ADVICE NEEDED - 1964 4.2 Series 1 E-type that has a problem engaging in reverse once hot.

[Raymondo]

I have a 1964 4.2 Series 1 E-type that has a problem engaging in reverse once hot.

A typical example would be that I would reverse the car out of the garage, say first thing in the morning (cold), whereby the reverse gear would be found effortlessly. I would then drive for a few miles, come to a halt with engine running and reverse, and at this stage, the reverse gear would engage first time only at best, 3 or four times out of five trial attempts, and that the one or two times that it failed to connect whilst palming to the left, usually they slotted in on the second or third attempt.....still no major problem at this point. However if I continued to drive on for a further twenty or thirty miles and then tried to reverse park into a hotel car-park, then it would fail to do so 10 out of 10 attempts. The only course of action then being to drive home into the garage. whereupon, the following day, say first thing in the morning, the car (cold) may easily be reversed out of the garage with the greatest of ease as if there was no problem.

I have tried changing the gear box oil, all to no avail.

Please can anyone advise.

[1954Etype]

Sounds like the reverse detent needs adjusting. Not a big problem.

[abowie]

Another trick is to shift into first gear before going into reverse, all with the clutch in. Apologies if you already know this.

[Doug Buchan]

Hello Raymondo,
Early synchro hubs are known to be troublesome and were later modified by the factory.
Check out the gearbox offerings from Denis Welch Motorsport...

https://www.bighealey.co.uk/jaguar/jagu ... box?page=2

Regards,
Doug

[Raymondo]

Thank you all for your replies - most helpful. I will update you once fixed. Thanks again for your time taken replying to my query.

[Gerry]

Hi Raymondo,does the clutch biting point change when the car gets well warmed up?Reverse being the only gear without syncro is more likely to have engagement problems if the clutch is dragging slightly?Can be aggravated even more if the idle speed creeps up as well.

Regards Gerry 62 ots.

[angelw]

Raymondo wrote:

the reverse gear would engage first time only at best, 3 or four times out of five trial attempts, and that the one or two times that it failed to connect whilst palming to the left, usually they slotted in on the second or third attempt.

Hello Raymondo,
In what way is Reverse Gear failing to engage? Is it that with the gear change lever palmed to the left, you simply can't then move it to the rear to select Reverse Gear.

The clutch dragging would result in a notchy gear change to Reverse, at best, and grating gears if you simply can't engage Reverse because of the Reverse Idler Gear is rotating. I believe you would have mentioned this had it been the case; accordingly, I think you can eliminate the clutch as an issue.

There remains only a few things that would resist Reverse Gear being selected and most are associated with the Gearbox Top Cover, the easiest to resolve as the Top Cover can be removed with the Gearbox in situ.

The only picture I have to hand of the Reverse Selector mechanism (at the Gear Lever level) until I go to the workshop, is the one following.



This shows the Reverse Gear Selector Rod in the Reverse Gear Selected position. Neutral is when the two vertical Red lines are aligned. When in the Neutral position, the end of the Gear Change Lever is able to move sideways within the bounds of the Selector Rod Engagement Slot and is inhibited from inadvertently engaging with the Reverse Gear Selector Rod by a spring loaded plunger (Reverse Indent Plunger). When Reverse Gear is to be selected, the end of the Gear Change Lever pushes the plunger to the Right, compressing the spring inside and engages with the slot in the Reverse Gear Selector Rod. There is a spring loaded ball bearing inline with the Bolt and Lock-nut shown in the picture, this puts load on the side of the plunger and locates in an annular groove of the plunger when Neutral, or a Forward Gear is selected. Too much pressure could make moving the plunger with the end of the Gear Change Lever difficult.

