4 to 5 speed conversion

[edgyWedgy]

Hi,

Recently i have been able to get my hands on a nice 5 speed 'box.
I don't have any idea about how much kilometres the box has made,
but it looks clean and well, and there is no noticable play on either of the shafts.
I only do know that it's a box that has only been in a standard non upgraded 7. Selecting gears goes really smooth, in all of them.
The box itself was a bit greasy and dirty before i cleaned it, but i believe there are no leakages or any other defects. The greasiness made that there is no rust anywhere on the box.
I haven't noticed one so far. Tomorrow i will check the condition of the oil, and check if there's any swarf on the plug. I don't suspect there will be any though. This is how the box looks like now.


The point is, i'm doubting whether i should take it apart to verify its inner condition, or if i should leave it be and just mount it in the car.
The widely adopted philosophy about not maintaining something that ain't broke, has proven to be really true for me more than once, so hence my doubt.
It would be regrettable however, if i'd have to dismount the box right again because its condition isn't as good as i hoped it'd be.
There is a way to check the working of the oil pump i believe, so i'm gonna search how to do that, but are there other things i can check without taking the box apart?

There are also some other questions i'd like to get answered before i proceed with the conversion.
What parts do i need for the 5 speed to be able to fit?
Right now, my 7 is fitted with a standard 4 speed with a 3.63 diff, i intend to keep using this diff. The speedometer may be somewhat off but i'll take that in the bargain. The new box i got includes the bellhousing(with clutch lever), and the gearselector unit as you can see.
The output shaft has a flange with holes with spaces of 50 and 60mm between them, which i believe is the same as the 4 speed flange.
The total lenght from bellhousing to flange is 9 cm shorter than the 4 speed though so the propshaft needs some modification.
The input shaft has the same shape as the 4 speed, from what i remember, so that'd mean i can keep the standard clutch and clutchhousing that is also used for 4 speed cars.
As far as i'm aware, i only need a few adaptors for that bridge underneath the car to support the gearbox. And if the modification of the propshaft fails, i can always get a proper 5 speed one.

I'd like to hear your tips and advices on this procedure, as i guess there could be a few things i can do wrong here.
Thanks for the help, cheers.

[Beans]

You can use the original rear mounting bracket and mounting rubber, as they are the same.
You only need two new parts (UKC1743 + UKC1744) to go on top of the rubber mount (TKC1044).
Also the long central mounting bolt might need replacing.

As for the flanges, make sure that the central protrusion of the prop'shaft's flange is a snug fit in the gearbox flange's recess.
And finally before fitting the 'box, make sure the gearchange housing is fitted properly. The rubber bushes do perish.

[Howard722]

Regarding the remote mechanism mountings--your gearbox ass`y is missing the rubber bushes/spacers on the top two bolts where it bolts to the gearbox-the same double bush/spacer setup exists either side on the horseshoe shaped bracket that is between the speedo drive and rear flange.

[rosey]

You will also need to change the rubber gaiter, hold down plate and the decorative gaiter from a 5 speed because the gear stick sits in a different position.
I upgraded my 4 speed box to the LT77, the back axle and prop shaft, it was relatively straightforward but aligning the gearbox was tricky with the car on axle stands, I eventually used some threaded 10mm bar to align it to the engine and pulled them together.
I used 2 trolley jacks to adjust the gearbox height and plenty of wooden blocks, always useful for lifting, prizing, hitting things, throwing etc.
Best of luck.

[john 215]

Hi,

Personally would do the complete five speed conversion, stronger axle and saves messing around with propshafts etc.

Cheers John

[edgyWedgy]

Thanks for all your reactions

@rosey i understand from your post that it's possible to mount the 5 speed without taking out the engine.
Is that really hard to do it that way? I have access to a car bridge(cant find english translation, you know a lifting platform), so that could make things a bit easier. I'll try to modify the hold down plate to fit the new shifter, i diy'ed this 4 speed plate already anyway.. :p from sight i'd say the 5 speed sits only around 7cm further backwards, so i think it'll be possible to modify it accordingly.
The most important for me are the things that need to fit exactly, like the flange and the clutch shaft etc.
I hope i can keep the current clutch and clutch housing, but i'm not sure whether that fits.

@Beans that looks like just a spacer, supprises me that there are no other parts needed, but nice.
I'll take in mind the flange protrusion, hopefully they fit, and otherwise i'll try to make it fit with the lathe.
If i'm really lucky the 4 speed flange fits on the 5 speeds shaft, but i doubt that.
I already replaced the gear selector bushed, they indeed perish, they were almost completely gone, but everything fits tightly now.

@Howard 722 you're right it came in without as in the pic i posted, but i already made rubber bushes to properly support the gear selector assembly.

@john 215 the 5 speed propshaft is indeed better, but i'm already over my budget after the revision. The thing is that the gearbox set was priced so good(€100) that i couldn't let that deal go, so i bought it. Propshafts are not exactly low price either. I can always replace it later when i have saved up.

[Beans]

If you have access to a car lift it should be pretty easy.
Just don't forget these boxes are pretty heavy
A mobile hydraulic axle stand is highly recommended here, making it a one man job.

[march]

I have a prop shaft taken from a 5 speed conversion with a 4 speed diff if it is of any use to you?

[edgyWedgy]

So you mean you fitted a 5 speed box and a 5 speed propshaft to a 4 speed diff?
That would mean both 4 and 5 speed propshaft flanges on the rear (the diff side) are the same.
That would matter if it comes to it that i have to buy a 5 speed propshaft, so yeah thanks this info certainly is of use for me.
It'd be nice if the flanges on the other end are identical as well.

[march]

No - I haven't fitted anything to the car. I am currently dismantling it to put a new body shell onto it. It came with a 5 speed box, a modified 4 speed prop shaft and 4 speed differential. I will not be putting that combination back on - hence if any one is planning to put a 5 speed box on a 4 speed diff / axle I have a modified 4 speed prop shaft that will fit should anyone want it.

[edgyWedgy]

Well that is the exact kind of propshaft i'm planning to make too, since my setup is the same.
What setup do you choose then, and why if i may ask?

[march]

I am building a rally car so in all likelihood will be 4HA LSD axle / custom prop shaft and if I can afford it when I get this far an R380 Gearbox. The reason for this is is that it is a very strong solution for the abuse it's going to get and it meets the original Homologation requirements for the vehicle. On a note about 4 speed diffs - they tend to be a pretty weak affair and if you can stretch to a 5 speed diff I would strongly suggest it - unless you like the sound of diff whine in the mornings of course. 5 speed prop shafts are pretty cheap on Ebay as well.

[edgyWedgy]

If only i had the money to rebuild it to rally specs, but that'll cost a lot, especially in my region.
I have heard several components of early TR's are weak, so the gearbox which is the most important will be replaced by a stronger one.
The LT77 is strong enough for me i think, there's almost no visible difference between de R380 and the LT77 by the way. I wonder how the R380 can be so much stronger then. There are by the way more negative opinions about several TR7 components like the brakes, but they're fine i think. Maybe i'm not that of a demanding type.

I think i'll modify the current 4 speed propshaft, and then save up for a 5 speed, and maybe a 5 speed diff if i have money left over. There's not much whine to hear from the diff, and the engine drowns out other noises anyway.. :p