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Gearbox

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K

Kelly

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Just finished a gearbox rebuild on my 70"s Midget. The box needed new syncros, 2nd and 3rd gear. The rebuild was straight forward until all was reinstalled and road tested. It will not stay in 3rd gear. I can hold it in, but under acceleration or if the shift lever is not held it will pop out.

I can not fully ingage 3rd gear. 1st, 2dn, and 4th, work ok.

All gears engaged ok on the bench test.

Could this be a result of replacing 3rd gear?

I know I have to pull it back out, does anyone have a suggestion on what to look for when I get the side cover back off?
 
Hi Kelly,
Did you check the engagement dogs on the sliding collar that engages third gear? Mine were pretty chipped from a similar issue. Another issue I had was with play in the lay gear bearings allowing the lay gear to rock and spit it out of gear.
 
Thanks for the advice guys.
I should add that the gearbox shifted (stayed in each gear) before I took it apart. The rebuild was done because regardless or gear selected it would grind. Downshifting could only be accomplished by double clutching.
When I got the box apart the syncro rings were worn out along with the 2nd and 3rd gear syncro cones.
I got the rebuild kit (bearings, gaskets, lay gear shaft, ect) along with the gears and reassembled.

I keep thinking that the main shaft (3rd motion) rear bearing position is suspect.
When I first installed the rear bearing I pressed it all the way to the shoulder. When I installed the main shaft the gears did not line up with the lay shaft. Also the main shaft did not appear to fit all the way into the input shaft (1st motion).
I took the main shaft out and brought the bearing up a bit, reinstalled and the gears seem to line up better.

Does anyone know the correct procedure for installing the rear bearing on the main shaft?
 
I really can't help you here, but if you obtained your parts from mixed sources, you may want to doublecheck their specs.

I am not an expert,so I can't recall the details of this conversation, but during a discussion with my mechanic at Brooklands in Tacoma about a month ago, he expressed some frustration with gearbox parts obtained from Moss because there was key info that is NOT explained in the Moss catalog on partnering these with other specific Moss gearbox parts due to non-standard dimensions on one or the other.

I wish I could be more specific, sorry man... but you could try calling Matt at Brooklands in Tacoma, Wa for an interesting conversation on the topic of gearbox troubleshooting!
 
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