1098 gearbox parts

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1098 gearbox parts

Postby Asolepius » Sat Apr 05, 2008 5:48 pm

I just pulled apart my ribcase and as expected the laygear is useless - 1st gear teeth eroded. I can get a new one for reasonable money, but I'm not sure whether I need to replace the 1st gear wheel as well. Its teeth look fine - obviously not new but no damage at all. Reverse is fine also. This is just a temporary fix until I sort out a 5 speed, so I'm tempted just to replace the laygear. The reason for hesitation is the very high cost of the 1st gear wheel - about GBP100. What do you think guys?

Looking at the parts catalogues made me think - what are the differences between 1098 and 1275 boxes? I am hard pushed to detect any!
Les Rose, Salisbury, UK
1959 Sprite, owned since 1978
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Re: 1098 gearbox parts

Postby Asolepius » Wed Apr 09, 2008 3:12 pm

Well as nobody warned me against going ahead without buying a new 1st gear, this is what I am doing. The new laygear arrived today, but I stupidly forgot that I will have to remove the circlips and distance piece from the old one. This appears impossible - unless anyone knows better? BTW for UK guys Minispares is good for gearbox parts, at around half the cost of some other suppliers (and nobody else had a laygear).
Les Rose, Salisbury, UK
1959 Sprite, owned since 1978
Asolepius
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Re: 1098 gearbox parts

Postby Asolepius » Wed Apr 09, 2008 4:57 pm

OK, I have solved my own problem! The circlips have tapered ends and can be lifted slightly with the end of a slim screwdriver, and then tapped gently all around until they come out of their grooves. Refitting them is slightly more difficult. I used a piece of suitably sized tube to push the clip in square. Only remaining problem is that the new laygear is 8 thou too short, and I am already on max size for the rear thrust washer. I checked the old gear and it's correct, so I had it right before. Back to Minispares tomorrow to see if they have even thicker washers.

I don't really mind talking to myself here! :)
Les Rose, Salisbury, UK
1959 Sprite, owned since 1978
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Re: 1098 gearbox parts

Postby Charlie Tolman » Thu Apr 10, 2008 1:26 pm

I really would like to offer some insight, but it has been nearly 20 years since I rebuilt a few rib-case transmissions, including a Webster-geared dog-ring version.

Perhaps you could seek guidance from some of the people on the nearby Salisbury Plane (in jest).

Charlie Tolman
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Re: 1098 gearbox parts

Postby Asolepius » Thu Apr 10, 2008 2:48 pm

Don't worry Charlie, just kidding. I phoned Minispares today but no joy, they don't have thicker washers. They said they would go off and measure all their laygears, but I've heard nothing more. So I bought some shim steel and will have to take up the slack with that. Not ideal of course but this is a temporary measure until I find a solution to the 5-speed problem. If anyone wants custom shims made I now have a wide range of thicknesses...... :)
Les Rose, Salisbury, UK
1959 Sprite, owned since 1978
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Re: 1098 gearbox parts

Postby Charlie Tolman » Fri Apr 11, 2008 12:43 am

I have used some of those unique custom shims when fitting new parts into the Webster-geared transmission.

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Re: 1098 gearbox parts

Postby Asolepius » Mon Apr 14, 2008 3:20 am

I now have the box assembled - correction - I have assembled it about 20 times and still can't get the selectors to work properly. 1st-2nd and 3rd-4th work OK, but reverse seems to upset things. I have replaced the selector rods with spares from the oddments box, and have cleaned out all the channels for the interlock balls and plunger. The gears themselves engage and disengage smoothly. As I say, forward gears are fine (better with the `new' selector rods), but when I try reverse it's very stiff to go in and then won't fully come out, locking the other gears. Panicking now as I have to get this and a host of other jobs done for the Sprite 50th at Goodwood in a month's time. I have spent more time on this than I would have done fitting a 5-speed if I could get one. :(
Les Rose, Salisbury, UK
1959 Sprite, owned since 1978
Asolepius
1098cc
 
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Re: 1098 gearbox parts

Postby Charlie Tolman » Tue Apr 15, 2008 1:27 am

I am not sure why there is a problem with your reverse gear engagement and dis-engagement.
The condition of the detent on the selector rod is very important, as is the condition of the ball or plunger ( short rod with two rounded ends ). How about the adjustment bolt/screw on the end of the reverse gear selector rod, to limit the total travel.
In an " emergency", complete the assembly, and never use reverse gear.
Some of my fellow Sprite / Midget racers would have a block-out bar mounted on the transmission tunnel near the gear-shift lever, so that reverse could not be engaged unless the bar was moved.

