G-car with S-car gearbox?

[yeti]

I had a chat with a guy yesterday and we got into a discussion about the different gearboxes fitted to our cars - The Citroen or the Renault.

He said that he was sure that he had seen a G-car with an S-car box, but with inboard brakes.

Have anyone heard of that?

I have heard of S-cars with G-car boxes, but not the other way around.

Bjørn

[silverfrost]

Hi Bjorn,

Have never seen a G car with a renault box, I have seen stevens cars with the old gearbox and inboard brakes which would lead me to think that lotus used up the old gearbox in some of the early stevens to get rid of old stock, On that note i would say very very unlikly that a G car ever had a renault box fitted at the factory!

Regards danny

[Simon350S]

The only way you'd have an s box is if the brakes were moved outboard.

It will fit easy, same mounting points to engine, same gearbox mounting points and mounts, all you need is the different gear change setup and the S hubs.

All the arms and link rods on the suspension are interchangeable and if you e got a post 85 car you can reuse the original calipers with a little work and the shocks and springs will remain unchanged.

New discs, and a new set of wheels due to the different PCD

Probably forgotten a couple of things but that's a goodstart.

[silverfrost]

Also not that simple,

Otherwise hilly and myself would of just swapped over the rear suspension parts for the later ones!

My silver S3 is post 85,

Regards danny

[Simon350S]

How come? Thought it was as simple as that?

Yes I did breeze through it and missed a few bits but in sure the hubs are swappable.

[dazmans3]

It's been done, I saw a G car a couple of years ago that had been converted to the Renault box, even had the OZ alloys on it. I think it was in one of the Donny shows. So that car must be still out there somewhere.

[Simon350S]

I meant hub carriers not just the hubs obviously... Not enough sleep......

[silverfrost]

Hi Simon,

Looked into it before with various searches, posts etc and apparently its a no go! Thats what was posted on here, somebody was looking into fitting a later renault box and asked how hard it was, all the posts after that where saying the suspension could not be changed over, hence leaving the chap with the drama of the shafts and brakes, If the hub cannot be swapped the driveshafts will not fit, and so on!

I do hope your right though as it will be great for people doing conversions, but from what people have posted on here it has always been listed as a no go, Hence why I designed my own rear brake set up for the mutant .2. using audi parts that still involved a lot of machineing and fab work.

In another way i hope your wrong as i could of saved myself a lot of work and head scratching

Regards danny

[Simon350S]

I'm sure I remember the posts previous, fishy rings a bell?

From what I remember it was a lot of "I don't think it will work" rather than it's been tried and failed.

The upper and lower link arms are the same, the radius arm looks the same except for the mountings for the brake lines hence the change in part number.

I'm as positive as I can be without bolting one up or speaking to the factory that it will indeed swap straight over.

if a pair of rear hub carriers & shafts comes up for sale one day I may get around to saying one way or another for sure.

[silverfrost]

Simon,

IF it works it would be a fantastic thing for the G car owners, its a lot of work to for a gearbox change though

hopefully somebody will know a definate yes or no answer, Seem to remember hilly knowing a lot on the subject maybe he may post some more info on the matter,

Regards danny

[hilly]

As far as I can figure out it is do-able, just a matter of getting the right parts which is where the problem comes in.

New from Lotus they would cost a bomb, where as second hand parts don't appear very often.

You would probably need the rear uprights, brake calipers, rear hubs, brake discs, wheels, drive shafts, complete gear linkage assembly, exhaust box hanger and gearbox as a minimum. As you can see quite a long list and without a donor 'S' car it is unlikely you could get all this lot.

If it is a pre 1985 car then you then have the problem of how to get the front hub PCD to match the rears as the later units won't fit.

On pre 1981 car you won't have the upper link on the rear uprights and I don't know if the Renault box can take the axial load of using the drive shaft as the part of the suspension.

With respect to 'G' cars with Renault gearboxes, these are quite likely 'G' cars bodies on later chassis as is makes the whole process MUCH easier......

Hilly

[MrDangerUS]

UN-1 w/ INBOARD BRAKES conversion

If you want to upgrade the gearbox using bolt on parts w/o fabrication search for a Renault UN1- 027. They're getting pricey these days but it's an easy conversion with no welding.

Here's a conversion done by JAN HOEL. All of the nickel plated linkage parts and exhaust mounts he got from Mike Rodrigues.

http://www.facebook.com/photo.php?fbid=179165288761382&set=pu.178516808826230&type=1&theater

[R33S GT]

Awesome, I'm guessing this is a bette resolution than converting to outboard brakes? Though has anyone else ran a UN1 with inboard conversion like this, anyone foresee any issues doing it like this?

