What speed?

What speed?

Author
Discussion

GBGaffer

Original Poster:

546 posts

277 months

Wednesday 24th April 2002
quotequote all
My speedo has started to exhibit some strange symptoms. When starting from cold, the needle hunts about ~+/- 10mph of the correct speed. After a while it settles down and indicates the correct (I guess) speed. I have also noticed the problem is worse when in fourth gear, and it disappears on the upchange to fifth. Anyone had a similar problem?

Also anyone know the actual speed/rpm relationship in fifth in case the thing finally gives up the ghost.

Thanks in anticipation

Cheers

Graham

HarryW

15,279 posts

276 months

Wednesday 24th April 2002
quotequote all
Graham still trying to get to the bottom of my speedo, works 99% of the time being now sorted as part of the service in May with DB. When it has played up I've used the following:-

2000 rpm in 3rd = 30mph
2000 rpm in 4th = 40mph
2000 rpm in 5th = 50mph
3000 rpm in 5th = 75ish

That should keep you out of trouble, however thats for a V8S! and I'm not sure if the S4 has the same ratio's? anyone else??

Harry

GBGaffer

Original Poster:

546 posts

277 months

Wednesday 24th April 2002
quotequote all
Thanks Harry

Those ratios seem to be about the same as the 'mean' speed so I'll use them as a guideline.

How's the V8 these days? Hope to see you around sometime.

All the best

Graham

HarryW

15,279 posts

276 months

Wednesday 24th April 2002
quotequote all
Graham

Glad to be of service, I may see you if you go to the Dorset meet in May?
The motors running like a dream, touch wood, just a couple of gremlins, don't they all have them? Due service in June but bringing it forward to May to sort out the niggles, speedo, reversing lamp, upper steering UJ, oh yeah tyres are imminent too

Are you still considering a larger lump for the S4?

Harry

GBGaffer

Original Poster:

546 posts

277 months

Thursday 25th April 2002
quotequote all
Hi Harry

Good to hear the S is fine. I've been indulging in a lot of open air S'ing, backwards and forwards to Soton each day, and occasionally feel it would be nice to have some more power. I'm sure the experts will say 'buy a Griff etc.' but I prefer the look of the S, and being a bit stubborn, tend to want to do the opposite to the sensible route.

Richard at Peninsula started me thinking about it, with tales of 'you could probably fit a short block 5.7ltr Chevy', and then I compounded this daydream by stumbling on a web site that offered complete V10 Viper engines! Must get the tape measure out.

But seriously, it isn't going to happen this year, as I'm working flat out on the boat, but hey it doesn't stop me thinking about it Just to cap it all I saw an ad on PH this week offering a complete TVR/Rover 4.0 V8 complete with ECU from a guy doing a 5.0 upgrade, which started the ball rolling again.

I'm sure the practicalities of upgrading the engine, will prove to be offputting, not least of which is the problem of having to retain the Catalytic converters, and the fact that the insurers would probably load the premium more for having a modified S4 than if I were to buy a Griffith/Chimaera.

Oh well, dream on.

Hope to see you in May

Cheers

Graham

GreenV8S

30,486 posts

291 months

Thursday 25th April 2002
quotequote all
quote:


2000 rpm in 3rd = 30mph
2000 rpm in 4th = 40mph
2000 rpm in 5th = 50mph
3000 rpm in 5th = 75ish




The speedo on my V8S shows 7, 11, 17, 21, 27 mph/1000 rpm. It's actually pretty accurate, checked against GPS, but of course I've changed the diff ratio so originally it must have been way out. V6 has a different 'box of course so the ratios won't be identical.

Paul V

4,489 posts

284 months

Thursday 25th April 2002
quotequote all
quote:
My speedo has started to exhibit some strange symptoms. When starting from cold, the needle hunts about ~+/- 10mph of the correct speed. After a while it settles down and indicates the correct (I guess) speed. I have also noticed the problem is worse when in fourth gear, and it disappears on the upchange to fifth. Anyone had a similar problem?

Also anyone know the actual speed/rpm relationship in fifth in case the thing finally gives up the ghost.

Thanks in anticipation

Cheers

Graham


Might be worth checking earth wire on the chassis, its just inside the near side front wheel arch, mine started playing up when the earth was dodgy.

Paceracing

729 posts

273 months

Thursday 25th April 2002
quotequote all
In 4th gear you get a very accurate speed versus rpm.
i.e.
1000 rpm = 20 mph
2000 rpm = 40 mph
3000 rpm = 60 mph
4000 rpm = 80 mph
5000 rpm = 100 mph
6000 rpm = very loud bang from the engine!

Therefore it follows that if in 4th gear if the rev counter says 3500 rpm, you would be doing 70 mph.

