Caterham 6 speed transmission issues?

[SK400]

Greetings everyone

I finally got my R400 on the road and took it to Lime Rock, CT, a few days ago for a first real try on a track. What a blast!

 

However, mid day, I started to have issues with my 6 speed Caterham transmission especially downshifting from 5th to 4th and sometimes going from 4th to 5th. Very surprising especially that I have approx 350 miles on the car at most (I bought the box last October 2013 directly from Caterham UK). The 4th gear will simply not engage properly, especially after accelerations, even after multiple matching RPMs, double clutch etc.. All other gears engage well, including reverse, and there are no synchromesh "crunching" noises .. I tried to adjust the travel on my clutch pedal to ensure a full release of the clutch, but I'm still having a stubborn 4th gear that won't engage smoothly...

 

Does anyone have any clue of what might be going on? Has anyone experienced similar challenges with this transmission? What should I look for / try or test?

 

FYI - I use Redline MTL

 

Thank you very much for your help in advance!!

[yellowss7]

I found this recent thread on Blatchat. Don't know that it answers your question. But it seems that he has a similar issue with a new six speed. http://www.blatchat.com/t.asp?id=241618

 

Tom

[SK400]

Yup.. That's exactly it Tom.. Thanks for the reference link... when I shortshift or drive at low RPMs, no real issue but when I rev up, I can't engage the 4th (up or downshift) properly. Any hypotheses of what can be the root cause of this issue?

 

thanks Tom

 

Seb

[yellowss7]

I just posted on Blatchat to see if the problem was ever identified or fixed. Will let you know if they respond.

 

Tom

[yellowss7]

just got a response.

 

Hi Tom,

I have replaced the clutch slave cylinder and removed the lid to have a look at 3rd and 4th syncs but there in the rear part of the housing.

 

so I ordered new ones from Caterham and its now all back together sort of, just making a new oil tank and moving some water piping and the oil heater/cooler.

 

If its still not right when I test it there will be enough time to remove it and repair it.

Caterham recommend a 80w oil.

 

Chris

 

Not a resolution but hopefully more info will be forthcoming.

 

Tom

[SK400]

Tom

Thanks a ton for asking the Blatchat person about this issue. On my end, I contacted the Caterham UK guys but with no real concrete progress or answers on next steps so far. I've also connected with Taylor Race Engineering in the US who are Quaife gearbox distributors. Had a good chat with them but should have a better sense of my options next week.

 

In the meantime, do you of anyone in the US who might have a 6 speed gearbox available (for buy, rent, barter etc).. for the next few weeks while I sort this thing out? just curious, just checking options

 

I'll keep you guys posted on investigation progress.

thanks again for the help !

 

Sebastien

[xcarguy]

Seb,

 

You might give these guys a try:

 

http://www.taylor-race.com/

[SK400]

I did , thanks. The guys are on the road this week, I should know more about my options with them early next week

Seb

[yellowss7]

Just saw this on BlatChat.

 

http://www.blatchat.com/t.asp?id=241087

[SK400]

Thanks Tom

Quick question.. do you know who is the supplier of the standard H pattern 6 speed CSR caterham gearbox? The Cateham guys told me it was not Quaife..

thanks!

[yellowss7]

http://website.lineone.net/~dmch2/options.htm#6SP

[woolleybac]

Hi there this is my first post on this site and I have the answer to SK400 question.

My new box is doing the same as yours with 4th giving the most problem, I have found that its the 4th gear getting tight on the main shaft and some times when the clutch is pressed the gear stops/sticks on the shaft with the teeth not aligned so it will not engage 4th.

If you double clutch and get the gears to spin again it will go into gear, this only happens as the box is warming up and by the time its hot it changes gear very well.

I found going from 3rd to 4th it would not go in, I kept the clutch pressed and rolled to a stop.

There was no way it would go in any gear, I could feel the syncro's trying to slow the main shaft and only when I let the clutch out in neutral to get the gears to spin would it engage gears again.

I don't think there is damage taking place its just very hard to change gear until its up to operating temp.

Good luck.

[TurboWood]

http://website.lineone.net/~dmch2/options.htm#6SP

 

I've read elsewhere that the final 6spd was not made by BGH and that maybe there remains some friction there.

 

Daniel

[SK400]

Thanks Wolleybac

Have you contacted Caterham Customer Service about this? I ask because it would be great to bring this to their attention.. and you might still be eligible for warrantee (although a pain to send the box back to England, I see my whole summer going by before resolution..). You are now the third person with new 6 speed transmission problems specifically with 4th gear (unless you are the person from South Africa with the Birkin on blatchat with the same issues). All but 4th gear for me work well, regardless of temperature. I'd love to find out the root cause for this. A few hypotheses:

- Alignment teeth on the collar or brass ring are prematurely worn and it leads to a "point to point" synchro teeth situation, . Some people call it "shift blockout"

- Premature wear or wrong tolerance between the synchro ring and the key (between collar, shaft hub and synchro), allows the synchro to over-index and leads to blockout again

- synchro ring touching gear on side face (not on cone angle), the synchro will turn with the gear and not allow to engage .

 

Any other thoughts?

thanks a ton

[woolleybac]

Hi SK 400 Yes you are correct I am Birkin S3 ZA from South Africa and the Birkin factory is about 8 miles away.

I have contacted Caterham but no reply yet, if it needs stripping I will do it myself to save a lot of time.

I don't think its the problems you mention, this morning when I pushed the car out of the workshop the shaft was tight making the feel like the hand brake was on.

I am sure its just a tolerance problem and mine only comes free when the outer aluminium casing gets hot.

As aluminium expands more than steel this could be part of the reason its loose when hot? I don't know yet how many heat cycles it will have to go through to stay loose all the time.

My next race is in two weeks at Kyalami race track, one thing is sure it will get hot

Chris.