Vixen 5 speed gearbox conversion

Vixen 5 speed gearbox conversion

Author
Discussion

chris52

1,560 posts

182 months

Monday 24th November 2014
quotequote all
Dollyman1850 said:
Using exhaust brackets attached to the main lower chassis rail is less than ideal but i suppose will counteract the rotational torque of the gearbox rather than relying on the original mounting point alone.
As said earlier the flat plate solution does work whether referred to as a custom mount designed by a professional engineer or a just called a flat plate!

The correct and neater way to do it would be to cut off the existing chassis brackets and then weld the simple new mounts to the chassis to allow a correct gearbox mounting bracket (readily available) and correct damper mount to be used at a location directly below the gearbox mounting point.

I am also happy to send anyone a template of the chassis mounts which can be made in less than 10 minutes.





N.
A nice conversion but could I just ask why you welded the mounts on upsidedown if you had welded them on the same way the factory had you would not have needed to fabricate such a complicated centre mount with bends etc, just a flat piece of alloy or steel would have sufficed or have I missed something?
Chris

GPW41

150 posts

142 months

Monday 24th November 2014
quotequote all
Dollyman1850 said:
The old essex box is a different thing altogether…Very nice ratios and bomb proof.. I had a whining one on the back of a 5.0 cobra replica..we couldn't break it.
Sorry to hijack the thread, but are you referring to the 4 speed essex box here Neil?

Regards

Dave

Dollyman1850

6,316 posts

249 months

Monday 24th November 2014
quotequote all
chris52 said:
A nice conversion but could I just ask why you welded the mounts on upsidedown if you had welded them on the same way the factory had you would not have needed to fabricate such a complicated centre mount with bends etc, just a flat piece of alloy or steel would have sufficed or have I missed something?
Chris
Yes. you buy the complicated centre mount for tuppence hap'ny over the counter at a rally supplies specialist then set the chassis mounts to suit the driveline phasing. The mounts are the right way up and braced to the chassis rail The correct gearbox mount is being used with the gearbox it was originally designed for and a better quality rubber mounting. if you have looked at a few vixen mounts you will realise that they come in all degrees of out of flatness wink
N.



Dollyman1850

6,316 posts

249 months

Monday 24th November 2014
quotequote all
GPW41 said:
Sorry to hijack the thread, but are you referring to the 4 speed essex box here Neil?

Regards

Dave
Yep. The 4 sp single rail is a lovely box.. The external rod linkage one less so
N.


Adrian@

4,289 posts

281 months

Monday 24th November 2014
quotequote all
ATE399J said:
Essex V6 requires either a "special" at about £500 from Burton (IF they have one) or finding a bellhousing from an Essex V4 and we all know there are plenty of those around!
Anyway, l decided l like my 'box with the overdrive even if the ratios aren't the best.
I do a exchange Essex V6 conversion of the current 4 speed bell housing as a KIT to suit the M Series, inc quick-shift, used for the HD version of the type 9, clutch/prop/trim, as the OE items, gear lever mod (along with advice on how to calibrate the speedo, with speedo cables available ) , at lest than half the Burton unit, obviously not for the racing boys, as they want the weight saving of alloy and perhaps a T5 box (thinking about that I also do a conversion kit to the T5)...but.
Adrian@


Edited by Adrian@ on Monday 24th November 21:45

chris52

1,560 posts

182 months

Monday 24th November 2014
quotequote all
Dollyman1850 said:
Yes. you buy the complicated centre mount for tuppence hap'ny over the counter at a rally supplies specialist then set the chassis mounts to suit the driveline phasing. The mounts are the right way up and braced to the chassis rail The correct gearbox mount is being used with the gearbox it was originally designed for and a better quality rubber mounting. if you have looked at a few vixen mounts you will realise that they come in all degrees of out of flatness wink
N.
This was not meant as criticism of your work and I have looked at plenty of Vixen chassis but I have never seen the gearbox hanger mounts welded on that way round, but as long as it works thats all that matters I have done a very similar conversion on mine but have just copied how the original mounts were fitted and jus welded them on further back, but left the originals in place for easy reversal if needed. With regards the rest of the conversion I have gone down the Avo twincam route which keeps the original slave cylinder on an alloy bellhousing I have also had to use the lotus twincam clutch flywheel release bearing and clutch fork. Not installed it yet as the car is still in a thousand pieces lol so cant say if it works well but it should do.
chris

