Gearbox crunch

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DCMVan70
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Gearbox crunch

Post by DCMVan70 »

Hi Everyone

A little while back my daughter picked me up from the station in the van. It is great to see kids driving classics and learning about chokes and how to reverse on the mirrors!

I jumped in the car to drive home and immediately noticed that I was getting a crunch going into second gear. At first I thought syncromesh, but then realised it was doing the same going up into second as well as coming down from third, and double declutching did not seem to help much. Going up from 1st to second only crunched when it was a fast gear change. I also noticed that it seemed better when I made sure I pushed the clutch all the way to the floor.

I adjusted the clutch (probably too far) so there was very little travel in an attempt to make sure was fully engaged. This improved things no end, but the crunch is still there on very fast up shifts and coming down into second.

Am I over thinking this, is it just syncromesh has gone on second, or could it be something else?
I was asking before I go looking for a gearbox or someone to rebuild one.

Regards
David
philthehill
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Re: Gearbox crunch

Post by philthehill »

Try and change gear slower and see what the difference if any is.
What oil do you have in the gearbox?

DCMVan70
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Re: Gearbox crunch

Post by DCMVan70 »

Hi Phil

If I change gear slowly it is all good, you really dont feel anything on the upshift, and the downshift is much easier.
With regards the oil, I am not sure, it is there from when I bought the car 2 years ago, I did have a look and it is clear and seems OK, other than being quite smelly. Maybe should have changed that earlier!

Regards
David
philthehill
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Re: Gearbox crunch

Post by philthehill »

I would recommend that you change the gearbox oil before doing anything else.
Smelly oil indicates to me that it has been in the gearbox for some time and the oil may be EP80/90 which has a distinctive smell.
If you do not have the correct and clean oil in the gearbox the synchro cones do not clear of oil leading to difficult and noisy gear changes.

jagnut66
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Re: Gearbox crunch

Post by jagnut66 »

Smelly oil indicates to me that it has been in the gearbox for some time and the oil may be EP80/90 which has a distinctive smell.
I always thought you were supposed to put engine oil in our gearboxes?
That's what I have been putting in mine for years now anyway...............
Best wishes,
Mike.
1954 Series 2: 4 door: "Sally" -- Back on the ground with (slave) wheels and waiting to be resprayed......
1970 Triumph Herald 1200: "Hetty" -- Driven back from Llangollen in Wales (twice.....)
myoldjalopy
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Re: Gearbox crunch

Post by myoldjalopy »

Indeed, that is the case for most models, Mike (although I believe the early MMs were different? Perhaps a MM owner can confirm?). However, if the oil in the OP's box is 'smelly' then, as Phil suggested, it is possible that someone inadvertently put in EP90 at a previous date......wouldn't be the first time!
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geoberni
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Re: Gearbox crunch

Post by geoberni »

myoldjalopy wrote: Fri Nov 19, 2021 10:33 am Indeed, that is the case for most models, Mike (although I believe the early MMs were different? Perhaps a MM owner can confirm?). However, if the oil in the OP's box is 'smelly' then, as Phil suggested, it is possible that someone inadvertently put in EP90 at a previous date......wouldn't be the first time!
According to the manual the MM Gearbox, Steering rack and Rear Axle were all EP 90.
The gearbox changed to Engine Oil with the SII, the steering and Axle staying at EP 90.
Basil the 1955 series II

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liammonty
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Re: Gearbox crunch

Post by liammonty »

You haven't said what year your car is, which makes a difference. the earlier gearboxes, in cars up to the end of 948 production in '62, have weak 'cone' synchromesh, which is really easily beaten. I routinely double declutch my '62 car down into 2nd gear toi avoid crunching it, but all changes need to be done slowly enough to allow the weak synchromesh to do its job. Ribbed gearboxes fitted to 1098 cars, from 1968 onwards, had much better baulk ring synchromesh, which works more like in a modern car, so if you've one of those boxes and you can't eliminate the 'crunch', it's likely the 'box is quite worn.

As Phil says, change the oil as it should be done every 3000 miles (from memory) and this may help. As others have said, if you happen to have a Series MM (unlikely I guess) the gearbox needs EP oil :-)
myoldjalopy
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Re: Gearbox crunch

Post by myoldjalopy »

Agreed - my hybrid 948/803 gearbox is easy to crunch if you rush it........So I don't. 8)
DCMVan70
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Re: Gearbox crunch

Post by DCMVan70 »

Hi All

Thanks for the suggestions.
The van is 1970, and while it now has a bigger Marina (?) engine, I am assuming is on the original gearbox which would have been mated to a 1098 A Series originally.

I am going to change the oil and see if anything changes - might have a look for a serial number and take a picture to confirm identification while at it.

Regards
David
philthehill
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Re: Gearbox crunch

Post by philthehill »

Before you do anything determine the make and model of the gearbox.
Whilst the Minor uses engine oil in the gearbox the Marina uses EP90 Hypoid.

DCMVan70
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Re: Gearbox crunch

Post by DCMVan70 »

Hi Phil

Thanks for that I will check - my gearbox has no synco on first, so I always assumed was a Minor one. Did Marina gearboxes have syncro on first?

Regards
David
StillGotMy1stCar
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Re: Gearbox crunch

Post by StillGotMy1stCar »

Marina box has syncro on first and you lift the gearstick for reverse.

Regards John.
DCMVan70
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Re: Gearbox crunch

Post by DCMVan70 »

Hi All

Thanks for all the suggestions.
I finally got round to changing the gearbox oil - it is a standard ribbed casing Morris box I am pretty sure - with some classic 20/50W engine oil. I also adjusted the clutch so I has the 1 1/4" travel before it bites.
Unfortunately, no change, it seems more and more like the syncro is going.
I will keep an eye out for a decent gearbox.

On the other hand, as I have a 1275 engine, and a standard van differential, everything is pretty low geared at the moment - what would be the consensus on an alternate gearbox - perhaps with syncro on first so the kids struggle less? Anyone have good experience with newer gearboxes, or should I get a standard and change the diff (one day?)

Next thing you know I will be looking for an automatic choke!

Regards
David
oliver90owner
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Re: Gearbox crunch

Post by oliver90owner »

You will almost certainly need a five speed box to achieve any higher top-gear speed.

I very much doubt bottom gear is needed for most ‘normal’ driving, particularly once rolling.
liammonty
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Re: Gearbox crunch

Post by liammonty »

As per oliver90owner's comment, you'll need to go down the 5-speed route if you want lower rpm in top at a given speed. The usual conversion is a Ford Type 9, but they are hugely expensive and quite rare now (and not a great 'box in the first place in my experience of driving Fords with them in the past, with 5th gear being weak). Plus you'll have to get a conversion kit. I'd teach your kids to handle first gear on the standard gearbox, unless they want to contribute to the cost of a newer box with synchro on first!

If you want more relaxed cruising, the easiest 'fix' is to fit a 3.9:1 or 3.7:1 diff from a Midget or Wolseley or Riley 1500. They too are pricey now, but not as pricey as a 5 speed conversion!
Pete Bags
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Re: Gearbox crunch

Post by Pete Bags »

I found this table on another site - I fitted a 3.7 diff to my slightly warmed up 1098 minor, and my Rev counter confirms the numbers given with my 165x70R14 tyres. I hope this is of use to you as well. The diff has certainly made driving more relaxing at faster speeds!

Edited to add: I have the standard ribbed Minor gearbox.
rpm.jpg
rpm.jpg (259.68 KiB) Viewed 1285 times
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