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Volvo Servo Upgrade


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12 hours ago, Tony M said:

All great information. Thanks again. I have ordered the servo just looking for a supplier for the aluminium. 

These people may be convenient as it’s a post service supply.

 https://www.metals4u.co.uk

H

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I finally got out for a road test today with the new servo and what a transformation. The first time I used the brakes it came as a bit of a shock and I very nearly left a face print of my ugly mug on the windscreen. The brakes now have the power and feel of a modern car and at the top end of that classification too. Without exaggeration I can say they are about as good as anyone will ever need or want for either road or track. Absolutely face distorting with minimal effort! I need to adjust the servo actuator rod a little to remove 1/2" of slack (at the pedal rubber) between first touch and servo engagement to smooth things out a little but quite honestly that is just me being a perfectionist. If anything when combined with the big rear drums and AP 4 pots on the front it's a little over braked but I can live with that in comparison to what it was before.

This simple and fairly pain free mod is definitely on my "recommend" list.

 

 

 

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1 hour ago, Robert Price said:

Audi vacuum assist fitted to the 6 recently purchased, brakes felt really good.

Rob

Audi Brake Booster 1.jpg

Hi Robert. Have you fitted a one way valve between the tee and the manifold?  My setup relies on the pump only (although planning to connect back to the manifold shortly) and without a one-way valve between these two points the pump will be trying to pull a vacuum in the manifold.  Perhaps it's not showing in the photo?

Gavin

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Yes Gavin there is a 1 way valve arrow pointing toward the manifold. I have just removed it all actually, the previous owner fitted it but the unit was mounted on a single rubber anti vibration fitting and when activated the whole unit wobbled violently and I was also not happy about some additional feed wiring added since the photo, fitted apparently due to an occasional failure of the pressure switch to operate. So I will see how the car performs without it and I may put it back to my own satisfaction later.

 

Rob

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9 hours ago, Robert Price said:

Yes Gavin there is a 1 way valve arrow pointing toward the manifold. I have just removed it all actually, the previous owner fitted it but the unit was mounted on a single rubber anti vibration fitting and when activated the whole unit wobbled violently and I was also not happy about some additional feed wiring added since the photo, fitted apparently due to an occasional failure of the pressure switch to operate. So I will see how the car performs without it and I may put it back to my own satisfaction later.

 

Rob

Rob, as a suggestion should you decide to revisit your setup, perhaps consider using an adjustable switch such as the automatic transmission type I've used.  This allows me to adjust the amount of vacuum to the booster - currently running 13".

Gavin

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Gavin

Can you give me the adjustable switch details where you obtained it please? I understand from the previous owner the vacuum was set at -18psi but I am not familier with this type of modification still learning.

Rob

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2 hours ago, Robert Price said:

Gavin

Can you give me the adjustable switch details where you obtained it please? I understand from the previous owner the vacuum was set at -18psi but I am not familier with this type of modification still learning.

Rob

This is it here Rob - plenty on the US eBay site.

Superior K058 Transmission Vacuum Switch Kit TH200-4R TH700-R4 81-90 | eBay

I can't get the link to work so just search eBay for that part.

Gavin

Edited by KiwiTR6
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On 11/1/2021 at 9:27 AM, FatJon said:

A small addendum.

Don't forget to adjust the clearance between the servo actuator rod and the master cylinder piston or you will end up at the roadside with the brakes locked on. A big thanks to the chaps at Racestorations for the rescue!

 

Hi Jon. Yes I was just going to ask that! I have received my servo and offered it up but I did notice that the central pin is proud compared to the original. It does look as though it wont adjust in any more though. Did you adjust it?

 Did you use allen bolts to mount the plate into the bulkhead? Many thanks for you posts.

Having just re read your post: .....

As a little update you don't need to "adjust" the bottom of the inner wing if you use bolts from inside the car to fix it rather than studs from the mounting plate and nuts inside. That occurred to me after I had finished, as the best ideas always do!

I think I will now try and bolt from inside as you suggest. It may be possible to helicoil the original block and mill out the 4 recesses to hold the servo nuts Ill get back about this and post a picture if it works.  :-) 

 

Volvo servo pin.jpg

98C13D27-1D1B-4B3A-A62F-E72736955E14.JPG

Edited by Tony M
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Yes, again with hindsight it may be possible to drill the old block but from memory it's a little thinner. Try it, nothing to lose.

Will come back on the adjustment. The mechanics are doing that as they have the gauge to do it very precisely but what I can tell you is that it really aint too critical. To get me moving after the “problem” we just put in a thick (3mm) spacer between servo and master cylinder and it all worked just fine. The piston surface which the rod touches is slightly recessed in the master so the servo rod should be slightly proud anyway. I think worst case is to take the lock nut off the rod, thin it by a few thou and put it back on to gain a bit of clearance if needed. I will bet it varies a bit from one car to another anyway depending on the master cylinder brand.