ATE399J

729 posts

236 months

Monday 24th November 2014
quotequote all
Adrian@ said:
ATE399J said:
Essex V6 requires either a "special" at about £500 from Burton (IF they have one) or finding a bellhousing from an Essex V4 and we all know there are plenty of those around!
Anyway, l decided l like my 'box with the overdrive even if the ratios aren't the best.
I do a exchange Essex V6 conversion of the current 4 speed bell housing as a KIT to suit the M Series, inc quick-shift, used for the HD version of the type 9, clutch/prop/trim, as the OE items, gear lever mod (along with advice on how to calibrate the speedo, with speedo cables available ) , at lest than half the Burton unit, obviously not for the racing boys, as they want the weight saving of alloy and perhaps a T5 box (thinking about that I also do a conversion kit to the T5)...but.
Adrian@


Edited by Adrian@ on Monday 24th November 21:45
I'll start saving!! Certainly something to cosider if/when the 'box or O/D goes bang.

I have the "lots of rods down the side" box as fitted to Zodiac V6 not the Capri 'box.

lazysprite

9 posts

161 months

Monday 24th November 2014
quotequote all
Alternatively you can use this mount - it allows the chassis to remain unmolested and puts the gearbox rubber in the correct place.
I've no idea which Ford bin it comes out of, when I picked up my gearbox, it was already attached, but it seems to put everything in the right place. What it does show is the torsional stiffness that Ford thought was necessary to put into the cross member, rather than the flatish plates that tend to be put in otherwise.
I've also used the RS2000 alloy bellhousing (behind a Zetec) with the LH starter motor housing removed and blanked off so you can get a sensible exhaust run without cooking the starter motor. The RS2000 housing has a starter motor mount at both 4 oclock and 8 o'clock.
I have experienced bleed issues with the Saab (AP Racing / Burton) concentric clutch release if the bleed pipe doesn't come out of the cylinder at its highest point (like a brake caliper). In its original application the green (Ford) cylinder also bleeds out of the top - although routing the pipe out of the unused clutch arm window does look tempting....
Don't forget to put an adjustable stop on the clutch pedal, the concentric cylinders are easily blown apart with too much travel or if you depress the clutch pedal with no engine fitted! (I've done it when doing an emergency engine removal and rushing too much!)





Edited by lazysprite on Monday 24th November 23:20

griff 200

509 posts

192 months

Tuesday 25th November 2014
quotequote all
I think people on both sides of the fence are right hear . The idea of leaving the old mounts and making adapter plate to do the job so the car can always go back is a great idea . I do like thick alloy plate nylock unf bolts etc but the clamps although will of course do the job could be better for the reasons brought up love to see a block type mount ??? Right I'm getting of the fence now. Richard

Dollyman1850

6,316 posts

249 months

Tuesday 25th November 2014
quotequote all
chris52 said:
This was not meant as criticism of your work and I have looked at plenty of Vixen chassis but I have never seen the gearbox hanger mounts welded on that way round, but as long as it works thats all that matters I have done a very similar conversion on mine but have just copied how the original mounts were fitted and jus welded them on further back, but left the originals in place for easy reversal if needed. With regards the rest of the conversion I have gone down the Avo twincam route which keeps the original slave cylinder on an alloy bellhousing I have also had to use the lotus twincam clutch flywheel release bearing and clutch fork. Not installed it yet as the car is still in a thousand pieces lol so cant say if it works well but it should do.
chris
No offence taken Chris.
I hope anyone on here can see all of the pics and as ever there is always more than 1 way to carry out the work ending up with the same result. I could have left the original bracket in place but I doubt the car will ever see a 4 speeder again.
N.

Dollyman1850

6,316 posts

249 months

Tuesday 25th November 2014
quotequote all
prideaux said:
Phil I thought you where a Mechanic you should of anyone see that the support is designed so the original mounts take the most of the weight and pressure and those brackets serve very little in the way of support the thickness of the plate is also important.
I would rather trust someone who was managing single seat race cars at Silverstone and later part of a race team and latterly an engineer in a engine workshop than over engineered kit cars and yes if loose not good and to tight the same but that applies to every screw bolt or fastener on your car
Andrew

Edited by prideaux on Tuesday 25th November 07:29
My God Phil..Are you not a mechanic? You mean you don't race single seaters at Silverstone?? Didn't you study :Moments: at school. hehe
N.


