Throttle linkage assembly and bulkhead bush

[44DHR]

Further to my post regarding working on my friends 1966 Right Hand Drive 4.2 Fixed Head Coupe 2+2, we resolved the broken Choke Cable and after removing all three carburettors, freed the jets which were stuck due to petrol gum, we now have a new problem.
The Throttle linkage has play and this noticeable when trying to reduce the idle speed. Having cleaned the linkage, it is noticeable the rear slave shaft Bush, (C.24816) has split and due to the high degree of movement within the bush mounting hole on the bulkhead needs replacing which has had our heads scratching how to get access to remove it.
It is hard to understand how the two parts of the Throttle linkage are mounted in the carburettor manifold and we are now faced with removing all three carburettors again to access the central Adapter, (C.18942), which supports the Front and Rear Throttle slave shafts. We assume with the three carburettors removed, we can remove the front Adapter, (C.18941) supporting the Front slave shaft, which should then enable us to remove both front and rear slave shafts from the manifold, so we can install a new rear Bush. Could this be confirmed please ?

A second issue is that all the three Throttle Spring Lever Assemblies, (C.24927), have movement around the central circlip and appear to move on the SU throttle spindle which does not assist in reducing the idle speed. We imagine the carburettor end of C.24927 would have a half circular cut out shape to match the throttle spindle, but that also shows signs of slight movement on the shaft.



We are hoping but removing and cleaning up the two throttle shafts, if they were sticking that this would assist the throttle linkage to operate more effectively and shut off cleanly, but just wondered if the slight movement in the three C.24927 assemblies was normal or if they need replacing. It was trying to understand the reason for the central circlip, which encourages movement, rather be rigidly bolted.
We would appreciate your thoughts.
Regards,
Dave

[tim wood]

I’m just sorting my linkage out due to a sticking throttle the bush on the bulkhead was also sloppy.
Replaced it with one of these

https://www.ebay.co.uk/itm/306378377221

Bit of a fiddle to fit due to access but seemed to improve the overall feel

[40GT]

The bulkhead mount is a real fiddle, I removed the wiper motor lower bolts and loosened the uppers, this gave a slightly better access.

I turned my own bush from Delrin stock, taking into account that the longer the insert fore and aft, the more friction it will create as the engine moves, making operation stiff, so I tapered in front and back leaving a smaller contact surface that won't bind up as things twist out of alignment. Works perfectly so far, just need to keep an eye on wear.

[44DHR]

Many thanks for the responses regarding the troublesome bulkhead bush.
The primary question I am asking is - can the two slave throttle shafts be removed from the intake manifold while it remains bolted to the engine in the car ? I am concerned that even removing the three SUs, that there could be insufficient lateral movement to the slave shafts for their removal.
If anyone could confirm the situation please.
Regards,
Dave

[40GT]

If you remove the rear bracket as mentioned above, this will allow the rear linkage to be removed, then remove the two ball studs C18941/2 and the forward linkage can be removed. The ball part of these studs will probably be worn.

[44DHR]

Hi Sean,
I think we’re now getting somewhere in understanding the issue.
We were coming to the problem from the other way around to avoid removing the mounting bracket retaining the broken end bush. Because of the limited access to the bulkhead bracket is a known problem, with the second mounting bolt for the bracket being hidden up under the wiper motor (!), we were trying to see if we could remove the two slave shafts first in order to avoid getting anywhere near removing the bulkhead bracket.
I believe your answer is the definitive answer we were seeking - in that it is NOT possible to remove the two slave shafts until the bulkhead bracket is removed, which in turn enables the rear slave shaft to be pulled out of its mounting “adapter”.
Removing all three SUs may make general access easier- for all the effort expended - especially regarding the carb nearest the bulkhead requiring its mounting studs into the inlet manifold to be removed due to the proximity of the pedal box not permitting an outward removal movement.
I assume the only way to access the second bolt up under the wiper motor is to release its four mounting bolts to lift up the motor, but we were concerned any movement of the wiper motor inside the car could cause create further problems.
If we loosen the wiper mounting bolts, as you suggest at Post #3, is there any danger of parts falling off internally such as the very rare spring clip retaining the ball joint on the central wiper spindle bearing, or if everything should stay together.
Oh, how we love these old cars !
Cheers,
Dave

[40GT]

Hi Dave,

re the wiper motor, I had thought the same and that if something came away internally then this would be a nightmare, but I have removed the lower bolts a few times now, but the uppers were just loosened, plus I only ever lifted the motor just enough to get a 1/4 drive socket under and onto the hidden bracket bolt. It's not easy. I have an auto box in mine so there's another linkage to deal with also.

My memory on this job is not so clear but I'm sure I have done the removal with carbs still in place but then again I've had the carbs off twice now, so carbs on I wouldn't recommend it.

[44DHR]

Job done and thanks for the responses, especially Sean above.
Just thought I would give some “lessons learnt” to assist anybody undertaking this job. We had to remove the rearmost SU Carburettor, which greatly increased the access. Only thing is this is the really troublesome carb to remove as it is adjacent to the Clutch Pedal Housing and cannot be slid off the mounting studs, which have to be removed together with the carb.
As Sean stated, with the wiper motor bottom two 7/16 inch A/F bolts removed and the two top bolts slackened, it is possible to get a 7/16 inch A/F socket onto the two mounting bolts of the bracket supporting the rear Slave Shaft. This definitely was made easier by having two people on the job, one to support the loosened wiper motor lifted up and the other to undo the bolts. These bolts - including the elusive bolt under the wiper motor - are tackled using a small drive socket in towards the bulkhead as it is not possible to use a spanner in the direction of the bulkhead as the two heater pipes coming out from the bulkhead block access.
With the bracket unbolted and moved sideways, the Rear Slave Shaft can be removed and innocuous rubber grommet fitted into the bracket, the whole assembly can be refitted.



Photo showing the wiper motor being lifted to access the “hidden” mounting bolt on the bush mounting bracket, being highlighted by a torch shining on it. The black wire is the wiper motor earth wire which is normally under the mounting bolt head.



Another lesson learnt was that the Pin, (C.19450) linking the Rear Slave Shaft to the Front Slave Shaft has to be fitted BEFORE the Rear Slave Shaft is bolted back into the bulkhead, as it cannot be fitted after. Guess how we found that out - as everything has to be unbolted to enable this !



With the linkage all adjusted, it was very surprising how that new tiny little bush made the whole linkage far more effective with no movement anymore at the bulkhead bracket and the whole linkage working smoothly.

Another job done on my friend’s 1966 4.2 FHC 2+2.
Cheers,
Dave

[Iansparky]

I replaced the rubber grommet with an angular contact bearing fitted into a mild steel housing that I machined on my lathe, this locates the shaft precisely with no play, but allows for angular movement of the shaft due to the engine movement.
I don't have a photo unfortunately
Ian