MK1 Differential in my MK2

[Joner]

Hi, I seem to have a 3:89 diff in my MK2 Vitesse.  I've got to the point with this car where by it is running very nicely, all problems with engine, suspension brakes etc are sorted but its redlining at about 75mph in overdrive.  I haven't checked the serial numbers but I'm pretty sure I have a 3:89 diff when I look at the table on the Cranley classics website.

I'd really like to rectify this as at present the car is not practical on a long distance motorway run.  Two problems are:

The diff in the car is a good one.  I'm pretty sure the £500 + £180 exchange on Rimmers is based on my exchanging for a knackered unit.  Does anybody want to buy a 3:89 diff or have a 3:27 they want to sell?

Will the 3:27 go straight back into my car?  At some point somebody put this MK1 diff in, not sure why but will they have made significant modifications to do this?  

Any help and advice much appreciated.  

[GT6 M]

but its redlining at about 75mph in overdrive.

In what gear, 2 nd OD, !!!!
even a 4.55 will doo moer than that.

As its workin oot at 12.5 ish MPH x 1000 rpms, against 21 ish for 3.89
Speedo,or rev counter no right me tinks,or both.!!

should be dooing 21 mph x 1000 rpms in top

A 3.27 ina Vit,wida 2L maybe pushing it abit. esp wid an OD  init.

3.63 would be a better bet.
22 an a bit in top OD

M

[Joner]

Thanks for the response GT6 M.  The speedo is definitly ok.  I checked the calibration when I bought it because I didn't want to get a ticket. Rev counter is a bit suspect.  I'll check it out, but it does seem to be thrashing it when it gets near the red line.

Not sure what you mean when you say

Quoted Text

A 3.27 ina Vit,wida 2L maybe pushing it abit. esp wid an OD  init

According to Rimmer Bros the 3.27 is the correct dif for the MK2 2 litre besides, this car is quoted as having a top end of approx 100mph and from the Cranley classics tables the 3.27 is the only one that's going to give that speed.

[heraldcoupe]

The mechanical revcounters are notorious for their inaccuracy. Try and hook up an electronic tacho to see how the readings compare.

Cheers,
Bill.

[thebrookster]

I think there must be some confuzzlement here Joner!!

I use James Carruther's site for doing rpm/speed checking, can be found here: http://www.mintylamb.co.uk/gearspeed/

The original Mk1 Vitesse (1600 engine) would have had the 4.11 diff fitted.
The Mk2 (2 litre) would have had a 3.89 fitted as standard.

However, either way if you check the actual rpm against speed for 4th OD, the 3.89 should give engine rpm of 3400 roughly, whereas the 4.11 would be 3600.
This definitely suggests your rev counter is out!! On a standard Vitesse with no mods, I would reasonably expect about 100mph at redline, assuming a redline of circa 4500 rpm.

What Marcus is saying above is the 3.27 ratio will be too low for the engine. You will find pulling away from the lights, or in fact any kind of acceleration will be seriously degraded. This ratio is best left to those with seriously tricked out 2 litres and the 2.5l engines that have more torque. The 3.89 would take you back to standard, or if you want a lower cruising rpm without affecting the acceleration to greatly the 3.63 would be a better choice.

First things first however, get hold of a satnav or smartphone with gps, stick a gps speedo on it and check the speedo is working correctly. Use the mintylamb site to give the correct rpms for your car (assume a 3.89 for this) and see how it compares to your rev counter. The waggly needle effect on both rev counters and speedo's on our cars is a well known phenomenon!!

Cheers,

Phil

[Joner]

I think the confuzzlement is clearing now.  I'll check the rev counter out but I think it may well be to blame.  It isn't very stable and sometimes it doesn't work at all. You assume a red line of 4.5k which I had to double check so just nipped down the car park and my counter's red line is at 5.5k.  Is this the wrong rev counter do you think?

[thebrookster]

Your red line of 5.5k is likely correct, however do take into account the state of your engine! If it has never been rebuilt or is tired I would advise keeping a lower rev limit for safety, however if it has been rebuilt or you know it is in good condition then I cannot see anything wrong with 5.5k! That is your judgement call really!

I run my my 2l (in a 2000 saloon, but same engine) happily up to 5.5k, and probably over (lack of a rev counter means ignorance is bliss for me ).

Phil

[Joner]

My view on this is that I want my car to be in good working order.  I use it every day and intent to keep it that way.  I've got a spare engine, I think mines pretty fried, I don't particularly want to trash it on purpose but I want to run it to its expected limits and if something gives then that's the way it goes.  I'll download a speedo, calculate where I'm at with the rev counter I've got and if its out of kilter I'll get an accurate rev counter and see what happens when I push it up to the red line.  Fingers crossed and I'll let you know how I get on.

