86 Turbo Gearbox swap

[MGFCUP]

Finally got to the bottom of my gearbox prob on my 86 G Turbo,which was due to the fact that all of the internals swapped places!I have sourced a replacment box but when it turned up it has the slave cylinder on top and not on the side.Does anyone know if it is possible, or has anyone swapped the belhousings over before as this appears to be my easier route at present? The casing on mine is fine but the internals are totally shot.I have drawn a blank on finding a turbo box that doesnt need a rebuild !I have already fitted a new clutch /slave /braided hose so I do not really want to change to the later box .
Cheers
Richard
86 Turbo
87 H/C N/A

[B16 RFF]

MGFCUP said:

Finally got to the bottom of my gearbox prob on my 86 G Turbo,which was due to the fact that all of the internals swapped places!I have sourced a replacment box but when it turned up it has the slave cylinder on top and not on the side.Does anyone know if it is possible, or has anyone swapped the belhousings over before as this appears to be my easier route at present? The casing on mine is fine but the internals are totally shot.I have drawn a blank on finding a turbo box that doesnt need a rebuild !I have already fitted a new clutch /slave /braided hose so I do not really want to change to the later box . Cheers Richard 86 Turbo 87 H/C N/A

The box and the bellhousing are a matched pair (a machining operation I believe). So you cannot easily swap bellhousings.
The slave cylinder on the top means the box is from a pre late 84 non-turbo S3 (or earlier) model, according to the workshop manual.

Paul.

>> Edited by B16 RFF on Friday 21st May 11:46

>> Edited by B16 RFF on Friday 21st May 12:07

[MGFCUP]

Thanks Paul.
Why are these things always so complicated!Does this mean the bearings are matched I wonder.I have been told its possible to swap but could cause a problem later on .The work shop manual makes the removal sound very easy but does say that the Diff is attached to the belhousing.I suppose the next stage is to open both boxes up and have a look?

[B16 RFF]

MGFCUP said:

Thanks Paul. Why are these things always so complicated!Does this mean the bearings are matched I wonder.I have been told its possible to swap but could cause a problem later on .The work shop manual makes the removal sound very easy but does say that the Diff is attached to the belhousing.I suppose the next stage is to open both boxes up and have a look?

I'm fairly sure it's a machining operation on the bell housing that means the box mates to the engine accurately (input shaft aligned with crank I presume), but I cannot be sure as it was a long time ago that I read this, and I can't remember where.

[MGFCUP]

I,ve done a bit more digging and it should be possible but I need to make sure that the crownwheel is shimmed correctly to the pinion and the preload os correct on the drive shaft bearings ,not forgetting to replace the drive shaft seals.Assuming the internals are the same as are the drive shaft/diff bearings then the belhousing should fit .I,m going to give it a go unless anyone tells me otherwise and I,ll report back.I expect some carefull assembly will be required but It must be worth considering.
Thanks again

Richard

[B16 RFF]

MGFCUP said:

I,ve done a bit more digging and it should be possible but I need to make sure that the crownwheel is shimmed correctly to the pinion and the preload os correct on the drive shaft bearings ,not forgetting to replace the drive shaft seals.Assuming the internals are the same as are the drive shaft/diff bearings then the belhousing should fit .I,m going to give it a go unless anyone tells me otherwise and I,ll report back.I expect some carefull assembly will be required but It must be worth considering. Thanks again Richard

Well, best of luck, but as I understand the problem,it's not whether or not the bellhousing will fit the gearbox, but whether the box will be correctly aligned with the engine.
What about putting the internals from the new box in your old box/bellhousing combination?

Paul.

[lotusguy]

Hi,

The bell housing is totally interchangable. While you have the box out I would replace the primary shaft roller bearing, the synchros (or at least 2nd gear), the crossgate 'O' rings, and be sure to start out with a fresh nyloc thrust washer between the crank and the spigot/input shaft. In fact, I would consider upgrading to the Renault box sipot bearing, which will make the box last a lifetime over the citroen arrangement. Contact me for details.

In fact, unless it's a fitment issue, I would leave the slave on top, won't hurt a thing. I would look to add some insulation/heat shield so that the turbo heat doesn't affect it, which was the only reason it was swapped to the side anyway.

