Lost 4th gear in my spitfire

[Robert Beaulieu]

Hi while recently running my vintage 1300 cc spitfire at NHMS, after a few laps, I could feel thetransmission tightening up.
by the second qualifying, after two laps, I lost the ability to shift into fourth gear....double clutching did not help as well

fortunately, I needed fourth only for a brief section of the straight, so soldered on...

I was wondering if I was overheating my fluids, to have the classic symptons (old incompatible fluid) but, interesting, on my cool down lap, with the revs lower, I shifted right into fourth, almost kills that idea.. the fluid would not cool down in that length of time?.

This car is registered for the street as well, and have not experienced any problem with normal driving..

Has anyone had any experience that sounds like this....

My problem, is I want re duplicate the problem, then try to resolve, before towing 400 miles to the Glen, and experiencing the same problem,

much obliged to any input, thanks


r

 

[Tom Broring]

You will probably have to pull and teardown the box to know what is going on. You did not mention if it is a Spit or GT6 box and whether it has the early 3 rail shifter or later single rail shifter. The 3 rail shifter has a number of linkage bushings that need to be in good shape.

I would check 3 things from your description.
First, the layshaft on later boxes has a number of cageless needle bearings that can cause wear and damage to the layshaft at high RPM. If the bearings/layshaft are eating themselves up this can slow bown the speed of the layshaft faster that the rest of the box causing difficult shiting.

I would also check the caged needle bearing that fits inside the rear of the input shaft. This bearing goes between the mainshaft and input shaft and keeps them aligned under load. If that bearing goes bad it can wear into the main shaft allowing the two shafts to flail around at high RPM.

Last, the hub for 3rd/4th that engages the syncros will sometime get wear or minor damage to the splines it slides on from racing abuse. I like to take the detents out of the hub and check that they move smoothly and touch up with a small file if needed. Problems with that movement can get worse with heat.

You should be using GL 4 fluid or Redline MT90.

Good luck. You will probably need 4th at the Glen.

 

[Matt Blehm]

Completely unrelated to spitfire, but my old FWD daily driver had a bad input shaft bearing. the cage on the ball bearing came apart and chunks of the cage got caught at the bottom of the shifter linkage, preventing me from shifting into certain gears. (Most of the time, it would lock me out of 1-2 when I was stopped at a light. No fun starting off in 3rd with a high-strung no-torque engine!)

As soon as I'd get rolling, the gears turning was enough to cause the oil flow to wash the bits away from the shifter and I'd be able to shift again for a while. Then when I stopped at a light again, they'd settle in the bottom of the box again and block the linkage. Before I fixed it, I just got used to double-clutching down into 1st at 30mph when I was slowing for a light.

http://blehmco.com/pics/car/drivetrain/ ... 001405.JPG
http://blehmco.com/pics/car/drivetrain/ ... 001406.JPG
http://blehmco.com/pics/car/drivetrain/ ... 001410.JPG
http://blehmco.com/pics/car/drivetrain/ ... 001411.JPG

I'd definitely look at the issues Tom brought up, but thought I'd mention this as an unrelated "why cant' I get the thing into gear sometimes" comment... you never know who it might help.