free hit
counters
Esprit clutch hydraulic assistance - Gearchange/Gearbox/Clutch - The Lotus Forums Jump to content


Esprit clutch hydraulic assistance


Recommended Posts

I have had trouble for a while with my left ankle which is occasionally aggravated by the clutch effort on my Esprit GT3. It’s not the heaviest clutch ever experienced (that honour goes to a Capri Injection I once owned) but I think the angle of operation and sitting low doesn’t help.

I have tried to source a clutch pedal assist spring set from an S4s/Sport 300 but only half the parts are available from Lotus now. Bibs suggested that the parts were sourced from Vauxhall/GM (probably a Bedford truck!) but unless someone can identify this a Lotus engineered solution is not available. Plus I have never driven a car with one fitted, and persoanl opinions remain divided as to its worth...

Failing that option I understand a couple of V8 owners have helped the hydraulic operation by fitting single circuit remote vacuum servos, which I would try and copy although no-one has posted exact details. I like the look of this little thing which although a bit more expensive looks more compact than the default option of a Lockheed servo from an old Mini; http://www.carbuildersolutions.com/uk/compact-remote-brake-servo

Option 1 would be mounting the servo in the front boot area and splicing into the vacuum line for the brake servo. However I am concerned at possibly starving the brakes of sufficient vacuum or overloading the now unavailable Jabsco brake pump employed on the GT3. Has anyone replaced the pump with a higher output type? I have also considered using a vacuum reservoir (bulb type thing) but not sure if they are better mounted nearer the pump or beside the servo

Option 2 would be mounting the servo in the rear boot or engine bay, and taking a vacuum source from the engine, but apart from an unused (and very thin – 4mm?) takeoff for a redundant boost guage from the intake plenum I’m not sure where a reliable source would be? Any suggestions

Collective wisdom about either option would be appreciated. This will be a winter project so progress may not be instant!

 

In the garage no-one can hear you scream 

Link to post
Share on other sites

Upgrade today to remove Google ads and support TLF.
  • Replies 13
  • Created
  • Last Reply

Top Posters In This Topic

I had the clutch assistor spring fitted to my S4s & it about halved the pressure required to operate the pedal.

The servo from Kit Car Solutions looks good, easy enough to fit & would again halve the required pressure.

I doubt it would overload the vacuum pump as it's not in constant use. :thumbup:

Cheers,

John W

http://jonwatkins.co.uk

Link to post
Share on other sites

Given that the S4s Delco Moraine brake pressure switch is obsolete, I've been giving some thought to what I will do when mine eventually packs up (assuming it hasn't already suffered some loss in pressure).

The solution I have arrived at is to junk the whole lot and replace it with a conventional brake servo system, probably from the MR2. Because the S4s doesn't have an engine-driven vacuum pump, I have been looking at one of these http://www.hella.com/microsite-electronics/en/UP30-32-vacuum-pump-117.html to replace the pumped system. I just wondered if it might do for your proposed clutch servo, too. It may also provide enough vacuum for both brakes and clutch, but that is something you'd need to check.

Margate Exotics.

Link to post
Share on other sites

I'm not sure about current vacuum requirement from the brake servo or how it's even specced or measured! On the principle of hitting things with a big hammer I've spoken to a couple of people junking the Delco who have fitted vac pumps from a big Audi (which is also where the pressure accumulators  mentioned previously come from).  I could tee into the current brake vacuum supply and see how things go, and then fit one of your little Hella pumps as a clutch source if the brakes don't feel right. I just hope the feedback is obvious before disappearing through a hedge!

In the garage no-one can hear you scream 

Link to post
Share on other sites

The Audis (from my research) use the Hella UP28, the UP 32 is the biggest 12v automotive vacuum pump from Hella, but I suspect that neither of these would have any problem providing enough for your brakes. Also from my research, they are very reliable units.

As to whether one vacuum pump could run both brakes and clutch, that might be something you'd have to ascertain by simply trying it. Unless someone else here has already been down this particular road, you'll need to invest some cash to buy the parts to find out whether or not it works. A remote servo and Hella pump for the clutch sounds like a good idea to me, though. Plus, as the Jabsco vacuum pump is obsolete, a Hella pump to replace it.

 

Margate Exotics.

Link to post
Share on other sites

The servo idea certainly looks DIY friendly, although a bit space hungry on the boot areas. The clutch assist spring idea at least took up zero room, although I bet it would be the usual backbreaking job to fit like anything in the Esprit cabin/

In the garage no-one can hear you scream 

Link to post
Share on other sites
  • 6 months later...

Their clutch cylinders look plastic... Hasn't the Evora had problems with the clutch fluid boiling (there's a TSB to add heat shielding), and also with the plastic clutch hydraulics?

Travis

Vulcan Grey 89SE

My Lotus Photo and Projects Album

Link to post
Share on other sites
  • 2 weeks later...

Quick update from me.

I got into this thread as my gt3 had a massively heavy clutch. I simply couldn't press down on the clutch at the lights as before the change my leg would start to wobble !

I have other cars with heavy clutch from the 70s with cable operation and this was by far the heaviest.

I also had some judder so at the last C service I had my clutch replaced.

Absolutely transformed... not light but definitely much much lighter. i also don't have as much travel so I can actually sit a little further back...

Just spent a couple of days commuting with it on the new clutch and I can even sit in motorway jams without leg strain...

Let's see how long it lasts :)

Link to post
Share on other sites

Good for you. Sounds similar to my car when first purchased (wobble etc) which a Lotus garage said was down to poor adjustment. Whether that contributed to the eventual failure of the fork I'll never know. Without wanting to pop your bubble it will soon seem heavy again in comparison with other cars and you'll be back looking at assistance! If it's any consolation the clutch on a 2.8 Capri is even heavier, but IMHO the Esprit feels worse due to the driving position and lack of options for where to put your left leg.

In the garage no-one can hear you scream 

Link to post
Share on other sites

My TVR with 3L Essex with type 5 ford gearbox (same as 3L capri) is lighter than how my clutch was on the esprit before the clutch change, and I thought that was hard !

The day I took the esprit in the release bearing started to death rattle... so it was definitely time for a clutch !

Edited by Laika
Spellchecker. .. I have a TVR not a TV with 3Litre engine... although that suddenly sounds quite cool
Link to post
Share on other sites

I found this small Isuzu truck clutch booster on eBay. It needs to be re-engineered to Esprit configuration.

See eBay item number: 161666520573

Also, Maserati Merak had a hydraulic assisted slave cylinder, but they are very rare.

 
Link to post
Share on other sites
  • 2 weeks later...

Can anyone confirm what size the threaded fittings are on the Esprit's clutch hydraulic line?

The parts list shows the original red hose entering the brake master cylinder with a 3/8 UNF to 7/16" UNF adaptor - so does that mean the hose is 3/8 and the cylinder 7/16?

In the garage no-one can hear you scream 

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.




×
×
  • Create New...