As far as checking runouts etc., be very careful. Make sure you have the proper knowledge and equipment. A new CWP is in the neighborhood of $2,200 USD, so you don't want to get this wrong. Happy Motoring! ...Jim'85TE

[B16 RFF]

lotusguy said:

The bell housing is totally interchangable.

What's your basis for saying that?

Paul.

[MGFCUP]

Hi Jim,
Great ,I couldnt see why there should be a problem !I have a mechanic locally as this is a bit beyond me but he has rebuilt a couple before and seem s to understand the run out checks on the CWP etc so we will see.I will check/replace the parts you have mentioned .I have already replaced the spigot bearing and the clutch but I,m interested in your opoint about the Renault upgrade,I it a straight swap over ?

Rich

[MGFCUP]

Jim,
Sorry I missed one point ,I understood that the Slave cylinder was on the side on all turbos and this was because it actually fouled the Turbo or something .Is this wrong as well ?

Rich

[B16 RFF]

MGFCUP said:

Jim, Sorry I missed one point ,I understood that the Slave cylinder was on the side on all turbos and this was because it actually fouled the Turbo or something .Is this wrong as well ? Rich

According to my manual, all Turbos had the side mounted clutch slave. NA cars switched to the side mounting in late 84. Presumably for commonality.

As for the interchangeability of the bellhousing, why not get professional advice and ring Lotus Cars or someone like Paul Matty.

Paul.

>> Edited by B16 RFF on Friday 21st May 14:14

>> Edited by B16 RFF on Friday 21st May 14:21

[MGFCUP]

Paul,
I have the manual and I agree with you ,as my 87 G has a side mounted slave.( However what left the factory was not always what is reflected in the Manual !)
I have spoken to 3 Specialists , 2 say its possible and one just told me to convert to a Renault box ( Great help).I will try Lotus but I suppose the only way forward is to strip both my boxes and have a look /measure.
What I will do is report my findings on here so that the question is answered.
Thanks for your advice.

Rich

[lotusguy]

B16 RFF said:

lotusguy said: The bell housing is totally interchangable. What's your basis for saying that? Paul.

Paul,

The transmission itself is the same box. Whether a Citroem 'C' or 'C-35', the case is virtually the same, only the drains are different and some of the internals.

The tranny may not be able to use the top mounted slave because the trunk floor is different between the models and it may obstruct. The turbo and it's intake trunking could also pose a problem. But as to the bellhousing, it simply bolts on. The gearcase is fully enclosed without it. Happy Motoring! ...Jim'85TE

[lotusguy]

MGFCUP said:

Hi Jim, ... I will check/replace the parts you have mentioned .I have already replaced the spigot bearing and the clutch but I,m interested in your opoint about the Renault upgrade,I it a straight swap over ? Rich

Rich,

The spigot bearing on the Citroen box is really an achilles heel of the whole system. It is a pretty feeble needle bearing with no real inner race for the input shaft to push against. It is the nyloc thrust washer which takes all the abuse. As such, once this goes away, the input shaft (hardened steel) will literally bore itself into the softer crankshaft (cast), eventually distengaging itself from the primary shaft at the other end, but not before destroying the splines on both the input and primary shafts requiring them to also be replaced as well. At this point, the crankshaft needs to be pulled and machined to accept an insert sleeve sold by Lotus for just this purpose.

The Renault spigot or pilot bearing is a true roller bearing, much more robust with an actual inner race which the input shaft rests against preventing it from boring into the crankshaft. It is not a straight swap, it would require that the crank be bored slightly to accept it (approx. $60 USD) and that the input shaft be turned approx. 0.001" to receive the bearing. If anyone were to experience the problem I outlined above, and eventually most will, this would be the ideal time to do the swap. I have not done it on my car, but the next time any attention is needed to this area I will. It's simple, spend maybe $100 USD and totally prevent at least a $1000 USD problem down the road. Happy Motoring! ...Jim'85TE

[dsvitesse]

The gearbox and bellhousing are matched. If you change the bellhousing it is possible the hole for the differential bearings is no longer a perfect circle wich will damage the bearings very soon, or the bellhousing could be a few hundreds mm to wide or to small.
Maybe it will fit, no problem.