 

 

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Collected the now adjusted car today. The required clearance is to have the pintle on the servo 16thou below the servo flange. The locknut was too thick so this was achieved by using a suitably sized washer and tightening the rod with some loctite on the adjustment thread. I suppose the same might be achieved with a thinner locknut but I wasn't there so I can't comment on that. All now working perfectly.

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5 hours ago, FatJon said:

Collected the now adjusted car today. The required clearance is to have the pintle on the servo 16thou below the servo flange. The locknut was too thick so this was achieved by using a suitably sized washer and tightening the rod with some loctite on the adjustment thread. I suppose the same might be achieved with a thinner locknut but I wasn't there so I can't comment on that. All now working perfectly.

Great thanks for the feedback. My original servo has to be just below the front surface, as I did have a problem with the brakes binding after I adjusted it a bit too high, so I will look to repeat this position.

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On 11/5/2021 at 7:14 AM, Andy Moltu said:

Will your vacuum assist be affecting the pressure in the inlet manifold?

If iit drops the pressure in the inlet manifold it may impact on the fuelling of the Lucas PI which uses the vacuum to control the fuelling.

A one-way valve will prevent this from happening plus I doubt the electric pump will be grunty enough to have any influence.

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Having just completed my install I thought I would post the way I had completed the mod. First off the road test has proved what a brilliant upgrade this is. The brakes are now much more powerful. A real modern car touch.

Having looked carefully at the previous installs that used a new block of aluminium I thought that the original spacer would actually work.

I drilled the existing spacer holes out to 10.2mm and tapped to 12mm. I purchased inserts that reduced from 12 to 8mm threads. I wound these in tight with an Allen bolt with a bit of oil on it, so that when reversed it would release from the insert easily. https://www.ebay.co.uk/itm/222455691053?var=522319792217

These fitted flush really nicely. The idea being to use Allen bolts from inside the car to secure the servo instead of fitting studs to the spacer. This made installation easier than the original servo! The spacer had to be marked accurately for the locations of the studs on the new servo. These are clearance holes. The spacer then needs to have recesses cut that would allow the nuts to be tightened by a slim line socket. This was achieved using a miller. It’s the only way to get a flat accurate hole (Many thanks to Neil from our local TR club for his help with this). As has been previously mentioned this spacer for right hand drive cars is made square and not offset. This installation meant that the inner wing did not need to be dented at all! It fits snugly but without any problem. The length of the clevis pin clamp needs to be modified as it will leave the pedal much higher than original. I cut the nut off and filed two edges down on the locknut so it would fit inside the bracket and allow it to be locked up. I had to cut the shaft shorter by half an inch or so. This allows a good range of height adjustment for the pedal. One thing to watch out for is the small doomed head that pushes into the master cylinder. I needed to reduce the length. I managed this by removing the threaded pin and locknut. I filed the locknut to half its thickness. I also had to file the dome down a small amount. This then gave me the original height compared to the original servo. Failure to set this height right will cause the brakes to bind on, so it’s worth spending the time to get it right. A quick tip is to have someone in the car to hold the brake pedal down to push the shaft out. I then wrapped insulation tape around the last inch of the shaft and held it with mole grips so it didn’t rotate when taking the central adjust pin out. The insulation tape reduces any damage and improves the grip. Finally the brake pipes will need to be remade to give a neat appearance. I might be fitting residual pressure valves to hopefully remove that first pedal push that gives longer travel. These are sold by various companies but are available from eBay at a much reduced price. This is the one I bought. https://classic-volvo.com/rem-bekrachtiger-oem-ref-9157699-91576991-volvo-onderdeel-35309772_b.html 120 euros including delivery to UK.

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Edited by Tony M
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On 11/15/2021 at 5:21 PM, Tony M said:

Having just completed my install I thought I would post the way I had completed the mod. First off the road test has proved what a brilliant upgrade this is. The brakes are now much more powerful. A real modern car touch.

Having looked carefully at the previous installs that used a new block of aluminium I thought that the original spacer would actually work.

I drilled the existing spacer holes out to 10.2mm and tapped to 12mm. I purchased inserts that reduced from 12 to 8mm threads. I wound these in tight with an Allen bolt with a bit of oil on it, so that when reversed it would release from the insert easily. https://www.ebay.co.uk/itm/222455691053?var=522319792217

