Tunnel in the Case. I've found from hard learned experience, everything possible needs to be done to anchor that bearing firmly in place, so when I assemble these, it's Bearing Mount Loctite and rarely do I fit any shims, preferring to have the Retainer Plate lock the Bearing tight.

 

I have done a few Gearboxes that have been like yours. Unlikely that this is an issue in the era that case was made, but I'd suggest checking the should to shoulder distance between the Register for the Mainshaft Bearing to the 1st Motion Shaft Bearing. This needs to be 7.400 to 7.404" If it's less, what I've done here is make a shim that fits between the Mainshaft Bearing C Clip and the Register in the Case, if it's a Synchro Gearset, this measurement is critical. If that's in order, then try a couple of different Retainer Plates, if that doesn't get you out of gaol, then you could have the Retainer Plate Machined on it's outer face to give you more depth there, or, put a bead of weld around it on the inner and have that ground back. I wouldn't think it wise to try a shim here as it'll likely be quite thin and as it wouldn't be captive on it's ID, it might walk out.

[gaspen]

The Manual - from memory here - says that there should be + or - 0.001" here, so, according to that, the Bearing C Clip can be 'unloaded'.

 

That's what the Factory say, however,,,, I have to say, I've always disagreed with it, as when left with clearance, the Bearing can (and will) float back and forth wearing the Tunnel in the Case. I've found from hard learned experience, everything possible needs to be done to anchor that bearing firmly in place, so when I assemble these, it's Bearing Mount Loctite and rarely do I fit any shims, preferring to have the Retainer Plate lock the Bearing tight.

 

I have done a few Gearboxes that have been like yours. Unlikely that this is an issue in the era that case was made, but I'd suggest checking the should to shoulder distance between the Register for the Mainshaft Bearing to the 1st Motion Shaft Bearing. This needs to be 7.400 to 7.404" If it's less, what I've done here is make a shim that fits between the Mainshaft Bearing C Clip and the Register in the Case, if it's a Synchro Gearset, this measurement is critical. If that's in order, then try a couple of different Retainer Plates, if that doesn't get you out of gaol, then you could have the Retainer Plate Machined on it's outer face to give you more depth there, or, put a bead of weld around it on the inner and have that ground back. I wouldn't think it wise to try a shim here as it'll likely be quite thin and as it wouldn't be captive on it's ID, it might walk out.

 

Which Loctite do you use for glue the bearing ? Loctite 603 or 638 seems similar but can't decide which one is suit

[Spider]

Which Loctite do you use for glue the bearing ? Loctite 603 or 638 seems similar but can't decide which one is suit

 

 

I'd have to check to be sure but I think it's 641. I've used a few and they all seem good - just a medium strength bearing mount is all you need, don't go for a super strength or anything crazy like that - it'll only make it harder to get apart later.