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TF Gearbox Washer/Circlip question

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Jeffrey711 Jeffrey M
Buffalo, NY, USA   USA
Hi All, I'm rebuilding my MG TF gearbox following the Barrie Jones Gearbox video, MG Workshop manual and others. I've come across a question regarding the circlip, washer, and 1st/2nd sliding hub on the main shaft.

In the attached photo the area circled in red shows a gap of about 0.07" between the sliding hub and the circlip. Apparently this can create problems in the gearbox and so modifications have been recommended.

From the Barrie Jones MG Gearbox rebuild video he suggests modifying the setup and putting a shim or washer in that gap. However, others on the mg experience suggest that the washer or shim should go on the other side of the circlip, that is, between the circlip and the washer for the center bearing. I put two red arrows in the picture, wondering where the shim should go. Any thoughts are appreciated.

Thanks,

-jeff

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Attachments:
MG circlip.jpg    53 KB
MG circlip.jpg

GB3 George B
Winter Haven, USA   USA
The lower shim/spacer positions the mainshaft fore and aft . The upper arrow location takes up slack and moves/locates the 1/2 hub. The most important thing is the shift fork has to sit passively and be centered in the groove after assembly. No idea how to check this without assembling everything. George

Declan Burns Avatar
Duesseldorf, NRW, Germany   DEU
Jeff,
I made a comment on this issue here recently
https://www.mgexp.com/phorum/read.php?46,3880893
Regards
Declan

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buscar Avatar
buscar Silver Member Carlo Busato
Canberra, ACT, Australia   AUS
1953 MG TD
I found getting an old bearing and sanding the inner and outer mating surfaces so you can slide the shaft in and out and measure the gap without having to press(or hammer) the bearing in and out of the gearbox every time was a help.

Declan Burns Avatar
Duesseldorf, NRW, Germany   DEU
That's what I do for differentials- I made set-up bearings using a flap wheel on a set of old bearings-always a good idea.
Regards
Declan

In reply to # 3884631 by buscar I found getting an old bearing and sanding the inner and outer mating surfaces so you can slide the shaft in and out and measure the gap without having to press(or hammer) the bearing in and out of the gearbox every time was a help.

Jeffrey711 Jeffrey M
Buffalo, NY, USA   USA
Thanks for pointing out the thread, very helpful! Sorry I missed it in my original search.

-jeff

Henley Graeme Hogg
Godalming, Surrey, UK   GBR
1953 MG TD
I am currently rebuilding my TD gearbox. IMHO, excessive clearance between the 1st/2nd sliding hub and the mainshaft circlip would, in the first instance, suggest worn 2nd gear yellow metal synchro rings and for which the best option would be to replace. I agree there should not be pressure on the selector fork when in neutral. If 2nd gear engages smoothly and it doesn't try to slip out of gear then the 1st/2nd sliding hub end float could be considered acceptable. Accepted that selector fork to striking dog running clearance should be within tolerance. Shimming between the circlip and the mainshaft bearing would similarly be an attempt to overcome worn 4th gear synchro rings and the same reasoning would apply. Hope this helps.

Lonnie Cook Avatar
Orlando, FL, USA   USA
See this thread by Keith Meyer going on at the same time as this thread.
https://www.mgexp.com/phorum/read.php?46,3880893

Spacer / shim not needed between circlip and 1-2 hub.

My TF gearbox has the same gap. New hub.

Lonnie
TF7211



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Attachments:
Clearance-1stGearToWasher.jpg    45.5 KB
Clearance-1stGearToWasher.jpg

55-60MG4KM Avatar
55-60MG4KM Silver Member Keith Meyer
Corvallis, OR, USA   USA
I have communicated with 6 knowledgable people on this subject and I keep getting conflicting information. I now have 4 votes for: Yes, install a spacer and 2 Votes for No, dont bother with the spacer. So, I asked and received an email from John Twist on this subject. His answer was also: Yes, install a spacer. Plus he offered that the reason to install it was to keep the inner hub from moving so far on the mainshaft that the ball bearings might pop out to far and prevent the outer hub from sliding forward when you enter second gear. He commented that the spacers he has seen are commonly not as thick as a quarter dollar (I miked one at .0675"winking smiley but thicker than .025". He also reccomended not to use a material that is to soft as it will eventually be beaten thin by the repeated stikes of the inner hub. Although my gearbox didnt have one (but someone was messing around it it previously) I'm going to install the spacer.

I have a gap of .043". Barrie Jones says you should have a gap of .004-.006". I think that is pretty tight and I'm going to look for something with a thickness that gives me a gap larger than that. Maybe around .030 - .032". I bought a 1.185" x 1.75" x 18 guage (.049"winking smiley machine bushing that is pretty hard. I have been trying to file it, sand it, reduce its thickness but I can't keep it consistently flat across the diameter of bushing. Might have to take a new one to the machine shop and have them grind it down to my preferred thickness.

Oh, by the way of rebuilding, I replaced all my hub / synchro ring pieces and one mating gear. I found out that I should have lapped in the synchros to the new and old gears I installed. Time to back up and redo!

I'll post this on my original string that Declan mentions above.

Keith

Jeffrey711 Jeffrey M
Buffalo, NY, USA   USA
Keith, thanks for your input. Note zoro.com offers "Arbor Shims" that should work. There's a pull down menu on the webpage where you can select inner diameter (ID), outer diameter (OD) and thickness. I see they have a 1.125" ID, 1.625" OD, 0.031" thickness which may work for you. FWIW, I'm going without a spacer and will see how the gearbox shifts etc.

Good luck.

-jeff

55-60MG4KM Avatar
55-60MG4KM Silver Member Keith Meyer
Corvallis, OR, USA   USA
Jeff: Thanks for the shim info. As an FYI, this morning I woke up to an addition to my orginal string question on this subject as referenced by Lonnie & Declan above. It was from Barrie Jones who stated that in his review of gap shown in the pictures I posted and the measurements presented that a spacer is NOT required. So, in less than 24 hours I now have another No response but this one is from the person who started me questioning the gap in the first place. I have made a 180 degree turn and am NOT going to install a spacer. To much thinkin and not enough doin. Keith

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