LT77 gearbox 'C' or 'D' ??

[sprevett]

Hi - does anyone know if a suffix 'C' box will fit into a 350i instead of a 'D'? As far as I know, the D was a strengthened version as used in SD1 Vitesse, the C being from a smaller, standard SD1. My D version has died, and I have a C as a spare in my garage which I intend to get looked at before I fit it, but I wondered if there are any major (i.e showstopper) differences such as input shaft length/diameter etc. etc..

any help much appreciated
steve

[chassis 33]

They are interchangable, the internals are different, not the spline (1"x23 splines) or the output flange.

If you need more info see here www.rpiv8.com/transmission-3.htm

Regards
Iain

[sprevett]

thanks Iain. the rpi site doesn't refer to the C suffix. do you know what it was fitted in? are the ratios the same?

[chassis 33]

Yes the ratio's are the same,
5th 0.833:1
4th 1.000:1
3rd 1.396:1
2nd 2.087:1
1st 3.321:1
Rev 3.428:1

Unless the C box is from an early Series 1 SD1 or the diesel, in which case
5th is 0.792:1 or 0.77:1 respectively

Info gleened from www.roversd1.co.uk/tech_data3.htm

Regards
Iain

[sprevett]

that's great - thanks again. Mine is a 19A....C type box so I assume it's some variant from an early SD1 but it sounds like it should work OK then- but I'll get it checked over anyway for condition of synchros/oil pump etc.before I have it fitted. The place recommended to me is Competition Transmissions in Markyate, Herts.

[JR]

Best to use the guy who designed the box and restores them for very reasonable prices, IMHO. Ask Andy for more details?

andymadmak said:

Ken Tomlinson was the man who designed the transmission for Rover back in the early 1970s. Ken is retired now, but still runs a little specialist rebuilders called N+T transmissions, based at Over Whitacre near Birmingham. He can tell you all about how the box came into being, and why they used ATF fluid from early in the production cycle.
Ken says that most transmissions run on ATF in high torque usage will fail prematurely and most of those will not be worth the effort of rebuilding because the wear is so great. The racing Rovers used SAE 75 / 80 gear oil by Motul. I use the Catrol synthetic equivelant (SMX or SMS, can't remember) and the change is fine except for the first few miles on the very coldest mornings, and even ten it's really only the 1st - 2nd change thats a bit sticky. TVR did not use ATF fluid when they used the gear box - the handbook says to use SS80.

[sprevett]

thanks for info - is there a number for Ken? he's not listed on Yell.com and a number I have seen for him on another thread doesn't work (beginning 01203..)thanks again

[JR]

If all else fails try giving this guy a call: www.pistonheads.com/gassing/profile.asp?h=0&memberId=18409

IIRC he put andy in touch with him. Or of course e-mail www.pistonheads.com/gassing/profile.asp?h=0&memberId=12835

Good luck, J

[mikeb]

I had a peek at my box today (oh-er) and it had 'F' stamped in it, so does this mean this its an 'F' varient. I know it is F***ed but aside from that what special features did the F type boxes have anybody know?

Only asking as I need it re-built and didn't want to take it out only to find that you cannot get the bits for it...

MikeyB

[wedg1e]

'F' was the last version I think: supposedly stronger bearings fitted, maybe a different 5th ratio to give a better cruise.

I have a spare box, ex-TR7 though so only a 'D' IIRC. It would work, just that with your 450SE launch technique it'd last.... oh, all morning, I should think...

[mikeb]

Are you trying to say my driving style is a bit 'Dutch' Ian? ;-)

MikeyB

[sprevett]

wedgepeople, I have now sent my 'C' type box to Comp Trans Srvices for a re-furb and I'll post a reply when I find out what they're going to do to it and cost etc. General opinion (nice chap) seems to be that a number of variants will physically fit (same input shaft diameter and number of splines etc) and that strength of bearings is the differentiator, so assuming that a re-furb would include a re-fit the best bearings available now anyway I assume it's not an issue.

[shpub]

wedg1e said:

'F' was the last version I think: supposedly stronger bearings fitted, maybe a different 5th ratio to give a better cruise.

There are G and H versions but they are like hen's whatsits. Bigger bearings etc and the strongest version of the box. The 520SE used to use C/D versions with Bernie's magic touches. Now running a H type with custom straight cut internals.