DavidY

4,458 posts

283 months

Tuesday 25th November 2014
quotequote all
I'm going to play devils advocate here but why swap the original box for a five speeder, the way I see it is:-

Pro's

You get a slightly more relaxed cruising rpm, and better mpg

Cons

Most 'Classics TVRs' do minimal mileage so the only Pro is negated
You spend a shed load of money doing the conversion which takes years to recoup in better mpg (new bellhousing, gearbox, mounts, propshaft, gear lever assembly, etc)
Often your gearstick is now in the wrong place!
If you want to hillclimb/sprint the car in an entry level roadgoing class, it is now effectively an illegal car (though loads get away with it)

Only a few things to consider, before we even get to best engineering practice!!!

missingbadly999

Original Poster:

348 posts

114 months

Tuesday 25th November 2014
quotequote all
Most modern driving is at a much higher speed than in the 60's and 70's, so it makes sense to change particularly as its a ford conversion - the 4th gear always seems too short to me anyway. I personally don't hold with the idea of bike carbs/zetec etc but the gearbox change is more subtle and not seen as a radical departure. To cruise at lower rpm has wear benefits and I don't think anyone is too bothered about mpg either way or we wouldn't be driving TVR's.
Does anyone know the reduction in rpm at 70mph?

RCK974X

2,521 posts

148 months

Tuesday 25th November 2014
quotequote all
As far as I remember Ford 5 speed boxes have a final ratio around 0.8:1 ish, so approx 20% reduction in rpm for same
speed, T5 has a bit more, at approx 0.75:1.

Of course there are different gear sets too.....

Tech question, no judgements or anything - I thought the annular clutch slave cyls had reliability problems ? Or has that now been fixed ??

It looks really neat on those photos I have to say....

Adrian@

4,289 posts

281 months

Tuesday 25th November 2014
quotequote all
IMHO, the best thing to do to V6 Essex is converting to 5 speed, it is livable with as a 4 speed and there is no doubt that the 4 speed is robust, but a 5 speed 'makes' the car (even without a consideration of changing differential ratio, because the 'real' conversion is to consider that also).
IMHO of course...worth doing, worth every penny, no you are not ever going to get anything back, other than having the driving experience and pleasure.
Adrian@

DavidY

4,458 posts

283 months

Tuesday 25th November 2014
quotequote all
But the T5 has a dreadful gearchange compared with the Ford 4 speeder, so does it really improve the driving experience??

davidy (with tin hat on!!!)

RCK974X

2,521 posts

148 months

Tuesday 25th November 2014
quotequote all
I agree with the T5, or rather that there aren't many gboxes with changes as good as the Fords, especially the 'B' type (3.0 and 2.8 4 speed) very strong and beautiful silky change.

Adrian@

4,289 posts

281 months

Tuesday 25th November 2014
quotequote all
DavidY said:
But the T5 has a dreadful gearchange compared with the Ford 4 speeder, so does it really improve the driving experience??

davidy (with tin hat on!!!)
David ...there are T5's AND T5's, (don't mention any other T...versions) and with it you cannot go cheap and cheerful, there are versions of the syncro rings that stall the gear change (making it SOOOOO SLLLOOOW), getting a 'known' gearbox is worth a fortune, because paying out, to sort the gearbox is stupid money, the problem is that opening a gearbox up and looking inside is beyond most peoples expertise, and the guys who know what they are doing know this!!

WITH the RIGHT internals the T5 IS better...IMHO of course...again,

Regarding both the type 9 and the T5 conversions, the guys who re-configure the differential ratio (spending the money doing the whole job properly and getting bigger 'rewards') will tell you this.
Adrian@



Edited by Adrian@ on Tuesday 25th November 10:11

tomtrout

595 posts

162 months

Tuesday 25th November 2014
quotequote all
Yep, I'm sure the conversion makes sense for the every day drivers and those who want to eat up motorway miles. Given the choice, the only T series I would want for motorways has the word Bentley in front of it!


ATE399J

729 posts

236 months

Tuesday 25th November 2014
quotequote all
prideaux said:
Phil I thought you where a Mechanic you should of anyone see that the support is designed so the original mounts take the most of the weight and pressure and those brackets serve very little in the way of support the thickness of the plate is also important.


Edited by prideaux on Tuesday 25th November 07:29
Yes, you are absolutely right, the mountings to the original pick-ups will take the majority of the load and the Nylocs you've used should ensure that everything stays nice and tight smile