v8 auto box-slight clunk on downshift

If this is going from second to first at lights or similar it's perfectly normal. If it's adjusted out to a major degree you lose kickdown.
Thanks
Nick
 
mine seems to have poor kickdown,have to really press pedal hard and .......wait
speedo undereads like a dog too
i have a spare clock set but different tpm on speedo head and a 7000 rpm tacho .mine has only a 6000 rpm

both are v8 clock sets,,well i assume mine in car which underreads is correct...ooer
 
Hello Brook,

I have experienced what you describe before, going from third into second. It seems to be a function of how the transmission builder has set it up, as following a rebuild in 1989 or so, my transmission would really thump in such a situation. Subsequent builds improved the situation reducing the thump with the most recent build in 2009 removing it altogether with no loss to the correct shift points or kickdown.

Ron.
 
Provided there is no impediment to full pedal travel such as too many mats beneath your feet, you can adjust the downshift cable to improve the situation in terms of kickdown. Mark the position of the barrel adjuster, loosen the locknut then wind the barrel out one full turn. Tighten the locknut and road test. Before you do this though, make sure that there is no excessive free play in your accelerator linkage and that the rubber bearings that support the throttle rod are intact.

Ron.
 
wheres barrel adjuster,,any pics??
i apporeciate help as wanna get the old bugger back to full health,,maybe i mite get it to a show!!!!!

:mrgreen:
 
brook shaw wrote,...
wheres barrel adjuster,,any pics??
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It is behind the L/H rocker cover at the rear of the engine. Only adjust the cable once you have ruled out the other possibilities.

Ron.
 
What Ron is describing is the set up of the kickdown cable. You really ought to set up the throttle linkage first, as the kickdown cable is critically dependent on this being set correctly. Plus the throttle linkage has a number of rubber bushes in it which are known to go missing over time, preventing you from acheiving full throttle (and performance!). If you don't get full throttle, then the kickdown cable won't be pulled as hard as it should be, hence reluctance to kick down.

The kickdown cable has other functions in the auto box besides just kickdown. It affects the system pressures within the box in normal running, so with a loose cable everything will be a bit early and mushy on up changes. This might seem like it will make your initially reported problem worse, but there is no point addressing that until the kickdown is set correctly. There are other possible external adjustments, such as the tightness of the bands, that can be done after things are 100% on the cable.

Stina did all this during her engine rebuild, so her thread is worth a read. This is my prescription for sorting out the throttle linkage from her thread:

So lets discover the size of the linkage problem first. Get someone to plant a large hoot (or use a breeze block) so that full throttle is engaged in the drivers seat. Engine off, by the way! Now look first at the drivers side carb and see whether it has reached full throttle, Then the passenger side one. If so the linakge issues are finished. If not......

Slacken off the throttle linkage from the nearside carb so that the throttle pedal is effectively disconnected from the carbs. Then reset the linkages so that when you operate the throttle of the nearside carb to full throttle, the drivers side carb reaches full throttle at the same time. Now reconnect the throttle mechanism from the pedal to the nearside carb and see if you can adjust it so that you can achieve full throttle at full pedal movement. If so we've done a major part of setting the carbs! If not we need to track down the lost motion in the throttle linkage from the pedal and see what we can change to tighten it up. Most likely is a missing or decayed rubber bush at the bulkhead where the longitudinal rod starts on its run to the passenger side carb. Suspect no 2 is the rubber bush where the linhage passes into the the cabin and the pedal. Final suspect is the nylon coupling in the middle of the longitubinal rod we've looked at before. All od these are available from the usual suspects.
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and

I've got the parts manual open in front of me and have just given myself a headache! It appears the throttle linkage arrangement changes quite markedly over the course of production! I'm having trouble dissentangling what yours should have. I really need a picture along the bulkhead...

