Best way to upgrade gearbox and/or diff

[britcom58]

Hi,

I've had a quick search but cant spot the answer to this question - apologies if its there!!!

I have a US import series 2 roadster and wondered if anyone can recommend the best way to give it longer legs. Is there an overdrive upgrade that would avoid the need to change the diff ratio?

If not where is the best place to have a 5 speed box fitted and would this avoid the need to change the diff too? I'm based in North Yorkshire, not had the car long so don't know any classic car engineers who undertake this sort of work. Any recommendations would be appreciated.

Thanks in anticipation.

Brett

[mgcjag]

Hi Brett...welcom to the forum...as mentioned in another of your posts o/d is not an option for you..they can only be fitted to the longer wheelbase cars....so it a 5 speed option and or diff change....depending what your looking to gain.....lots of info on the forum.. heren is one of our longer threads just on 5 speed options...do your homework to asses whats best for you....Steve http://forum.etypeuk.com/viewtopic.php? ... eed+option
Edit...another link re changing to a 2.88 diff..one of our members James has posted quite a bit about the virtues and posted videos.... http://forum.etypeuk.com/viewtopic.php? ... &hilit=xjs

[christopher storey]

It is far easier and cheaper to change to a 3.07 diff than to go for a 5 speed box , which requires engine out. Also, as you will see if you research the 5 speed threads on this forum, many people have had problems with some of the conversions . For a suggestion on someone to do the work in Yorks, have a word with Andy Rayner at Hutsons in Bradford , 01274 669052 who will also be able to supply you with any parts such as different speedo drive dog, UJs ( unquestionably worth checking while the rear suspension is out ) etc you will need

[Nickleback]

I was in the same position as yourself over a year ago, no OD available for your car, 5 speed once you have done your reseach is really a mixed blessing and not an easy or cheap solution. So I opted to change my LS diff from 3.54 to 3.07 which keeps reasonable torque and give the car "longer legs" at motorway speed and drops the revs, by keeping my existing diff and changing over the crown wheel & pinions required with a specialist who did the whole diff and IRS rebuild for me at the same time.
Definately recommend the tripple SU's (Burlens) as combined with the above for substantial improved performance
Make sure you speak to Andy Rayner of Hutsons for advice, great guy, really helpfull for getting the right parts that you will need.

[Tom W]

I went for a 2.88 diff in place of the 3.54. It was cheaper and more readily available than the 3.07, and a whole lot cheaper than any of the 5 speed options. I swapped it over as part of rebuilding the IRS. The IRS needed work anyway, so the only extra cost was the cost of the new diff itself. I took the cover off the back of the new diff and it didn’t look worn, and it had similar backlash to the one that came out. So apart from painting the outside, I put it in as is. The gamble paid off, it doesn’t make any weird noises, and doesn’t leak. I figured if I pulled to to bits, there’s the risk it wouldnt go back together quite the same. Plus, I wasn’t sure how much I’d be able to improve anyway, as I’m not sure all the internal components are readily available anymore. It’s worth noting the speedo will need recalibration get after swapping the diff, it reads about 15mph out at 70mph.

The taller gearing doesn’t seem to have harmed acceleration, if anything it’s quicker as I’m probably in one gear lower than I was before. Steep hill starts do hammer the clutch a bit, but it’s flat where I live, so this isn’t a problem for me. It might get a bit tiring if I lived in a particular hilly area. Well worth the swap in my book.

[politeperson]

Tom

[britcom58]

Hi - thanks for all the responses. Ive put a call into Hutsons as recommended and will keep you posted.

Cheers,

Brett