Jas.

M@H

11,298 posts

279 months

Thursday 25th April 2002
quotequote all
I think you get 23 mph per 1000 rpm in 5th:
46 mph = 2000rpm
3043rpm = 70mph

Cheers
Matt.

johno

8,520 posts

289 months

Thursday 25th April 2002
quotequote all
Nice one !!

Have just come back from going out to the dentist. I was very very late and have waited for 8 months to get this crown jobby sorted...long story.

Anyway due to my being late I was with roof off and foot flat to the boards.

I had 6000rpm indicated in 5th and was wondering what speed that equated too as the speedo stopped at 120mph.

I don't reckon it was doing much more than that as the calculation equates to 138mph.

Obviously my dentist is in Germany

M@H

11,298 posts

279 months

Thursday 25th April 2002
quotequote all
138... blimey!.. mine gets a bit too jumpy for my liking over about 100, even though I've had the geometry done.. it just seems to bounce about a bit much.. (saying that I only drive it on A & B roads.. its probably much better on the Motorway)

Cheers
Matt.

johno

8,520 posts

289 months

Thursday 25th April 2002
quotequote all
Remeber though that mine is sitting quite low I would guess and very stiff.

I am not saying I was doing that speed but I did put in round a long sweeping *very open and visible* motorway bend today a 110mph and it felt rooted. Excellent stuff !!

Problem is that I'm still not happy with the Gaz damper set up as I feel they are impedeing the ride height I want at the back and whatever I seem to do with the front they are never high enough. To be fair I haven't played at it for a while.

Cheers

Mark

Paceracing

729 posts

273 months

Thursday 25th April 2002
quotequote all
Mark,
Rather sadly I calculated the true speed of the car using RPM, gear ratio, final drive ratio and tyre diameter. (I need to get out more).
My calculations indicated 6000 RPM = 139.384 MPH.
Good work fella!
(P.S. for any doubters, I also have a dentist in Germany and have clocked 6000 RPM in 5th).

Jas.

johno

8,520 posts

289 months

Thursday 25th April 2002
quotequote all
WOW WOW WOW !!!!

Matt,

I've just looked at your profile and your car could be mine !!!!!

Except that I have far more 'white' stone chips in the front. In fact it looks like it has been shotblasted.

Cheers

Mark

johno

8,520 posts

289 months

Thursday 25th April 2002
quotequote all
quote:

Mark,
Rather sadly I calculated the true speed of the car using RPM, gear ratio, final drive ratio and tyre diameter. (I need to get out more).
My calculations indicated 6000 RPM = 139.384 MPH.
Good work fella!
(P.S. for any doubters, I also have a dentist in Germany and have clocked 6000 RPM in 5th).

Jas.




M@H

11,298 posts

279 months

Thursday 25th April 2002
quotequote all
quote:

WOW WOW WOW !!!!

Matt,

I've just looked at your profile and your car could be mine !!!!!

Except that I have far more 'white' stone chips in the front. In fact it looks like it has been shotblasted.

Cheers

Mark




Cool.. nice one.. yeah my fronts still a bit of a virgin on stonechips since a respray a couple of years back. its the BEST colour isnt it

PS ..pleased to hear my 23mph per 1000 worked out right to the techhie amongst us BTW

johno

8,520 posts

289 months

Thursday 25th April 2002
quotequote all
quote:

WOW WOW WOW !!!!

Matt,

I've just looked at your profile and your car could be mine !!!!!

Except that I have far more 'white' stone chips in the front. In fact it looks like it has been shotblasted.

Cheers

Mark




On top of the looks my Reg is F908 PRK.....how spooky is that as yours is F90 PPK ...... not far off eh !!

I have met the guy who F906 PRK, which was on a 350i I think at Mania a couple of years ago.

We must get a photo of the cars together.

Cheers

Mark

M@H

11,298 posts

279 months

Thursday 25th April 2002
quotequote all
JOHNO... I Have disgused my REG... Mine is F904 PRK !!

Holy SHit !!

M@H

11,298 posts

279 months

Thursday 25th April 2002
quotequote all
Yours or mine



Cheers
Matt.

johno

8,520 posts

289 months

Thursday 25th April 2002
quotequote all
quote:

JOHNO... I Have disgused my REG... Mine is F904 PRK !!

Holy SHit !!




Thought you may have done !!!

Supplied by TVR Centre at Barnet. I still have the original plates with the bulldog sticker !!

Holy Shit !! They're almost siblings !!!!

Mines Arabian Blue with a Black Vinyl interior. It now has a blue roof which is how it was originally supplied but later was changed to a black one. Since changed it back.

Stunned, excellent stuff !!!!!

Mark