Jumping out of reverse gear - 6 speed
Jumping out of reverse gear - 6 speed
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Discussion

Tim75

Original Poster:

21 posts

147 months

Sunday 6th July 2014
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Hi All, hoping i can get some advice. I am having a slightly different problem to Colinh2 (on recent thread). My spherical bearing is fine and the gear lever slides fine. Reverse engages (but is a bit clunky) but as i am part way through reversing, it pops out of gear and i get a horrible gear clash. Seems to happen more often when the engine is hot after a run. Any thoughts on what i can do? (transmission tunnel cover is off and ready). thanks!

downsman

1,099 posts

178 months

Sunday 6th July 2014
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Sometimes, if you're lucky it can be the transmission tunnel stopping the lever from fully selecting the gear.

Have you tried to see if it happens without the cover on?
If it has only started recently and this is the cause, it might mean the engine or gearbox mounts have failed.

If the lever is well clear, then you'll have a more serious gearbox problem, that I'm not qualified to diagnose.

Tim75

Original Poster:

21 posts

147 months

Sunday 6th July 2014
quotequote all
Thanks Downsman. I will give that a go. so i guess if that is the cause, then winding the gearknob up a little higher and re-fixing the grub screw would help? or something more dramatic? my car is a 2010 R500 with 7000km on the clock..would be surprised if it was the engine mounts. I will check by loading up the driveline and check engine movement.

downsman

1,099 posts

178 months

Sunday 6th July 2014
quotequote all
It may well not be the cause, but if it is it would be a quick and cheap fix so worth checking smile

framerateuk

2,851 posts

206 months

Monday 7th July 2014
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Mine does this! (Sigma 140 - 6 Speed)

It's been doing it since I bought the car at the end of 2012. My local specialist has taken a look at it and we still haven't been able to sort it - short of removing the box. He's drained the oil and checked it for metal fragments and it's been completely clean, so it doesn't appear that there's anything major wrong inside.

We've changed the engine and gearbox mounts and it still knocks out occasionally (ie, I give a little too much throttle). The car is perfect in the forward gears so I've decided to leave it and eventually if I start getting problems in other gears then I'll get the box out and potentially get it rebuilt.

Please let me know if you do get anywhere with yours!

Edited by framerateuk on Friday 11th July 13:02

Tim75

Original Poster:

21 posts

147 months

Thursday 10th July 2014
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Thanks Framerateuk! good to know its not unique to my car, but not good that its hard to diagnose without taking the box out..hmm.. I spoke to one of the guys at race and road transmissions and he suggested it is likely to be a slight manufacturing problem with the reverse selector mechanism. Nothing much else you can do short of taking it out and opening it up. There is some other piece under the gear lever bolt plate that can break apparently, but havent taken mine off yet to look. sounds like you already checked that? I will let you know if i find out anything else. cheers.

Tim75

Original Poster:

21 posts

147 months

Friday 1st August 2014
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So, I have done the following:
- checked at low engine temp with the tunnel cover off. no problems
- cut back the aluminium sheet of the tunnel cover around the gear shifter to increase clearance and free up the boot.
- cut slits in the underside of the boot sew joint around the gear lever to free up movement.
- raised the gear knob to reduce interference with the tunnel cover.
- checked at full engine temp and no better. still jumping out of gear.
- checked throwing it into 3rd or 5th before reverse to slow the gearbox down and compensate for lack of reverse syncro. no better.
- checked at very low load...ie. just creeping the car in steps...could just manage to hold it in gear.
- spoke to Road and Race and they didn't immediately recognise it as a known problem....

Seems in fact to be getting worse, as managed to crash the gears a number of times on a recent trip. almost unusable in reverse now. Would really appreciate any further thoughts. Would be unusual if Framerteuk and I were the only ones with this problem.

downsman

1,099 posts

178 months

Friday 1st August 2014
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It sounds like you've tried everything that can be done without stripping down the box frown

TVR4500cc

188 posts

198 months

Tuesday 5th August 2014
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My 2008 R500 did this

Reversed fine downhill or on the flat but put in too much load and unless you held it in gear it simply popped out

I spoke to a couple of Caterham gearbox people and one advised there was a fault on some early gearboxes that caused this. (Can't recall what and not a gearbox engineer but something like the original batch of selector forks were slightly too short???). I did speak to R&R and one other but can't recall who said what. Is there another engineer at R&R that may have different recollections of this issue??

They suggested unless the box was coming out or it was really annoying me, leave it alone.

It didn't affect any other gear and other than this she ran sweet as a nut.

Good luck.


framerateuk

2,851 posts

206 months

Tuesday 5th August 2014
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Well that sounds about right. Mine is an '09 Sigma so I guess it might have been built around the same time.

I've done 6 trackdays on it and nearly 8k (the car is on 18k now) and the problem hasn't got any worse (it hasn't got any better mind!). If the engine has to come out for some reason then I'll look into getting it fixed, but otherwise I'm going to keep it as is.

Tim75

Original Poster:

21 posts

147 months

Thursday 7th August 2014
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Thanks Guys. Appreciate the input. Does sound like a selector fork issue. So I just need to decide when to pull the engine out to deal with it..hmm.