Bristol 410 RPM

[livermoreb]

Is there a chart anywhere showing how many RPM the engine should be doing for any given speed? My 1969 410 seems to rev very highly - to get to 70 mph I am pushing the 5000 revs red line,. I am sure this can't be mormal.

[Calibrator]

From recollection 70 mph was at around 3000 rpm. Has this problem arisen recently? Sounds perhaps like the gearbox isn't changing up?

[herrbartlet]

I think you're stuck in 2nd! I've just got mine on the road and at 60mph, it's just ticking over at 2000rpm. Haven't been any faster, yet, but at 70mph I'd expect the revs to be in the 2250 to 2500 range. Hope this helps.

[Sam410]

Check your rev counter. My 410's rev counter over reads by at least 1000rpm, and I've heard of other cars which suffer this. The speedo waves wildly around a roughly correct centre, but the rev counter is smooth, stable, and wrong. To check it, I bought a cheap laser tachometer from ebay that uses a reflector stuck onto the nose of the crankshaft to count revolutions.

[guymd]

I think it should be closer to the low 3,000s. Is it possibly not in the highest gear?

[livermoreb]

I am pretty sure the gearbox is changing up as I tried changing down to 2 and 1 and there was a noticeable difference.

As for the rev counter, I am fairly confident that the revs were too high because the engine cut out when it went over the 5,000 line but started again when I used the starter after I had stopped.

Automatic gearboxes are a bit of a mystery to me but could it be slipping or something? If so are there adjustments that might be made?

[John Simmons]

I don't have a 410 but what you are experiencing is definitely not correct. My 404 runs 63 mph at 3000 rpm. According to this site you should be about 78 mph at 3000 rpm in top gear, and 90 mph at 5000 rpm in 2nd gear.

Specs 1991 BMW 850i automatic

Other posters have already given advice on some possible problems (calibration of tachometer, not shifting into top gear....). Another might be slippage, either in the torque converter or the ring gear brake bands in the gearbox (but I expect that you would be able to smell the overheating).

In any case, I would have this checked right away.

[John Simmons]

Oddly enough, the link does not go to the correct place, even though I copied it from the site I found through google.

[John Simmons]

But to answer your original question, here is copied the speeds in gears section from the website I linked to.

1000rpm speed:

(km/h/mph)

I: 17.2 / 10.7

II: 29.1 / 18.1

III: 42.2 / 26.2

Final drive ratio std: 3.07

Standard tires: 6.70 H 15


The link I posted does take you to the correct site, but then you will have to click on the "browse by make/model/type" tab in the heading and find the Bristol 410. Then the "detailed specifications and technical data" to get to the page where I found the speeds in gears.

[Peter.Kent]

With the 410 I think you'll find a list of gears/ RPM/ and speeds in the contemporary road tests which you'll find in "Bristol Cars - Brooklands portfolio " P

[PEU186F]

I spent many years wondering why my 410 was showing so many rpm for a given mph but I learnt a salutary lesson "use your head and do not necessarily trust the instruments" when the petrol gauge sender failed. The car started running out of petrol while the gauge said full (NB the quick acting moving coil gauges that Bristols used fail to full), my brain trusted the guage and started to create all sorts of reasons for fuel not getting to the right place, but it never dawned on me that the problem was actually the guage. To confound the issue the reserve switch had also decided to give up simultaneously - gremlins work in pairs. I was rescued quite quickly by an amused RAC man who went back to first principles and insisted on adding petrol. Worked like a charm.

Emboldened by this knowledge, i.e. it is at least as likely (or perhaps more likely if Lucas were involved) that the guage is at fault I researched the Rev counter to find that over reading is a common problem. So off it went to be fixed and recalibatred. Yes, it was over reading by a considerable factor and now I drive along happily at 70 mph doing just as few actual rpm as before, but, as the counter isn't raising my blood pressure by lying to me, it is astonishing how much more relaxed the car feels.

My advice is to check the Rev counter first and foremost. I used Home page, my only connection is as a satisfied customer.

By the way checking the number of up shifts from a gentle standing start should be easy? Also I am not aware that the 410 ever had any form of rev limiter. Cutting out at an indicated 5000 rpm sounds like another gremlin trying to distract you

[Nick Challacombe]

My 407 at 5,000 revs would be about 125 mph
At Le Mans I did red line it on the Mulsanne Straight and the 137 recorded seemed about right.
At 5000 revs in 2nd gear, I have not tried it! I suspect would be about 70mph.

Tyres should be 6.00 x 16.
Trans ratios on the 407 Low 8.1, 2nd 4.8, Top 3.31,

According to the Motor Road Test of the 407 they gave a max speed of 129.00 mph.
The recommended engine speed limit of 5,100 revs in top gave 122 mph.
Max speed in 2nd gear 70mph, max speed in 1st gear 36mph.

I strongly suggest that if it is reving at 5,000 revs giving an indicated 70mph that it must be stuck in 2nd gear!

Hope this helps, though I doubt it!!

[Geoff Kingston]

My 411 rev counter over reads because it is the wrong type for the type of electronic ignition system fitted so that could be one possibility.
Two thoughts that would get me looking at the transmission, with the car parked in neutral with the engine running accelerate gently up to 5000 rpm., the accelerator should be near the floor.
If when you are driving at 5000 rpm and the pedal is in the same position I would say it is almost certain to be a gearbox problem, if you are sure it is not stuck in second because you say you can manually change down then it must be slipping, I am surprised it is not hot enough for you to smell if that is the case but if you check the transmission dipstick and the fluid is very dark, has a burnt smell to it and feels a bit gritty then you touch it you almost certainly have a band problem in the transmission.
I am not sure what happens when the torque converter fails as that has never happened to me but we have had a lot of problems recently with an American Ford gearbox which the specialist is now convinced is related to the valve body, it has so far destroyed two sets of top gear clutches and bands. The Chrysler gearbox is much better, more robust and I am told a lot easier to rebuild if it does go wrong.
If it is a gearbox problem I would strongly advise changing the torque converter at the same time and flushing the oil cooler or better still fitting a new independent oil cooler then there is no risk of residues of contaminated fluid causing more problems.

[PEU186F]

One coasts into a lay by (in our case on the A34 with the traffic thundering past), an enormous Italian lorry parks up behind you, the driver gets out on the near side, swings a shower head out of the side, strips off completely and enjoys his shower. My wife was entranced.

One presumes a second shower head on the other side for use on the continent

Now for the technical bit. In our case all that happened was that the front end was just disconnected from the back end, no drama but no drive either. I am told however that there is normally lots of noise but no drive.