These fitted flush really nicely. The idea being to use Allen bolts from inside the car to secure the servo instead of fitting studs to the spacer. This made installation easier than the original servo! The spacer had to be marked accurately for the locations of the studs on the new servo. These are clearance holes. The spacer then needs to have recesses cut that would allow the nuts to be tightened by a slim line socket. This was achieved using a miller. It’s the only way to get a flat accurate hole (Many thanks to Neil from our local TR club for his help with this). As has been previously mentioned this spacer for right hand drive cars is made square and not offset. This installation meant that the inner wing did not need to be dented at all! It fits snugly but without any problem. The length of the clevis pin clamp needs to be modified as it will leave the pedal much higher than original. I cut the nut off and filed two edges down on the locknut so it would fit inside the bracket and allow it to be locked up. I had to cut the shaft shorter by half an inch or so. This allows a good range of height adjustment for the pedal. One thing to watch out for is the small doomed head that pushes into the master cylinder. I needed to reduce the length. I managed this by removing the threaded pin and locknut. I filed the locknut to half its thickness. I also had to file the dome down a small amount. This then gave me the original height compared to the original servo. Failure to set this height right will cause the brakes to bind on, so it’s worth spending the time to get it right. A quick tip is to have someone in the car to hold the brake pedal down to push the shaft out. I then wrapped insulation tape around the last inch of the shaft and held it with mole grips so it didn’t rotate when taking the central adjust pin out. The insulation tape reduces any damage and improves the grip. Finally the brake pipes will need to be remade to give a neat appearance. I might be fitting residual pressure valves to hopefully remove that first pedal push that gives longer travel. These are sold by various companies but are available from eBay at a much reduced price. This is the one I bought. https://classic-volvo.com/rem-bekrachtiger-oem-ref-9157699-91576991-volvo-onderdeel-35309772_b.html 120 euros including delivery to UK.

IMG_2792.jpg

s-l1600.png

IMG_2791.jpg

A619F8BB-ED6A-44B0-A71C-533554EF587B.JPG

IMG_2794.jpg

IMG_2801.jpg

IMG_2803.jpg

IMG_2804.jpg

IMG_2805.jpg

IMG_2815.jpg

IMG_2814.jpg

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Hi Tony,

On the clevis pin end, I do not see a threaded rod or a nut welded onto the clevis pin bracket (or am I missing something) the link for the servo does not show a threaded end 

clevis pin bracket.

Just love what you have done.

Regards Harry.

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On 9/10/2021 at 2:28 PM, stuart said:

I`m the same, if all the rest of the system is up to snuff then the brakes are very good. I dont even have a servo on my 4a and I can lock up all 4 without too hard a push on the pedal.

Stuart.

Hi all,

also no problem here to lock all 4 brakes on my TR4A without a problem,

not like on a modern car but absolutely OK (I use a 0.625“ master, very pleased with this „booster“)

When I compared the brake pedal mechanism of my 4A and a TR6 I noticed

they had to make the leverage ratio much worse on the 6 to avoid overdoing with the servo.

This is why the TR6 brakes really bad with a not working servo.

This might be very simple knowledge but worth to point out?

Ciao, Marco

Edited by Z320
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13 hours ago, harrytr5 said:

Hi Tony,

On the clevis pin end, I do not see a threaded rod or a nut welded onto the clevis pin bracket (or am I missing something) the link for the servo does not show a threaded end 

clevis pin bracket.

Just love what you have done.

Regards Harry.

Hi Harry. Thanks.  I agree that the picture shown on the advert doesn't show a threaded rod for the clevis pin clamp, but I ordered that and it came with the threaded end. At the point of ordering I didn't really consider that there might be a problem with the length or adjustment. I was looking for the part number 9157699 and took a chance.

 In the pictures I show a closeup of the clevis bracket held in the vice before I used a junior hacksaw to cut along the 2 welds that held the silver nut on. I then adjusted the thinner bronze lock nut by filing 2 edges, so that it would slide inside the bracket and the two nuts could then be set anywhere to alter the length and rotational position of the bracket. I had to shorten the shaft a bit to get the position I needed.

Regards

Tony

IMG_2816.jpg

IMG_2814.jpg

IMG_2815.jpg

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12 hours ago, Z320 said:

Hi all,

also no problem here to lock all 4 brakes on my TR4A without a problem,

not like on a modern car but absolutely OK (I use a 0.625“ master, very pleased with this „booster“)

When I compared the brake pedal mechanism of my 4A and a TR6 I noticed

they had to make the leverage ratio much worse on the 6 to avoid overdoing with the servo.

This is why the TR6 brakes really bad with a not working servo.

This might be very simple knowledge but worth to point out?

Ciao, Marco

Hi Marco. I just wanted more bite without having to stamp on it. I have uprated the calipers on this 5 but it still needed a really heavy stamp. My ankles are not as strong as they once were and this has really made  a reassuring improvement. I may look at lightening the clutch as well now. The remote servo shown previously in this thread is something that I may look into.

Regards

Tony

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Hi Tony,

that's fine, I hope my statement is without any judgement or assessement.

I just wanted to explain the difference TR4 VS TR6. I also made my clutch easy going

(with a hydraulic release untit) for my convenience, I love it.

Ciao, Marco

 

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