[thescrapman]

I would expect Orange segment to be at 5500 and redline at 6000. Is that right for a Mk2 Vitesse?

Or is it Orange at 5000 and redline at 5500?

You could try a Mk3 Spitfire rev counter, that will make the redline 6500.

[GT6 M]

Me tinks ye got a rev counter out ofa 4 cyl car.
look on the fronts, therea code, read off the code and search it out.

Ona GT wid 3.89 the figs are 3.55.1 under where it says RPMx100
and under Smiffs, it says RN-2318/00  

maybe diff fora Vit, but maybe not,  think the 3.55.1 is the important bit.              

Vits wer never offered with a 3.27, dont care what rimmers say.

Nick J has a 3.63 in his, so too have a few others,
and his goes well.
Nick, advise please.

Col, orange line 5500-5900,   6000 red line

M

[Nick Jones]

3.63 (standard in Spit 1500) is a good ratio for a Vitesse 2L provided the engine is a good one.  They are under-geared from the factory, though if you have overdrive the 3.89 is ok.

I have a slight dilemma in that I like the tall gearing for cruise (3000 rpm is just over 70mph), but my current engine like to rev.  Even using the factory red line I can only legally reach it in first and second......  It will reach it and more in 4th no problem (in Germany!).  In a GT6 shell I reckon it'd have a good go in 5th too!

As an aside, the 3.63 diff makes it possible to reach 60 in second gear without exceeding the red line.........

OP needs to check tacho and speedo as already mentioned as he should be nowhere near the redline at 75 in top - 75 should be only 5500 rpm in direct 3rd!  Also worth checking whether the diff has a round input shaft or square one.....

Nick

[Pete Lewis]

all 2 ltr vitesse were only 3.89  no other option was offered.    think Rimmers have a data problem or typo.


only GT6 had higher ratio's  of 3.27   or  std  3.89 if  OD  was fitted

the 3.63 is a  good compromise   you dont want to over  gear it or things like hill starts etc need excessive clutch slip times to get her moving



Pete

[Jonny-Jimbo]

Quoted from Pete Lewis

Rimmers have a data problem or typo.

A more accurate statement would be 'Rimmers have a problem', or even 'Rimmers are a problem'. Overpriced tat, and as said, information is often incorrect.

[Steve AKA vitessesteve]

My Vitesse Mk2 has had a 3.63 diff + overdrive for some time now.  I can remember how loud it was when I first had it with the standard 3.89 and no overdrive. Still not exactly civilised at motorway speeds but much more bearable.

The rev counter is relined at 5500 to 6000.  I would be very surprised if you get anywhere near the limit unless you drive it hard in the lower gears (or go chasing BMWs etc ).  

[RobPearce]

Quoted from Jonny-Jimbo

A more accurate statement would be 'Rimmers have a problem', or even 'Rimmers are a problem'. Overpriced tat, and as said, information is often incorrect.

My local garage tried to get a clutch for my Toledo one time, and their supplier checked with Rimmers for what type to get. Rimmers believed that the Toledo was FWD and couldn't supply one. Once I was called in and explained the situation, the intermediary were able to supply the right bits off the shelf... because they deal with Spitfires frequently.

[Joner]

This problem is now solved.  It was indeed a faulty rev counter.  I used the sites recommended by thebrookster http://www.mintylamb.co.uk/gearspeed/ to calculate speed in mph for each given gear at 5500 revs and comited them to memory.  I downloaded a free gps speedo and checked the calibration of mine which I found to be correct.  I then took the car up to each speed in each gear.

The rev counter immediately went through the red line, out the other side then dropped to the six o'clock position which is where it has stayed (or waggled about there to be precise) ever since .

Many thanks to all involved.  I'm delighted.  This is now an entirely different car to the one I had yesterday.  No more being overtaken by women on the school run in a Fiat Punto while I'm "redlining" it in top gear!  I could easily have spent silly money sorting this out so I'll buy you all a beer unless I never see you or I forget.  Thanks again. Joner

[MDofTW]

Thank you for this thread - it's cheered me up no end. I've not had a speedo for 9 months (don't ask!), but having checked out my revs against that website, I reckon my Mk 2 Vitesse has been scampering along rather better than I thought- unless it's also got Joner's disease! Mind you it was a 'bit of a moment' driving at a mobile speed camera in a 30 the other day - with no- one in front to set the speed of course! Fingers crossed.

[RobPearce]

Hehe! My GT6 went through a couple of long periods without a speedo, due to broken cable and the right-angle drive falling out of the overdrive. I finally fixed it properly when the rev counter cable snapped too... 😉