Transmission woes

PostPost by: prezoom » Thu May 07, 2009 3:36 am

While trying to figure out why my transmission is jumping out of 4th gear, I noticed that the 3rd/4th shift rail was positioned so as the shift fork put a slight pressure on the 3rd gear side of the collar when the transmission was in 4th gear, and held in position by the detents. Having purchased another transmission for spares, I decided to compare the shift fork position on that one as compared to the one that came with the car. It was very apparent the spare located the shift fork almost directly in the center of the collar when in the 4th gear position. Comparing the two shift rails, detected a slight difference between the location of the hole where the grub screw locates the 4th gear fork and the 3rd gear detent. Checking both of the parts manuals I have, show only one shift rail for both the early and late transmissions. Has anyone encountered this difference? For the moment, I will be fitting the shift rail from the spare, in hopes relieving the pressure on the shift fork on the 3rd gear side of the collar will keep the transmission in top gear. Also the detent springs were out of spec, measuring short of the specified proud length, and perhaps not putting enough pressure of the detent balls. As an aside, I cut short a tour because of the transmission dificulties. On the 350 mile trip home, I discovered if I kept the rpm above 4200 in 4th, it wouldn't jump out of gear. Drop below those revs and out it would come. Hard to keep the revs up in top gear on a Monday morning in Los Angeles traffic. Strange.

Thanks for any thoughts, guidance or help.

Rob Walker
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1964 Sabra GT
1964 Elva Mk4T Coupe (awaiting restoration)
1965 Ford Falcon Ranchero, 302,AOD,9",rack and pinion,disc,etc,etc,etc
1954 Nash Healey LeMans Coupe

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PostPost by: rgh0 » Thu May 07, 2009 7:04 am

HI Rob

It sounds like you are going down the right path. I know of no reason for differences in change rod length between the detent and fork grub screw hole but that does not mean it has not varied. Ther should certainly be no pressure on the fork when in gear. WHile the box is open I would check for bearing play as worn bearings can cause movement resulting in the box jumping out of gear also.

cheers
Rohan
Last edited by rgh0 on Thu May 07, 2009 12:22 pm, edited 1 time in total.
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PostPost by: prloz » Thu May 07, 2009 10:52 am

Hi Rob,
I have seen two types of shift rail for these transmissions. The detents in the rail are a different depth.
Regards,
Peter.
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PostPost by: garyeanderson » Thu May 07, 2009 12:13 pm

I did some looking and found two pair of shift rails, these were the "last to be used" type, but too good to toss in the event of a real problem. I noticed at the time that one pair had some shallow detents cut but I didn't notice much else.
The two sets are marked with red and green, reverse is on the right, the one/two rails in the center and on the left are the three/four rails. I didn't see any part numbers on them but I didn't look all that hard.

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PostPost by: prezoom » Thu May 07, 2009 3:29 pm

Thanks for the help. For a while, I thought I was going crazy. After posting, in noticed another anomaly. When I changed out the 3rd/4th rail, I noticed the area where the shift lever resides in the rails is now a bit offset with the 1/2 rail. Could make things a bit notchy. Going to pull the 1/2 rail out of the spare and see how it lines up. The transmission came with the car when I bought it. Purportedly it was a rebuilt box and by the looks of the syncros, they appear quite new. Since getting the car up and running I have only put on about 6,000 miles in the past two years

A couple of other things. The old shift lever was junk, bent wrong and I believe too short, so I decided to make a new one out of the anti-sizzle one from the spare. Does anyone have the measurement from the bend in the shaft to the point where the threads for the shift knob begin? Would like to keep the length close to original. Also, which is the better shift lever retaining cup, the nylon one or the steel one? I have both and have been using the steel one. If I should change, now is the time.

Rob Walker
26-4889
Rob Walker
26-4889
50-0315N
1964 Sabra GT
1964 Elva Mk4T Coupe (awaiting restoration)
1965 Ford Falcon Ranchero, 302,AOD,9",rack and pinion,disc,etc,etc,etc
1954 Nash Healey LeMans Coupe

Owning a Lotus will get you off the couch
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PostPost by: garyeanderson » Thu May 07, 2009 5:08 pm

Shifter caps,
non-integral remote,
twin cam and early direct shift Cortina (i think)
and integral remote
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non integral remote shift on top,
integral remote center
and twin cam shifter cap below.
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more info about gearboxes and shifters
elan-f15/magnesium-aluminium-gearbox-bits-t17587.html?hilit=%20shifter
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PostPost by: prloz » Mon May 11, 2009 2:13 pm

Hi Rob,
Distance from bend in shaft to start of threads is 3 7/8"
Think I would use the later nylon retaining cup.
Regards,
Peter.
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PostPost by: prezoom » Mon May 11, 2009 3:23 pm

Thanks Peter. Waiting for the exhaust manifold gaskets to arrive, then I'll see if the new rail and shift fork make the difference. My new lever is almost an one inch longer than you describe. I think I'll see if I like the new length and if the throw is too long, it will be easy to shorten.

Rob Walker
26-4889
Rob Walker
26-4889
50-0315N
1964 Sabra GT
1964 Elva Mk4T Coupe (awaiting restoration)
1965 Ford Falcon Ranchero, 302,AOD,9",rack and pinion,disc,etc,etc,etc
1954 Nash Healey LeMans Coupe

Owning a Lotus will get you off the couch
prezoom
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PostPost by: garyeanderson » Mon May 11, 2009 3:37 pm

I believe that Peter has the right dimension, this is one of the replica's that we made. The bend is something like 23 degrees, some how I managed to add some rotation towards the left (I forget if it was done intentionally or not). I believe this is the first one made and the pattern was one of the original S2 shifters. The other two that were made were a copy of this one...

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