The relevant page is 13 01. I think you should have a single rod which includes the throttle pedal via all sorts of bizarre twists all the way across the bulkhead from side to side. As I read it there is a bolt on bracket inside the car near the throttle pedal which should have a nylon bering bush in it - 534580 - and a further bracket on the engine side of the bulkhead on the passenger side of the heater box wiyh a further nylon bearing bush - 534581. Between the two the cross shaft passes through the bulkhead from inside the car to the engine bay. Where it does that there should be a large rubber gaiter, a bit like a gear lever gaiter, described as a grommet - 577219. Youll be able to see the cross shaft much better with the heads off - it's quite low down. The end of the acceleerator cross shaft on the passenger side in the engine bay should then have a clamp on actuating arm. This arm is then linked to the longitudinal shaft which runs from the bulkhead to the carburettors by a link with a swivel joint at each end. At the bulkhead end of the longitudianl shaft there should be a bolted on support bracket containing a rubber bush - 553851. Then things get interesting. there seem to be a lot of variations of the longitudinal shaft between the bulkhead and the carbs. I think yours should pass almost immediately into a a flexible coupling to cope with the engine rocking. This a nylon spider - 553857. It then passes into a bracket which hold the kickdown cable, where the will be a further nylon bearing bush - 553851. With a further short length shaft we are safely at the carbs.

I'll post this and then go outside and look at mine and post any revisions I think are necessary!

Chris

Yep, tyhat checks out against my car! If you haven't got the parts catalogue yet you can see the relevant page at http://www.rover-classics.co.uk/images/ ... /index.htm on Ian Wilsons Rover- Classics web site.
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Hope that helps!

Chris
 
all throttle linkages and cars were rebuilt by former keeper wen the engine had a overhaul.so seems ok there

car seems ever so undergeared too-hope it6 has the right diff... :shock:
 
brook shaw wrote,...
car seems ever so undergeared too-hope it6 has the right diff...
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In top gear the tacho and speedo should essentially track together when speed is constant. The diff ratio for the V8 is 3.08 : 1, which is the business when it comes to choosing a ratio.

It certainly isn't undergeared, even by today's standards. Back in the 1970s, the gearing was tall indeed.

It certainly sounds like you are not enjoying your P6 experience, which is a pity as the Rover has so much to offer.

Ron.
 
yer i know
the car is show standard,dare i say it concours ?
the former keeper was fastidius,he deffo had attention to detail

he always said the car had a few faults he couldnt cure
i will not be beaten
if i can get my mk1 minis to not have timing chain rattle,not crunch gears etc,,surely gettin my p6 v8 to run spot on shud be a piece of cake,,lol

speedo undereads by 10 mph
clunk on downshift,issues as we have said here
poor kickdown
rattles from suspension

thats it really
the car really gleams and a specialist who posts on here knows the car and says its a fabulous base unit too
suppose i got really lucky with it--just these dreaded niggles!!!!

wanna get it to some shows!!!
 
brook shaw said:
speedo undereads by 10 mph
Click to expand...

brook shaw said:
wanna get it to some shows!!!
Click to expand...

I suspect all V8 speedos under-read to some degree. I used a Sat Nav in a customer's car a few weeks ago and was surprised to see it was actually doing 75mph when the speedo showed an indicated 68-69.

I recently got pulled over by the Gendarmes at a speed trap and told I was doing 44mph, when I was certainly doing an indicated 38-40mph in my Three Thousand Five as I knew they were there. No worries though - they were more interested in the car than giving me a ticket.

RP6C National Rally at Rudgeley, Staffs., September 11th. Also see my events diary at the link on my auto signature.

:D
 
NickDunning said:
If this is going from second to first at lights or similar it's perfectly normal. If it's adjusted out to a major degree you lose kickdown.
Click to expand...

That makes it sound as though they are all like it, and it just has to be accepted. They aren't, and it doesnt, and if the cable is correctly set the thump will dissappear, but the kickdown won't.
 
harveyp6 said:
NickDunning said:
If this is going from second to first at lights or similar it's perfectly normal. If it's adjusted out to a major degree you lose kickdown.
Click to expand...

That makes it sound as though they are all like it, and it just has to be accepted. They aren't, and it doesnt, and if the cable is correctly set the thump will dissappear, but the kickdown won't.
Click to expand...

I bow to your much greater knowledge Harvey.

My source of info on this was none other than Clive Annable when I quizzed him about it a couple of years ago! :eek:
 
NickDunning wrote,...
I suspect all V8 speedos under-read to some degree
Click to expand...

Hello Nick,

The wrong profile tyres will certainly affect the accuracy of the speedo readings. From my own experience, I know that my speedo reads pretty well spot on from having been past the digital speed boards that we have here, even more so when I am the only car there at the time.

Ron.
 
I have found my car clunks at very low speeds for example if I take my foot off the throttle at less than 25mph it goes into third with a clunk.. Is this avoidable?
 
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