5 Speed Gearbox conversion for 3500S

#1
Hi,
I am new to this forum an loving every visit. So much information!
Throughout ownership of my 3500S, now nearly 30 yrs. I have dreamed of a 5-Speed gearbox, and now seems a good time to make the move. Existing 4 speed was rebuilt professionally 6 or 7 yrs ago, and still good, but the gear change is not a good as it could be, occasionally baulking at any change. I have replaced the gear lever and bushes, but no great improvement.
I am due a bonus of about 1000 pds. later this year. Would it be possible to convert to 5-speed for this? I would have o have the work done by a specialist Rover mechanic, as my days under the car are finished.
Looking through old posts, I think hat I need to locate a LT77 gearbox; I see that there are some on E-bay. do I also need a new bell-housing as per the ne Rimmers offer?
Does any supplier offer a new gearbox, as if I go ahead with the conversion, I want it to last?
Should I buy the cheapest LT77 box I can find and have it rebuilt by a specialist?
It seems that a new prop-shaft and clutch will also be needed,?
I have never driven a P6 with a 5-speed; is it really a worthwhile thing to spend my money on. I am not interested in performance, well not much, but I want the car to be pleasant to drive.
Any advice on gear box choice or likely budget would be very much appreciated.
 

cobraboy

Well-Known Member
#2
Welcome Robin.
Oh boy you are going to get some pro's con's and lively debate on this one.
My story here...… 5 speed install and off to the painters !

Yes it is worth it, I don't know if a grand will cover it, depends on how well you buy, bellhousings can be new or used, flywheel, clutch, auto prop will be needed.
Quiz mrtask on here, he is almost there on his conversion.
There are quite a few twiddly bits to collect that you need to get right, otherwise there will be hold ups.
Finding LT77's is getting harder, R380 is another option.

Google Vitesse Global Ltd
sales@vitesse-ltd.com

Alec Poole ex racer is sales director and they offer a 5 and 6 speed Mazda MX5 conversion for an MGB and Rover V8 and would like to fit one to a P6, but it aint cheap.
 

quattro

Well-Known Member
#3
I fitted an LT77 to my old car, and my present one had one fitted when I bought it. I would wholeheartedly recommend the conversion.
I must admit that I didn't really notice the change with the first four gears, but cruising at 70mph on the motorway, it will drop the revs from around 3,000 to around 2,500 making it a lot quieter.

Careful what type of oil you put in though, as the gear oils can make it notchy and very difficult to change. I use Redline MTL in mine and it does give it a really slick movement.

Make sure that you get a 2WD version, and if you're lucky you may get one with a V8 bellhousing, which would save you a few quid.

Richard
 
#4
Cobrboy,
I Looked at the Vitesse-ltd web-site. Very impressed with what they offer, but as you say, not cheap. Still that give me a realistic budget to think about. Searching through this forum has already told me that 1k is not going to cover the bits, let alone labour, as I am not u to trying to do this outside my flat. If, I go ahead, I want to have a conversion that will last my Rovering days, and not fit a clunky old 5 speed that will make driving a misery.
I had wondered about alternative gear-boxes. I remember from my MIdget days, that one company was offering Toyota gearbox 5 speed kit for Midget. Maybe not up to V8 torque, but what about Supra boxes? I am a great admirer of Japanese engineering.
I am visiting UK next month and ill b e talking to Rover places about this conversion, so I will be in touch with Vitesse as well.
Frist priority will be reviving the car and service after a winter in the lock-up. Then see about the electrics; new fuse box probably needed, as last yer all the light flickered when I went over speed humps. Electric section of the Forum has given me some more ideas for lighting upgrades.
Final question:- Dos a gearbox upgrade to 5-speed count a significant modification and make me need an MOT??
Great to have joined this forum.

Robin.
 
#5
they used to put supra boxes on the back of 350 chevy lumps so it will handle a rover.

re mot i would not of said a 5 speed would count as a significant modification, BUT i firmly believe no car should be driving around without an mot. around 50% of all P4, 5 and especially P6's we mot fail on brake performance, single circuit brake failure leaves you with NO brakes at all, surly its not worth risking lives for teh sake of the price of an mot?
 

cobraboy

Well-Known Member
#6
We put Tremec 5sp units from this outfit behind Jag XK engines at work. TREMEC 5-speed 6-speed Transmission Conversion solutions for classic and modern muscle
But I think the bellhousings come from Australia, and the mob there do a Rover / Tremec bell, but I cant remember the Aussie supplier name ATM, I'll try and find out.

Edit

Found it https://dellowconversions.com.au/pr...aft-to-rover-v8-3-5l-4-6l-manual-bellhousing/
Or
Rover V8 to Tremec T5 Bellhousing
Or
Conversion Components

Sooner or later LT77 supply will dry up, so it's good to know alternatives are out there.
 