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Re: 1098 gearbox parts

Postby Asolepius » Tue Apr 15, 2008 3:07 am

Thanks again Charlie. I think I have narrowed it down to the interlock plunger at the rear of the box. This seems to stick in its channel. This gearbox has never had a particularly good action especially for reverse, and I suspect this channel has been wearing and causing the plunger to rock.

I am not aware of an adjustment screw on the end of the selector rod. Not shown in the workshop manual. I thought the travel was limited by the reverse gear wheel itself.

I think I will have to give up with this casing, and transfer the internals to my other ribcase which is in the car. This has even worse noise from 1st gear, but it does have a much better action. Of course the laygear will certainly not fit without shimming, but I have the materials now!
Les Rose, Salisbury, UK
1959 Sprite, owned since 1978
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Re: 1098 gearbox parts

Postby Charlie Tolman » Wed Apr 16, 2008 12:49 am

An adjustment screw or bolt on the end of the selector rod, might have been in my Webster-geared conversion transmission.

Spring and ball (or plunger) logic can be confusing and very touchy.

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Re: 1098 gearbox parts

Postby Asolepius » Wed Apr 16, 2008 3:44 am

OK I now have the answer. Using a very bright light I was able to see that the interlock plunger bore is badly worn, allowing the plunger to rock and jam the selector rod. I can't use the case like this. I'm wondering whether it might be possible to sleeve the bore. This would allow me to keep the car running while I do the work, and then swap gearboxes. A bit of brass tube of the right size ought to do the job.

I've always been surprised that these plungers and balls work in soft ally bores. How they don't wear out in a few years is beyond me.
Les Rose, Salisbury, UK
1959 Sprite, owned since 1978
Asolepius
1098cc
 
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Re: 1098 gearbox parts

Postby Charlie Tolman » Sat Apr 19, 2008 12:35 am

Two hard metals, or two soft metals, in sliding contact, will wear faster than a hard metal and a soft metal in sliding contact. The transmission oil helps to reduce the wear.

The brass tube might work well. However, it must be permanently located in its new bore, and must have the correct inside diameter for the ball or plunger.

A machinist might be able to drill out the plunger hole, plug this hole with aluminum, and drill a new hole of the correct diameter, but it might be a challenge.

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Re: 1098 gearbox parts

Postby Asolepius » Tue May 13, 2008 9:44 am

I am going backwards not forwards, in a manner of speaking. I got the defective ribcase repaired with a brass sleeve in the interlock bore. All went back together and I spent a whole day trying to get it to work. This time it went into reverse - not very smoothly but before it didn't do even that. All seemed well - into all the gears, until coming out of reverse again all selectors locked up and nothing would move. By this time I had pulled out the engine and other gearbox so was up against it - with the 50th birthday bash at Goodwood at the w/e. I tried the other rear cover and remote control and still no better. The problem is just so elusive - sometimes it works and sometimes not. So I pulled apart the box I had just removed from the car and put the good gears into that, having checked that all the interlock bores were good. BTW the gear cluster is fine and all gears select perfectly without the selector rods installed. Result - not much better. So I have had to dust off my very old smoothcase and put that in for the interim. Oh joy, very quiet, but my God that low 2nd gear and weak synchro.

I'm not really expecting anyone to spot the problem here, but just thought you would find the story entertaining :)
Les Rose, Salisbury, UK
1959 Sprite, owned since 1978
Asolepius
1098cc
 
Posts: 489
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Re: 1098 gearbox parts

Postby vagt6 » Tue May 13, 2008 10:13 am

Thanks for sharing your experience with the gearbox.

Sadly, it reminds me to have a professional involved. :roll:

Good work, job well done!

--Mark in C'ville
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Re: 1098 gearbox parts

Postby Charlie Tolman » Wed May 14, 2008 12:41 pm

Regarding the transmission woes, have you installed a different set of shift rods and detent balls / plungers ?

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