Harry Martens

www.ds-vitesse.com

[lotusguy]

dsvitesse said:

The gearbox and bellhousing are matched. If you change the bellhousing it is possible the hole for the differential bearings is no longer a perfect circle wich will damage the bearings very soon, or the bellhousing could be a few hundreds mm to wide or to small. Maybe it will fit, no problem. Harry Martens www.ds-vitesse.com

Harry,

You are definitely The Man when it comes to the Citroen 'C' box. I most humbly bow to your expertise! Thanks for the Heads-Up. Happy Motoring! ...Jim'85TE

[B16 RFF]

lotusguy said:

B16 RFF said: lotusguy said: The bell housing is totally interchangable. What's your basis for saying that? Paul. Paul, The transmission itself is the same box. Whether a Citroem 'C' or 'C-35', the case is virtually the same, only the drains are different and some of the internals. The tranny may not be able to use the top mounted slave because the trunk floor is different between the models and it may obstruct. The turbo and it's intake trunking could also pose a problem. But as to the bellhousing, it simply bolts on. The gearcase is fully enclosed without it. Happy Motoring! ...Jim'85TE

I think you have missed the point, Jim.
In manufacture, the box and the Lotus-made bellhousing are made into a matched pair by a machining process. Hence, although you can fit any bellhousing to any gearbox, the resulting unit may or may not be serviceable. Nothing to do with the slave cylinder.

Paul.
PS Have just read dsvitesse's post. I think he is refering to the machining process I was trying to describe in my earlier posts, but time had dimmed the details in my memory somewhat.

>> Edited by B16 RFF on Saturday 22 May 00:43

[MGFCUP]

Many thanks Paul,Jim,Harry,
I will look around for a third gearbox! which is correct but I am going to check the bellhousing option out simply because I have the parts sitting here.I take your point Harry that it is 50/50 whether the bearing housings line up ,If fact the specialist who I spoke to said he had one car that had had this done which was fine ,the next may not be .It is presumably easy to tell if both housings are in alignment before the bolts are done up so I do not destroy the bearings .I will obviously check all of these clearences/preload/run-out measurements.Hopefully it will then keep me going for a ew hundred miles whilst I assemble the parts to convert it to a Renault box which seems to be what most specialists are beginning to suggest now.
Regards

Rich

[lotusguy]

MGFCUP said:

Many thanks Paul,Jim,Harry, I will look around for a third gearbox! which is correct but I am going to check the bellhousing option out simply because I have the parts sitting here.I take your point Harry that it is 50/50 whether the bearing housings line up ,If fact the specialist who I spoke to said he had one car that had had this done which was fine ,the next may not be .It is presumably easy to tell if both housings are in alignment before the bolts are done up so I do not destroy the bearings .I will obviously check all of these clearences/preload/run-out measurements.Hopefully it will then keep me going for a ew hundred miles whilst I assemble the parts to convert it to a Renault box which seems to be what most specialists are beginning to suggest now. Regards Rich

Rich,

The switch to the Renault box isn't that straightforward. The Renault box makes no provision for the in-board brakes which you have, so you're looking at some modification there to move the brakes outboard. Additionally, you will have offset issues with your wheels, so plan on replacing them as well.

It would make more sense, economically, to get a new bellhousing and have it bore aligned with the gearbox. Perhaps Harry can help you with this, or Lotus cars. The Renault box isn't a much better alternative to what you already have, a lot of work/$ for not much better a solution IMHO. Happy Motoring! ...Jim'85TE

[B16 RFF]

MGFCUP said:

Many thanks Paul,Jim,Harry, I will look around for a third gearbox! which is correct but I am going to check the bellhousing option out simply because I have the parts sitting here.I take your point Harry that it is 50/50 whether the bearing housings line up ,If fact the specialist who I spoke to said he had one car that had had this done which was fine ,the next may not be .It is presumably easy to tell if both housings are in alignment before the bolts are done up so I do not destroy the bearings .I will obviously check all of these clearences/preload/run-out measurements.Hopefully it will then keep me going for a ew hundred miles whilst I assemble the parts to convert it to a Renault box which seems to be what most specialists are beginning to suggest now. Regards Rich

You've discounted my earlier suggestion of building the internals of the new box into your old casing/bellhousing then? Or is it damaged?

Paul.