[MrDangerUS]

Tim,

here is the link showing chassis loop mods necessary to fit UN1 w/inboard Wilwood brakes

http://www.facebook.com/profile.php?id=100001391065878&ref=tn_tnmn#!/media/set/?set=a.178528142158430.44883.178516808826230&type=1

[R33S GT]

Thanks - useful page for me. Just trying to get my head around the changes!

[s2mikey]

I dunno how great it would be. Plenty of issues and complaints about the Renault box and with suppliers like Harry Martens and a few others coming up with some key parts for the Citroen box.... I think us G-car guys are actually OK.

Besides - take care of the tranny and gearbox and you will be rewarded with longevity, me thinks.

Edited March 8, 2012 by s2mikey

[V8-ESPRITS3]

I have already got a UN1 gearbox with Rover V8 bellhousing sat in the garage. I also have the S4 rear hub carriers, and was looking into doing the conversion and may still do it one day. Although have heard these gearboxes are still a bit chocolate. Did you see fifth gear attempt 200mph in a Esprit? the gearbox killed it. Twice! I say most things are possible if your willing to stick at it.

[Bibs]

The Fifth Gear thing was contrived for TV, so much so in fact that a producer resigned over it (and is a member of TLF).

[Jacques]

The way I see that old tv-show is, that they chose to upgrade on engine stuff and repairs, but they did not do one the most important thing - the gearbox, where stronger parts were readily available. I am sure, as the people I know who tune cars on a professional level, allways upgrade the internals of the gearboxes, that if Fifth gear would have done the same, they would have succeeded.

 

Cheers,

Jacques.

[Daniel]

For the power the standard G cars put out, the Citroen box is fine and in my experience much better to use than the Renault unit, so I don't get why one would wish to change?

 

Probably missing something, I usually am.

[Andyww]

For the power the standard G cars put out, the Citroen box is fine and in my experience much better to use than the Renault unit, so I don't get why one would wish to change?

 

Probably missing something, I usually am.

 

+1

 

Nope, dont think you are missing anything.

 

With some mods to the linkage, ie get rid of the rubber, fit a proper bearing to the pivot lever the Citroen box is absolutely fine.

[Simon350S]

This thread revival is in relation to a stonking V8 conversion with huge amounts of torque....

I completely get the thought process...

For me, originally I was looking at over 300bhp from my little 4cylinder, again with the rise in torque to match. My project hasn't happened....

[V8-ESPRITS3]

The way I see that old tv-show is, that they chose to upgrade on engine stuff and repairs, but they did not do one the most important thing - the gearbox, where stronger parts were readily available. I am sure, as the people I know who tune cars on a professional level, allways upgrade the internals of the gearboxes, that if Fifth gear would have done the same, they would have succeeded.

 

Cheers,

Jacques.

totally agree

[V8-ESPRITS3]

For the power the standard G cars put out, the Citroen box is fine and in my experience much better to use than the Renault unit, so I don't get why one would wish to change?

 

Probably missing something, I usually am.

I was really talking about people who do engine swaps like V8 installs etc, were the gearbox is the weak link and wanting a stronger replacement.

[MrDangerUS]

Re: C-35 Citroen box.

 

Looking at all the internet pics the drive side should be on the more vertical side of the crown wheel where the other side with the slope, coast, is supporting the load!! The Esprit is on the other side!

Thinking about how the Citroen box is installed, on SM, it is actually in front of the engine which makes the CWP design correct for driving the car forwards.

Lotus have the box going backwards!! I am not surprised that the CWP is always failing, they have the wrong design!!! The pinion is always trying to "escape", i.e. climb up the slope side of the crown wheel!

The more vertical side has to the the drive side! Geometry is all wrong!

Who is going to source a CWP with the correct profile in the C35 box?
 

Crown wheel and pinion are made of special hardened steel and are matching pair with numbers. They come in several ratios. Standard 8/35.Special track 7/34 and special for road cruising 9/35.

 

C-35 gear box was designed for a normally aspirated car producing a maximum of 170 ft lbs of torque.  The HCI Esprits made 220 ft lbs before bumping the boost to 9.5psi.  The C35 gearboxes came in an early version and a late version.  S3 car has the late version.

The problem with the transaxle is that it was never designed to handle the power of the Turbo 910. Lotus first used it in the 160 Hp 907/ 912 powered Esprits, and that was a good match. But when they stepped up to the 910, they took the Citroen beyond its original design intent. They made some changes to the Turbo version of the gearbox that were supposed to strengthen it, but it was make-up on a plain girl... she was still of humble origins.

If you're contemplating hotrodding your engine, then you need to understand that your limiter is going to be the gearbox. Besides the infamous circlip and differential carrier bearings failures,  CWP and the casing cracks are the most frequent failure modes.

Edited July 27, 2014 by MrDangerUS