Last edited:
#7
We put Tremec 5sp units from this outfit behind Jag XK engines at work. TREMEC 5-speed 6-speed Transmission Conversion solutions for classic and modern muscle
But I think the bellhousings come from Australia, and the mob there do a Rover / Tremec bell, but I cant remember the Aussie supplier name ATM, I'll try and find out.

Edit

Found it https://dellowconversions.com.au/pr...aft-to-rover-v8-3-5l-4-6l-manual-bellhousing/
Or
Rover V8 to Tremec T5 Bellhousing
Or
Conversion Components

Sooner or later LT77 supply will dry up, so it's good to know alternatives are out there.

I bought a kit from Conversion components a few years ago to fit a 5 speed Toyota box into my Rover 2000. It worked well for me.
 
#8
Thanks for all the advice. I looked at gearboxes for sale on the net yesterday and while not many LT77 or 380 there were a lot of BMW 5-speed, or 6-speed, ex 3 series or 5 series. I wondered if anyone had used one with the Rover V-8. I do not have figures handy, but 3L BMW must have more power and torque than the Rover lump. Anyone ever tried this??
I have been told that supplies of Rover LT77 will dry up soon, and with the original 4 speed not the strongest box, we will need some alternative to keep our cars on the road.
I have driven a BMW 330 cdi and as impressed. That was before diesels went out of fashion, and I thought of it as a possible replacement for the P6. Most impressed by the 6-speed box, cruising at 70 with just over 2000rpm.
Penguin; I agree with your sentiments about MOT. When my P6 goes for it spring service with Duncan Gill, I will be asking him for an MOT style check and if he thinks I should put he car in for a test, I will. I have not had a MOT failure on brakes for years, but last year I had to replace a leaking rear caliper and both front discs, so it keeps me up to scratch, though I want to have a car that is 'fit for purpose.

Robin.
 
#9
Hi again,
I have been searching for gearboxes ro sale and have seen a lot of 5 -speed boxes, but most if not all LT77 advertised are said to be from land Rovers.
Is there some subtle difference between LR and Rover gear boxes? If I go ahead with the conversion, will any LT77 be OK or will I get different atios in a L/R box?
Will all of the "variaions" of the LT77 fir on my P6 which I believe needs a SD! bell-housing. these things seem easy to find.
Any advice will be appreciated.

Robin.
 
#11
Peter ZRH, are you saying that all LT77 or only ex- LDV boxes have the low 1st. gear?
I have seen LT77 advertised as ex Land Rover Discovery; do these have a low 1s gear? If the box is overhauled/re-built, can the gear ratio be changed.
If I go to the expense of fitting a 5-speed box, I would consider having the box overhauled before fitting, as I do not want to start with a gear-box that was on its last legs. I want to end up with a car that is good to drive.

At the moment, I am wavering about taking the risk on this conversion, as there is not a lot wrong with my 4-speed, except that the change is not perfect, compared with my modern Toyota. but what 40yr old car is?? perhaps I should save the money and concentrate on other parts of the car, and keep driving until something happens that forced me to change the gear-box.
For instance, what do I do if the De-Dion Elbows are found to be rusty and unsafe?
Thanks to the Rover Club, I have now sorted the vapourisation, so I want to drive the car and enjoy it.
 

colnerov

Well-Known Member
#13
Hi, Stay away from the Land Rover gearboxes they are too different to be any use, they have a longer first motion shaft because of the deeper bell housing and the mainshaft is different because it goes into the transfer box.

Colin
 

cobraboy

Well-Known Member
#15
Sorry
I was not recommending a Landrover box, merely meaning the company might be worth having a chat with if you need one rebuilt.
 

colnerov

Well-Known Member
#16
Sorry
I was not recommending a Landrover box, merely meaning the company might be worth having a chat with if you need one rebuilt.
Hi, Yes I realised that, they are however very knowledgable about them and can supply rebuild kits. I was answering his query about there being lots of LR ones about.

Colin
 

harveyp6

Well-Known Member
#17
You will lose your reverse lights, your speedometer and your odometer unless you invest in some extra engineering.
To get the reverse lights to work, all you need to do is connect 2 wires to the switch, how difficult is that? And as for the speedo, getting the head recalibrated is easy, and if the car was manual to start with the original speedo cable fits with the most minor of mods. I'd hardly call any of that "engineering".
 
#19
Once again, thanks for advice and warnings. I am now more optimistic than when I began these thoughts on 5-speed boxes, when I was told that 5-speed boxes were like hen's teeth. At least I know that all is not lost if my 'box fails.
I think for the moment that I will hold fire and re-asses my 4-speed.
I'll be back in UK this week, and car is due spring service at Duncan Gill's. I'll get his opinion on my 4-speed and go from there. I hope to get to the local P6 meet in SW London and get more info from there. Looking forward to classic motoring again.
Robin
 
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