As a first step in finding what is causing your issue, I would remove the Centre Console and the transmission tunnel cover so that you can view the Gear Change Lever selector mechanism. When reverse gear become difficult to engage, observe if the end of the Gear Change Lever is actually pushing the plunger far enough to the Right to engage with the Reverse Selector Rod and only the Reverse Selector Rod. If it is, then you can rule out the Reverse Selector Plunger as the cause.

If the cause can't be traced to the Reverse Indent Plunger, I would remove the Gearbox Top Cover and observe the movement of the Selector Rods, using the Gear Change Lever to engage with and move the Selector Rods to their respective positions for the various gears. You may be able to simulate the hot condition of the Gearbox by heating the Top Cover with a Hot Air Gun. If the issue is not caused by the bottom of the Gear Change Lever not being able to be moved to the Right far enough, and therefore, is able to engage with the Reverse Selector Rod, I can only imagine a few areas that may be causing the problem:

1. Inside the tower directly above the Reverse Gear Selector Rod, there is a spring loaded plunder with a hemispherical end. This hemispherical end should be able to engage in one of two annular grooves in the Reverse Selector Rod (see the picture following).



The groove it engages with is determined by whether the Selector Rod is in the Reverse, or Neutral position. This plunger may in some way be jamming when hot and not allowing the Reverse Selector Rod to move.

2. The only other area that involves the Top Cover is the Gear Selection Lockout mechanism at the front end of the Top Cover. By some obscure means, the Ball Bearing and Roller may be staying in a position that is preventing the Reverse Selector Rod from moving. I can't imagine this as a cause, but worth mentioning if the two Reverse Indent systems mentioned prove not to be the cause.

3. If all of the above prove not to be the cause, you only have the Reverse Gear Selector Lever (shown in the following picture), or the Reverse Idler Gear being able to move axially on its shaft, similarly as unlikely as the Gear Selection Lockout mechanism, but a place to look if everything else fails.



I feel the issue is more likely to be associated with one of the Reverse Gear Selector Rod Indent mechanisms.

I'm sure the Forum members would be interested in what you find.

Regards,

Bill

[Gerry]

Hi Bill read your well presented reply,the problem to me is the fact that reverse engages fine when the the car is cold?On my own car,an early 3.8 clutch adjustment and idle speed make a big difference to the engagement of the none synchronized first and reverse gears?

Regards Gerry 62 ots.

[angelw]

Gerry Wrote:

the problem to me is the fact that reverse engages fine when the the car is cold?On my own car,an early 3.8 clutch adjustment and idle speed make a big difference to the engagement of the none synchronized first and reverse gears?

Hello Gerry,
Notwithstanding that Raymondo's car is a 64 S1, with the 4.2lt engine I assumed his gearbox to be an All Synchro.

What are the adverse symptoms of your Moss Box when the clutch and idle are not adjusted just right? Is it a case that the gears grind when trying to engage them? I've asked the same question of Raymondo and he is yet to come back with and answer. There is a big difference is the cause of gears grinding and just difficulty to move the gears to engage.

Regards,

Bill

[Jaeger]

I have Mk2 3.4 Jag with exactly this problem on an all synchro Jag box. Most of the time the gearshift is light and sweet, but recently, when the car is hotter than usual, no amount of force will get the lever past the detent. All the gears engage very easily, it is just getting the lever past the detent. The gearbox is running 70/90 synthetic oil.
I have spoken to a gearbox specialist today and he says the detent is accessible from the top of the box and is adjustable.
The weird part is that once the car has cooled a little, say ten minutes, I can drive it quite normally again.

I would be very interested to know how the E-type box problem was solved before we start dismantling the car!

[tinworm]

If you can turn off the engine and then select reverse with no problem - you should return to look at the clutch adjustment/idle speed - I can't see that detent adjustment should change cold to hot.
Thats my opinion anyway

good luck
Barrie

[Sheds]

Thank you all for your replies - most helpful. I will update you once fixed. Thanks again for your time taken replying to my query.

Raymond, did you get this issue fixed? I have the same problem!!
cheers
Sheds